http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55607
Bug #: 55607 Summary: "undefined reference" with rvalue lambda at non-namespace scope Classification: Unclassified Product: gcc Version: 4.7.2 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ AssignedTo: unassig...@gcc.gnu.org ReportedBy: f.heckenb...@fh-soft.de Created attachment 28885 --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=28885 Reproducible test case Compiling the attached test case with g++ 4.7.2 (g++-4.7 -std=c++11 ud-lambda.cpp) gives the following error: /tmp/ccNp8EwS.o: In function `foo::bar()::{lambda()#1}::operator void (*)()() const': ud-lambda.cpp:(.text._ZZN3foo3barEvENKUlvE_cvPFvvEEv[_ZZN3foo3barEvENKUlvE_cvPFvvEEv]+0x4): undefined reference to `foo::bar()::{lambda()#1}::_FUN()' collect2: error: ld returned 1 exit status The error did not occur with 4.7.0. The demo program shows two variants using "#if" (since I apparently can't add two separate attachments here). Both show the same problem. I'm not sure which one is more useful. The important points are that a lambda is used as an rvalue -- in the first case due to the "+", in the second case due to the conversion to a function pointer -- and that it's done in a nested scope (here, struct foo). I suppose the test case is correct, but in case it's not, I'd expect a compiler error, not a link-time undefined reference. % g++-4.7 -v COLLECT_GCC=g++-4.7 COLLECT_LTO_WRAPPER=/usr/lib/gcc/i486-linux-gnu/4.7/lto-wrapper Target: i486-linux-gnu Configured with: ../src/configure -v --with-pkgversion='Debian 4.7.2-4' --with-bugurl=file:///usr/share/doc/gcc-4.7/README.Bugs --enable-languages=c,c++,go,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-4.7 --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++/4.7 --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 --enable-targets=all --with-arch-32=i586 --with-tune=generic --enable-checking=release --build=i486-linux-gnu --host=i486-linux-gnu --target=i486-linux-gnu Thread model: posix gcc version 4.7.2 (Debian 4.7.2-4)