I had a stab at compiling ECL using 64 bit Windows (VC8) compiler. The version is 0.9i from the tarball I think.
Have ECL_THREADS = 1.
I added a few compiler flags to both Makefile and gmp/Makefile (see below) to shut VC8 up a bit.
 
The error that stops the compiler is:
error C2491: 'strnlen' : definition of dllimport function not allowed
Anyone tried this ?
 
 
..\..\src\gmp\printf\printffuns.c(65) : warning C4267: '=' : conversion from 'size_t' to 'int', possible loss of data
        cl -c -EHsc -nologo -MD /W3 /Ox -DWIN32_LEAN_AND_MEAN -D_CRT_SECURE_NO_DEPRECATE -D_CRT_NONONSTDC_NO_DEPRECATE /
I "." /I ..\..\src\gmp /I "..\..\src\gmp\mpn\generic" /D "WIN32" /D "NDEBUG" /D "_LIB" /D "_WIN32" /D "_MBCS" /Foprintf\
repl-vsnprintf.obj ..\..\src\gmp\printf\repl-vsnprintf.c
repl-vsnprintf.c
..\..\src\gmp\printf\repl-vsnprintf.c(66) : error C2491: 'strnlen' : definition of dllimport function not allowed
..\..\src\gmp\printf\repl-vsnprintf.c(289) : warning C4267: '=' : conversion from 'size_t' to 'int', possible loss of da
ta
..\..\src\gmp\printf\repl-vsnprintf.c(382) : warning C4267: 'return' : conversion from 'size_t' to 'int', possible loss
of data
NMAKE : fatal error U1077: '"D:\Program Files (x86)\Microsoft Visual Studio 8\VC\BIN\x86_amd64\cl.EXE"' : return code '0
x2'
Stop.
NMAKE : fatal error U1077: '"D:\Program Files (x86)\Microsoft Visual Studio 8\VC\BIN\nmake.exe"' : return code '0x2'
Stop.
 
Cheers
Dean