This adjusts the handling for:
export module M;
export namespace {};
export namespace N {};
export using namespace N;
In the first case, we were allowing empty anonymous namespaces
as part of an extension allowing empty top-level entities, but that seems
inappropriate in this case, since the linkage would be internal for the
anonymous namespace. We now report an error for this.
The second case was producing a warning diagnostic that this was
accepted as an extension - however the C++20 standard does allow this
as well-formed.
In the third case we keep the current practice that this is accepted with a
warning (as an extension). The C++20 standard says it's an error.
We also ensure that using decls are only applied to items with external linkage.
This adjusts error messages for exports involving redeclarations in modules to
be more specific about the reason that the decl has been rejected.
Differential Revision: https://reviews.llvm.org/D122119
Since only the decls inhabit in a namespace scope could be exported, it
is not meaningful to check it in CheckRedeclarationExported, which
implements [module.interface]/p6.
Reviewed By: urnathan
Differential Revision: https://reviews.llvm.org/D118120
This fixes bug 47716.
According to [module.interface]p2, it is meaningless to export an entity
which is not in namespace scope.
The reason why the compiler crashes is that the compiler missed
ExportDecl when the compiler traverse the subclass of DeclContext. So
here is the crash.
Also, the patch implements [module.interface]p6 in
Sema::CheckRedeclaration* functions.
Reviewed By: aaron.ballman, urnathan
Differential Revision: https://reviews.llvm.org/D112903
Iain Sandoe