stor-layout.c (layout_type): Make sure that an array of zero-sized element is zero-sized regardless of its...

* stor-layout.c (layout_type) <ARRAY_TYPE>: Make sure that an array
	of zero-sized element is zero-sized regardless of its extent.

From-SVN: r152415

gcc/ChangeLog

@@ -1,3 +1,8 @@
+2009-10-02  Eric Botcazou  <ebotcazou@adacore.com>
+
+	* stor-layout.c (layout_type) <ARRAY_TYPE>: Make sure that an array
+	of zero-sized element is zero-sized regardless of its extent.
+
 2009-10-02  Jakub Jelinek  <jakub@redhat.com>
 
 	PR debug/40521

gcc/stor-layout.c

@@ -1959,14 +1959,21 @@ layout_type (tree type)
 	    tree element_size = TYPE_SIZE (element);
 	    tree length;
 
+	    /* Make sure that an array of zero-sized element is zero-sized
+	       regardless of its extent.  */
+	    if (integer_zerop (element_size))
+	      length = size_zero_node;
+
 	    /* The initial subtraction should happen in the original type so
 	       that (possible) negative values are handled appropriately.  */
-	    length = size_binop (PLUS_EXPR, size_one_node,
-				 fold_convert (sizetype,
-					       fold_build2_loc (input_location,
-							    MINUS_EXPR,
-							    TREE_TYPE (lb),
-							    ub, lb)));
+	    else
+	      length
+		= size_binop (PLUS_EXPR, size_one_node,
+			      fold_convert (sizetype,
+					    fold_build2_loc (input_location,
+							     MINUS_EXPR,
+							     TREE_TYPE (lb),
+							     ub, lb)));
 
 	    TYPE_SIZE (type) = size_binop (MULT_EXPR, element_size,
 					   fold_convert (bitsizetype,

gcc/testsuite/ChangeLog

@@ -1,3 +1,8 @@
+2009-10-02  Eric Botcazou  <ebotcazou@adacore.com>
+
+	* gnat.dg/array10.adb: New test.
+	* gnat.dg/object_overflow.adb: Tweak.
+
 2009-10-02  Jack Howarth  <howarth@bromo.med.uc.edu>
 
         * gcc.dg/guality/guality.exp: Disable on darwin.

gcc/testsuite/gnat.dg/array10.adb

@@ -0,0 +1,25 @@
+-- { dg-do run }
+-- Verify that an array of non-aliased zero-sized element is zero-sized
+
+procedure Array10 is
+
+  type Rec is null record;
+
+  type Arr1 is array (1..8) of Rec;
+  type Arr2 is array (Long_Integer) of Rec;
+
+  R : Rec;
+  A1 : Arr1;
+  A2 : Arr2;
+
+begin
+  if Rec'Size /= 0 then
+    raise Program_Error;
+  end if;
+  if Arr1'Size /= 0 then
+    raise Program_Error;
+  end if;
+  if Arr2'Size /= 0 then
+    raise Program_Error;
+  end if;
+end;

gcc/testsuite/gnat.dg/object_overflow.adb

@@ -2,13 +2,12 @@
 
 procedure Object_Overflow is
 
-  type Rec is null record;
+  procedure Proc (x : Boolean) is begin null; end;
 
-  procedure Proc (x : Rec) is begin null; end;
-
-  type Arr is array(Long_Integer) of Rec;
+  type Arr is array(Long_Integer) of Boolean;
   Obj : Arr; -- { dg-warning "Storage_Error will be raised" }
 
 begin
+  Obj(1) := True;
   Proc (Obj(1));
 end;