gcc -dumpmachine

[mintty]

gcc -dumpmachine used to report x86_64-pc-msys;
this was recently changed to report x86_64-pc-cygwin

This disturbs multi-platform build processes. Was there a reason for the change?

[ognevny]

such change was planned long ago: https://www.msys2.org/wiki/Devtopics. shortly it's a part of unifying msys2 with cygwin

just wondering, why do you need a separate msys platform?

[mintty]

This is about building mintty. There are a few compile-time difference, e.g. path prefix handling, depending on #define __MSYS__. Compiled sources should not be mixed and thus confused so there are platform-dependent build target directories. I currently derivce them from gcc -dumpmachine. I could change that to look at uname but that would not work (for other projects) with cross-compilation.
Anyway, since gcc is different from the cygwin build (even if it were only about setting __MSYS__), I think despite any unification it would still be useful to indicate that on option -dumpmachine.

[lazka]

• https://www.msys2.org/news/#2025-02-14-moving-msys2-closer-to-cygwin
• https://www.msys2.org/news/#2025-06-20-replacing-x86_64-pc-msys-with-x86_64-pc-cygwin

Compiled sources should not be mixed and thus confused so there are platform-dependent build target directories.

Maybe you can make your build dir configurable instead?

[mintty]

Well, as described further above, I have it auto-configurable, using just gcc -dumpmachine, which I need to change now.
However, for some use cases (cross-compilation) this may not be sufficient, so my suggestion is to keep the distinct output on that option. Is there anything substantial that would count against it?

[lazka]

Is there anything substantial that would count against it?

I guess the main thing is that it's documented to print the target triplet, which is "x86_64-pc-cygwin" now.

Well, as described further above, I have it auto-configurable, using just gcc -dumpmachine, which I need to change now.

What's the problem with the build dir being called cygwin?

[mintty]

What's the problem with the build dir being called cygwin?

The problem is a common build dir for both cygwin and msys. Some compilates are different, e.g. about /cygwin prefix handling for copy/paste which is just / in msys. If I mix up *.o files in the same directory, the result may become inconsistent and I may end up bundling wrong binaries, for example for wsltty. If you only build for one target, there's no problem.

[lazka]

I understand that the current way worked nicely for you until now, but other build systems (autotools, meson, cmake) just solve this by allowing out-of-tree builds, and you could easily support that too.