check rust lints when an unknown lint is detected

compiler/rustc_lint/messages.ftl

@@ -532,8 +532,14 @@ lint_unknown_gated_lint =
 
 lint_unknown_lint =
     unknown lint: `{$name}`
-    .suggestion = did you mean
-    .help = did you mean: `{$replace}`
+    .suggestion = {$from_rustc ->
+        [true] a lint with the similar name exists in `rustc` lints
+        *[false] did you mean
+    }
+    .help = {$from_rustc ->
+        [true] a lint with the similar name exists in `rustc`, did you mean: `{$replace}`
+        *[false] did you mean: `{$replace}`
+    }
 
 lint_unknown_tool_in_scoped_lint = unknown tool name `{$tool_name}` found in scoped lint: `{$tool_name}::{$lint_name}`
     .help = add `#![register_tool({$tool_name})]` to the crate root

compiler/rustc_lint/src/context.rs

@@ -117,7 +117,7 @@ struct LintGroup {
 pub enum CheckLintNameResult<'a> {
     Ok(&'a [LintId]),
     /// Lint doesn't exist. Potentially contains a suggestion for a correct lint name.
-    NoLint(Option<Symbol>),
+    NoLint(Option<(Symbol, bool)>),
     /// The lint refers to a tool that has not been registered.
     NoTool,
     /// The lint has been renamed to a new name.
@@ -377,7 +377,7 @@ impl LintStore {
                         debug!("lints={:?}", self.by_name.keys().collect::<Vec<_>>());
                         let tool_prefix = format!("{tool_name}::");
                         return if self.by_name.keys().any(|lint| lint.starts_with(&tool_prefix)) {
-                            self.no_lint_suggestion(&complete_name)
+                            self.no_lint_suggestion(&complete_name, tool_name.as_str())
                         } else {
                             // 2. The tool isn't currently running, so no lints will be registered.
                             // To avoid giving a false positive, ignore all unknown lints.
@@ -419,13 +419,14 @@ impl LintStore {
         }
     }
 
-    fn no_lint_suggestion(&self, lint_name: &str) -> CheckLintNameResult<'_> {
+    fn no_lint_suggestion(&self, lint_name: &str, tool_name: &str) -> CheckLintNameResult<'_> {
         let name_lower = lint_name.to_lowercase();
 
         if lint_name.chars().any(char::is_uppercase) && self.find_lints(&name_lower).is_ok() {
             // First check if the lint name is (partly) in upper case instead of lower case...
-            return CheckLintNameResult::NoLint(Some(Symbol::intern(&name_lower)));
+            return CheckLintNameResult::NoLint(Some((Symbol::intern(&name_lower), false)));
         }
+
         // ...if not, search for lints with a similar name
         // Note: find_best_match_for_name depends on the sort order of its input vector.
         // To ensure deterministic output, sort elements of the lint_groups hash map.
@@ -440,8 +441,28 @@ impl LintStore {
         groups.sort();
         let groups = groups.iter().map(|k| Symbol::intern(k));
         let lints = self.lints.iter().map(|l| Symbol::intern(&l.name_lower()));
-        let names: Vec<Symbol> = groups.chain(lints).collect();
-        let suggestion = find_best_match_for_name(&names, Symbol::intern(&name_lower), None);
+        let mut names: Vec<Symbol> = groups.chain(lints).collect();
+        // Here, a little bit of extra hack is needed to get the right suggestion,
+        // we use the lint names from rustc and to mock the tool name,
+        // if it's selected we strip to the right suggestion
+        // so we can handle these cases:
+        //  1. suggest `missing_docs` from rustc for `clippy::missing_docs`
+        //  2. suggest `dead_code` from rustc for `clippy::dead_cod`
+        let rustc_names = self
+            .by_name
+            .keys()
+            .map(|k| Symbol::intern(&format!("{tool_name}::{k}")))
+            .collect::<Vec<_>>();
+        names.extend(rustc_names.clone());
+        let suggestion =
+            find_best_match_for_name(&names, Symbol::intern(&name_lower), None).map(|s| {
+                if rustc_names.contains(&s) {
+                    let stripped = s.as_str().strip_prefix(&format!("{tool_name}::")).unwrap();
+                    (Symbol::intern(stripped), true)
+                } else {
+                    (s, false)
+                }
+            });
         CheckLintNameResult::NoLint(suggestion)
     }
 
@@ -454,7 +475,7 @@ impl LintStore {
         match self.by_name.get(&complete_name) {
             None => match self.lint_groups.get(&*complete_name) {
                 // Now we are sure, that this lint exists nowhere
-                None => self.no_lint_suggestion(lint_name),
+                None => self.no_lint_suggestion(lint_name, tool_name),
                 Some(LintGroup { lint_ids, depr, .. }) => {
                     // Reaching this would be weird, but let's cover this case anyway
                     if let Some(LintAlias { name, silent }) = depr {

compiler/rustc_lint/src/levels.rs

@@ -570,7 +570,7 @@ impl<'s, P: LintLevelsProvider> LintLevelsBuilder<'s, P> {
                 CheckLintNameResult::Renamed(ref replace) => {
                     let name = lint_name.as_str();
                     let suggestion = RenamedLintSuggestion::WithoutSpan { replace };
-                    let requested_level = RequestedLevel { level, lint_name };
+                    let requested_level: RequestedLevel<'_> = RequestedLevel { level, lint_name };
                     let lint = RenamedLintFromCommandLine { name, suggestion, requested_level };
                     self.emit_lint(RENAMED_AND_REMOVED_LINTS, lint);
                 }
@@ -582,8 +582,9 @@ impl<'s, P: LintLevelsProvider> LintLevelsBuilder<'s, P> {
                 }
                 CheckLintNameResult::NoLint(suggestion) => {
                     let name = lint_name.clone();
-                    let suggestion =
-                        suggestion.map(|replace| UnknownLintSuggestion::WithoutSpan { replace });
+                    let suggestion = suggestion.map(|(replace, from_rustc)| {
+                        UnknownLintSuggestion::WithoutSpan { replace, from_rustc }
+                    });
                     let requested_level = RequestedLevel { level, lint_name };
                     let lint = UnknownLintFromCommandLine { name, suggestion, requested_level };
                     self.emit_lint(UNKNOWN_LINTS, lint);
@@ -990,8 +991,8 @@ impl<'s, P: LintLevelsProvider> LintLevelsBuilder<'s, P> {
                         } else {
                             name.to_string()
                         };
-                        let suggestion = suggestion.map(|replace| {
-                            UnknownLintSuggestion::WithSpan { suggestion: sp, replace }
+                        let suggestion = suggestion.map(|(replace, from_rustc)| {
+                            UnknownLintSuggestion::WithSpan { suggestion: sp, replace, from_rustc }
                         });
                         let lint = UnknownLint { name, suggestion };
                         self.emit_spanned_lint(UNKNOWN_LINTS, sp.into(), lint);

compiler/rustc_lint/src/lints.rs

@@ -1050,9 +1050,10 @@ pub enum UnknownLintSuggestion {
         #[primary_span]
         suggestion: Span,
         replace: Symbol,
+        from_rustc: bool,
     },
     #[help(lint_help)]
-    WithoutSpan { replace: Symbol },
+    WithoutSpan { replace: Symbol, from_rustc: bool },
 }
 
 #[derive(LintDiagnostic)]

src/tools/clippy/tests/ui/unknown_clippy_lints.fixed

@@ -8,9 +8,11 @@
 #[warn(clippy::unnecessary_cast)]
 #[warn(clippy::useless_transmute)]
 // Shouldn't suggest rustc lint name(`dead_code`)
-#[warn(clippy::eq_op)]
+#[warn(dead_code)]
 // Shouldn't suggest removed/deprecated clippy lint name(`unused_collect`)
 #[warn(clippy::unused_self)]
 // Shouldn't suggest renamed clippy lint name(`const_static_lifetime`)
 #[warn(clippy::redundant_static_lifetimes)]
+// issue #118183, should report `missing_docs` from rustc lint
+#[warn(missing_docs)]
 fn main() {}

src/tools/clippy/tests/ui/unknown_clippy_lints.rs

@@ -13,4 +13,6 @@
 #[warn(clippy::unused_colle)]
 // Shouldn't suggest renamed clippy lint name(`const_static_lifetime`)
 #[warn(clippy::const_static_lifetim)]
+// issue #118183, should report `missing_docs` from rustc lint
+#[warn(clippy::missing_docs)]
 fn main() {}

src/tools/clippy/tests/ui/unknown_clippy_lints.stderr

@@ -35,7 +35,12 @@ error: unknown lint: `clippy::dead_cod`
   --> $DIR/unknown_clippy_lints.rs:11:8
    |
 LL | #[warn(clippy::dead_cod)]
-   |        ^^^^^^^^^^^^^^^^ help: did you mean: `clippy::eq_op`
+   |        ^^^^^^^^^^^^^^^^
+   |
+help: a lint with the similar name exists in `rustc` lints
+   |
+LL | #[warn(dead_code)]
+   |        ~~~~~~~~~
 
 error: unknown lint: `clippy::unused_colle`
   --> $DIR/unknown_clippy_lints.rs:13:8
@@ -49,5 +54,16 @@ error: unknown lint: `clippy::const_static_lifetim`
 LL | #[warn(clippy::const_static_lifetim)]
    |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: did you mean: `clippy::redundant_static_lifetimes`
 
-error: aborting due to 8 previous errors
+error: unknown lint: `clippy::missing_docs`
+  --> $DIR/unknown_clippy_lints.rs:17:8
+   |
+LL | #[warn(clippy::missing_docs)]
+   |        ^^^^^^^^^^^^^^^^^^^^
+   |
+help: a lint with the similar name exists in `rustc` lints
+   |
+LL | #[warn(missing_docs)]
+   |        ~~~~~~~~~~~~
+
+error: aborting due to 9 previous errors
 

tests/rustdoc-ui/lints/unknown-renamed-lints.stderr

@@ -57,6 +57,11 @@ error: unknown lint: `rustdoc::intra_doc_link_resolution_failure`
    |
 LL | #![deny(rustdoc::intra_doc_link_resolution_failure)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: a lint with the similar name exists in `rustc` lints
+   |
+LL | #![deny(intra_doc_link_resolution_failure)]
+   |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 error: aborting due to 8 previous errors
 

tests/ui/lint/issue-83477.rs

@@ -4,7 +4,7 @@
 
 #[allow(rustc::foo::bar::default_hash_types)]
 //~^ WARN unknown lint: `rustc::foo::bar::default_hash_types`
-//~| HELP did you mean
+//~| HELP a lint with the similar name exists in `rustc` lints
 //~| SUGGESTION rustc::default_hash_types
 #[allow(rustc::foo::default_hash_types)]
 //~^ WARN unknown lint: `rustc::foo::default_hash_types`

tests/ui/lint/issue-83477.stderr

@@ -2,9 +2,13 @@ warning: unknown lint: `rustc::foo::bar::default_hash_types`
   --> $DIR/issue-83477.rs:5:9
    |
 LL | #[allow(rustc::foo::bar::default_hash_types)]
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: did you mean: `rustc::default_hash_types`
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: `#[warn(unknown_lints)]` on by default
+help: a lint with the similar name exists in `rustc` lints
+   |
+LL | #[allow(rustc::default_hash_types)]
+   |         ~~~~~~~~~~~~~~~~~~~~~~~~~
 
 warning: unknown lint: `rustc::foo::default_hash_types`
   --> $DIR/issue-83477.rs:9:9