[Bug c++/80908] New: [c++1z] ICE on instantiating a template deducing the noexcept-ness of a function pointer

[hafnermorris at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80908

            Bug ID: 80908
           Summary: [c++1z] ICE on instantiating a template deducing the
                    noexcept-ness of a function pointer
           Product: gcc
           Version: 7.1.1
            Status: UNCONFIRMED
          Keywords: ice-on-invalid-code
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hafnermorris at gmail dot com
  Target Milestone: ---

Created attachment 41433
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=41433&action=edit
Minimal example code

The following incorrect code causes an internal compiler error in C++17 mode
starting with gcc 7.1.0:

template<typename T>
struct S;

template<bool IsNoexcept>
struct S<void(*)() noexcept(IsNoexcept)> {
        S() {}
};

void f() {}

int main() {
        S<decltype(&f)> {};
}

The code is probably incorrect, because it tries to deduce noexcept(bool) and
is rejected by clang in C++17 mode.

Compiler invocation: g++ -std=c++1z example.cpp 
example.cpp: In instantiation of ‘S<void (*)() noexcept (IsNoexcept)>::S()
[with bool IsNoexcept = false]’:
example.cpp:12:19:   required from here
example.cpp:6:2: internal compiler error: Segmentation fault
  S() {}
  ^
Please submit a full bug report,
with preprocessed source if appropriate.
See <https://bugs.archlinux.org/> for instructions.

gcc -v:
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-pc-linux-gnu/7.1.1/lto-wrapper
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 7.1.1 20170516 (GCC) 


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