Constant-time tests on macOS

[sipa]

I noticed this in the CI output:

We are sunsetting support for Intel-based macOS instances! Please migrate before January 1st 2023.

[maflcko]

Is this fixed now?

[real-or-random]

from #1152:

It drops valgrind and the ctime tests on macOS, as valgrind simply isn't supported anymore there. We may recover some of that functionality by adding MSan (#1155) for memory-checking there, and adding ctime-using-mtime (TODO).

I think we should leave it open until this has been fixed.

• Enable MSan for MacOS
• Make the constant-time tests work on MSan

[real-or-random]

Oh, the valgrind fork now works on Ventura LouisBrunner/valgrind-macos#54 (comment) (except for memory leak tracking, which is still WIP but that shouldn't be required for our purposes.) So we should probably revert c0ae48c partly.

[hebasto]

• Enable MSan for MacOS

https://clang.llvm.org/docs/MemorySanitizer.html#supported-platforms:

MemorySanitizer is supported on the following OS:

• Linux
• NetBSD
• FreeBSD

[real-or-random]

Oh indeed, MSan doesn't work on macOS...

• Make the constant-time tests work on MSan

And this has been solved by #1169.

This means that there's nothing to do for us here except to wait for LouisBrunner/valgrind-macos#56. This will make it possible to run Valgrind on macOS again.

Leaving this open to track this.