Remove TYPE_TAG_NAME

TYPE_TAG_NAME has been an occasional source of confusion and bugs.  It
seems to me that it is only useful for C and C++ -- but even there,
not so much, because at least with DWARF there doesn't seem to be any
way to wind up with a type where the name and the tag name are both
non-NULL and different.

So, this patch removes TYPE_TAG_NAME entirely.  This should save a
little memory, but more importantly, it simplifies this part of gdb.

A few minor test suite adjustments were needed.  In some situations
the new code does not yield identical output to the old code.

gdb/ChangeLog
2018-06-01  Tom Tromey  <tom@tromey.com>

	* valops.c (enum_constant_from_type, value_namespace_elt)
	(value_maybe_namespace_elt): Update.
	* valarith.c (find_size_for_pointer_math): Update.
	* target-descriptions.c (make_gdb_type): Update.
	* symmisc.c (print_symbol): Update.
	* stabsread.c (define_symbol, read_type)
	(complain_about_struct_wipeout, add_undefined_type)
	(cleanup_undefined_types_1): Update.
	* rust-lang.c (rust_tuple_type_p, rust_slice_type_p)
	(rust_range_type_p, val_print_struct, rust_print_struct_def)
	(rust_internal_print_type, rust_composite_type)
	(rust_evaluate_funcall, rust_evaluate_subexp)
	(rust_inclusive_range_type_p): Update.
	* python/py-type.c (typy_get_tag): Update.
	* p-typeprint.c (pascal_type_print_base): Update.
	* mdebugread.c (parse_symbol, parse_type): Update.
	* m2-typeprint.c (m2_long_set, m2_record_fields, m2_enum):
	Update.
	* guile/scm-type.c (gdbscm_type_tag): Update.
	* go-lang.c (sixg_string_p): Update.
	* gnu-v3-abi.c (build_gdb_vtable_type, build_std_type_info_type):
	Update.
	* gdbtypes.h (struct main_type) <tag_name>: Remove.
	(TYPE_TAG_NAME): Remove.
	* gdbtypes.c (type_name_no_tag): Simplify.
	(check_typedef, check_types_equal, recursive_dump_type)
	(copy_type_recursive, arch_composite_type): Update.
	* f-typeprint.c (f_type_print_base): Update.  Print "Type" prefix
	in summary mode when needed.
	* eval.c (evaluate_funcall): Update.
	* dwarf2read.c (fixup_go_packaging, read_structure_type)
	(process_structure_scope, read_enumeration_type)
	(read_namespace_type, read_module_type, determine_prefix): Update.
	* cp-support.c (inspect_type): Update.
	* coffread.c (process_coff_symbol, decode_base_type): Update.
	* c-varobj.c (c_is_path_expr_parent): Update.
	* c-typeprint.c (c_type_print_base_struct_union): Update.
	(c_type_print_base_1): Update.  Print struct/class/union/enum in
	summary when using C language.
	* ax-gdb.c (gen_struct_ref, gen_namespace_elt)
	(gen_maybe_namespace_elt): Update.
	* ada-lang.c (ada_type_name): Simplify.
	(empty_record, ada_template_to_fixed_record_type_1)
	(template_to_static_fixed_type)
	(to_record_with_fixed_variant_part, ada_check_typedef): Update.

gdb/testsuite/ChangeLog
2018-06-01  Tom Tromey  <tom@tromey.com>

	* gdb.xml/tdesc-regs.exp (load_description): Update expected
	results.
	* gdb.dwarf2/method-ptr.exp: Set language to C++.
	* gdb.dwarf2/member-ptr-forwardref.exp: Set language to C++.
	* gdb.cp/typeid.exp (do_typeid_tests): Update type_re.
	* gdb.base/maint.exp (maint_pass_if): Update.

1 files changed, 3 insertions, 18 deletions

diff --git a/gdb/gdbtypes.h b/gdb/gdbtypes.h
index 2a1ed609d18..1399b8efc13 100644
--- a/gdb/gdbtypes.h
+++ b/gdb/gdbtypes.h
@@ -721,26 +721,12 @@ struct main_type
 
   /* * Name of this type, or NULL if none.
 
-     This is used for printing only, except by poorly designed C++
-     code.  For looking up a name, look for a symbol in the
-     VAR_DOMAIN.  This is generally allocated in the objfile's
-     obstack.  However coffread.c uses malloc.  */
+     This is used for printing only.  For looking up a name, look for
+     a symbol in the VAR_DOMAIN.  This is generally allocated in the
+     objfile's obstack.  However coffread.c uses malloc.  */
 
   const char *name;
 
-  /* * Tag name for this type, or NULL if none.  This means that the
-     name of the type consists of a keyword followed by the tag name.
-     Which keyword is determined by the type code ("struct" for
-     TYPE_CODE_STRUCT, etc.).  As far as I know C/C++ are the only
-     languages with this feature.
-
-     This is used for printing only, except by poorly designed C++ code.
-     For looking up a name, look for a symbol in the STRUCT_DOMAIN.
-     One more legitimate use is that if TYPE_STUB is set, this is
-     the name to use to look for definitions in other files.  */
-
-  const char *tag_name;
-
   /* * Every type is now associated with a particular objfile, and the
      type is allocated on the objfile_obstack for that objfile.  One
      problem however, is that there are times when gdb allocates new
@@ -1293,7 +1279,6 @@ extern void allocate_gnat_aux_type (struct type *);
 #define TYPE_INSTANCE_FLAGS(thistype) (thistype)->instance_flags
 #define TYPE_MAIN_TYPE(thistype) (thistype)->main_type
 #define TYPE_NAME(thistype) TYPE_MAIN_TYPE(thistype)->name
-#define TYPE_TAG_NAME(type) TYPE_MAIN_TYPE(type)->tag_name
 #define TYPE_TARGET_TYPE(thistype) TYPE_MAIN_TYPE(thistype)->target_type
 #define TYPE_POINTER_TYPE(thistype) (thistype)->pointer_type
 #define TYPE_REFERENCE_TYPE(thistype) (thistype)->reference_type