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* [Bug c++/109775] New: gcc misidentifies a VLA @ 2023-05-08 16:07 janezz55 at gmail dot com 2023-05-08 16:13 ` [Bug c++/109775] " pinskia at gcc dot gnu.org ` (4 more replies) 0 siblings, 5 replies; 6+ messages in thread From: janezz55 at gmail dot com @ 2023-05-08 16:07 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109775 Bug ID: 109775 Summary: gcc misidentifies a VLA Product: gcc Version: 13.1.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: janezz55 at gmail dot com Target Milestone: --- If I compile the example .cpp file: gcc -std=c++20 -Wextra -Wall -Wpedantic add_sub_tests.cpp -o a gcc produces the warning: ../intt.hpp: In member function 'constexpr auto intt::intt< <template-parameter-1-1>, N, <anonymous> >::naimul(const intt::intt< <template-parameter-1-1>, N, <anonymous> >&) const': ../intt.hpp:675:24: warning: ISO C++ forbids variable length array 'v_' [-Wvla] 675 | D const pp(D(v_[i]) * o.v_[S - i]); | ^~ But no VLA is involved and clang++ 15 manages to avoid this issue. The example file is here: https://github.com/user1095108/intt/blob/master/tests/add_sub_tests.cpp I believe the bug was present in prior versions of gcc as well. ^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug c++/109775] gcc misidentifies a VLA 2023-05-08 16:07 [Bug c++/109775] New: gcc misidentifies a VLA janezz55 at gmail dot com @ 2023-05-08 16:13 ` pinskia at gcc dot gnu.org 2023-05-08 16:17 ` pinskia at gcc dot gnu.org ` (3 subsequent siblings) 4 siblings, 0 replies; 6+ messages in thread From: pinskia at gcc dot gnu.org @ 2023-05-08 16:13 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109775 --- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> --- It has to do with parsing here: GCC starts parsing it as a function declaration and then backs out but had already warned/errored out about the VLA. If you change the code to: D const pp{D(v_[i]) * o.v_[S - i]}; Then there is no ambiguity in parsing this. ^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug c++/109775] gcc misidentifies a VLA 2023-05-08 16:07 [Bug c++/109775] New: gcc misidentifies a VLA janezz55 at gmail dot com 2023-05-08 16:13 ` [Bug c++/109775] " pinskia at gcc dot gnu.org @ 2023-05-08 16:17 ` pinskia at gcc dot gnu.org 2023-05-08 16:46 ` pinskia at gcc dot gnu.org ` (2 subsequent siblings) 4 siblings, 0 replies; 6+ messages in thread From: pinskia at gcc dot gnu.org @ 2023-05-08 16:17 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109775 --- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> --- Created attachment 55022 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=55022&action=edit Non reduced testcase ^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug c++/109775] gcc misidentifies a VLA 2023-05-08 16:07 [Bug c++/109775] New: gcc misidentifies a VLA janezz55 at gmail dot com 2023-05-08 16:13 ` [Bug c++/109775] " pinskia at gcc dot gnu.org 2023-05-08 16:17 ` pinskia at gcc dot gnu.org @ 2023-05-08 16:46 ` pinskia at gcc dot gnu.org 2023-05-08 16:48 ` pinskia at gcc dot gnu.org 2023-05-08 16:49 ` pinskia at gcc dot gnu.org 4 siblings, 0 replies; 6+ messages in thread From: pinskia at gcc dot gnu.org @ 2023-05-08 16:46 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109775 Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Last reconfirmed| |2023-05-08 Status|UNCONFIRMED |NEW Ever confirmed|0 |1 --- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> --- Reduced testcase: ``` template <typename T> constexpr void naimul(const T v_[2]) { int i = 1; T pp(T(v_[i])+0); } ``` ^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug c++/109775] gcc misidentifies a VLA 2023-05-08 16:07 [Bug c++/109775] New: gcc misidentifies a VLA janezz55 at gmail dot com ` (2 preceding siblings ...) 2023-05-08 16:46 ` pinskia at gcc dot gnu.org @ 2023-05-08 16:48 ` pinskia at gcc dot gnu.org 2023-05-08 16:49 ` pinskia at gcc dot gnu.org 4 siblings, 0 replies; 6+ messages in thread From: pinskia at gcc dot gnu.org @ 2023-05-08 16:48 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109775 --- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> --- Here is another related testcase: ``` typedef int T; void naimul(const T v_[2]) { int i = 0; T pp(T(v_[0])+0); } ``` We get an -pedantic-error dealing with 0 sized array: <source>: In function 'void naimul(const T*)': <source>:5:13: error: ISO C++ forbids zero-size array 'v_' [-Wpedantic] 5 | T pp(T(v_[0])+0); | ^ ^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug c++/109775] gcc misidentifies a VLA 2023-05-08 16:07 [Bug c++/109775] New: gcc misidentifies a VLA janezz55 at gmail dot com ` (3 preceding siblings ...) 2023-05-08 16:48 ` pinskia at gcc dot gnu.org @ 2023-05-08 16:49 ` pinskia at gcc dot gnu.org 4 siblings, 0 replies; 6+ messages in thread From: pinskia at gcc dot gnu.org @ 2023-05-08 16:49 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109775 Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Depends on| |61259 --- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> --- (In reply to Andrew Pinski from comment #4) > Here is another related testcase: > ``` > typedef int T; > void naimul(const T v_[2]) > { > int i = 0; > T pp(T(v_[0])+0); > } > ``` > We get an -pedantic-error dealing with 0 sized array: > <source>: In function 'void naimul(const T*)': > <source>:5:13: error: ISO C++ forbids zero-size array 'v_' [-Wpedantic] > 5 | T pp(T(v_[0])+0); > | ^ That is recorded as PR 61259 . Referenced Bugs: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61259 [Bug 61259] [10/11/12/13/14 Regression] Spurious "ISO C++ forbids zero-size array" warning with -pedantic ^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2023-05-08 16:49 UTC | newest] Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2023-05-08 16:07 [Bug c++/109775] New: gcc misidentifies a VLA janezz55 at gmail dot com 2023-05-08 16:13 ` [Bug c++/109775] " pinskia at gcc dot gnu.org 2023-05-08 16:17 ` pinskia at gcc dot gnu.org 2023-05-08 16:46 ` pinskia at gcc dot gnu.org 2023-05-08 16:48 ` pinskia at gcc dot gnu.org 2023-05-08 16:49 ` pinskia at gcc dot gnu.org
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