================
@@ -0,0 +1,32 @@
+// RUN: %clang_cc1 -verify -std=c2y -pedantic %s
+// RUN: %clang_cc1 -verify=pre-c2y -std=c2y -Wpre-c2y-compat %s
+// RUN: %clang_cc1 -verify=ext -std=c23 -pedantic %s
+// expected-no-diagnostics
+
+/* WG14 N3409: Clang 21
+ * Slay Some Earthly Demons X
+ *
+ * Removes the requirement that an expression with type void cannot be used in
+ * any way. This was making it UB to use a void expression in a _Generic
+ * selection expression for no good reason, as well as making it UB to cast a
+ * void expression to void, etc.
+ */
+
+extern void x;
+void foo() {
+ // FIXME: this is technically an extension before C2y and should be diagnosed
+ // under -pedantic.
+ (void)(void)1;
+ // FIXME: same with this.
+ x;
+ _Generic(x, void: 1); /* pre-c2y-warning {{use of an incomplete type in
a '_Generic' association is incompatible with C standards before C2y; 'void' is
an incomplete type}}
+ ext-warning {{ISO C requires a complete type
in a '_Generic' association; 'void' is an incomplete type}}
+ */
+ _Generic(x, typeof(x): 1); /* pre-c2y-warning {{use of an incomplete type in
a '_Generic' association is incompatible with C standards before C2y; 'typeof
(x)' (aka 'void') is an incomplete type}}
+ ext-warning {{ISO C requires a complete type
in a '_Generic' association; 'typeof (x)' (aka 'void') is an incomplete type}}
+ */
+ (void)_Generic(void, default : 1); /* pre-c2y-warning {{passing a type
argument as the first operand to '_Generic' is incompatible with C standards
before C2y}}
+ ext-warning {{passing a type argument
as the first operand to '_Generic' is a C2y extension}}
+ */
----------------
Sirraide wrote:
What about `return x;` in this function (since it returns `void`)?
https://github.com/llvm/llvm-project/pull/130299
_______________________________________________
cfe-commits mailing list
cfe-commits@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
