Rename rustc_middle::lint::LintSource
Rename [`rustc_middle::lint::LintSource`](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/lint/enum.LintSource.html) to `rustc_middle::lint::LintLevelSource`.
This enum represents the source of a *lint level*, not a lint. This should improve code readability.
Update: Also documents `rustc_middle::lint::LevelSource` to clarify.
Properly handle lint spans after MIR inlining
The first commit shows what happens when we apply mir inlining and then cause lints on the inlined MIR.
The second commit fixes that.
r? `@wesleywiser`
Fixes#78660
With PR https://github.com/rust-lang/rust/pull/75534 merged, we now run
more lint-related code for future-incompat-report, even when their final
level is Allow. Some lint-related code was not expecting `Level::Allow`,
and had an explicit panic.
This PR explicitly tracks the lint level set on the command line before
`--cap-lints` is applied. This is used to emit a more precise error
note (e.g. we don't say that `-W lint-name` was specified on the
command line just because a lint was capped to Warn). As a result, we
can now correctly emit a note that `-A` was used if we got
`Level::Allow` from the command line (before the cap is applied).
