http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49604
Summary: forward-declared enum in class scope is private in context of constexpr Product: gcc Version: 4.6.1 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ AssignedTo: unassig...@gcc.gnu.org ReportedBy: b.r.longb...@gmail.com Created attachment 24652 --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=24652 Minimal testcase If an enum is forward-declared as a public member of a class (but not a struct), and the values are defined afterward, then the enum values cannot be be used in the context of a constexpr: enum-broken.cpp:9:26: error: 'Foo::impl_t Foo::X' is private enum-broken.cpp:11:27: error: within this context (see attachment) Workaround: Use 'struct' instead of 'class'. What works: It works fine if 'struct' is used instead of 'class'. It works fine without the constexpr. It works fine if the enum values are defined in the declaration. It works find if the nested type is a struct with a static member. Versions: Using built-in specs. COLLECT_GCC=g++ COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-pc-linux-gnu/4.6.0/lto-wrapper Target: x86_64-pc-linux-gnu Configured with: /var/tmp/portage/sys-devel/gcc-4.6.0/work/gcc-4.6.0/configure --prefix=/usr --bindir=/usr/x86_64-pc-linux-gnu/gcc-bin/4.6.0 --includedir=/usr/lib/gcc/x86_64-pc-linux-gnu/4.6.0/include --datadir=/usr/share/gcc-data/x86_64-pc-linux-gnu/4.6.0 --mandir=/usr/share/gcc-data/x86_64-pc-linux-gnu/4.6.0/man --infodir=/usr/share/gcc-data/x86_64-pc-linux-gnu/4.6.0/info --with-gxx-include-dir=/usr/lib/gcc/x86_64-pc-linux-gnu/4.6.0/include/g++-v4 --host=x86_64-pc-linux-gnu --build=x86_64-pc-linux-gnu --disable-altivec --disable-fixed-point --without-ppl --without-cloog --enable-lto --disable-nls --with-system-zlib --disable-werror --enable-secureplt --enable-multilib --enable-libmudflap --disable-libssp --enable-libgomp --enable-cld --with-python-dir=/share/gcc-data/x86_64-pc-linux-gnu/4.6.0/python --enable-checking=release --disable-libgcj --enable-languages=c,c++,fortran --enable-shared --enable-threads=posix --enable-__cxa_atexit --enable-clocale=gnu --with-bugurl=http://bugs.gentoo.org/ --with-pkgversion='Gentoo 4.6.0 p1.2, pie-0.4.5' Thread model: posix gcc version 4.6.0 (Gentoo 4.6.0 p1.2, pie-0.4.5) Using built-in specs. COLLECT_GCC=g++ COLLECT_LTO_WRAPPER=/usr/lib/x86_64-linux-gnu/gcc/x86_64-linux-gnu/4.6.1/lto-wrapper Target: x86_64-linux-gnu Configured with: ../src/configure -v --with-pkgversion='Debian 4.6.1-1' --with-bugurl=file:///usr/share/doc/gcc-4.6/README.Bugs --enable-languages=c,c++,fortran,objc,obj-c++,go --prefix=/usr --program-suffix=-4.6 --enable-shared --enable-multiarch --with-multiarch-defaults=x86_64-linux-gnu --enable-linker-build-id --with-system-zlib --libexecdir=/usr/lib/x86_64-linux-gnu --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.6 --libdir=/usr/lib/x86_64-linux-gnu --enable-nls --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --enable-plugin --enable-objc-gc --with-arch-32=i586 --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 4.6.1 (Debian 4.6.1-1)