[clang] [clang][Sema] Improve template argument deduction diagnostic (PR #122754)

[Matheus Izvekov via cfe-commits]

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@@ -11714,13 +11714,37 @@ static void DiagnoseBadDeduction(Sema &S, NamedDecl *Found, Decl *Templated,
     return;
   }
 
-  case TemplateDeductionResult::InvalidExplicitArguments:
+  case TemplateDeductionResult::InvalidExplicitArguments: {
     assert(ParamD && "no parameter found for invalid explicit arguments");
-    if (ParamD->getDeclName())
-      S.Diag(Templated->getLocation(),
-             diag::note_ovl_candidate_explicit_arg_mismatch_named)
-          << ParamD->getDeclName();
-    else {
+    if (ParamD->getDeclName()) {
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mizvekov wrote:

I see, if you think that's too much information in one diagnostic, you can split that out.
For example, we do already have a note for pointing out a template parameter for other diagnostics, see `NoteTemplateParameterLocation` in `clang/lib/Sema/SemaTemplate.cpp`.

https://github.com/llvm/llvm-project/pull/122754