https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69794
Bug ID: 69794 Summary: [5 Regression] std::regex_search match failure with regex object with flags grep|icase Product: gcc Version: 5.3.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: libstdc++ Assignee: unassigned at gcc dot gnu.org Reporter: andrey.vul at gmail dot com Target Milestone: --- I have observed a regression in std::regex_search when the regex object has flags grep | icase and is multi-line for grep semantics. The following testcase works as expected in GCC 4.9.3 and clang 3.7 with libc++. The failing behavior is observed in gcc 5.3.0 and is reproducible when gcc 5.3 stdlib is used with clang 3.7. Gcc 5.1 and 5.2 were not tested. TC: // begin re.cc #include <regex> #include <string> int main() { std::string re_str { "/abcd" "\n" "/aecf" "\n" "/ghci" }; auto rx = std::regex(re_str, std::regex_constants::grep | std::regex_constants::icase); std::cmatch result; return !std::regex_search("/abcd", result, rx); } // end re.cc INVOCATION: gcc -std=c++11 re.cc && ./a.out; echo $? OUTPUT: EXPECTED: 0 ACTUAL: 1 GCC VERSION: gcc -v: Using built-in specs. COLLECT_GCC=/usr/x86_64-pc-linux-gnu/gcc-bin/5.3.0/gcc COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-pc-linux-gnu/5.3.0/lto-wrapper Target: x86_64-pc-linux-gnu Configured with: /var/tmp/portage/sys-devel/gcc-5.3.0/work/gcc-5.3.0/configure --host=x86_64-pc-linux-gnu --build=x86_64-pc-linux-gnu --prefix=/usr --bindir=/usr/x86_64-pc-linux-gnu/gcc-bin/5.3.0 --includedir=/usr/lib/gcc/x86_64-pc-linux-gnu/5.3.0/include --datadir=/usr/share/gcc-data/x86_64-pc-linux-gnu/5.3.0 --mandir=/usr/share/gcc-data/x86_64-pc-linux-gnu/5.3.0/man --infodir=/usr/share/gcc-data/x86_64-pc-linux-gnu/5.3.0/info --with-gxx-include-dir=/usr/lib/gcc/x86_64-pc-linux-gnu/5.3.0/include/g++-v5 --with-python-dir=/share/gcc-data/x86_64-pc-linux-gnu/5.3.0/python --enable-languages=c,c++,fortran --enable-obsolete --enable-secureplt --disable-werror --with-system-zlib --enable-nls --without-included-gettext --enable-checking=release --with-bugurl=https://bugs.gentoo.org/ --with-pkgversion='Gentoo 5.3.0 p1.0, pie-0.6.5' --enable-libstdcxx-time --enable-shared --enable-threads=posix --enable-__cxa_atexit --enable-clocale=gnu --enable-multilib --with-multilib-list=m32,m64 --disable-altivec --disable-fixed-point --enable-targets=all --disable-libgcj --enable-libgomp --disable-libmudflap --disable-libssp --enable-libcilkrts --enable-lto --with-isl --disable-isl-version-check --enable-libsanitizer Thread model: posix gcc version 5.3.0 (Gentoo 5.3.0 p1.0, pie-0.6.5)