Reorganize this loop a bit so it doesn't crash for empty unions. Fixes

PR2419.

llvm-svn: 52060

clang/lib/CodeGen/CGExprConstant.cpp

@@ -213,13 +213,15 @@ public:
 
     // Find the field decl we're initializing, if any
     int FieldNo = 0; // Field no in RecordDecl
-    FieldDecl* curField;
-    do {
+    FieldDecl* curField = 0;
+    while (FieldNo < RD->getNumMembers()) {
       curField = RD->getMember(FieldNo);
       FieldNo++;
-    } while (!curField->getIdentifier() && FieldNo < RD->getNumMembers());
+      if (curField->getIdentifier())
+        break;
+    }
 
-    if (ILE->getNumInits() == 0 || !curField->getIdentifier())
+    if (!curField || !curField->getIdentifier() || ILE->getNumInits() == 0)
       return llvm::Constant::getNullValue(Ty);
 
     if (curField->isBitField()) {

clang/test/CodeGen/empty-union-init.c

@@ -0,0 +1,12 @@
+// RUN: clang -emit-llvm < %s -o -
+
+struct Mem {
+        union {
+        } u;
+};
+
+struct Mem *columnMem(){
+        static const struct Mem nullMem = { {} };
+}
+
+