Replace flag_strict_flex_arrays with DECL_NOT_FLEXARRAY in middle-end.

We should not directly check flag_strict_flex_arrays in the
middle end. Instead, check DECL_NOT_FLEXARRAY(array_field_decl) which is set
by C/C++ FEs according to -fstrict-flex-arrays and the corresponding
attribute attached to the array_field.

As a result, We will lose the LEVEL information of -fstrict-flex-arrays in
the middle end. -Wstrict-flex-arrays will not be able to issue such
information. update the testing cases accordingly.

gcc/ChangeLog:

	* attribs.cc (strict_flex_array_level_of): Move this function to ...
	* attribs.h (strict_flex_array_level_of): Remove the declaration.
	* gimple-array-bounds.cc (array_bounds_checker::check_array_ref):
	replace the referece to strict_flex_array_level_of with
	DECL_NOT_FLEXARRAY.
	* tree.cc (component_ref_size): Likewise.

gcc/c/ChangeLog:

	* c-decl.cc (strict_flex_array_level_of): ... here.

gcc/testsuite/ChangeLog:

	* gcc.dg/Warray-bounds-flex-arrays-1.c: Delete the level information
	from the message issued by -Wstrict-flex-arrays.
	* gcc.dg/Warray-bounds-flex-arrays-2.c: Likewise.
	* gcc.dg/Warray-bounds-flex-arrays-3.c: Likewise.
	* gcc.dg/Warray-bounds-flex-arrays-4.c: Likewise.
	* gcc.dg/Warray-bounds-flex-arrays-5.c: Likewise.
	* gcc.dg/Warray-bounds-flex-arrays-6.c: Likewise.
	* gcc.dg/Wstrict-flex-arrays-2.c: Likewise.
	* gcc.dg/Wstrict-flex-arrays-3.c: Likewise.
	* gcc.dg/Wstrict-flex-arrays.c: Likewise.

1 files changed, 7 insertions, 30 deletions

diff --git a/gcc/tree.cc b/gcc/tree.cc
index 78b64ee..7473912 100644
--- a/gcc/tree.cc
+++ b/gcc/tree.cc
@@ -13074,38 +13074,15 @@ component_ref_size (tree ref, special_array_member *sam /* = NULL */)
 	  || *sam == special_array_member::trail_n)
 	return memsize;
 
-      /* flag_strict_flex_arrays will control how to treat
-	 the trailing arrays as flexiable array members.  */
-
       tree afield_decl = TREE_OPERAND (ref, 1);
-      unsigned int strict_flex_array_level
-	= strict_flex_array_level_of (afield_decl);
-
-      switch (strict_flex_array_level)
-	{
-	  case 3:
-	    /* Treaing 0-length trailing arrays as normal array.  */
-	    if (*sam == special_array_member::trail_0)
-	      return size_zero_node;
-	    /* FALLTHROUGH.  */
-	  case 2:
-	    /* Treating 1-element trailing arrays as normal array.  */
-	    if (*sam == special_array_member::trail_1)
-	      return memsize;
-	    /* FALLTHROUGH.  */
-	  case 1:
-	    /* Treating 2-or-more elements trailing arrays as normal
-	       array.  */
-	    if (*sam == special_array_member::trail_n)
-	      return memsize;
-	    /* FALLTHROUGH.  */
-	  case 0:
-	    break;
-	  default:
-	    gcc_unreachable ();
-	}
+      gcc_assert (TREE_CODE (afield_decl) == FIELD_DECL);
+      /* if the trailing array is a not a flexible array member, treat it as
+	 a normal array.  */
+      if (DECL_NOT_FLEXARRAY (afield_decl)
+	  && *sam != special_array_member::int_0)
+	return memsize;
 
-	if (*sam == special_array_member::int_0)
+      if (*sam == special_array_member::int_0)
 	  memsize = NULL_TREE;
 
       /* For a reference to a flexible array member of a union