Problem
When running cargo build (or cargo check, cargo clippy), the $PATH env var contains ~/.cargo/bin twice. My $PATH contains it once (by sourcing ~/.cargo/env as per standard rustup install)
This addition to $PATH is mostly harmless, except when:
- A dependent package has a build.rs containing
cargo:rerun-if-env-changed=PATH
- User switches between running
cargo build and using something like rust-analyzer
The problem being:
- As user is editing,
rust-analyzer is building and writes the "non-duplicated" $PATH into the fingerprinting file
- User switches to terminal and runs
cargo build or similar, cargo adds the duplicated entry and the fingerprinter detects that $PATH changes and triggers a rebuild
- All downstream crates of the dependent package trbuild
- Switching back to rust-analyzer, it also rebuilds for the same reason
In short, the different $PATH causes lots of additional rebuilds (in some cases)
One example of this being pyo3:
PyO3/pyo3#1708
..which does have to re-run if $PATH changes, because a different Python interpreter might be added via a virtualenv
Steps (simpler)
Smallest reproduction case I can think of is:
dbr:~/pathexample$ cat Cargo.toml
[package]
name = "pathexample"
version = "0.1.0"
edition = "2018"
build = "build.rs"
[dependencies]
dbr:~/pathexample$ cat build.rs
fn main(){
dbg!(env!("PATH"));
panic!();
}
dbr:~/pathexample$ cargo build
Dupe path found /home/dbr/.cargo/bin
Compiling pathexample v0.1.0 (/home/dbr/pathexample)
error: failed to run custom build command for `pathexample v0.1.0 (/home/dbr/pathexample)`
Caused by:
process didn't exit successfully: `/home/dbr/pathexample/target/debug/build/pathexample-2395f9cd1cf04944/build-script-build` (exit code: 101)
--- stderr
[build.rs:2] env!("PATH") = "/home/dbr/.cargo/bin:/home/dbr/.cargo/bin:/usr/local/bin:/usr/bin:/bin:/usr/local/games:/usr/games"
thread 'main' panicked at 'explicit panic', build.rs:3:5
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
dbr:~/pathexample$ echo $PATH
/home/dbr/.cargo/bin:/usr/local/bin:/usr/bin:/bin:/usr/local/games:/usr/games
(Noting the [build.rs:2] env!("PATH") contains /home/dbr/.cargo/bin twice, whereas echo $PATH is "correct")
If I bypass rustup (..I think..) by setting $PATH to only include a specific toolchain, the duplication doesn't occur:
dbr:~/pathexample$ env PATH=/home/dbr/.rustup/toolchains/1.54-x86_64-unknown-linux-gnu/bin:/usr/local/bin:/usr/bin:/bin:/usr/local/games:/usr/games cargo build
Compiling pathexample v0.1.0 (/home/dbr/pathexample)
error: failed to run custom build command for `pathexample v0.1.0 (/home/dbr/pathexample)`
Caused by:
process didn't exit successfully: `/home/dbr/pathexample/target/debug/build/pathexample-875cafc10592a6c9/build-script-build` (exit status: 101)
--- stderr
[build.rs:2] env!("PATH") = "/home/dbr/.rustup/toolchains/1.54-x86_64-unknown-linux-gnu/bin:/usr/local/bin:/usr/bin:/bin:/usr/local/games:/usr/games"
thread 'main' panicked at 'explicit panic', build.rs:3:5
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
Steps (real world)
Larger repro is to:
- Make a simple crate with
pyo3 = "*" as a dependency
- run an editor with
rust-analyzer and make some trivial changes
- switch to a terminal and run the following:
CARGO_LOG=cargo::core::compiler::fingerprint=info cargo build
..and note the lines similar to:
INFO cargo::core::compiler::fingerprint] err: env var `PATH` changed: previously Some("/home/dbr/.cargo/bin:/usr/local/bin:/usr/bin:/bin:/usr/local/games:/usr/games"), now Some("/home/dbr/.cargo/bin:/home/dbr/.cargo/bin:/usr/local/bin:/usr/bin:/bin:/usr/local/games:/usr/games")
Possible Solution(s)
🤷
Notes
Output of rustup --version:
$ rustup --version
rustup 1.24.3 (ce5817a94 2021-05-31)
info: This is the version for the rustup toolchain manager, not the rustc compiler.
info: The currently active `rustc` version is `rustc 1.51.0 (2fd73fabe 2021-03-23)`
Output of rustup show:
$ rustup show
Default host: x86_64-unknown-linux-gnu
rustup home: /home/dbr/.rustup
installed toolchains
--------------------
stable-x86_64-unknown-linux-gnu
nightly-2021-04-15-x86_64-unknown-linux-gnu
nightly-2021-07-05-x86_64-unknown-linux-gnu
nightly-x86_64-unknown-linux-gnu
1.46-x86_64-unknown-linux-gnu
1.48-x86_64-unknown-linux-gnu
1.51-x86_64-unknown-linux-gnu (default)
1.53-x86_64-unknown-linux-gnu
1.54-x86_64-unknown-linux-gnu
installed targets for active toolchain
--------------------------------------
wasm32-unknown-unknown
x86_64-unknown-linux-gnu
active toolchain
----------------
1.51-x86_64-unknown-linux-gnu (default)
rustc 1.51.0 (2fd73fabe 2021-03-23)
Problem
When running
cargo build(orcargo check,cargo clippy), the$PATHenv var contains~/.cargo/bintwice. My$PATHcontains it once (by sourcing~/.cargo/envas per standard rustup install)This addition to
$PATHis mostly harmless, except when:cargo:rerun-if-env-changed=PATHcargo buildand using something likerust-analyzerThe problem being:
rust-analyzeris building and writes the "non-duplicated" $PATH into the fingerprinting filecargo buildor similar, cargo adds the duplicated entry and the fingerprinter detects that$PATHchanges and triggers a rebuildIn short, the different $PATH causes lots of additional rebuilds (in some cases)
One example of this being pyo3:
PyO3/pyo3#1708
..which does have to re-run if $PATH changes, because a different Python interpreter might be added via a virtualenv
Steps (simpler)
Smallest reproduction case I can think of is:
(Noting the
[build.rs:2] env!("PATH")contains/home/dbr/.cargo/bintwice, whereasecho $PATHis "correct")If I bypass rustup (..I think..) by setting $PATH to only include a specific toolchain, the duplication doesn't occur:
Steps (real world)
Larger repro is to:
pyo3 = "*"as a dependencyrust-analyzerand make some trivial changes..and note the lines similar to:
Possible Solution(s)
🤷
Notes
Output of
rustup --version:Output of
rustup show: