mirror of
https://github.com/rust-lang/rust.git
synced 2024-11-27 01:04:03 +00:00
8b9ef3b996
coverage: Remove or migrate all unstable values of `-Cinstrument-coverage` (This PR was substantially overhauled from its original version, which migrated all of the existing unstable values intact.) This PR takes the three nightly-only values that are currently accepted by `-Cinstrument-coverage`, completely removes two of them (`except-unused-functions` and `except-unused-generics`), and migrates the third (`branch`) over to a newly-introduced unstable flag `-Zcoverage-options`. I have a few motivations for wanting to do this: - It's unclear whether anyone actually uses the `except-unused-*` values, so this serves as an opportunity to either remove them, or prompt existing users to object to their removal. - After #117199, the stable values of `-Cinstrument-coverage` treat it as a boolean-valued flag, so having nightly-only extra values feels out-of-place. - Nightly-only values also require extra ad-hoc code to make sure they aren't accidentally exposed to stable users. - The new system allows multiple different settings to be toggled independently, which isn't possible in the current single-value system. - The new system makes it easier to introduce new behaviour behind an unstable toggle, and then gather nightly-user feedback before possibly making it the default behaviour for all users. - The new system also gives us a convenient place to put relatively-narrow options that won't ever be the default, but that nightly users might still want access to. - It's likely that we will eventually want to give stable users more fine-grained control over coverage instrumentation. The new flag serves as a prototype of what that stable UI might eventually look like. The `branch` option is a placeholder that currently does nothing. It will be used by #122322 to opt into branch coverage instrumentation. --- I see `-Zcoverage-options` as something that will exist more-or-less indefinitely, though individual sub-options might come and go as appropriate. I think there will always be some demand for nightly-only toggles, so I don't see `-Zcoverage-options` itself ever being stable, though we might eventually stabilize something similar to it. |
||
|---|---|---|
| .. | ||
| src | ||
| Cargo.toml | ||
| messages.ftl | ||
| README.md | ||
The codegen crate contains the code to convert from MIR into LLVM IR,
and then from LLVM IR into machine code. In general it contains code
that runs towards the end of the compilation process.
For more information about how codegen works, see the rustc dev guide.