[cfe-dev] Help with integral template argument suffix and cast printing

[David Rector via cfe-dev]

I would try replacing

 else if (auto *DT = T->getContainedDeducedType())

with

  else if (auto *DT = T->getAs<DeducedType>())

I think that is what you want anyway, since getContainedDeducedType seems to look not only through type sugar but through pointee types, array element types, etc.

To be sure, your example still should have worked using getContainedDeducedType but I think GetContainedDeducedTypeVisitor may have a problem in its implementation: it doesn’t handle all the possible sugar types.   In this case, you probably have a SubstTemplateTypeParmType, and I don’t see a VisitSubstTemplateTypeParmType implementation in there anywhere, so it is probably returning nullptr instead of desugaring and continuing to search.  That’s my best guess anyway from my perusal.

If this change works, it is probably another reason to replace stuff like GetContainedDeducedTypeVisitor with a more advanced getAs<T>(), with an extra template param that would allow you to look through e.g. pointee types, element types, function return types etc. when desired.

If that doesn’t work though, disregard.  Good luck,

Dave

> On Jul 21, 2020, at 9:06 AM, Pratyush Das via cfe-dev <cfe-dev at lists.llvm.org> wrote:
> 
> Hi, 
> 
> I am a little stuck with https://reviews.llvm.org/D77598 <https://reviews.llvm.org/D77598> and would really appreciate any help.
> 
> I am trying to get the proper suffixes in the error messages for the following two examples - 
> 
> template<auto N> struct S {};
> template<> struct S<1> { using type = int };
> S<1L>::type t;
> 
> which should give the error message with a suffix - 
> error: no type named 'type' in 'S<1L>'; did you mean 'S<1>::type'?
> 
> and
> 
> template <unsigned long long N> struct enable_if_unsigned_long_long {};
> template <> struct enable_if_unsigned_long_long<1> { typedef int type; }; 
> void test_unsigned_long_long() { enable_if_unsigned_long_long<2>::type i; } 
> 
> which should give no suffix in the error message - 
> error: no type named 'type' in 'enable_if_unsigned_int<2>'; did you mean 'enable_if_unsigned_int<1>::type'?
> 
> I am trying to find the correct combination that would enable suffix in the first case, but not in the second case. I have been tinkering with checks for DeducedType and DependentType, but always either the suffixes are disabled for both the cases, or enabled for both the cases. 
> 
> Can anyone please provide any insight on how to proceed?
> 
> Thanks!
> 
> -- 
> Pratyush Das(Reik)
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