diff options
author | Jakub Jelinek <jakub@redhat.com> | 2021-04-16 09:34:26 +0200 |
---|---|---|
committer | Jakub Jelinek <jakub@redhat.com> | 2021-04-16 09:34:26 +0200 |
commit | 784de5292c34e287c848b382b431599b818ea76e (patch) | |
tree | 3dc8b374403f140ce4b8a6155a98876e0d6c7cc2 | |
parent | 20eb7a1891cfd7fa85295a236cebe0322d041edd (diff) |
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 <typename T> 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 <jakub@redhat.com>
PR c++/99850
* parser.c (cp_parser_constraint_requires_parens) <case CPP_DEREF>:
If lambda_p, return pce_ok instead of pce_maybe_postfix.
* g++.dg/cpp23/lambda-specifiers2.C: New test.
-rw-r--r-- | gcc/cp/parser.c | 13 | ||||
-rw-r--r-- | gcc/testsuite/g++.dg/cpp23/lambda-specifiers2.C | 7 |
2 files changed, 20 insertions, 0 deletions
diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c index 940751b5f05..dfc9b8251a7 100644 --- a/gcc/cp/parser.c +++ b/gcc/cp/parser.c @@ -28530,7 +28530,20 @@ cp_parser_constraint_requires_parens (cp_parser *parser, bool lambda_p) case CPP_PLUS_PLUS: case CPP_MINUS_MINUS: case CPP_DOT: + /* Unenclosed postfix operator. */ + return pce_maybe_postfix; + case CPP_DEREF: + /* A primary constraint that precedes the lambda-declarator of a + lambda expression is followed by trailing return type. + + []<typename T> requires C -> void {} + + Don't try to re-parse this as a postfix expression in + C++23 and later. In C++20 ( needs to come in between but we + allow it to be omitted with pedwarn. */ + if (lambda_p) + return pce_ok; /* Unenclosed postfix operator. */ return pce_maybe_postfix; } diff --git a/gcc/testsuite/g++.dg/cpp23/lambda-specifiers2.C b/gcc/testsuite/g++.dg/cpp23/lambda-specifiers2.C new file mode 100644 index 00000000000..0cc69bebc64 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp23/lambda-specifiers2.C @@ -0,0 +1,7 @@ +// PR c++/99850 +// P1102R2 - Down with ()! +// { dg-do compile { target c++23 } } + +auto l = []<auto> requires true -> void {}; +template <typename...> concept C = true; +auto m = []<typename... Ts> requires (C<Ts> && ...) -> void {}; |