| Summary: | T const assumed to be compatible with int (A::*) (void) const | ||
|---|---|---|---|
| Product: | gcc | Reporter: | Dodji Seketeli <dodji> |
| Component: | libstdc++ | Assignee: | Jason Merrill <jason> |
| Status: | RESOLVED FIXED | ||
| Severity: | normal | CC: | dodji, fang, gcc-bugs, jason, paolo |
| Priority: | P3 | ||
| Version: | unknown | ||
| Target Milestone: | 4.4.0 | ||
| Host: | Target: | ||
| Build: | Known to work: | ||
| Known to fail: | Last reconfirmed: | ||
| Bug Depends on: | |||
| Bug Blocks: | 37806 | ||
| Attachments: |
Fix for is_member_function_pointer and GCC
New fix that adds function cv-qual handling to is_function, and fixes compiler to allow that |
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Created attachment 17367 [details]
Fix for is_member_function_pointer and GCC
Rather, the test should pass, but we need to fix is_member_function_pointer so it will still pass without the GCC bug. Patch attached.
I have filed bug http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39321 that describes the gcc bug. It also has a patch that should fix it. The discussion of Core issue 547 (http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#547) suggests that we ought to be able to write partial specializations of is_function that can deal with function cv-quals. Created attachment 17389 [details]
New fix that adds function cv-qual handling to is_function, and fixes compiler to allow that
Here's a fix along those lines.
Hi. I'll try to catch up as soon as possible on the details of (the v3 bits of) this issue, but first blush it seems real strange to me that we cannot implement anymore the is_member_pointer trait as an OR of the is_member_object_pointer and the is_member_function_pointer traits. Can I have a quick "executive report" about the rationale of this part of the proposed fix? Subject: Re: T const assumed to be compatible with int
(A::*) (void) const
paolo dot carlini at oracle dot com wrote:
> it seems real strange to me that we cannot
> implement anymore the is_member_pointer trait as an OR of the
> is_member_object_pointer and the is_member_function_pointer traits.
We can still implement it that way; that part of the patch is just an
optimization. I'm can drop it if you prefer.
Thanks, Jason, now I see it. Then I'm Ok with the patch as-is. Jason, are you going to commit the is_member-2.patch? I was planning to wait until 4.4 branches. If you'd rather have it in 4.4, I can commit it now. (In reply to comment #9) > I was planning to wait until 4.4 branches. If you'd rather have it in 4.4, I > can commit it now. Well, if you ask me, yes, I would like to see it in 4.4. Thanks in advance. Subject: Bug 39310 Author: jason Date: Tue Mar 31 18:31:17 2009 New Revision: 145365 URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=145365 Log: PR c++/37806 * typeck.c (cp_apply_type_quals_to_decl): Don't apply any quals to a typedef. * tree.c (cp_build_qualified_type_real): Don't apply restrict to a function type. * decl.h (enum decl_context): Add TEMPLATE_TYPE_ARG. * decl.c (groktypename): Add is_template_arg parameter. (grokdeclarator): Allow function cv-quals on a template type arg. * parser.c (cp_parser_new_type_id, cp_parser_type_id): Add is_template_arg argument in calls to groktypename. * cp-tree.h: Adjust prototype. * error.c (dump_type_prefix, dump_type_suffix): Fix plain FUNCTION_TYPE printing. PR libstdc++/39310 * include/tr1_impl/type_traits (is_function): Add partial specializations with function cv-quals. (__is_function_helper): Remove. (is_member_pointer): Don't define in terms of is_member_*_pointer. Modified: trunk/gcc/cp/ChangeLog trunk/gcc/cp/cp-tree.h trunk/gcc/cp/decl.c trunk/gcc/cp/decl.h trunk/gcc/cp/error.c trunk/gcc/cp/parser.c trunk/gcc/cp/tree.c trunk/gcc/cp/typeck.c trunk/gcc/testsuite/g++.dg/template/qualttp20.C trunk/libstdc++-v3/ChangeLog trunk/libstdc++-v3/include/tr1_impl/type_traits Fixed in trunk (gcc 4.5). Subject: Bug 39310 Author: jason Date: Tue Apr 7 04:38:10 2009 New Revision: 145648 URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=145648 Log: * decl.c (grokdeclarator): Reject pointer to qualified function type. PR c++/37806, core issue 547 * typeck.c (cp_apply_type_quals_to_decl): Don't apply any quals to a typedef. * tree.c (cp_build_qualified_type_real): Don't apply restrict to a function type. * decl.h (enum decl_context): Add TEMPLATE_TYPE_ARG. * decl.c (groktypename): Add is_template_arg parameter. (grokdeclarator): Allow function cv-quals on a template type arg. * parser.c (cp_parser_new_type_id, cp_parser_type_id): Add is_template_arg argument in calls to groktypename. * cp-tree.h: Adjust prototype. * error.c (dump_type_prefix, dump_type_suffix): Fix plain FUNCTION_TYPE printing. PR libstdc++/39310 * include/tr1_impl/type_traits (is_function): Add partial specializations with function cv-quals. (__is_function_helper): Remove. (is_member_pointer): Don't define in terms of is_member_*_pointer. Added: branches/gcc-4_4-branch/gcc/testsuite/g++.dg/other/typedef2.C - copied unchanged from r145367, trunk/gcc/testsuite/g++.dg/other/typedef2.C branches/gcc-4_4-branch/gcc/testsuite/g++.dg/template/typedef17.C - copied unchanged from r145367, trunk/gcc/testsuite/g++.dg/template/typedef17.C Modified: branches/gcc-4_4-branch/gcc/cp/ChangeLog branches/gcc-4_4-branch/gcc/cp/cp-tree.h branches/gcc-4_4-branch/gcc/cp/decl.c branches/gcc-4_4-branch/gcc/cp/decl.h branches/gcc-4_4-branch/gcc/cp/error.c branches/gcc-4_4-branch/gcc/cp/parser.c branches/gcc-4_4-branch/gcc/cp/tree.c branches/gcc-4_4-branch/gcc/cp/typeck.c branches/gcc-4_4-branch/gcc/testsuite/ChangeLog branches/gcc-4_4-branch/gcc/testsuite/g++.dg/template/qualttp20.C branches/gcc-4_4-branch/libstdc++-v3/ChangeLog branches/gcc-4_4-branch/libstdc++-v3/include/tr1_impl/type_traits Fixed for 4.4.0 too. Thanks Jason. |
In the test file libstdc++-v3/testsuite/tr1/4_metaprogramming/is_member_function_pointer/value.cc, the test VERIFY( (test_category<is_member_function_pointer, int (ClassType::*) (int) const>(true)) ); should not PASS IMO. It passes today because of a bug in gcc. More on this in some comments to come below. Why shouldn't it PASS ? Consider: struct remove_const<T> {}; struct remove_const<T const> { typedef T type; }; The is_member_function_pointer template in the value.cc is written based on the assumption that the T in the template parameter of struct remove_const<T const> { typedef T type; }; Should deduce to int (A::*) (void), when we try to instantiate remove_const<int (A::*) (void) const>; Hence, the current implementation of is_member_function_pointer assumes that struct remove_const<T const> { typedef T type; }; should be intantiated. Actually T const is not compatible with int (A::*) (void) vonst; So it's the template struct remove_const<T> {}; that should be instantiated. Not its specialization. So the test VERIFY( (test_category<is_member_function_pointer, int (ClassType::*) (int) const>(true)) ); should not PASS. I will paste in the comments a patch to apply to GCC so that it doesn't compile that test.