Ignore patching Mach-O files if not running on macOS

[chrisburr]

As found in conda-forge/cmake-feedstock#115 (comment) the Linux CMake build produces a Mach-O binary which then triggers this assertion and causes the build to fail.

This is a regression in 3.18 as this function used to never be called on other platforms: https://github.com/conda/conda-build/pull/3808/files#diff-60400bbbdb51124a0a8a06ca17ecec5cL1105

cc @jakirkham

[mingwandroid]

Would removing the assert and building install_name_tool in Linux not be a better approach here?

[jakirkham]

This seems pretty clean and simple to me. Thanks @chrisburr 😀

Why do we need install_name_tool on Linux?

[mingwandroid]

Because as seems to be the case here we are building broken macOS software on Linux.

[chrisburr]

Would removing the assert and building install_name_tool in Linux not be a better approach here?

Definitely and conda-forge already has it in cctools, though the binaries are prefixed like x86_64-apple-darwin13.4.0-otool and x86_64-apple-darwin13.4.0-install_name_tool. I'm not sure how best to handle the prefix? Also what if a Mach-O binary appears during a build on Windows?

As it stands the import is commented out so other changes will also be needed:

conda-build/conda_build/post.py

Lines 39 to 40 in 79da171

	if sys.platform == 'darwin':
	from conda_build.os_utils import macho

Because as seems to be the case here we are building broken macOS software on Linux.

In the case of CMake it's actually okay as the binary in question doesn't need to be modified to make it relocatable so we're not actually building broken software. That said, there is the potential to but I think it's still better than the current situation where it's impossible to build CMake.

[mingwandroid]

Thanks!

[jakirkham]

Thanks Chris and Ray! 😄

[mrakitin]

I would like to thank @chrisburr for the fix as I was struggling with that exact issue today a lot (e.g., in this build).

[mrakitin]

Is it a standard style (2 blank space indents) here in conda-build? I saw 4 space indents in many other codes of the code base.

[jakirkham]

It should be 4 spaces. Can you please send a PR to fix it?

[jjhelmus]

PR #3925 adjusts the indentation and fixes another bug introduced here.

[mrakitin]

Thank you!

[github-actions]

Hi there, thank you for your contribution!

This pull request has been automatically locked because it has not had recent activity after being closed.

Please open a new issue or pull request if needed.

Thanks!