PR25890: Fix incoherent error handling in PerformImplicitConversion and

CheckSingleAssignmentConstraints. These no longer produce ExprError() when they
have not emitted an error, and reliably inform the caller when they *have*
emitted an error.

This fixes some serious issues where we would fail to emit any diagnostic for
invalid code and then attempt to emit code for an invalid AST, and conversely
some issues where we would emit two diagnostics for the same problem.

llvm-svn: 283508

1 files changed, 4 insertions, 0 deletions

diff --git a/clang/lib/Sema/SemaExprCXX.cpp b/clang/lib/Sema/SemaExprCXX.cpp
index 8d20ac2a5d8..ad102f8d203 100644
--- a/clang/lib/Sema/SemaExprCXX.cpp
+++ b/clang/lib/Sema/SemaExprCXX.cpp
@@ -3320,6 +3320,10 @@ Sema::PerformImplicitConversion(Expr *From, QualType ToType,
     llvm_unreachable("Cannot perform an ellipsis conversion");
 
   case ImplicitConversionSequence::BadConversion:
+    bool Diagnosed =
+        DiagnoseAssignmentResult(Incompatible, From->getExprLoc(), ToType,
+                                 From->getType(), From, Action);
+    assert(Diagnosed && "failed to diagnose bad conversion"); (void)Diagnosed;
     return ExprError();
   }