c: Diagnose compound literals with function type [PR108043]

Both C99 and latest C2X say that compound literal shall have an object type
(complete object type in the latter case) or array of unknown bound,
so complit with function type is invalid.  When the initializer had to be
non-empty for such case, we used to diagnose it as incorrect initializer,
but with (fntype){} now allowed we just ICE on it.

The following patch diagnoses that.

2022-12-19  Jakub Jelinek  <jakub@redhat.com>

	PR c/108043
	* c-parser.cc (c_parser_postfix_expression_after_paren_type): Diagnose
	compound literals with function type.

	* gcc.dg/pr108043.c: New test.
	* gcc.dg/c99-complit-2.c (foo): Adjust expected diagnostics for
	complit with function type.

diff --git a/gcc/c/c-parser.cc b/gcc/c/c-parser.cc
index 1bbb39f..7d6960f 100644 (file)
--- a/gcc/c/c-parser.cc
+++ b/gcc/c/c-parser.cc
@@ -10924,6 +10924,11 @@ c_parser_postfix_expression_after_paren_type (c_parser *parser,
       error_at (type_loc, "compound literal has variable size");
       type = error_mark_node;
     }
+  else if (TREE_CODE (type) == FUNCTION_TYPE)
+    {
+      error_at (type_loc, "compound literal has function type");
+      type = error_mark_node;
+    }
   if (constexpr_p && type != error_mark_node)
     {
       tree type_no_array = strip_array_types (type);

diff --git a/gcc/testsuite/gcc.dg/c99-complit-2.c b/gcc/testsuite/gcc.dg/c99-complit-2.c
index 8120ce8..5e1b5be 100644 (file)
--- a/gcc/testsuite/gcc.dg/c99-complit-2.c
+++ b/gcc/testsuite/gcc.dg/c99-complit-2.c
@@ -23,7 +23,7 @@ foo (int a)
   /* { dg-error "init" "incomplete union type" { target *-*-* } .-1 } */
   /* { dg-error "invalid use of undefined type" "" { target *-*-* } .-2 } */
   (void (void)) { 0 }; /* { dg-bogus "warning" "warning in place of error" } */
-  /* { dg-error "init" "function type" { target *-*-* } .-1 } */
+  /* { dg-error "compound literal has function type" "function type" { target *-*-* } .-1 } */
   (int [a]) { 1 }; /* { dg-bogus "warning" "warning in place of error" } */
   /* { dg-error "init|variable" "VLA type" { target *-*-* } .-1 } */
   /* Initializers must not attempt to initialize outside the object

diff --git a/gcc/testsuite/gcc.dg/pr108043.c b/gcc/testsuite/gcc.dg/pr108043.c
new file mode 100644 (file)
index 0000000..0cc0700
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr108043.c
@@ -0,0 +1,12 @@
+/* PR c/108043 */
+/* { dg-do compile } */
+/* { dg-options "" } */
+
+typedef void F (void);
+
+void
+foo (void)
+{
+  (F) {};              /* { dg-error "compound literal has function type" } */
+  (F) { foo };         /* { dg-error "compound literal has function type" } */
+}