[gcc r13-4797] c: Diagnose compound literals with function type [PR108043]

[Jakub Jelinek <jakub@gcc.gnu.org>]

https://gcc.gnu.org/g:4e4620d8c796af482b57b94932618d1f9d9af9f7

commit r13-4797-g4e4620d8c796af482b57b94932618d1f9d9af9f7
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Mon Dec 19 20:55:56 2022 +0100

    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:
---
 gcc/c/c-parser.cc                    |  5 +++++
 gcc/testsuite/gcc.dg/c99-complit-2.c |  2 +-
 gcc/testsuite/gcc.dg/pr108043.c      | 12 ++++++++++++
 3 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/gcc/c/c-parser.cc b/gcc/c/c-parser.cc
index 1bbb39f9b08..7d6960fffbb 100644
--- 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 8120ce8d988..5e1b5be8e28 100644
--- 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
index 00000000000..0cc0700f30a
--- /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" } */
+}