So I took a look at the code now. Moveing from 2K (0x501) to XP (0x501) APIs fixed the IPv6 problems.
The next problem is that ssize_t is not in the standard and is apparently not a thing in the MS SDK. Hacked around that by defining it as an int just to get past it.
The problem after that is that las.c breaks the preprocessor. The two ifdef PIKE_DEBUG blocks inside the WALK_NONFREE_BLOCKS macro does not get parsed, which obviously leaves an uncompilable mess. Bodged around that by simply removing the debug code.
Next up was some broken prototypes. The linker is not to happy about multiple defintions that don't match exactly and use DLL export.
And then we come to the modules:
#### Making static: modules/system make[3]: Circular include <- include dependency dropped. /home/builder/dists/Pike-v7.9-snapshot/bin/smartlink rntcl -DPIKE_SRC_ROOT="/home/builder/dists/Pike-v7.9-snapshot" -I. -I/home/builder/dists/Pike-v7.9-snapshot/src -DPIKE_CORE -g -MD -O2 -LARGEADDRESSAWARE main.o language.o security.o bignum.o pike_cpulib.o interpret.o constants.o cpp.o fdlib.o cyclic.o array.o backend.o callback.o encode.o docode.o dynamic_buffer.o dynamic_load.o error.o fd_control.o fsort.o gc.o hashtable.o lex.o multiset.o signal_handler.o pike_search.o pike_types.o pike_embed.o mapping.o block_allocator.o pike_memory.o module_support.o pikecode.o object.o opcodes.o operators.o pike_float.o port.o program.o rbtree.o rusage.o sprintf.o sscanf.o stralloc.o stuff.o threads.o version.o queue.o builtin.o iterators.o svalue.o las.o builtin_functions.o peep.o malloc.o crypt.o tmodule.o \ `cat modules/linker_options ` \ -lshell32 -lkernel32 -lws2_32 -ladvapi32 pike_icon.res -o pike.exe Creating library pike.exe.lib and object pike.exe.exp cl : Command line warning D9024 : unrecognized source file type 'B:\dists\Pike-v7.9-snapshot\build\windows_xp-5.1.2600-i386\modules\Gmp\module.a', object file assumed cl : Command line warning D9024 : unrecognized source file type 'B:\dists\Pike-v7.9-snapshot\build\windows_xp-5.1.2600-i386\modules_Stdio\module.a', object file assumed cl : Command line warning D9024 : unrecognized source file type 'B:\dists\Pike-v7.9-snapshot\build\windows_xp-5.1.2600-i386\modules_math\module.a', object file assumed cl : Command line warning D9024 : unrecognized source file type 'B:\dists\Pike-v7.9-snapshot\build\windows_xp-5.1.2600-i386\modules\system\module.a', object file assumed #### Making dynamic: modules/CommonLog make[6]: *** No rule to make target `/home/builder/dists/Pike-v7.9-snapshot/build/windows_xp-5.1.2600-i386/pike.lib', needed by `module.so'. Stop. make[5]: *** [all] Error 2 make[4]: *** [CommonLog] Error 1 make[3]: *** [dynamic_module_objects] Error 1 make[2]: *** [module_objects] Error 2 make[1]: *** [_make_in_builddir] Error 2 make: *** [wix] Error 2
Which is where I will stop for tonight.