add support for initializing static vars with a cast to union (gcc extension)

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@62261 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index 468e95523c7988d8d6a858b58a37bfae8fb8175e..07966399da87827461fd883ac750fde3ac2277a9 100644 (file)
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -2228,7 +2228,14 @@ bool Sema::CheckForConstantInitializer(Expr *Init, QualType DclT) {
   // Allow block exprs at top level.
   if (Init->getType()->isBlockPointerType())
     return false;
-    
+
+  // GCC cast to union extension
+  // note: the validity of the cast expr is checked by CheckCastTypes()
+  if (CastExpr *C = dyn_cast<CastExpr>(Init)) {
+    QualType T = C->getType();
+    return T->isUnionType() && CheckForConstantInitializer(C->getSubExpr(), T);
+  }
+
   InitializerElementNotConstant(Init);
   return true;
 }

diff --git a/test/Sema/cast-to-union.c b/test/Sema/cast-to-union.c
index f23a34b11c54d516eb59cea87ce69ad942ba8f2a..495b27cb1bd2eae17a08aaccb8acd939946500a7 100644 (file)
--- a/test/Sema/cast-to-union.c
+++ b/test/Sema/cast-to-union.c
@@ -7,3 +7,13 @@ void test(int x) {
   f((union u)x); // expected-warning {{C99 forbids casts to union type}}
   f((union u)&x); // expected-error {{cast to union type from type 'int *' not present in union}}
 }
+
+union u w = (union u)2; // expected-warning {{C99 forbids casts to union type}}
+union u ww = (union u)1.0; // expected-error{{cast to union type from type 'double' not present in union}}
+union u x = 7; // expected-error{{incompatible type initializing 'int', expected 'union u'}}
+int i;
+union u zz = (union u)i; // expected-error{{initializer element is not a compile-time constant}}  expected-warning {{C99 forbids casts to union type}}
+
+struct s {int a, b;};
+struct s y = { 1, 5 };
+struct s z = (struct s){ 1, 5 };