https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102447
--- Comment #13 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The releases/gcc-10 branch has been updated by Jonathan Wakely <r...@gcc.gnu.org>: https://gcc.gnu.org/g:4c347b8d59958d5aa76c5fdcecd72478e08c5aa3 commit r10-11465-g4c347b8d59958d5aa76c5fdcecd72478e08c5aa3 Author: Jonathan Wakely <jwak...@redhat.com> Date: Tue Dec 14 14:32:35 2021 +0000 libstdc++: Fix handling of invalid ranges in std::regex [PR102447] std::regex currently allows invalid bracket ranges such as [\w-a] which are only allowed by ECMAScript when in web browser compatibility mode. It should be an error, because the start of the range is a character class, not a single character. The current implementation of _Compiler::_M_expression_term does not provide a way to reject this, because we only remember a previous character, not whether we just processed a character class (or collating symbol etc.) This patch replaces the pair<bool, CharT> used to emulate optional<CharT> with a custom class closer to pair<tribool,CharT>. That allows us to track three states, so that we can tell when we've just seen a character class. With this additional state the code in _M_expression_term for processing the _S_token_bracket_dash can be improved to correctly reject the [\w-a] case, without regressing for valid cases such as [\w-] and [----]. libstdc++-v3/ChangeLog: PR libstdc++/102447 * include/bits/regex_compiler.h (_Compiler::_BracketState): New class. (_Compiler::_BrackeyMatcher): New alias template. (_Compiler::_M_expression_term): Change pair<bool, CharT> parameter to _BracketState. Process first character for ECMAScript syntax as well as POSIX. * include/bits/regex_compiler.tcc (_Compiler::_M_insert_bracket_matcher): Pass _BracketState. (_Compiler::_M_expression_term): Use _BracketState to store state between calls. Improve handling of dashes in ranges. * testsuite/28_regex/algorithms/regex_match/cstring_bracket_01.cc: Add more tests for ranges containing dashes. Check invalid ranges with character class at the beginning. (cherry picked from commit 7ce3c230edf6e498e125c805a6dd313bf87dc439)
