pingus fails to build, maybe since the last core update:

--8<---------------cut here---------------start------------->8---
g++ -o build/src/pingus/screens/demo_session.o -c -O2 -s -std=c++0x -isystem/gnu/store/3snpwk7jl8i125bhiilvk9scqc4mnsx7-libpng-1.6.37/include/libpng16 -DVERSION="\"0.7.6\"" -DHAVE_OPENGL=1 -DHAVE_LINUXEVDEV=1 -D_GNU_SOURCE=1 -D_REENTRANT -DHAVE_ICONV_CONST -DICONV_CONST= -Ibuild/src -Isrc -I/gnu/store/3zh2m96050jbd4c7g2qc4mg2jq02zgd8-sdl-1.2.15/include/SDL -I/gnu/store/p04y598xbcpi11xw3vx77h6klnmrmm17-sdl-image-1.2.12/include/SDL -I/gnu/store/98q06cqxskclzgs0wislfnjg1n3gsdbl-sdl-mixer-1.2.12/include/SDL -Ibuild -I. -Ibuild/src -Isrc -Ibuild/external/tinygettext -Iexternal/tinygettext src/pingus/screens/demo_session.cpp
src/pingus/screens/demo_session.cpp:40:8: error: ‘function’ in namespace ‘std’ does not name a template type
   std::function<void(void)> callback;
        ^~~~~~~~
--8<---------------cut here---------------end--------------->8---

-- 
Pierre Neidhardt
https://ambrevar.xyz/