PR2746: Implement GCC cast to union extension
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@62255 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/clang/Basic/DiagnosticKinds.def b/include/clang/Basic/DiagnosticKinds.def
index a9c6ea3..652c346 100644
--- a/include/clang/Basic/DiagnosticKinds.def
+++ b/include/clang/Basic/DiagnosticKinds.def
@@ -1427,6 +1427,10 @@
"C99 forbids conditional expressions with only one void side")
DIAG(ext_typecheck_cast_nonscalar, EXTENSION,
"C99 forbids casting nonscalar type %0 to the same type")
+DIAG(ext_typecheck_cast_to_union, EXTENSION,
+ "C99 forbids casts to union type")
+DIAG(err_typecheck_cast_to_union_no_type, ERROR,
+ "cast to union type from type %0 not present in union")
DIAG(err_typecheck_expect_scalar_operand, ERROR,
"operand of type %0 where arithmetic or pointer type is required")
DIAG(err_typecheck_cond_incompatible_operands, ERROR,
diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index 33d73bf..b8d58c1 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -1929,18 +1929,33 @@
} else if (castType->isDependentType() || castExpr->isTypeDependent()) {
// We can't check any more until template instantiation time.
} else if (!castType->isScalarType() && !castType->isVectorType()) {
- // GCC struct/union extension: allow cast to self.
- if (Context.getCanonicalType(castType).getUnqualifiedType() !=
- Context.getCanonicalType(castExpr->getType().getUnqualifiedType()) ||
- (!castType->isStructureType() && !castType->isUnionType())) {
+ if (Context.getCanonicalType(castType).getUnqualifiedType() ==
+ Context.getCanonicalType(castExpr->getType().getUnqualifiedType()) &&
+ (castType->isStructureType() || castType->isUnionType())) {
+ // GCC struct/union extension: allow cast to self.
+ Diag(TyR.getBegin(), diag::ext_typecheck_cast_nonscalar)
+ << castType << castExpr->getSourceRange();
+ } else if (castType->isUnionType()) {
+ // GCC cast to union extension
+ RecordDecl *RD = castType->getAsRecordType()->getDecl();
+ RecordDecl::field_iterator Field, FieldEnd;
+ for (Field = RD->field_begin(), FieldEnd = RD->field_end();
+ Field != FieldEnd; ++Field) {
+ if (Context.getCanonicalType(Field->getType()).getUnqualifiedType() ==
+ Context.getCanonicalType(castExpr->getType()).getUnqualifiedType()) {
+ Diag(TyR.getBegin(), diag::ext_typecheck_cast_to_union)
+ << castExpr->getSourceRange();
+ break;
+ }
+ }
+ if (Field == FieldEnd)
+ return Diag(TyR.getBegin(), diag::err_typecheck_cast_to_union_no_type)
+ << castExpr->getType() << castExpr->getSourceRange();
+ } else {
// Reject any other conversions to non-scalar types.
return Diag(TyR.getBegin(), diag::err_typecheck_cond_expect_scalar)
<< castType << castExpr->getSourceRange();
}
-
- // accept this, but emit an ext-warn.
- Diag(TyR.getBegin(), diag::ext_typecheck_cast_nonscalar)
- << castType << castExpr->getSourceRange();
} else if (!castExpr->getType()->isScalarType() &&
!castExpr->getType()->isVectorType()) {
return Diag(castExpr->getLocStart(),
diff --git a/test/Sema/cast-to-union.c b/test/Sema/cast-to-union.c
new file mode 100644
index 0000000..f23a34b
--- /dev/null
+++ b/test/Sema/cast-to-union.c
@@ -0,0 +1,9 @@
+// RUN: clang -fsyntax-only -verify -pedantic %s
+
+union u { int i; };
+void f(union u);
+
+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}}
+}