test tidy should ignore alternative build dir patterns

[richkadel]

I need to have multiple build directories, such as build,
build-fuchsia, and build-test. But when I'm uploading a change, I
run ./x.py test tidy, and if I have a build-something directory with
Rust sources, I git a bunch of formatting errors.

rustfmt.toml only ignores the directory named build.

This change extends the patterns to also ignore build-* and *-build.

As a rustc contributor, I not only build the rust compiler to develop
new features, but I also build alternative "distributions" (using
secondary *-config.toml files with different configurations),
including:

• To occasionally rebuild a version of the compiler that rust-analyzer
  can use to check source (which fixes issues in the VS Code UI, so
  changing and rebuilding the compiler does not break VS Code editing Rust
  code).
• To build custom distributions for Fuchsia
• To build test distributions when working on changes to bootstrap
  (e.g., when I recently added rust-demangler to distributions)

[rust-highfive]

r? @Mark-Simulacrum

(rust-highfive has picked a reviewer for you, use r? to override)

[jyn514]

@richkadel I'm curious - what's your workflow look like for those different build directories? Are you testing the same changes for multiple targets? Or are you switching between branches and you don't want to lose the build cache? For the second case I'd recommend git worktrees instead: https://rustc-dev-guide.rust-lang.org/building/suggested.html#working-on-multiple-branches-at-the-same-time

[richkadel]

It's the first case. For example, I normally build with debug, targeting only linux, and sometimes with a debug build of LLVM.

But when testing with Fuchsia, I have to use a very specific set of config.toml flags, targets, and install directories, etc. So I have a separate fuchsia-config.toml with those settings, and they build into fuchsia-build. As needed, I can make a rustc source change, rebuild and test with my normal config.toml, and when I'm ready, rebuild the fuchsia version and test in fuchsia.

[richkadel]

@Mark-Simulacrum - Any questions or concerns here?

(rust-highfive added you as reviewer. Let me know if you'd like someone else to review instead.)

Thanks!
Rich

[Mark-Simulacrum]

I usually take several days to get to an initial review - unfortunately accumulated some backlog which I've been processing over the last several days, so hopefully will get to this soon.

[richkadel]

No problem and no rush. Thanks for letting me know.

[Mark-Simulacrum]

@bors r+ rollup

Seems reasonable to me, thanks. Interesting pattern for sure!

[bors]

📌 Commit 79020a8 has been approved by Mark-Simulacrum