The Rust libs team quietly decided to start blocking -Zunstable-options in Rust 1.70 outside of nightly builds. Rust 1.70 is now in beta.
rust-lang/rust#109044
$ cargo +beta test -- -Zunstable-options --format json
Finished test [unoptimized + debuginfo] target(s) in 0.22s
Running unittests src/lib.rs ([removed])
error: the option `Z` is only accepted on the nightly compiler
error: test failed, to rerun pass `--lib`
Arguably cargo2unit users were playing with fire by taking a dependency on this... but nonetheless this will strand users on 1.69 who depend on JSON output in their CI builds.
Luckily, it seems that setting RUSTC_BOOTSTRAP=1 in the environment before launching the test will work around this. This seems strictly worse than the status quo since it allows other Rust unstable features to be used as well. Oh well.
Perhaps the README should be updated to reflect this.
The Rust libs team quietly decided to start blocking
-Zunstable-optionsin Rust 1.70 outside of nightly builds. Rust 1.70 is now in beta.rust-lang/rust#109044
Arguably cargo2unit users were playing with fire by taking a dependency on this... but nonetheless this will strand users on 1.69 who depend on JSON output in their CI builds.
Luckily, it seems that setting
RUSTC_BOOTSTRAP=1in the environment before launching the test will work around this. This seems strictly worse than the status quo since it allows other Rust unstable features to be used as well. Oh well.Perhaps the README should be updated to reflect this.