On Mon, Nov 7, 2011 at 7:54 AM, Dodji Seketeli <do...@redhat.com> wrote:
>> On 11/05/2011 07:36 PM, Dodji Seketeli wrote:
>> > +#define TYPE_DECL_NAMES_ALIAS_TEMPLATE_P(NODE) \
>>
>> This doesn't seem to be needed anymore.
>
> Removed, thanks.
>
>>
>> > +dump_alias_template_specialization (tree t, int flags)
>> > +{
>> > + gcc_assert (alias_template_specialization_p (t));
>> > +
>> > + if (CLASS_TYPE_P (t))
>> > + dump_aggr_type (t, flags);
>> > + else
>> > + {
>> > + tree name;
>> > + name = TYPE_IDENTIFIER (t);
>> > + pp_cxx_tree_identifier (cxx_pp, name);
>> > + dump_template_parms (TYPE_TEMPLATE_INFO (t),
>> > + /*primary=*/false,
>> > + flags & ~TFF_TEMPLATE_HEADER);
>> > + }
>>
>> Why do you treat class and non-class aliases differently? In both
>> cases I think we want alias specializations to be printed as
>> scope::name<args>. We don't want to print 'class' since such a
>> specialization cannot be used in an
>> elaborated-type-specifier.
>
> I didn't realize the elaborated-type-specifier case. Fixed now.
>
>>
>> > + if (alias_template_specialization_p (t))
>> > + {
>> > + dump_alias_template_specialization (t, flags);
>> > + return;
>> > + }
>> > + else if ((flags & TFF_CHASE_TYPEDEF)
>> > + || DECL_SELF_REFERENCE_P (decl)
>> > + || (!flag_pretty_templates
>> > + && DECL_LANG_SPECIFIC (decl) && DECL_TEMPLATE_INFO
>> > (decl)))
>> > t = strip_typedefs (t);
>>
>> The order of these two should be reversed. We want TFF_CHASE_TYPEDEF
>> and -fno-pretty-templates to strip alias-templates as well as
>> non-template typedefs.
>
> Fixed.
>
>>
>> > - /* If the next keyword is `namespace', we have a
>> > + /* If the next keyword is `namespace', we have either a
>> > namespace-alias-definition. */
>>
>> This change seems unintended.
>
> Oops, fixed. Thanks.
>
>>
>> > + if (!(type_decl != NULL_TREE
>> > + && TREE_CODE (type_decl) == TYPE_DECL
>> > + && TYPE_DECL_ALIAS_P (type_decl)
>> > + && DECL_TEMPLATE_INSTANTIATION (type_decl)))
>> > + cp_parser_simulate_error (parser);
>>
>> I think the TYPE_DECL_ALIAS_P and DECL_TEMPLATE_INSTANTIATION checks
>> should be an assert instead; at this point any TYPE_DECL we get should
>> satisfy those.
>
> I did that initially and it revealed that the assertion can be
> violated by erroneous input code, e.g (in the test
> g++.dg/cpp0x/vt-34055.C):
>
> template<typename...> struct B;
> template<typename...T> struct B<T&> // { dg-error "parameter packs|T" }
> {
> void foo();
> };
>
> Hence the recoverable error approach here. So I am now just asserting
> the DECL_TEMPLATE_INSTANTIATION when the TYPE_DECL is for an alias
> declaration. Is that better?
>
>>
>> > - || (TYPE_P (t) && TYPE_DECL_ALIAS_P (TYPE_NAME (t)))
>> > + || (TYPE_P (t)
>> > + && TYPE_NAME (t)
>> > + && TREE_CODE (TYPE_NAME (t)) == TYPE_DECL
>> > + && TYPE_DECL_ALIAS_P (TYPE_NAME (t)))
>>
>> In C++ I think a non-null TYPE_NAME is always a TYPE_DECL.
>
> I wonder why I added that check there. Removed now.
>
>>
>> >> Why not set r here, as for the other cases?
>> > Because I'd like to handle alias declarations even for cases handled
>> > by the other cases where, r is end up being NULL.
>>
>> Hmm. With this code we end up substituting into a non-template alias
>> declaration at file scope.
>
> Ah, I see.
>
>> I think if you check alias_template_specialization_p before checking
>> for class/function scope that should handle the cases you need.
>
> alias_template_specialization_p wouldn't work as we'd miss the case
> where we precisely want to build an instantiation from an alias
> template. So maybe the below is better?
>
> Thinking about that part of the code, I realized that the former patch
> didn't support (GNU extension) attributes so that part of the code
> wasn't tested enough. I have thus added new tests that are a slight
> modification of the g++.dg/cpp0x/ext/tmplattr*.C tests to use the
> alias-template syntax and exercise that part of the code.
>
> Bootstrapped and tested on x86_64-unknown-linux-gnu against trunk.
>
> From: Dodji Seketeli <do...@redhat.com>
> Date: Fri, 30 Sep 2011 12:52:52 +0200
> Subject: [PATCH] PR c++/45114 - Support alias templates
>
> gcc/cp/
>
> * cp-tree.h (TYPE_DECL_ALIAS_P, TYPE_ALIAS_P)
> (DECL_TYPE_TEMPLATE_P, DECL_ALIAS_TEMPLATE_P): New accessor
> macros.
> (TYPE_TEMPLATE_INFO): Get template info of an alias template
> specializations from its TYPE_DECL.
> (SET_TYPE_TEMPLATE_INFO): Set template info of alias template
> specializations into its TYPE_DECL.
> (DECL_CLASS_TEMPLATE_P): Re-write using the new
> DECL_TYPE_TEMPLATE_P.
> (enum cp_decl_spec): Add new ds_alias enumerator.
> (alias_type_or_template_p, alias_template_specialization_p):
> Declare new functions.
> * parser.c (cp_parser_alias_declaration): New static function.
> (cp_parser_check_decl_spec): Add "using" name for the `alias'
> declspec.
> (cp_parser_type_name): Update comment. Support simple-template-id
> representing alias template specializations in c++0x mode.
> (cp_parser_qualifying_entity): Update comment. Use
> cp_parser_type_name.
> (cp_parser_block_declaration): Handle alias-declaration in c++11.
> Update comment.
> (cp_parser_template_id): Handle specializations of alias
> templates.
> (cp_parser_member_declaration): Add alias-declaration production
> to comment. Support alias-declarations.
> (cp_parser_template_declaration_after_export): Handle alias
> templates in c++11.
> * decl.c (make_typename_type, make_unbound_class_template): Accept
> alias templates.
> (grokdeclarator): Set TYPE_DECL_ALIAS_P on alias
> declarations.
> * decl2.c (grokfield): Move template creation after setting up the
> TYPE_DECL of the alias, so that the TEMPLATE_DECL of the alias
> template actually carries the right type-id of the alias
> declaration.
> * pt.c (alias_type_or_template_p)
> (alias_template_specialization_p): Define new public functions.
> (maybe_process_partial_specialization): Reject partial
> specializations of alias templates.
> (primary_template_instantiation_p): Consider alias template
> instantiations.
> (push_template_decl_real): Assert that TYPE_DECLs of alias
> templates are different from those of class template. Store
> template info onto the TYPE_DECL of the alias template.
> (convert_template_argument): Strip aliases from template
> arguments.
> (lookup_template_class_1): Handle the creation of the
> specialization of an alias template.
> (tsubst_decl): Create a substituted copy of the TYPE_DECL of an
> member alias template.
> (tsubst): Handle substituting into the type of an alias template.
> Handle substituting UNBOUND_CLASS_TEMPLATE into
> BOUND_TEMPLATE_TEMPLATE_PARM.
> (do_type_instantiation): Better diagnostics when trying to
> explicitely instantiate a non-class template.
> * search.c (lookup_field_1, lookup_field_r): Support looking up
> alias templates.
> * semantics.c (finish_template_type): For instantiations of alias
> templates, return the TYPE_DECL of the actual alias and not the
> one of the aliased type.
> * error.c (dump_alias_template_specialization): New static
> function.
> (dump_type): Handle printing of alias templates and their
> specializations. templates.
> (dump_aggr_type): For specialization of alias templates, fetch
> arguments from the right place.
> (dump_decl): Print an alias-declaration like `using decl = type;'
> (dump_template_decl): Support printing of alias templates.
>
This caused:
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51036
--
H.J.
