cc9a4a2134
Consistently unset RUSTC_BOOTSTRAP when compiling bootstrap
Since https://github.com/rust-lang/rust/pull/113906, all x.py invocations performed by rust-analyzer have RUSTC_BOOTSTRAP=1 set. This was to fix https://github.com/rust-lang/rust/issues/112391#issuecomment-1597224941 — rust-analyzer uses some default cargo from the system when fetching workspace layout, and the standard library uses some unstable cargo feature, so x.py would previously fail if the system toolchain wasn't nightly.
82e1608dfa/library/std/Cargo.toml (L1)
This PR changes x.py to cancel out this RUSTC_BOOTSTRAP=1 when compiling bootstrap. It will only remain set when running the compiled bootstrap executable. This fixes spurious bootstrap rebuilds in the event that a rust-analyzer x.py invocation is alternated with someone running x.py themself on the command line, if any dependency of bootstrap looks at `option_env!("RUSTC_BOOTSTRAP")`, which is the case since https://github.com/rust-lang/rust/pull/119654.
**Before:**
```console
$ RUSTC_BOOTSTRAP=1 ./x.py check library/core
Building bootstrap
Compiling proc-macro2 v1.0.76
Compiling quote v1.0.35
Compiling syn v2.0.48
Compiling clap_derive v4.4.7
Compiling serde_derive v1.0.195
Compiling clap v4.4.13
Compiling clap_complete v4.4.6
Compiling build_helper v0.1.0
Compiling bootstrap v0.0.0
Finished dev [unoptimized] target(s) in 6.31s
Checking stage0 library artifacts {core} (x86_64-unknown-linux-gnu)
Finished release [optimized] target(s) in 0.23s
Build completed successfully in 0:00:07
$ ./x.py check library/core
Building bootstrap
Compiling proc-macro2 v1.0.76
Compiling quote v1.0.35
Compiling syn v2.0.48
Compiling clap_derive v4.4.7
Compiling serde_derive v1.0.195
Compiling clap v4.4.13
Compiling clap_complete v4.4.6
Compiling build_helper v0.1.0
Compiling bootstrap v0.0.0
Finished dev [unoptimized] target(s) in 5.30s
Checking stage0 library artifacts {core} (x86_64-unknown-linux-gnu)
Finished release [optimized] target(s) in 0.25s
Build completed successfully in 0:00:06
```
**After:**
```console
$ RUSTC_BOOTSTRAP=1 ./x.py check library/core
Building bootstrap
Finished dev [unoptimized] target(s) in 0.06s
Checking stage0 library artifacts {core} (x86_64-unknown-linux-gnu)
Finished release [optimized] target(s) in 0.14s
Build completed successfully in 0:00:01
$ ./x.py check library/core
Building bootstrap
Finished dev [unoptimized] target(s) in 0.04s
Checking stage0 library artifacts {core} (x86_64-unknown-linux-gnu)
Finished release [optimized] target(s) in 0.13s
Build completed successfully in 0:00:01
```
This directory contains some source code for the Rust project, including:
- The bootstrapping build system
- Various submodules for tools, like cargo, tidy, etc.
For more information on how various parts of the compiler work, see the rustc dev guide.