Re: some notes on installation with "-fnew-abi -fhonor-std"

[Alfred Minarik <a8601248@unet.univie.ac.at>]

Gabriel Dos_Reis wrote:

>gen-num-limits.cc only needs a "core" working g++, which is required
>if you want to install libstdc++ anyway. It uses features from the
>C-library and core C++ template machinery. That is all.

It is right that gen-num-limits.cc only NEEDS a core g++ to compile 
and no libstdc++ to link (therefore my remark about -nostdinc++ and 
a link step without -lstdc++), but we do not USE such a core g++:

lets take a closer look at mknumeric_limits
after writing out std_limits.h
g++ -o gen-num-limits $SRC_DIR/src/gen-num-limits.cc
is called, and this implies a linkstep with libstdc++
even if nothing is used from it
but in general there is no libstdc++ and the linker fails.

take a look at the ldd output: >ldd gen-num-limits
        libstdc++-libc6.0-1.so.2 =>
/home/am/gcc/egcs_current/usr/lib/libstdc++-libc6.0-1.so.2 (0x40000000)
        libm.so.6 => /lib/libm.so.6 (0x4004d000)
        libc.so.6 => /lib/libc.so.6 (0x40067000)
        /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x2aaaa000)

the easiest solution is to generate some dummy libstdc++.a (.so if
needed)
without any functions in dummypath and compile with g++ -Ldummypath
this could also work within configure.

Alfred