c: ICE in build_counted_by_ref [PR116735]

When handling the counted_by attribute, if the corresponding field
doesn't exit, in additiion to issue error, we should also remove
the already added non-existing "counted_by" attribute from the
field_decl.

	PR c/116735

gcc/c/ChangeLog:

	* c-decl.cc (verify_counted_by_attribute): Remove the attribute
	when error.

gcc/testsuite/ChangeLog:

	* gcc.dg/flex-array-counted-by-9.c: New test.

2 files changed, 43 insertions, 14 deletions

diff --git a/gcc/c/c-decl.cc b/gcc/c/c-decl.cc
index aa7f69d..224c015 100644
--- a/gcc/c/c-decl.cc
+++ b/gcc/c/c-decl.cc
@@ -9502,14 +9502,17 @@ verify_counted_by_attribute (tree struct_type, tree field_decl)
 
   tree counted_by_field = lookup_field (struct_type, fieldname);
 
-  /* Error when the field is not found in the containing structure.  */
+  /* Error when the field is not found in the containing structure and
+     remove the corresponding counted_by attribute from the field_decl.  */
   if (!counted_by_field)
-    error_at (DECL_SOURCE_LOCATION (field_decl),
-	      "argument %qE to the %qE attribute is not a field declaration"
-	      " in the same structure as %qD", fieldname,
-	      (get_attribute_name (attr_counted_by)),
-	      field_decl);
-
+    {
+      error_at (DECL_SOURCE_LOCATION (field_decl),
+		"argument %qE to the %<counted_by%> attribute"
+		" is not a field declaration in the same structure"
+		" as %qD", fieldname, field_decl);
+      DECL_ATTRIBUTES (field_decl)
+	= remove_attribute ("counted_by", DECL_ATTRIBUTES (field_decl));
+    }
   else
   /* Error when the field is not with an integer type.  */
     {
@@ -9518,14 +9521,15 @@ verify_counted_by_attribute (tree struct_type, tree field_decl)
       tree real_field = TREE_VALUE (counted_by_field);
 
       if (!INTEGRAL_TYPE_P (TREE_TYPE (real_field)))
-	error_at (DECL_SOURCE_LOCATION (field_decl),
-		  "argument %qE to the %qE attribute is not a field declaration"
-		  " with an integer type", fieldname,
-		  (get_attribute_name (attr_counted_by)));
-
+	{
+	  error_at (DECL_SOURCE_LOCATION (field_decl),
+		    "argument %qE to the %<counted_by%> attribute"
+		    " is not a field declaration with an integer type",
+		    fieldname);
+	  DECL_ATTRIBUTES (field_decl)
+	    = remove_attribute ("counted_by", DECL_ATTRIBUTES (field_decl));
+	}
     }
-
-  return;
 }
 
 /* TYPE is a struct or union that we're applying may_alias to after the body is
diff --git a/gcc/testsuite/gcc.dg/flex-array-counted-by-9.c b/gcc/testsuite/gcc.dg/flex-array-counted-by-9.c
new file mode 100644
index 0000000..5c6fedd
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/flex-array-counted-by-9.c
@@ -0,0 +1,25 @@
+/* PR c/116735  */
+/* { dg-options "-std=c99" } */
+/* { dg-do compile } */
+
+struct foo {
+  int len;
+  int element[] __attribute__ ((__counted_by__ (lenx))); /* { dg-error "attribute is not a field declaration in the same structure as" } */
+};
+
+struct bar {
+  float count;
+  int array[] __attribute ((counted_by (count))); /* { dg-error "attribute is not a field declaration with an integer type" } */
+};
+
+int main ()
+{
+  struct foo *p = __builtin_malloc (sizeof (struct foo) + 3 * sizeof (int));
+  struct bar *q = __builtin_malloc (sizeof (struct bar) + 3 * sizeof (int));
+  p->len = 3;
+  p->element[0] = 17;
+  p->element[1] = 13;
+  q->array[0] = 13;
+  q->array[2] = 17;
+  return 0;
+}