[Bug c++/54768] New: ICE when struct with anon union has constexpr ctor

[thomasmckee5 at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54768

             Bug #: 54768
           Summary: ICE when struct with anon union has constexpr ctor
    Classification: Unclassified
           Product: gcc
           Version: 4.6.3
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: thomasmckee5@gmail.com


Created attachment 28315
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=28315
Preprocessed source

On Ubuntu 12.04, the attached code causes an ICE. It seems that the combination
of an anonymous union and a constexpr constructor trigger the behviour.

$> g++ main.cpp -o cpptest -std=c++0x
main.cpp: In function ‘int main()’:
main.cpp:13:13:   in constexpr expansion of ‘temp.s::s(42)’
main.cpp:13:13: internal compiler error: in base_field_constructor_elt, at
cp/semantics.c:6558
Please submit a full bug report,
with preprocessed source if appropriate.
See <file:///usr/share/doc/gcc-4.6/README.Bugs> for instructions.
Preprocessed source stored into /tmp/ccrxnMUE.out file, please attach this to
your bugreport.

$> g++ -v
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/4.6/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu/Linaro
4.6.3-1ubuntu5' --with-bugurl=file:///usr/share/doc/gcc-4.6/README.Bugs
--enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr
--program-suffix=-4.6 --enable-shared --enable-linker-build-id
--with-system-zlib --libexecdir=/usr/lib --without-included-gettext
--enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.6
--libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu
--enable-libstdcxx-debug --enable-libstdcxx-time=yes --enable-gnu-unique-object
--enable-plugin --enable-objc-gc --disable-werror --with-arch-32=i686
--with-tune=generic --enable-checking=release --build=x86_64-linux-gnu
--host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 4.6.3 (Ubuntu/Linaro 4.6.3-1ubuntu5)