Non-standard builds, autoconf and gcc

[Todor Kondić]

I am trying to define a package that builds a source which has

a non-standard build procedure. It's a mix of autotools packages and something 
else. My first attempt was to use the trivial builder, pull in the 
gcc-toolchain along with autotools and use

this mixture for the parts where they can be used. The usual auto(re)conf et 
cetera method.

This unfortunately is one huge mess: even when i patch the  resulting configure 
script not to use hardwired /bin/sh /lib/cpp and such, gcc checks always fail. 
The glibc, gcc-toolchain-X.Y.Z and gcc-X.Y.Z(-lib), as well as binutils, all 
have overlapping, but not entirely same libraries, includes and gcc programs.

My first question,  if I am unable to simply use the gnu build system, but need 
autotools functionality, which packages should I pull in as native inputs for a 
regular C program? Is it the gcc-toolchain, or the hidden package gcc? 
Additionally, should I pull in binutils and glibc? The second question is, how 
to set the build environment? I realised that just installing the gcc-related 
packages does not necessarily mean that gcc knows about where the heck its 
brains and guts are. How to set COMPILER_PATH, LIBRARY_PATH and any other 
relevant environment variables?

Finally, can I work around these problems by calling some of the functionality 
of gnu-build-system from the builder?
Something like,

; trivial system on top-level
.
.
.
#:builder (... do preparatory stuff ...
           (with-directory-excursion "subpackage"
                (gnu-build-system-build-only ...)))
.
.
.

Cheers,

Todor