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* [Bug c++/102184] New: Explicit template instantiation is wrongly considered as specialization @ 2021-09-03 6:52 fchelnokov at gmail dot com 2021-09-03 7:03 ` [Bug c++/102184] " pinskia at gcc dot gnu.org 2021-09-03 7:07 ` [Bug c++/102184] Explicit template instantiation thinks there is an ambiguous template specialization when there is none for concepts pinskia at gcc dot gnu.org 0 siblings, 2 replies; 3+ messages in thread From: fchelnokov at gmail dot com @ 2021-09-03 6:52 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102184 Bug ID: 102184 Summary: Explicit template instantiation is wrongly considered as specialization Product: gcc Version: 12.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: fchelnokov at gmail dot com Target Milestone: --- In this code: ``` template<int N> requires(N==1) int fib() { return 1; } template<int N> requires(N==2) int fib() { return 1; } template<int N> int fib() { return fib<N-1>() + fib<N-2>(); } template int fib<1>(); ``` the last line with function explicit instantiation produces GCC error: ambiguous template specialization 'fib<1>' for 'int fib()' The other compilers are fine with the code: https://gcc.godbolt.org/z/fbMGs3hqY ^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug c++/102184] Explicit template instantiation is wrongly considered as specialization 2021-09-03 6:52 [Bug c++/102184] New: Explicit template instantiation is wrongly considered as specialization fchelnokov at gmail dot com @ 2021-09-03 7:03 ` pinskia at gcc dot gnu.org 2021-09-03 7:07 ` [Bug c++/102184] Explicit template instantiation thinks there is an ambiguous template specialization when there is none for concepts pinskia at gcc dot gnu.org 1 sibling, 0 replies; 3+ messages in thread From: pinskia at gcc dot gnu.org @ 2021-09-03 7:03 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102184 Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Keywords| |diagnostic --- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> --- GCC is saying there is an ambigous specialization. If I do this, GCC accepts the code: template<int N> requires(N==1) int fib() { return 1; } template<int N> requires(N==2) int fib() { return 1; } template<int N> int fib() requires(N!=1 && N!=2) { return fib<N-1>() + fib<N-2>(); } template int fib<1>(); ^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug c++/102184] Explicit template instantiation thinks there is an ambiguous template specialization when there is none for concepts 2021-09-03 6:52 [Bug c++/102184] New: Explicit template instantiation is wrongly considered as specialization fchelnokov at gmail dot com 2021-09-03 7:03 ` [Bug c++/102184] " pinskia at gcc dot gnu.org @ 2021-09-03 7:07 ` pinskia at gcc dot gnu.org 1 sibling, 0 replies; 3+ messages in thread From: pinskia at gcc dot gnu.org @ 2021-09-03 7:07 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102184 Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Ever confirmed|0 |1 Status|UNCONFIRMED |NEW Last reconfirmed| |2021-09-03 Keywords| |rejects-valid Summary|Explicit template |Explicit template |instantiation is wrongly |instantiation thinks there |considered as |is an ambiguous template |specialization |specialization when there | |is none for concepts --- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> --- (In reply to Andrew Pinski from comment #1) > GCC is saying there is an ambigous specialization. > > If I do this, GCC accepts the code: > template<int N> requires(N==1) int fib() { return 1; } > template<int N> requires(N==2) int fib() { return 1; } > template<int N> int fib() requires(N!=1 && N!=2) { return fib<N-1>() + > fib<N-2>(); } > template int fib<1>(); But I think GCC does not know which specialization to instantiate here. Because the following works just fine: int t = fib<1>(); ^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2021-09-03 7:07 UTC | newest] Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2021-09-03 6:52 [Bug c++/102184] New: Explicit template instantiation is wrongly considered as specialization fchelnokov at gmail dot com 2021-09-03 7:03 ` [Bug c++/102184] " pinskia at gcc dot gnu.org 2021-09-03 7:07 ` [Bug c++/102184] Explicit template instantiation thinks there is an ambiguous template specialization when there is none for concepts pinskia at gcc dot gnu.org
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