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.

14 files changed, 68 insertions, 123 deletions

diff --git a/gcc/attribs.cc b/gcc/attribs.cc
index 49cb299..7db730c 100644
--- a/gcc/attribs.cc
+++ b/gcc/attribs.cc
@@ -2456,36 +2456,6 @@ init_attr_rdwr_indices (rdwr_map *rwm, tree attrs)
     }
 }
 
-/* Get the LEVEL of the strict_flex_array for the ARRAY_FIELD based on the
-   values of attribute strict_flex_array and the flag_strict_flex_arrays.  */
-unsigned int
-strict_flex_array_level_of (tree array_field)
-{
-  gcc_assert (TREE_CODE (array_field) == FIELD_DECL);
-  unsigned int strict_flex_array_level = flag_strict_flex_arrays;
-
-  tree attr_strict_flex_array
-    = lookup_attribute ("strict_flex_array", DECL_ATTRIBUTES (array_field));
-  /* If there is a strict_flex_array attribute attached to the field,
-     override the flag_strict_flex_arrays.  */
-  if (attr_strict_flex_array)
-    {
-      /* Get the value of the level first from the attribute.  */
-      unsigned HOST_WIDE_INT attr_strict_flex_array_level = 0;
-      gcc_assert (TREE_VALUE (attr_strict_flex_array) != NULL_TREE);
-      attr_strict_flex_array = TREE_VALUE (attr_strict_flex_array);
-      gcc_assert (TREE_VALUE (attr_strict_flex_array) != NULL_TREE);
-      attr_strict_flex_array = TREE_VALUE (attr_strict_flex_array);
-      gcc_assert (tree_fits_uhwi_p (attr_strict_flex_array));
-      attr_strict_flex_array_level = tree_to_uhwi (attr_strict_flex_array);
-
-      /* The attribute has higher priority than flag_struct_flex_array.  */
-      strict_flex_array_level = attr_strict_flex_array_level;
-    }
-  return strict_flex_array_level;
-}
-
-
 /* Return the access specification for a function parameter PARM
    or null if the current function has no such specification.  */
 
diff --git a/gcc/attribs.h b/gcc/attribs.h
index e7540f7..140e70b 100644
--- a/gcc/attribs.h
+++ b/gcc/attribs.h
@@ -398,6 +398,4 @@ extern void init_attr_rdwr_indices (rdwr_map *, tree);
 extern attr_access *get_parm_access (rdwr_map &, tree,
 				     tree = current_function_decl);
 
-extern unsigned int strict_flex_array_level_of (tree);
-
 #endif // GCC_ATTRIBS_H
diff --git a/gcc/c/c-decl.cc b/gcc/c/c-decl.cc
index d76ffb3..38647c1 100644
--- a/gcc/c/c-decl.cc
+++ b/gcc/c/c-decl.cc
@@ -9047,6 +9047,34 @@ finish_incomplete_vars (tree incomplete_vars, bool toplevel)
     }
 }
 
+/* Get the LEVEL of the strict_flex_array for the ARRAY_FIELD based on the
+   values of attribute strict_flex_array and the flag_strict_flex_arrays.  */
+static unsigned int
+strict_flex_array_level_of (tree array_field)
+{
+  gcc_assert (TREE_CODE (array_field) == FIELD_DECL);
+  unsigned int strict_flex_array_level = flag_strict_flex_arrays;
+
+  tree attr_strict_flex_array
+    = lookup_attribute ("strict_flex_array", DECL_ATTRIBUTES (array_field));
+  /* If there is a strict_flex_array attribute attached to the field,
+     override the flag_strict_flex_arrays.  */
+  if (attr_strict_flex_array)
+    {
+      /* Get the value of the level first from the attribute.  */
+      unsigned HOST_WIDE_INT attr_strict_flex_array_level = 0;
+      gcc_assert (TREE_VALUE (attr_strict_flex_array) != NULL_TREE);
+      attr_strict_flex_array = TREE_VALUE (attr_strict_flex_array);
+      gcc_assert (TREE_VALUE (attr_strict_flex_array) != NULL_TREE);
+      attr_strict_flex_array = TREE_VALUE (attr_strict_flex_array);
+      gcc_assert (tree_fits_uhwi_p (attr_strict_flex_array));
+      attr_strict_flex_array_level = tree_to_uhwi (attr_strict_flex_array);
+
+      /* The attribute has higher priority than flag_struct_flex_array.  */
+      strict_flex_array_level = attr_strict_flex_array_level;
+    }
+  return strict_flex_array_level;
+}
 
 /* Determine whether the FIELD_DECL X is a flexible array member according to
    the following info:
diff --git a/gcc/gimple-array-bounds.cc b/gcc/gimple-array-bounds.cc
index 116200a..66fd46e 100644
--- a/gcc/gimple-array-bounds.cc
+++ b/gcc/gimple-array-bounds.cc
@@ -350,18 +350,14 @@ array_bounds_checker::check_array_ref (location_t location, tree ref,
 
   /* Set to the type of the special array member for a COMPONENT_REF.  */
   special_array_member sam{ };
-
+  tree afield_decl = NULL_TREE;
   tree arg = TREE_OPERAND (ref, 0);
-  const bool compref = TREE_CODE (arg) == COMPONENT_REF;
-  unsigned int strict_flex_array_level = flag_strict_flex_arrays;
 
-  if (compref)
+  if (TREE_CODE (arg) == COMPONENT_REF)
     {
       /* Try to determine special array member type for this COMPONENT_REF.  */
       sam = component_ref_sam_type (arg);
-      /* Get the level of strict_flex_array for this array field.  */
-      tree afield_decl = TREE_OPERAND (arg, 1);
-      strict_flex_array_level = strict_flex_array_level_of (afield_decl);
+      afield_decl = TREE_OPERAND (arg, 1);
     }
 
   get_up_bounds_for_array_ref (ref, &decl, &up_bound, &up_bound_p1);
@@ -412,39 +408,15 @@ array_bounds_checker::check_array_ref (location_t location, tree ref,
 
       /* issue warnings for -Wstrict-flex-arrays according to the level of
 	 flag_strict_flex_arrays.  */
-      if (out_of_bound && warn_strict_flex_arrays)
-      switch (strict_flex_array_level)
-	{
-	  case 3:
-	    /* Issue additional warnings for trailing arrays [0].  */
-	    if (sam == special_array_member::trail_0)
+      if ((out_of_bound && warn_strict_flex_arrays)
+	  && (((sam == special_array_member::trail_0)
+		|| (sam == special_array_member::trail_1)
+		|| (sam == special_array_member::trail_n))
+	      && DECL_NOT_FLEXARRAY (afield_decl)))
 	      warned = warning_at (location, OPT_Wstrict_flex_arrays,
 				   "trailing array %qT should not be used as "
-				   "a flexible array member for level 3",
+				   "a flexible array member",
 				   artype);
-	    /* FALLTHROUGH.  */
-	  case 2:
-	    /* Issue additional warnings for trailing arrays [1].  */
-	    if (sam == special_array_member::trail_1)
-	      warned = warning_at (location, OPT_Wstrict_flex_arrays,
-				   "trailing array %qT should not be used as "
-				   "a flexible array member for level 2 and "
-				   "above", artype);
-	    /* FALLTHROUGH.  */
-	  case 1:
-	    /* Issue warnings for trailing arrays [n].  */
-	    if (sam == special_array_member::trail_n)
-	      warned = warning_at (location, OPT_Wstrict_flex_arrays,
-				   "trailing array %qT should not be used as "
-				   "a flexible array member for level 1 and "
-				   "above", artype);
-	    break;
-	  case 0:
-	    /* Do nothing.  */
-	    break;
-	  default:
-	    gcc_unreachable ();
-	}
 
       /* Avoid more warnings when checking more significant subscripts
 	 of the same expression.  */
diff --git a/gcc/testsuite/gcc.dg/Warray-bounds-flex-arrays-1.c b/gcc/testsuite/gcc.dg/Warray-bounds-flex-arrays-1.c
index 65c9fec..fd2aacf 100644
--- a/gcc/testsuite/gcc.dg/Warray-bounds-flex-arrays-1.c
+++ b/gcc/testsuite/gcc.dg/Warray-bounds-flex-arrays-1.c
@@ -32,7 +32,7 @@ void __attribute__((__noinline__)) stuff(
     struct trailing_array_4 *trailing_flex)
 {
     normal->c[5] = 5; 	/*{ dg-warning "array subscript 5 is above array bounds of" } */
-    			/*{ dg-warning "should not be used as a flexible array member for level 1 and above" "" { target *-*-* } .-1 } */
+    			/*{ dg-warning "should not be used as a flexible array member" "" { target *-*-* } .-1 } */
     trailing_1->c[2] = 2; /* { dg-bogus "array subscript " } */
     trailing_0->c[1] = 1; /* { dg-bogus "array subscript " } */
     trailing_flex->c[10] = 10; /* { dg-bogus "array subscript " } */
diff --git a/gcc/testsuite/gcc.dg/Warray-bounds-flex-arrays-2.c b/gcc/testsuite/gcc.dg/Warray-bounds-flex-arrays-2.c
index 2b5a895..55b7535 100644
--- a/gcc/testsuite/gcc.dg/Warray-bounds-flex-arrays-2.c
+++ b/gcc/testsuite/gcc.dg/Warray-bounds-flex-arrays-2.c
@@ -32,9 +32,9 @@ void __attribute__((__noinline__)) stuff(
     struct trailing_array_4 *trailing_flex)
 {
     normal->c[5] = 5; 	/*{ dg-warning "array subscript 5 is above array bounds of" } */
-    			/*{ dg-warning "should not be used as a flexible array member for level 1 and above" "" { target *-*-* } .-1 } */
+    			/*{ dg-warning "should not be used as a flexible array member" "" { target *-*-* } .-1 } */
     trailing_1->c[2] = 2; /* { dg-warning "array subscript 2 is above array bounds of"  } */
-    			  /* { dg-warning "should not be used as a flexible array member for level 2 and above" "" { target *-*-* } .-1 } */
+    			  /* { dg-warning "should not be used as a flexible array member" "" { target *-*-* } .-1 } */
     trailing_0->c[1] = 1; /* { dg-bogus "array subscript " } */
     trailing_flex->c[10] = 10; /* { dg-bogus "array subscript " } */
 
diff --git a/gcc/testsuite/gcc.dg/Warray-bounds-flex-arrays-3.c b/gcc/testsuite/gcc.dg/Warray-bounds-flex-arrays-3.c
index 25b903f..abdf8f1 100644
--- a/gcc/testsuite/gcc.dg/Warray-bounds-flex-arrays-3.c
+++ b/gcc/testsuite/gcc.dg/Warray-bounds-flex-arrays-3.c
@@ -32,11 +32,11 @@ void __attribute__((__noinline__)) stuff(
     struct trailing_array_4 *trailing_flex)
 {
     normal->c[5] = 5; 	/*{ dg-warning "array subscript 5 is above array bounds of" } */ 
-    			/*{ dg-warning "should not be used as a flexible array member for level 1 and above" "" { target *-*-* } .-1 } */
+    			/*{ dg-warning "should not be used as a flexible array member" "" { target *-*-* } .-1 } */
     trailing_1->c[2] = 2; /*{ dg-warning "array subscript 2 is above array bounds of" } */ 
-    			  /* { dg-warning "should not be used as a flexible array member for level 2 and above" "" { target *-*-* } .-1 } */
+    			  /* { dg-warning "should not be used as a flexible array member" "" { target *-*-* } .-1 } */
     trailing_0->c[1] = 1; /*{ dg-warning "array subscript 1 is outside array bounds of" } */ 
-    			  /* { dg-warning "should not be used as a flexible array member for level 3" "" { target *-*-* } .-1 } */
+    			  /* { dg-warning "should not be used as a flexible array member" "" { target *-*-* } .-1 } */
     trailing_flex->c[10] = 10; /* { dg-bogus "array subscript" } */
 
 }
diff --git a/gcc/testsuite/gcc.dg/Warray-bounds-flex-arrays-4.c b/gcc/testsuite/gcc.dg/Warray-bounds-flex-arrays-4.c
index 5fc500a..82b38ff 100644
--- a/gcc/testsuite/gcc.dg/Warray-bounds-flex-arrays-4.c
+++ b/gcc/testsuite/gcc.dg/Warray-bounds-flex-arrays-4.c
@@ -32,7 +32,7 @@ void __attribute__((__noinline__)) stuff(
     struct trailing_array_4 *trailing_flex)
 {
     normal->c[5] = 5; 	/*{ dg-warning "array subscript 5 is above array bounds of" } */
-    			/*{ dg-warning "should not be used as a flexible array member for level 1 and above" "" { target *-*-* } .-1 } */
+    			/*{ dg-warning "should not be used as a flexible array member" "" { target *-*-* } .-1 } */
     trailing_1->c[2] = 2; /* { dg-bogus "array subscript " } */
     trailing_0->c[1] = 1; /* { dg-bogus "array subscript " } */
     trailing_flex->c[10] = 10; /* { dg-bogus "array subscript " } */
diff --git a/gcc/testsuite/gcc.dg/Warray-bounds-flex-arrays-5.c b/gcc/testsuite/gcc.dg/Warray-bounds-flex-arrays-5.c
index 30bb4ca..dca0228 100644
--- a/gcc/testsuite/gcc.dg/Warray-bounds-flex-arrays-5.c
+++ b/gcc/testsuite/gcc.dg/Warray-bounds-flex-arrays-5.c
@@ -32,9 +32,9 @@ void __attribute__((__noinline__)) stuff(
     struct trailing_array_4 *trailing_flex)
 {
     normal->c[5] = 5;   /*{ dg-warning "array subscript 5 is above array bounds of" } */
-    			/*{ dg-warning "should not be used as a flexible array member for level 1 and above" "" { target *-*-* } .-1 } */
+    			/*{ dg-warning "should not be used as a flexible array member" "" { target *-*-* } .-1 } */
     trailing_1->c[2] = 2; /*{ dg-warning "array subscript 2 is above array bounds of" } */
-    			  /* { dg-warning "should not be used as a flexible array member for level 2 and above" "" { target *-*-* } .-1 } */
+    			  /* { dg-warning "should not be used as a flexible array member" "" { target *-*-* } .-1 } */
     trailing_0->c[1] = 1; /* { dg-bogus "array subscript " } */
     trailing_flex->c[10] = 10; /* { dg-bogus "array subscript " } */
 
diff --git a/gcc/testsuite/gcc.dg/Warray-bounds-flex-arrays-6.c b/gcc/testsuite/gcc.dg/Warray-bounds-flex-arrays-6.c
index e847a44..fc9f73b 100644
--- a/gcc/testsuite/gcc.dg/Warray-bounds-flex-arrays-6.c
+++ b/gcc/testsuite/gcc.dg/Warray-bounds-flex-arrays-6.c
@@ -32,11 +32,11 @@ void __attribute__((__noinline__)) stuff(
     struct trailing_array_4 *trailing_flex)
 {
     normal->c[5] = 5; 	/*{ dg-warning "array subscript 5 is above array bounds of" } */ 
-    			/*{ dg-warning "should not be used as a flexible array member for level 1 and above" "" { target *-*-* } .-1 } */
+    			/*{ dg-warning "should not be used as a flexible array member" "" { target *-*-* } .-1 } */
     trailing_1->c[2] = 2; /*{ dg-warning "array subscript 2 is above array bounds of" } */
-    			  /* { dg-warning "should not be used as a flexible array member for level 2 and above" "" { target *-*-* } .-1 } */
+    			  /* { dg-warning "should not be used as a flexible array member" "" { target *-*-* } .-1 } */
     trailing_0->c[1] = 1; /*{ dg-warning "array subscript 1 is outside array bounds of" } */
-    			  /* { dg-warning "should not be used as a flexible array member for level 3" "" { target *-*-* } .-1 } */
+    			  /* { dg-warning "should not be used as a flexible array member" "" { target *-*-* } .-1 } */
     trailing_flex->c[10] = 10; /* { dg-bogus "array subscript " } */
 
 }
diff --git a/gcc/testsuite/gcc.dg/Wstrict-flex-arrays-2.c b/gcc/testsuite/gcc.dg/Wstrict-flex-arrays-2.c
index 2e241f9..befc604 100644
--- a/gcc/testsuite/gcc.dg/Wstrict-flex-arrays-2.c
+++ b/gcc/testsuite/gcc.dg/Wstrict-flex-arrays-2.c
@@ -31,9 +31,9 @@ void __attribute__((__noinline__)) stuff(
     struct trailing_array_3 *trailing_0,
     struct trailing_array_4 *trailing_flex)
 {
-    normal->c[5] = 5; 	/*{ dg-warning "should not be used as a flexible array member for level 1 and above" } */
-    trailing_1->c[2] = 2; /* { dg-warning "should not be used as a flexible array member for level 2 and above" } */
-    trailing_0->c[1] = 1; /* { dg-bogus "should not be used as a flexible array member for level 2 and above" } */
-    trailing_flex->c[10] = 10; /* { dg-bogus "should not be used as a flexible array member for level 2 and above" } */
+    normal->c[5] = 5; 	/*{ dg-warning "should not be used as a flexible array member" } */
+    trailing_1->c[2] = 2; /* { dg-warning "should not be used as a flexible array member" } */
+    trailing_0->c[1] = 1; /* { dg-bogus "should not be used as a flexible array member" } */
+    trailing_flex->c[10] = 10; /* { dg-bogus "should not be used as a flexible array member" } */
 
 }
diff --git a/gcc/testsuite/gcc.dg/Wstrict-flex-arrays-3.c b/gcc/testsuite/gcc.dg/Wstrict-flex-arrays-3.c
index 97eb65b..cc37a09 100644
--- a/gcc/testsuite/gcc.dg/Wstrict-flex-arrays-3.c
+++ b/gcc/testsuite/gcc.dg/Wstrict-flex-arrays-3.c
@@ -31,9 +31,9 @@ void __attribute__((__noinline__)) stuff(
     struct trailing_array_3 *trailing_0,
     struct trailing_array_4 *trailing_flex)
 {
-    normal->c[5] = 5; 	/*{ dg-warning "should not be used as a flexible array member for level 1 and above" } */
-    trailing_1->c[2] = 2; /* { dg-warning "should not be used as a flexible array member for level 2 and above" } */
-    trailing_0->c[1] = 1; /* { dg-warning "should not be used as a flexible array member for level 3" } */
-    trailing_flex->c[10] = 10; /* { dg-bogus "should not be used as a flexible array member for level 3" } */
+    normal->c[5] = 5; 	/*{ dg-warning "should not be used as a flexible array member" } */
+    trailing_1->c[2] = 2; /* { dg-warning "should not be used as a flexible array member" } */
+    trailing_0->c[1] = 1; /* { dg-warning "should not be used as a flexible array member" } */
+    trailing_flex->c[10] = 10; /* { dg-bogus "should not be used as a flexible array member" } */
 
 }
diff --git a/gcc/testsuite/gcc.dg/Wstrict-flex-arrays.c b/gcc/testsuite/gcc.dg/Wstrict-flex-arrays.c
index 110fdc7..735b23a 100644
--- a/gcc/testsuite/gcc.dg/Wstrict-flex-arrays.c
+++ b/gcc/testsuite/gcc.dg/Wstrict-flex-arrays.c
@@ -31,9 +31,9 @@ void __attribute__((__noinline__)) stuff(
     struct trailing_array_3 *trailing_0,
     struct trailing_array_4 *trailing_flex)
 {
-    normal->c[5] = 5; 	/*{ dg-warning "should not be used as a flexible array member for level 1 and above" } */
-    trailing_1->c[2] = 2; /* { dg-bogus "should not be used as a flexible array member for level 1 and above" } */
-    trailing_0->c[1] = 1; /* { dg-bogus "should not be used as a flexible array member for level 1 and above" } */
-    trailing_flex->c[10] = 10; /* { dg-bogus "should not be used as a flexible array member for level 1 and above" } */
+    normal->c[5] = 5; 	/*{ dg-warning "should not be used as a flexible array member" } */
+    trailing_1->c[2] = 2; /* { dg-bogus "should not be used as a flexible array member" } */
+    trailing_0->c[1] = 1; /* { dg-bogus "should not be used as a flexible array member" } */
+    trailing_flex->c[10] = 10; /* { dg-bogus "should not be used as a flexible array member" } */
 
 }
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