[NickGerleman]

Microsoft internally uses something pretty similar to Bazel. I'm not familiar enough with the two to fully understand motivations for the divergence. It supposedly initially ran poorly on Mac, just due to differences in what is cheap on different platforms. I wonder what kind of inherent performance differences you would find in something "Windows first" vs "Linux/MacOS first" https://github.com/microsoft/BuildXL

[EricBurnett]

The differences between bazel and BuildXL are less about platform and more about philosophy. Bazel is about opinionated builds - declare everything, and you get fast correct builds. Hard to adopt, but super powerful. BuildXL is more about meeting codebases where they are - take an existing msbuild|cmake|dscript build with its under-specified dependencies, and figure out how to parallelize it safely. This delivers quick wins, but comes with real costs as well (notably: no caching; labour-intensive magic to guess an initial seed of deps, with a performance cliff when something changes).

(Disclaimer: Googler, work closely with the bazel team. I like bazel; I like BuildXL for expanding the space of build ideas, but have long-term concerns it settles in a local maxima that'll be hard to get out of).

[m0zg]

I think there's nothing insurmountable in getting Bazel to work well on Windows. It's just a chicken and egg problem: few people use it there, so it's not up to par, so few people use it there because it's not up to par.