[Bug c++/77467] New: Segmentation fault with switch statement in constexpr function

["moritz at klammler dot eu" <gcc-bugzilla at gcc dot gnu dot org>]

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.