[clang] [OpenMP] [NFC] SemaOpenMP.cpp and StmtOpenMP.cpp spelling fixes (PR #96814)

[Michael Klemm via cfe-commits]

https://github.com/mjklemm approved this pull request.

This looks good to me and should be NFC.

https://github.com/llvm/llvm-project/pull/96814
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[clang] [OpenMP] [NFC] SemaOpenMP.cpp and StmtOpenMP.cpp spelling fixes (PR #96814)

[Michael Klemm via cfe-commits]

https://github.com/mjklemm edited 
https://github.com/llvm/llvm-project/pull/96814
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[clang] [flang] [Flang] Re-enable -print-resource-dir compiler option (PR #96799)

[Michael Klemm via cfe-commits]

https://github.com/mjklemm closed 
https://github.com/llvm/llvm-project/pull/96799
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[clang] [flang] [Flang] Re-enable -print-resource-dir compiler option (PR #96799)

[Michael Klemm via cfe-commits]

https://github.com/mjklemm created 
https://github.com/llvm/llvm-project/pull/96799

This PR re-enables the command line option `-print-resources-dir` after PR 
#96557 has reverted the changes made.

The way this works now, is that it simply prints the current resource dir, 
which points to clang/$version.

>From 4384ec3965433ed4590a9403e71dad44ff7b0337 Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Tue, 25 Jun 2024 09:59:42 +0200
Subject: [PATCH 1/2] Add test for -print-resource-dir

---
 flang/test/Driver/print-resource-dir.F90 | 4 
 1 file changed, 4 insertions(+)
 create mode 100644 flang/test/Driver/print-resource-dir.F90

diff --git a/flang/test/Driver/print-resource-dir.F90 
b/flang/test/Driver/print-resource-dir.F90
new file mode 100644
index 00..8fd35f1800df21
--- /dev/null
+++ b/flang/test/Driver/print-resource-dir.F90
@@ -0,0 +1,4 @@
+! DEFINE: %{resource_dir} = %S/Inputs/resource_dir
+! RUN: %flang -print-resource-dir -resource-dir=%{resource_dir}.. \
+! RUN:  | FileCheck -check-prefix=PRINT-RESOURCE-DIR -DFILE=%{resource_dir} %s
+! PRINT-RESOURCE-DIR: [[FILE]]

>From b4e9c8267072384434f957f5181638482ac7dcfc Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Tue, 25 Jun 2024 10:00:56 +0200
Subject: [PATCH 2/2] Add -print-resource-dir command line option for Flang

---
 clang/include/clang/Driver/Options.td | 5 -
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/clang/include/clang/Driver/Options.td 
b/clang/include/clang/Driver/Options.td
index dd55838dcf384b..4c514197de3ac9 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -5535,7 +5535,10 @@ def print_prog_name_EQ : Joined<["-", "--"], 
"print-prog-name=">,
   Visibility<[ClangOption, CLOption]>;
 def print_resource_dir : Flag<["-", "--"], "print-resource-dir">,
   HelpText<"Print the resource directory pathname">,
-  Visibility<[ClangOption, CLOption]>;
+  HelpTextForVariants<[FlangOption],
+  "Print the resource directory pathname that contains lib 
and "
+  "include directories with the runtime libraries and 
MODULE files.">,
+  Visibility<[ClangOption, CLOption, FlangOption]>;
 def print_search_dirs : Flag<["-", "--"], "print-search-dirs">,
   HelpText<"Print the paths used for finding libraries and programs">,
   Visibility<[ClangOption, CLOption]>;

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[clang] [flang] [Flang][Driver] Add -print-resource-dir command line flag to emit Flang's resource directory (PR #90886)

[Michael Klemm via cfe-commits]

mjklemm wrote:

Yeah, go ahead and revert. I can create a new PR from it just print the 
resource dir. 

https://github.com/llvm/llvm-project/pull/90886
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[clang] [flang] [Flang][Driver] Add -print-resource-dir command line flag to emit Flang's resource directory (PR #90886)

[Michael Klemm via cfe-commits]

mjklemm wrote:

@tblah @banach-space Thanks for the reviews! 

https://github.com/llvm/llvm-project/pull/90886
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[clang] [flang] [Flang][Driver] Add -print-resource-dir command line flag to emit Flang's resource directory (PR #90886)

[Michael Klemm via cfe-commits]

https://github.com/mjklemm closed 
https://github.com/llvm/llvm-project/pull/90886
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[clang] [flang] [Flang][Driver] Add -print-resource-dir command line flag to emit Flang's resource directory (PR #90886)

[Michael Klemm via cfe-commits]

https://github.com/mjklemm updated 
https://github.com/llvm/llvm-project/pull/90886

>From 1a994159025f127f0f7d11da80b74035788d52c9 Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Thu, 2 May 2024 14:50:45 +0200
Subject: [PATCH 1/8] Enable -print-resource-dir also for Flang

---
 clang/include/clang/Driver/Options.td | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/clang/include/clang/Driver/Options.td 
b/clang/include/clang/Driver/Options.td
index 864da4e1157f7..a3b81fa338bdc 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -5474,7 +5474,7 @@ def print_prog_name_EQ : Joined<["-", "--"], 
"print-prog-name=">,
   Visibility<[ClangOption, CLOption]>;
 def print_resource_dir : Flag<["-", "--"], "print-resource-dir">,
   HelpText<"Print the resource directory pathname">,
-  Visibility<[ClangOption, CLOption]>;
+  Visibility<[ClangOption, CLOption, FlangOption]>;
 def print_search_dirs : Flag<["-", "--"], "print-search-dirs">,
   HelpText<"Print the paths used for finding libraries and programs">,
   Visibility<[ClangOption, CLOption]>;

>From beee04f6f2d411694f5ae1ee6130a81a632164df Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Thu, 2 May 2024 16:19:38 +0200
Subject: [PATCH 2/8] Add setResourceDir function to set resource directory for
 Flang

This should be an NFC change for anythign, but Flang.
---
 clang/include/clang/Driver/Driver.h |  3 +++
 clang/lib/Driver/Driver.cpp | 23 ---
 2 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/clang/include/clang/Driver/Driver.h 
b/clang/include/clang/Driver/Driver.h
index 2ffc52bcb7ad3..c36595e62e2da 100644
--- a/clang/include/clang/Driver/Driver.h
+++ b/clang/include/clang/Driver/Driver.h
@@ -752,6 +752,9 @@ class Driver {
   /// option.
   void setDriverMode(StringRef DriverModeValue);
 
+  /// Set the resource directory, depending on which driver is being used.
+  void setResourceDirectory();
+
   /// Parse the \p Args list for LTO options and record the type of LTO
   /// compilation based on which -f(no-)?lto(=.*)? option occurs last.
   void setLTOMode(const llvm::opt::ArgList );
diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
index 114320f5d3146..d75d2e88fc102 100644
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -229,9 +229,6 @@ Driver::Driver(StringRef ClangExecutable, StringRef 
TargetTriple,
 UserConfigDir = static_cast(P);
   }
 #endif
-
-  // Compute the path to the resource directory.
-  ResourceDir = GetResourcesPath(ClangExecutable, CLANG_RESOURCE_DIR);
 }
 
 void Driver::setDriverMode(StringRef Value) {
@@ -250,6 +247,25 @@ void Driver::setDriverMode(StringRef Value) {
 Diag(diag::err_drv_unsupported_option_argument) << OptName << Value;
 }
 
+void Driver::setResourceDirectory() {
+  // Compute the path to the resource directory, depending on the driver mode.
+  switch (Mode) {
+  case GCCMode:
+  case GXXMode:
+  case CPPMode:
+  case CLMode:
+  case DXCMode:
+ResourceDir = GetResourcesPath(ClangExecutable, CLANG_RESOURCE_DIR);
+break;
+  case FlangMode:
+// TODO: Is there a better way to add the "../include/flang/" component?
+SmallString<64> relPath{};
+llvm::sys::path::append(relPath, "..", "include", "flang");
+ResourceDir = GetResourcesPath(ClangExecutable, relPath);
+break;
+  }
+}
+
 InputArgList Driver::ParseArgStrings(ArrayRef ArgStrings,
  bool UseDriverMode, bool ) {
   llvm::PrettyStackTraceString CrashInfo("Command line argument parsing");
@@ -1202,6 +1218,7 @@ Compilation *Driver::BuildCompilation(ArrayRef ArgList) {
   if (!DriverMode.empty())
 setDriverMode(DriverMode);
 
+  setResourceDirectory();
   // FIXME: What are we going to do with -V and -b?
 
   // Arguments specified in command line.

>From 5ca34138043ab621582085e7034349c7e726a970 Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Thu, 2 May 2024 20:31:04 +0200
Subject: [PATCH 3/8] Update/add tests fir -print-resource-dir

---
 flang/test/Driver/driver-help-hidden.f90 | 1 +
 flang/test/Driver/print-resource-dir.F90 | 3 +++
 2 files changed, 4 insertions(+)
 create mode 100644 flang/test/Driver/print-resource-dir.F90

diff --git a/flang/test/Driver/driver-help-hidden.f90 
b/flang/test/Driver/driver-help-hidden.f90
index 706b2cb6c2452..73b34bd321c5f 100644
--- a/flang/test/Driver/driver-help-hidden.f90
+++ b/flang/test/Driver/driver-help-hidden.f90
@@ -143,6 +143,7 @@
 ! CHECK-NEXT: -oWrite output to 
 ! CHECK-NEXT: -pedantic   Warn on language extensions
 ! CHECK-NEXT: -print-effective-triple Print the effective target triple
+! CHECK-NEXT: -print-resource-dir Print the resource directory pathname
 ! CHECK-NEXT: -print-target-triplePrint the normalized target triple
 ! CHECK-NEXT: -pthreadSupport POSIX threads in generated code
 ! CHECK-NEXT: -P  Disable linemarker 

[clang] [flang] [Flang][Driver] Add -print-resource-dir command line flag to emit Flang's resource directory (PR #90886)

[Michael Klemm via cfe-commits]

mjklemm wrote:

@tblah Ping :-)

https://github.com/llvm/llvm-project/pull/90886
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[clang] [flang] [Flang][Driver] Add -print-resource-dir command line flag to emit Flang's resource directory (PR #90886)

[Michael Klemm via cfe-commits]

mjklemm wrote:

> and for addressing my comments

More than happy to!  Still learning how to be a proper Flang developer, so I'm 
thankful for all the comments!

https://github.com/llvm/llvm-project/pull/90886
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[clang] [flang] [Flang][Driver] Add -print-resource-dir command line flag to emit Flang's resource directory (PR #90886)

[Michael Klemm via cfe-commits]

mjklemm wrote:

> Do you know the meaning for Classic Flang?

The way `-print-resource-dir` now works should be consistent with how Classic 
Flang works.  If that's not the right response, I guess I got my wires crossed 
and you need to explain it to me. :-) 

https://github.com/llvm/llvm-project/pull/90886
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[clang] [flang] [Flang][Driver] Add -print-resource-dir command line flag to emit Flang's resource directory (PR #90886)

[Michael Klemm via cfe-commits]

@@ -5474,7 +5474,7 @@ def print_prog_name_EQ : Joined<["-", "--"], 
"print-prog-name=">,
   Visibility<[ClangOption, CLOption]>;
 def print_resource_dir : Flag<["-", "--"], "print-resource-dir">,
   HelpText<"Print the resource directory pathname">,
-  Visibility<[ClangOption, CLOption]>;
+  Visibility<[ClangOption, CLOption, FlangOption]>;

mjklemm wrote:

You're correct that user-friendliness should be preferred.  I have updated the 
text to be more explicit about where the path printed will point to.

https://github.com/llvm/llvm-project/pull/90886
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[clang] [flang] [Flang][Driver] Add -print-resource-dir command line flag to emit Flang's resource directory (PR #90886)

[Michael Klemm via cfe-commits]

https://github.com/mjklemm updated 
https://github.com/llvm/llvm-project/pull/90886

>From 1a994159025f127f0f7d11da80b74035788d52c9 Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Thu, 2 May 2024 14:50:45 +0200
Subject: [PATCH 1/7] Enable -print-resource-dir also for Flang

---
 clang/include/clang/Driver/Options.td | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/clang/include/clang/Driver/Options.td 
b/clang/include/clang/Driver/Options.td
index 864da4e1157f7d..a3b81fa338bdcd 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -5474,7 +5474,7 @@ def print_prog_name_EQ : Joined<["-", "--"], 
"print-prog-name=">,
   Visibility<[ClangOption, CLOption]>;
 def print_resource_dir : Flag<["-", "--"], "print-resource-dir">,
   HelpText<"Print the resource directory pathname">,
-  Visibility<[ClangOption, CLOption]>;
+  Visibility<[ClangOption, CLOption, FlangOption]>;
 def print_search_dirs : Flag<["-", "--"], "print-search-dirs">,
   HelpText<"Print the paths used for finding libraries and programs">,
   Visibility<[ClangOption, CLOption]>;

>From beee04f6f2d411694f5ae1ee6130a81a632164df Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Thu, 2 May 2024 16:19:38 +0200
Subject: [PATCH 2/7] Add setResourceDir function to set resource directory for
 Flang

This should be an NFC change for anythign, but Flang.
---
 clang/include/clang/Driver/Driver.h |  3 +++
 clang/lib/Driver/Driver.cpp | 23 ---
 2 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/clang/include/clang/Driver/Driver.h 
b/clang/include/clang/Driver/Driver.h
index 2ffc52bcb7ad3b..c36595e62e2daf 100644
--- a/clang/include/clang/Driver/Driver.h
+++ b/clang/include/clang/Driver/Driver.h
@@ -752,6 +752,9 @@ class Driver {
   /// option.
   void setDriverMode(StringRef DriverModeValue);
 
+  /// Set the resource directory, depending on which driver is being used.
+  void setResourceDirectory();
+
   /// Parse the \p Args list for LTO options and record the type of LTO
   /// compilation based on which -f(no-)?lto(=.*)? option occurs last.
   void setLTOMode(const llvm::opt::ArgList );
diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
index 114320f5d31468..d75d2e88fc1024 100644
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -229,9 +229,6 @@ Driver::Driver(StringRef ClangExecutable, StringRef 
TargetTriple,
 UserConfigDir = static_cast(P);
   }
 #endif
-
-  // Compute the path to the resource directory.
-  ResourceDir = GetResourcesPath(ClangExecutable, CLANG_RESOURCE_DIR);
 }
 
 void Driver::setDriverMode(StringRef Value) {
@@ -250,6 +247,25 @@ void Driver::setDriverMode(StringRef Value) {
 Diag(diag::err_drv_unsupported_option_argument) << OptName << Value;
 }
 
+void Driver::setResourceDirectory() {
+  // Compute the path to the resource directory, depending on the driver mode.
+  switch (Mode) {
+  case GCCMode:
+  case GXXMode:
+  case CPPMode:
+  case CLMode:
+  case DXCMode:
+ResourceDir = GetResourcesPath(ClangExecutable, CLANG_RESOURCE_DIR);
+break;
+  case FlangMode:
+// TODO: Is there a better way to add the "../include/flang/" component?
+SmallString<64> relPath{};
+llvm::sys::path::append(relPath, "..", "include", "flang");
+ResourceDir = GetResourcesPath(ClangExecutable, relPath);
+break;
+  }
+}
+
 InputArgList Driver::ParseArgStrings(ArrayRef ArgStrings,
  bool UseDriverMode, bool ) {
   llvm::PrettyStackTraceString CrashInfo("Command line argument parsing");
@@ -1202,6 +1218,7 @@ Compilation *Driver::BuildCompilation(ArrayRef ArgList) {
   if (!DriverMode.empty())
 setDriverMode(DriverMode);
 
+  setResourceDirectory();
   // FIXME: What are we going to do with -V and -b?
 
   // Arguments specified in command line.

>From 5ca34138043ab621582085e7034349c7e726a970 Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Thu, 2 May 2024 20:31:04 +0200
Subject: [PATCH 3/7] Update/add tests fir -print-resource-dir

---
 flang/test/Driver/driver-help-hidden.f90 | 1 +
 flang/test/Driver/print-resource-dir.F90 | 3 +++
 2 files changed, 4 insertions(+)
 create mode 100644 flang/test/Driver/print-resource-dir.F90

diff --git a/flang/test/Driver/driver-help-hidden.f90 
b/flang/test/Driver/driver-help-hidden.f90
index 706b2cb6c2452c..73b34bd321c5f6 100644
--- a/flang/test/Driver/driver-help-hidden.f90
+++ b/flang/test/Driver/driver-help-hidden.f90
@@ -143,6 +143,7 @@
 ! CHECK-NEXT: -oWrite output to 
 ! CHECK-NEXT: -pedantic   Warn on language extensions
 ! CHECK-NEXT: -print-effective-triple Print the effective target triple
+! CHECK-NEXT: -print-resource-dir Print the resource directory pathname
 ! CHECK-NEXT: -print-target-triplePrint the normalized target triple
 ! CHECK-NEXT: -pthreadSupport POSIX threads in generated code
 ! CHECK-NEXT: -P  Disable 

[clang] [flang] [Flang][Driver] Add -print-resource-dir command line flag to emit Flang's resource directory (PR #90886)

[Michael Klemm via cfe-commits]

https://github.com/mjklemm updated 
https://github.com/llvm/llvm-project/pull/90886

>From 1a994159025f127f0f7d11da80b74035788d52c9 Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Thu, 2 May 2024 14:50:45 +0200
Subject: [PATCH 1/6] Enable -print-resource-dir also for Flang

---
 clang/include/clang/Driver/Options.td | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/clang/include/clang/Driver/Options.td 
b/clang/include/clang/Driver/Options.td
index 864da4e1157f7d..a3b81fa338bdcd 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -5474,7 +5474,7 @@ def print_prog_name_EQ : Joined<["-", "--"], 
"print-prog-name=">,
   Visibility<[ClangOption, CLOption]>;
 def print_resource_dir : Flag<["-", "--"], "print-resource-dir">,
   HelpText<"Print the resource directory pathname">,
-  Visibility<[ClangOption, CLOption]>;
+  Visibility<[ClangOption, CLOption, FlangOption]>;
 def print_search_dirs : Flag<["-", "--"], "print-search-dirs">,
   HelpText<"Print the paths used for finding libraries and programs">,
   Visibility<[ClangOption, CLOption]>;

>From beee04f6f2d411694f5ae1ee6130a81a632164df Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Thu, 2 May 2024 16:19:38 +0200
Subject: [PATCH 2/6] Add setResourceDir function to set resource directory for
 Flang

This should be an NFC change for anythign, but Flang.
---
 clang/include/clang/Driver/Driver.h |  3 +++
 clang/lib/Driver/Driver.cpp | 23 ---
 2 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/clang/include/clang/Driver/Driver.h 
b/clang/include/clang/Driver/Driver.h
index 2ffc52bcb7ad3b..c36595e62e2daf 100644
--- a/clang/include/clang/Driver/Driver.h
+++ b/clang/include/clang/Driver/Driver.h
@@ -752,6 +752,9 @@ class Driver {
   /// option.
   void setDriverMode(StringRef DriverModeValue);
 
+  /// Set the resource directory, depending on which driver is being used.
+  void setResourceDirectory();
+
   /// Parse the \p Args list for LTO options and record the type of LTO
   /// compilation based on which -f(no-)?lto(=.*)? option occurs last.
   void setLTOMode(const llvm::opt::ArgList );
diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
index 114320f5d31468..d75d2e88fc1024 100644
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -229,9 +229,6 @@ Driver::Driver(StringRef ClangExecutable, StringRef 
TargetTriple,
 UserConfigDir = static_cast(P);
   }
 #endif
-
-  // Compute the path to the resource directory.
-  ResourceDir = GetResourcesPath(ClangExecutable, CLANG_RESOURCE_DIR);
 }
 
 void Driver::setDriverMode(StringRef Value) {
@@ -250,6 +247,25 @@ void Driver::setDriverMode(StringRef Value) {
 Diag(diag::err_drv_unsupported_option_argument) << OptName << Value;
 }
 
+void Driver::setResourceDirectory() {
+  // Compute the path to the resource directory, depending on the driver mode.
+  switch (Mode) {
+  case GCCMode:
+  case GXXMode:
+  case CPPMode:
+  case CLMode:
+  case DXCMode:
+ResourceDir = GetResourcesPath(ClangExecutable, CLANG_RESOURCE_DIR);
+break;
+  case FlangMode:
+// TODO: Is there a better way to add the "../include/flang/" component?
+SmallString<64> relPath{};
+llvm::sys::path::append(relPath, "..", "include", "flang");
+ResourceDir = GetResourcesPath(ClangExecutable, relPath);
+break;
+  }
+}
+
 InputArgList Driver::ParseArgStrings(ArrayRef ArgStrings,
  bool UseDriverMode, bool ) {
   llvm::PrettyStackTraceString CrashInfo("Command line argument parsing");
@@ -1202,6 +1218,7 @@ Compilation *Driver::BuildCompilation(ArrayRef ArgList) {
   if (!DriverMode.empty())
 setDriverMode(DriverMode);
 
+  setResourceDirectory();
   // FIXME: What are we going to do with -V and -b?
 
   // Arguments specified in command line.

>From 5ca34138043ab621582085e7034349c7e726a970 Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Thu, 2 May 2024 20:31:04 +0200
Subject: [PATCH 3/6] Update/add tests fir -print-resource-dir

---
 flang/test/Driver/driver-help-hidden.f90 | 1 +
 flang/test/Driver/print-resource-dir.F90 | 3 +++
 2 files changed, 4 insertions(+)
 create mode 100644 flang/test/Driver/print-resource-dir.F90

diff --git a/flang/test/Driver/driver-help-hidden.f90 
b/flang/test/Driver/driver-help-hidden.f90
index 706b2cb6c2452c..73b34bd321c5f6 100644
--- a/flang/test/Driver/driver-help-hidden.f90
+++ b/flang/test/Driver/driver-help-hidden.f90
@@ -143,6 +143,7 @@
 ! CHECK-NEXT: -oWrite output to 
 ! CHECK-NEXT: -pedantic   Warn on language extensions
 ! CHECK-NEXT: -print-effective-triple Print the effective target triple
+! CHECK-NEXT: -print-resource-dir Print the resource directory pathname
 ! CHECK-NEXT: -print-target-triplePrint the normalized target triple
 ! CHECK-NEXT: -pthreadSupport POSIX threads in generated code
 ! CHECK-NEXT: -P  Disable 

[clang] [flang] [Flang][Driver] Add -print-resource-dir command line flag to emit Flang's resource directory (PR #90886)

[Michael Klemm via cfe-commits]

@@ -5474,7 +5474,7 @@ def print_prog_name_EQ : Joined<["-", "--"], 
"print-prog-name=">,
   Visibility<[ClangOption, CLOption]>;
 def print_resource_dir : Flag<["-", "--"], "print-resource-dir">,
   HelpText<"Print the resource directory pathname">,
-  Visibility<[ClangOption, CLOption]>;
+  Visibility<[ClangOption, CLOption, FlangOption]>;

mjklemm wrote:

Do you suggest that the help message needs to be more verbose for Flang?  Clang 
and Classic Flang use the same message.  If it should be more verbose, how 
about this:

*Print the resource directory pathname where Flang stores the 'lib' and 
'include' folder*

https://github.com/llvm/llvm-project/pull/90886
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[clang] [flang] [Flang][Driver] Add -print-resource-dir command line flag to emit Flang's resource directory (PR #90886)

[Michael Klemm via cfe-commits]

https://github.com/mjklemm updated 
https://github.com/llvm/llvm-project/pull/90886

>From 1a994159025f127f0f7d11da80b74035788d52c9 Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Thu, 2 May 2024 14:50:45 +0200
Subject: [PATCH 1/5] Enable -print-resource-dir also for Flang

---
 clang/include/clang/Driver/Options.td | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/clang/include/clang/Driver/Options.td 
b/clang/include/clang/Driver/Options.td
index 864da4e1157f7d..a3b81fa338bdcd 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -5474,7 +5474,7 @@ def print_prog_name_EQ : Joined<["-", "--"], 
"print-prog-name=">,
   Visibility<[ClangOption, CLOption]>;
 def print_resource_dir : Flag<["-", "--"], "print-resource-dir">,
   HelpText<"Print the resource directory pathname">,
-  Visibility<[ClangOption, CLOption]>;
+  Visibility<[ClangOption, CLOption, FlangOption]>;
 def print_search_dirs : Flag<["-", "--"], "print-search-dirs">,
   HelpText<"Print the paths used for finding libraries and programs">,
   Visibility<[ClangOption, CLOption]>;

>From beee04f6f2d411694f5ae1ee6130a81a632164df Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Thu, 2 May 2024 16:19:38 +0200
Subject: [PATCH 2/5] Add setResourceDir function to set resource directory for
 Flang

This should be an NFC change for anythign, but Flang.
---
 clang/include/clang/Driver/Driver.h |  3 +++
 clang/lib/Driver/Driver.cpp | 23 ---
 2 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/clang/include/clang/Driver/Driver.h 
b/clang/include/clang/Driver/Driver.h
index 2ffc52bcb7ad3b..c36595e62e2daf 100644
--- a/clang/include/clang/Driver/Driver.h
+++ b/clang/include/clang/Driver/Driver.h
@@ -752,6 +752,9 @@ class Driver {
   /// option.
   void setDriverMode(StringRef DriverModeValue);
 
+  /// Set the resource directory, depending on which driver is being used.
+  void setResourceDirectory();
+
   /// Parse the \p Args list for LTO options and record the type of LTO
   /// compilation based on which -f(no-)?lto(=.*)? option occurs last.
   void setLTOMode(const llvm::opt::ArgList );
diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
index 114320f5d31468..d75d2e88fc1024 100644
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -229,9 +229,6 @@ Driver::Driver(StringRef ClangExecutable, StringRef 
TargetTriple,
 UserConfigDir = static_cast(P);
   }
 #endif
-
-  // Compute the path to the resource directory.
-  ResourceDir = GetResourcesPath(ClangExecutable, CLANG_RESOURCE_DIR);
 }
 
 void Driver::setDriverMode(StringRef Value) {
@@ -250,6 +247,25 @@ void Driver::setDriverMode(StringRef Value) {
 Diag(diag::err_drv_unsupported_option_argument) << OptName << Value;
 }
 
+void Driver::setResourceDirectory() {
+  // Compute the path to the resource directory, depending on the driver mode.
+  switch (Mode) {
+  case GCCMode:
+  case GXXMode:
+  case CPPMode:
+  case CLMode:
+  case DXCMode:
+ResourceDir = GetResourcesPath(ClangExecutable, CLANG_RESOURCE_DIR);
+break;
+  case FlangMode:
+// TODO: Is there a better way to add the "../include/flang/" component?
+SmallString<64> relPath{};
+llvm::sys::path::append(relPath, "..", "include", "flang");
+ResourceDir = GetResourcesPath(ClangExecutable, relPath);
+break;
+  }
+}
+
 InputArgList Driver::ParseArgStrings(ArrayRef ArgStrings,
  bool UseDriverMode, bool ) {
   llvm::PrettyStackTraceString CrashInfo("Command line argument parsing");
@@ -1202,6 +1218,7 @@ Compilation *Driver::BuildCompilation(ArrayRef ArgList) {
   if (!DriverMode.empty())
 setDriverMode(DriverMode);
 
+  setResourceDirectory();
   // FIXME: What are we going to do with -V and -b?
 
   // Arguments specified in command line.

>From 5ca34138043ab621582085e7034349c7e726a970 Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Thu, 2 May 2024 20:31:04 +0200
Subject: [PATCH 3/5] Update/add tests fir -print-resource-dir

---
 flang/test/Driver/driver-help-hidden.f90 | 1 +
 flang/test/Driver/print-resource-dir.F90 | 3 +++
 2 files changed, 4 insertions(+)
 create mode 100644 flang/test/Driver/print-resource-dir.F90

diff --git a/flang/test/Driver/driver-help-hidden.f90 
b/flang/test/Driver/driver-help-hidden.f90
index 706b2cb6c2452c..73b34bd321c5f6 100644
--- a/flang/test/Driver/driver-help-hidden.f90
+++ b/flang/test/Driver/driver-help-hidden.f90
@@ -143,6 +143,7 @@
 ! CHECK-NEXT: -oWrite output to 
 ! CHECK-NEXT: -pedantic   Warn on language extensions
 ! CHECK-NEXT: -print-effective-triple Print the effective target triple
+! CHECK-NEXT: -print-resource-dir Print the resource directory pathname
 ! CHECK-NEXT: -print-target-triplePrint the normalized target triple
 ! CHECK-NEXT: -pthreadSupport POSIX threads in generated code
 ! CHECK-NEXT: -P  Disable 

[clang] [flang] [Flang][Driver] Add -print-resource-dir command line flag to emit Flang's resource directory (PR #90886)

[Michael Klemm via cfe-commits]

@@ -0,0 +1,3 @@
+! RUN: %flang -print-resource-dir -resource-dir=%S/Inputs/resource_dir \
+! RUN:  | FileCheck -check-prefix=PRINT-RESOURCE-DIR 
-DFILE=%S/Inputs/resource_dir %s

mjklemm wrote:

I'll make the variable a bit clearer in the next update.  That's a good 
suggestion, thanks!

As for `ClangExecutable`, I haven't looked at where this is being defined.  
It's indeed the driver name and not the name of the Clang driver.  So, for 
Flang is actually contains the full path to `flang-new`.

I'm not opposed to renaming it as part of this PR, but it may widen the scope 
and make approval a bit more complex.  So, my feeling is that this refactoring 
should take place in a different PR.  But I can be convinced otherwise.

https://github.com/llvm/llvm-project/pull/90886
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[clang] [flang] [Flang][Driver] Add -print-resource-dir command line flag to emit Flang's resource directory (PR #90886)

[Michael Klemm via cfe-commits]

@@ -0,0 +1,3 @@
+! RUN: %flang -print-resource-dir -resource-dir=%S/Inputs/resource_dir \
+! RUN:  | FileCheck -check-prefix=PRINT-RESOURCE-DIR 
-DFILE=%S/Inputs/resource_dir %s
+! PRINT-RESOURCE-DIR: [[FILE]]

mjklemm wrote:

It does not.  The `/Inputs/resource_dir` part has no relevance and I have 
copied that verbatim from what Clang does for its driver test.  I will change 
this to use DEFINE to simplify it.

https://github.com/llvm/llvm-project/pull/90886
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[clang] [flang] [Flang][Driver] Add -print-resource-dir command line flag to emit Flang's resource directory (PR #90886)

[Michael Klemm via cfe-commits]

mjklemm wrote:

> How does this compare to GFortran and Classic Flang? Anything resembling this 
> flag?

GFortran does not have it, but Classic Flang does.  So, it's closing a gap to 
Classic Flang here as well.

https://github.com/llvm/llvm-project/pull/90886
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[clang] [flang] [Flang][Driver] Add -print-resource-dir command line flag to emit Flang's resource directory (PR #90886)

[Michael Klemm via cfe-commits]

mjklemm wrote:

> What's the definition of "resource dir" for Fortran?

I'd like to at least have it point to where the MODULE files live.

When I look at what clang emits, then Flang's resource directory should rather 
point to the place, where Flang has its `lib` and `include` directories.  So, 
one level above of what I have done in this PR right now.

For reference, Clang outputs this:

```
$ which clang
clang is /usr/bin/clang
$ clang -print-resource-dir
/usr/lib/llvm-14/lib/clang/14.0.0
$ ls /usr/lib/llvm-14/lib/clang/14.0.0
total 36
24 include/   4 lib/   4 share/   4 README.txt
```

At some point, I guess Flang might also have to switch to a scheme that 
includes version numbers to differentiate different resource directories, so 
that multiple different versions of Flang can coexist.  But that's for a later 
PR.

https://github.com/llvm/llvm-project/pull/90886
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[clang] [flang] [Flang][Driver] Add -print-resource-dir command line flag to emit Flang's resource directory (PR #90886)

[Michael Klemm via cfe-commits]

@@ -250,6 +247,25 @@ void Driver::setDriverMode(StringRef Value) {
 Diag(diag::err_drv_unsupported_option_argument) << OptName << Value;
 }
 
+void Driver::setResourceDirectory() {
+  // Compute the path to the resource directory, depending on the driver mode.
+  switch (Mode) {
+  case GCCMode:
+  case GXXMode:
+  case CPPMode:
+  case CLMode:
+  case DXCMode:
+ResourceDir = GetResourcesPath(ClangExecutable, CLANG_RESOURCE_DIR);
+break;
+  case FlangMode:
+// TODO: Is there a better way to add the "../include/flang/" component?
+SmallString<64> relPath{};
+llvm::sys::path::append(relPath, "..", "include", "flang");
+ResourceDir = GetResourcesPath(ClangExecutable, relPath);
+break;

mjklemm wrote:

Reviewers, please let me know if that approach is too simplistic.  I would also 
like to get your feedback on whether this should be pointing to 
`$FLANG_BIN/../include` instead.  Please suggest.

https://github.com/llvm/llvm-project/pull/90886
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[clang] [flang] [Flang][Driver] Add -print-resource-dir command line flag to emit Flang's resource directory (PR #90886)

[Michael Klemm via cfe-commits]

https://github.com/mjklemm created 
https://github.com/llvm/llvm-project/pull/90886

This should be a NFC change for all drivers, but Flang.

>From 1a994159025f127f0f7d11da80b74035788d52c9 Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Thu, 2 May 2024 14:50:45 +0200
Subject: [PATCH 1/3] Enable -print-resource-dir also for Flang

---
 clang/include/clang/Driver/Options.td | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/clang/include/clang/Driver/Options.td 
b/clang/include/clang/Driver/Options.td
index 864da4e1157f7d..a3b81fa338bdcd 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -5474,7 +5474,7 @@ def print_prog_name_EQ : Joined<["-", "--"], 
"print-prog-name=">,
   Visibility<[ClangOption, CLOption]>;
 def print_resource_dir : Flag<["-", "--"], "print-resource-dir">,
   HelpText<"Print the resource directory pathname">,
-  Visibility<[ClangOption, CLOption]>;
+  Visibility<[ClangOption, CLOption, FlangOption]>;
 def print_search_dirs : Flag<["-", "--"], "print-search-dirs">,
   HelpText<"Print the paths used for finding libraries and programs">,
   Visibility<[ClangOption, CLOption]>;

>From beee04f6f2d411694f5ae1ee6130a81a632164df Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Thu, 2 May 2024 16:19:38 +0200
Subject: [PATCH 2/3] Add setResourceDir function to set resource directory for
 Flang

This should be an NFC change for anythign, but Flang.
---
 clang/include/clang/Driver/Driver.h |  3 +++
 clang/lib/Driver/Driver.cpp | 23 ---
 2 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/clang/include/clang/Driver/Driver.h 
b/clang/include/clang/Driver/Driver.h
index 2ffc52bcb7ad3b..c36595e62e2daf 100644
--- a/clang/include/clang/Driver/Driver.h
+++ b/clang/include/clang/Driver/Driver.h
@@ -752,6 +752,9 @@ class Driver {
   /// option.
   void setDriverMode(StringRef DriverModeValue);
 
+  /// Set the resource directory, depending on which driver is being used.
+  void setResourceDirectory();
+
   /// Parse the \p Args list for LTO options and record the type of LTO
   /// compilation based on which -f(no-)?lto(=.*)? option occurs last.
   void setLTOMode(const llvm::opt::ArgList );
diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
index 114320f5d31468..d75d2e88fc1024 100644
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -229,9 +229,6 @@ Driver::Driver(StringRef ClangExecutable, StringRef 
TargetTriple,
 UserConfigDir = static_cast(P);
   }
 #endif
-
-  // Compute the path to the resource directory.
-  ResourceDir = GetResourcesPath(ClangExecutable, CLANG_RESOURCE_DIR);
 }
 
 void Driver::setDriverMode(StringRef Value) {
@@ -250,6 +247,25 @@ void Driver::setDriverMode(StringRef Value) {
 Diag(diag::err_drv_unsupported_option_argument) << OptName << Value;
 }
 
+void Driver::setResourceDirectory() {
+  // Compute the path to the resource directory, depending on the driver mode.
+  switch (Mode) {
+  case GCCMode:
+  case GXXMode:
+  case CPPMode:
+  case CLMode:
+  case DXCMode:
+ResourceDir = GetResourcesPath(ClangExecutable, CLANG_RESOURCE_DIR);
+break;
+  case FlangMode:
+// TODO: Is there a better way to add the "../include/flang/" component?
+SmallString<64> relPath{};
+llvm::sys::path::append(relPath, "..", "include", "flang");
+ResourceDir = GetResourcesPath(ClangExecutable, relPath);
+break;
+  }
+}
+
 InputArgList Driver::ParseArgStrings(ArrayRef ArgStrings,
  bool UseDriverMode, bool ) {
   llvm::PrettyStackTraceString CrashInfo("Command line argument parsing");
@@ -1202,6 +1218,7 @@ Compilation *Driver::BuildCompilation(ArrayRef ArgList) {
   if (!DriverMode.empty())
 setDriverMode(DriverMode);
 
+  setResourceDirectory();
   // FIXME: What are we going to do with -V and -b?
 
   // Arguments specified in command line.

>From 5ca34138043ab621582085e7034349c7e726a970 Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Thu, 2 May 2024 20:31:04 +0200
Subject: [PATCH 3/3] Update/add tests fir -print-resource-dir

---
 flang/test/Driver/driver-help-hidden.f90 | 1 +
 flang/test/Driver/print-resource-dir.F90 | 3 +++
 2 files changed, 4 insertions(+)
 create mode 100644 flang/test/Driver/print-resource-dir.F90

diff --git a/flang/test/Driver/driver-help-hidden.f90 
b/flang/test/Driver/driver-help-hidden.f90
index 706b2cb6c2452c..73b34bd321c5f6 100644
--- a/flang/test/Driver/driver-help-hidden.f90
+++ b/flang/test/Driver/driver-help-hidden.f90
@@ -143,6 +143,7 @@
 ! CHECK-NEXT: -oWrite output to 
 ! CHECK-NEXT: -pedantic   Warn on language extensions
 ! CHECK-NEXT: -print-effective-triple Print the effective target triple
+! CHECK-NEXT: -print-resource-dir Print the resource directory pathname
 ! CHECK-NEXT: -print-target-triplePrint the normalized target triple
 ! CHECK-NEXT: -pthreadSupport POSIX threads in 

[clang] [flang] [flang][driver] Allow explicit specification of -lFortran_main (PR #78152)

[Michael Klemm via cfe-commits]

mjklemm wrote:

Should this PR be closed at some point?  It seems to be obsolete with the work 
that has been done in the recent past to improve the situation.

https://github.com/llvm/llvm-project/pull/78152
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[clang] [flang] [flang][driver] deprecate manual usage of -lFortran_main (PR #79016)

[Michael Klemm via cfe-commits]

https://github.com/mjklemm approved this pull request.

LGTM

https://github.com/llvm/llvm-project/pull/79016
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[clang] [flang] [flang][driver] deprecate manual usage of -lFortran_main (PR #79016)

[Michael Klemm via cfe-commits]

mjklemm wrote:

I'm OK with landing this for Linux only at this point.

https://github.com/llvm/llvm-project/pull/79016
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[flang] [clang] [flang][driver] Allow explicit specification of -lFortran_main (PR #78152)

[Michael Klemm via cfe-commits]

mjklemm wrote:

> Maybe we should merge a deprecation warning on -lFortran_main before the LLVM 
> release, then make these changes only after the release has branched?

That sounds like a good idea for now.  Then, we can buy a bit of time for the 
RFC and to make decision how we want to deal with the `main` problem (pun 
intended :-)).

https://github.com/llvm/llvm-project/pull/78152
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[flang] [clang] [flang][driver] Allow explicit specification of -lFortran_main (PR #78152)

[Michael Klemm via cfe-commits]

mjklemm wrote:

> In a long run, I still think that we need to get rid of `Fortran_main`. 
> Perhaps, for the minimal, we can rename it to remove `Fortran` in the name to 
> make people think that it is not required (by the users) to do any linking 
> for Fortran code.

I'd agree to that!  The way gfortran does it, seems the best approach.  When 
there's a program unit in the code, gfortran also add a `main` definition to 
that translation unit.  Unfortunately, my knowledge about flang internals is 
not yet there, so I have no clue how to get it to emit the equivalent of the 
`main` in libFortran_main.  I could get away with having it in .ll file or 
something and pull it in from disk, but even that seems to exceed my current 
capabilities. :-)

I could opt-in to make this a learning project for me, but I'd need some hand 
holding to get it done. Volunteers? :-) 

https://github.com/llvm/llvm-project/pull/78152
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[flang] [clang] [flang][driver] Allow explicit specification of -lFortran_main (PR #78152)

[Michael Klemm via cfe-commits]

mjklemm wrote:

I'm kind of split brain on this.  While I do see the issue, I'm not sure if 
this should be considered a bug or a user error.

One thing that come to my mind though is (remotely related to this) to have a 
command line flag that reports the proper libraries needed to successfully link 
a Fortran program using a different linker driver (e.g., clang).  Similar to 
what `mpif90 -showme:link` does for Open MPI:

```
$ mpif90 --showme:link
-I/net/software/x86_64/openmpi/5.0.x/aomp/include 
-I/net/software/x86_64/openmpi/5.0.x/aomp/lib 
-L/net/software/x86_64/openmpi/5.0.x/aomp/lib -Wl,-rpath 
-Wl,/net/software/x86_64/openmpi/5.0.x/aomp/lib -Wl,--enable-new-dtags 
-lmpi_usempif08 -lmpi_usempi_ignore_tkr -lmpi_mpifh -lmpi
```

So, this would look like this at the moment:

```
$ flang -fshow-me-link-line
 "-L/net/software/x86_64/llvm-ml/20231225/lib" "--whole-archive" 
"-lFortran_main" "--no-whole-archive" "-lFortranRuntime" "-lFortranDecimal" 
"-lm"
```


https://github.com/llvm/llvm-project/pull/78152
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[clang] [flang] [flang][driver] Remove Fortain_main static library from linking stages (PR #75816)

[Michael Klemm via cfe-commits]

mjklemm wrote:

Thanks for all the good suggestions! 

https://github.com/llvm/llvm-project/pull/75816
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[flang] [clang] [flang][driver] Remove Fortain_main static library from linking stages (PR #75816)

[Michael Klemm via cfe-commits]

https://github.com/mjklemm closed 
https://github.com/llvm/llvm-project/pull/75816
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[flang] [clang] [flang][driver] Remove Fortain_main static library from linking stages (PR #75816)

[Michael Klemm via cfe-commits]

https://github.com/mjklemm updated 
https://github.com/llvm/llvm-project/pull/75816

>From b3fa63a02f63e6fe0dacc25d584eba2012a5a8c5 Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Sat, 16 Dec 2023 20:15:17 +0100
Subject: [PATCH 1/8] Remove -lFortran_main from the link line when -shared is
 present

---
 clang/lib/Driver/ToolChains/CommonArgs.cpp | 22 ++
 1 file changed, 22 insertions(+)

diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp 
b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 6eb0ed8f3fed9a..939a719c7c7e29 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -1133,6 +1133,17 @@ static bool isWholeArchivePresent(const ArgList ) {
   return WholeArchiveActive;
 }
 
+static bool isSharedLinkage(const ArgList ) {
+  bool FoundSharedFlag = false;
+  for (auto *Arg : Args.filtered(options::OPT_shared)) {
+if (Arg) {
+  FoundSharedFlag = true;
+}
+  }
+
+  return FoundSharedFlag;
+}
+
 /// Add Fortran runtime libs for MSVC
 static void addFortranRuntimeLibsMSVC(const ArgList ,
   llvm::opt::ArgStringList ) {
@@ -1164,6 +1175,17 @@ static void addFortranRuntimeLibsMSVC(const ArgList 
,
 // Add FortranMain runtime lib
 static void addFortranMain(const ToolChain , const ArgList ,
llvm::opt::ArgStringList ) {
+  // 0. Shared-library linkage
+  // If we are attempting to link a shared library, we should not add
+  // -lFortran_main.a to the link line, as the `main` symbol is not
+  // required for a shared library and should also be provided by one
+  // of the translation units of the code that this shared library
+  // will be linked against eventually.
+  if (isSharedLinkage(Args)) {
+printf("MK: --> shared linkage, do not add -lFortranMain\n");
+return;
+  }
+
   // 1. MSVC
   if (TC.getTriple().isKnownWindowsMSVCEnvironment()) {
 addFortranRuntimeLibsMSVC(Args, CmdArgs);

>From a480e16ac94451c635fc6d47df727c47ff3f1b21 Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Mon, 18 Dec 2023 11:27:59 +0100
Subject: [PATCH 2/8] Update dynamic_linker.f90 test and clean up a bit

---
 clang/lib/Driver/ToolChains/CommonArgs.cpp | 22 ++
 flang/test/Driver/dynamic-linker.f90   |  6 +-
 2 files changed, 15 insertions(+), 13 deletions(-)

diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp 
b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 939a719c7c7e29..3b29e1bc75850f 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -1133,15 +1133,14 @@ static bool isWholeArchivePresent(const ArgList ) {
   return WholeArchiveActive;
 }
 
+/// Determine if driver is invoked to create a shared object library (-static)
 static bool isSharedLinkage(const ArgList ) {
-  bool FoundSharedFlag = false;
-  for (auto *Arg : Args.filtered(options::OPT_shared)) {
-if (Arg) {
-  FoundSharedFlag = true;
-}
-  }
+  return Args.hasArg(options::OPT_shared);
+}
 
-  return FoundSharedFlag;
+/// Determine if driver is invoked to create a static object library (-shared)
+static bool isStaticLinkage(const ArgList ) {
+  return Args.hasArg(options::OPT_static);
 }
 
 /// Add Fortran runtime libs for MSVC
@@ -1176,13 +1175,12 @@ static void addFortranRuntimeLibsMSVC(const ArgList 
,
 static void addFortranMain(const ToolChain , const ArgList ,
llvm::opt::ArgStringList ) {
   // 0. Shared-library linkage
-  // If we are attempting to link a shared library, we should not add
+  // If we are attempting to link a library, we should not add
   // -lFortran_main.a to the link line, as the `main` symbol is not
-  // required for a shared library and should also be provided by one
-  // of the translation units of the code that this shared library
+  // required for a library and should also be provided by one of
+  // the translation units of the code that this shared library
   // will be linked against eventually.
-  if (isSharedLinkage(Args)) {
-printf("MK: --> shared linkage, do not add -lFortranMain\n");
+  if (isSharedLinkage(Args) || isStaticLinkage(Args)) {
 return;
   }
 
diff --git a/flang/test/Driver/dynamic-linker.f90 
b/flang/test/Driver/dynamic-linker.f90
index 1cbd407d21ce09..069b51870c91ff 100644
--- a/flang/test/Driver/dynamic-linker.f90
+++ b/flang/test/Driver/dynamic-linker.f90
@@ -3,10 +3,12 @@
 
 ! RUN: %flang -### --target=x86_64-linux-gnu -rpath /path/to/dir -shared \
 ! RUN: -static %s 2>&1 | FileCheck \
-! RUN: --check-prefixes=GNU-LINKER-OPTIONS %s
+! RUN: --check-prefixes=GNU-LINKER-OPTIONS \
+! RUN: --implicit-check-not=GNU-LINKER-OPTIONS-NOT %s
 ! RUN: %flang -### --target=x86_64-windows-msvc -rpath /path/to/dir -shared \
 ! RUN: -static %s 2>&1 | FileCheck \
 ! RUN: --check-prefixes=MSVC-LINKER-OPTIONS %s
+! RUN: --implicit-check-not=MSVC-LINKER-OPTIONS-NOT %s
 ! RUN: %flang -### 

[flang] [clang] [flang][driver] Remove Fortain_main static library from linking stages (PR #75816)

[Michael Klemm via cfe-commits]

https://github.com/mjklemm updated 
https://github.com/llvm/llvm-project/pull/75816

>From b3fa63a02f63e6fe0dacc25d584eba2012a5a8c5 Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Sat, 16 Dec 2023 20:15:17 +0100
Subject: [PATCH 1/7] Remove -lFortran_main from the link line when -shared is
 present

---
 clang/lib/Driver/ToolChains/CommonArgs.cpp | 22 ++
 1 file changed, 22 insertions(+)

diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp 
b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 6eb0ed8f3fed9a..939a719c7c7e29 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -1133,6 +1133,17 @@ static bool isWholeArchivePresent(const ArgList ) {
   return WholeArchiveActive;
 }
 
+static bool isSharedLinkage(const ArgList ) {
+  bool FoundSharedFlag = false;
+  for (auto *Arg : Args.filtered(options::OPT_shared)) {
+if (Arg) {
+  FoundSharedFlag = true;
+}
+  }
+
+  return FoundSharedFlag;
+}
+
 /// Add Fortran runtime libs for MSVC
 static void addFortranRuntimeLibsMSVC(const ArgList ,
   llvm::opt::ArgStringList ) {
@@ -1164,6 +1175,17 @@ static void addFortranRuntimeLibsMSVC(const ArgList 
,
 // Add FortranMain runtime lib
 static void addFortranMain(const ToolChain , const ArgList ,
llvm::opt::ArgStringList ) {
+  // 0. Shared-library linkage
+  // If we are attempting to link a shared library, we should not add
+  // -lFortran_main.a to the link line, as the `main` symbol is not
+  // required for a shared library and should also be provided by one
+  // of the translation units of the code that this shared library
+  // will be linked against eventually.
+  if (isSharedLinkage(Args)) {
+printf("MK: --> shared linkage, do not add -lFortranMain\n");
+return;
+  }
+
   // 1. MSVC
   if (TC.getTriple().isKnownWindowsMSVCEnvironment()) {
 addFortranRuntimeLibsMSVC(Args, CmdArgs);

>From a480e16ac94451c635fc6d47df727c47ff3f1b21 Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Mon, 18 Dec 2023 11:27:59 +0100
Subject: [PATCH 2/7] Update dynamic_linker.f90 test and clean up a bit

---
 clang/lib/Driver/ToolChains/CommonArgs.cpp | 22 ++
 flang/test/Driver/dynamic-linker.f90   |  6 +-
 2 files changed, 15 insertions(+), 13 deletions(-)

diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp 
b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 939a719c7c7e29..3b29e1bc75850f 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -1133,15 +1133,14 @@ static bool isWholeArchivePresent(const ArgList ) {
   return WholeArchiveActive;
 }
 
+/// Determine if driver is invoked to create a shared object library (-static)
 static bool isSharedLinkage(const ArgList ) {
-  bool FoundSharedFlag = false;
-  for (auto *Arg : Args.filtered(options::OPT_shared)) {
-if (Arg) {
-  FoundSharedFlag = true;
-}
-  }
+  return Args.hasArg(options::OPT_shared);
+}
 
-  return FoundSharedFlag;
+/// Determine if driver is invoked to create a static object library (-shared)
+static bool isStaticLinkage(const ArgList ) {
+  return Args.hasArg(options::OPT_static);
 }
 
 /// Add Fortran runtime libs for MSVC
@@ -1176,13 +1175,12 @@ static void addFortranRuntimeLibsMSVC(const ArgList 
,
 static void addFortranMain(const ToolChain , const ArgList ,
llvm::opt::ArgStringList ) {
   // 0. Shared-library linkage
-  // If we are attempting to link a shared library, we should not add
+  // If we are attempting to link a library, we should not add
   // -lFortran_main.a to the link line, as the `main` symbol is not
-  // required for a shared library and should also be provided by one
-  // of the translation units of the code that this shared library
+  // required for a library and should also be provided by one of
+  // the translation units of the code that this shared library
   // will be linked against eventually.
-  if (isSharedLinkage(Args)) {
-printf("MK: --> shared linkage, do not add -lFortranMain\n");
+  if (isSharedLinkage(Args) || isStaticLinkage(Args)) {
 return;
   }
 
diff --git a/flang/test/Driver/dynamic-linker.f90 
b/flang/test/Driver/dynamic-linker.f90
index 1cbd407d21ce09..069b51870c91ff 100644
--- a/flang/test/Driver/dynamic-linker.f90
+++ b/flang/test/Driver/dynamic-linker.f90
@@ -3,10 +3,12 @@
 
 ! RUN: %flang -### --target=x86_64-linux-gnu -rpath /path/to/dir -shared \
 ! RUN: -static %s 2>&1 | FileCheck \
-! RUN: --check-prefixes=GNU-LINKER-OPTIONS %s
+! RUN: --check-prefixes=GNU-LINKER-OPTIONS \
+! RUN: --implicit-check-not=GNU-LINKER-OPTIONS-NOT %s
 ! RUN: %flang -### --target=x86_64-windows-msvc -rpath /path/to/dir -shared \
 ! RUN: -static %s 2>&1 | FileCheck \
 ! RUN: --check-prefixes=MSVC-LINKER-OPTIONS %s
+! RUN: --implicit-check-not=MSVC-LINKER-OPTIONS-NOT %s
 ! RUN: %flang -### 

[flang] [clang] [flang][driver] Remove Fortain_main static library from linking stages (PR #75816)

[Michael Klemm via cfe-commits]

https://github.com/mjklemm updated 
https://github.com/llvm/llvm-project/pull/75816

>From 511f3a4537267284554bf6b33470a01d747b8a94 Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Sat, 16 Dec 2023 20:15:17 +0100
Subject: [PATCH 1/7] Remove -lFortran_main from the link line when -shared is
 present

---
 clang/lib/Driver/ToolChains/CommonArgs.cpp | 22 ++
 1 file changed, 22 insertions(+)

diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp 
b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 45901ee7157f77..5d525d3794ad1d 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -1133,6 +1133,17 @@ static bool isWholeArchivePresent(const ArgList ) {
   return WholeArchiveActive;
 }
 
+static bool isSharedLinkage(const ArgList ) {
+  bool FoundSharedFlag = false;
+  for (auto *Arg : Args.filtered(options::OPT_shared)) {
+if (Arg) {
+  FoundSharedFlag = true;
+}
+  }
+
+  return FoundSharedFlag;
+}
+
 /// Add Fortran runtime libs for MSVC
 static void addFortranRuntimeLibsMSVC(const ArgList ,
   llvm::opt::ArgStringList ) {
@@ -1164,6 +1175,17 @@ static void addFortranRuntimeLibsMSVC(const ArgList 
,
 // Add FortranMain runtime lib
 static void addFortranMain(const ToolChain , const ArgList ,
llvm::opt::ArgStringList ) {
+  // 0. Shared-library linkage
+  // If we are attempting to link a shared library, we should not add
+  // -lFortran_main.a to the link line, as the `main` symbol is not
+  // required for a shared library and should also be provided by one
+  // of the translation units of the code that this shared library
+  // will be linked against eventually.
+  if (isSharedLinkage(Args)) {
+printf("MK: --> shared linkage, do not add -lFortranMain\n");
+return;
+  }
+
   // 1. MSVC
   if (TC.getTriple().isKnownWindowsMSVCEnvironment()) {
 addFortranRuntimeLibsMSVC(Args, CmdArgs);

>From 930f2c447daa625d9e6019cd38d82b5750942f5d Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Mon, 18 Dec 2023 11:27:59 +0100
Subject: [PATCH 2/7] Update dynamic_linker.f90 test and clean up a bit

---
 clang/lib/Driver/ToolChains/CommonArgs.cpp | 22 ++
 flang/test/Driver/dynamic-linker.f90   |  8 ++--
 2 files changed, 16 insertions(+), 14 deletions(-)

diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp 
b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 5d525d3794ad1d..05ebd42829c95d 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -1133,15 +1133,14 @@ static bool isWholeArchivePresent(const ArgList ) {
   return WholeArchiveActive;
 }
 
+/// Determine if driver is invoked to create a shared object library (-static)
 static bool isSharedLinkage(const ArgList ) {
-  bool FoundSharedFlag = false;
-  for (auto *Arg : Args.filtered(options::OPT_shared)) {
-if (Arg) {
-  FoundSharedFlag = true;
-}
-  }
+  return Args.hasArg(options::OPT_shared);
+}
 
-  return FoundSharedFlag;
+/// Determine if driver is invoked to create a static object library (-shared)
+static bool isStaticLinkage(const ArgList ) {
+  return Args.hasArg(options::OPT_static);
 }
 
 /// Add Fortran runtime libs for MSVC
@@ -1176,13 +1175,12 @@ static void addFortranRuntimeLibsMSVC(const ArgList 
,
 static void addFortranMain(const ToolChain , const ArgList ,
llvm::opt::ArgStringList ) {
   // 0. Shared-library linkage
-  // If we are attempting to link a shared library, we should not add
+  // If we are attempting to link a library, we should not add
   // -lFortran_main.a to the link line, as the `main` symbol is not
-  // required for a shared library and should also be provided by one
-  // of the translation units of the code that this shared library
+  // required for a library and should also be provided by one of
+  // the translation units of the code that this shared library
   // will be linked against eventually.
-  if (isSharedLinkage(Args)) {
-printf("MK: --> shared linkage, do not add -lFortranMain\n");
+  if (isSharedLinkage(Args) || isStaticLinkage(Args)) {
 return;
   }
 
diff --git a/flang/test/Driver/dynamic-linker.f90 
b/flang/test/Driver/dynamic-linker.f90
index df119c22a2ea51..af07e2483f93fa 100644
--- a/flang/test/Driver/dynamic-linker.f90
+++ b/flang/test/Driver/dynamic-linker.f90
@@ -3,18 +3,22 @@
 
 ! RUN: %flang -### --target=x86_64-linux-gnu -rpath /path/to/dir -shared \
 ! RUN: -static %s 2>&1 | FileCheck \
-! RUN: --check-prefixes=GNU-LINKER-OPTIONS %s
+! RUN: --check-prefixes=GNU-LINKER-OPTIONS \
+! RUN: --implicit-check-not=GNU-LINKER-OPTIONS-NOT %s
 ! RUN: %flang -### --target=x86_64-windows-msvc -rpath /path/to/dir -shared \
 ! RUN: -static %s 2>&1 | FileCheck \
-! RUN: --check-prefixes=MSVC-LINKER-OPTIONS %s
+! RUN: --check-prefixes=MSVC-LINKER-OPTIONS \
+! RUN: 

[flang] [clang] [flang][driver] Remove Fortain_main static library from linking stages (PR #75816)

[Michael Klemm via cfe-commits]

@@ -163,6 +163,62 @@ forward compiler options to the frontend driver, 
`flang-new -fc1`.
 You can read more on the design of `clangDriver` in Clang's [Driver Design &
 Internals](https://clang.llvm.org/docs/DriverInternals.html).
 
+## Linker Driver
+When used as a linker, Flang's frontend driver assembles the command line for 
an
+external linker command (e.g., LLVM's `lld`) and invokes it to create the final
+executable by linking static and shared libraries together with all the
+translation units supplied as object files.
+
+By default, the Flang linker driver adds several libraries to the linker
+invocation to make sure that all entrypoints for program start
+(Fortran's program unit) and runtime routines can be resolved by the linker.
+
+An abridged example (only showing the Fortran specific linker flags, omission
+indicated by `[...]`) for such a linker invocation on a Linux system would look
+like this:
+
+```
+$ flang -v -o example example.o
+"/usr/bin/ld" [...] example.o [...] "--whole-archive" "-lFortran_main"
+"--no-whole-archive" "-lFortranRuntime" "-lFortranDecimal" [...]
+```
+
+The automatically added libraries are:
+
+* `Fortran_main`: Provides the main entry point `main` that then invokes
+  `_QQmain` with the Fortran program unit.  This library has a dependency to
+  the `FortranRuntime` library.
+* `FortranRuntime`: Provides most of the Flang runtime library.
+* `FortranDecimal`: Provides operations for decimal numbers.
+
+The default is that, when using Flang as the linker, one of the Fortran
+translation units provides the program unit and therefore it is assumed that
+Fortran is the main code part (calling into C/C++ routines via `BIND (C)`
+interfaces).  When composing the linker commandline, Flang uses
+`--whole-archive` and `--no-whole-archive` (Windows: `/WHOLEARCHIVE:`,
+Darwin & AIX: *not implemented yet*) to make sure that all for `Fortran_main`
+is processed by the linker.  This is done to issue a proper error message when
+multiple definitions of `main` occur.  This happens, for instance, when linking
+a code that has a Fortran program unit with a C/C++ code that also defines a
+`main` function.  A user may be required to explicitly provide the C++ runtime
+libraries at link time (e.g., via `-lstdc++` for STL)
+
+If the code is C/C++ based and invokes Fortran routines, one can either use 
Clang
+for Flang as the linker driver.  If Clang is used, it will automatically all
+required runtime libraries needed by C++ (e.g., for STL) to the linker 
invocation.
+In this case, one has to explicitly provide the Fortran runtime libraries
+`FortranRuntime` and/or `FortranDecimal`.  An alternative is to use Flang to 
link
+and use the `-fno-fortran-main` flag.  This flag removes
+`Fortran_main` from the linker stage and hence requires one of the C/C++
+translation units to provide a definition of the `main` function. In this case,
+it may be required to explicitly supply C++ runtime libraries as mentioned 
above.
+
+When creating shared or static libraries, `Fortran_main` is automatically

mjklemm wrote:

Applied!  Thanks for the rewording!

https://github.com/llvm/llvm-project/pull/75816
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[flang] [clang] [flang][driver] Remove Fortain_main static library from linking stages (PR #75816)

[Michael Klemm via cfe-commits]

@@ -163,6 +163,62 @@ forward compiler options to the frontend driver, 
`flang-new -fc1`.
 You can read more on the design of `clangDriver` in Clang's [Driver Design &
 Internals](https://clang.llvm.org/docs/DriverInternals.html).
 
+## Linker Driver
+When used as a linker, Flang's frontend driver assembles the command line for 
an
+external linker command (e.g., LLVM's `lld`) and invokes it to create the final
+executable by linking static and shared libraries together with all the
+translation units supplied as object files.
+
+By default, the Flang linker driver adds several libraries to the linker
+invocation to make sure that all entrypoints for program start
+(Fortran's program unit) and runtime routines can be resolved by the linker.
+
+An abridged example (only showing the Fortran specific linker flags, omission
+indicated by `[...]`) for such a linker invocation on a Linux system would look
+like this:
+
+```
+$ flang -v -o example example.o
+"/usr/bin/ld" [...] example.o [...] "--whole-archive" "-lFortran_main"
+"--no-whole-archive" "-lFortranRuntime" "-lFortranDecimal" [...]
+```
+
+The automatically added libraries are:
+
+* `Fortran_main`: Provides the main entry point `main` that then invokes
+  `_QQmain` with the Fortran program unit.  This library has a dependency to
+  the `FortranRuntime` library.
+* `FortranRuntime`: Provides most of the Flang runtime library.
+* `FortranDecimal`: Provides operations for decimal numbers.
+
+The default is that, when using Flang as the linker, one of the Fortran
+translation units provides the program unit and therefore it is assumed that
+Fortran is the main code part (calling into C/C++ routines via `BIND (C)`
+interfaces).  When composing the linker commandline, Flang uses
+`--whole-archive` and `--no-whole-archive` (Windows: `/WHOLEARCHIVE:`,
+Darwin & AIX: *not implemented yet*) to make sure that all for `Fortran_main`
+is processed by the linker.  This is done to issue a proper error message when
+multiple definitions of `main` occur.  This happens, for instance, when linking
+a code that has a Fortran program unit with a C/C++ code that also defines a
+`main` function.  A user may be required to explicitly provide the C++ runtime
+libraries at link time (e.g., via `-lstdc++` for STL)
+
+If the code is C/C++ based and invokes Fortran routines, one can either use 
Clang
+for Flang as the linker driver.  If Clang is used, it will automatically all
+required runtime libraries needed by C++ (e.g., for STL) to the linker 
invocation.

mjklemm wrote:

I treated clang and clang++ the same here, as they seem to have reasonable 
logic to figure out if C or C++ is compiled and linked,

https://github.com/llvm/llvm-project/pull/75816
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[flang] [clang] [flang][driver] Remove Fortain_main static library from linking stages (PR #75816)

[Michael Klemm via cfe-commits]

https://github.com/mjklemm updated 
https://github.com/llvm/llvm-project/pull/75816

>From 511f3a4537267284554bf6b33470a01d747b8a94 Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Sat, 16 Dec 2023 20:15:17 +0100
Subject: [PATCH 1/6] Remove -lFortran_main from the link line when -shared is
 present

---
 clang/lib/Driver/ToolChains/CommonArgs.cpp | 22 ++
 1 file changed, 22 insertions(+)

diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp 
b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 45901ee7157f77..5d525d3794ad1d 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -1133,6 +1133,17 @@ static bool isWholeArchivePresent(const ArgList ) {
   return WholeArchiveActive;
 }
 
+static bool isSharedLinkage(const ArgList ) {
+  bool FoundSharedFlag = false;
+  for (auto *Arg : Args.filtered(options::OPT_shared)) {
+if (Arg) {
+  FoundSharedFlag = true;
+}
+  }
+
+  return FoundSharedFlag;
+}
+
 /// Add Fortran runtime libs for MSVC
 static void addFortranRuntimeLibsMSVC(const ArgList ,
   llvm::opt::ArgStringList ) {
@@ -1164,6 +1175,17 @@ static void addFortranRuntimeLibsMSVC(const ArgList 
,
 // Add FortranMain runtime lib
 static void addFortranMain(const ToolChain , const ArgList ,
llvm::opt::ArgStringList ) {
+  // 0. Shared-library linkage
+  // If we are attempting to link a shared library, we should not add
+  // -lFortran_main.a to the link line, as the `main` symbol is not
+  // required for a shared library and should also be provided by one
+  // of the translation units of the code that this shared library
+  // will be linked against eventually.
+  if (isSharedLinkage(Args)) {
+printf("MK: --> shared linkage, do not add -lFortranMain\n");
+return;
+  }
+
   // 1. MSVC
   if (TC.getTriple().isKnownWindowsMSVCEnvironment()) {
 addFortranRuntimeLibsMSVC(Args, CmdArgs);

>From 930f2c447daa625d9e6019cd38d82b5750942f5d Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Mon, 18 Dec 2023 11:27:59 +0100
Subject: [PATCH 2/6] Update dynamic_linker.f90 test and clean up a bit

---
 clang/lib/Driver/ToolChains/CommonArgs.cpp | 22 ++
 flang/test/Driver/dynamic-linker.f90   |  8 ++--
 2 files changed, 16 insertions(+), 14 deletions(-)

diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp 
b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 5d525d3794ad1d..05ebd42829c95d 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -1133,15 +1133,14 @@ static bool isWholeArchivePresent(const ArgList ) {
   return WholeArchiveActive;
 }
 
+/// Determine if driver is invoked to create a shared object library (-static)
 static bool isSharedLinkage(const ArgList ) {
-  bool FoundSharedFlag = false;
-  for (auto *Arg : Args.filtered(options::OPT_shared)) {
-if (Arg) {
-  FoundSharedFlag = true;
-}
-  }
+  return Args.hasArg(options::OPT_shared);
+}
 
-  return FoundSharedFlag;
+/// Determine if driver is invoked to create a static object library (-shared)
+static bool isStaticLinkage(const ArgList ) {
+  return Args.hasArg(options::OPT_static);
 }
 
 /// Add Fortran runtime libs for MSVC
@@ -1176,13 +1175,12 @@ static void addFortranRuntimeLibsMSVC(const ArgList 
,
 static void addFortranMain(const ToolChain , const ArgList ,
llvm::opt::ArgStringList ) {
   // 0. Shared-library linkage
-  // If we are attempting to link a shared library, we should not add
+  // If we are attempting to link a library, we should not add
   // -lFortran_main.a to the link line, as the `main` symbol is not
-  // required for a shared library and should also be provided by one
-  // of the translation units of the code that this shared library
+  // required for a library and should also be provided by one of
+  // the translation units of the code that this shared library
   // will be linked against eventually.
-  if (isSharedLinkage(Args)) {
-printf("MK: --> shared linkage, do not add -lFortranMain\n");
+  if (isSharedLinkage(Args) || isStaticLinkage(Args)) {
 return;
   }
 
diff --git a/flang/test/Driver/dynamic-linker.f90 
b/flang/test/Driver/dynamic-linker.f90
index df119c22a2ea51..af07e2483f93fa 100644
--- a/flang/test/Driver/dynamic-linker.f90
+++ b/flang/test/Driver/dynamic-linker.f90
@@ -3,18 +3,22 @@
 
 ! RUN: %flang -### --target=x86_64-linux-gnu -rpath /path/to/dir -shared \
 ! RUN: -static %s 2>&1 | FileCheck \
-! RUN: --check-prefixes=GNU-LINKER-OPTIONS %s
+! RUN: --check-prefixes=GNU-LINKER-OPTIONS \
+! RUN: --implicit-check-not=GNU-LINKER-OPTIONS-NOT %s
 ! RUN: %flang -### --target=x86_64-windows-msvc -rpath /path/to/dir -shared \
 ! RUN: -static %s 2>&1 | FileCheck \
-! RUN: --check-prefixes=MSVC-LINKER-OPTIONS %s
+! RUN: --check-prefixes=MSVC-LINKER-OPTIONS \
+! RUN: 

[clang] [flang] [flang][driver] Remove Fortain_main static library from linking stages (PR #75816)

[Michael Klemm via cfe-commits]

@@ -163,6 +163,40 @@ forward compiler options to the frontend driver, 
`flang-new -fc1`.
 You can read more on the design of `clangDriver` in Clang's [Driver Design &
 Internals](https://clang.llvm.org/docs/DriverInternals.html).
 
+## Linker Driver
+When used as a linker, Flang's frontend driver assembles the command line for 
an
+external linker command (e.g., LLVM's `lld`) and invokes it to create the final
+executable by linking static and shared libraries together with all the
+translation units supplied as object files.
+
+By default, the Flang linker driver adds several libraries to the linker
+invocation to make sure that all entrypoints for program start
+(Fortran's program unit) and runtime routines can be resolved by the linker.
+The libraries are:
+
+* `Fortran_main`: Provides the main entry point `main` that then invokes
+  `_QQmain` with the Fortran program unit.  This library has a dependency to
+  the `FortranRuntime` library.
+* `FortranRuntime`: Provides most of the Flang runtime library.
+* `FortranDecimal`: Provides operations for decimal numbers.
+
+The default is that, when using Flang as the linker, one of the Fortran
+translation units provides the program unit and therefore it is assumed that
+Fortran is the main code part (calling into C/C++ routines via `BIND
+(C)` interfaces).  When composing the linker commandline, Flang uses
+`--whole-archive` and `--no-whole-archive` (Windows: `/WHOLEARCHIVE:`,
+Darwin: *not implemented yet*) to make sure that all for `Fortran_main` is
+processed by the linker.  This is done to issue a proper error message when
+multiple definitions of `main` occur.  This happens, for instance, when linking
+a code that has a Fortran program unit with a C/C++ code that also defines a
+`main` function.
+
+If the code is C/C++ based and invokes Fortran routines, either use Clang as 
the
+linker driver (supplying `FortranRuntime` and/or `FortranDecimal` to the linker

mjklemm wrote:

I have tried to clarify a bit what the two choices are when using Clang vs 
Flang to link a program. Is this better now?

https://github.com/llvm/llvm-project/pull/75816
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[clang] [flang] [flang][driver] Remove Fortain_main static library from linking stages (PR #75816)

[Michael Klemm via cfe-commits]

@@ -163,6 +163,40 @@ forward compiler options to the frontend driver, 
`flang-new -fc1`.
 You can read more on the design of `clangDriver` in Clang's [Driver Design &
 Internals](https://clang.llvm.org/docs/DriverInternals.html).
 
+## Linker Driver

mjklemm wrote:

I have tried to capture this now.

https://github.com/llvm/llvm-project/pull/75816
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[clang] [flang] [flang][driver] Remove Fortain_main static library from linking stages (PR #75816)

[Michael Klemm via cfe-commits]

https://github.com/mjklemm updated 
https://github.com/llvm/llvm-project/pull/75816

>From 511f3a4537267284554bf6b33470a01d747b8a94 Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Sat, 16 Dec 2023 20:15:17 +0100
Subject: [PATCH 1/5] Remove -lFortran_main from the link line when -shared is
 present

---
 clang/lib/Driver/ToolChains/CommonArgs.cpp | 22 ++
 1 file changed, 22 insertions(+)

diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp 
b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 45901ee7157f77..5d525d3794ad1d 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -1133,6 +1133,17 @@ static bool isWholeArchivePresent(const ArgList ) {
   return WholeArchiveActive;
 }
 
+static bool isSharedLinkage(const ArgList ) {
+  bool FoundSharedFlag = false;
+  for (auto *Arg : Args.filtered(options::OPT_shared)) {
+if (Arg) {
+  FoundSharedFlag = true;
+}
+  }
+
+  return FoundSharedFlag;
+}
+
 /// Add Fortran runtime libs for MSVC
 static void addFortranRuntimeLibsMSVC(const ArgList ,
   llvm::opt::ArgStringList ) {
@@ -1164,6 +1175,17 @@ static void addFortranRuntimeLibsMSVC(const ArgList 
,
 // Add FortranMain runtime lib
 static void addFortranMain(const ToolChain , const ArgList ,
llvm::opt::ArgStringList ) {
+  // 0. Shared-library linkage
+  // If we are attempting to link a shared library, we should not add
+  // -lFortran_main.a to the link line, as the `main` symbol is not
+  // required for a shared library and should also be provided by one
+  // of the translation units of the code that this shared library
+  // will be linked against eventually.
+  if (isSharedLinkage(Args)) {
+printf("MK: --> shared linkage, do not add -lFortranMain\n");
+return;
+  }
+
   // 1. MSVC
   if (TC.getTriple().isKnownWindowsMSVCEnvironment()) {
 addFortranRuntimeLibsMSVC(Args, CmdArgs);

>From 930f2c447daa625d9e6019cd38d82b5750942f5d Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Mon, 18 Dec 2023 11:27:59 +0100
Subject: [PATCH 2/5] Update dynamic_linker.f90 test and clean up a bit

---
 clang/lib/Driver/ToolChains/CommonArgs.cpp | 22 ++
 flang/test/Driver/dynamic-linker.f90   |  8 ++--
 2 files changed, 16 insertions(+), 14 deletions(-)

diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp 
b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 5d525d3794ad1d..05ebd42829c95d 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -1133,15 +1133,14 @@ static bool isWholeArchivePresent(const ArgList ) {
   return WholeArchiveActive;
 }
 
+/// Determine if driver is invoked to create a shared object library (-static)
 static bool isSharedLinkage(const ArgList ) {
-  bool FoundSharedFlag = false;
-  for (auto *Arg : Args.filtered(options::OPT_shared)) {
-if (Arg) {
-  FoundSharedFlag = true;
-}
-  }
+  return Args.hasArg(options::OPT_shared);
+}
 
-  return FoundSharedFlag;
+/// Determine if driver is invoked to create a static object library (-shared)
+static bool isStaticLinkage(const ArgList ) {
+  return Args.hasArg(options::OPT_static);
 }
 
 /// Add Fortran runtime libs for MSVC
@@ -1176,13 +1175,12 @@ static void addFortranRuntimeLibsMSVC(const ArgList 
,
 static void addFortranMain(const ToolChain , const ArgList ,
llvm::opt::ArgStringList ) {
   // 0. Shared-library linkage
-  // If we are attempting to link a shared library, we should not add
+  // If we are attempting to link a library, we should not add
   // -lFortran_main.a to the link line, as the `main` symbol is not
-  // required for a shared library and should also be provided by one
-  // of the translation units of the code that this shared library
+  // required for a library and should also be provided by one of
+  // the translation units of the code that this shared library
   // will be linked against eventually.
-  if (isSharedLinkage(Args)) {
-printf("MK: --> shared linkage, do not add -lFortranMain\n");
+  if (isSharedLinkage(Args) || isStaticLinkage(Args)) {
 return;
   }
 
diff --git a/flang/test/Driver/dynamic-linker.f90 
b/flang/test/Driver/dynamic-linker.f90
index df119c22a2ea51..af07e2483f93fa 100644
--- a/flang/test/Driver/dynamic-linker.f90
+++ b/flang/test/Driver/dynamic-linker.f90
@@ -3,18 +3,22 @@
 
 ! RUN: %flang -### --target=x86_64-linux-gnu -rpath /path/to/dir -shared \
 ! RUN: -static %s 2>&1 | FileCheck \
-! RUN: --check-prefixes=GNU-LINKER-OPTIONS %s
+! RUN: --check-prefixes=GNU-LINKER-OPTIONS \
+! RUN: --implicit-check-not=GNU-LINKER-OPTIONS-NOT %s
 ! RUN: %flang -### --target=x86_64-windows-msvc -rpath /path/to/dir -shared \
 ! RUN: -static %s 2>&1 | FileCheck \
-! RUN: --check-prefixes=MSVC-LINKER-OPTIONS %s
+! RUN: --check-prefixes=MSVC-LINKER-OPTIONS \
+! RUN: 

[flang] [clang] [Flang] remove whole-archive option for AIX linker (PR #76039)

[Michael Klemm via cfe-commits]

https://github.com/mjklemm approved this pull request.

LGTM, but please add to the TODO comment in line 1177 that for AIX a better 
solution needs to be found.

https://github.com/llvm/llvm-project/pull/76039
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[flang] [clang] [flang][driver] Remove Fortain_main static library from linking stages (PR #75816)

[Michael Klemm via cfe-commits]

@@ -163,6 +163,40 @@ forward compiler options to the frontend driver, 
`flang-new -fc1`.
 You can read more on the design of `clangDriver` in Clang's [Driver Design &
 Internals](https://clang.llvm.org/docs/DriverInternals.html).
 
+## Linker Driver

mjklemm wrote:

Good suggestion!

https://github.com/llvm/llvm-project/pull/75816
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[flang] [clang] [flang][driver] Remove Fortain_main static library from linking stages (PR #75816)

[Michael Klemm via cfe-commits]

@@ -163,6 +163,40 @@ forward compiler options to the frontend driver, 
`flang-new -fc1`.
 You can read more on the design of `clangDriver` in Clang's [Driver Design &
 Internals](https://clang.llvm.org/docs/DriverInternals.html).
 
+## Linker Driver
+When used as a linker, Flang's frontend driver assembles the command line for 
an
+external linker command (e.g., LLVM's `lld`) and invokes it to create the final
+executable by linking static and shared libraries together with all the
+translation units supplied as object files.
+
+By default, the Flang linker driver adds several libraries to the linker
+invocation to make sure that all entrypoints for program start
+(Fortran's program unit) and runtime routines can be resolved by the linker.
+The libraries are:
+
+* `Fortran_main`: Provides the main entry point `main` that then invokes
+  `_QQmain` with the Fortran program unit.  This library has a dependency to
+  the `FortranRuntime` library.
+* `FortranRuntime`: Provides most of the Flang runtime library.
+* `FortranDecimal`: Provides operations for decimal numbers.
+
+The default is that, when using Flang as the linker, one of the Fortran
+translation units provides the program unit and therefore it is assumed that
+Fortran is the main code part (calling into C/C++ routines via `BIND
+(C)` interfaces).  When composing the linker commandline, Flang uses
+`--whole-archive` and `--no-whole-archive` (Windows: `/WHOLEARCHIVE:`,
+Darwin: *not implemented yet*) to make sure that all for `Fortran_main` is
+processed by the linker.  This is done to issue a proper error message when
+multiple definitions of `main` occur.  This happens, for instance, when linking
+a code that has a Fortran program unit with a C/C++ code that also defines a
+`main` function.
+
+If the code is C/C++ based and invokes Fortran routines, either use Clang as 
the
+linker driver (supplying `FortranRuntime` and/or `FortranDecimal` to the linker

mjklemm wrote:

> It could be updated, but that should probably be raised on Discourse or in 
> the community call. Having said, documenting this is long overdue and I am 
> super grateful that Michael is doing this for us 

I fully agree.  The good thing is: it's not defined in any (ISO) standard, so 
we can do whatever we like and what we think is useful behavior in the end.  
I'd like to note that the introduction of `-fno-fortran-main` can still be 
useful with a behavior that is similar to GFortran (emitting the actual `main` 
code in the translation unit with a program statement), but would then turn 
`-fno-fortran-main` flag into a more corner-case, expert type flag.

I'd suggest to get current behavior cleanly merged for the 18.0 branch and then 
re-think this somewhat more for the 19.0 release and the future.  At least now, 
we will have documented and well-defined behavior.  If it's the right one, we 
can debate. :-)

https://github.com/llvm/llvm-project/pull/75816
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[flang] [clang] [flang][driver] Remove Fortain_main static library from linking stages (PR #75816)

[Michael Klemm via cfe-commits]

@@ -163,6 +163,40 @@ forward compiler options to the frontend driver, 
`flang-new -fc1`.
 You can read more on the design of `clangDriver` in Clang's [Driver Design &
 Internals](https://clang.llvm.org/docs/DriverInternals.html).
 
+## Linker Driver
+When used as a linker, Flang's frontend driver assembles the command line for 
an
+external linker command (e.g., LLVM's `lld`) and invokes it to create the final
+executable by linking static and shared libraries together with all the
+translation units supplied as object files.
+
+By default, the Flang linker driver adds several libraries to the linker
+invocation to make sure that all entrypoints for program start
+(Fortran's program unit) and runtime routines can be resolved by the linker.
+The libraries are:
+
+* `Fortran_main`: Provides the main entry point `main` that then invokes
+  `_QQmain` with the Fortran program unit.  This library has a dependency to
+  the `FortranRuntime` library.
+* `FortranRuntime`: Provides most of the Flang runtime library.
+* `FortranDecimal`: Provides operations for decimal numbers.
+
+The default is that, when using Flang as the linker, one of the Fortran
+translation units provides the program unit and therefore it is assumed that
+Fortran is the main code part (calling into C/C++ routines via `BIND
+(C)` interfaces).  When composing the linker commandline, Flang uses
+`--whole-archive` and `--no-whole-archive` (Windows: `/WHOLEARCHIVE:`,
+Darwin: *not implemented yet*) to make sure that all for `Fortran_main` is
+processed by the linker.  This is done to issue a proper error message when
+multiple definitions of `main` occur.  This happens, for instance, when linking
+a code that has a Fortran program unit with a C/C++ code that also defines a
+`main` function.
+
+If the code is C/C++ based and invokes Fortran routines, either use Clang as 
the
+linker driver (supplying `FortranRuntime` and/or `FortranDecimal` to the linker

mjklemm wrote:

> I think this requirement of using Clang as the linker driver if the `main` is 
> C changes the usability for users coming from XLF or gfortran.

I can reword this.  There are two options: either do C/C++ linkage and supply 
Fortran libraries or do Fortran linkage and supply C/C++ libraries.  Either way 
is equally difficult at this point.

> I think the fundamental question is why Fortran_main.c is inserting a "fake" 
> main on the Fortran side when there is not user defined main in Fortrran code.

This was inherited from Classic Flang and is also done by other compilers 
(e.g., Intel).

> Is it possible to only creating a main when users define one in Fortran code?

That would also be possible.  I guess the compiler could generate all of `main` 
in IR and emit it.  That's what GFortran does.


https://github.com/llvm/llvm-project/pull/75816
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[clang] [flang] [flang][driver] Remove Fortain_main static library from linking stages (PR #75816)

[Michael Klemm via cfe-commits]

@@ -163,6 +163,40 @@ forward compiler options to the frontend driver, 
`flang-new -fc1`.
 You can read more on the design of `clangDriver` in Clang's [Driver Design &
 Internals](https://clang.llvm.org/docs/DriverInternals.html).
 
+## Linker Driver
+When used as a linker, Flang's frontend driver assembles the command line for 
an
+external linker command (e.g., LLVM's `lld`) and invokes it to create the final
+executable by linking static and shared libraries together with all the
+translation units supplied as object files.
+
+By default, the Flang linker driver adds several libraries to the linker
+invocation to make sure that all entrypoints for program start
+(Fortran's program unit) and runtime routines can be resolved by the linker.
+The libraries are:
+
+* `Fortran_main`: Provides the main entry point `main` that then invokes
+  `_QQmain` with the Fortran program unit.  This library has a dependency to
+  the `FortranRuntime` library.
+* `FortranRuntime`: Provides most of the Flang runtime library.
+* `FortranDecimal`: Provides operations for decimal numbers.
+
+The default is that, when using Flang as the linker, one of the Fortran
+translation units provides the program unit and therefore it is assumed that
+Fortran is the main code part (calling into C/C++ routines via `BIND
+(C)` interfaces).  When composing the linker commandline, Flang uses
+`--whole-archive` and `--no-whole-archive` (Windows: `/WHOLEARCHIVE:`,
+Darwin: *not implemented yet*) to make sure that all for `Fortran_main` is
+processed by the linker.  This is done to issue a proper error message when
+multiple definitions of `main` occur.  This happens, for instance, when linking
+a code that has a Fortran program unit with a C/C++ code that also defines a
+`main` function.
+
+If the code is C/C++ based and invokes Fortran routines, either use Clang as 
the
+linker driver (supplying `FortranRuntime` and/or `FortranDecimal` to the linker

mjklemm wrote:

Yes.  Similar to what one would have to do if not using an MPI wrapper to 
compile an MPI program.  I'll make this is a bit clearer.

https://github.com/llvm/llvm-project/pull/75816
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[clang] [flang] [flang][driver] Remove Fortain_main static library from linking stages (PR #75816)

[Michael Klemm via cfe-commits]

mjklemm wrote:

@banach-space How did you draw the pictures in the MD file that I'm changing?  
If you have some sort of source file, I can try to add a nice chart to the 
explanation, I'm adding.

https://github.com/llvm/llvm-project/pull/75816
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[flang] [clang] [flang][Driver] Let the linker fail on multiple definitions of main() (PR #73124)

[Michael Klemm via cfe-commits]

mjklemm wrote:

> May be I missed it when reading through the comments of this PR, why there is 
> a definition of `main()` being generated on the Fortran side when the Fortran 
> sources are procedures or modules?

It was always generated before, but the bug was hidden by the linker doing the 
right thing by incidence.  I have fixed that so that such an error does no 
longer unnoticed.



https://github.com/llvm/llvm-project/pull/73124
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[flang] [clang] [flang][driver] Remove Fortain_main static library from linking stages (PR #75816)

[Michael Klemm via cfe-commits]

mjklemm wrote:

> I would probably create a section on building executables and just mention 
> that 3 runtime libs will be linked auto-magically. Unless somebody uses 
> `-fno-fortran-main` ;-) Make it as short or as long as you prefer - your 
> contribution is greatly appreciated  :)

If have written up a first draft.  Please have a look and let me know what you 
think.

https://github.com/llvm/llvm-project/pull/75816
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[clang] [flang] [flang][driver] Remove Fortain_main static library from linking stages (PR #75816)

[Michael Klemm via cfe-commits]

https://github.com/mjklemm updated 
https://github.com/llvm/llvm-project/pull/75816

>From 511f3a4537267284554bf6b33470a01d747b8a94 Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Sat, 16 Dec 2023 20:15:17 +0100
Subject: [PATCH 1/4] Remove -lFortran_main from the link line when -shared is
 present

---
 clang/lib/Driver/ToolChains/CommonArgs.cpp | 22 ++
 1 file changed, 22 insertions(+)

diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp 
b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 45901ee7157f77..5d525d3794ad1d 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -1133,6 +1133,17 @@ static bool isWholeArchivePresent(const ArgList ) {
   return WholeArchiveActive;
 }
 
+static bool isSharedLinkage(const ArgList ) {
+  bool FoundSharedFlag = false;
+  for (auto *Arg : Args.filtered(options::OPT_shared)) {
+if (Arg) {
+  FoundSharedFlag = true;
+}
+  }
+
+  return FoundSharedFlag;
+}
+
 /// Add Fortran runtime libs for MSVC
 static void addFortranRuntimeLibsMSVC(const ArgList ,
   llvm::opt::ArgStringList ) {
@@ -1164,6 +1175,17 @@ static void addFortranRuntimeLibsMSVC(const ArgList 
,
 // Add FortranMain runtime lib
 static void addFortranMain(const ToolChain , const ArgList ,
llvm::opt::ArgStringList ) {
+  // 0. Shared-library linkage
+  // If we are attempting to link a shared library, we should not add
+  // -lFortran_main.a to the link line, as the `main` symbol is not
+  // required for a shared library and should also be provided by one
+  // of the translation units of the code that this shared library
+  // will be linked against eventually.
+  if (isSharedLinkage(Args)) {
+printf("MK: --> shared linkage, do not add -lFortranMain\n");
+return;
+  }
+
   // 1. MSVC
   if (TC.getTriple().isKnownWindowsMSVCEnvironment()) {
 addFortranRuntimeLibsMSVC(Args, CmdArgs);

>From 930f2c447daa625d9e6019cd38d82b5750942f5d Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Mon, 18 Dec 2023 11:27:59 +0100
Subject: [PATCH 2/4] Update dynamic_linker.f90 test and clean up a bit

---
 clang/lib/Driver/ToolChains/CommonArgs.cpp | 22 ++
 flang/test/Driver/dynamic-linker.f90   |  8 ++--
 2 files changed, 16 insertions(+), 14 deletions(-)

diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp 
b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 5d525d3794ad1d..05ebd42829c95d 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -1133,15 +1133,14 @@ static bool isWholeArchivePresent(const ArgList ) {
   return WholeArchiveActive;
 }
 
+/// Determine if driver is invoked to create a shared object library (-static)
 static bool isSharedLinkage(const ArgList ) {
-  bool FoundSharedFlag = false;
-  for (auto *Arg : Args.filtered(options::OPT_shared)) {
-if (Arg) {
-  FoundSharedFlag = true;
-}
-  }
+  return Args.hasArg(options::OPT_shared);
+}
 
-  return FoundSharedFlag;
+/// Determine if driver is invoked to create a static object library (-shared)
+static bool isStaticLinkage(const ArgList ) {
+  return Args.hasArg(options::OPT_static);
 }
 
 /// Add Fortran runtime libs for MSVC
@@ -1176,13 +1175,12 @@ static void addFortranRuntimeLibsMSVC(const ArgList 
,
 static void addFortranMain(const ToolChain , const ArgList ,
llvm::opt::ArgStringList ) {
   // 0. Shared-library linkage
-  // If we are attempting to link a shared library, we should not add
+  // If we are attempting to link a library, we should not add
   // -lFortran_main.a to the link line, as the `main` symbol is not
-  // required for a shared library and should also be provided by one
-  // of the translation units of the code that this shared library
+  // required for a library and should also be provided by one of
+  // the translation units of the code that this shared library
   // will be linked against eventually.
-  if (isSharedLinkage(Args)) {
-printf("MK: --> shared linkage, do not add -lFortranMain\n");
+  if (isSharedLinkage(Args) || isStaticLinkage(Args)) {
 return;
   }
 
diff --git a/flang/test/Driver/dynamic-linker.f90 
b/flang/test/Driver/dynamic-linker.f90
index df119c22a2ea51..af07e2483f93fa 100644
--- a/flang/test/Driver/dynamic-linker.f90
+++ b/flang/test/Driver/dynamic-linker.f90
@@ -3,18 +3,22 @@
 
 ! RUN: %flang -### --target=x86_64-linux-gnu -rpath /path/to/dir -shared \
 ! RUN: -static %s 2>&1 | FileCheck \
-! RUN: --check-prefixes=GNU-LINKER-OPTIONS %s
+! RUN: --check-prefixes=GNU-LINKER-OPTIONS \
+! RUN: --implicit-check-not=GNU-LINKER-OPTIONS-NOT %s
 ! RUN: %flang -### --target=x86_64-windows-msvc -rpath /path/to/dir -shared \
 ! RUN: -static %s 2>&1 | FileCheck \
-! RUN: --check-prefixes=MSVC-LINKER-OPTIONS %s
+! RUN: --check-prefixes=MSVC-LINKER-OPTIONS \
+! RUN: 

[clang] [flang] [flang][driver] Remove Fortain_main static library from linking stages (PR #75816)

[Michael Klemm via cfe-commits]

https://github.com/mjklemm updated 
https://github.com/llvm/llvm-project/pull/75816

>From 511f3a4537267284554bf6b33470a01d747b8a94 Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Sat, 16 Dec 2023 20:15:17 +0100
Subject: [PATCH 1/3] Remove -lFortran_main from the link line when -shared is
 present

---
 clang/lib/Driver/ToolChains/CommonArgs.cpp | 22 ++
 1 file changed, 22 insertions(+)

diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp 
b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 45901ee7157f77..5d525d3794ad1d 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -1133,6 +1133,17 @@ static bool isWholeArchivePresent(const ArgList ) {
   return WholeArchiveActive;
 }
 
+static bool isSharedLinkage(const ArgList ) {
+  bool FoundSharedFlag = false;
+  for (auto *Arg : Args.filtered(options::OPT_shared)) {
+if (Arg) {
+  FoundSharedFlag = true;
+}
+  }
+
+  return FoundSharedFlag;
+}
+
 /// Add Fortran runtime libs for MSVC
 static void addFortranRuntimeLibsMSVC(const ArgList ,
   llvm::opt::ArgStringList ) {
@@ -1164,6 +1175,17 @@ static void addFortranRuntimeLibsMSVC(const ArgList 
,
 // Add FortranMain runtime lib
 static void addFortranMain(const ToolChain , const ArgList ,
llvm::opt::ArgStringList ) {
+  // 0. Shared-library linkage
+  // If we are attempting to link a shared library, we should not add
+  // -lFortran_main.a to the link line, as the `main` symbol is not
+  // required for a shared library and should also be provided by one
+  // of the translation units of the code that this shared library
+  // will be linked against eventually.
+  if (isSharedLinkage(Args)) {
+printf("MK: --> shared linkage, do not add -lFortranMain\n");
+return;
+  }
+
   // 1. MSVC
   if (TC.getTriple().isKnownWindowsMSVCEnvironment()) {
 addFortranRuntimeLibsMSVC(Args, CmdArgs);

>From 930f2c447daa625d9e6019cd38d82b5750942f5d Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Mon, 18 Dec 2023 11:27:59 +0100
Subject: [PATCH 2/3] Update dynamic_linker.f90 test and clean up a bit

---
 clang/lib/Driver/ToolChains/CommonArgs.cpp | 22 ++
 flang/test/Driver/dynamic-linker.f90   |  8 ++--
 2 files changed, 16 insertions(+), 14 deletions(-)

diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp 
b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 5d525d3794ad1d..05ebd42829c95d 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -1133,15 +1133,14 @@ static bool isWholeArchivePresent(const ArgList ) {
   return WholeArchiveActive;
 }
 
+/// Determine if driver is invoked to create a shared object library (-static)
 static bool isSharedLinkage(const ArgList ) {
-  bool FoundSharedFlag = false;
-  for (auto *Arg : Args.filtered(options::OPT_shared)) {
-if (Arg) {
-  FoundSharedFlag = true;
-}
-  }
+  return Args.hasArg(options::OPT_shared);
+}
 
-  return FoundSharedFlag;
+/// Determine if driver is invoked to create a static object library (-shared)
+static bool isStaticLinkage(const ArgList ) {
+  return Args.hasArg(options::OPT_static);
 }
 
 /// Add Fortran runtime libs for MSVC
@@ -1176,13 +1175,12 @@ static void addFortranRuntimeLibsMSVC(const ArgList 
,
 static void addFortranMain(const ToolChain , const ArgList ,
llvm::opt::ArgStringList ) {
   // 0. Shared-library linkage
-  // If we are attempting to link a shared library, we should not add
+  // If we are attempting to link a library, we should not add
   // -lFortran_main.a to the link line, as the `main` symbol is not
-  // required for a shared library and should also be provided by one
-  // of the translation units of the code that this shared library
+  // required for a library and should also be provided by one of
+  // the translation units of the code that this shared library
   // will be linked against eventually.
-  if (isSharedLinkage(Args)) {
-printf("MK: --> shared linkage, do not add -lFortranMain\n");
+  if (isSharedLinkage(Args) || isStaticLinkage(Args)) {
 return;
   }
 
diff --git a/flang/test/Driver/dynamic-linker.f90 
b/flang/test/Driver/dynamic-linker.f90
index df119c22a2ea51..af07e2483f93fa 100644
--- a/flang/test/Driver/dynamic-linker.f90
+++ b/flang/test/Driver/dynamic-linker.f90
@@ -3,18 +3,22 @@
 
 ! RUN: %flang -### --target=x86_64-linux-gnu -rpath /path/to/dir -shared \
 ! RUN: -static %s 2>&1 | FileCheck \
-! RUN: --check-prefixes=GNU-LINKER-OPTIONS %s
+! RUN: --check-prefixes=GNU-LINKER-OPTIONS \
+! RUN: --implicit-check-not=GNU-LINKER-OPTIONS-NOT %s
 ! RUN: %flang -### --target=x86_64-windows-msvc -rpath /path/to/dir -shared \
 ! RUN: -static %s 2>&1 | FileCheck \
-! RUN: --check-prefixes=MSVC-LINKER-OPTIONS %s
+! RUN: --check-prefixes=MSVC-LINKER-OPTIONS \
+! RUN: 

[flang] [clang] [flang][Driver] Let the linker fail on multiple definitions of main() (PR #73124)

[Michael Klemm via cfe-commits]

mjklemm wrote:

> I see. So Fortran and C interoperability of F2003/F2008 is not supported yet 
> in Flang? 

It's rather untested and I'm working hard to get it fixed, so that we have 
well-defined behavior that is similar to other Fortran compilers like ifx and 
gfortran.

> Those ~100ish regression test cases we have were passing before this PR 
> though. Unfortunately, those test cases are not made public available yet. I 
> think I can copy the source code of one test case here, but it needs to be 
> run manually. Please let me know if that is desired to help debug the reason 
> of the regression.

Please share as many of these reproducers as you can, so that I can debug the 
regression and fix it.

```
ld.lld: error: duplicate symbol: main
>>> defined at ./bind_c09i.c
>>>bind_c09i.o:(.The_Code)
>>> defined at Fortran_main.c
>>>Fortran_main.c.o:(.text.main+0x0) in archive ./libFortran_main.a
flang-new: error: linker command failed with exit code 1 (use -v to see 
invocation)
```

This error message is a strong indication of potentially two things:

- Both Fortran and C/C++ provide the `main` entry point (Fortran via 
`Fortran_main.a` and C/C++ via a `main` function).  Since this led to some 
weird behavior in the past, this situation now leads to an error message.
- On C/C++ provides the `main` function.  In this case, please pass 
`-fno-fortran-main` when using `flang-new` link command line.  This will remove 
the `main` symbol coming from `Fortran_main.a`, because it's not needed.

https://github.com/llvm/llvm-project/pull/73124
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[flang] [clang] [flang][driver] Remove Fortain_main static library from linking stages (PR #75816)

[Michael Klemm via cfe-commits]

mjklemm wrote:

> > Also, not sure what defines `_QQEnvironmentDefaults ` and what exactly 
> > makes it problematic?
> 
> The `main` entrypoint also calls `_QQEnvironmentDefaults` to treat `argc`, 
> `argv`, etc. So, when `main` is included in the shared object, so will be 
> those symbols are used symbols, which makes no sense.

I need to correct myself: _QQEnvironmentDefaults is not a function that is 
called, but rather an external file-scope variable that creates that symbol.  
The symbol used to initialize that is `_FortranAProgramStart`.  Plus, there's 
`_FortranAProgramEndStatement` that also used by `Fortran_main.a`.  So, lot's 
of symbols that should not be in a dynamic library for no reason. :-)

https://github.com/llvm/llvm-project/pull/75816
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[flang] [clang] [flang][driver] Remove Fortain_main static library from linking stages (PR #75816)

[Michael Klemm via cfe-commits]

mjklemm wrote:

> Thanks! Mostly looks good, but I have a question:
> 
> > This leads to the problem that _QQmain and _QQEnvironmentDefaults (as of 
> > the time of this PR) are symbols marked as used, while main is being 
> > defined.
> 
> Sorry for being pedantic, but not sure I follow. `FortranMain` defines 
> `main`, which calls `_QQmain`. However, the latter wouldn't be available in a 
> library, right?

Yes, that's correct.  The `main` symbol calls `_QQmain`, which happens to be 
the entry point for the Fortran program unit.  

> Also, not sure what defines `_QQEnvironmentDefaults ` and what exactly makes 
> it problematic?

The `main` etrypoint also calls `_QQEnvironmentDefaults` to treat `argc`, 
`argv`, etc.  So, when `main` is included in the shared object, so will be 
those symbols are used symbols, which makes no sense.


> Btw, would you mind adding a note to the driver docs?

Sure, I was planning to do this for the previous PR already but got distracted. 
 Can you point me to the right place to add this?  Thanks!



https://github.com/llvm/llvm-project/pull/75816
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[flang] [clang] [flang][driver] Remove Fortain_main static library from linking stages (PR #75816)

[Michael Klemm via cfe-commits]

https://github.com/mjklemm created 
https://github.com/llvm/llvm-project/pull/75816

At present, when building static or shared libraries, Flang adds 
`-lFortran_main.a` (or `/WHOLEARCHIVE:Fortran.*.lib` pon Windows) to the link 
line.  This leads to the problem that `_QQmain` and `_QQEnvironmentDefaults` 
(as of the time of this PR) are symbols marked as used, while `main` is being 
defined.  This should not happen and this PR fixes this by detecting if 
`-shared` or `-static` is used on the Flang command line and removing the 
static `Fortran_main` library.

>From 511f3a4537267284554bf6b33470a01d747b8a94 Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Sat, 16 Dec 2023 20:15:17 +0100
Subject: [PATCH 1/2] Remove -lFortran_main from the link line when -shared is
 present

---
 clang/lib/Driver/ToolChains/CommonArgs.cpp | 22 ++
 1 file changed, 22 insertions(+)

diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp 
b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 45901ee7157f77..5d525d3794ad1d 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -1133,6 +1133,17 @@ static bool isWholeArchivePresent(const ArgList ) {
   return WholeArchiveActive;
 }
 
+static bool isSharedLinkage(const ArgList ) {
+  bool FoundSharedFlag = false;
+  for (auto *Arg : Args.filtered(options::OPT_shared)) {
+if (Arg) {
+  FoundSharedFlag = true;
+}
+  }
+
+  return FoundSharedFlag;
+}
+
 /// Add Fortran runtime libs for MSVC
 static void addFortranRuntimeLibsMSVC(const ArgList ,
   llvm::opt::ArgStringList ) {
@@ -1164,6 +1175,17 @@ static void addFortranRuntimeLibsMSVC(const ArgList 
,
 // Add FortranMain runtime lib
 static void addFortranMain(const ToolChain , const ArgList ,
llvm::opt::ArgStringList ) {
+  // 0. Shared-library linkage
+  // If we are attempting to link a shared library, we should not add
+  // -lFortran_main.a to the link line, as the `main` symbol is not
+  // required for a shared library and should also be provided by one
+  // of the translation units of the code that this shared library
+  // will be linked against eventually.
+  if (isSharedLinkage(Args)) {
+printf("MK: --> shared linkage, do not add -lFortranMain\n");
+return;
+  }
+
   // 1. MSVC
   if (TC.getTriple().isKnownWindowsMSVCEnvironment()) {
 addFortranRuntimeLibsMSVC(Args, CmdArgs);

>From 930f2c447daa625d9e6019cd38d82b5750942f5d Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Mon, 18 Dec 2023 11:27:59 +0100
Subject: [PATCH 2/2] Update dynamic_linker.f90 test and clean up a bit

---
 clang/lib/Driver/ToolChains/CommonArgs.cpp | 22 ++
 flang/test/Driver/dynamic-linker.f90   |  8 ++--
 2 files changed, 16 insertions(+), 14 deletions(-)

diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp 
b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 5d525d3794ad1d..05ebd42829c95d 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -1133,15 +1133,14 @@ static bool isWholeArchivePresent(const ArgList ) {
   return WholeArchiveActive;
 }
 
+/// Determine if driver is invoked to create a shared object library (-static)
 static bool isSharedLinkage(const ArgList ) {
-  bool FoundSharedFlag = false;
-  for (auto *Arg : Args.filtered(options::OPT_shared)) {
-if (Arg) {
-  FoundSharedFlag = true;
-}
-  }
+  return Args.hasArg(options::OPT_shared);
+}
 
-  return FoundSharedFlag;
+/// Determine if driver is invoked to create a static object library (-shared)
+static bool isStaticLinkage(const ArgList ) {
+  return Args.hasArg(options::OPT_static);
 }
 
 /// Add Fortran runtime libs for MSVC
@@ -1176,13 +1175,12 @@ static void addFortranRuntimeLibsMSVC(const ArgList 
,
 static void addFortranMain(const ToolChain , const ArgList ,
llvm::opt::ArgStringList ) {
   // 0. Shared-library linkage
-  // If we are attempting to link a shared library, we should not add
+  // If we are attempting to link a library, we should not add
   // -lFortran_main.a to the link line, as the `main` symbol is not
-  // required for a shared library and should also be provided by one
-  // of the translation units of the code that this shared library
+  // required for a library and should also be provided by one of
+  // the translation units of the code that this shared library
   // will be linked against eventually.
-  if (isSharedLinkage(Args)) {
-printf("MK: --> shared linkage, do not add -lFortranMain\n");
+  if (isSharedLinkage(Args) || isStaticLinkage(Args)) {
 return;
   }
 
diff --git a/flang/test/Driver/dynamic-linker.f90 
b/flang/test/Driver/dynamic-linker.f90
index df119c22a2ea51..af07e2483f93fa 100644
--- a/flang/test/Driver/dynamic-linker.f90
+++ b/flang/test/Driver/dynamic-linker.f90
@@ -3,18 +3,22 @@
 
 ! RUN: %flang -### --target=x86_64-linux-gnu -rpath 

[clang] [flang][nfc] Refactor linker invocation logic (PR #75648)

[Michael Klemm via cfe-commits]

https://github.com/mjklemm approved this pull request.

Looks good to me.  Did touch testing with my reproducers and it worked as I 
would expect it.

https://github.com/llvm/llvm-project/pull/75648
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[clang] [flang] [flang][nfc] Refactor linker invocation logic (PR #75534)

[Michael Klemm via cfe-commits]

@@ -1116,73 +1116,87 @@ bool tools::addOpenMPRuntime(ArgStringList , 
const ToolChain ,
   return true;
 }
 
+/// Determines if --whole-archive is active in the list of arguments.
+static bool isWholeArchivePresent(const ArgList ) {
+  bool WholeArchiveActive = false;
+  for (auto *Arg : Args.filtered(options::OPT_Wl_COMMA)) {
+if (Arg) {

mjklemm wrote:

Thanks!

https://github.com/llvm/llvm-project/pull/75534
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[clang] [flang] [flang][nfc] Refactor linker invocation logic (PR #75534)

[Michael Klemm via cfe-commits]

@@ -1116,73 +1116,87 @@ bool tools::addOpenMPRuntime(ArgStringList , 
const ToolChain ,
   return true;
 }
 
+/// Determines if --whole-archive is active in the list of arguments.
+static bool isWholeArchivePresent(const ArgList ) {
+  bool WholeArchiveActive = false;
+  for (auto *Arg : Args.filtered(options::OPT_Wl_COMMA)) {
+if (Arg) {

mjklemm wrote:

Nit (and maybe more a question): The style guide does not use {} when only one 
statement is nested. Is that true? (Frankly, I like the extra {} better, as it 
makes adding code easier). 

https://github.com/llvm/llvm-project/pull/75534
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[clang] [flang] [flang][nfc] Refactor linker invocation logic (PR #75534)

[Michael Klemm via cfe-commits]

https://github.com/mjklemm approved this pull request.

LGTM!

Thanks for the refactoring.  This makes the code much easier to digest!

https://github.com/llvm/llvm-project/pull/75534
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[flang] [clang] [flang][nfc] Refactor linker invocation logic (PR #75534)

[Michael Klemm via cfe-commits]

https://github.com/mjklemm edited 
https://github.com/llvm/llvm-project/pull/75534
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[clang] [flang][driver] Don't use -whole-archive on Darwin (PR #75393)

[Michael Klemm via cfe-commits]

mjklemm wrote:

Let's get this in. I agree with the assessment by @banach-space. The PR looks 
good to me. 

https://github.com/llvm/llvm-project/pull/75393
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[clang] [flang][driver] Don't use -whole-archive on Darwin (PR #75393)

[Michael Klemm via cfe-commits]

mjklemm wrote:

> > LGTM. Worked fine on my machine.
> 
> > 
> 
> > NOTE: tested by replacing `CommonArgs.cpp` in main, to avoid conflicts.
> 
> 
> 
> Thanks for checking and apologies for the merge conflict - I thought that I 
> was up to date :( I've just rebased and force-pushed. 
> 
> 
> 
> I will be landing this today if there are no further comments  

This patch seems to hide the original problem of the compiler not erroring out 
when multiple definitions of main happen.  T think we should rather inject the 
proper linker equivalent of --whole-archive on Darwin, too.

I'd be OK to land this patch for now, if we agree to have a follow up PR to 
(re-)instantiate the error handling also for Darwin.

https://github.com/llvm/llvm-project/pull/75393
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[clang] [flang] [flang][Driver] Let the linker fail on multiple definitions of main() (PR #73124)

[Michael Klemm via cfe-commits]

mjklemm wrote:

> We are also seeing the same issue when linking on Mac regarding the ld: 
> unknown options: --whole-archive

Is there an equivalent option for the MacOS linker?

https://github.com/llvm/llvm-project/pull/73124
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[flang] [clang] [flang][Driver] Let the linker fail on multiple definitions of main() (PR #73124)

[Michael Klemm via cfe-commits]

mjklemm wrote:

@tblah @rj-jesus https://github.com/llvm/llvm-project/pull/74139 has landed.  
Can you please see if `-fno-fortran-main` helps to resolve your bugs?  I will 
write up a blog article about this and publish it.  Maybe it would be worth 
documenting this as a question on StackOverflow, too?

https://github.com/llvm/llvm-project/pull/73124
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[flang] [clang] [flang][driver] Add -fno-fortran-main (link time) option to remove Fortran_main from link line (PR #74139)

[Michael Klemm via cfe-commits]

https://github.com/mjklemm closed 
https://github.com/llvm/llvm-project/pull/74139
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[flang] [clang] [flang][driver] Add -fno-fortran-main (link time) option to remove Fortran_main from link line (PR #74139)

[Michael Klemm via cfe-commits]

https://github.com/mjklemm updated 
https://github.com/llvm/llvm-project/pull/74139

>From e0784bd3a6103fe6852ecc67fb01a4a8da1cf59a Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Fri, 1 Dec 2023 21:41:44 +0100
Subject: [PATCH 1/9] Add -fno-fortran-main driver option

---
 clang/include/clang/Driver/Options.td | 4 
 1 file changed, 4 insertions(+)

diff --git a/clang/include/clang/Driver/Options.td 
b/clang/include/clang/Driver/Options.td
index b959fd20fe413..057f1f4b90955 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -6354,6 +6354,10 @@ def J : JoinedOrSeparate<["-"], "J">,
   Group,
   Alias;
 
+def no_fortran_main : Flag<["-"], "fno-fortran-main">,
+  Visibility<[FlangOption]>, Group,
+  HelpText<"Don't link in Fortran main">;
+
 
//===--===//
 // FC1 Options
 
//===--===//

>From 5c2f898be0d16fdecd44fbcf94cb0513e9a75bb2 Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Fri, 1 Dec 2023 21:42:09 +0100
Subject: [PATCH 2/9] Skip linking Fortran_main.a if -fno-fortran-main is
 present

---
 clang/lib/Driver/ToolChains/CommonArgs.cpp | 46 --
 1 file changed, 25 insertions(+), 21 deletions(-)

diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp 
b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 51b336216c565..82ed3e53d9960 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -1116,33 +1116,37 @@ bool tools::addOpenMPRuntime(ArgStringList , 
const ToolChain ,
   return true;
 }
 
+// TODO: add -fno-fortran-main option and check it in this function.
 void tools::addFortranRuntimeLibs(const ToolChain , const ArgList ,
   llvm::opt::ArgStringList ) {
   // These are handled earlier on Windows by telling the frontend driver to add
   // the correct libraries to link against as dependents in the object file.
   if (!TC.getTriple().isKnownWindowsMSVCEnvironment()) {
-// The --whole-archive option needs to be part of the link line to
-// make sure that the main() function from Fortran_main.a is pulled
-// in by the linker.  Determine if --whole-archive is active when
-// flang will try to link Fortran_main.a.  If it is, don't add the
-// --whole-archive flag to the link line.  If it's not, add a proper
-// --whole-archive/--no-whole-archive bracket to the link line.
-bool WholeArchiveActive = false;
-for (auto *Arg : Args.filtered(options::OPT_Wl_COMMA))
-  if (Arg)
-for (StringRef ArgValue : Arg->getValues()) {
-  if (ArgValue == "--whole-archive")
-WholeArchiveActive = true;
-  if (ArgValue == "--no-whole-archive")
-WholeArchiveActive = false;
-}
-
-if (!WholeArchiveActive)
-  CmdArgs.push_back("--whole-archive");
-CmdArgs.push_back("-lFortran_main");
-if (!WholeArchiveActive)
-  CmdArgs.push_back("--no-whole-archive");
+// if -fno-fortran-main has been passed, skip linking Fortran_main.a
+bool DontLinkFortranMain = Args.getLastArg(options::OPT_no_fortran_main) 
!= nullptr;
+if (!DontLinkFortranMain) {
+  // The --whole-archive option needs to be part of the link line to
+  // make sure that the main() function from Fortran_main.a is pulled
+  // in by the linker.  Determine if --whole-archive is active when
+  // flang will try to link Fortran_main.a.  If it is, don't add the
+  // --whole-archive flag to the link line.  If it's not, add a proper
+  // --whole-archive/--no-whole-archive bracket to the link line.
+  bool WholeArchiveActive = false;
+  for (auto *Arg : Args.filtered(options::OPT_Wl_COMMA))
+if (Arg)
+  for (StringRef ArgValue : Arg->getValues()) {
+if (ArgValue == "--whole-archive")
+  WholeArchiveActive = true;
+if (ArgValue == "--no-whole-archive")
+  WholeArchiveActive = false;
+  }
 
+  if (!WholeArchiveActive)
+CmdArgs.push_back("--whole-archive");
+  CmdArgs.push_back("-lFortran_main");
+  if (!WholeArchiveActive)
+CmdArgs.push_back("--no-whole-archive");
+}
 // Perform regular linkage of the remaining runtime libraries.
 CmdArgs.push_back("-lFortranRuntime");
 CmdArgs.push_back("-lFortranDecimal");

>From a87bdd40e2f4e707a47a185b49a93ae84c809bda Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Fri, 1 Dec 2023 15:10:29 -0600
Subject: [PATCH 3/9] Cleanup and simplify the code a bit

---
 clang/lib/Driver/ToolChains/CommonArgs.cpp | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp 
b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 82ed3e53d9960..93877b75beaf7 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ 

[flang] [clang] [flang][driver] Add -fno-fortran-main (link time) option to remove Fortran_main from link line (PR #74139)

[Michael Klemm via cfe-commits]

@@ -6345,6 +6345,10 @@ def J : JoinedOrSeparate<["-"], "J">,
   Group,
   Alias;
 
+def no_fortran_main : Flag<["-"], "fno-fortran-main">,
+  Visibility<[FlangOption]>, Group,
+  HelpText<"Don't link in Fortran main">;

mjklemm wrote:

Done, with a slightly different wording

https://github.com/llvm/llvm-project/pull/74139
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[clang] [flang] [flang][driver] Add -fno-fortran-main (link time) option to remove Fortran_main from link line (PR #74139)

[Michael Klemm via cfe-commits]

https://github.com/mjklemm updated 
https://github.com/llvm/llvm-project/pull/74139

>From 2e41335a7de3d2efa88eacee659172a3b9525e45 Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Fri, 1 Dec 2023 21:41:44 +0100
Subject: [PATCH 1/9] Add -fno-fortran-main driver option

---
 clang/include/clang/Driver/Options.td | 4 
 1 file changed, 4 insertions(+)

diff --git a/clang/include/clang/Driver/Options.td 
b/clang/include/clang/Driver/Options.td
index 19d04e82aed4d6..aa26344f67b313 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -6345,6 +6345,10 @@ def J : JoinedOrSeparate<["-"], "J">,
   Group,
   Alias;
 
+def no_fortran_main : Flag<["-"], "fno-fortran-main">,
+  Visibility<[FlangOption]>, Group,
+  HelpText<"Don't link in Fortran main">;
+
 
//===--===//
 // FC1 Options
 
//===--===//

>From 44b684ae43a6da37bb56c5b699628c6807257ad9 Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Fri, 1 Dec 2023 21:42:09 +0100
Subject: [PATCH 2/9] Skip linking Fortran_main.a if -fno-fortran-main is
 present

---
 clang/lib/Driver/ToolChains/CommonArgs.cpp | 46 --
 1 file changed, 25 insertions(+), 21 deletions(-)

diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp 
b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 0ae8e2dce32e94..2899f07cb7490c 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -1116,33 +1116,37 @@ bool tools::addOpenMPRuntime(ArgStringList , 
const ToolChain ,
   return true;
 }
 
+// TODO: add -fno-fortran-main option and check it in this function.
 void tools::addFortranRuntimeLibs(const ToolChain , const ArgList ,
   llvm::opt::ArgStringList ) {
   // These are handled earlier on Windows by telling the frontend driver to add
   // the correct libraries to link against as dependents in the object file.
   if (!TC.getTriple().isKnownWindowsMSVCEnvironment()) {
-// The --whole-archive option needs to be part of the link line to
-// make sure that the main() function from Fortran_main.a is pulled
-// in by the linker.  Determine if --whole-archive is active when
-// flang will try to link Fortran_main.a.  If it is, don't add the
-// --whole-archive flag to the link line.  If it's not, add a proper
-// --whole-archive/--no-whole-archive bracket to the link line.
-bool WholeArchiveActive = false;
-for (auto *Arg : Args.filtered(options::OPT_Wl_COMMA))
-  if (Arg)
-for (StringRef ArgValue : Arg->getValues()) {
-  if (ArgValue == "--whole-archive")
-WholeArchiveActive = true;
-  if (ArgValue == "--no-whole-archive")
-WholeArchiveActive = false;
-}
-
-if (!WholeArchiveActive)
-  CmdArgs.push_back("--whole-archive");
-CmdArgs.push_back("-lFortran_main");
-if (!WholeArchiveActive)
-  CmdArgs.push_back("--no-whole-archive");
+// if -fno-fortran-main has been passed, skip linking Fortran_main.a
+bool DontLinkFortranMain = Args.getLastArg(options::OPT_no_fortran_main) 
!= nullptr;
+if (!DontLinkFortranMain) {
+  // The --whole-archive option needs to be part of the link line to
+  // make sure that the main() function from Fortran_main.a is pulled
+  // in by the linker.  Determine if --whole-archive is active when
+  // flang will try to link Fortran_main.a.  If it is, don't add the
+  // --whole-archive flag to the link line.  If it's not, add a proper
+  // --whole-archive/--no-whole-archive bracket to the link line.
+  bool WholeArchiveActive = false;
+  for (auto *Arg : Args.filtered(options::OPT_Wl_COMMA))
+if (Arg)
+  for (StringRef ArgValue : Arg->getValues()) {
+if (ArgValue == "--whole-archive")
+  WholeArchiveActive = true;
+if (ArgValue == "--no-whole-archive")
+  WholeArchiveActive = false;
+  }
 
+  if (!WholeArchiveActive)
+CmdArgs.push_back("--whole-archive");
+  CmdArgs.push_back("-lFortran_main");
+  if (!WholeArchiveActive)
+CmdArgs.push_back("--no-whole-archive");
+}
 // Perform regular linkage of the remaining runtime libraries.
 CmdArgs.push_back("-lFortranRuntime");
 CmdArgs.push_back("-lFortranDecimal");

>From e1a472fa914ea9405be6589e89fbe8201448600f Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Fri, 1 Dec 2023 15:10:29 -0600
Subject: [PATCH 3/9] Cleanup and simplify the code a bit

---
 clang/lib/Driver/ToolChains/CommonArgs.cpp | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp 
b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 2899f07cb7490c..f0e3df2a63ae98 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ 

[flang] [clang] [flang][driver] Add -fno-fortran-main (link time) option to remove Fortran_main from link line (PR #74139)

[Michael Klemm via cfe-commits]

https://github.com/mjklemm edited 
https://github.com/llvm/llvm-project/pull/74139
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[clang] [flang] [flang][driver] Rename `flang-new` as `flang` (PR #74377)

[Michael Klemm via cfe-commits]

mjklemm wrote:

I have a Windows test machine.  How can I help?

https://github.com/llvm/llvm-project/pull/74377
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[flang] [clang] [flang][driver] Add -fno-fortran-main (link time) option to remove Fortran_main from link line (PR #74139)

[Michael Klemm via cfe-commits]

https://github.com/mjklemm edited 
https://github.com/llvm/llvm-project/pull/74139
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[clang] [flang] [flang][driver] Add -fno-fortran-main (link time) option to remove Fortran_main from link line (PR #74139)

[Michael Klemm via cfe-commits]

mjklemm wrote:

> I know that it's extra work, but it's also super useful bit of documentation. 
> And I would only rarely try to track the history beyond commit messages 
> (there's just too much otherwise).

I can absolutely do that.  I'll craft some wording for the rationale behind 
that change and add it to the PR.

https://github.com/llvm/llvm-project/pull/74139
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[clang] [flang] [flang][driver] Add -fno-fortran-main (link time) option to remove Fortran_main from link line (PR #74139)

[Michael Klemm via cfe-commits]

@@ -6345,6 +6345,10 @@ def J : JoinedOrSeparate<["-"], "J">,
   Group,
   Alias;
 
+def no_fortran_main : Flag<["-"], "fno-fortran-main">,
+  Visibility<[FlangOption]>, Group,
+  HelpText<"Don't link in Fortran main">;
+

mjklemm wrote:

@banach-space 

```
let Visibility = [FlangOption] in {
def no_fortran_main : Flag<["-"], "fno-fortran-main">,
  Visibility<[FlangOption]>, Group,
  HelpText<"Don't link in Fortran main">;
} // let Visibility = [ FlangOption ]
```

Was that the suggested edit?  I guess  `-J` should not be be modified as part 
of the edit, right?

https://github.com/llvm/llvm-project/pull/74139
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[clang] [flang] [flang][driver] Add -fno-fortran-main (link time) option to remove Fortran_main from link line (PR #74139)

[Michael Klemm via cfe-commits]

https://github.com/mjklemm updated 
https://github.com/llvm/llvm-project/pull/74139

>From 2e41335a7de3d2efa88eacee659172a3b9525e45 Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Fri, 1 Dec 2023 21:41:44 +0100
Subject: [PATCH 1/8] Add -fno-fortran-main driver option

---
 clang/include/clang/Driver/Options.td | 4 
 1 file changed, 4 insertions(+)

diff --git a/clang/include/clang/Driver/Options.td 
b/clang/include/clang/Driver/Options.td
index 19d04e82aed4d..aa26344f67b31 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -6345,6 +6345,10 @@ def J : JoinedOrSeparate<["-"], "J">,
   Group,
   Alias;
 
+def no_fortran_main : Flag<["-"], "fno-fortran-main">,
+  Visibility<[FlangOption]>, Group,
+  HelpText<"Don't link in Fortran main">;
+
 
//===--===//
 // FC1 Options
 
//===--===//

>From 44b684ae43a6da37bb56c5b699628c6807257ad9 Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Fri, 1 Dec 2023 21:42:09 +0100
Subject: [PATCH 2/8] Skip linking Fortran_main.a if -fno-fortran-main is
 present

---
 clang/lib/Driver/ToolChains/CommonArgs.cpp | 46 --
 1 file changed, 25 insertions(+), 21 deletions(-)

diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp 
b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 0ae8e2dce32e9..2899f07cb7490 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -1116,33 +1116,37 @@ bool tools::addOpenMPRuntime(ArgStringList , 
const ToolChain ,
   return true;
 }
 
+// TODO: add -fno-fortran-main option and check it in this function.
 void tools::addFortranRuntimeLibs(const ToolChain , const ArgList ,
   llvm::opt::ArgStringList ) {
   // These are handled earlier on Windows by telling the frontend driver to add
   // the correct libraries to link against as dependents in the object file.
   if (!TC.getTriple().isKnownWindowsMSVCEnvironment()) {
-// The --whole-archive option needs to be part of the link line to
-// make sure that the main() function from Fortran_main.a is pulled
-// in by the linker.  Determine if --whole-archive is active when
-// flang will try to link Fortran_main.a.  If it is, don't add the
-// --whole-archive flag to the link line.  If it's not, add a proper
-// --whole-archive/--no-whole-archive bracket to the link line.
-bool WholeArchiveActive = false;
-for (auto *Arg : Args.filtered(options::OPT_Wl_COMMA))
-  if (Arg)
-for (StringRef ArgValue : Arg->getValues()) {
-  if (ArgValue == "--whole-archive")
-WholeArchiveActive = true;
-  if (ArgValue == "--no-whole-archive")
-WholeArchiveActive = false;
-}
-
-if (!WholeArchiveActive)
-  CmdArgs.push_back("--whole-archive");
-CmdArgs.push_back("-lFortran_main");
-if (!WholeArchiveActive)
-  CmdArgs.push_back("--no-whole-archive");
+// if -fno-fortran-main has been passed, skip linking Fortran_main.a
+bool DontLinkFortranMain = Args.getLastArg(options::OPT_no_fortran_main) 
!= nullptr;
+if (!DontLinkFortranMain) {
+  // The --whole-archive option needs to be part of the link line to
+  // make sure that the main() function from Fortran_main.a is pulled
+  // in by the linker.  Determine if --whole-archive is active when
+  // flang will try to link Fortran_main.a.  If it is, don't add the
+  // --whole-archive flag to the link line.  If it's not, add a proper
+  // --whole-archive/--no-whole-archive bracket to the link line.
+  bool WholeArchiveActive = false;
+  for (auto *Arg : Args.filtered(options::OPT_Wl_COMMA))
+if (Arg)
+  for (StringRef ArgValue : Arg->getValues()) {
+if (ArgValue == "--whole-archive")
+  WholeArchiveActive = true;
+if (ArgValue == "--no-whole-archive")
+  WholeArchiveActive = false;
+  }
 
+  if (!WholeArchiveActive)
+CmdArgs.push_back("--whole-archive");
+  CmdArgs.push_back("-lFortran_main");
+  if (!WholeArchiveActive)
+CmdArgs.push_back("--no-whole-archive");
+}
 // Perform regular linkage of the remaining runtime libraries.
 CmdArgs.push_back("-lFortranRuntime");
 CmdArgs.push_back("-lFortranDecimal");

>From e1a472fa914ea9405be6589e89fbe8201448600f Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Fri, 1 Dec 2023 15:10:29 -0600
Subject: [PATCH 3/8] Cleanup and simplify the code a bit

---
 clang/lib/Driver/ToolChains/CommonArgs.cpp | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp 
b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 2899f07cb7490..f0e3df2a63ae9 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ 

[clang] [flang] [flang][driver] Add -fno-fortran-main (link time) option to remove Fortran_main from link line (PR #74139)

[Michael Klemm via cfe-commits]

https://github.com/mjklemm updated 
https://github.com/llvm/llvm-project/pull/74139

>From 2e41335a7de3d2efa88eacee659172a3b9525e45 Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Fri, 1 Dec 2023 21:41:44 +0100
Subject: [PATCH 1/7] Add -fno-fortran-main driver option

---
 clang/include/clang/Driver/Options.td | 4 
 1 file changed, 4 insertions(+)

diff --git a/clang/include/clang/Driver/Options.td 
b/clang/include/clang/Driver/Options.td
index 19d04e82aed4d..aa26344f67b31 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -6345,6 +6345,10 @@ def J : JoinedOrSeparate<["-"], "J">,
   Group,
   Alias;
 
+def no_fortran_main : Flag<["-"], "fno-fortran-main">,
+  Visibility<[FlangOption]>, Group,
+  HelpText<"Don't link in Fortran main">;
+
 
//===--===//
 // FC1 Options
 
//===--===//

>From 44b684ae43a6da37bb56c5b699628c6807257ad9 Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Fri, 1 Dec 2023 21:42:09 +0100
Subject: [PATCH 2/7] Skip linking Fortran_main.a if -fno-fortran-main is
 present

---
 clang/lib/Driver/ToolChains/CommonArgs.cpp | 46 --
 1 file changed, 25 insertions(+), 21 deletions(-)

diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp 
b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 0ae8e2dce32e9..2899f07cb7490 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -1116,33 +1116,37 @@ bool tools::addOpenMPRuntime(ArgStringList , 
const ToolChain ,
   return true;
 }
 
+// TODO: add -fno-fortran-main option and check it in this function.
 void tools::addFortranRuntimeLibs(const ToolChain , const ArgList ,
   llvm::opt::ArgStringList ) {
   // These are handled earlier on Windows by telling the frontend driver to add
   // the correct libraries to link against as dependents in the object file.
   if (!TC.getTriple().isKnownWindowsMSVCEnvironment()) {
-// The --whole-archive option needs to be part of the link line to
-// make sure that the main() function from Fortran_main.a is pulled
-// in by the linker.  Determine if --whole-archive is active when
-// flang will try to link Fortran_main.a.  If it is, don't add the
-// --whole-archive flag to the link line.  If it's not, add a proper
-// --whole-archive/--no-whole-archive bracket to the link line.
-bool WholeArchiveActive = false;
-for (auto *Arg : Args.filtered(options::OPT_Wl_COMMA))
-  if (Arg)
-for (StringRef ArgValue : Arg->getValues()) {
-  if (ArgValue == "--whole-archive")
-WholeArchiveActive = true;
-  if (ArgValue == "--no-whole-archive")
-WholeArchiveActive = false;
-}
-
-if (!WholeArchiveActive)
-  CmdArgs.push_back("--whole-archive");
-CmdArgs.push_back("-lFortran_main");
-if (!WholeArchiveActive)
-  CmdArgs.push_back("--no-whole-archive");
+// if -fno-fortran-main has been passed, skip linking Fortran_main.a
+bool DontLinkFortranMain = Args.getLastArg(options::OPT_no_fortran_main) 
!= nullptr;
+if (!DontLinkFortranMain) {
+  // The --whole-archive option needs to be part of the link line to
+  // make sure that the main() function from Fortran_main.a is pulled
+  // in by the linker.  Determine if --whole-archive is active when
+  // flang will try to link Fortran_main.a.  If it is, don't add the
+  // --whole-archive flag to the link line.  If it's not, add a proper
+  // --whole-archive/--no-whole-archive bracket to the link line.
+  bool WholeArchiveActive = false;
+  for (auto *Arg : Args.filtered(options::OPT_Wl_COMMA))
+if (Arg)
+  for (StringRef ArgValue : Arg->getValues()) {
+if (ArgValue == "--whole-archive")
+  WholeArchiveActive = true;
+if (ArgValue == "--no-whole-archive")
+  WholeArchiveActive = false;
+  }
 
+  if (!WholeArchiveActive)
+CmdArgs.push_back("--whole-archive");
+  CmdArgs.push_back("-lFortran_main");
+  if (!WholeArchiveActive)
+CmdArgs.push_back("--no-whole-archive");
+}
 // Perform regular linkage of the remaining runtime libraries.
 CmdArgs.push_back("-lFortranRuntime");
 CmdArgs.push_back("-lFortranDecimal");

>From e1a472fa914ea9405be6589e89fbe8201448600f Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Fri, 1 Dec 2023 15:10:29 -0600
Subject: [PATCH 3/7] Cleanup and simplify the code a bit

---
 clang/lib/Driver/ToolChains/CommonArgs.cpp | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp 
b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 2899f07cb7490..f0e3df2a63ae9 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ 

[clang] [flang] [flang][Driver] Let the linker fail on multiple definitions of main() (PR #73124)

[Michael Klemm via cfe-commits]

mjklemm wrote:

Thanks for the reproducer.

> The error shows up when linking a C program with a Fortran shared library, so 
> maybe you weren't enabling building shared libraries?

I was building OpenBLAS using the "old" Makefile-based build.  There the issue 
indeed does not happen.  When I switched to your CMake configuration line, I 
was able to reproduce the problem.

The solution is to add `-fno-fortran-main` to the linker options via 
`CMAKE_SHARED_LINKER_FLAGS`.  This will need PR 
https://github.com/llvm/llvm-project/pull/74139 land first.  But this option 
will be a good way to control if the flang compiler should attempt linking in 
the `main` stub from its library.

It seems like `flang-new` when being used as a linker with `-shared` included 
Fortran_main in the shared library.  This seems wrong to me.  The option 
`-fno-fortran-main` avoids this.  I'm pondering if `-shared` is buggy here.  It 
will require a bit more digging on my end to figure that out.


https://github.com/llvm/llvm-project/pull/73124
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[flang] [clang] [flang][Driver] Let the linker fail on multiple definitions of main() (PR #73124)

[Michael Klemm via cfe-commits]

mjklemm wrote:

> Chipping into the discussion, since this patch I can also no longer build 
> OpenBLAS or PETSc. OpenBLAS for example fails with
> 
> ```
> $ clang -v -O3 -mcpu=native  -DHAVE_C11 -Wall -DF_INTERFACE_GFORT -fPIC 
> -DSMP_SERVER -DNO_WARMUP -DMAX_CPU_NUMBER=72 -DMAX_PARALLEL_NUMBER=1 
> -DMAX_STACK_ALLOC=2048 -DNO_AFFINITY -DVERSION="\"0.3.25\"" -DBUILD_SINGLE 
> -DBUILD_DOUBLE -DBUILD_COMPLEX -DBUILD_COMPLEX16  
> utest/CMakeFiles/openblas_utest.dir/utest_main.c.o 
> utest/CMakeFiles/openblas_utest.dir/test_min.c.o 
> utest/CMakeFiles/openblas_utest.dir/test_amax.c.o 
> utest/CMakeFiles/openblas_utest.dir/test_ismin.c.o 
> utest/CMakeFiles/openblas_utest.dir/test_rotmg.c.o 
> utest/CMakeFiles/openblas_utest.dir/test_rot.c.o 
> utest/CMakeFiles/openblas_utest.dir/test_axpy.c.o 
> utest/CMakeFiles/openblas_utest.dir/test_dsdot.c.o 
> utest/CMakeFiles/openblas_utest.dir/test_dnrm2.c.o 
> utest/CMakeFiles/openblas_utest.dir/test_swap.c.o 
> utest/CMakeFiles/openblas_utest.dir/test_dotu.c.o 
> utest/CMakeFiles/openblas_utest.dir/test_potrs.c.o 
> utest/CMakeFiles/openblas_utest.dir/test_kernel_regress.c.o -o 
> utest/openblas_utest  -Wl,-rpath,/.../openblas/build/lib  
> lib/libopenblas.so.0.3  -lm
> clang version 18.0.0 (g...@github.com:llvm/llvm-project.git 
> 17feb330aab39c6c0c21ee9b02efb484dfb2261e)
> Target: aarch64-unknown-linux-gnu
> Thread model: posix
> InstalledDir: /.../llvm/trunk/bin
> Found candidate GCC installation: /usr/lib/gcc/aarch64-linux-gnu/11
> Found candidate GCC installation: /usr/lib/gcc/aarch64-linux-gnu/12
> Selected GCC installation: /usr/lib/gcc/aarch64-linux-gnu/12
> Candidate multilib: .;@m64
> Selected multilib: .;@m64
> Found CUDA installation: /usr/local/cuda, version 
>  "/usr/bin/ld" -EL -z relro --hash-style=gnu --eh-frame-hdr -m aarch64linux 
> -pie -dynamic-linker /lib/ld-linux-aarch64.so.1 -o utest/openblas_utest 
> /lib/aarch64-linux-gnu/Scrt1.o /lib/aarch64-linux-gnu/crti.o 
> /usr/lib/gcc/aarch64-linux-gnu/12/crtbeginS.o 
> -L/.../llvm/trunk/lib/clang/18/lib/aarch64-unknown-linux-gnu 
> -L/usr/lib/gcc/aarch64-linux-gnu/12 -L/lib/aarch64-linux-gnu 
> -L/usr/lib/aarch64-linux-gnu -L/lib -L/usr/lib -L/.../llvm/trunk/lib 
> utest/CMakeFiles/openblas_utest.dir/utest_main.c.o 
> utest/CMakeFiles/openblas_utest.dir/test_min.c.o 
> utest/CMakeFiles/openblas_utest.dir/test_amax.c.o 
> utest/CMakeFiles/openblas_utest.dir/test_ismin.c.o 
> utest/CMakeFiles/openblas_utest.dir/test_rotmg.c.o 
> utest/CMakeFiles/openblas_utest.dir/test_rot.c.o 
> utest/CMakeFiles/openblas_utest.dir/test_axpy.c.o 
> utest/CMakeFiles/openblas_utest.dir/test_dsdot.c.o 
> utest/CMakeFiles/openblas_utest.dir/test_dnrm2.c.o 
> utest/CMakeFiles/openblas_utest.dir/test_swap.c.o 
> utest/CMakeFiles/openblas_utest.dir/test_dotu.c.o 
> utest/CMakeFiles/openblas_utest.dir/test_potrs.c.o 
> utest/CMakeFiles/openblas_utest.dir/test_kernel_regress.c.o -rpath 
> /.../openblas/build/lib lib/libopenblas.so.0.3 -lm -lgcc --as-needed -lgcc_s 
> --no-as-needed -lc -lgcc --as-needed -lgcc_s --no-as-needed 
> /usr/lib/gcc/aarch64-linux-gnu/12/crtendS.o /lib/aarch64-linux-gnu/crtn.o
> /usr/bin/ld: lib/libopenblas.so.0.3: undefined reference to 
> `_QQEnvironmentDefaults'
> /usr/bin/ld: lib/libopenblas.so.0.3: undefined reference to `_QQmain'
> ```

Thanks for the report!  Can you please tell me how OpenBLAS was built?  I'm 
trying to replicate this, but I do not see a reference to `_QQmain` or the 
likes in the OpenBLAS library that I build on x86.

https://github.com/llvm/llvm-project/pull/73124
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[flang] [clang] [flang][driver] Add -fno-fortran-main (link time) option to remove Fortran_main from link line (PR #74139)

[Michael Klemm via cfe-commits]

mjklemm wrote:

@DavidTruby If you are OK with the way I handled MSVC, please approve and I 
will merge the PR (or change it if you want some changes to be made).

https://github.com/llvm/llvm-project/pull/74139
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[clang] [flang] [flang][driver] Add -fno-fortran-main (link time) option to remove Fortran_main from link line (PR #74139)

[Michael Klemm via cfe-commits]

https://github.com/mjklemm updated 
https://github.com/llvm/llvm-project/pull/74139

>From 2e41335a7de3d2efa88eacee659172a3b9525e45 Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Fri, 1 Dec 2023 21:41:44 +0100
Subject: [PATCH 1/6] Add -fno-fortran-main driver option

---
 clang/include/clang/Driver/Options.td | 4 
 1 file changed, 4 insertions(+)

diff --git a/clang/include/clang/Driver/Options.td 
b/clang/include/clang/Driver/Options.td
index 19d04e82aed4d..aa26344f67b31 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -6345,6 +6345,10 @@ def J : JoinedOrSeparate<["-"], "J">,
   Group,
   Alias;
 
+def no_fortran_main : Flag<["-"], "fno-fortran-main">,
+  Visibility<[FlangOption]>, Group,
+  HelpText<"Don't link in Fortran main">;
+
 
//===--===//
 // FC1 Options
 
//===--===//

>From 44b684ae43a6da37bb56c5b699628c6807257ad9 Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Fri, 1 Dec 2023 21:42:09 +0100
Subject: [PATCH 2/6] Skip linking Fortran_main.a if -fno-fortran-main is
 present

---
 clang/lib/Driver/ToolChains/CommonArgs.cpp | 46 --
 1 file changed, 25 insertions(+), 21 deletions(-)

diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp 
b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 0ae8e2dce32e9..2899f07cb7490 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -1116,33 +1116,37 @@ bool tools::addOpenMPRuntime(ArgStringList , 
const ToolChain ,
   return true;
 }
 
+// TODO: add -fno-fortran-main option and check it in this function.
 void tools::addFortranRuntimeLibs(const ToolChain , const ArgList ,
   llvm::opt::ArgStringList ) {
   // These are handled earlier on Windows by telling the frontend driver to add
   // the correct libraries to link against as dependents in the object file.
   if (!TC.getTriple().isKnownWindowsMSVCEnvironment()) {
-// The --whole-archive option needs to be part of the link line to
-// make sure that the main() function from Fortran_main.a is pulled
-// in by the linker.  Determine if --whole-archive is active when
-// flang will try to link Fortran_main.a.  If it is, don't add the
-// --whole-archive flag to the link line.  If it's not, add a proper
-// --whole-archive/--no-whole-archive bracket to the link line.
-bool WholeArchiveActive = false;
-for (auto *Arg : Args.filtered(options::OPT_Wl_COMMA))
-  if (Arg)
-for (StringRef ArgValue : Arg->getValues()) {
-  if (ArgValue == "--whole-archive")
-WholeArchiveActive = true;
-  if (ArgValue == "--no-whole-archive")
-WholeArchiveActive = false;
-}
-
-if (!WholeArchiveActive)
-  CmdArgs.push_back("--whole-archive");
-CmdArgs.push_back("-lFortran_main");
-if (!WholeArchiveActive)
-  CmdArgs.push_back("--no-whole-archive");
+// if -fno-fortran-main has been passed, skip linking Fortran_main.a
+bool DontLinkFortranMain = Args.getLastArg(options::OPT_no_fortran_main) 
!= nullptr;
+if (!DontLinkFortranMain) {
+  // The --whole-archive option needs to be part of the link line to
+  // make sure that the main() function from Fortran_main.a is pulled
+  // in by the linker.  Determine if --whole-archive is active when
+  // flang will try to link Fortran_main.a.  If it is, don't add the
+  // --whole-archive flag to the link line.  If it's not, add a proper
+  // --whole-archive/--no-whole-archive bracket to the link line.
+  bool WholeArchiveActive = false;
+  for (auto *Arg : Args.filtered(options::OPT_Wl_COMMA))
+if (Arg)
+  for (StringRef ArgValue : Arg->getValues()) {
+if (ArgValue == "--whole-archive")
+  WholeArchiveActive = true;
+if (ArgValue == "--no-whole-archive")
+  WholeArchiveActive = false;
+  }
 
+  if (!WholeArchiveActive)
+CmdArgs.push_back("--whole-archive");
+  CmdArgs.push_back("-lFortran_main");
+  if (!WholeArchiveActive)
+CmdArgs.push_back("--no-whole-archive");
+}
 // Perform regular linkage of the remaining runtime libraries.
 CmdArgs.push_back("-lFortranRuntime");
 CmdArgs.push_back("-lFortranDecimal");

>From e1a472fa914ea9405be6589e89fbe8201448600f Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Fri, 1 Dec 2023 15:10:29 -0600
Subject: [PATCH 3/6] Cleanup and simplify the code a bit

---
 clang/lib/Driver/ToolChains/CommonArgs.cpp | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp 
b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 2899f07cb7490..f0e3df2a63ae9 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ 

[flang] [clang] [flang][driver] Add -fno-fortran-main (link time) option to remove Fortran_main from link line (PR #74139)

[Michael Klemm via cfe-commits]

https://github.com/mjklemm updated 
https://github.com/llvm/llvm-project/pull/74139

>From 2e41335a7de3d2efa88eacee659172a3b9525e45 Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Fri, 1 Dec 2023 21:41:44 +0100
Subject: [PATCH 1/5] Add -fno-fortran-main driver option

---
 clang/include/clang/Driver/Options.td | 4 
 1 file changed, 4 insertions(+)

diff --git a/clang/include/clang/Driver/Options.td 
b/clang/include/clang/Driver/Options.td
index 19d04e82aed4d..aa26344f67b31 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -6345,6 +6345,10 @@ def J : JoinedOrSeparate<["-"], "J">,
   Group,
   Alias;
 
+def no_fortran_main : Flag<["-"], "fno-fortran-main">,
+  Visibility<[FlangOption]>, Group,
+  HelpText<"Don't link in Fortran main">;
+
 
//===--===//
 // FC1 Options
 
//===--===//

>From 44b684ae43a6da37bb56c5b699628c6807257ad9 Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Fri, 1 Dec 2023 21:42:09 +0100
Subject: [PATCH 2/5] Skip linking Fortran_main.a if -fno-fortran-main is
 present

---
 clang/lib/Driver/ToolChains/CommonArgs.cpp | 46 --
 1 file changed, 25 insertions(+), 21 deletions(-)

diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp 
b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 0ae8e2dce32e9..2899f07cb7490 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -1116,33 +1116,37 @@ bool tools::addOpenMPRuntime(ArgStringList , 
const ToolChain ,
   return true;
 }
 
+// TODO: add -fno-fortran-main option and check it in this function.
 void tools::addFortranRuntimeLibs(const ToolChain , const ArgList ,
   llvm::opt::ArgStringList ) {
   // These are handled earlier on Windows by telling the frontend driver to add
   // the correct libraries to link against as dependents in the object file.
   if (!TC.getTriple().isKnownWindowsMSVCEnvironment()) {
-// The --whole-archive option needs to be part of the link line to
-// make sure that the main() function from Fortran_main.a is pulled
-// in by the linker.  Determine if --whole-archive is active when
-// flang will try to link Fortran_main.a.  If it is, don't add the
-// --whole-archive flag to the link line.  If it's not, add a proper
-// --whole-archive/--no-whole-archive bracket to the link line.
-bool WholeArchiveActive = false;
-for (auto *Arg : Args.filtered(options::OPT_Wl_COMMA))
-  if (Arg)
-for (StringRef ArgValue : Arg->getValues()) {
-  if (ArgValue == "--whole-archive")
-WholeArchiveActive = true;
-  if (ArgValue == "--no-whole-archive")
-WholeArchiveActive = false;
-}
-
-if (!WholeArchiveActive)
-  CmdArgs.push_back("--whole-archive");
-CmdArgs.push_back("-lFortran_main");
-if (!WholeArchiveActive)
-  CmdArgs.push_back("--no-whole-archive");
+// if -fno-fortran-main has been passed, skip linking Fortran_main.a
+bool DontLinkFortranMain = Args.getLastArg(options::OPT_no_fortran_main) 
!= nullptr;
+if (!DontLinkFortranMain) {
+  // The --whole-archive option needs to be part of the link line to
+  // make sure that the main() function from Fortran_main.a is pulled
+  // in by the linker.  Determine if --whole-archive is active when
+  // flang will try to link Fortran_main.a.  If it is, don't add the
+  // --whole-archive flag to the link line.  If it's not, add a proper
+  // --whole-archive/--no-whole-archive bracket to the link line.
+  bool WholeArchiveActive = false;
+  for (auto *Arg : Args.filtered(options::OPT_Wl_COMMA))
+if (Arg)
+  for (StringRef ArgValue : Arg->getValues()) {
+if (ArgValue == "--whole-archive")
+  WholeArchiveActive = true;
+if (ArgValue == "--no-whole-archive")
+  WholeArchiveActive = false;
+  }
 
+  if (!WholeArchiveActive)
+CmdArgs.push_back("--whole-archive");
+  CmdArgs.push_back("-lFortran_main");
+  if (!WholeArchiveActive)
+CmdArgs.push_back("--no-whole-archive");
+}
 // Perform regular linkage of the remaining runtime libraries.
 CmdArgs.push_back("-lFortranRuntime");
 CmdArgs.push_back("-lFortranDecimal");

>From e1a472fa914ea9405be6589e89fbe8201448600f Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Fri, 1 Dec 2023 15:10:29 -0600
Subject: [PATCH 3/5] Cleanup and simplify the code a bit

---
 clang/lib/Driver/ToolChains/CommonArgs.cpp | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp 
b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 2899f07cb7490..f0e3df2a63ae9 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ 

[flang] [clang] [flang][driver] Add -fno-fortran-main (link time) option to remove Fortran_main from link line (PR #74139)

[Michael Klemm via cfe-commits]

mjklemm wrote:

> I think this solution is fine, at least in the short term.
> 
> I had a think after reviewing the initial patch and looking at the failure 
> that @tblah showed in #73124; my thoughts are that the “correct” way of doing 
> this would be instead of linking Fortran_main all the time, we could insert a 
> linker directive in the object file containing the program statement. That 
> way we would only link Fortran_main when there is actually a program 
> statement in the Fortran. However that’s more work and would need a bit more 
> thought anyway so we at least need something like this or the revert in the 
> interim.

That sounds good!  For now, the code should effectively avoid linking 
Fortran_main on Linux and Windows if -fno-fortran-main is present.

https://github.com/llvm/llvm-project/pull/74139
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[flang] [clang] [flang][driver] Add -fno-fortran-main (link time) option to remove Fortran_main from link line (PR #74139)

[Michael Klemm via cfe-commits]

https://github.com/mjklemm updated 
https://github.com/llvm/llvm-project/pull/74139

>From 2e41335a7de3d2efa88eacee659172a3b9525e45 Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Fri, 1 Dec 2023 21:41:44 +0100
Subject: [PATCH 1/5] Add -fno-fortran-main driver option

---
 clang/include/clang/Driver/Options.td | 4 
 1 file changed, 4 insertions(+)

diff --git a/clang/include/clang/Driver/Options.td 
b/clang/include/clang/Driver/Options.td
index 19d04e82aed4d..aa26344f67b31 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -6345,6 +6345,10 @@ def J : JoinedOrSeparate<["-"], "J">,
   Group,
   Alias;
 
+def no_fortran_main : Flag<["-"], "fno-fortran-main">,
+  Visibility<[FlangOption]>, Group,
+  HelpText<"Don't link in Fortran main">;
+
 
//===--===//
 // FC1 Options
 
//===--===//

>From 44b684ae43a6da37bb56c5b699628c6807257ad9 Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Fri, 1 Dec 2023 21:42:09 +0100
Subject: [PATCH 2/5] Skip linking Fortran_main.a if -fno-fortran-main is
 present

---
 clang/lib/Driver/ToolChains/CommonArgs.cpp | 46 --
 1 file changed, 25 insertions(+), 21 deletions(-)

diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp 
b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 0ae8e2dce32e9..2899f07cb7490 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -1116,33 +1116,37 @@ bool tools::addOpenMPRuntime(ArgStringList , 
const ToolChain ,
   return true;
 }
 
+// TODO: add -fno-fortran-main option and check it in this function.
 void tools::addFortranRuntimeLibs(const ToolChain , const ArgList ,
   llvm::opt::ArgStringList ) {
   // These are handled earlier on Windows by telling the frontend driver to add
   // the correct libraries to link against as dependents in the object file.
   if (!TC.getTriple().isKnownWindowsMSVCEnvironment()) {
-// The --whole-archive option needs to be part of the link line to
-// make sure that the main() function from Fortran_main.a is pulled
-// in by the linker.  Determine if --whole-archive is active when
-// flang will try to link Fortran_main.a.  If it is, don't add the
-// --whole-archive flag to the link line.  If it's not, add a proper
-// --whole-archive/--no-whole-archive bracket to the link line.
-bool WholeArchiveActive = false;
-for (auto *Arg : Args.filtered(options::OPT_Wl_COMMA))
-  if (Arg)
-for (StringRef ArgValue : Arg->getValues()) {
-  if (ArgValue == "--whole-archive")
-WholeArchiveActive = true;
-  if (ArgValue == "--no-whole-archive")
-WholeArchiveActive = false;
-}
-
-if (!WholeArchiveActive)
-  CmdArgs.push_back("--whole-archive");
-CmdArgs.push_back("-lFortran_main");
-if (!WholeArchiveActive)
-  CmdArgs.push_back("--no-whole-archive");
+// if -fno-fortran-main has been passed, skip linking Fortran_main.a
+bool DontLinkFortranMain = Args.getLastArg(options::OPT_no_fortran_main) 
!= nullptr;
+if (!DontLinkFortranMain) {
+  // The --whole-archive option needs to be part of the link line to
+  // make sure that the main() function from Fortran_main.a is pulled
+  // in by the linker.  Determine if --whole-archive is active when
+  // flang will try to link Fortran_main.a.  If it is, don't add the
+  // --whole-archive flag to the link line.  If it's not, add a proper
+  // --whole-archive/--no-whole-archive bracket to the link line.
+  bool WholeArchiveActive = false;
+  for (auto *Arg : Args.filtered(options::OPT_Wl_COMMA))
+if (Arg)
+  for (StringRef ArgValue : Arg->getValues()) {
+if (ArgValue == "--whole-archive")
+  WholeArchiveActive = true;
+if (ArgValue == "--no-whole-archive")
+  WholeArchiveActive = false;
+  }
 
+  if (!WholeArchiveActive)
+CmdArgs.push_back("--whole-archive");
+  CmdArgs.push_back("-lFortran_main");
+  if (!WholeArchiveActive)
+CmdArgs.push_back("--no-whole-archive");
+}
 // Perform regular linkage of the remaining runtime libraries.
 CmdArgs.push_back("-lFortranRuntime");
 CmdArgs.push_back("-lFortranDecimal");

>From e1a472fa914ea9405be6589e89fbe8201448600f Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Fri, 1 Dec 2023 15:10:29 -0600
Subject: [PATCH 3/5] Cleanup and simplify the code a bit

---
 clang/lib/Driver/ToolChains/CommonArgs.cpp | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp 
b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 2899f07cb7490..f0e3df2a63ae9 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ 

[flang] [clang] [flang][driver] Add -fno-fortran-main (link time) option to remove Fortran_main from link line (PR #74139)

[Michael Klemm via cfe-commits]

https://github.com/mjklemm edited 
https://github.com/llvm/llvm-project/pull/74139
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[flang] [clang] [flang][driver][RFC] Add -fno-fortran-main (link time) option to remove Fortran_main from link line (PR #74139)

[Michael Klemm via cfe-commits]

https://github.com/mjklemm updated 
https://github.com/llvm/llvm-project/pull/74139

>From 2e41335a7de3d2efa88eacee659172a3b9525e45 Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Fri, 1 Dec 2023 21:41:44 +0100
Subject: [PATCH 1/4] Add -fno-fortran-main driver option

---
 clang/include/clang/Driver/Options.td | 4 
 1 file changed, 4 insertions(+)

diff --git a/clang/include/clang/Driver/Options.td 
b/clang/include/clang/Driver/Options.td
index 19d04e82aed4d68..aa26344f67b3132 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -6345,6 +6345,10 @@ def J : JoinedOrSeparate<["-"], "J">,
   Group,
   Alias;
 
+def no_fortran_main : Flag<["-"], "fno-fortran-main">,
+  Visibility<[FlangOption]>, Group,
+  HelpText<"Don't link in Fortran main">;
+
 
//===--===//
 // FC1 Options
 
//===--===//

>From 44b684ae43a6da37bb56c5b699628c6807257ad9 Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Fri, 1 Dec 2023 21:42:09 +0100
Subject: [PATCH 2/4] Skip linking Fortran_main.a if -fno-fortran-main is
 present

---
 clang/lib/Driver/ToolChains/CommonArgs.cpp | 46 --
 1 file changed, 25 insertions(+), 21 deletions(-)

diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp 
b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 0ae8e2dce32e94a..2899f07cb7490ca 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -1116,33 +1116,37 @@ bool tools::addOpenMPRuntime(ArgStringList , 
const ToolChain ,
   return true;
 }
 
+// TODO: add -fno-fortran-main option and check it in this function.
 void tools::addFortranRuntimeLibs(const ToolChain , const ArgList ,
   llvm::opt::ArgStringList ) {
   // These are handled earlier on Windows by telling the frontend driver to add
   // the correct libraries to link against as dependents in the object file.
   if (!TC.getTriple().isKnownWindowsMSVCEnvironment()) {
-// The --whole-archive option needs to be part of the link line to
-// make sure that the main() function from Fortran_main.a is pulled
-// in by the linker.  Determine if --whole-archive is active when
-// flang will try to link Fortran_main.a.  If it is, don't add the
-// --whole-archive flag to the link line.  If it's not, add a proper
-// --whole-archive/--no-whole-archive bracket to the link line.
-bool WholeArchiveActive = false;
-for (auto *Arg : Args.filtered(options::OPT_Wl_COMMA))
-  if (Arg)
-for (StringRef ArgValue : Arg->getValues()) {
-  if (ArgValue == "--whole-archive")
-WholeArchiveActive = true;
-  if (ArgValue == "--no-whole-archive")
-WholeArchiveActive = false;
-}
-
-if (!WholeArchiveActive)
-  CmdArgs.push_back("--whole-archive");
-CmdArgs.push_back("-lFortran_main");
-if (!WholeArchiveActive)
-  CmdArgs.push_back("--no-whole-archive");
+// if -fno-fortran-main has been passed, skip linking Fortran_main.a
+bool DontLinkFortranMain = Args.getLastArg(options::OPT_no_fortran_main) 
!= nullptr;
+if (!DontLinkFortranMain) {
+  // The --whole-archive option needs to be part of the link line to
+  // make sure that the main() function from Fortran_main.a is pulled
+  // in by the linker.  Determine if --whole-archive is active when
+  // flang will try to link Fortran_main.a.  If it is, don't add the
+  // --whole-archive flag to the link line.  If it's not, add a proper
+  // --whole-archive/--no-whole-archive bracket to the link line.
+  bool WholeArchiveActive = false;
+  for (auto *Arg : Args.filtered(options::OPT_Wl_COMMA))
+if (Arg)
+  for (StringRef ArgValue : Arg->getValues()) {
+if (ArgValue == "--whole-archive")
+  WholeArchiveActive = true;
+if (ArgValue == "--no-whole-archive")
+  WholeArchiveActive = false;
+  }
 
+  if (!WholeArchiveActive)
+CmdArgs.push_back("--whole-archive");
+  CmdArgs.push_back("-lFortran_main");
+  if (!WholeArchiveActive)
+CmdArgs.push_back("--no-whole-archive");
+}
 // Perform regular linkage of the remaining runtime libraries.
 CmdArgs.push_back("-lFortranRuntime");
 CmdArgs.push_back("-lFortranDecimal");

>From e1a472fa914ea9405be6589e89fbe8201448600f Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Fri, 1 Dec 2023 15:10:29 -0600
Subject: [PATCH 3/4] Cleanup and simplify the code a bit

---
 clang/lib/Driver/ToolChains/CommonArgs.cpp | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp 
b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 2899f07cb7490ca..f0e3df2a63ae989 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ 

[clang] [flang][driver][RFC] Add -fno-fortran-main (link time) option to remove Fortran_main from link line (PR #74139)

[Michael Klemm via cfe-commits]

https://github.com/mjklemm edited 
https://github.com/llvm/llvm-project/pull/74139
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[clang] [flang][driver] Add -fno-fortran-main (link time) option to remove Fortran_main from link line (PR #74139)

[Michael Klemm via cfe-commits]

mjklemm wrote:

This WIP for now, as I still have to make the changes for MSVC.  But it's good 
enough to discuss if this is a viable solution.

https://github.com/llvm/llvm-project/pull/74139
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[flang] [clang] Revert "[flang][Driver] Let the linker fail on multiple definitions of main()" (PR #74120)

[Michael Klemm via cfe-commits]

mjklemm wrote:

I have opened PR #74139 to provide an alternate solution to this.  Please have 
a look there.

@tblah Would you mind trying this new option with one application code to see 
if that will help? 

https://github.com/llvm/llvm-project/pull/74120
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[clang] [flang][driver] Add -fno-fortran-main (link time) option to remove Fortran_main from link line (PR #74139)

[Michael Klemm via cfe-commits]

https://github.com/mjklemm created 
https://github.com/llvm/llvm-project/pull/74139

This is related to PR #74120 and (merged) PR #73124.

This PR adds the `-fno-fortran-main` command line option to remove 
`Fortran_main.a` from the link and to allow for linking Fortran code w/o 
program unit with C/C++ translation units that provide the `main()` entrypoint.

>From 2e41335a7de3d2efa88eacee659172a3b9525e45 Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Fri, 1 Dec 2023 21:41:44 +0100
Subject: [PATCH 1/2] Add -fno-fortran-main driver option

---
 clang/include/clang/Driver/Options.td | 4 
 1 file changed, 4 insertions(+)

diff --git a/clang/include/clang/Driver/Options.td 
b/clang/include/clang/Driver/Options.td
index 19d04e82aed4d68..aa26344f67b3132 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -6345,6 +6345,10 @@ def J : JoinedOrSeparate<["-"], "J">,
   Group,
   Alias;
 
+def no_fortran_main : Flag<["-"], "fno-fortran-main">,
+  Visibility<[FlangOption]>, Group,
+  HelpText<"Don't link in Fortran main">;
+
 
//===--===//
 // FC1 Options
 
//===--===//

>From 44b684ae43a6da37bb56c5b699628c6807257ad9 Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Fri, 1 Dec 2023 21:42:09 +0100
Subject: [PATCH 2/2] Skip linking Fortran_main.a if -fno-fortran-main is
 present

---
 clang/lib/Driver/ToolChains/CommonArgs.cpp | 46 --
 1 file changed, 25 insertions(+), 21 deletions(-)

diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp 
b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 0ae8e2dce32e94a..2899f07cb7490ca 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -1116,33 +1116,37 @@ bool tools::addOpenMPRuntime(ArgStringList , 
const ToolChain ,
   return true;
 }
 
+// TODO: add -fno-fortran-main option and check it in this function.
 void tools::addFortranRuntimeLibs(const ToolChain , const ArgList ,
   llvm::opt::ArgStringList ) {
   // These are handled earlier on Windows by telling the frontend driver to add
   // the correct libraries to link against as dependents in the object file.
   if (!TC.getTriple().isKnownWindowsMSVCEnvironment()) {
-// The --whole-archive option needs to be part of the link line to
-// make sure that the main() function from Fortran_main.a is pulled
-// in by the linker.  Determine if --whole-archive is active when
-// flang will try to link Fortran_main.a.  If it is, don't add the
-// --whole-archive flag to the link line.  If it's not, add a proper
-// --whole-archive/--no-whole-archive bracket to the link line.
-bool WholeArchiveActive = false;
-for (auto *Arg : Args.filtered(options::OPT_Wl_COMMA))
-  if (Arg)
-for (StringRef ArgValue : Arg->getValues()) {
-  if (ArgValue == "--whole-archive")
-WholeArchiveActive = true;
-  if (ArgValue == "--no-whole-archive")
-WholeArchiveActive = false;
-}
-
-if (!WholeArchiveActive)
-  CmdArgs.push_back("--whole-archive");
-CmdArgs.push_back("-lFortran_main");
-if (!WholeArchiveActive)
-  CmdArgs.push_back("--no-whole-archive");
+// if -fno-fortran-main has been passed, skip linking Fortran_main.a
+bool DontLinkFortranMain = Args.getLastArg(options::OPT_no_fortran_main) 
!= nullptr;
+if (!DontLinkFortranMain) {
+  // The --whole-archive option needs to be part of the link line to
+  // make sure that the main() function from Fortran_main.a is pulled
+  // in by the linker.  Determine if --whole-archive is active when
+  // flang will try to link Fortran_main.a.  If it is, don't add the
+  // --whole-archive flag to the link line.  If it's not, add a proper
+  // --whole-archive/--no-whole-archive bracket to the link line.
+  bool WholeArchiveActive = false;
+  for (auto *Arg : Args.filtered(options::OPT_Wl_COMMA))
+if (Arg)
+  for (StringRef ArgValue : Arg->getValues()) {
+if (ArgValue == "--whole-archive")
+  WholeArchiveActive = true;
+if (ArgValue == "--no-whole-archive")
+  WholeArchiveActive = false;
+  }
 
+  if (!WholeArchiveActive)
+CmdArgs.push_back("--whole-archive");
+  CmdArgs.push_back("-lFortran_main");
+  if (!WholeArchiveActive)
+CmdArgs.push_back("--no-whole-archive");
+}
 // Perform regular linkage of the remaining runtime libraries.
 CmdArgs.push_back("-lFortranRuntime");
 CmdArgs.push_back("-lFortranDecimal");

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[clang] [flang] Revert "[flang][Driver] Let the linker fail on multiple definitions of main()" (PR #74120)

[Michael Klemm via cfe-commits]

mjklemm wrote:

BTW, flang legacy has this: `  -fno-fortran-main   Don't link in Fortran 
main` 

Adding that command line option might be the right choice.  If everyone agrees, 
I can see if I can get this added.

https://github.com/llvm/llvm-project/pull/74120
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[clang] [flang] Revert "[flang][Driver] Let the linker fail on multiple definitions of main()" (PR #74120)

[Michael Klemm via cfe-commits]

mjklemm wrote:

> For what it's worth, `armflang` follows gfortran's behavior.

So does the "old legacy flang", which I guess is the basis for armflang.  
AOCC's flang shows the same behavior.


> As there isn't consensus amongst fortran compilers, I'm unsure which behavior 
> we should follow. What do other's think?

I guess, we could agree that the current behavior of flang-new ignoring the 
Fortran program unit is present, is not correct either. :-)

Could please see if `-Wl,--allow-multiple-definition` would help to resolve the 
issue in the application?

https://github.com/llvm/llvm-project/pull/74120
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[clang] [flang] Revert "[flang][Driver] Let the linker fail on multiple definitions of main()" (PR #74120)

[Michael Klemm via cfe-commits]

mjklemm wrote:

The above fails with ifort/ifx:

```
[2023-12-01 19:00:56 CET] iris ~/tm*/fo*/ftn_main_dupes [0:0] (main *=)> cat > 
ftn.f90
function pow(a, b)
  real :: a, b, pow
  pow = a ** b
end function
[2023-12-01 19:01:03 CET] iris ~/tm*/fo*/ftn_main_dupes [0:0] (main *=)> !if
[2023-12-01 19:01:04 CET] iris ~/tm*/fo*/ftn_main_dupes [0:0] (main *=)> ifx -o 
ftn.o -c ftn.f90 && icc -o prg.o -c prg.c && ifx -o bla prg.o ftn.o
icc: remark #10441: The Intel(R) C++ Compiler Classic (ICC) is deprecated and 
will be removed from product release in the second half of 2023. The Intel(R) 
oneAPI DPC++/C++ Compiler (ICX) is the recommended compiler moving forward. 
Please transition to use this compiler. Use '-diag-disable=10441' to disable 
this message.
ld: prg.o: in function `main':
prg.c:(.text+0x0): multiple definition of `main'; 
/net/software/x86_64/oneapi/compiler/2023.1.0/linux/compiler/lib/intel64_lin/for_main.o:for_main.c:(.text+0x0):
 first defined here
ld: 
/net/software/x86_64/oneapi/compiler/2023.1.0/linux/compiler/lib/intel64_lin/for_main.o:
 in function `main':
for_main.c:(.text+0x19): undefined reference to `MAIN__'
[2023-12-01 19:01:24 CET] [1] iris ~/tm*/fo*/ftn_main_dupes [0:0] (main *=)> 
cat prg.c
int main(void) {
  // call fortran code
  return 0;
}
[2023-12-01 19:01:27 CET] iris ~/tm*/fo*/ftn_main_dupes [0:0] (main *=)> cat 
ftn.f90
function pow(a, b)
  real :: a, b, pow
  pow = a ** b
end function
[2023-12-01 19:01:31 CET] iris ~/tm*/fo*/ftn_main_dupes [0:0] (main *=)> ifx -o 
ftn.o -c ftn.f90 && icc -o prg.o -c prg.c && ifx -o bla prg.o ftn.o
icc: remark #10441: The Intel(R) C++ Compiler Classic (ICC) is deprecated and 
will be removed from product release in the second half of 2023. The Intel(R) 
oneAPI DPC++/C++ Compiler (ICX) is the recommended compiler moving forward. 
Please transition to use this compiler. Use '-diag-disable=10441' to disable 
this message.
ld: prg.o: in function `main':
prg.c:(.text+0x0): multiple definition of `main'; 
/net/software/x86_64/oneapi/compiler/2023.1.0/linux/compiler/lib/intel64_lin/for_main.o:for_main.c:(.text+0x0):
 first defined here
ld: 
/net/software/x86_64/oneapi/compiler/2023.1.0/linux/compiler/lib/intel64_lin/for_main.o:
 in function `main':
for_main.c:(.text+0x19): undefined reference to `MAIN__'
[2023-12-01 19:01:34 CET] [1] iris ~/tm*/fo*/ftn_main_dupes [0:0] (main *=)> 
ifort -o ftn.o -c ftn.f90 && icc -o prg.o -c prg.c && ifort -o bla prg.o ftn.o
icc: remark #10441: The Intel(R) C++ Compiler Classic (ICC) is deprecated and 
will be removed from product release in the second half of 2023. The Intel(R) 
oneAPI DPC++/C++ Compiler (ICX) is the recommended compiler moving forward. 
Please transition to use this compiler. Use '-diag-disable=10441' to disable 
this message.
ld: prg.o: in function `main':
prg.c:(.text+0x0): multiple definition of `main'; 
/net/software/x86_64/oneapi/compiler/2023.1.0/linux/bin/intel64/../../compiler/lib/intel64_lin/for_main.o:for_main.c:(.text+0x0):
 first defined here
ld: 
/net/software/x86_64/oneapi/compiler/2023.1.0/linux/bin/intel64/../../compiler/lib/intel64_lin/for_main.o:
 in function `main':
for_main.c:(.text+0x19): undefined reference to `MAIN__'
```

To get gfortran's behavior one could also use `-Wl,--allow-multiple-definition` 
which would then allow the linker to pick the C `main` function and ignore the 
`main` function from Fortran_main.a



https://github.com/llvm/llvm-project/pull/74120
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[flang] [clang] [flang][Driver] Let the linker fail on multiple definitions of main() (PR #73124)

[Michael Klemm via cfe-commits]

mjklemm wrote:

> That example is different because you used `program` in the fortran source. 
> The use case here is applications which implement `main` in C then call into 
> fortran code

Do you have a link line for ifort?  It seems that your example fails with 
ifort, but indeed works with gfortran.  The simple reason is that gfortran 
emits a main function into the translation unit if it has a program unit.  If 
it does not, the main function is not generated.

https://github.com/llvm/llvm-project/pull/73124
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[clang] [flang] [flang][Driver] Let the linker fail on multiple definitions of main() (PR #73124)

[Michael Klemm via cfe-commits]

mjklemm wrote:

Ok, got it!  I'm fione with reverting this patch and seeking a better solution.

https://github.com/llvm/llvm-project/pull/73124
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[flang] [clang] [flang][Driver] Let the linker fail on multiple definitions of main() (PR #73124)

[Michael Klemm via cfe-commits]

mjklemm wrote:

Here's the reproducer on my system:

```
[2023-12-01 18:36:31 CET] iris ~/tm*/fo*/ftn_main_dupes [0:0] (main *=)> 
gfortran -o ftn.o -c ftn.f90 && gcc -o prg.o -c prg.c && gfortran -o ./bla 
ftn.o prg.o
/usr/bin/ld: prg.o: in function `main':
prg.c:(.text+0x0): multiple definition of `main'; ftn.o:ftn.f90:(.text+0x8f): 
first defined here
collect2: error: ld returned 1 exit status
[2023-12-01 18:36:34 CET] [1] iris ~/tm*/fo*/ftn_main_dupes [0:0] (main *=)> 
cat prg.c
#include 

int main(int argc, char * argv[]) {
printf("Hello from C [%s]\n", __FUNCTION__);
return 0;
}
[2023-12-01 18:36:37 CET] iris ~/tm*/fo*/ftn_main_dupes [0:0] (main *=)> cat 
ftn.f90
program ftn
print '(A)', 'Hello from Fortran'
end program ftn
[2023-12-01 18:36:40 CET] iris ~/tm*/fo*/ftn_main_dupes [0:0] (main *=)> 
gfortran --version
GNU Fortran (Ubuntu 11.4.0-1ubuntu1~22.04) 11.4.0
Copyright (C) 2021 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
```

https://github.com/llvm/llvm-project/pull/73124
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[flang] [clang] [flang][Driver] Let the linker fail on multiple definitions of main() (PR #73124)

[Michael Klemm via cfe-commits]

mjklemm wrote:

gfortran and also ifort should fail for codes that have both a program unit and 
a makn() function coming from C. 

These compilers have a main() function that calls into the Fortran program unit 
and link that via an object file. 

Id be interested to see the link line for these compilers before we revert the 
PR.  The behavior now should actually be consistent with these other compilers. 

https://github.com/llvm/llvm-project/pull/73124
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[clang] [flang] [flang][Driver] Let the linker fail on multiple definitions of main() (PR #73124)

[Michael Klemm via cfe-commits]

mjklemm wrote:

Thanks all for your reviews and the all the feedback you have provided!  Much 
appreciated!

https://github.com/llvm/llvm-project/pull/73124
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[clang] [flang] [flang][Driver] Let the linker fail on multiple definitions of main() (PR #73124)

[Michael Klemm via cfe-commits]

https://github.com/mjklemm updated 
https://github.com/llvm/llvm-project/pull/73124

>From 2a2693364cb8e9b657b9ff54aa78df0466b55fe4 Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Wed, 22 Nov 2023 14:22:20 +0100
Subject: [PATCH 01/16] Let the linker fail on multiple definitions of main()

---
 clang/lib/Driver/ToolChains/CommonArgs.cpp | 15 ++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp 
b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 1f31c6395206ee8..740ae71177b2c3a 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -982,7 +982,20 @@ void tools::addFortranRuntimeLibs(const ToolChain ,
   // These are handled earlier on Windows by telling the frontend driver to add
   // the correct libraries to link against as dependents in the object file.
   if (!TC.getTriple().isKnownWindowsMSVCEnvironment()) {
+// --whole-archive needs to be part of the link line to make sure
+// that the main() function from Fortran_main.a is pulled in by
+// the linker.
+//
+// We are using this --whole-archive/--no-whole-archive bracket w/o
+// any further checks, because -Wl,--whole-archive at the flang-new new
+// line will not sucessfully complete, unless the user correctly specified
+// -Wl,--no-whole-archive (e.g., -Wl,--whole-archive -ldummy
+// -Wl,--no-whole-archive).
+CmdArgs.push_back("--whole-archive");
 CmdArgs.push_back("-lFortran_main");
+CmdArgs.push_back("--no-whole-archive");
+
+// Perform regular linkage of the remaining runtime libraries.
 CmdArgs.push_back("-lFortranRuntime");
 CmdArgs.push_back("-lFortranDecimal");
   }
@@ -993,7 +1006,7 @@ void tools::addFortranRuntimeLibraryPath(const ToolChain 
,
  ArgStringList ) {
   // Default to the /../lib directory. This works fine on the
   // platforms that we have tested so far. We will probably have to re-fine
-  // this in the future. In particular, on some platforms, we may need to use
+  // this in the future. In particular, on some platforms, we may need to useq
   // lib64 instead of lib.
   SmallString<256> DefaultLibPath =
   llvm::sys::path::parent_path(TC.getDriver().Dir);

>From 0d652282f4dbed2dde11df53ead3e6c8b6856bed Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Wed, 22 Nov 2023 15:18:51 +0100
Subject: [PATCH 02/16] Improve comments and remove accidental typo

---
 clang/lib/Driver/ToolChains/CommonArgs.cpp | 10 +-
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp 
b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 740ae71177b2c3a..464a87737de062c 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -987,10 +987,10 @@ void tools::addFortranRuntimeLibs(const ToolChain ,
 // the linker.
 //
 // We are using this --whole-archive/--no-whole-archive bracket w/o
-// any further checks, because -Wl,--whole-archive at the flang-new new
-// line will not sucessfully complete, unless the user correctly specified
-// -Wl,--no-whole-archive (e.g., -Wl,--whole-archive -ldummy
-// -Wl,--no-whole-archive).
+// any further checks, because -Wl,--whole-archive at the flang
+// driver's link line will not sucessfully complete, unless the user
+// correctly specified -Wl,--whole-archive/-Wl,--no-whole-archive
+// (e.g., -Wl,--whole-archive -ldummy -Wl,--no-whole-archive).
 CmdArgs.push_back("--whole-archive");
 CmdArgs.push_back("-lFortran_main");
 CmdArgs.push_back("--no-whole-archive");
@@ -1006,7 +1006,7 @@ void tools::addFortranRuntimeLibraryPath(const ToolChain 
,
  ArgStringList ) {
   // Default to the /../lib directory. This works fine on the
   // platforms that we have tested so far. We will probably have to re-fine
-  // this in the future. In particular, on some platforms, we may need to useq
+  // this in the future. In particular, on some platforms, we may need to use
   // lib64 instead of lib.
   SmallString<256> DefaultLibPath =
   llvm::sys::path::parent_path(TC.getDriver().Dir);

>From 39612e237cb815cf4ea0120027783d35304bcb6b Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Wed, 22 Nov 2023 20:26:02 +0100
Subject: [PATCH 03/16] Correct link line test for flang-new (for Linux)

---
 flang/test/Driver/linker-flags.f90 | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/flang/test/Driver/linker-flags.f90 
b/flang/test/Driver/linker-flags.f90
index 85c4d60b3f09862..ea91946316cfaa6 100644
--- a/flang/test/Driver/linker-flags.f90
+++ b/flang/test/Driver/linker-flags.f90
@@ -28,7 +28,7 @@
 !   executable and may find the GNU linker from MinGW or Cygwin.
 ! UNIX-LABEL:  "{{.*}}ld{{(\.exe)?}}"
 ! UNIX-SAME: "[[object_file]]"
-! UNIX-SAME: "-lFortran_main" "-lFortranRuntime" 

[clang] [flang] [flang][Driver] Let the linker fail on multiple definitions of main() (PR #73124)

[Michael Klemm via cfe-commits]

@@ -977,14 +977,61 @@ bool tools::addOpenMPRuntime(ArgStringList , 
const ToolChain ,
   return true;
 }
 
-void tools::addFortranRuntimeLibs(const ToolChain ,
+void tools::addFortranRuntimeLibs(const ToolChain , const ArgList ,
   llvm::opt::ArgStringList ) {
   // These are handled earlier on Windows by telling the frontend driver to add
   // the correct libraries to link against as dependents in the object file.
   if (!TC.getTriple().isKnownWindowsMSVCEnvironment()) {
+// The --whole-archive option needs to be part of the link line to
+// make sure that the main() function from Fortran_main.a is pulled
+// in by the linker.  Determine if --whole-archive is active when
+// flang will try to link Fortran_main.a.  If it is, don't add the
+// --whole-archive flag to the link line.  If it's not, add a proper
+// --whole-archive/--no-whole-archive bracket to the link line.
+bool NeedWholeArchive = true;
+auto * Arg = Args.getLastArg(options::OPT_Wl_COMMA);

mjklemm wrote:

Should be fixed, too.

https://github.com/llvm/llvm-project/pull/73124
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[clang] [flang] [flang][Driver] Let the linker fail on multiple definitions of main() (PR #73124)

[Michael Klemm via cfe-commits]

@@ -977,14 +977,61 @@ bool tools::addOpenMPRuntime(ArgStringList , 
const ToolChain ,
   return true;
 }
 
-void tools::addFortranRuntimeLibs(const ToolChain ,
+void tools::addFortranRuntimeLibs(const ToolChain , const ArgList ,
   llvm::opt::ArgStringList ) {
   // These are handled earlier on Windows by telling the frontend driver to add
   // the correct libraries to link against as dependents in the object file.
   if (!TC.getTriple().isKnownWindowsMSVCEnvironment()) {
+// The --whole-archive option needs to be part of the link line to
+// make sure that the main() function from Fortran_main.a is pulled
+// in by the linker.  Determine if --whole-archive is active when
+// flang will try to link Fortran_main.a.  If it is, don't add the
+// --whole-archive flag to the link line.  If it's not, add a proper
+// --whole-archive/--no-whole-archive bracket to the link line.
+bool NeedWholeArchive = true;
+auto * Arg = Args.getLastArg(options::OPT_Wl_COMMA);
+for (StringRef ArgValue : llvm::reverse(Arg->getValues())) {
+  if (ArgValue == "--whole-archive") {
+NeedWholeArchive = false;
+break;
+  }

mjklemm wrote:

Should be fixed now.

https://github.com/llvm/llvm-project/pull/73124
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[flang] [clang] [flang][Driver] Let the linker fail on multiple definitions of main() (PR #73124)

[Michael Klemm via cfe-commits]

https://github.com/mjklemm updated 
https://github.com/llvm/llvm-project/pull/73124

>From 2a2693364cb8e9b657b9ff54aa78df0466b55fe4 Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Wed, 22 Nov 2023 14:22:20 +0100
Subject: [PATCH 01/16] Let the linker fail on multiple definitions of main()

---
 clang/lib/Driver/ToolChains/CommonArgs.cpp | 15 ++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp 
b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 1f31c6395206ee8..740ae71177b2c3a 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -982,7 +982,20 @@ void tools::addFortranRuntimeLibs(const ToolChain ,
   // These are handled earlier on Windows by telling the frontend driver to add
   // the correct libraries to link against as dependents in the object file.
   if (!TC.getTriple().isKnownWindowsMSVCEnvironment()) {
+// --whole-archive needs to be part of the link line to make sure
+// that the main() function from Fortran_main.a is pulled in by
+// the linker.
+//
+// We are using this --whole-archive/--no-whole-archive bracket w/o
+// any further checks, because -Wl,--whole-archive at the flang-new new
+// line will not sucessfully complete, unless the user correctly specified
+// -Wl,--no-whole-archive (e.g., -Wl,--whole-archive -ldummy
+// -Wl,--no-whole-archive).
+CmdArgs.push_back("--whole-archive");
 CmdArgs.push_back("-lFortran_main");
+CmdArgs.push_back("--no-whole-archive");
+
+// Perform regular linkage of the remaining runtime libraries.
 CmdArgs.push_back("-lFortranRuntime");
 CmdArgs.push_back("-lFortranDecimal");
   }
@@ -993,7 +1006,7 @@ void tools::addFortranRuntimeLibraryPath(const ToolChain 
,
  ArgStringList ) {
   // Default to the /../lib directory. This works fine on the
   // platforms that we have tested so far. We will probably have to re-fine
-  // this in the future. In particular, on some platforms, we may need to use
+  // this in the future. In particular, on some platforms, we may need to useq
   // lib64 instead of lib.
   SmallString<256> DefaultLibPath =
   llvm::sys::path::parent_path(TC.getDriver().Dir);

>From 0d652282f4dbed2dde11df53ead3e6c8b6856bed Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Wed, 22 Nov 2023 15:18:51 +0100
Subject: [PATCH 02/16] Improve comments and remove accidental typo

---
 clang/lib/Driver/ToolChains/CommonArgs.cpp | 10 +-
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp 
b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 740ae71177b2c3a..464a87737de062c 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -987,10 +987,10 @@ void tools::addFortranRuntimeLibs(const ToolChain ,
 // the linker.
 //
 // We are using this --whole-archive/--no-whole-archive bracket w/o
-// any further checks, because -Wl,--whole-archive at the flang-new new
-// line will not sucessfully complete, unless the user correctly specified
-// -Wl,--no-whole-archive (e.g., -Wl,--whole-archive -ldummy
-// -Wl,--no-whole-archive).
+// any further checks, because -Wl,--whole-archive at the flang
+// driver's link line will not sucessfully complete, unless the user
+// correctly specified -Wl,--whole-archive/-Wl,--no-whole-archive
+// (e.g., -Wl,--whole-archive -ldummy -Wl,--no-whole-archive).
 CmdArgs.push_back("--whole-archive");
 CmdArgs.push_back("-lFortran_main");
 CmdArgs.push_back("--no-whole-archive");
@@ -1006,7 +1006,7 @@ void tools::addFortranRuntimeLibraryPath(const ToolChain 
,
  ArgStringList ) {
   // Default to the /../lib directory. This works fine on the
   // platforms that we have tested so far. We will probably have to re-fine
-  // this in the future. In particular, on some platforms, we may need to useq
+  // this in the future. In particular, on some platforms, we may need to use
   // lib64 instead of lib.
   SmallString<256> DefaultLibPath =
   llvm::sys::path::parent_path(TC.getDriver().Dir);

>From 39612e237cb815cf4ea0120027783d35304bcb6b Mon Sep 17 00:00:00 2001
From: Michael Klemm 
Date: Wed, 22 Nov 2023 20:26:02 +0100
Subject: [PATCH 03/16] Correct link line test for flang-new (for Linux)

---
 flang/test/Driver/linker-flags.f90 | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/flang/test/Driver/linker-flags.f90 
b/flang/test/Driver/linker-flags.f90
index 85c4d60b3f09862..ea91946316cfaa6 100644
--- a/flang/test/Driver/linker-flags.f90
+++ b/flang/test/Driver/linker-flags.f90
@@ -28,7 +28,7 @@
 !   executable and may find the GNU linker from MinGW or Cygwin.
 ! UNIX-LABEL:  "{{.*}}ld{{(\.exe)?}}"
 ! UNIX-SAME: "[[object_file]]"
-! UNIX-SAME: "-lFortran_main" "-lFortranRuntime" 

[flang] [clang] [flang][Driver] Let the linker fail on multiple definitions of main() (PR #73124)

[Michael Klemm via cfe-commits]

@@ -977,14 +977,61 @@ bool tools::addOpenMPRuntime(ArgStringList , 
const ToolChain ,
   return true;
 }
 
-void tools::addFortranRuntimeLibs(const ToolChain ,
+void tools::addFortranRuntimeLibs(const ToolChain , const ArgList ,
   llvm::opt::ArgStringList ) {
   // These are handled earlier on Windows by telling the frontend driver to add
   // the correct libraries to link against as dependents in the object file.
   if (!TC.getTriple().isKnownWindowsMSVCEnvironment()) {
+// The --whole-archive option needs to be part of the link line to
+// make sure that the main() function from Fortran_main.a is pulled
+// in by the linker.  Determine if --whole-archive is active when
+// flang will try to link Fortran_main.a.  If it is, don't add the
+// --whole-archive flag to the link line.  If it's not, add a proper
+// --whole-archive/--no-whole-archive bracket to the link line.
+bool NeedWholeArchive = true;
+auto * Arg = Args.getLastArg(options::OPT_Wl_COMMA);

mjklemm wrote:

Right.  I'll fix this when I fixup the detecting algorithm.  The getLastArg 
thing was a red herring :-)

https://github.com/llvm/llvm-project/pull/73124
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[flang] [clang] [flang][Driver] Let the linker fail on multiple definitions of main() (PR #73124)

[Michael Klemm via cfe-commits]

@@ -977,14 +977,61 @@ bool tools::addOpenMPRuntime(ArgStringList , 
const ToolChain ,
   return true;
 }
 
-void tools::addFortranRuntimeLibs(const ToolChain ,
+void tools::addFortranRuntimeLibs(const ToolChain , const ArgList ,
   llvm::opt::ArgStringList ) {
   // These are handled earlier on Windows by telling the frontend driver to add
   // the correct libraries to link against as dependents in the object file.
   if (!TC.getTriple().isKnownWindowsMSVCEnvironment()) {
+// The --whole-archive option needs to be part of the link line to
+// make sure that the main() function from Fortran_main.a is pulled
+// in by the linker.  Determine if --whole-archive is active when
+// flang will try to link Fortran_main.a.  If it is, don't add the
+// --whole-archive flag to the link line.  If it's not, add a proper
+// --whole-archive/--no-whole-archive bracket to the link line.
+bool NeedWholeArchive = true;
+auto * Arg = Args.getLastArg(options::OPT_Wl_COMMA);
+for (StringRef ArgValue : llvm::reverse(Arg->getValues())) {
+  if (ArgValue == "--whole-archive") {
+NeedWholeArchive = false;
+break;
+  }

mjklemm wrote:

Are you sure?  The default is to modify the link line and only not do it if 
--whole-archive was found.   However, there's an actual bug now, as this goes 
is treated wrongly:

`-Wl,--whole-archive -ldummy  -Wl,-dummy`

Now, the check does not see the --whole-archive anymore.  I need to go back to 
go through all the -Wl, and see which is the last one to have something to do 
with --whole-archive.

https://github.com/llvm/llvm-project/pull/73124
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