https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102293
--- Comment #1 from andysem at mail dot ru --- I forgot to mention that the same code compiles successfully with gcc 9.4.0. And here is the output from gcc 11.1.0: In file included from ./boost/assert.hpp:58, from ./boost/xpressive/detail/core/matcher/simple_repeat_matcher.hpp:16, from ./boost/xpressive/detail/core/matchers.hpp:46, from ./boost/xpressive/detail/core/linker.hpp:35, from ./boost/xpressive/detail/static/static.hpp:19, from ./boost/xpressive/detail/static/transforms/as_matcher.hpp:18, from ./boost/xpressive/detail/static/grammar.hpp:21, from ./boost/xpressive/basic_regex.hpp:28, from ./boost/xpressive/regex_compiler.hpp:30, from ./boost/xpressive/xpressive_dynamic.hpp:17, from libs/log/test/run/filt_matches_xpressive.cpp:18: ./boost/xpressive/detail/core/matcher/simple_repeat_matcher.hpp: In instantiation of ‘boost::xpressive::detail::simple_repeat_matcher<Xpr, Greedy>::simple_repeat_matcher(const Xpr&, unsigned int, unsigned int, std::size_t) [with Xpr = boost::xpressive::detail::matcher_wrapper<boost::xpressive::detail::charset_matcher<boost::xpressive::regex_traits<char, boost::xpressive::cpp_regex_traits<char> >, mpl_::bool_<false>, boost::xpressive::detail::compound_charset<boost::xpressive::regex_traits<char, boost::xpressive::cpp_regex_traits<char> > > > >; Greedy = mpl_::bool_<true>; std::size_t = long unsigned int]’: ./boost/xpressive/detail/dynamic/dynamic.hpp:216:48: required from ‘void boost::xpressive::detail::make_simple_repeat(const boost::xpressive::detail::quant_spec&, boost::xpressive::detail::sequence<BidiIter>&, const Xpr&) [with BidiIter = const char*; Xpr = boost::xpressive::detail::matcher_wrapper<boost::xpressive::detail::charset_matcher<boost::xpressive::regex_traits<char, boost::xpressive::cpp_regex_traits<char> >, mpl_::bool_<false>, boost::xpressive::detail::compound_charset<boost::xpressive::regex_traits<char, boost::xpressive::cpp_regex_traits<char> > > > >]’ ./boost/xpressive/detail/dynamic/dynamic.hpp:130:31: required from ‘void boost::xpressive::detail::dynamic_xpression<Matcher, BidiIter>::repeat_(const boost::xpressive::detail::quant_spec&, boost::xpressive::detail::sequence<BidiIter>&, mpl_::int_<1>, mpl_::false_) const [with Matcher = boost::xpressive::detail::charset_matcher<boost::xpressive::regex_traits<char, boost::xpressive::cpp_regex_traits<char> >, mpl_::bool_<false>, boost::xpressive::detail::compound_charset<boost::xpressive::regex_traits<char, boost::xpressive::cpp_regex_traits<char> > > >; BidiIter = const char*; mpl_::false_ = mpl_::bool_<false>]’ ./boost/xpressive/detail/dynamic/dynamic.hpp:96:22: required from ‘void boost::xpressive::detail::dynamic_xpression<Matcher, BidiIter>::repeat(const boost::xpressive::detail::quant_spec&, boost::xpressive::detail::sequence<BidiIter>&) const [with Matcher = boost::xpressive::detail::charset_matcher<boost::xpressive::regex_traits<char, boost::xpressive::cpp_regex_traits<char> >, mpl_::bool_<false>, boost::xpressive::detail::compound_charset<boost::xpressive::regex_traits<char, boost::xpressive::cpp_regex_traits<char> > > >; BidiIter = const char*]’ ./boost/xpressive/detail/dynamic/dynamic.hpp:94:18: required from here ./boost/xpressive/detail/core/matcher/simple_repeat_matcher.hpp:81:37: internal compiler error: in value_dependent_expression_p, at cp/pt.c:26978 81 | BOOST_ASSERT(0 != width && unknown_width() != width); | ~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~ ./boost/xpressive/detail/core/matcher/simple_repeat_matcher.hpp:81:13: note: in expansion of macro ‘BOOST_ASSERT’ 81 | BOOST_ASSERT(0 != width && unknown_width() != width); | ^~~~~~~~~~~~ 0xe306b3 internal_error(char const*, ...) ???:0 0xe27039 fancy_abort(char const*, int, char const*) ???:0 0xf5208e value_dependent_expression_p(tree_node*) ???:0 0xf520a9 value_dependent_expression_p(tree_node*) ???:0 0x10ed97e tsubst_copy_and_build(tree_node*, tree_node*, int, tree_node*, bool, bool) ???:0 0x10eddd9 tsubst_copy_and_build(tree_node*, tree_node*, int, tree_node*, bool, bool) ???:0 0x10ee17a tsubst_copy_and_build(tree_node*, tree_node*, int, tree_node*, bool, bool) ???:0 0x1178f37 tsubst_expr(tree_node*, tree_node*, int, tree_node*, bool) ???:0 0x117910c tsubst_expr(tree_node*, tree_node*, int, tree_node*, bool) ???:0 0x1179047 tsubst_expr(tree_node*, tree_node*, int, tree_node*, bool) ???:0 0x1178f95 tsubst_expr(tree_node*, tree_node*, int, tree_node*, bool) ???:0 0x1179047 tsubst_expr(tree_node*, tree_node*, int, tree_node*, bool) ???:0 0x1178f95 tsubst_expr(tree_node*, tree_node*, int, tree_node*, bool) ???:0 0x122150a instantiate_decl(tree_node*, bool, bool) ???:0 0xfa3850 instantiate_pending_templates(int) ???:0 0xf9f8f3 c_parse_final_cleanups() ???:0 Please submit a full bug report, with preprocessed source if appropriate. Please include the complete backtrace with any bug report. See <file:///usr/share/doc/gcc-11/README.Bugs> for instructions. "g++-11" -ftemplate-depth-1024 -std=c++03 -fPIC -m64 -pthread -O0 -fno-inline -Wall -g -fno-strict-aliasing -DBOOST_ALL_NO_LIB=1 -DBOOST_ATOMIC_DYN_LINK=1 -DBOOST_CHRONO_DYN_LINK=1 -DBOOST_FILESYSTEM_DYN_LINK=1 -DBOOST_LOG_DYN_LINK=1 -DBOOST_LOG_SETUP_DYN_LINK=1 -DBOOST_LOG_USE_AVX2 -DBOOST_LOG_USE_SSSE3 -DBOOST_TEST_DYN_LINK=1 -DBOOST_TEST_NO_AUTO_LINK=1 -DBOOST_THREAD_BUILD_DLL=1 -DBOOST_THREAD_POSIX -DBOOST_THREAD_USE_DLL=1 -D_XOPEN_SOURCE=600 -I"." -I"libs/log/test/common" -c -o "bin.v2/libs/log/test/filt_matches_xpressive.test/gcc-11/debug/cxxstd-03-iso/threadapi-pthread/threading-multi/run/filt_matches_xpressive.o" "libs/log/test/run/filt_matches_xpressive.cpp"