[Bug c++/101783] unnecessary error when top level cv qualifier is dropped
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101783 Patrick Palka changed: What|Removed |Added CC||rs2740 at gmail dot com --- Comment #12 from Patrick Palka --- *** Bug 69778 has been marked as a duplicate of this bug. ***
[Bug c++/101783] unnecessary error when top level cv qualifier is dropped
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101783 Patrick Palka changed: What|Removed |Added Target Milestone|--- |12.0 Resolution|--- |FIXED CC||ppalka at gcc dot gnu.org Status|NEW |RESOLVED Assignee|unassigned at gcc dot gnu.org |nickhuang99 at hotmail dot com --- Comment #11 from Patrick Palka --- Marking as fixed for GCC 12, thanks for working on this!
[Bug c++/101783] unnecessary error when top level cv qualifier is dropped
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101783 --- Comment #10 from CVS Commits --- The master branch has been updated by Jason Merrill : https://gcc.gnu.org/g:7c99923f8c544ec07109e8333acb2c2388c38a1b commit r12-4051-g7c99923f8c544ec07109e8333acb2c2388c38a1b Author: qingzhe huang Date: Fri Oct 1 10:46:35 2021 -0400 c++: cv-qualified ref introduced by typedef [PR101783] The root cause of this bug is that it considers reference with cv-qualifiers as an error by generating value for variable "bad_quals". However, this is not correct for case of typedef. Here I quote spec [dcl.ref]/1 : "Cv-qualified references are ill-formed except when the cv-qualifiers are introduced through the use of a typedef-name ([dcl.typedef], [temp.param]) or decltype-specifier ([dcl.type.decltype]), in which case the cv-qualifiers are ignored." 2021-09-30 qingzhe huang gcc/cp/ChangeLog: PR c++/101783 * tree.c (cp_build_qualified_type_real): Exclude typedef from error. gcc/testsuite/ChangeLog: PR c++/101783 * g++.dg/parse/pr101783.C: New test.
[Bug c++/101783] unnecessary error when top level cv qualifier is dropped
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101783 --- Comment #9 from qingzhe huang --- OK, Thank you very much! From: redi at gcc dot gnu.org Sent: August 23, 2021 9:37 AM To: nickhuan...@hotmail.com Subject: [Bug c++/101783] unnecessary error when top level cv qualifier is dropped https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101783 --- Comment #8 from Jonathan Wakely --- No, I cannot approve compiler patches. -- You are receiving this mail because: You reported the bug. You are on the CC list for the bug.
[Bug c++/101783] unnecessary error when top level cv qualifier is dropped
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101783 --- Comment #8 from Jonathan Wakely --- No, I cannot approve compiler patches.
[Bug c++/101783] unnecessary error when top level cv qualifier is dropped
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101783 --- Comment #7 from qingzhe huang --- Jonathan, Is it possible for you to review and commit my patch? (https://gcc.gnu.org/pipermail/gcc-patches/2021-August/577040.html). Thank you!
[Bug c++/101783] unnecessary error when top level cv qualifier is dropped
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101783 --- Comment #6 from Jonathan Wakely --- Please send patches to the mailing list for review, they are likely to get ignored or forgotten in bugzilla. https://gcc.gnu.org/contribute.html#patches
[Bug c++/101783] unnecessary error when top level cv qualifier is dropped
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101783 nick huang changed: What|Removed |Added CC||nickhuang99 at hotmail dot com --- Comment #5 from nick huang --- Created attachment 51274 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=51274&action=edit suggested fix for PR101783 Here is my suggested fix for this bug. The root cause of this bug is that it considers reference with cv qualifier as an error by generating value for variable "bad_quals". However, this is not correct for case of typedef. Here I quote spec: "Cv-qualified references are ill-formed except when the cv-qualifiers are introduced through the use of a typedef-name ([dcl.typedef], [temp.param]) or decltype-specifier ([dcl.type.decltype]), in which case the cv-qualifiers are ignored."
[Bug c++/101783] unnecessary error when top level cv qualifier is dropped
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101783
--- Comment #4 from Jonathan Wakely ---
(In reply to nick huang from comment #0)
> The signature of *f* would drop unnecessary const anyway as top-level
> cv qualifier according to spec. So, there is no need to generate error.
>
> 2. clang gives a warning but still accept it of which I believe appropriate
> (https://www.godbolt.org/z/9qWrj5asq). MSVC accept without complaining
> (https://www.godbolt.org/z/3coqMnjjq).
EDG warns too:
"101783.C", line 8: warning: type qualifiers are meaningless here
void f(const typename A::Type){}
^
[Bug c++/101783] unnecessary error when top level cv qualifier is dropped
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101783 --- Comment #3 from Jonathan Wakely --- GCC 4.4 and earlier didn't accept it with the typename there: 101783.C:8: error: using 'typename' outside of template 101783.C:8: error: 'const' qualifiers cannot be applied to 'B&' The typename started to be accepted with r0-94634 re PR c++/22154 ([DR 382] qualified names should allow typename keyword in front of it (even in non-templates)) 2009-07-13 Andrew Pinski PR C++/22154 * parser.c (cp_parser_elaborated_type_specifier): Accept typename in front of qualified names. 2009-07-13 Andrew Pinski PR C++/22154 * g++.old-deja/g++.pt/typename10.C: Update for DR 382, typename in front of qualified names are allowed. * g++.dg/parse/crash10.C: Likewise. * g++.dg/parse/error15.C: Likewise. * g++.dg/parse/typename9.C: Likewise. * g++.dg/parse/error8.C: Likewise. From-SVN: r149590
[Bug c++/101783] unnecessary error when top level cv qualifier is dropped
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101783
Jonathan Wakely changed:
What|Removed |Added
Keywords|diagnostic |
Last reconfirmed||2021-08-06
Ever confirmed|0 |1
Status|UNCONFIRMED |NEW
--- Comment #2 from Jonathan Wakely ---
Confirmed, doesn't seem to be a regression.
It compiles if you remove the typename:
template struct A{
typedef T& Type;
};
template
void f(const typename A::Type){}
struct B{};
template <>
void f(const A::Type){}
[Bug c++/101783] unnecessary error when top level cv qualifier is dropped
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101783
--- Comment #1 from nick huang ---
The following snippet of code and error gives more clear the issue.
Considering:
template struct A{
typedef T& Type;
};
template
void f(const typename A::Type){}
struct B{};
template <>
void f(const typename A::Type){}
generates following error:
error: ‘const’ qualifiers cannot be applied to ‘A::Type {aka B&}’
void f(const typename A::Type){}
^~~~
This would obviously confuses users about why *const* cannot be applied. Being
unable to apply the *const* to *B&* SHOULD NOT be an error, instead it is
merely a warning to be issued.
