https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111330
--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> --- So, narrowed it down to Fedora build doing essentially (stripped down from all languages etc.): CC=gcc \ CXX=g++ \ CFLAGS='-O2 -fexceptions -g -grecord-gcc-switches -Wall -Wformat-security -Wp,-D_GLIBCXX_ASSERTIONS -mtune=generic -fasynchronous-unwind-tables -fstack-clash-protection -fcf-protection' \ CXXFLAGS=' -O2 -g -grecord-gcc-switches -Wformat -Wformat-security -Wp,-D_GLIBCXX_ASSERTIONS -mtune=generic -fasynchronous-unwind-tables -fstack-clash-protection -fcf-protection ' \ XCFLAGS='-O2 -fexceptions -g -grecord-gcc-switches -Wall -Wformat-security -Wp,-D_GLIBCXX_ASSERTIONS -mtune=generic -fasynchronous-unwind-tables -fstack-clash-protection -fcf-protection' \ TCFLAGS='-O2 -fexceptions -g -grecord-gcc-switches -Wall -Wformat-security -Wp,-D_GLIBCXX_ASSERTIONS -mtune=generic -fasynchronous-unwind-tables -fstack-clash-protection -fcf-protection' \ ../configure --disable-bootstrap --enable-languages=c,c++,m2,lto --enable-checking=release --enable-multilib --disable-libsanitizer --with-gcc-major-version-only --enable-plugin --enable-gnu-indirect-function --enable-cet --with-tune=generic --with-arch_32=i686 --build=x86_64-redhat-linux make -j32 'BOOT_CFLAGS=-O2 -fexceptions -g -grecord-gcc-switches -Wall -Wformat-security -Wp,-D_GLIBCXX_ASSERTIONS -mtune=generic -fasynchronous-unwind-tables -fstack-clash-protection -fcf-protection' LDFLAGS_FOR_TARGET=-Wl,-z,relro,-z,now And what matters is using -Wall during the build in *FLAGS. /builddir/build/BUILD/gcc-13.2.1-20230728/obj-x86_64-redhat-linux/./gcc/gm2 -B/builddir/build/BUILD/gcc-13.2.1-20230728/obj-x86_64-redhat-linux/./gcc/ -c -O2 -Wall -fm2-pathname=m2iso -I. -Ilibm2iso -I/builddir/build/BUILD/gcc-13.2.1-20230728/gcc/m2/gm2-libs-iso -fm2-pathname=m2pim -I/builddir/build/BUILD/gcc-13.2.1-20230728/gcc/m2/gm2-libs -fiso -fextended-opaque -fm2-g -g -Wreturn-type -fcase -fm2-prefix=m2iso ../../../../libgm2/libm2iso/../../gcc/m2/gm2-libs-iso/SeqFile.mod -fPIC -DPIC -o .libs/SeqFile.o; echo $? ../../gcc/m2/gm2-compiler/M2SymInit.def:1:case statement has no matching selection 1 while /builddir/build/BUILD/gcc-13.2.1-20230728/obj-x86_64-redhat-linux/./gcc/gm2 -B/builddir/build/BUILD/gcc-13.2.1-20230728/obj-x86_64-redhat-linux/./gcc/ -c -O2 -fm2-pathname=m2iso -I. -Ilibm2iso -I/builddir/build/BUILD/gcc-13.2.1-20230728/gcc/m2/gm2-libs-iso -fm2-pathname=m2pim -I/builddir/build/BUILD/gcc-13.2.1-20230728/gcc/m2/gm2-libs -fiso -fextended-opaque -fm2-g -g -Wreturn-type -fcase -fm2-prefix=m2iso ../../../../libgm2/libm2iso/../../gcc/m2/gm2-libs-iso/SeqFile.mod -fPIC -DPIC -o .libs/SeqFile.o; echo $? 0 Shouldn't -Wall affect just warnings (without -Werror) and not whether compilation succeeds or fails?
