[gdb/ada] Extend type equivalence test in ada_resolve_enum

When running test-case gdb.ada/local-enum.exp with target board debug-types, I
run into:
...
(gdb) print v1(three)^M
No name 'three' in enumeration type 'local__e1'^M
(gdb) FAIL: gdb.ada/local-enum.exp: print v1 element
...

The array V1 is of type A1 which is an array with index type E1, containing
"three" as enumerator:
...
  type E1 is (one, two, three);
  type A1 is array (E1) of Integer;
  V1 : A1 := (0, 1, 2);
...

There's also a type E2 that contains three as enumerator:
...
  type E2 is (three, four, five);
...

When doing "print v1(three)", it's the job of ada_resolve_enum to resolve
"three" to type E1 rather than type E2.

When using target board debug-types, the enums E1 and E2 are replicated in the
.debug_types section, and consequently in ada_resolve_enum the type
equivalence check using a pointer comparison fails:
...
  for (int i = 0; i < syms.size (); ++i)
    {
      /* We already know the name matches, so we're just looking for
	 an element of the correct enum type.  */
      if (ada_check_typedef (syms[i].symbol->type ()) == context_type)
 	return i;
    }
...

Fix this by also trying a structural comparison using
ada_identical_enum_types_p.

Tested on x86_64-linux.

Approved-By: Tom Tromey <tom@tromey.com>

PR ada/29335
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29335

1 files changed, 18 insertions, 3 deletions

diff --git a/gdb/ada-lang.c b/gdb/ada-lang.c
index 2e1b966..2496c09 100644
--- a/gdb/ada-lang.c
+++ b/gdb/ada-lang.c
@@ -204,6 +204,8 @@ static symbol_name_matcher_ftype *ada_get_symbol_name_matcher
 
 static int symbols_are_identical_enums
   (const std::vector<struct block_symbol> &syms);
+
+static int ada_identical_enum_types_p (struct type *type1, struct type *type2);
 
 
 /* The character set used for source files.  */
@@ -3801,11 +3803,24 @@ ada_resolve_enum (std::vector<struct block_symbol> &syms,
   gdb_assert (context_type->code () == TYPE_CODE_ENUM);
   context_type = ada_check_typedef (context_type);
 
+  /* We already know the name matches, so we're just looking for
+     an element of the correct enum type.  */
+  struct type *type1 = context_type;
+  for (int i = 0; i < syms.size (); ++i)
+    {
+      struct type *type2 = ada_check_typedef (syms[i].symbol->type ());
+      if (type1 == type2)
+	return i;
+    }
+
   for (int i = 0; i < syms.size (); ++i)
     {
-      /* We already know the name matches, so we're just looking for
-	 an element of the correct enum type.  */
-      if (ada_check_typedef (syms[i].symbol->type ()) == context_type)
+      struct type *type2 = ada_check_typedef (syms[i].symbol->type ());
+      if (type1->num_fields () != type2->num_fields ())
+	continue;
+      if (strcmp (type1->name (), type2->name ()) != 0)
+	continue;
+      if (ada_identical_enum_types_p (type1, type2))
 	return i;
     }