[Bug c++/99850] [P1102R2] reject valid lambda syntax in C++23
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99850 Jakub Jelinek changed: What|Removed |Added Resolution|--- |FIXED Assignee|mpolacek at gcc dot gnu.org|jakub at gcc dot gnu.org Status|ASSIGNED|RESOLVED --- Comment #7 from Jakub Jelinek --- Fixed.
[Bug c++/99850] [P1102R2] reject valid lambda syntax in C++23
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99850
--- Comment #6 from CVS Commits ---
The master branch has been updated by Jakub Jelinek :
https://gcc.gnu.org/g:784de5292c34e287c848b382b431599b818ea76e
commit r11-8210-g784de5292c34e287c848b382b431599b818ea76e
Author: Jakub Jelinek
Date: Fri Apr 16 09:34:26 2021 +0200
c++: Fix up C++23 [] <...> requires primary -> type {} parsing [PR99850]
The requires clause parsing has code to suggest users wrapping
non-primary expressions in (), so if it e.g. parses a primary expression
and sees it is followed by ++, --, ., ( or -> among other things it
will try to reparse it as assignment expression or what and if that works
suggests wrapping it inside of parens.
When it is requires-clause that is after etc. it already
has an exception from that as ( can occur in valid C++20 expression there
- starting the parameters of the lambda.
In C++23 another case can occur, as the parameters with the ()s can be
omitted, requires C can be followed immediately by -> which starts a
trailing return type. Even in that case, we don't want to parse that
as C->...
2021-04-16 Jakub Jelinek
PR c++/99850
* parser.c (cp_parser_constraint_requires_parens) :
If lambda_p, return pce_ok instead of pce_maybe_postfix.
* g++.dg/cpp23/lambda-specifiers2.C: New test.
[Bug c++/99850] [P1102R2] reject valid lambda syntax in C++23
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99850 --- Comment #5 from Jakub Jelinek --- Created attachment 50592 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=50592&action=edit gcc11-pr99850.patch Untested fix.
[Bug c++/99850] [P1102R2] reject valid lambda syntax in C++23
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99850
--- Comment #4 from 康桓瑋 ---
This ICE may be caused by not handle this form.
template concept C = true;
auto l = [] requires (C && ...) -> void {};
https://godbolt.org/z/vo8xPd4hY
:3:48: internal compiler error: Segmentation fault
3 | auto l = [] requires (C && ...) -> void {};
|^~~
0x1cfca39 internal_error(char const*, ...)
???:0
0x940286 convert_generic_types_to_packs(tree_node*, int, int)
???:0
0x8e126d c_parse_file()
???:0
0xa60292 c_common_parse_file()
???:0
Please submit a full bug report,
with preprocessed source if appropriate.
[Bug c++/99850] [P1102R2] reject valid lambda syntax in C++23
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99850
Jakub Jelinek changed:
What|Removed |Added
CC||jakub at gcc dot gnu.org
--- Comment #3 from Jakub Jelinek ---
Ah, but in lambda-expression: non-terminal there is another
requires-clause[opt] after the < template-parameter-list >.
So we need to handle
auto l = [] requires true (T t, int n) { };
But during parsing we have parsing of requires clause at that spot after >,
and when ()s are omitted, there is code to handle -> at that spot.
[Bug c++/99850] [P1102R2] reject valid lambda syntax in C++23
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99850 --- Comment #2 from Jakub Jelinek --- Are you sure it is incorrectly rejected? http://eel.is/c++draft/expr.prim.lambda.general says: lambda-declarator: lambda-specifiers ( parameter-declaration-clause ) lambda-specifiers requires-clause[opt] So in my reading, if requires-clause is present, the ()s are not optional. Otherwise requires-clause[opt] would need to be in the lambda-specifiers non-terminal or present also after the first lambda-specifiers.
[Bug c++/99850] [P1102R2] reject valid lambda syntax in C++23
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99850 Marek Polacek changed: What|Removed |Added Status|NEW |ASSIGNED Assignee|unassigned at gcc dot gnu.org |mpolacek at gcc dot gnu.org
[Bug c++/99850] [P1102R2] reject valid lambda syntax in C++23
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99850 Marek Polacek changed: What|Removed |Added CC||mpolacek at gcc dot gnu.org Last reconfirmed||2021-03-31 Status|UNCONFIRMED |NEW Ever confirmed|0 |1 Keywords||rejects-valid --- Comment #1 from Marek Polacek --- Confirmed. I could take a look, unless Jakub wants it.
