Replace "failed template argument deduction" diagnostic with something useful

in the one case where we've already factored out a reason code.

llvm-svn: 174036

1 files changed, 22 insertions, 2 deletions

diff --git a/clang/lib/Sema/SemaOverload.cpp b/clang/lib/Sema/SemaOverload.cpp
index 22cb61eda39..dbab7398328 100644
--- a/clang/lib/Sema/SemaOverload.cpp
+++ b/clang/lib/Sema/SemaOverload.cpp
@@ -588,8 +588,11 @@ static MakeDeductionFailureInfo(ASTContext &Context,
     }
     break;
 
-  case Sema::TDK_NonDeducedMismatch:
   case Sema::TDK_FailedOverloadResolution:
+    Result.Data = Info.Expression;
+    break;
+
+  case Sema::TDK_NonDeducedMismatch:
     break;
   }
 
@@ -741,6 +744,15 @@ OverloadCandidate::DeductionFailureInfo::getSecondArg() {
   return 0;
 }
 
+Expr *
+OverloadCandidate::DeductionFailureInfo::getExpr() {
+  if (static_cast<Sema::TemplateDeductionResult>(Result) ==
+        Sema::TDK_FailedOverloadResolution)
+    return static_cast<Expr*>(Data);
+
+  return 0;
+}
+
 void OverloadCandidateSet::destroyCandidates() {
   for (iterator i = begin(), e = end(); i != e; ++i) {
     for (unsigned ii = 0, ie = i->NumConversions; ii != ie; ++ii)
@@ -8442,10 +8454,18 @@ void DiagnoseBadDeduction(Sema &S, OverloadCandidate *Cand,
     return;
   }
 
+  case Sema::TDK_FailedOverloadResolution: {
+    OverloadExpr::FindResult R =
+        OverloadExpr::find(Cand->DeductionFailure.getExpr());
+    S.Diag(Fn->getLocation(),
+           diag::note_ovl_candidate_failed_overload_resolution)
+      << R.Expression->getName();
+    return;
+  }
+
   // TODO: diagnose these individually, then kill off
   // note_ovl_candidate_bad_deduction, which is uselessly vague.
   case Sema::TDK_NonDeducedMismatch:
-  case Sema::TDK_FailedOverloadResolution:
     S.Diag(Fn->getLocation(), diag::note_ovl_candidate_bad_deduction);
     MaybeEmitInheritedConstructorNote(S, Fn);
     return;