https://github.com/riyaz86a updated https://github.com/llvm/llvm-project/pull/176551
>From 9c01511289217c605e37ca08ee4ccc554d8a9270 Mon Sep 17 00:00:00 2001 From: Riyaz Ahmad <[email protected]> Date: Sat, 17 Jan 2026 04:16:28 -0500 Subject: [PATCH 01/15] [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 | 6 ++ clang/lib/Driver/ToolChains/Clang.cpp | 4 +- clang/lib/Sema/SemaDecl.cpp | 2 +- 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 | 20 +++++ 9 files changed, 132 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..5cdca7132e779 100644 --- a/clang/include/clang/Options/Options.td +++ b/clang/include/clang/Options/Options.td @@ -3327,6 +3327,12 @@ 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]>, + MarshallingInfoFlag<LangOpts<"MSAnonymousStructs">>, + ImpliedByAnyOf<[fms_extensions.KeyPath]>, + HelpText<"Enable Microsoft anonymous struct/union extension.">; 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..4f030c6ec649f 100644 --- a/clang/lib/Sema/SemaDecl.cpp +++ b/clang/lib/Sema/SemaDecl.cpp @@ -5342,7 +5342,7 @@ 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().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..cf758c4ae2c50 100644 --- a/clang/unittests/Frontend/CompilerInvocationTest.cpp +++ b/clang/unittests/Frontend/CompilerInvocationTest.cpp @@ -190,6 +190,26 @@ 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); +} + TEST_F(CommandLineTest, CC1FlagPresentWhenDoingRoundTrip) { const char *Args[] = {"-cc1", "-round-trip-args"}; >From d503955da34dc705678fc1cae8c4a8400c990c6a Mon Sep 17 00:00:00 2001 From: Riyaz Ahmad <[email protected]> Date: Wed, 21 Jan 2026 12:17:55 -0500 Subject: [PATCH 02/15] [Frontend][Sema] Address review comments --- clang/lib/Driver/ToolChains/Clang.cpp | 1 - clang/test/Driver/unknown-arg.c | 2 -- clang/test/Sema/MicrosoftAnonymousStructs.c | 1 + .../Frontend/CompilerInvocationTest.cpp | 20 ------------------- 4 files changed, 1 insertion(+), 23 deletions(-) diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp index b0fd41e0a026e..de4dc62497433 100644 --- a/clang/lib/Driver/ToolChains/Clang.cpp +++ b/clang/lib/Driver/ToolChains/Clang.cpp @@ -7158,7 +7158,6 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA, if (Args.hasFlag(options::OPT_fms_extensions, options::OPT_fno_ms_extensions, IsWindowsMSVC || IsUEFI)) { CmdArgs.push_back("-fms-extensions"); - CmdArgs.push_back("-fms-anonymous-structs"); } // -fms-compatibility=0 is default. diff --git a/clang/test/Driver/unknown-arg.c b/clang/test/Driver/unknown-arg.c index b209b1bff0c9f..26032a407f413 100644 --- a/clang/test/Driver/unknown-arg.c +++ b/clang/test/Driver/unknown-arg.c @@ -25,7 +25,6 @@ // 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' @@ -71,4 +70,3 @@ // 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/Sema/MicrosoftAnonymousStructs.c b/clang/test/Sema/MicrosoftAnonymousStructs.c index 163c2f726cb67..3f81962515d4d 100644 --- a/clang/test/Sema/MicrosoftAnonymousStructs.c +++ b/clang/test/Sema/MicrosoftAnonymousStructs.c @@ -1,5 +1,6 @@ // 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 +// RUN: %clang_cc1 -triple i686-windows %s -fsyntax-only -Wno-unused-value -Wno-pointer-to-int-cast -Wmicrosoft -verify -fms-extensions typedef struct notnested { long bad1; diff --git a/clang/unittests/Frontend/CompilerInvocationTest.cpp b/clang/unittests/Frontend/CompilerInvocationTest.cpp index cf758c4ae2c50..64d0f4c38f11c 100644 --- a/clang/unittests/Frontend/CompilerInvocationTest.cpp +++ b/clang/unittests/Frontend/CompilerInvocationTest.cpp @@ -190,26 +190,6 @@ 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); -} - TEST_F(CommandLineTest, CC1FlagPresentWhenDoingRoundTrip) { const char *Args[] = {"-cc1", "-round-trip-args"}; >From 4ea10266307d37d7782b336db3c043ec8b5ff175 Mon Sep 17 00:00:00 2001 From: Riyaz Ahmad <[email protected]> Date: Wed, 21 Jan 2026 14:15:13 -0500 Subject: [PATCH 03/15] [Frontend][Sema] Address review comments. --- clang/include/clang/Options/Options.td | 2 +- clang/lib/Driver/ToolChains/Clang.cpp | 3 +- clang/test/Driver/cl-options.c | 3 -- clang/test/Frontend/ms-anon-structs-args.c | 7 ++- clang/test/Sema/MicrosoftAnonymousStructs.c | 53 ++++++++++++++------- 5 files changed, 43 insertions(+), 25 deletions(-) diff --git a/clang/include/clang/Options/Options.td b/clang/include/clang/Options/Options.td index 5cdca7132e779..1b959826daade 100644 --- a/clang/include/clang/Options/Options.td +++ b/clang/include/clang/Options/Options.td @@ -3331,7 +3331,7 @@ def fms_anonymous_structs : Flag<["-"], "fms-anonymous-structs">, Visibility<[CC1Option]>, MarshallingInfoFlag<LangOpts<"MSAnonymousStructs">>, - ImpliedByAnyOf<[fms_extensions.KeyPath]>, + ImpliedByAnyOf<[fms_extensions.KeyPath, fms_compatibility.KeyPath]>, HelpText<"Enable Microsoft anonymous struct/union extension.">; defm asm_blocks : BoolFOption<"asm-blocks", LangOpts<"AsmBlocks">, Default<fms_extensions.KeyPath>, diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp index de4dc62497433..41ee88fd5501a 100644 --- a/clang/lib/Driver/ToolChains/Clang.cpp +++ b/clang/lib/Driver/ToolChains/Clang.cpp @@ -7156,9 +7156,8 @@ 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"); - } // -fms-compatibility=0 is default. bool IsMSVCCompat = Args.hasFlag( diff --git a/clang/test/Driver/cl-options.c b/clang/test/Driver/cl-options.c index f4ee39d3fc7d9..611d0d2927c43 100644 --- a/clang/test/Driver/cl-options.c +++ b/clang/test/Driver/cl-options.c @@ -350,9 +350,6 @@ // 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/Frontend/ms-anon-structs-args.c b/clang/test/Frontend/ms-anon-structs-args.c index ddd3cea598959..e2f6edeef20c1 100644 --- a/clang/test/Frontend/ms-anon-structs-args.c +++ b/clang/test/Frontend/ms-anon-structs-args.c @@ -1,4 +1,4 @@ -// Test that -fms-anonymous-structs is a CC1-only option and properly rejected by driver +// Test that -fms-anonymous-structs is a CC1-only option and is accepted by CC1 without error. // RUN: %clang_cc1 -triple powerpc-ibm-aix -fms-anonymous-structs %s -fsyntax-only 2>&1 | \ // RUN: FileCheck --check-prefix=CC1-OK %s --allow-empty @@ -13,3 +13,8 @@ // 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 + +// Test rejection of the unsupported negative form. +// RUN: not %clang_cc1 -triple powerpc-ibm-aix -fno-ms-anonymous-structs %s -fsyntax-only 2>&1 | \ +// RUN: FileCheck %s +// CHECK: error: unknown argument: '-fno-ms-anonymous-structs' diff --git a/clang/test/Sema/MicrosoftAnonymousStructs.c b/clang/test/Sema/MicrosoftAnonymousStructs.c index 3f81962515d4d..cf47322f59df7 100644 --- a/clang/test/Sema/MicrosoftAnonymousStructs.c +++ b/clang/test/Sema/MicrosoftAnonymousStructs.c @@ -1,6 +1,13 @@ -// 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 -// RUN: %clang_cc1 -triple i686-windows %s -fsyntax-only -Wno-unused-value -Wno-pointer-to-int-cast -Wmicrosoft -verify -fms-extensions +// RUN: %clang_cc1 -triple i686-windows %s -fsyntax-only -Wno-unused-value \ +// RUN: -Wno-pointer-to-int-cast -Wmicrosoft -verify=ms-anonymous -fms-anonymous-structs +// RUN: %clang_cc1 -triple powerpc-ibm-aix %s -fsyntax-only -Wno-unused-value \ +// RUN: -Wno-pointer-to-int-cast -Wmicrosoft -verify=ms-anonymous -fms-anonymous-structs +// RUN: %clang_cc1 -triple i686-windows %s -fsyntax-only -Wno-unused-value \ +// RUN: -Wno-pointer-to-int-cast -Wmicrosoft -verify=ms-anonymous -fms-extensions +// RUN: %clang_cc1 -triple i686-windows %s -fsyntax-only -Wno-unused-value \ +// RUN: -Wno-pointer-to-int-cast -Wmicrosoft -verify=ms-anonymous -fms-compatibility +// RUN: %clang_cc1 -triple i686-windows %s -fsyntax-only -Wno-unused-value \ +// RUN: -Wno-pointer-to-int-cast -Wmicrosoft -verify=ms-anonymous-dis typedef struct notnested { long bad1; @@ -16,17 +23,20 @@ typedef struct nested1 { struct nested2 { long b; - NESTED1; // expected-warning {{anonymous structs are a Microsoft extension}} + NESTED1; // ms-anonymous-warning {{anonymous structs are a Microsoft extension}} + // ms-anonymous-dis-warning@-1 {{declaration does not declare anything}} }; -struct nested2 PR20573 = { .a = 3 }; +struct nested2 PR20573 = { .a = 3 }; // ms-anonymous-dis-error {{field designator 'a' does not refer to any field in type 'struct nested2'}} struct nested3 { long d; - struct nested4 { // expected-warning {{anonymous structs are a Microsoft extension}} + struct nested4 { // ms-anonymous-warning {{anonymous structs are a Microsoft extension}} + // ms-anonymous-dis-warning@-1 {{declaration does not declare anything}} long e; }; - union nested5 { // expected-warning {{anonymous unions are a Microsoft extension}} + union nested5 { // ms-anonymous-warning {{anonymous unions are a Microsoft extension}} + // ms-anonymous-dis-warning@-1 {{declaration does not declare anything}} long f; }; }; @@ -37,18 +47,22 @@ typedef union nested6 { struct test { int c; - struct nested2; // expected-warning {{anonymous structs are a Microsoft extension}} - NESTED6; // expected-warning {{anonymous unions are a Microsoft extension}} + struct nested2; // ms-anonymous-warning {{anonymous structs are a Microsoft extension}} + // ms-anonymous-dis-warning@-1 {{declaration does not declare anything}} + NESTED6; // ms-anonymous-warning {{anonymous unions are a Microsoft extension}} + // ms-anonymous-dis-warning@-1 {{declaration does not declare anything}} }; void foo(void) { struct test var; - var.a; - var.b; + var.a; // ms-anonymous-dis-error {{no member named 'a' in 'struct test'}} + var.b; // ms-anonymous-dis-error {{no member named 'b' in 'struct test'}} var.c; - var.bad1; // expected-error {{no member named 'bad1' in 'struct test'}} - var.bad2; // expected-error {{no member named 'bad2' in 'struct test'}} + var.bad1; // ms-anonymous-error {{no member named 'bad1' in 'struct test'}} + // ms-anonymous-dis-error@-1 {{no member named 'bad1' in 'struct test'}} + var.bad2; // ms-anonymous-error {{no member named 'bad2' in 'struct test'}} + // ms-anonymous-dis-error@-1 {{no member named 'bad2' in 'struct test'}} } // Enumeration types with a fixed underlying type. @@ -66,17 +80,20 @@ void pointer_to_integral_type_conv(char* ptr) { } typedef struct { - UNKNOWN u; // expected-error {{unknown type name 'UNKNOWN'}} + UNKNOWN u; // ms-anonymous-error {{unknown type name 'UNKNOWN'}} + // ms-anonymous-dis-error@-1 {{unknown type name 'UNKNOWN'}} } AA; typedef struct { - AA; // expected-warning {{anonymous structs are a Microsoft extension}} + AA; // ms-anonymous-warning {{anonymous structs are a Microsoft extension}} + // ms-anonymous-dis-warning@-1 {{declaration does not declare anything}} } 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'}} + struct undefined; // ms-anonymous-warning {{anonymous structs are a Microsoft extension}} + // ms-anonymous-error@-1 {{field has incomplete type 'struct undefined'}} + // ms-anonymous-note@-2 {{forward declaration of 'struct undefined'}} + // ms-anonymous-dis-warning@-3 {{declaration does not declare anything}} }; const int anon_falt_size = sizeof(struct anon_fault); >From e3fb3bd01360b5ab3ba4babdc9295256f34b3918 Mon Sep 17 00:00:00 2001 From: Riyaz Ahmad <[email protected]> Date: Thu, 22 Jan 2026 02:43:18 -0500 Subject: [PATCH 04/15] [Frontend][Sema] Address review comments. --- clang/test/Sema/MicrosoftAnonymousStructs.c | 76 ++++----------------- 1 file changed, 15 insertions(+), 61 deletions(-) diff --git a/clang/test/Sema/MicrosoftAnonymousStructs.c b/clang/test/Sema/MicrosoftAnonymousStructs.c index cf47322f59df7..d0b32ce53a3ff 100644 --- a/clang/test/Sema/MicrosoftAnonymousStructs.c +++ b/clang/test/Sema/MicrosoftAnonymousStructs.c @@ -11,89 +11,43 @@ typedef struct notnested { long bad1; - long bad2; } NOTNESTED; - typedef struct nested1 { long a; - struct notnested var1; NOTNESTED var2; } NESTED1; struct nested2 { long b; - NESTED1; // ms-anonymous-warning {{anonymous structs are a Microsoft extension}} - // ms-anonymous-dis-warning@-1 {{declaration does not declare anything}} -}; - -struct nested2 PR20573 = { .a = 3 }; // ms-anonymous-dis-error {{field designator 'a' does not refer to any field in type 'struct nested2'}} - -struct nested3 { - long d; - struct nested4 { // ms-anonymous-warning {{anonymous structs are a Microsoft extension}} + NESTED1; // ms-anonymous-warning {{anonymous structs are a Microsoft extension}} // ms-anonymous-dis-warning@-1 {{declaration does not declare anything}} - long e; - }; - union nested5 { // ms-anonymous-warning {{anonymous unions are a Microsoft extension}} - // ms-anonymous-dis-warning@-1 {{declaration does not declare anything}} - long f; - }; }; -typedef union nested6 { +typedef union nested3 { long f; -} NESTED6; +} NESTED3; struct test { int c; struct nested2; // ms-anonymous-warning {{anonymous structs are a Microsoft extension}} // ms-anonymous-dis-warning@-1 {{declaration does not declare anything}} - NESTED6; // ms-anonymous-warning {{anonymous unions are a Microsoft extension}} - // ms-anonymous-dis-warning@-1 {{declaration does not declare anything}} + NESTED3; // ms-anonymous-warning {{anonymous unions are a Microsoft extension}} + // ms-anonymous-dis-warning@-1 {{declaration does not declare anything}} +}; + +struct nested4 { + long d; + struct nested5 { // ms-anonymous-warning {{anonymous structs are a Microsoft extension}} + // ms-anonymous-dis-warning@-1 {{declaration does not declare anything}} + long e; + }; }; void foo(void) { struct test var; - var.a; // ms-anonymous-dis-error {{no member named 'a' in 'struct test'}} - var.b; // ms-anonymous-dis-error {{no member named 'b' in 'struct test'}} var.c; - var.bad1; // ms-anonymous-error {{no member named 'bad1' in 'struct test'}} - // ms-anonymous-dis-error@-1 {{no member named 'bad1' in 'struct test'}} - var.bad2; // ms-anonymous-error {{no member named 'bad2' in 'struct test'}} - // ms-anonymous-dis-error@-1 {{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; + var.b; // ms-anonymous-dis-error {{no member named 'b' in 'struct test'}} + var.f; // ms-anonymous-dis-error {{no member named 'f' in 'struct test'}} } - -typedef struct { - UNKNOWN u; // ms-anonymous-error {{unknown type name 'UNKNOWN'}} - // ms-anonymous-dis-error@-1 {{unknown type name 'UNKNOWN'}} -} AA; - -typedef struct { - AA; // ms-anonymous-warning {{anonymous structs are a Microsoft extension}} - // ms-anonymous-dis-warning@-1 {{declaration does not declare anything}} -} BB; - -struct anon_fault { - struct undefined; // ms-anonymous-warning {{anonymous structs are a Microsoft extension}} - // ms-anonymous-error@-1 {{field has incomplete type 'struct undefined'}} - // ms-anonymous-note@-2 {{forward declaration of 'struct undefined'}} - // ms-anonymous-dis-warning@-3 {{declaration does not declare anything}} -}; - -const int anon_falt_size = sizeof(struct anon_fault); >From 368d435724608fee9655faa660c803111b2054f9 Mon Sep 17 00:00:00 2001 From: Riyaz Ahmad <[email protected]> Date: Fri, 23 Jan 2026 01:03:05 -0500 Subject: [PATCH 05/15] [Frontend][Sema] Address review comments. --- clang/test/Sema/MicrosoftAnonymousStructs.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/clang/test/Sema/MicrosoftAnonymousStructs.c b/clang/test/Sema/MicrosoftAnonymousStructs.c index d0b32ce53a3ff..f9b6fa20c5bd1 100644 --- a/clang/test/Sema/MicrosoftAnonymousStructs.c +++ b/clang/test/Sema/MicrosoftAnonymousStructs.c @@ -9,13 +9,12 @@ // RUN: %clang_cc1 -triple i686-windows %s -fsyntax-only -Wno-unused-value \ // RUN: -Wno-pointer-to-int-cast -Wmicrosoft -verify=ms-anonymous-dis -typedef struct notnested { - long bad1; -} NOTNESTED; +struct union_mem { + long g; +}; typedef struct nested1 { long a; - NOTNESTED var2; } NESTED1; struct nested2 { @@ -26,6 +25,8 @@ struct nested2 { typedef union nested3 { long f; + struct union_mem; // ms-anonymous-warning {{anonymous structs are a Microsoft extension}} + // ms-anonymous-dis-warning@-1 {{declaration does not declare anything}} } NESTED3; struct test { @@ -48,6 +49,8 @@ void foo(void) { struct test var; var.c; + var.a; // ms-anonymous-dis-error {{no member named 'a' in 'struct test'}} var.b; // ms-anonymous-dis-error {{no member named 'b' in 'struct test'}} var.f; // ms-anonymous-dis-error {{no member named 'f' in 'struct test'}} + var.g; // ms-anonymous-dis-error {{no member named 'g' in 'struct test'}} } >From 6bda77381fa52674a13dee70e6640818119112d8 Mon Sep 17 00:00:00 2001 From: Riyaz Ahmad <[email protected]> Date: Fri, 23 Jan 2026 11:12:55 -0500 Subject: [PATCH 06/15] [Clang] Add release notes for -fms-anonymous-structs CC1 option --- clang/docs/ReleaseNotes.rst | 1 + 1 file changed, 1 insertion(+) diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index 5fd607d98faa3..b8b2b83b58981 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -109,6 +109,7 @@ Non-comprehensive list of changes in this release New Compiler Flags ------------------ +- New CC1 option ``-fms-anonymous-structs`` added to enable only Microsoft's anonymous struct/union extension without enabling other ``-fms-extensions`` features [GH177607]. Deprecated Compiler Flags ------------------------- >From c3c5543e6905d598332561357a4eafd90776c004 Mon Sep 17 00:00:00 2001 From: Riyaz Ahmad <[email protected]> Date: Sat, 24 Jan 2026 11:43:37 -0500 Subject: [PATCH 07/15] [Frontend][Sema] Address review comments. --- clang/include/clang/Options/Options.td | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/clang/include/clang/Options/Options.td b/clang/include/clang/Options/Options.td index 1b959826daade..5cdca7132e779 100644 --- a/clang/include/clang/Options/Options.td +++ b/clang/include/clang/Options/Options.td @@ -3331,7 +3331,7 @@ def fms_anonymous_structs : Flag<["-"], "fms-anonymous-structs">, Visibility<[CC1Option]>, MarshallingInfoFlag<LangOpts<"MSAnonymousStructs">>, - ImpliedByAnyOf<[fms_extensions.KeyPath, fms_compatibility.KeyPath]>, + ImpliedByAnyOf<[fms_extensions.KeyPath]>, HelpText<"Enable Microsoft anonymous struct/union extension.">; defm asm_blocks : BoolFOption<"asm-blocks", LangOpts<"AsmBlocks">, Default<fms_extensions.KeyPath>, >From 4a3ba57b8edf9858a0e86ae5020f560672b4b685 Mon Sep 17 00:00:00 2001 From: Riyaz Ahmad <[email protected]> Date: Sat, 24 Jan 2026 11:55:38 -0500 Subject: [PATCH 08/15] Frontend][Sema] Address review comments --- clang/test/Frontend/ms-anon-structs-args.c | 6 ++---- clang/test/Sema/MicrosoftAnonymousStructs.c | 10 +++++----- 2 files changed, 7 insertions(+), 9 deletions(-) diff --git a/clang/test/Frontend/ms-anon-structs-args.c b/clang/test/Frontend/ms-anon-structs-args.c index e2f6edeef20c1..48c0d31b6c159 100644 --- a/clang/test/Frontend/ms-anon-structs-args.c +++ b/clang/test/Frontend/ms-anon-structs-args.c @@ -6,13 +6,11 @@ // 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 +// RUN: FileCheck --check-prefix=CC1-OK %s --allow-empty // 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 +// RUN: FileCheck --check-prefix=CC1-OK %s --allow-empty // Test rejection of the unsupported negative form. // RUN: not %clang_cc1 -triple powerpc-ibm-aix -fno-ms-anonymous-structs %s -fsyntax-only 2>&1 | \ diff --git a/clang/test/Sema/MicrosoftAnonymousStructs.c b/clang/test/Sema/MicrosoftAnonymousStructs.c index f9b6fa20c5bd1..31fba67d4a324 100644 --- a/clang/test/Sema/MicrosoftAnonymousStructs.c +++ b/clang/test/Sema/MicrosoftAnonymousStructs.c @@ -1,13 +1,13 @@ // RUN: %clang_cc1 -triple i686-windows %s -fsyntax-only -Wno-unused-value \ -// RUN: -Wno-pointer-to-int-cast -Wmicrosoft -verify=ms-anonymous -fms-anonymous-structs +// RUN: -Wno-pointer-to-int-cast -Wmicrosoft -verify=ms-anonymous -fms-anonymous-structs // RUN: %clang_cc1 -triple powerpc-ibm-aix %s -fsyntax-only -Wno-unused-value \ -// RUN: -Wno-pointer-to-int-cast -Wmicrosoft -verify=ms-anonymous -fms-anonymous-structs +// RUN: -Wno-pointer-to-int-cast -Wmicrosoft -verify=ms-anonymous -fms-anonymous-structs // RUN: %clang_cc1 -triple i686-windows %s -fsyntax-only -Wno-unused-value \ -// RUN: -Wno-pointer-to-int-cast -Wmicrosoft -verify=ms-anonymous -fms-extensions +// RUN: -Wno-pointer-to-int-cast -Wmicrosoft -verify=ms-anonymous -fms-extensions // RUN: %clang_cc1 -triple i686-windows %s -fsyntax-only -Wno-unused-value \ -// RUN: -Wno-pointer-to-int-cast -Wmicrosoft -verify=ms-anonymous -fms-compatibility +// RUN: -Wno-pointer-to-int-cast -Wmicrosoft -verify=ms-anonymous -fms-compatibility // RUN: %clang_cc1 -triple i686-windows %s -fsyntax-only -Wno-unused-value \ -// RUN: -Wno-pointer-to-int-cast -Wmicrosoft -verify=ms-anonymous-dis +// RUN: -Wno-pointer-to-int-cast -Wmicrosoft -verify=ms-anonymous-dis struct union_mem { long g; >From 0ca900d07e2ad7ad787aef569dd8cbbaf165d1f5 Mon Sep 17 00:00:00 2001 From: Riyaz Ahmad <[email protected]> Date: Sun, 25 Jan 2026 11:01:03 -0500 Subject: [PATCH 09/15] [Frontend][Sema] Add -fno-ms-anonymous-structs option to disable anonymous structs This patch adds support for the -fno-ms-anonymous-structs flag to explicitly disable Microsoft's anonymous struct/union extension, even when -fms-anonymous-structs or -fms-extensions or -fms-compatibility is enabled. Update tests to verify both positive and negative flags work correctly and Added tests to ensure explicit disable overrides implicit enablement. --- clang/include/clang/Options/Options.td | 16 ++++++++++------ clang/test/Frontend/ms-anon-structs-args.c | 14 ++++++++++---- clang/test/Sema/MicrosoftAnonymousStructs.c | 19 +++++++++++++++++++ 3 files changed, 39 insertions(+), 10 deletions(-) diff --git a/clang/include/clang/Options/Options.td b/clang/include/clang/Options/Options.td index 5cdca7132e779..dd7a0139484be 100644 --- a/clang/include/clang/Options/Options.td +++ b/clang/include/clang/Options/Options.td @@ -3327,12 +3327,16 @@ 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]>, - MarshallingInfoFlag<LangOpts<"MSAnonymousStructs">>, - ImpliedByAnyOf<[fms_extensions.KeyPath]>, - HelpText<"Enable Microsoft anonymous struct/union extension.">; +defm fms_anonymous_structs + : BoolFOption<"ms-anonymous-structs", + LangOpts<"MSAnonymousStructs">, + DefaultFalse, + PosFlag<SetTrue, [], [CC1Option], + "Enable Microsoft anonymous struct/union extension.", + [fms_extensions.KeyPath]>, + NegFlag<SetFalse, [], [CC1Option], + "Disable Microsoft anonymous struct/union extension.">, + BothFlags<[], [CC1Option], " Microsoft anonymous struct/union extension">>; defm asm_blocks : BoolFOption<"asm-blocks", LangOpts<"AsmBlocks">, Default<fms_extensions.KeyPath>, PosFlag<SetTrue, [], [ClangOption, CC1Option]>, diff --git a/clang/test/Frontend/ms-anon-structs-args.c b/clang/test/Frontend/ms-anon-structs-args.c index 48c0d31b6c159..38546353655a0 100644 --- a/clang/test/Frontend/ms-anon-structs-args.c +++ b/clang/test/Frontend/ms-anon-structs-args.c @@ -12,7 +12,13 @@ // RUN: %clang_cc1 -triple powerpc-ibm-aix -fms-extensions -fms-anonymous-structs %s -fsyntax-only 2>&1 | \ // RUN: FileCheck --check-prefix=CC1-OK %s --allow-empty -// Test rejection of the unsupported negative form. -// RUN: not %clang_cc1 -triple powerpc-ibm-aix -fno-ms-anonymous-structs %s -fsyntax-only 2>&1 | \ -// RUN: FileCheck %s -// CHECK: error: unknown argument: '-fno-ms-anonymous-structs' +// Test that -fno-ms-anonymous-structs is accepted by CC1 without error. +// RUN: %clang_cc1 -triple powerpc-ibm-aix -fno-ms-anonymous-structs %s -fsyntax-only 2>&1 | \ +// RUN: FileCheck --check-prefix=CC1-OK %s --allow-empty + +// Test toggling between enable and disable (last one wins) +// RUN: %clang_cc1 -triple powerpc-ibm-aix -fms-anonymous-structs -fno-ms-anonymous-structs %s -fsyntax-only 2>&1 | \ +// RUN: FileCheck --check-prefix=CC1-OK %s --allow-empty + +// RUN: %clang_cc1 -triple powerpc-ibm-aix -fno-ms-anonymous-structs -fms-anonymous-structs %s -fsyntax-only 2>&1 | \ +// RUN: FileCheck --check-prefix=CC1-OK %s --allow-empty diff --git a/clang/test/Sema/MicrosoftAnonymousStructs.c b/clang/test/Sema/MicrosoftAnonymousStructs.c index 31fba67d4a324..d5296878dbee6 100644 --- a/clang/test/Sema/MicrosoftAnonymousStructs.c +++ b/clang/test/Sema/MicrosoftAnonymousStructs.c @@ -8,6 +8,25 @@ // RUN: -Wno-pointer-to-int-cast -Wmicrosoft -verify=ms-anonymous -fms-compatibility // RUN: %clang_cc1 -triple i686-windows %s -fsyntax-only -Wno-unused-value \ // RUN: -Wno-pointer-to-int-cast -Wmicrosoft -verify=ms-anonymous-dis +// Test that explicit -fno-ms-anonymous-structs does not enable the feature +// RUN: %clang_cc1 -triple i686-windows %s -fsyntax-only -Wno-unused-value \ +// RUN: -Wno-pointer-to-int-cast -Wmicrosoft -verify=ms-anonymous-dis \ +// RUN: -fno-ms-anonymous-structs +// Test that explicit -fno-ms-anonymous-structs overrides -fms-anonymous-structs +// RUN: %clang_cc1 -triple i686-windows %s -fsyntax-only -Wno-unused-value \ +// RUN: -Wno-pointer-to-int-cast -Wmicrosoft -verify=ms-anonymous-dis \ +// RUN: -fms-anonymous-structs -fno-ms-anonymous-structs +// RUN: %clang_cc1 -triple powerpc-ibm-aix %s -fsyntax-only -Wno-unused-value \ +// RUN: -Wno-pointer-to-int-cast -Wmicrosoft -verify=ms-anonymous-dis \ +// RUN: -fms-anonymous-structs -fno-ms-anonymous-structs +// Test that explicit -fno-ms-anonymous-structs overrides -fms-extensions +// RUN: %clang_cc1 -triple i686-windows %s -fsyntax-only -Wno-unused-value \ +// RUN: -Wno-pointer-to-int-cast -Wmicrosoft -verify=ms-anonymous-dis \ +// RUN: -fms-extensions -fno-ms-anonymous-structs +// Test that explicit -fno-ms-anonymous-structs overrides -fms-compatibility +// RUN: %clang_cc1 -triple i686-windows %s -fsyntax-only -Wno-unused-value \ +// RUN: -Wno-pointer-to-int-cast -Wmicrosoft -verify=ms-anonymous-dis \ +// RUN: -fms-compatibility -fno-ms-anonymous-structs struct union_mem { long g; >From a8ff6b3e20c3ea7c74607183cc613b55da4d2580 Mon Sep 17 00:00:00 2001 From: Riyaz Ahmad <[email protected]> Date: Sun, 25 Jan 2026 23:26:39 -0500 Subject: [PATCH 10/15] [Frontend][Sema] Address review comments. --- clang/test/Frontend/ms-anon-structs-args.c | 2 +- clang/test/Sema/MicrosoftAnonymousStructs.c | 17 +++++++++++------ 2 files changed, 12 insertions(+), 7 deletions(-) diff --git a/clang/test/Frontend/ms-anon-structs-args.c b/clang/test/Frontend/ms-anon-structs-args.c index 38546353655a0..571c50d9f3126 100644 --- a/clang/test/Frontend/ms-anon-structs-args.c +++ b/clang/test/Frontend/ms-anon-structs-args.c @@ -16,7 +16,7 @@ // RUN: %clang_cc1 -triple powerpc-ibm-aix -fno-ms-anonymous-structs %s -fsyntax-only 2>&1 | \ // RUN: FileCheck --check-prefix=CC1-OK %s --allow-empty -// Test toggling between enable and disable (last one wins) +// Test both orderings of using both the negative and positive forms. // RUN: %clang_cc1 -triple powerpc-ibm-aix -fms-anonymous-structs -fno-ms-anonymous-structs %s -fsyntax-only 2>&1 | \ // RUN: FileCheck --check-prefix=CC1-OK %s --allow-empty diff --git a/clang/test/Sema/MicrosoftAnonymousStructs.c b/clang/test/Sema/MicrosoftAnonymousStructs.c index d5296878dbee6..f76eedb183636 100644 --- a/clang/test/Sema/MicrosoftAnonymousStructs.c +++ b/clang/test/Sema/MicrosoftAnonymousStructs.c @@ -8,22 +8,27 @@ // RUN: -Wno-pointer-to-int-cast -Wmicrosoft -verify=ms-anonymous -fms-compatibility // RUN: %clang_cc1 -triple i686-windows %s -fsyntax-only -Wno-unused-value \ // RUN: -Wno-pointer-to-int-cast -Wmicrosoft -verify=ms-anonymous-dis -// Test that explicit -fno-ms-anonymous-structs does not enable the feature +// Test that explicit -fno-ms-anonymous-structs does not enable the feature. // RUN: %clang_cc1 -triple i686-windows %s -fsyntax-only -Wno-unused-value \ // RUN: -Wno-pointer-to-int-cast -Wmicrosoft -verify=ms-anonymous-dis \ // RUN: -fno-ms-anonymous-structs -// Test that explicit -fno-ms-anonymous-structs overrides -fms-anonymous-structs +// Test that explicit -fno-ms-anonymous-structs does not enable the feature. // RUN: %clang_cc1 -triple i686-windows %s -fsyntax-only -Wno-unused-value \ // RUN: -Wno-pointer-to-int-cast -Wmicrosoft -verify=ms-anonymous-dis \ -// RUN: -fms-anonymous-structs -fno-ms-anonymous-structs -// RUN: %clang_cc1 -triple powerpc-ibm-aix %s -fsyntax-only -Wno-unused-value \ +// RUN: -fno-ms-anonymous-structs +// Test that explicit -fno-ms-anonymous-structs overrides -earlier fms-anonymous-structs. +// RUN: %clang_cc1 -triple i686-windows %s -fsyntax-only -Wno-unused-value \ // RUN: -Wno-pointer-to-int-cast -Wmicrosoft -verify=ms-anonymous-dis \ // RUN: -fms-anonymous-structs -fno-ms-anonymous-structs -// Test that explicit -fno-ms-anonymous-structs overrides -fms-extensions +// Test that explicit -fms-anonymous-structs overrides earlier -fno-ms-anonymous-structs. +// RUN: %clang_cc1 -triple i686-windows %s -fsyntax-only -Wno-unused-value \ +// RUN: -Wno-pointer-to-int-cast -Wmicrosoft -verify=ms-anonymous \ +// RUN: -fno-ms-anonymous-structs -fms-anonymous-structs +// Test that explicit -fno-ms-anonymous-structs overrides earlier -fms-extensions. // RUN: %clang_cc1 -triple i686-windows %s -fsyntax-only -Wno-unused-value \ // RUN: -Wno-pointer-to-int-cast -Wmicrosoft -verify=ms-anonymous-dis \ // RUN: -fms-extensions -fno-ms-anonymous-structs -// Test that explicit -fno-ms-anonymous-structs overrides -fms-compatibility +// Test that explicit -fno-ms-anonymous-structs overrides earlier -fms-compatibility. // RUN: %clang_cc1 -triple i686-windows %s -fsyntax-only -Wno-unused-value \ // RUN: -Wno-pointer-to-int-cast -Wmicrosoft -verify=ms-anonymous-dis \ // RUN: -fms-compatibility -fno-ms-anonymous-structs >From 6ed5207feffa0e5465dbb7712075e7f8d759af69 Mon Sep 17 00:00:00 2001 From: Riyaz Ahmad <[email protected]> Date: Mon, 26 Jan 2026 05:43:40 -0500 Subject: [PATCH 11/15] [Frontend][Sema] Address review comments. --- clang/test/Sema/MicrosoftAnonymousStructs.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-) diff --git a/clang/test/Sema/MicrosoftAnonymousStructs.c b/clang/test/Sema/MicrosoftAnonymousStructs.c index f76eedb183636..f656411daea3d 100644 --- a/clang/test/Sema/MicrosoftAnonymousStructs.c +++ b/clang/test/Sema/MicrosoftAnonymousStructs.c @@ -12,11 +12,7 @@ // RUN: %clang_cc1 -triple i686-windows %s -fsyntax-only -Wno-unused-value \ // RUN: -Wno-pointer-to-int-cast -Wmicrosoft -verify=ms-anonymous-dis \ // RUN: -fno-ms-anonymous-structs -// Test that explicit -fno-ms-anonymous-structs does not enable the feature. -// RUN: %clang_cc1 -triple i686-windows %s -fsyntax-only -Wno-unused-value \ -// RUN: -Wno-pointer-to-int-cast -Wmicrosoft -verify=ms-anonymous-dis \ -// RUN: -fno-ms-anonymous-structs -// Test that explicit -fno-ms-anonymous-structs overrides -earlier fms-anonymous-structs. +// Test that explicit -fno-ms-anonymous-structs overrides earlier -fms-anonymous-structs. // RUN: %clang_cc1 -triple i686-windows %s -fsyntax-only -Wno-unused-value \ // RUN: -Wno-pointer-to-int-cast -Wmicrosoft -verify=ms-anonymous-dis \ // RUN: -fms-anonymous-structs -fno-ms-anonymous-structs >From 4c27d8d775ab5a5543881e5208e40d1a37a7cae5 Mon Sep 17 00:00:00 2001 From: Riyaz Ahmad <[email protected]> Date: Tue, 27 Jan 2026 12:05:13 -0500 Subject: [PATCH 12/15] [Driver][Frontend] Add -f[no-]ms-anonymous-structs flag to control Microsoft anonymous struct/union extension Add a Clang driver option -fms-anonymous-structs and -fno-ms-anonymous-structs to enable or disable Microsoft anonymous struct/union support independently of -fms-extensions. Motivation: - On some platforms (e.g. AIX), enabling -fms-extensions can conflict with system headers (such as usage of __ptr32). - Some codebases rely specifically on Microsoft anonymous struct/union behavior without requiring other Microsoft extensions. This change allows users to selectively enable the anonymous struct/union extension at the driver level without enabling full Microsoft compatibility mode. Behavior: - -fms-anonymous-structs enables the feature explicitly. - The feature is still enabled implicitly when -fms-extensions or -fms-compatibility is in effect. - Explicit enable/disable options follow last-option-wins semantics. - When multiple flags affect this feature, the last flag on the command determines the behavior. For example: -fms-extensions -fno-ms-anonymous-structs, disable the feature. -fno-ms-anonymous-structs -fms-anonymous-structs, enables the feature (last option wins). Implementation: - Added driver-level options -fms-anonymous-structs and -fno-ms-anonymous-structs. - Forwarded the option from the driver to CC1. - Added driver and frontend tests to verify option interactions. --- clang/docs/ReleaseNotes.rst | 2 +- clang/include/clang/Options/Options.td | 18 +++++------ clang/lib/Driver/ToolChains/Clang.cpp | 35 ++++++++++++++++++++++ clang/test/Driver/ms-anonymous-structs.c | 38 ++++++++++++++++++++++++ 4 files changed, 82 insertions(+), 11 deletions(-) create mode 100644 clang/test/Driver/ms-anonymous-structs.c diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index b8b2b83b58981..06fbb49ce6b32 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -109,7 +109,7 @@ Non-comprehensive list of changes in this release New Compiler Flags ------------------ -- New CC1 option ``-fms-anonymous-structs`` added to enable only Microsoft's anonymous struct/union extension without enabling other ``-fms-extensions`` features [GH177607]. +- New option ``-fms-anonymous-structs`` / ``-fno-ms-anonymous-structs`` added to enable or disable Microsoft's anonymous struct/union extension without enabling other ``-fms-extensions`` features [GH177607]. Deprecated Compiler Flags ------------------------- diff --git a/clang/include/clang/Options/Options.td b/clang/include/clang/Options/Options.td index dd7a0139484be..11df591f35e7f 100644 --- a/clang/include/clang/Options/Options.td +++ b/clang/include/clang/Options/Options.td @@ -3327,16 +3327,14 @@ 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]>; -defm fms_anonymous_structs - : BoolFOption<"ms-anonymous-structs", - LangOpts<"MSAnonymousStructs">, - DefaultFalse, - PosFlag<SetTrue, [], [CC1Option], - "Enable Microsoft anonymous struct/union extension.", - [fms_extensions.KeyPath]>, - NegFlag<SetFalse, [], [CC1Option], - "Disable Microsoft anonymous struct/union extension.">, - BothFlags<[], [CC1Option], " Microsoft anonymous struct/union extension">>; +defm ms_anonymous_structs + : BoolFOption< + "ms-anonymous-structs", LangOpts<"MSAnonymousStructs">, DefaultFalse, + PosFlag<SetTrue, [], [ClangOption, CC1Option], + "Enable Microsoft anonymous struct/union extension.", + [fms_extensions.KeyPath]>, + NegFlag<SetFalse, [], [ClangOption, CC1Option], + "Disable Microsoft anonymous struct/union extension.">>; 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..4d513c7500af0 100644 --- a/clang/lib/Driver/ToolChains/Clang.cpp +++ b/clang/lib/Driver/ToolChains/Clang.cpp @@ -7171,6 +7171,41 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA, CmdArgs.push_back("-fms-define-stdc"); } + // -fms-anonymous-struct=0 default. + bool EnableMSAnon = false; + bool SeenRelevantOption = false; + for (const Arg *A : Args) { + switch (A->getOption().getID()) { + case options::OPT_fms_anonymous_structs: + A->claim(); + EnableMSAnon = true; + SeenRelevantOption = true; + break; + case options::OPT_fno_ms_anonymous_structs: + A->claim(); + EnableMSAnon = false; + SeenRelevantOption = true; + break; + case options::OPT_fms_extensions: + case options::OPT_fms_compatibility: + EnableMSAnon = true; + SeenRelevantOption = true; + break; + case options::OPT_fno_ms_extensions: + case options::OPT_fno_ms_compatibility: + EnableMSAnon = false; + SeenRelevantOption = true; + break; + default: + break; + } + } + + if (SeenRelevantOption) { + CmdArgs.push_back(EnableMSAnon ? "-fms-anonymous-structs" + : "-fno-ms-anonymous-structs"); + } + if (Triple.isWindowsMSVCEnvironment() && !D.IsCLMode() && Args.hasArg(options::OPT_fms_runtime_lib_EQ)) ProcessVSRuntimeLibrary(getToolChain(), Args, CmdArgs); diff --git a/clang/test/Driver/ms-anonymous-structs.c b/clang/test/Driver/ms-anonymous-structs.c new file mode 100644 index 0000000000000..79723590ee6d4 --- /dev/null +++ b/clang/test/Driver/ms-anonymous-structs.c @@ -0,0 +1,38 @@ +// RUN: %clang -### -target powerpc-ibm-aix -fms-anonymous-structs %s 2>&1 | \ +// RUN: FileCheck %s --check-prefix=MS-STRUCT-ENABLE +// MS-STRUCT-ENABLE: "-fms-anonymous-structs" + +// RUN: %clang -### -target powerpc-ibm-aix -fno-ms-anonymous-structs %s 2>&1 | \ +// RUN: FileCheck %s --check-prefix=MS-STRUCT-DISABLE +// MS-STRUCT-DISABLE: "-fno-ms-anonymous-structs" + +// RUN: %clang -### -target powerpc-ibm-aix -fms-extensions %s 2>&1 | \ +// RUN: FileCheck %s --check-prefix=IMPLICIT-ENABLE +// IMPLICIT-ENABLE: "-fms-anonymous-structs" + +// RUN: %clang -### -target powerpc-ibm-aix -fms-compatibility %s 2>&1 | \ +// RUN: FileCheck %s --check-prefix=IMPLICIT-ENABLE + +// RUN: %clang -### -target powerpc-ibm-aix -fno-ms-anonymous-structs -fms-anonymous-structs %s 2>&1 |\ +// RUN: FileCheck %s --check-prefix=LAST-ENABLE +// LAST-ENABLE: "-fms-anonymous-structs" +// LAST-ENABLE-NOT: "-fno-ms-anonymous-structs" + +// RUN: %clang -### -target powerpc-ibm-aix -fno-ms-anonymous-structs -fms-extensions %s 2>&1 |\ +// RUN: FileCheck %s --check-prefix=LAST-ENABLE + +// RUN: %clang -### -target powerpc-ibm-aix -fms-anonymous-structs -fno-ms-anonymous-structs %s 2>&1 |\ +// RUN: FileCheck %s --check-prefix=LAST-DISABLE +// LAST-DISABLE: "-fno-ms-anonymous-structs" +// LAST-DISABLE-NOT: "-fms-anonymous-structs" + +// RUN: %clang -### -target powerpc-ibm-aix -fms-extensions -fno-ms-anonymous-structs %s 2>&1 |\ +// RUN: FileCheck %s --check-prefix=LAST-DISABLE + +// RUN: %clang -### -target powerpc-ibm-aix -fms-compatibility -fno-ms-anonymous-structs %s 2>&1 |\ +// RUN: FileCheck %s --check-prefix=LAST-DISABLE + +// RUN: %clang -### -target powerpc-ibm-aix %s 2>&1 | FileCheck %s --check-prefix=NO-MS-STRUCT +// NO-MS-STRUCT-NOT: "-fms-anonymous-structs" +// NO-MS-STRUCT-NOT: "-fno-ms-anonymous-structs" + >From 534698753bec7a6285673914f64805c3bd1d0d79 Mon Sep 17 00:00:00 2001 From: Riyaz Ahmad <[email protected]> Date: Wed, 28 Jan 2026 12:03:09 -0500 Subject: [PATCH 13/15] Address review comments and update LanguageExtensions.rst. --- clang/docs/LanguageExtensions.rst | 43 +++++++++++++++++++++++++++ clang/docs/ReleaseNotes.rst | 4 ++- clang/lib/Driver/ToolChains/Clang.cpp | 2 +- 3 files changed, 47 insertions(+), 2 deletions(-) diff --git a/clang/docs/LanguageExtensions.rst b/clang/docs/LanguageExtensions.rst index a734e5083f360..ec0e124ea7e69 100644 --- a/clang/docs/LanguageExtensions.rst +++ b/clang/docs/LanguageExtensions.rst @@ -2424,6 +2424,49 @@ Clang provides support for Microsoft extensions to support enumerations with no typedef enum empty { } A; +Microsoft Anonymous Structs and Unions +-------------------------------------- + +Clang provides support for a Microsoft extension that allows named struct or union types to be declared +as anonymous member inside another struct or union, making their fields directly accessible from the +enclosing type. + + +For example, consider the following code: + +.. code-block:: c + + struct Inner { + int x; + int y; + }; + + struct Outer { + struct Inner; /* Microsoft extension: named anonymous struct member */ + }; + + void f(struct Outer *o) { + o->x = 1; /* accesses Inner::x directly */ + o->y = 1; /* accesses Inner::y directly */ + } + +Without this extension, such declarations generate a warning that the declaration does not +declare anything and their members cannot be accessed directly. + +This extension can be controlled independently of other Microsoft extensions: + +* ``-fms-anonymous-structs`` + Enable named anonymous struct/union support + +* ``-fno-ms-anonymous-structs`` + Disable anonymous struct/union support + +This extension is also **implicitly enabled** when either of the following options is used: + +* ``-fms-extensions`` +* ``-fms-compatibility`` + +When multiple controlling options are specified, the last option on command line take precedence. Interoperability with C++11 lambdas ----------------------------------- diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index 06fbb49ce6b32..bfc504e6cbcb7 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -109,7 +109,9 @@ Non-comprehensive list of changes in this release New Compiler Flags ------------------ -- New option ``-fms-anonymous-structs`` / ``-fno-ms-anonymous-structs`` added to enable or disable Microsoft's anonymous struct/union extension without enabling other ``-fms-extensions`` features [GH177607]. +- New option ``-fms-anonymous-structs`` / ``-fno-ms-anonymous-structs`` added + to enable or disable Microsoft's anonymous struct/union extension without + enabling other ``-fms-extensions`` features (#GH177607). Deprecated Compiler Flags ------------------------- diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp index 4d513c7500af0..3b1ac8a6e6dd4 100644 --- a/clang/lib/Driver/ToolChains/Clang.cpp +++ b/clang/lib/Driver/ToolChains/Clang.cpp @@ -7171,7 +7171,7 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA, CmdArgs.push_back("-fms-define-stdc"); } - // -fms-anonymous-struct=0 default. + // -fms-anonymous-structs is disabled by default. bool EnableMSAnon = false; bool SeenRelevantOption = false; for (const Arg *A : Args) { >From 8b52cd75f55a47771a86e64a95557270e64852f9 Mon Sep 17 00:00:00 2001 From: Riyaz Ahmad <[email protected]> Date: Thu, 29 Jan 2026 08:54:18 -0500 Subject: [PATCH 14/15] [Driver][Frontend] Address review comments. --- clang/docs/LanguageExtensions.rst | 17 +++--- clang/lib/Driver/ToolChains/Clang.cpp | 79 ++++++++++++++++----------- 2 files changed, 57 insertions(+), 39 deletions(-) diff --git a/clang/docs/LanguageExtensions.rst b/clang/docs/LanguageExtensions.rst index ec0e124ea7e69..0d59ec9e98c9d 100644 --- a/clang/docs/LanguageExtensions.rst +++ b/clang/docs/LanguageExtensions.rst @@ -2427,10 +2427,9 @@ Clang provides support for Microsoft extensions to support enumerations with no Microsoft Anonymous Structs and Unions -------------------------------------- -Clang provides support for a Microsoft extension that allows named struct or union types to be declared -as anonymous member inside another struct or union, making their fields directly accessible from the -enclosing type. - +Clang provides support for a Microsoft extension that allows use of named struct or union types to +declare anonymous members inside another struct or union, making their fields directly accessible +from the enclosing type. For example, consider the following code: @@ -2446,12 +2445,13 @@ For example, consider the following code: }; void f(struct Outer *o) { - o->x = 1; /* accesses Inner::x directly */ - o->y = 1; /* accesses Inner::y directly */ + o->x = 1; /* accesses x member of anonymous member of type Inner directly */ + o->y = 1; /* accesses x member of anonymous member of type Inner directly */ } Without this extension, such declarations generate a warning that the declaration does not -declare anything and their members cannot be accessed directly. +declare anything, the associated member names are not available for access, and the layout +of types containing such declarations are affected accordingly. This extension can be controlled independently of other Microsoft extensions: @@ -2466,7 +2466,8 @@ This extension is also **implicitly enabled** when either of the following optio * ``-fms-extensions`` * ``-fms-compatibility`` -When multiple controlling options are specified, the last option on command line take precedence. +When multiple controlling options are specified, the last option on the command line takes +precedence. Interoperability with C++11 lambdas ----------------------------------- diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp index 3b1ac8a6e6dd4..19237fcd6085a 100644 --- a/clang/lib/Driver/ToolChains/Clang.cpp +++ b/clang/lib/Driver/ToolChains/Clang.cpp @@ -7172,39 +7172,56 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA, } // -fms-anonymous-structs is disabled by default. - bool EnableMSAnon = false; - bool SeenRelevantOption = false; - for (const Arg *A : Args) { - switch (A->getOption().getID()) { - case options::OPT_fms_anonymous_structs: - A->claim(); - EnableMSAnon = true; - SeenRelevantOption = true; - break; - case options::OPT_fno_ms_anonymous_structs: - A->claim(); - EnableMSAnon = false; - SeenRelevantOption = true; - break; - case options::OPT_fms_extensions: - case options::OPT_fms_compatibility: - EnableMSAnon = true; - SeenRelevantOption = true; - break; - case options::OPT_fno_ms_extensions: - case options::OPT_fno_ms_compatibility: - EnableMSAnon = false; - SeenRelevantOption = true; - break; - default: - break; + // Determine whether to enable Microsoft named anonymous struct/union support. + // This implements "last flag wins" semantics for -fms-anonymous-structs, + // where the feature can be: + // - Explicitly enabled via -fms-anonymous-structs. + // - Explicitly disabled via fno-ms-anonymous-structs + // - Implicitly enabled via -fms-extensions or -fms-compatibility + // - Implicitly disabled via -fno-ms-extensions or -fno-ms-compatibility + // + // When multiple relevent options are present, the last option on the command line + // takes precedence. This allows users to selectively override implicit enablement. + // Examples: + // -fms-extensions -fno-ms-anonymous-structs -> disabled (explicit override) + // -fno-ms-anonymous-structs -fms-extensions -> enabled (last flag wins) + auto ShouldEnableMSAnonymousStructs = + [&](const ArgList &Args) -> std::optional<bool> { + std::optional<bool> EnableAnonymousStructs; + + // Iterate through all arguments in order to implement "last flag wins". + for (const Arg *A : Args) { + switch (A->getOption().getID()) { + case options::OPT_fms_anonymous_structs: + A->claim(); + EnableAnonymousStructs = true; + break; + case options::OPT_fno_ms_anonymous_structs: + A->claim(); + EnableAnonymousStructs = false; + break; + // -fms-extensions and -fms-compatibility implicitly enables feature. + case options::OPT_fms_extensions: + case options::OPT_fms_compatibility: + EnableAnonymousStructs = true; + break; + // -fno-ms-extensions and -fno-ms-compatibility implicitly disable + // this feature. + case options::OPT_fno_ms_extensions: + case options::OPT_fno_ms_compatibility: + EnableAnonymousStructs = false; + break; + default: + break; + } } - } + return EnableAnonymousStructs; + }; - if (SeenRelevantOption) { - CmdArgs.push_back(EnableMSAnon ? "-fms-anonymous-structs" - : "-fno-ms-anonymous-structs"); - } + // Only pass a flag to CC1 if a relevant option was seen + if (auto MSAnon = ShouldEnableMSAnonymousStructs(Args)) + CmdArgs.push_back(*MSAnon ? "-fms-anonymous-structs" + : "-fno-ms-anonymous-structs"); if (Triple.isWindowsMSVCEnvironment() && !D.IsCLMode() && Args.hasArg(options::OPT_fms_runtime_lib_EQ)) >From 3c8f696394b67193ced8e3ba897d0ccf651d68a2 Mon Sep 17 00:00:00 2001 From: Riyaz Ahmad <[email protected]> Date: Thu, 29 Jan 2026 09:21:32 -0500 Subject: [PATCH 15/15] Address clang-format issue. --- clang/lib/Driver/ToolChains/Clang.cpp | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp index 19237fcd6085a..a6cd72048522d 100644 --- a/clang/lib/Driver/ToolChains/Clang.cpp +++ b/clang/lib/Driver/ToolChains/Clang.cpp @@ -7180,9 +7180,9 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA, // - Implicitly enabled via -fms-extensions or -fms-compatibility // - Implicitly disabled via -fno-ms-extensions or -fno-ms-compatibility // - // When multiple relevent options are present, the last option on the command line - // takes precedence. This allows users to selectively override implicit enablement. - // Examples: + // When multiple relevent options are present, the last option on the command + // line takes precedence. This allows users to selectively override implicit + // enablement. Examples: // -fms-extensions -fno-ms-anonymous-structs -> disabled (explicit override) // -fno-ms-anonymous-structs -fms-extensions -> enabled (last flag wins) auto ShouldEnableMSAnonymousStructs = _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
