add comments and LintGroup struct for more clarity

Author: karolzwolak

compiler/rustc_lint/src/context.rs

@@ -63,8 +63,10 @@ pub struct LintStore {
 }
 
 impl LintStoreMarker for LintStore {
-    fn lint_groups(&self) -> Box<dyn Iterator<Item = (&'static str, Vec<LintId>, bool)> + '_> {
-        Box::new(self.get_lint_groups())
+    fn lint_groups_iter(&self) -> Box<dyn Iterator<Item = rustc_session::LintGroup> + '_> {
+        Box::new(self.get_lint_groups().map(|(name, lints, is_externally_loaded)| {
+            rustc_session::LintGroup { name, lints, is_externally_loaded }
+        }))
     }
 }
 

compiler/rustc_middle/src/lint.rs

@@ -217,22 +217,27 @@ fn explain_lint_level_source(
     src: LintLevelSource,
     err: &mut Diag<'_, ()>,
 ) {
+    /// Find the name of the lint group that contains the given lint.
+    /// Assumes the lint only belongs to one group.
     fn lint_group_name(
         lint: &'static Lint,
         sess: &Session,
         allow_external: bool,
     ) -> Option<&'static str> {
-        let mut lint_groups_iter = sess.lint_groups();
+        let mut lint_groups_iter = sess.lint_groups_iter();
         let lint_id = LintId::of(lint);
         lint_groups_iter
             .find(|lint_group| {
-                let lints = &lint_group.1;
-                if !allow_external && lint_group.2 {
+                if !allow_external && lint_group.is_externally_loaded {
                     return false;
                 }
-                lints.iter().find(|lint_group_lint| **lint_group_lint == lint_id).is_some()
+                lint_group
+                    .lints
+                    .iter()
+                    .find(|lint_group_lint| **lint_group_lint == lint_id)
+                    .is_some()
             })
-            .map(|lint_group| lint_group.0)
+            .map(|lint_group| lint_group.name)
     }
     let name = lint.name_lower();
     if let Level::Allow = level {

compiler/rustc_session/src/session.rs

@@ -141,7 +141,8 @@ pub struct CompilerIO {
 }
 
 pub trait LintStoreMarker: Any + DynSync + DynSend {
-    fn lint_groups(&self) -> Box<dyn Iterator<Item = (&'static str, Vec<LintId>, bool)> + '_>;
+    /// Provides a way to access lint groups without depending on `rustc_lint`
+    fn lint_groups_iter(&self) -> Box<dyn Iterator<Item = LintGroup> + '_>;
 }
 
 /// Represents the data associated with a compilation
@@ -243,6 +244,12 @@ impl CodegenUnits {
     }
 }
 
+pub struct LintGroup {
+    pub name: &'static str,
+    pub lints: Vec<LintId>,
+    pub is_externally_loaded: bool,
+}
+
 impl Session {
     pub fn miri_unleashed_feature(&self, span: Span, feature_gate: Option<Symbol>) {
         self.miri_unleashed_features.lock().push((span, feature_gate));
@@ -600,9 +607,9 @@ impl Session {
         }
     }
 
-    pub fn lint_groups(&self) -> Box<dyn Iterator<Item = (&'static str, Vec<LintId>, bool)> + '_> {
+    pub fn lint_groups_iter(&self) -> Box<dyn Iterator<Item = LintGroup> + '_> {
         match self.lint_store {
-            Some(ref lint_store) => lint_store.lint_groups(),
+            Some(ref lint_store) => lint_store.lint_groups_iter(),
             None => Box::new(std::iter::empty()),
         }
     }