On Mon, May 6, 2013 at 10:41 AM, Erik Carstensen <address@hidden>
Are there any known problems or caveats with having relative paths with ..\ in VPATH on Windows?
I found the problem, there seems to be a limit in VPATH resolution of around 256 characters, where ..\ entries in the path are not collapsed. In my example, I ran make from c:\path\very-long-build-dir, and had ..\very-long-src-dir on VPATH; very-long-src-dir and very-long-build-dir were a bit over 200 characters together, so some but not all files in the src dir exceeded the length limit and were not found.
I don't know where this limit comes from; if it's a Windows limitation, there's not much we can do. In my example it would have helped to collapse the ..\:s in VPATH before resolving files, but it would just move the problem a few characters. I have solved it myself in my use case, by printing a warning when detecting dangerously long paths. I'm not sure if it would make sense for make itself to automatically warn on too long paths.