[FFmpeg-devel] [PATCH] build: make out-of-tree builds bit-identical to in-tree builds

[Henrik Gramner]

On Sat, Jan 23, 2016 at 12:41 PM, Hendrik Leppkes <h.leppkes at gmail.com> wrote:
> I did some testing why this breaks, and the reason is of course MSYS
> shenanigans.
>
> MSYS will automatically translate a UNIX-style path back to
> Windows-style when you pass it as a parameter, however, in this it
> fails because the syntax is "unconventional".
> MSVC uses the -Fo parameter for output files *without a space*, ie.
> /Fooutput.o, and MSYS doesn't replace the parameter then. Similar
> thing applies to the linker where this is -Fe instead.
>
> When building the original MSVC support this was already a problem
> with TMP files, which is why MSVC places tmp files into the build
> directory instead of a tmp folder with an absolute path.

Ah yes, you're correct. It's been some time since I messed with the
MSCV buildsystem in x264 so I didn't really remember all the details.

What we do in x264 is basically converting all paths to UNIX style (to
avoid some issues from mixing UNIX and Windows paths) and then change
them to be relative to the working directory instead of absolute. It
seems to work really well, at least I'm not aware of any case where it
breaks.