Rollup merge of #127958 - jieyouxu:compiletest-rmake-cleanup, r=Kobzol

Cleanup rmake.rs setup in compiletest

While debugging rmake.rs tests I realized that the rmake.rs setup itself in compiletest is very messy and confused. Now that I know some of the bootstrap steps and the rmake.rs tests themselves better, I realized there are cleanups that are possible:

- Rework how `source_root` and `build_root` are calculated. They should now be less fragile then before.
- Shuffle around path calculations to make them more logically grouped and closer to eventual use site(s).
- Cleanup executable extension calculation with `std::env::consts::EXE_EXTENSION`.
- Cleanup various dylib search path handling: renamed variables to better reflect their purpose, minimized mutability scope of said variables.
- Prune useless env vars passed to both `rustc` and recipe binary commands.
- Vastly improve the documentation for the setup of rmake.rs tests, including assumed bootstrap-provided build layouts, rmake.rs test layout, dylib search paths, intended purpose of passed env vars and the `COMPILETEST_FORCE_STAGE0=1 ./x test run-make --stage 0` stage0 sysroot special handling.

This PR is best reviewed commit-by-commit.

Fixes https://github.com/rust-lang/rust/issues/127920.

r? bootstrap (or Kobzol, or Mark, or T-compiler)

try-job: aarch64-apple
try-job: armhf-gnu
try-job: dist-x86_64-linux
try-job: test-various
try-job: x86_64-mingw
try-job: x86_64-msvc
try-job: x86_64-gnu-llvm-18
tree: 85e4128318d372551db19fa4adb91f04d91e5da7
  1. .github/
  2. .reuse/
  3. compiler/
  4. library/
  5. LICENSES/
  6. src/
  7. tests/
  8. .clang-format
  9. .editorconfig
  10. .git-blame-ignore-revs
  11. .gitattributes
  12. .gitignore
  13. .gitmodules
  14. .ignore
  15. .mailmap
  16. Cargo.lock
  17. Cargo.toml
  18. CODE_OF_CONDUCT.md
  19. config.example.toml
  20. configure
  21. CONTRIBUTING.md
  22. COPYRIGHT
  23. INSTALL.md
  24. LICENSE-APACHE
  25. LICENSE-MIT
  26. README.md
  27. RELEASES.md
  28. rust-bors.toml
  29. rustfmt.toml
  30. triagebot.toml
  31. x
  32. x.ps1
  33. x.py
README.md

Website | Getting started | Learn | Documentation | Contributing

This is the main source code repository for Rust. It contains the compiler, standard library, and documentation.

Why Rust?

  • Performance: Fast and memory-efficient, suitable for critical services, embedded devices, and easily integrate with other languages.

  • Reliability: Our rich type system and ownership model ensure memory and thread safety, reducing bugs at compile-time.

  • Productivity: Comprehensive documentation, a compiler committed to providing great diagnostics, and advanced tooling including package manager and build tool (Cargo), auto-formatter (rustfmt), linter (Clippy) and editor support (rust-analyzer).

Quick Start

Read “Installation” from The Book.

Installing from Source

If you really want to install from source (though this is not recommended), see INSTALL.md.

Getting Help

See https://www.rust-lang.org/community for a list of chat platforms and forums.

Contributing

See CONTRIBUTING.md.

License

Rust is primarily distributed under the terms of both the MIT license and the Apache License (Version 2.0), with portions covered by various BSD-like licenses.

See LICENSE-APACHE, LICENSE-MIT, and COPYRIGHT for details.

Trademark

The Rust Foundation owns and protects the Rust and Cargo trademarks and logos (the “Rust Trademarks”).

If you want to use these names or brands, please read the media guide.

Third-party logos may be subject to third-party copyrights and trademarks. See Licenses for details.