[Bug c++/53761] New: ICE (only with C++) on incorrect transparent union (first field has floating point type)

[br+gcc at waldteufel dot eu]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53761

             Bug #: 53761
           Summary: ICE (only with C++) on incorrect transparent union
                    (first field has floating point type)
    Classification: Unclassified
           Product: gcc
           Version: 4.7.1
            Status: UNCONFIRMED
          Severity: minor
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: br+gcc@waldteufel.eu


While compiling

typedef union {
   double x;
} __attribute__(( __transparent_union__ )) example_t;

void fail(example_t x) { }

int main() {
   example_t x;
   fail(x);
}

as C code results in a warning message (see below for detailed system
information)

> gcc fail.c
fail.c:1:9: warning: union cannot be made transparent [enabled by default]

compiling the same code as C++ results in an ICE

> g++ -v fail.cc
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-unknown-linux-gnu/4.7.1/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: /build/src/gcc-4.7.1/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 --with-system-zlib --enable-__cxa_atexit
--disable-libunwind-exceptions --enable-clocale=gnu --disable-libstdcxx-pch
--enable-libstdcxx-time --enable-gnu-unique-object --enable-linker-build-id
--with-ppl --enable-cloog-backend=isl --enable-lto --enable-gold
--enable-ld=default --enable-plugin --with-plugin-ld=ld.gold
--with-linker-hash-style=gnu --disable-multilib --disable-libssp
--disable-build-with-cxx --disable-build-poststage1-with-cxx
--enable-checking=release
Thread model: posix
gcc version 4.7.1 (GCC) 
COLLECT_GCC_OPTIONS='-v' '-shared-libgcc' '-mtune=generic' '-march=x86-64'
 /usr/lib/gcc/x86_64-unknown-linux-gnu/4.7.1/cc1plus -quiet -v -D_GNU_SOURCE
fail.cc -quiet -dumpbase fail.cc -mtune=generic -march=x86-64 -auxbase fail
-version -o /tmp/cc6IkFB2.s
GNU C++ (GCC) version 4.7.1 (x86_64-unknown-linux-gnu)
    compiled by GNU C version 4.7.1, GMP version 5.0.5, MPFR version 3.1.0-p10,
MPC version 0.9
GGC heuristics: --param ggc-min-expand=97 --param ggc-min-heapsize=126590
ignoring nonexistent directory
"/usr/lib/gcc/x86_64-unknown-linux-gnu/4.7.1/../../../../x86_64-unknown-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
 /usr/lib/gcc/x86_64-unknown-linux-gnu/4.7.1/../../../../include/c++/4.7.1

/usr/lib/gcc/x86_64-unknown-linux-gnu/4.7.1/../../../../include/c++/4.7.1/x86_64-unknown-linux-gnu

/usr/lib/gcc/x86_64-unknown-linux-gnu/4.7.1/../../../../include/c++/4.7.1/backward
 /usr/lib/gcc/x86_64-unknown-linux-gnu/4.7.1/include
 /usr/local/include
 /usr/lib/gcc/x86_64-unknown-linux-gnu/4.7.1/include-fixed
 /usr/include
End of search list.
GNU C++ (GCC) version 4.7.1 (x86_64-unknown-linux-gnu)
    compiled by GNU C version 4.7.1, GMP version 5.0.5, MPFR version 3.1.0-p10,
MPC version 0.9
GGC heuristics: --param ggc-min-expand=97 --param ggc-min-heapsize=126590
Compiler executable checksum: ed88b587bcb9a173af71789c9d103676
fail.cc: In function 'int main()':
fail.cc:9:11: internal compiler error: in convert_move, at expr.c:325
Please submit a full bug report,
with preprocessed source if appropriate.
See <https://bugs.archlinux.org/> for instructions.