Produce a special diagnostic when users call a function with an argument of

incomplete type (or a pointer/reference to such).

The causes of this problem are different enough to justify a different "design"
for the diagnostic.  Most notably, it doesn't give an operand index:
it's usually pretty obvious which operand is the problem, it adds a lot of
clutter to mention it, and the fix is usually in a different part of the file
anyway.

This is yet another diagnostic that should really have an analogue in the
non-overloaded case --- which should be much easier to write because of
the weaker space constraints.

llvm-svn: 94303

1 files changed, 16 insertions, 1 deletions

diff --git a/clang/lib/Sema/SemaOverload.cpp b/clang/lib/Sema/SemaOverload.cpp
index 9297f36318f..44a8f15e57b 100644
--- a/clang/lib/Sema/SemaOverload.cpp
+++ b/clang/lib/Sema/SemaOverload.cpp
@@ -4414,7 +4414,8 @@ void DiagnoseBadConversion(Sema &S, OverloadCandidate *Cand, unsigned I) {
   QualType FromTy = Conv.Bad.getFromType();
   QualType ToTy = Conv.Bad.getToType();
 
-  // Do some hand-waving analysis to see if the non-viability is due to a
+  // Do some hand-waving analysis to see if the non-viability is due
+  // to a qualifier mismatch.
   CanQualType CFromTy = S.Context.getCanonicalType(FromTy);
   CanQualType CToTy = S.Context.getCanonicalType(ToTy);
   if (CanQual<ReferenceType> RT = CToTy->getAs<ReferenceType>())
@@ -4464,6 +4465,20 @@ void DiagnoseBadConversion(Sema &S, OverloadCandidate *Cand, unsigned I) {
     return;
   }
 
+  // Diagnose references or pointers to incomplete types differently,
+  // since it's far from impossible that the incompleteness triggered
+  // the failure.
+  QualType TempFromTy = FromTy.getNonReferenceType();
+  if (const PointerType *PTy = TempFromTy->getAs<PointerType>())
+    TempFromTy = PTy->getPointeeType();
+  if (TempFromTy->isIncompleteType()) {
+    S.Diag(Fn->getLocation(), diag::note_ovl_candidate_bad_conv_incomplete)
+      << (unsigned) FnKind << FnDesc
+      << (FromExpr ? FromExpr->getSourceRange() : SourceRange())
+      << FromTy << ToTy << (unsigned) isObjectArgument << I+1;
+    return;
+  }
+
   // TODO: specialize more based on the kind of mismatch
   S.Diag(Fn->getLocation(), diag::note_ovl_candidate_bad_conv)
     << (unsigned) FnKind << FnDesc