Fix assertion when trying to represent Ada arrays in CodeView

The LF_ARRAY CodeView type represents a C- or C++-style array, which a
length known at compile time. We were crashing when using -gcodeview
with Ada (bug #121157), as the DW_AT_upper_bound value is not an
unsigned integer but something more complicated:

0x00000123:   DW_TAG_array_type
                DW_AT_type      (0x0000014d "character")
                DW_AT_sibling   (0x00000142)

0x0000012c:     DW_TAG_subrange_type
                  DW_AT_type    (0x00000142 "integer")
                  DW_AT_lower_bound     (DW_OP_push_object_address, DW_OP_plus_uconst 0x8, DW_OP_deref, DW_OP_deref_size 0x4)
                  DW_AT_upper_bound     (DW_OP_push_object_address, DW_OP_plus_uconst 0x8, DW_OP_deref, DW_OP_plus_uconst 0x4, DW_OP_deref_size 0x4)

It doesn't look like we can represent Ada arrays in CodeView, so return
0 in get_type_num_array_type so that they come through as an unknown
type.

gcc/
	* dwarf2codeview.cc (get_type_num_array_type): Don't try to
	encode non-C-style arrays.

1 files changed, 13 insertions, 0 deletions

diff --git a/gcc/dwarf2codeview.cc b/gcc/dwarf2codeview.cc
index d98b50c..154cd94 100644
--- a/gcc/dwarf2codeview.cc
+++ b/gcc/dwarf2codeview.cc
@@ -6748,10 +6748,23 @@ get_type_num_array_type (dw_die_ref type, bool in_struct)
   c = first_child;
   do
     {
+      dw_attr_node *upper_bound;
+
       c = dw_get_die_sib (c);
       if (dw_get_die_tag (c) != DW_TAG_subrange_type)
 	continue;
 
+      /* Check that each DW_TAG_subrange_type DIE has a DW_AT_upper_bound
+	 attribute that's an unsigned integer.  This is the case for C and
+	 C++, but not for other languages such as Ada.  */
+      upper_bound = get_AT (c, DW_AT_upper_bound);
+      if (!upper_bound)
+	return 0;
+
+      if (AT_class (upper_bound) != dw_val_class_unsigned_const
+	  && AT_class (upper_bound) != dw_val_class_unsigned_const_implicit)
+	return 0;
+
       dimensions++;
     }
   while (c != first_child);