https://godbolt.org/z/reG8qE ==== void bar(auto) requires undeclared_identifier; ==== GCC accepts this code.
*** Bug 114946 has been marked as a duplicate of this bug. ***
From PR114946: (In reply to Nathaniel Shead from comment #0) > The following sample compiles fine with 'g++ -std=c++20 -pedantic-errors': > > template <typename T> > requires xxxx > struct S {}; > > template <typename T> > requires xxxx > void foo() {} > > Note that 'xxxx' has not been declared or defined. Both MSVC and Clang > complain about the undeclared identifier. GCC does error if we attempt to > instantiate either of these specialisations, but they always (silently) lose > to a better match: > > template <typename T> struct S {}; > template <typename T> requires xxxx struct S<T> {}; > > template <typename T> void foo() {} > template <typename T> requires xxxx void foo() {} > > int main() { > S<int> x; > foo<int>(); > }
*** Bug 115429 has been marked as a duplicate of this bug. ***
The master branch has been updated by Patrick Palka <ppalka@gcc.gnu.org>: https://gcc.gnu.org/g:d387ecb2b2f44f33fd6a7c5ec7eadaf6dd70efc9 commit r15-1294-gd387ecb2b2f44f33fd6a7c5ec7eadaf6dd70efc9 Author: Patrick Palka <ppalka@redhat.com> Date: Thu Jun 13 10:16:10 2024 -0400 c++: undeclared identifier in requires-clause [PR99678] Since the terms of a requires-clause are grammatically primary-expressions and not e.g. postfix-expressions, it seems we need to explicitly handle and diagnose the case where a term parses to a bare unresolved identifier, like cp_parser_postfix_expression does, since cp_parser_primary_expression leaves that up to its callers. Otherwise we incorrectly accept the first three requires-clauses below. Note that the only occurrences of primary-expression in the grammar are postfix-expression and constraint-logical-and-expression, so it's not too surprising that we need this special handling here. PR c++/99678 gcc/cp/ChangeLog: * parser.cc (cp_parser_constraint_primary_expression): Diagnose a bare unresolved unqualified-id. gcc/testsuite/ChangeLog: * g++.dg/cpp2a/concepts-requires38.C: New test. Reviewed-by: Jason Merrill <jason@redhat.com>
The releases/gcc-14 branch has been updated by Patrick Palka <ppalka@gcc.gnu.org>: https://gcc.gnu.org/g:20cda2e85c307096a3856f7f27215b8a28982fb6 commit r14-10320-g20cda2e85c307096a3856f7f27215b8a28982fb6 Author: Patrick Palka <ppalka@redhat.com> Date: Thu Jun 13 10:16:10 2024 -0400 c++: undeclared identifier in requires-clause [PR99678] Since the terms of a requires-clause are grammatically primary-expressions and not e.g. postfix-expressions, it seems we need to explicitly handle and diagnose the case where a term parses to a bare unresolved identifier, like cp_parser_postfix_expression does, since cp_parser_primary_expression leaves that up to its callers. Otherwise we incorrectly accept the first three requires-clauses below. Note that the only occurrences of primary-expression in the grammar are postfix-expression and constraint-logical-and-expression, so it's not too surprising that we need this special handling here. PR c++/99678 gcc/cp/ChangeLog: * parser.cc (cp_parser_constraint_primary_expression): Diagnose a bare unresolved unqualified-id. gcc/testsuite/ChangeLog: * g++.dg/cpp2a/concepts-requires38.C: New test. Reviewed-by: Jason Merrill <jason@redhat.com> (cherry picked from commit d387ecb2b2f44f33fd6a7c5ec7eadaf6dd70efc9)
Fixed for GCC 14.2, thanks for the bug report.