[CLANG] Alignment specifier not applied to anonymous structure or union

[kamleshbhalui]

Summary

Apply attributes on anonymous records.
This Fixes https://bugs.llvm.org/show_bug.cgi?id=43983.

[rsmith]

clang/lib/Sema/SemaDecl.cpp

5039

Should we apply the attributes to the variable in this case, or (if they're always syntactically invalid) assert that there aren't any?

[kamleshbhalui]

added assert.

[rsmith]

Seems fine to me. @aaron.ballman, want to take a look?

[aaron.ballman]

LGTM!

clang/test/AST/pr43983.cpp

2

You can drop the -std=c++11 here (we default to > c++11 anyway).

[kamleshbhalui]

removed c++11 from the test.
I do not have commit access, Can someone commit this for me?

[aaron.ballman]

In D71619#1791961, @kamleshbhalui wrote:

removed c++11 from the test.
I do not have commit access, Can someone commit this for me?

Thank you for the patch! I've commit on your behalf in 304d1304b7bac190b6c9733eb07be284bfc17030

clang/lib/Sema/SemaDecl.cpp

Decl *Sema::BuildAnonymousStructOrUnion(Scope *S, DeclSpec &DS,
   NamedDecl *Anon = nullptr;
   if (RecordDecl *OwningClass = dyn_cast<RecordDecl>(Owner)) {
     Anon = FieldDecl::Create(
         Context, OwningClass, DS.getBeginLoc(), Record->getLocation(),
         /*IdentifierInfo=*/nullptr, Context.getTypeDeclType(Record), TInfo,
         /*BitWidth=*/nullptr, /*Mutable=*/false,
         /*InitStyle=*/ICIS_NoInit);
     Anon->setAccess(AS);
+    ProcessDeclAttributes(S, Anon, Dc);
+
     if (getLangOpts().CPlusPlus)
       FieldCollector->Add(cast<FieldDecl>(Anon));
   } else {
     DeclSpec::SCS SCSpec = DS.getStorageClassSpec();
     StorageClass SC = StorageClassSpecToVarDeclStorageClass(DS);
     if (SCSpec == DeclSpec::SCS_mutable) {
       // mutable can only appear on non-static class members, so it's always
       // an error here
       Diag(Record->getLocation(), diag::err_mutable_nonmember);
       Invalid = true;
       SC = SC_None;
     }
 
+    assert(DS.getAttributes().empty() && "No attribute expected");
     Anon = VarDecl::Create(Context, Owner, DS.getBeginLoc(),
                            Record->getLocation(), /*IdentifierInfo=*/nullptr,
                            Context.getTypeDeclType(Record), TInfo, SC);
 
     // Default-initialize the implicit variable. This initialization will be
     // trivial in almost all cases, except if a union member has an in-class
     // initializer:
     //   union { int n = 0; };
     ActOnUninitializedDecl(Anon);

clang/test/AST/pr43983.cpp

+// RUN: %clang_cc1 -fsyntax-only %s -ast-dump | FileCheck %s
+
+struct B { _Alignas(64) struct { int b; };   };
+
+// CHECK: AlignedAttr {{.*}} _Alignas
+// CHECK: ConstantExpr {{.*}} 64
+// CHECK: IntegerLiteral {{.*}} 64