Implement semantic analysis for transparent unions. This is largely

based on a patch from Anders Johnsen. CodeGen support is incomplete,
in that we do not properly coerce to the first field's type.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@70419 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 5 insertions, 1 deletions

diff --git a/lib/Sema/SemaOverload.cpp b/lib/Sema/SemaOverload.cpp
index f4b6598d9e..ab66939656 100644
--- a/lib/Sema/SemaOverload.cpp
+++ b/lib/Sema/SemaOverload.cpp
@@ -1888,9 +1888,13 @@ bool Sema::PerformCopyInitialization(Expr *&From, QualType ToType,
   if (!getLangOptions().CPlusPlus) {
     // In C, argument passing is the same as performing an assignment.
     QualType FromType = From->getType();
+    
     AssignConvertType ConvTy =
       CheckSingleAssignmentConstraints(ToType, From);
-
+    if (ConvTy != Compatible &&
+        CheckTransparentUnionArgumentConstraints(ToType, From) == Compatible)
+      ConvTy = Compatible;
+    
     return DiagnoseAssignmentResult(ConvTy, From->getLocStart(), ToType,
                                     FromType, From, Flavor);
   }