r188510 - Fix for dependent contexts in alias templates.

[Eli Friedman]

On Thu, Aug 15, 2013 at 4:59 PM, Eli Friedman <eli.friedman at gmail.com>wrote:

> Author: efriedma
> Date: Thu Aug 15 18:59:20 2013
> New Revision: 188510
>
> URL: http://llvm.org/viewvc/llvm-project?rev=188510&view=rev
> Log:
> Fix for dependent contexts in alias templates.
>
> When we are parsing a type for an alias template, we are not entering
> the context, so we can't look into dependent classes.  Make sure the
> parser handles this correctly.
>
> PR16904.
>
> Modified:
>     cfe/trunk/lib/Parse/ParseDecl.cpp
>     cfe/trunk/test/SemaTemplate/alias-templates.cpp
>
> Modified: cfe/trunk/lib/Parse/ParseDecl.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Parse/ParseDecl.cpp?rev=188510&r1=188509&r2=188510&view=diff
>
> ==============================================================================
> --- cfe/trunk/lib/Parse/ParseDecl.cpp (original)
> +++ cfe/trunk/lib/Parse/ParseDecl.cpp Thu Aug 15 18:59:20 2013
> @@ -2436,7 +2436,7 @@ void Parser::ParseDeclarationSpecifiers(
>
>      case tok::coloncolon: // ::foo::bar
>        // C++ scope specifier.  Annotate and loop, or bail out on error.
> -      if (TryAnnotateCXXScopeToken(true)) {
> +      if (TryAnnotateCXXScopeToken(EnteringContext)) {
>          if (!DS.hasTypeSpecifier())
>            DS.SetTypeSpecError();
>          goto DoneWithDeclSpec;
> @@ -2632,7 +2632,7 @@ void Parser::ParseDeclarationSpecifiers(
>        // In C++, check to see if this is a scope specifier like
> foo::bar::, if
>        // so handle it as such.  This is important for ctor parsing.
>        if (getLangOpts().CPlusPlus) {
> -        if (TryAnnotateCXXScopeToken(true)) {
> +        if (TryAnnotateCXXScopeToken(EnteringContext)) {
>            if (!DS.hasTypeSpecifier())
>              DS.SetTypeSpecError();
>            goto DoneWithDeclSpec;
>
>

Ugh... I just spent some more time thinking about this; while this fix
doesn't break anything as far as I know, it isn't really complete.
 Consider the following testcase:

template <typename,typename>

struct base {

  template <typename> struct derived;

};

template <typename T, typename U, typename V> base<T, U>::derived<V> foo();

There's a missing typename keyword, but clang fails to detect this.  Any
suggestions?

-Eli
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