c: Fix up error-recovery on non-empty VLA initializers [PR109409]

On the following testcase we ICE, because after we emit the
variable-sized object may not be initialized except with an empty initializer
error we don't really reset the initializer to error_mark_node and then at
-Wformat checking time we ICE on seeing STRING_CST initializer for a VLA.

The following patch just arranges for error_mark_node to be returned after
the error diagnostics.

2023-04-27  Jakub Jelinek  <jakub@redhat.com>

	PR c/109409
	* c-parser.cc (c_parser_initializer): Move diagnostics about
	initialization of variable sized object with non-empty initializer
	after c_parser_expr_no_commas call and ret.set_error (); after it.

	* gcc.dg/pr109409.c: New test.

diff --git a/gcc/c/c-parser.cc b/gcc/c/c-parser.cc
index 9398c7a5271501332a1b8b09e26002ba33c0feb2..c9f06930e3a0d8c8a9139782539a412c94a15842 100644 (file)
--- a/gcc/c/c-parser.cc
+++ b/gcc/c/c-parser.cc
@@ -5677,11 +5677,14 @@ c_parser_initializer (c_parser *parser, tree decl)
     {
       struct c_expr ret;
       location_t loc = c_parser_peek_token (parser)->location;
-      if (decl != error_mark_node && C_DECL_VARIABLE_SIZE (decl))
-       error_at (loc,
-                 "variable-sized object may not be initialized except "
-                 "with an empty initializer");
       ret = c_parser_expr_no_commas (parser, NULL);
+      if (decl != error_mark_node && C_DECL_VARIABLE_SIZE (decl))
+       {
+         error_at (loc,
+                   "variable-sized object may not be initialized except "
+                   "with an empty initializer");
+         ret.set_error ();
+       }
       /* This is handled mostly by gimplify.cc, but we have to deal with
         not warning about int x = x; as it is a GCC extension to turn off
         this warning but only if warn_init_self is zero.  */

diff --git a/gcc/testsuite/gcc.dg/pr109409.c b/gcc/testsuite/gcc.dg/pr109409.c
new file mode 100644 (file)
index 0000000..097a511
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr109409.c
@@ -0,0 +1,10 @@
+/* PR c/109409 */
+/* { dg-do compile } */
+/* { dg-options "-Wall" } */
+
+void
+foo (int n)
+{
+  const char c[n] = "1";       /* { dg-error "variable-sized object may not be initialized except with an empty initializer" } */
+  __builtin_printf (c);
+}