Fix docs, fix incorrect lint source in note

compiler/rustc_lint/src/levels.rs

@@ -601,10 +601,11 @@ impl<'s> LintLevelsBuilder<'s> {
     fn check_gated_lint(&self, lint_id: LintId, span: Span) -> bool {
         if let Some(feature) = lint_id.lint.feature_gate {
             if !self.sess.features_untracked().enabled(feature) {
+                let lint = builtin::UNKNOWN_LINTS;
                 let (level, src) = self.lint_level(builtin::UNKNOWN_LINTS);
-                struct_lint_level(self.sess, lint_id.lint, level, src, Some(span.into()), |lint| {
+                struct_lint_level(self.sess, lint, level, src, Some(span.into()), |lint_db| {
                     let mut db =
-                        lint.build(&format!("unknown lint: `{}`", lint_id.lint.name_lower()));
+                        lint_db.build(&format!("unknown lint: `{}`", lint_id.lint.name_lower()));
                     db.note(&format!("the `{}` lint is unstable", lint_id.lint.name_lower(),));
                     add_feature_diagnostics(&mut db, &self.sess.parse_sess, feature);
                     db.emit();

compiler/rustc_lint_defs/src/builtin.rs

@@ -3786,7 +3786,7 @@ declare_lint! {
     ///
     /// ### Explanation
     ///
-    /// In order to test the behavior of unstable traits, a permanently-unstable
+    /// In order to test the behavior of unstable lints, a permanently-unstable
     /// lint is required. This lint can be used to trigger warnings and errors
     /// from the compiler related to unstable lints.
     pub TEST_UNSTABLE_LINT,

src/test/ui/feature-gates/feature-gate-non_exhaustive_omitted_patterns_lint.stderr

@@ -4,7 +4,7 @@ warning: unknown lint: `non_exhaustive_omitted_patterns`
 LL | #![deny(non_exhaustive_omitted_patterns)]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-   = note: `#[warn(non_exhaustive_omitted_patterns)]` on by default
+   = note: `#[warn(unknown_lints)]` on by default
    = note: the `non_exhaustive_omitted_patterns` lint is unstable
    = note: see issue #89554 <https://github.com/rust-lang/rust/issues/89554> for more information
    = help: add `#![feature(non_exhaustive_omitted_patterns_lint)]` to the crate attributes to enable

src/test/ui/feature-gates/feature-gate-test_unstable_lint.stderr

@@ -4,7 +4,7 @@ warning: unknown lint: `test_unstable_lint`
 LL | #![allow(test_unstable_lint)]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-   = note: `#[warn(test_unstable_lint)]` on by default
+   = note: `#[warn(unknown_lints)]` on by default
    = note: the `test_unstable_lint` lint is unstable
    = help: add `#![feature(test_unstable_lint)]` to the crate attributes to enable
 

src/test/ui/lint/must_not_suspend/gated.stderr

@@ -4,7 +4,7 @@ warning: unknown lint: `must_not_suspend`
 LL | #![deny(must_not_suspend)]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-   = note: `#[warn(must_not_suspend)]` on by default
+   = note: `#[warn(unknown_lints)]` on by default
    = note: the `must_not_suspend` lint is unstable
    = note: see issue #83310 <https://github.com/rust-lang/rust/issues/83310> for more information
    = help: add `#![feature(must_not_suspend)]` to the crate attributes to enable

src/test/ui/unknown-unstable-lints/deny-unstable-lint-command-line.stderr

@@ -1,6 +1,6 @@
 error: unknown lint: `test_unstable_lint`
    |
-   = note: `-D test-unstable-lint` implied by `-D unknown-lints`
+   = note: requested on the command line with `-D unknown-lints`
    = note: the `test_unstable_lint` lint is unstable
    = help: add `#![feature(test_unstable_lint)]` to the crate attributes to enable
 

src/test/ui/unknown-unstable-lints/deny-unstable-lint-inline.stderr

@@ -9,7 +9,6 @@ note: the lint level is defined here
    |
 LL | #![deny(unknown_lints)]
    |         ^^^^^^^^^^^^^
-   = note: `#[deny(test_unstable_lint)]` implied by `#[deny(unknown_lints)]`
    = note: the `test_unstable_lint` lint is unstable
    = help: add `#![feature(test_unstable_lint)]` to the crate attributes to enable
 

src/test/ui/unknown-unstable-lints/warn-unknown-unstable-lint-command-line.stderr

@@ -1,6 +1,6 @@
 warning: unknown lint: `test_unstable_lint`
    |
-   = note: `-W test-unstable-lint` implied by `-W unknown-lints`
+   = note: requested on the command line with `-W unknown-lints`
    = note: the `test_unstable_lint` lint is unstable
    = help: add `#![feature(test_unstable_lint)]` to the crate attributes to enable
 

src/test/ui/unknown-unstable-lints/warn-unknown-unstable-lint-inline.stderr

@@ -9,7 +9,6 @@ note: the lint level is defined here
    |
 LL | #![warn(unknown_lints)]
    |         ^^^^^^^^^^^^^
-   = note: `#[warn(test_unstable_lint)]` implied by `#[warn(unknown_lints)]`
    = note: the `test_unstable_lint` lint is unstable
    = help: add `#![feature(test_unstable_lint)]` to the crate attributes to enable