https://github.com/riyaz86a updated https://github.com/llvm/llvm-project/pull/176551
>From d1f68b116134570b1c826f9532a2a7ddf1e9b348 Mon Sep 17 00:00:00 2001 From: Riyaz Ahmad <[email protected]> Date: Sat, 17 Jan 2026 04:16:28 -0500 Subject: [PATCH] [Frontend][Sema] Add CC1-only -fms-anonymous-structs to enable Microsoft anonymous struct/union feature Add a CC1-only option `-fms-anonymous-structs` to enable Microsoft anonymous struct/union feature without enabling full Microsoft extensions. Motivation: - On AIX, some Microsoft extensions (e.g _ptr32) conflict with system headers. - Certain code bases rely on Microsoft anonymous structs/unions behavior. This new option allows selectively enabling the anonymous struct/union features in the front-end without triggering other Microsoft extensions features. CC1 option can be passed via clang "-Xclang -fms-anonymous-structs". Implementation: - Introduced CC1-only option `-fms-anonymous-structs`. - The option updates LangOpts::MSAnonymousStructs and Updated Sema to use this flag. - Added frontend, driver, and Sema tests. --- clang/include/clang/Basic/LangOptions.def | 1 + clang/include/clang/Options/Options.td | 5 ++ clang/lib/Driver/ToolChains/Clang.cpp | 4 +- clang/lib/Sema/SemaDecl.cpp | 3 +- clang/test/Driver/cl-options.c | 3 + clang/test/Driver/unknown-arg.c | 2 + clang/test/Frontend/ms-anon-structs-args.c | 15 ++++ clang/test/Sema/MicrosoftAnonymousStructs.c | 81 +++++++++++++++++++ .../Frontend/CompilerInvocationTest.cpp | 24 ++++++ 9 files changed, 136 insertions(+), 2 deletions(-) create mode 100644 clang/test/Frontend/ms-anon-structs-args.c create mode 100644 clang/test/Sema/MicrosoftAnonymousStructs.c diff --git a/clang/include/clang/Basic/LangOptions.def b/clang/include/clang/Basic/LangOptions.def index 36fec24638363..4420cd942cac0 100644 --- a/clang/include/clang/Basic/LangOptions.def +++ b/clang/include/clang/Basic/LangOptions.def @@ -47,6 +47,7 @@ LANGOPT(MSVCCompat , 1, 0, NotCompatible, "Microsoft Visual C++ full comp LANGOPT(Kernel , 1, 0, NotCompatible, "Kernel mode") LANGOPT(MicrosoftExt , 1, 0, NotCompatible, "Microsoft C++ extensions") LANGOPT(ZOSExt , 1, 0, NotCompatible, "z/OS extensions") +LANGOPT(MSAnonymousStructs, 1, 0, NotCompatible, "Microsoft anonymous struct and union extension") LANGOPT(AsmBlocks , 1, 0, NotCompatible, "Microsoft inline asm blocks") LANGOPT(Borland , 1, 0, NotCompatible, "Borland extensions") LANGOPT(CPlusPlus , 1, 0, NotCompatible, "C++") diff --git a/clang/include/clang/Options/Options.td b/clang/include/clang/Options/Options.td index 188739e72434a..f6d128a4dd916 100644 --- a/clang/include/clang/Options/Options.td +++ b/clang/include/clang/Options/Options.td @@ -3327,6 +3327,11 @@ def fms_extensions : Flag<["-"], "fms-extensions">, Group<f_Group>, Visibility<[ClangOption, CC1Option, CLOption]>, HelpText<"Accept some non-standard constructs supported by the Microsoft compiler">, MarshallingInfoFlag<LangOpts<"MicrosoftExt">>, ImpliedByAnyOf<[fms_compatibility.KeyPath]>; +def fms_anonymous_structs + : Flag<["-"], "fms-anonymous-structs">, + Visibility<[CC1Option]>, + HelpText<"Enable Microsoft anonymous struct/union extension.">, + MarshallingInfoFlag<LangOpts<"MSAnonymousStructs">>; defm asm_blocks : BoolFOption<"asm-blocks", LangOpts<"AsmBlocks">, Default<fms_extensions.KeyPath>, PosFlag<SetTrue, [], [ClangOption, CC1Option]>, diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp index 41ee88fd5501a..b0fd41e0a026e 100644 --- a/clang/lib/Driver/ToolChains/Clang.cpp +++ b/clang/lib/Driver/ToolChains/Clang.cpp @@ -7156,8 +7156,10 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA, // -fms-extensions=0 is default. if (Args.hasFlag(options::OPT_fms_extensions, options::OPT_fno_ms_extensions, - IsWindowsMSVC || IsUEFI)) + IsWindowsMSVC || IsUEFI)) { CmdArgs.push_back("-fms-extensions"); + CmdArgs.push_back("-fms-anonymous-structs"); + } // -fms-compatibility=0 is default. bool IsMSVCCompat = Args.hasFlag( diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp index ae779d6830d9b..c2359c6c549d0 100644 --- a/clang/lib/Sema/SemaDecl.cpp +++ b/clang/lib/Sema/SemaDecl.cpp @@ -5342,7 +5342,8 @@ Decl *Sema::ParsedFreeStandingDeclSpec(Scope *S, AccessSpecifier AS, DS.getTypeSpecType() == DeclSpec::TST_typename) { RecordDecl *Record = Tag ? dyn_cast<RecordDecl>(Tag) : DS.getRepAsType().get()->getAsRecordDecl(); - if (Record && getLangOpts().MicrosoftExt) { + if ((Record && getLangOpts().MicrosoftExt) || + (Record && getLangOpts().MSAnonymousStructs)) { Diag(DS.getBeginLoc(), diag::ext_ms_anonymous_record) << Record->isUnion() << DS.getSourceRange(); return BuildMicrosoftCAnonymousStruct(S, DS, Record); diff --git a/clang/test/Driver/cl-options.c b/clang/test/Driver/cl-options.c index 611d0d2927c43..f4ee39d3fc7d9 100644 --- a/clang/test/Driver/cl-options.c +++ b/clang/test/Driver/cl-options.c @@ -350,6 +350,9 @@ // WJoined: "-cc1" // WJoined: "-Wunused-pragmas" +// RUN: %clang_cl -c -fms-extensions -### -- %s 2>&1 | FileCheck -check-prefix=CHECK-MS-ANON-STRUCT %s +// CHECK-MS-ANON-STRUCT: "-fms-extensions" "-fms-anonymous-structs" + // We recognize -f[no-]strict-aliasing. // RUN: %clang_cl -c -### -- %s 2>&1 | FileCheck -check-prefix=DEFAULTSTRICT %s // DEFAULTSTRICT: "-relaxed-aliasing" diff --git a/clang/test/Driver/unknown-arg.c b/clang/test/Driver/unknown-arg.c index 26032a407f413..b209b1bff0c9f 100644 --- a/clang/test/Driver/unknown-arg.c +++ b/clang/test/Driver/unknown-arg.c @@ -25,6 +25,7 @@ // This needs to exit non-0, for configure scripts. // RUN: not %clang /GR- +// RUN: not %clang %s -fms-anonymous-structs -### 2>&1 | FileCheck %s --check-prefix=CL-MS-ERROR // CHECK: error: unknown argument: '-cake-is-lie' // CHECK: error: unknown argument: '-%0' @@ -70,3 +71,4 @@ // O-WARN: warning: joined argument treated as '-o ffload-arch=sm_70'; did you mean '--offload-arch=sm_70'? // O-WARN-NEXT: warning: joined argument treated as '-o ffload-device-only'; did you mean '--offload-device-only'? // O-WARN-NEXT: warning: joined argument treated as '-o utput'; did you mean '--output'? +// CL-MS-ERROR: error: unknown argument '-fms-anonymous-structs'; did you mean '-Xclang -fms-anonymous-structs'? diff --git a/clang/test/Frontend/ms-anon-structs-args.c b/clang/test/Frontend/ms-anon-structs-args.c new file mode 100644 index 0000000000000..ddd3cea598959 --- /dev/null +++ b/clang/test/Frontend/ms-anon-structs-args.c @@ -0,0 +1,15 @@ +// Test that -fms-anonymous-structs is a CC1-only option and properly rejected by driver + +// RUN: %clang_cc1 -triple powerpc-ibm-aix -fms-anonymous-structs %s -fsyntax-only 2>&1 | \ +// RUN: FileCheck --check-prefix=CC1-OK %s --allow-empty +// CC1-OK-NOT: error: unknown argument + +// Test that multiple occurrences are handled +// RUN: %clang_cc1 -triple powerpc-ibm-aix -fms-anonymous-structs -fms-anonymous-structs %s -fsyntax-only 2>&1 | \ +// RUN: FileCheck --check-prefix=MULTI-OK %s --allow-empty +// MULTI-OK-NOT: error: unknown argument + +// Test with other MS-related options +// RUN: %clang_cc1 -triple powerpc-ibm-aix -fms-extensions -fms-anonymous-structs %s -fsyntax-only 2>&1 | \ +// RUN: FileCheck --check-prefix=WITH-MS-EXT %s --allow-empty +// WITH-MS-EXT-NOT: error: unknown argument diff --git a/clang/test/Sema/MicrosoftAnonymousStructs.c b/clang/test/Sema/MicrosoftAnonymousStructs.c new file mode 100644 index 0000000000000..163c2f726cb67 --- /dev/null +++ b/clang/test/Sema/MicrosoftAnonymousStructs.c @@ -0,0 +1,81 @@ +// RUN: %clang_cc1 -triple i686-windows %s -fsyntax-only -Wno-unused-value -Wno-pointer-to-int-cast -Wmicrosoft -verify -fms-anonymous-structs +// RUN: %clang_cc1 -triple powerpc-ibm-aix %s -fsyntax-only -Wno-unused-value -Wno-pointer-to-int-cast -Wmicrosoft -verify -fms-anonymous-structs + +typedef struct notnested { + long bad1; + long bad2; +} NOTNESTED; + + +typedef struct nested1 { + long a; + struct notnested var1; + NOTNESTED var2; +} NESTED1; + +struct nested2 { + long b; + NESTED1; // expected-warning {{anonymous structs are a Microsoft extension}} +}; + +struct nested2 PR20573 = { .a = 3 }; + +struct nested3 { + long d; + struct nested4 { // expected-warning {{anonymous structs are a Microsoft extension}} + long e; + }; + union nested5 { // expected-warning {{anonymous unions are a Microsoft extension}} + long f; + }; +}; + +typedef union nested6 { + long f; +} NESTED6; + +struct test { + int c; + struct nested2; // expected-warning {{anonymous structs are a Microsoft extension}} + NESTED6; // expected-warning {{anonymous unions are a Microsoft extension}} +}; + +void foo(void) +{ + struct test var; + var.a; + var.b; + var.c; + var.bad1; // expected-error {{no member named 'bad1' in 'struct test'}} + var.bad2; // expected-error {{no member named 'bad2' in 'struct test'}} +} + +// Enumeration types with a fixed underlying type. +const int seventeen = 17; +typedef int Int; + +void pointer_to_integral_type_conv(char* ptr) { + char ch = (char)ptr; + short sh = (short)ptr; + ch = (char)ptr; + sh = (short)ptr; + + // This is valid ISO C. + _Bool b = (_Bool)ptr; +} + +typedef struct { + UNKNOWN u; // expected-error {{unknown type name 'UNKNOWN'}} +} AA; + +typedef struct { + AA; // expected-warning {{anonymous structs are a Microsoft extension}} +} BB; + +struct anon_fault { + struct undefined; // expected-warning {{anonymous structs are a Microsoft extension}} + // expected-error@-1 {{field has incomplete type 'struct undefined'}} + // expected-note@-2 {{forward declaration of 'struct undefined'}} +}; + +const int anon_falt_size = sizeof(struct anon_fault); diff --git a/clang/unittests/Frontend/CompilerInvocationTest.cpp b/clang/unittests/Frontend/CompilerInvocationTest.cpp index 64d0f4c38f11c..a9d5b57d3bc3f 100644 --- a/clang/unittests/Frontend/CompilerInvocationTest.cpp +++ b/clang/unittests/Frontend/CompilerInvocationTest.cpp @@ -190,6 +190,30 @@ TEST_F(CommandLineTest, BoolOptionDefaultTrueSingleFlagPresent) { ASSERT_THAT(GeneratedArgs, Contains(StrEq("-fno-temp-file"))); } +TEST_F(CommandLineTest, MSAnonymousStructsFlagPresent) { + const char *Args[] = {"-cc1", "-fms-anonymous-structs"}; + + ASSERT_TRUE(CompilerInvocation::CreateFromArgs(Invocation, Args, *Diags)); + + EXPECT_TRUE(Invocation.getLangOpts().MSAnonymousStructs); + + Invocation.generateCC1CommandLine(GeneratedArgs, *this); + + ASSERT_THAT(GeneratedArgs, Contains(StrEq("-fms-anonymous-structs"))); +} + +TEST_F(CommandLineTest, MSAnonymousStructsEnabledByMSExtensions) { + const char *Args[] = {"clang", "-fms-extensions"}; + + ASSERT_TRUE(CompilerInvocation::CreateFromArgs(Invocation, Args, *Diags)); + + EXPECT_TRUE(Invocation.getLangOpts().MSAnonymousStructs); + + Invocation.generateCC1CommandLine(GeneratedArgs, *this); + + ASSERT_THAT(GeneratedArgs, Contains(StrEq("-fms-anonymous-structs"))); +} + TEST_F(CommandLineTest, CC1FlagPresentWhenDoingRoundTrip) { const char *Args[] = {"-cc1", "-round-trip-args"}; _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
