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Fixes #50794 <https://github.com/llvm/llvm-project/issues/50794>. Reopening an
inline namespace without the `inline` keyword yields a warning:
inline namespace abc {}
namespace abc {}
namespace abc {}
<source>:2:11: warning: inline namespace reopened as a non-inline namespace
[-Winline-namespace-reopened-noninline]
namespace abc {}
^
inline
<source>:1:18: note: previous definition is here
inline namespace abc {}
^
<source>:3:11: warning: inline namespace reopened as a non-inline namespace
[-Winline-namespace-reopened-noninline]
namespace abc {}
^
inline
<source>:2:11: note: previous definition is here
namespace abc {}
^
But you'll notice that the second "previous definition is here" is actually not
helpful, because this previous definition isn't explicitly marked `inline`. I
think that the note should point to the first definition instead, which must
always <https://eel.is/c++draft/namespace.def#general-4> have the `inline` if
the namespace is supposed to be an inline namespace.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D122278
Files:
clang/lib/Sema/SemaDeclCXX.cpp
clang/test/Parser/cxx2a-inline-nested-namespace-definition.cpp
clang/test/SemaCXX/warn-inline-namespace-reopened-twice.cpp
Index: clang/test/SemaCXX/warn-inline-namespace-reopened-twice.cpp
===================================================================
--- /dev/null
+++ clang/test/SemaCXX/warn-inline-namespace-reopened-twice.cpp
@@ -0,0 +1,9 @@
+// RUN: %clang_cc1 -fsyntax-only -Wall -verify -std=c++11 %s
+
+// Regression test for #50794.
+
+// expected-note@+1 2 {{previous definition is here}}
+inline namespace X {}
+
+namespace X {} // expected-warning {{inline namespace reopened as a non-inline
namespace}}
+namespace X {} // expected-warning {{inline namespace reopened as a non-inline
namespace}}
Index: clang/test/Parser/cxx2a-inline-nested-namespace-definition.cpp
===================================================================
--- clang/test/Parser/cxx2a-inline-nested-namespace-definition.cpp
+++ clang/test/Parser/cxx2a-inline-nested-namespace-definition.cpp
@@ -17,7 +17,7 @@
// expected-warning@+2 {{inline nested namespace definition is incompatible
with C++ standards before C++20}}
#endif
namespace valid1::valid2::inline valid3::inline valid4::valid5 {}
-// expected-note@-1 2 {{previous definition is here}}
+// expected-note@-1 4 {{previous definition is here}}
#if __cplusplus <= 201402L
// expected-warning@+3 {{nested namespace definition is a C++17 extension;
define each namespace separately}}
@@ -34,7 +34,6 @@
// expected-warning@+2 {{inline nested namespace definition is incompatible
with C++ standards before C++20}}
#endif
namespace valid1::valid2::inline valid3::inline valid4::valid5 {}
-// expected-note@-1 2 {{previous definition is here}}
namespace valid1 {
namespace valid2 {
Index: clang/lib/Sema/SemaDeclCXX.cpp
===================================================================
--- clang/lib/Sema/SemaDeclCXX.cpp
+++ clang/lib/Sema/SemaDeclCXX.cpp
@@ -11059,6 +11059,12 @@
NamespaceDecl *PrevNS) {
assert(*IsInline != PrevNS->isInline());
+ if (auto *FirstNS = PrevNS->getFirstDecl())
+ // 'inline' must appear on the original definition, but not necessarily
+ // on all extension definitions, so the note should point to the first
+ // definition to avoid confusion.
+ PrevNS = FirstNS;
+
if (PrevNS->isInline())
// The user probably just forgot the 'inline', so suggest that it
// be added back.
Index: clang/test/SemaCXX/warn-inline-namespace-reopened-twice.cpp
===================================================================
--- /dev/null
+++ clang/test/SemaCXX/warn-inline-namespace-reopened-twice.cpp
@@ -0,0 +1,9 @@
+// RUN: %clang_cc1 -fsyntax-only -Wall -verify -std=c++11 %s
+
+// Regression test for #50794.
+
+// expected-note@+1 2 {{previous definition is here}}
+inline namespace X {}
+
+namespace X {} // expected-warning {{inline namespace reopened as a non-inline namespace}}
+namespace X {} // expected-warning {{inline namespace reopened as a non-inline namespace}}
Index: clang/test/Parser/cxx2a-inline-nested-namespace-definition.cpp
===================================================================
--- clang/test/Parser/cxx2a-inline-nested-namespace-definition.cpp
+++ clang/test/Parser/cxx2a-inline-nested-namespace-definition.cpp
@@ -17,7 +17,7 @@
// expected-warning@+2 {{inline nested namespace definition is incompatible with C++ standards before C++20}}
#endif
namespace valid1::valid2::inline valid3::inline valid4::valid5 {}
-// expected-note@-1 2 {{previous definition is here}}
+// expected-note@-1 4 {{previous definition is here}}
#if __cplusplus <= 201402L
// expected-warning@+3 {{nested namespace definition is a C++17 extension; define each namespace separately}}
@@ -34,7 +34,6 @@
// expected-warning@+2 {{inline nested namespace definition is incompatible with C++ standards before C++20}}
#endif
namespace valid1::valid2::inline valid3::inline valid4::valid5 {}
-// expected-note@-1 2 {{previous definition is here}}
namespace valid1 {
namespace valid2 {
Index: clang/lib/Sema/SemaDeclCXX.cpp
===================================================================
--- clang/lib/Sema/SemaDeclCXX.cpp
+++ clang/lib/Sema/SemaDeclCXX.cpp
@@ -11059,6 +11059,12 @@
NamespaceDecl *PrevNS) {
assert(*IsInline != PrevNS->isInline());
+ if (auto *FirstNS = PrevNS->getFirstDecl())
+ // 'inline' must appear on the original definition, but not necessarily
+ // on all extension definitions, so the note should point to the first
+ // definition to avoid confusion.
+ PrevNS = FirstNS;
+
if (PrevNS->isInline())
// The user probably just forgot the 'inline', so suggest that it
// be added back.
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