Add the -Zfeature=foo unstable rustc option

This PR adds a new unstable option to `rustc`: `-Zfeature=foo`. The option can be used to enable nightly features from the CLI, and it's meant to be used by tools like Crater to try enabling features without changing the crate's source code.

The exact reason I need this is to implement "edition runs" in Crater: we need to add the preview feature flag to every crate, and editing the crates' source code on the fly might produce unexpected results, while a compiler flag is more reliable. Obviously this won't be stabilized in the future.

cc rust-lang/crater#282 @Mark-Simulacrum

Add the -Zcrate-attr=foo unstable rustc option

This PR adds a new unstable option to `rustc`: `-Zcrate-attr=foo`. The option can be used to inject crate-level attributes from the CLI, and it's meant to be used by tools like Crater that needs to add their own attributes to a crate without changing the source code.

The exact reason I need this is to implement "edition runs" in Crater: we need to add the preview feature flag to every crate, and editing the crates' source code on the fly might produce unexpected results, while a compiler flag is more reliable.

cc rust-lang/crater#282 @Mark-Simulacrum

Add the -Zcrate-attr=foo unstable rustc option

This PR adds a new unstable option to `rustc`: `-Zcrate-attr=foo`. The option can be used to inject crate-level attributes from the CLI, and it's meant to be used by tools like Crater that needs to add their own attributes to a crate without changing the source code.

The exact reason I need this is to implement "edition runs" in Crater: we need to add the preview feature flag to every crate, and editing the crates' source code on the fly might produce unexpected results, while a compiler flag is more reliable.

cc rust-lang/crater#282 @Mark-Simulacrum

ojeda mentioned this pull request