[cfe-dev] UsingDirectiveDecl inconsistently (not) added to their DeclContext.

[Enea Zaffanella]

Ping.

On 08/06/2012 04:30 PM, Enea Zaffanella wrote:
> We are observing an inconsistency (affecting our AST visitors) in the
> addition of UsingDirectiveDecl to their DeclContext.
>
> When parsing a using directive, it gets added to its DeclContext only if
> it is NOT a function/method:
>
> ===================== SemaDeclCXX.cpp
> void Sema::PushUsingDirective(Scope *S, UsingDirectiveDecl *UDir) {
>     // If the scope has an associated entity and the using directive is at
>     // namespace or translation unit scope, add the UsingDirectiveDecl into
>     // its lookup structure so qualified name lookup can find it.
>     DeclContext *Ctx = static_cast<DeclContext*>(S->getEntity());
>     if (Ctx && !Ctx->isFunctionOrMethod())
>       Ctx->addDecl(UDir);
> =====================
>
>
> However, when such a using declaration is subject to template
> instantiations, it is unconditionally added to its DeclContext, no
> matter if it is a function/method or not:
>
> ===================== SemaTemplateInstantiateDecl.cpp
> Decl
> *TemplateDeclInstantiator::VisitUsingDirectiveDecl(UsingDirectiveDecl *D) {
>     // Using directives are never dependent (and never contain any types or
>     // expressions), so they require no explicit instantiation work.
>
>     UsingDirectiveDecl *Inst
>       = UsingDirectiveDecl::Create(SemaRef.Context, Owner, D->getLocation(),
>                                    D->getNamespaceKeyLocation(),
>                                    D->getQualifierLoc(),
>                                    D->getIdentLocation(),
>                                    D->getNominatedNamespace(),
>                                    D->getCommonAncestor());
>     Owner->addDecl(Inst);
> =====================
>
> Therefore, when visiting the instantiated DeclContext we will see more
> declarations than when visiting its instantiation pattern.
> We would like to remove this inconsistency, but it is unclear to us
> which is the right fix to apply: should we always add the using
> declaration to its DeclContext or should we repeat the check for
> function/method when instantiating?
>
> Enea.
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