Fix internal error on small array with negative lower bound

Ada supports arrays with negative indices, although the internal index type
is sizetype like in other languages, which is unsigned.  This means that
negative values are represented by very large numbers, which works with a
bit of care.  This plugs a small loophole in output_constructor_bitfield.

gcc/
	* varasm.cc (output_constructor_bitfield): Call tree_to_uhwi instead
	of tree_to_shwi on array indices.  Minor tweaks.

gcc/testsuite/
	* gnat.dg/specs/array6.ads: New test.

1 files changed, 14 insertions, 0 deletions

diff --git a/gcc/testsuite/gnat.dg/specs/array6.ads b/gcc/testsuite/gnat.dg/specs/array6.ads
new file mode 100644
index 0000000..72f8824
--- /dev/null
+++ b/gcc/testsuite/gnat.dg/specs/array6.ads
@@ -0,0 +1,14 @@
+-- { dg-do compile }
+
+package Array6 is 
+
+  type Range_Type is range -10 ..  10;
+  type Array_Type is array (Range_Type range <> ) of Short_Short_Integer;
+
+  type Record_Type is record 
+    A : Array_Type(-2..4);
+  end record ;
+
+  Rec : Record_Type := (A => (others => -1));
+
+end Array6;