[PATCH] D110216: [clang] retain type sugar in auto / template argument deduction

[Matheus Izvekov via Phabricator via cfe-commits]

mizvekov added inline comments.


================
Comment at: clang/lib/Sema/SemaTemplateDeduction.cpp:1643
 
-      return Param == Arg? Sema::TDK_Success : Sema::TDK_NonDeducedMismatch;
+      return ParDesug == ArgDesug ? Sema::TDK_Success
+                                  : Sema::TDK_NonDeducedMismatch;
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rsmith wrote:
> This looks wrong to me: we should be comparing the types, not how they're written. `Context.hasSameType(Param, Arg)` (or `Context.hasSameUnqualifiedType(Param, Arg)` in the `TDF_IgnoreQualifiers` case) would be appropriate here.
You are right, but the reason we don't get into any troubles here is because this is dead code anyway, the non-dependent case will always be handled above :)

Although perhaps, I wonder if we should dig down into non-dependent types anyway, in case the types are too complex and it's not immediately obvious what does not match, we could perhaps improve the diagnostic?

I will experiment a little bit with this idea.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D110216/new/

https://reviews.llvm.org/D110216