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* [Bug c++/98824] New: [C++-20] function template non-type-class-arg deduction fails with a reason that looks bogus @ 2021-01-25 16:18 dimitri.gorokhovik at free dot fr 2021-01-27 15:33 ` [Bug c++/98824] " dimitri.gorokhovik at free dot fr ` (3 more replies) 0 siblings, 4 replies; 5+ messages in thread From: dimitri.gorokhovik at free dot fr @ 2021-01-25 16:18 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98824 Bug ID: 98824 Summary: [C++-20] function template non-type-class-arg deduction fails with a reason that looks bogus Product: gcc Version: 11.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: dimitri.gorokhovik at free dot fr Target Milestone: --- The code: template <auto> struct a {}; template <int i, a <i> v> constexpr auto f (a <v>) { return true; }; constexpr a <1> b; auto const p = f (a <b> {}); when compiled with 'g++ -std=c++20 -c bug-14.cpp' (g++ (GCC) 11.0.0 20210123 (experimental)), produces: bug-14.cpp:5:27: error: no matching function for call to ‘f(a<a<1>()>)’ 5 | auto const p = f (a <b> {}); | ^ bug-14.cpp:2:42: note: candidate: ‘template<int i, a<i> v> constexpr auto f(a<((const a<i>)v)>)’ 2 | template <int i, a <i> v> constexpr auto f (a <v>) { return true; }; | ^ bug-14.cpp:2:42: note: template argument deduction/substitution failed: bug-14.cpp:5:27: note: types ‘a<i>’ and ‘const a<1>’ have incompatible cv-qualifiers 5 | auto const p = f (a <b> {}); clang-12 seems to accept it (hits a non-implemented feature in a subsequent pass). The diagnostics looks confusing/misleading: -- compiler is aware of the constness of 'a <i>' -- see the signature of f() in the note for line 2. And then it seemingly removes 'const' from 'const a <i>', maybe expecting a certain strictness level in 'unify()'. However, unify() is called with strict=UNIFY_ALLOW_NONE. ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/98824] [C++-20] function template non-type-class-arg deduction fails with a reason that looks bogus 2021-01-25 16:18 [Bug c++/98824] New: [C++-20] function template non-type-class-arg deduction fails with a reason that looks bogus dimitri.gorokhovik at free dot fr @ 2021-01-27 15:33 ` dimitri.gorokhovik at free dot fr 2021-08-17 9:24 ` pinskia at gcc dot gnu.org ` (2 subsequent siblings) 3 siblings, 0 replies; 5+ messages in thread From: dimitri.gorokhovik at free dot fr @ 2021-01-27 15:33 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98824 --- Comment #1 from Dimitri Gorokhovik <dimitri.gorokhovik at free dot fr> --- It doesn't seem to contradict N4868 :-( Modifying the code slightly (adding refs, splitting deduction across two fn templates) didn't show any other differences from clang: all other modification either both pass or both fail with the equivalent messages ("'i' cannot be deduced"). This is the only one. clang version: Ubuntu clang version 12.0.0-++20201102052620+327bf5c2d91-1~exp1~20201102163303.210 Target: x86_64-pc-linux-gnu ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/98824] [C++-20] function template non-type-class-arg deduction fails with a reason that looks bogus 2021-01-25 16:18 [Bug c++/98824] New: [C++-20] function template non-type-class-arg deduction fails with a reason that looks bogus dimitri.gorokhovik at free dot fr 2021-01-27 15:33 ` [Bug c++/98824] " dimitri.gorokhovik at free dot fr @ 2021-08-17 9:24 ` pinskia at gcc dot gnu.org 2022-01-18 5:50 ` bernie at codewiz dot org 2022-01-18 5:51 ` bernie at codewiz dot org 3 siblings, 0 replies; 5+ messages in thread From: pinskia at gcc dot gnu.org @ 2021-08-17 9:24 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98824 Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Ever confirmed|0 |1 Status|UNCONFIRMED |NEW Keywords| |rejects-valid Last reconfirmed| |2021-08-17 --- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> --- Confirmed. ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/98824] [C++-20] function template non-type-class-arg deduction fails with a reason that looks bogus 2021-01-25 16:18 [Bug c++/98824] New: [C++-20] function template non-type-class-arg deduction fails with a reason that looks bogus dimitri.gorokhovik at free dot fr 2021-01-27 15:33 ` [Bug c++/98824] " dimitri.gorokhovik at free dot fr 2021-08-17 9:24 ` pinskia at gcc dot gnu.org @ 2022-01-18 5:50 ` bernie at codewiz dot org 2022-01-18 5:51 ` bernie at codewiz dot org 3 siblings, 0 replies; 5+ messages in thread From: bernie at codewiz dot org @ 2022-01-18 5:50 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98824 Bernie Innocenti <bernie at codewiz dot org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |bernie at codewiz dot org --- Comment #3 from Bernie Innocenti <bernie at codewiz dot org> --- Assuming this is the same bug, it's still present in g++ 12 as well as trunk: https://godbolt.org/z/6r3bc3j15 ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/98824] [C++-20] function template non-type-class-arg deduction fails with a reason that looks bogus 2021-01-25 16:18 [Bug c++/98824] New: [C++-20] function template non-type-class-arg deduction fails with a reason that looks bogus dimitri.gorokhovik at free dot fr ` (2 preceding siblings ...) 2022-01-18 5:50 ` bernie at codewiz dot org @ 2022-01-18 5:51 ` bernie at codewiz dot org 3 siblings, 0 replies; 5+ messages in thread From: bernie at codewiz dot org @ 2022-01-18 5:51 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98824 --- Comment #4 from Bernie Innocenti <bernie at codewiz dot org> --- Are there any known workarounds? ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2022-01-18 5:51 UTC | newest] Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2021-01-25 16:18 [Bug c++/98824] New: [C++-20] function template non-type-class-arg deduction fails with a reason that looks bogus dimitri.gorokhovik at free dot fr 2021-01-27 15:33 ` [Bug c++/98824] " dimitri.gorokhovik at free dot fr 2021-08-17 9:24 ` pinskia at gcc dot gnu.org 2022-01-18 5:50 ` bernie at codewiz dot org 2022-01-18 5:51 ` bernie at codewiz dot org
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