-
-bar *fub();
-void test(bar &B1, const bar *B2) {
- // test various configurations of const
- const bar &B3 = B1;
- const bar *const B4 = B2;
-
- // test isa
- if (!isa<foo>(B1)) return;
- if (!isa<foo>(B2)) return;
- if (!isa<foo>(B3)) return;
- if (!isa<foo>(B4)) return;
-
- // test cast
- foo &F1 = cast<foo>(B1);
- const foo *F3 = cast<foo>(B2);
- const foo *F4 = cast<foo>(B2);
- const foo &F8 = cast<foo>(B3);
- const foo *F9 = cast<foo>(B4);
- foo *F10 = cast<foo>(fub());
-
- // test cast_or_null
- const foo *F11 = cast_or_null<foo>(B2);
- const foo *F12 = cast_or_null<foo>(B2);
- const foo *F13 = cast_or_null<foo>(B4);
- const foo *F14 = cast_or_null<foo>(fub()); // Shouldn't print.
-
- // These lines are errors...
- //foo *F20 = cast<foo>(B2); // Yields const foo*
- //foo &F21 = cast<foo>(B3); // Yields const foo&
- //foo *F22 = cast<foo>(B4); // Yields const foo*
- //foo &F23 = cast_or_null<foo>(B1);
- //const foo &F24 = cast_or_null<foo>(B3);
+// dyn_cast_or_null<X> - Functionally identical to dyn_cast, except that a null
+// value is accepted.
+//
+template <class X, class Y>
+LLVM_ATTRIBUTE_UNUSED_RESULT inline typename std::enable_if<
+ !is_simple_type<Y>::value, typename cast_retty<X, const Y>::ret_type>::type
+dyn_cast_or_null(const Y &Val) {
+ return (Val && isa<X>(Val)) ? cast<X>(Val) : nullptr;