https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77467
Bug ID: 77467 Summary: Segmentation fault with switch statement in constexpr function Product: gcc Version: 6.1.1 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: moritz at klammler dot eu Target Milestone: --- Compiling the following file causes GCC to segfault. (I have version 6.1.1 but according to Wandbox HEAD is also affected.) # 1 "raise.cxx" # 1 "<built-in>" # 1 "<command-line>" # 1 "/usr/include/stdc-predef.h" 1 3 4 # 1 "<command-line>" 2 # 1 "raise.cxx" constexpr int raise(const int x, const unsigned n) noexcept { switch (n) { case 0: return 1; case 1: return x; default: const auto m = (n >> 1); const auto y = raise(x, m); return ((m << 1) == n) ? y * y : x * y * y; } } static_assert(raise(3, 2) == 9, ""); static_assert(raise(2, 3) == 8, ""); As far as I can tell, the program is conforming C++14. Clang compiles it with no errors. Here is the detailed output. Using built-in specs. COLLECT_GCC=g++ Target: x86_64-pc-linux-gnu Configured with: /build/gcc/src/gcc/configure --prefix=/usr --libdir=/usr/lib --libexecdir=/usr/lib --mandir=/usr/share/man --infodir=/usr/share/info --with-bugurl=https://bugs.archlinux.org/ --enable-languages=c,c++,ada,fortran,go,lto,objc,obj-c++ --enable-shared --enable-threads=posix --enable-libmpx --with-system-zlib --with-isl --enable-__cxa_atexit --disable-libunwind-exceptions --enable-clocale=gnu --disable-libstdcxx-pch --disable-libssp --enable-gnu-unique-object --enable-linker-build-id --enable-lto --enable-plugin --enable-install-libiberty --with-linker-hash-style=gnu --enable-gnu-indirect-function --disable-multilib --disable-werror --enable-checking=release Thread model: posix gcc version 6.1.1 20160802 (GCC) COLLECT_GCC_OPTIONS='-std=c++14' '-c' '-v' '-save-temps' '-Wall' '-Wextra' '-Werror' '-Wpedantic' '-shared-libgcc' '-mtune=generic' '-march=x86-64' /usr/lib/gcc/x86_64-pc-linux-gnu/6.1.1/cc1plus -E -quiet -v -D_GNU_SOURCE raise.cxx -mtune=generic -march=x86-64 -std=c++14 -Wall -Wextra -Werror -Wpedantic -fpch-preprocess -o raise.ii ignoring nonexistent directory "/usr/lib/gcc/x86_64-pc-linux-gnu/6.1.1/../../../../x86_64-pc-linux-gnu/include" #include "..." search starts here: #include <...> search starts here: /usr/lib/gcc/x86_64-pc-linux-gnu/6.1.1/../../../../include/c++/6.1.1 /usr/lib/gcc/x86_64-pc-linux-gnu/6.1.1/../../../../include/c++/6.1.1/x86_64-pc-linux-gnu /usr/lib/gcc/x86_64-pc-linux-gnu/6.1.1/../../../../include/c++/6.1.1/backward /usr/lib/gcc/x86_64-pc-linux-gnu/6.1.1/include /usr/local/include /usr/lib/gcc/x86_64-pc-linux-gnu/6.1.1/include-fixed /usr/include End of search list. COLLECT_GCC_OPTIONS='-std=c++14' '-c' '-v' '-save-temps' '-Wall' '-Wextra' '-Werror' '-Wpedantic' '-shared-libgcc' '-mtune=generic' '-march=x86-64' /usr/lib/gcc/x86_64-pc-linux-gnu/6.1.1/cc1plus -fpreprocessed raise.ii -quiet -dumpbase raise.cxx -mtune=generic -march=x86-64 -auxbase raise -Wall -Wextra -Werror -Wpedantic -std=c++14 -version -o raise.s GNU C++14 (GCC) version 6.1.1 20160802 (x86_64-pc-linux-gnu) compiled by GNU C version 6.1.1 20160802, GMP version 6.1.1, MPFR version 3.1.4-p1, MPC version 1.0.3, isl version 0.15 GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072 GNU C++14 (GCC) version 6.1.1 20160802 (x86_64-pc-linux-gnu) compiled by GNU C version 6.1.1 20160802, GMP version 6.1.1, MPFR version 3.1.4-p1, MPC version 1.0.3, isl version 0.15 GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072 Compiler executable checksum: a737bda7bba379565b9dc4d86a8d469f raise.cxx:18:20: in constexpr expansion of ‘raise(3, 2u)’ raise.cxx:18:30: internal compiler error: Segmentation fault static_assert(raise(3, 2) == 9, ""); ^ Please submit a full bug report, with preprocessed source if appropriate. See <https://bugs.archlinux.org/> for instructions. I wasn't able to find this problem already reported but then again, I didn't really know what to search for. Thanks for looking into it.