https://github.com/vsapsai updated https://github.com/llvm/llvm-project/pull/221039
>From ca0d3577a12d3ff3a23377add7d02ad03add1fa9 Mon Sep 17 00:00:00 2001 From: Volodymyr Sapsai <[email protected]> Date: Wed, 2 Sep 2026 23:52:33 -0700 Subject: [PATCH 1/2] [clang] Diagnose when spelled 'abi_tag' on namespace doesn't match applied one. 'abi_tag' on a namespace means applying it to decls within this namespace. You can reopen a namespace with the same name later. And in this case clang uses 'abi_tag' from the canonical namespace decl, not the attribute specified for this reopened namespace. This difference between the spelled and applied 'abi_tag' can be unexpected and confusing. Don't change the existing behavior but add a diagnostic notifying about such mismatches. --- clang/docs/ReleaseNotes.md | 5 ++ clang/include/clang/Basic/DiagnosticGroups.td | 2 + .../clang/Basic/DiagnosticSemaKinds.td | 6 ++ clang/lib/Sema/SemaDecl.cpp | 61 ++++++++++++++----- clang/lib/Sema/SemaDeclCXX.cpp | 3 +- clang/test/SemaCXX/attr-abi-tag-syntax.cpp | 26 +++++++- 6 files changed, 85 insertions(+), 18 deletions(-) diff --git a/clang/docs/ReleaseNotes.md b/clang/docs/ReleaseNotes.md index a1f24a8caedae..a5f8fb5a971f3 100644 --- a/clang/docs/ReleaseNotes.md +++ b/clang/docs/ReleaseNotes.md @@ -518,6 +518,11 @@ features cannot lower the translation-unit ABI level; - Improve Clang diagnoses when unary `__imag` operator with non-complex type operand is used as lvalue. (GH222383) +- Added `-Wabi-tag` to diagnose when the `abi_tag` attribute spelled on a + namespace declaration doesn't match the one actually applied, which is taken + from the first declaration of that namespace. The diagnostic is an error by + default and can be downgraded with `-Wno-error=abi-tag`. + ### Improvements to Clang's time-trace ### Improvements to Coverage Mapping diff --git a/clang/include/clang/Basic/DiagnosticGroups.td b/clang/include/clang/Basic/DiagnosticGroups.td index 1da7698944b24..9435578145ddf 100644 --- a/clang/include/clang/Basic/DiagnosticGroups.td +++ b/clang/include/clang/Basic/DiagnosticGroups.td @@ -1868,6 +1868,8 @@ def UnknownArgument : DiagGroup<"unknown-argument">; def UnsupportedABI : DiagGroup<"unsupported-abi">; +def IgnoredAbiTagAttr : DiagGroup<"abi-tag">; + // A warning group for warnings about code that clang accepts when // compiling OpenCL C/C++ but which is not compatible with the SPIR(-V) spec. def SpirCompat : DiagGroup<"spir-compat">; diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td index fca68f292f667..82911fa7a9601 100644 --- a/clang/include/clang/Basic/DiagnosticSemaKinds.td +++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td @@ -6492,6 +6492,12 @@ def err_redefinition_extern_inline : Error< def warn_attr_abi_tag_namespace : Warning< "'abi_tag' attribute on %select{non-inline|anonymous}0 namespace ignored">, InGroup<IgnoredAttributes>; +def warn_abi_tag_ignored_missing : Warning< + "absent 'abi_tag' attribute is ignored, applying 'abi_tag' %0">, + InGroup<IgnoredAbiTagAttr>, DefaultError; +def warn_abi_tag_ignored_different : Warning< + "'abi_tag' %0 is ignored, applying %select{no 'abi_tag'|'abi_tag' %2}1">, + InGroup<IgnoredAbiTagAttr>, DefaultError; def err_abi_tag_on_redeclaration : Error< "cannot add 'abi_tag' attribute in a redeclaration">; def err_new_abi_tag_on_redeclaration : Error< diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp index e52f99b4cd98d..9f6949d853f09 100644 --- a/clang/lib/Sema/SemaDecl.cpp +++ b/clang/lib/Sema/SemaDecl.cpp @@ -2961,11 +2961,13 @@ static bool mergeDeclAttribute(Sema &S, NamedDecl *D, AA->getDeprecated(), AA->getObsoleted(), AA->getUnavailable(), AA->getMessage(), AA->getStrict(), AA->getReplacement(), AMK, AA->getPriority(), AA->getEnvironment(), InferredPlatformII); - } else if (const auto *VA = dyn_cast<VisibilityAttr>(Attr)) - NewAttr = S.mergeVisibilityAttr(D, *VA, VA->getVisibility()); - else if (const auto *VA = dyn_cast<TypeVisibilityAttr>(Attr)) - NewAttr = S.mergeTypeVisibilityAttr(D, *VA, VA->getVisibility()); - else if (const auto *ImportA = dyn_cast<DLLImportAttr>(Attr)) + } else if (const auto *VA = dyn_cast<VisibilityAttr>(Attr)) { + if (!isa<NamespaceDecl>(D)) + NewAttr = S.mergeVisibilityAttr(D, *VA, VA->getVisibility()); + } else if (const auto *VA = dyn_cast<TypeVisibilityAttr>(Attr)) { + if (!isa<NamespaceDecl>(D)) + NewAttr = S.mergeTypeVisibilityAttr(D, *VA, VA->getVisibility()); + } else if (const auto *ImportA = dyn_cast<DLLImportAttr>(Attr)) NewAttr = S.mergeDLLImportAttr(D, *ImportA); else if (const auto *ExportA = dyn_cast<DLLExportAttr>(Attr)) NewAttr = S.mergeDLLExportAttr(D, *ExportA); @@ -3368,20 +3370,47 @@ void Sema::mergeDeclAttributes(NamedDecl *New, Decl *Old, } } - // Re-declaration cannot add abi_tag's. - if (const auto *NewAbiTagAttr = New->getAttr<AbiTagAttr>()) { - if (const auto *OldAbiTagAttr = Old->getAttr<AbiTagAttr>()) { - for (const auto &NewTag : NewAbiTagAttr->tags()) { - if (!llvm::is_contained(OldAbiTagAttr->tags(), NewTag)) { - Diag(NewAbiTagAttr->getLocation(), - diag::err_new_abi_tag_on_redeclaration) - << NewTag; + if (isa<NamespaceDecl>(New)) { + Decl *ComparedOld = Old->getCanonicalDecl(); + if (const auto *NewAbiTagAttr = New->getAttr<AbiTagAttr>()) { + if (const auto *OldAbiTagAttr = ComparedOld->getAttr<AbiTagAttr>()) { + bool Diff = NewAbiTagAttr->tags_size() != OldAbiTagAttr->tags_size(); + if (!Diff) + Diff = !llvm::all_of(NewAbiTagAttr->tags(), [OldAbiTagAttr](StringRef NewTag) { + return llvm::is_contained(OldAbiTagAttr->tags(), NewTag); + }); + if (Diff) { + Diag(NewAbiTagAttr->getLocation(), diag::warn_abi_tag_ignored_different) << llvm::join(NewAbiTagAttr->tags(), ", ") << true << llvm::join(OldAbiTagAttr->tags(), ", "); Diag(OldAbiTagAttr->getLocation(), diag::note_previous_declaration); } + } else { + Diag(NewAbiTagAttr->getLocation(), diag::warn_abi_tag_ignored_different) << llvm::join(NewAbiTagAttr->tags(), ", ") << false; + Diag(ComparedOld->getLocation(), diag::note_previous_declaration); + } + } else if (const auto *OldAbiTagAttr = ComparedOld->getAttr<AbiTagAttr>()) { + Diag(New->getLocation(), diag::warn_abi_tag_ignored_missing) << llvm::join(OldAbiTagAttr->tags(), ", "); + Diag(OldAbiTagAttr->getLocation(), diag::note_previous_declaration); + } + } else { + // Re-declaration cannot add abi_tag's. + if (const auto *NewAbiTagAttr = New->getAttr<AbiTagAttr>()) { + if (const auto *OldAbiTagAttr = Old->getAttr<AbiTagAttr>()) { + for (const auto &NewTag : NewAbiTagAttr->tags()) { + if (!llvm::is_contained(OldAbiTagAttr->tags(), NewTag)) { + if (isa<NamespaceDecl>(New)) { + Diag(NewAbiTagAttr->getLocation(), diag::warn_abi_tag_ignored_different) << NewTag << true << llvm::join(OldAbiTagAttr->tags(), ", "); + } else { + Diag(NewAbiTagAttr->getLocation(), + diag::err_new_abi_tag_on_redeclaration) + << NewTag; + } + Diag(OldAbiTagAttr->getLocation(), diag::note_previous_declaration); + } + } + } else { + Diag(NewAbiTagAttr->getLocation(), diag::err_abi_tag_on_redeclaration); + Diag(Old->getLocation(), diag::note_previous_declaration); } - } else { - Diag(NewAbiTagAttr->getLocation(), diag::err_abi_tag_on_redeclaration); - Diag(Old->getLocation(), diag::note_previous_declaration); } } diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp index 3639640f2886a..e0c70ff07f447 100644 --- a/clang/lib/Sema/SemaDeclCXX.cpp +++ b/clang/lib/Sema/SemaDeclCXX.cpp @@ -12102,9 +12102,10 @@ Decl *Sema::ActOnStartNamespaceDef(Scope *NamespcScope, AddPragmaAttributes(DeclRegionScope, Namespc); ProcessAPINotes(Namespc); - // FIXME: Should we be merging attributes? if (const VisibilityAttr *Attr = Namespc->getAttr<VisibilityAttr>()) PushNamespaceVisibilityAttr(Attr, Loc); + if (PrevNS) + mergeDeclAttributes(Namespc, PrevNS); if (IsStd) StdNamespace = Namespc; diff --git a/clang/test/SemaCXX/attr-abi-tag-syntax.cpp b/clang/test/SemaCXX/attr-abi-tag-syntax.cpp index 4f14a3c043b5c..2ed24c83cc0b4 100644 --- a/clang/test/SemaCXX/attr-abi-tag-syntax.cpp +++ b/clang/test/SemaCXX/attr-abi-tag-syntax.cpp @@ -17,7 +17,31 @@ inline namespace __attribute__((__abi_tag__)) {} inline namespace N __attribute__((__abi_tag__)) {} -} // namespcace N2 +} // namespace N2 + +namespace N3 { +inline namespace AbsentOld {} +inline namespace AbsentOld __attribute__((__abi_tag__)) {} +// expected-error@-1 {{'abi_tag' AbsentOld is ignored, applying no 'abi_tag'}} +// expected-note@-3 {{previous declaration is here}} + +inline namespace AbsentNew __attribute__((__abi_tag__)) {} +inline namespace AbsentNew {} +// expected-error@-1 {{absent 'abi_tag' attribute is ignored, applying 'abi_tag' AbsentNew}} +// expected-note@-3 {{previous declaration is here}} + +inline namespace Different __attribute__((abi_tag("A"))) {} +inline namespace Different __attribute__((abi_tag("B"))) {} +// expected-error@-1 {{'abi_tag' B is ignored, applying 'abi_tag' A}} +// expected-note@-3 {{previous declaration is here}} +inline namespace Different __attribute__((abi_tag("A"))) {} +// No error as we compare with the canonical namespace decl, not with the previous one. + +inline namespace MultipleTags __attribute__((abi_tag("A", "B"))) {} +inline namespace MultipleTags __attribute__((abi_tag("X", "Y", "B"))) {} +// expected-error@-1 {{'abi_tag' B, X, Y is ignored, applying 'abi_tag' A, B}} +// expected-note@-3 {{previous declaration is here}} +} // namespace N3 __attribute__((abi_tag("B", "A"))) extern int a1; >From b2df4615cdf6dd60d2f7a7fa5561b44d118ab227 Mon Sep 17 00:00:00 2001 From: Volodymyr Sapsai <[email protected]> Date: Thu, 3 Sep 2026 13:33:59 -0700 Subject: [PATCH 2/2] Fix formatting. --- clang/lib/Sema/SemaDecl.cpp | 24 ++++++++++++++++-------- 1 file changed, 16 insertions(+), 8 deletions(-) diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp index 9f6949d853f09..93a2b11a9e3dc 100644 --- a/clang/lib/Sema/SemaDecl.cpp +++ b/clang/lib/Sema/SemaDecl.cpp @@ -3376,19 +3376,25 @@ void Sema::mergeDeclAttributes(NamedDecl *New, Decl *Old, if (const auto *OldAbiTagAttr = ComparedOld->getAttr<AbiTagAttr>()) { bool Diff = NewAbiTagAttr->tags_size() != OldAbiTagAttr->tags_size(); if (!Diff) - Diff = !llvm::all_of(NewAbiTagAttr->tags(), [OldAbiTagAttr](StringRef NewTag) { - return llvm::is_contained(OldAbiTagAttr->tags(), NewTag); - }); + Diff = !llvm::all_of( + NewAbiTagAttr->tags(), [OldAbiTagAttr](StringRef NewTag) { + return llvm::is_contained(OldAbiTagAttr->tags(), NewTag); + }); if (Diff) { - Diag(NewAbiTagAttr->getLocation(), diag::warn_abi_tag_ignored_different) << llvm::join(NewAbiTagAttr->tags(), ", ") << true << llvm::join(OldAbiTagAttr->tags(), ", "); + Diag(NewAbiTagAttr->getLocation(), + diag::warn_abi_tag_ignored_different) + << llvm::join(NewAbiTagAttr->tags(), ", ") << true + << llvm::join(OldAbiTagAttr->tags(), ", "); Diag(OldAbiTagAttr->getLocation(), diag::note_previous_declaration); } } else { - Diag(NewAbiTagAttr->getLocation(), diag::warn_abi_tag_ignored_different) << llvm::join(NewAbiTagAttr->tags(), ", ") << false; + Diag(NewAbiTagAttr->getLocation(), diag::warn_abi_tag_ignored_different) + << llvm::join(NewAbiTagAttr->tags(), ", ") << false; Diag(ComparedOld->getLocation(), diag::note_previous_declaration); } } else if (const auto *OldAbiTagAttr = ComparedOld->getAttr<AbiTagAttr>()) { - Diag(New->getLocation(), diag::warn_abi_tag_ignored_missing) << llvm::join(OldAbiTagAttr->tags(), ", "); + Diag(New->getLocation(), diag::warn_abi_tag_ignored_missing) + << llvm::join(OldAbiTagAttr->tags(), ", "); Diag(OldAbiTagAttr->getLocation(), diag::note_previous_declaration); } } else { @@ -3398,11 +3404,13 @@ void Sema::mergeDeclAttributes(NamedDecl *New, Decl *Old, for (const auto &NewTag : NewAbiTagAttr->tags()) { if (!llvm::is_contained(OldAbiTagAttr->tags(), NewTag)) { if (isa<NamespaceDecl>(New)) { - Diag(NewAbiTagAttr->getLocation(), diag::warn_abi_tag_ignored_different) << NewTag << true << llvm::join(OldAbiTagAttr->tags(), ", "); + Diag(NewAbiTagAttr->getLocation(), + diag::warn_abi_tag_ignored_different) + << NewTag << true << llvm::join(OldAbiTagAttr->tags(), ", "); } else { Diag(NewAbiTagAttr->getLocation(), diag::err_new_abi_tag_on_redeclaration) - << NewTag; + << NewTag; } Diag(OldAbiTagAttr->getLocation(), diag::note_previous_declaration); } _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
