In the past (at least it worked for me in 4.9) it was possible to use the
uninstalled C & C++ compilers to build another compiler, using the just built
compilers. Useful if you want to build e.g. libgccjit in a second step without
bootstrapping again. This doesn't seem to work anymore with 5. At least I can't
get it working by removing the system c++ and g++ after the build of the first
compiler and then building as
CC=$(builddir)/gcc/xgcc -B$(builddir)/gcc/
CXX=$(builddir)/gcc/xg++ -B$(builddir)/gcc/ \
-I$(builddir)/$(TARGET_ALIAS)/libstdc++-v3/include \
-I$(builddir)/$(TARGET_ALIAS)/libstdc++-v3/include/$(TARGET_ALIAS)
and the next build (without bootstrapping) with these values. Did somebody got
this working? Sometimes it looks like gcc is built using the C compiler,
sometimes it doesn't find the "new" header, and probably won't find the
libstdc++ library later. Not setting CXX seems to silently use the g++ system
compiler if it exists.
Matthias
