check rust lints when an unknown lint is detected

Author: chenyukang

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 = did you {$from_rustc ->
+        [true] `{$replace}`, a lint with the same name was found in `rustc` lints.
+        *[false] mean
+    }
+    .help = did you mean: {$from_rustc ->
+        [true] `{$replace}`, a lint with the same name was found in `rustc` lints.
+        *[false] `{$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.
@@ -424,8 +424,16 @@ impl LintStore {
 
         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)));
         }
+
+        // Try to suggest `missing_docs` from rustc for `clippy::missing_docs`
+        if let Some(name) = lint_name.split("::").last()
+            && let Some(_) = self.by_name.get(name)
+        {
+            return CheckLintNameResult::NoLint(Some((Symbol::intern(name), true)));
+        }
+
         // ...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.
@@ -441,7 +449,8 @@ impl LintStore {
         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 suggestion =
+            find_best_match_for_name(&names, Symbol::intern(&name_lower), None).map(|s| (s, false));
         CheckLintNameResult::NoLint(suggestion)
     }
 

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

@@ -13,4 +13,6 @@
 #[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

@@ -49,5 +49,16 @@ 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: did you `missing_docs`, a lint with the same name was found in `rustc` lints.
+   |
+LL | #[warn(missing_docs)]
+   |        ~~~~~~~~~~~~
+
+error: aborting due to 9 previous errors