[PATCH] PR16909: Diagnose missing 'typename' on dependent template

[Ben Langmuir]

I tried to replicate the way the existing ‘missing typename’ diagnostic behaved for MSVC compatibility.  Is there something more that needs to be done here?  I’m not sure how I can verify that the resulting IR is correct on Windows, though...

> +void Sema::diagnoseMissingTypename(IdentifierInfo *II, SourceLocation IILoc,
> +                                   Scope *S, CXXScopeSpec *SS) {
> +  unsigned DiagID = diag::err_typename_missing;
> +  if (getLangOpts().MSVCCompat && isMicrosoftMissingTypename(SS, S))
> +    DiagID = diag::ext_typename_missing;

Ben

> On Feb 11, 2015, at 7:34 PM, Bataev, Alexey <a.bataev at gmx.com> wrote:
> 
> Hi Ben,
> I don't think your patch is compatible with MSVC. MSVC accepts this code and clang should accept it and generate proper LLVM IR. Actually, you can run into similar code in MSVC system headers. That's the main problem
> Best regards,
> Alexey Bataev
> =============
> Software Engineer
> Intel Compiler Team
> Intel Corp. 
> 11.02.2015 20:37, Ben Langmuir пишет:
>> Ping
>> 
>>> On Jan 26, 2015, at 9:08 AM, Ben Langmuir <blangmuir at apple.com <mailto:blangmuir at apple.com>> wrote:
>>> 
>>> This patch diagnoses a missing ‘typename’ keyword on nested template types like A<T>::B<U>, to fix llvm.org/pr16909 <http://llvm.org/pr16909>. In addition to fixing an accepts-invalid, in C++11 such types would cause assertion failures and/or invalid LLVM IR when used with ‘auto’.
>>> 
>>> I’m not 100% sure if the changes to test/CXX/basic/basic.lookup/basic.lookup.qual/class.qual/p2.cpp are desirable, or if we should suppress the missing ‘typename’ diagnostic when we’re already recovering on X<T>::X<T>.  I’m open to suggestions :-)
>>> 
>>> Ben
>>> 
>>> <pr16909.patch>
>> 
> 

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