[Ada] do not print arrays as array pointers

This patch enhances the debugger to distinguish between fat pointers
that represent either: array types, or array access types.  In the latter
case, the object/type is encoded as a typedef type pointing to the fat
pointer.

The first part of the change is to adjust ada_check_typedef to avoid
stripping the typedef layer when it points to a fat pointer.  The rest
of the patch is adjustments required in various places to deal with
the fact that the type is uses might now be a typedef.

gdb/ChangeLog:

        * ada-lang.h (ada_coerce_to_simple_array): Add declaration.
        * ada-lang.c (ada_typedef_target_type): New function.
        (desc_base_type): Add handling of fat pointer typedefs.
        (ada_coerce_to_simple_array): Make non-static.
        (decode_packed_array_bitsize): Add handling of fat pointer typedefs.
        Add assertion.
        (ada_template_to_fixed_record_type_1, ada_to_fixed_type)
        (ada_check_typedef): Add handling of fat pointer typedefs.
        (ada_evaluate_subexp) [OP_FUNCALL]: Likewise.
        * ada-typeprint.c (ada_print_type): Add handling of fat pointer
        typedefs.
        * ada-valprint.c (ada_val_print_1): Convert fat pointers that are not
        array accesses to simple arrays rather than simple array pointers.
        (ada_value_print): In the case of array descriptors, do not print
        the value type description unless it is an array access.

gdb/testsuite/ChangeLog:

        * gdb.ada/lang_switch.exp: Correct expected parameter value.

gdb/doc/ChangeLog:

        * gdb.texinfo (Ada Glitches): Remove paragraph describing the
        occasional case where the debugger prints an array address
        instead of the array itself.

1 files changed, 74 insertions, 5 deletions

diff --git a/gdb/ada-lang.c b/gdb/ada-lang.c
index 7ea01c7..3a5b10f 100644
--- a/gdb/ada-lang.c
+++ b/gdb/ada-lang.c
@@ -228,8 +228,6 @@ static int ada_resolve_function (struct ada_symbol_info *, int,
                                  struct value **, int, const char *,
                                  struct type *);
 
-static struct value *ada_coerce_to_simple_array (struct value *);
-
 static int ada_is_direct_array_type (struct type *);
 
 static void ada_language_arch_info (struct gdbarch *,
@@ -366,6 +364,41 @@ ada_inferior_exit (struct inferior *inf)
 
                         /* Utilities */
 
+/* If TYPE is a TYPE_CODE_TYPEDEF type, return the target type after
+   all typedef layers have been pealed.  Otherwise, return TYPE.
+
+   Normally, we really expect a typedef type to only have 1 typedef layer.
+   In other words, we really expect the target type of a typedef type to be
+   a non-typedef type.  This is particularly true for Ada units, because
+   the language does not have a typedef vs not-typedef distinction.
+   In that respect, the Ada compiler has been trying to eliminate as many
+   typedef definitions in the debugging information, since they generally
+   do not bring any extra information (we still use typedef under certain
+   circumstances related mostly to the GNAT encoding).
+
+   Unfortunately, we have seen situations where the debugging information
+   generated by the compiler leads to such multiple typedef layers.  For
+   instance, consider the following example with stabs:
+
+     .stabs  "pck__float_array___XUP:Tt(0,46)=s16P_ARRAY:(0,47)=[...]"[...]
+     .stabs  "pck__float_array___XUP:t(0,36)=(0,46)",128,0,6,0
+
+   This is an error in the debugging information which causes type
+   pck__float_array___XUP to be defined twice, and the second time,
+   it is defined as a typedef of a typedef.
+
+   This is on the fringe of legality as far as debugging information is
+   concerned, and certainly unexpected.  But it is easy to handle these
+   situations correctly, so we can afford to be lenient in this case.  */
+
+static struct type *
+ada_typedef_target_type (struct type *type)
+{
+  while (TYPE_CODE (type) == TYPE_CODE_TYPEDEF)
+    type = TYPE_TARGET_TYPE (type);
+  return type;
+}
+
 /* Given DECODED_NAME a string holding a symbol name in its
    decoded form (ie using the Ada dotted notation), returns
    its unqualified name.  */
@@ -1354,6 +1387,9 @@ desc_base_type (struct type *type)
   if (type == NULL)
     return NULL;
   type = ada_check_typedef (type);
+  if (TYPE_CODE (type) == TYPE_CODE_TYPEDEF)
+    type = ada_typedef_target_type (type);
+
   if (type != NULL
       && (TYPE_CODE (type) == TYPE_CODE_PTR
           || TYPE_CODE (type) == TYPE_CODE_REF))
@@ -1819,7 +1855,7 @@ ada_coerce_to_simple_array_ptr (struct value *arr)
    Otherwise, returns a standard GDB array describing ARR (which may
    be ARR itself if it already is in the proper form).  */
 
-static struct value *
+struct value *
 ada_coerce_to_simple_array (struct value *arr)
 {
   if (ada_is_array_descriptor_type (value_type (arr)))
@@ -1893,10 +1929,17 @@ ada_is_unconstrained_packed_array_type (struct type *type)
 static long
 decode_packed_array_bitsize (struct type *type)
 {
-  char *raw_name = ada_type_name (ada_check_typedef (type));
+  char *raw_name;
   char *tail;
   long bits;
 
+  /* Access to arrays implemented as fat pointers are encoded as a typedef
+     of the fat pointer type.  We need the name of the fat pointer type
+     to do the decoding, so strip the typedef layer.  */
+  if (TYPE_CODE (type) == TYPE_CODE_TYPEDEF)
+    type = ada_typedef_target_type (type);
+
+  raw_name = ada_type_name (ada_check_typedef (type));
   if (!raw_name)
     raw_name = ada_type_name (desc_base_type (type));
 
@@ -1904,6 +1947,7 @@ decode_packed_array_bitsize (struct type *type)
     return 0;
 
   tail = strstr (raw_name, "___XP");
+  gdb_assert (tail != NULL);
 
   if (sscanf (tail + sizeof ("___XP") - 1, "%ld", &bits) != 1)
     {
@@ -7146,6 +7190,15 @@ ada_template_to_fixed_record_type_1 (struct type *type,
         {
           struct type *field_type = TYPE_FIELD_TYPE (type, f);
 
+	  /* If our field is a typedef type (most likely a typedef of
+	     a fat pointer, encoding an array access), then we need to
+	     look at its target type to determine its characteristics.
+	     In particular, we would miscompute the field size if we took
+	     the size of the typedef (zero), instead of the size of
+	     the target type.  */
+	  if (TYPE_CODE (field_type) == TYPE_CODE_TYPEDEF)
+	    field_type = ada_typedef_target_type (field_type);
+
           TYPE_FIELD_TYPE (rtype, f) = field_type;
           TYPE_FIELD_NAME (rtype, f) = TYPE_FIELD_NAME (type, f);
           if (TYPE_FIELD_BITSIZE (type, f) > 0)
@@ -7703,7 +7756,7 @@ ada_to_fixed_type (struct type *type, const gdb_byte *valaddr,
       because we call check_typedef/ada_check_typedef pretty much everywhere.
       */
   if (TYPE_CODE (type) == TYPE_CODE_TYPEDEF
-      && (TYPE_MAIN_TYPE (TYPE_TARGET_TYPE (type))
+      && (TYPE_MAIN_TYPE (ada_typedef_target_type (type))
 	  == TYPE_MAIN_TYPE (fixed_type)))
     return type;
 
@@ -7789,6 +7842,15 @@ ada_check_typedef (struct type *type)
   if (type == NULL)
     return NULL;
 
+  /* If our type is a typedef type of a fat pointer, then we're done.
+     We don't want to strip the TYPE_CODE_TYPDEF layer, because this is
+     what allows us to distinguish between fat pointers that represent
+     array types, and fat pointers that represent array access types
+     (in both cases, the compiler implements them as fat pointers).  */
+  if (TYPE_CODE (type) == TYPE_CODE_TYPEDEF
+      && is_thick_pntr (ada_typedef_target_type (type)))
+    return type;
+
   CHECK_TYPEDEF (type);
   if (type == NULL || TYPE_CODE (type) != TYPE_CODE_ENUM
       || !TYPE_STUB (type)
@@ -9282,6 +9344,13 @@ ada_evaluate_subexp (struct type *expect_type, struct expression *exp,
         argvec[0] = value_addr (argvec[0]);
 
       type = ada_check_typedef (value_type (argvec[0]));
+
+      /* Ada allows us to implicitly dereference arrays when subscripting
+         them.  So, if this is an typedef (encoding use for array access
+	 types encoded as fat pointers), strip it now.  */
+      if (TYPE_CODE (type) == TYPE_CODE_TYPEDEF)
+	type = ada_typedef_target_type (type);
+
       if (TYPE_CODE (type) == TYPE_CODE_PTR)
         {
           switch (TYPE_CODE (ada_check_typedef (TYPE_TARGET_TYPE (type))))