From: Nuno Lopes <nunoplopes@sapo.pt>
Date: Thu, 15 Jan 2009 16:44:45 +0000 (+0000)
Subject: add support for initializing static vars with a cast to union (gcc extension)
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=6ed2ef8281e44fdd8f002d1cbe11668068d3e530;p=clang

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 468e95523c..07966399da 100644
--- 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 f23a34b11c..495b27cb1b 100644
--- 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 };