These environment variables are used by d2c:
The root of the installed Gwydion tree. In the default configuration, this defaults to /usr/local on Unix and c:\dylan on win32. This variable in turn establishes the defaults for DYLANPATH and the platforms.descr file.
The search path for Dylan libraries. Directories in the DYLANPATH are searched after any directories specified by explicit -L options. If not set, this defaults to ".:$DYLANDIR/lib/dylan" (".;%DYLANDIR%\lib\dylan" on Win32). If set, the value must include the directory where the Dylan library is to be found.
d2c expects to find make and the C compiler in PATH. On Unix we use the GNU tools gmake, gcc, and ld. Other compilers can work, but at a minimum this requires a new platform description in $DYLANDIR/share/dylan/platforms.descr. You must also have some of the GNU-win32 tools to run d2c on Windows, though make and Visual C++ are normally used for compilation. To build d2c, you also need perl and the various scripts in the tools directory.
The GNU assembler must be used in conjunction with the generated code from gcc. If you somehow end up running the HP/UX as with gcc, it will produce many errors about STAB entries, etc.
This variable holds the flags passed to the C compiler. The default is platform-specific, but always includes -I$DYLANDIR/include. If you do set this variable, you must also specify the Dylan system include directory. The default optimization flags for gcc are -O2 -fomit-frame-pointer -fno-strict-aliasing. Leaving out the optimize flags will speed compilation at the cost of runtime speed.