refactor: use references to reduce unnecessary clones

compiler/rustc_lint/src/context.rs

@@ -343,33 +343,32 @@ pub fn check_lint_name_cmdline(
             sess.emit_err(UnsupportedGroup { lint_group: crate::WARNINGS.name_lower() });
             return;
         }
-        let lint_name = lint_name.to_string();
         match self.check_lint_name(lint_name_only, tool_name, registered_tools) {
             CheckLintNameResult::Renamed(replace) => {
                 sess.emit_warning(CheckNameRenamed {
-                    lint_name: lint_name.clone(),
-                    replace,
+                    lint_name,
+                    replace: &replace,
                     sub: RequestedLevel { level, lint_name },
                 });
             }
             CheckLintNameResult::Removed(reason) => {
                 sess.emit_warning(CheckNameRemoved {
-                    lint_name: lint_name.clone(),
-                    reason,
+                    lint_name,
+                    reason: &reason,
                     sub: RequestedLevel { level, lint_name },
                 });
             }
             CheckLintNameResult::NoLint(suggestion) => {
                 sess.emit_err(CheckNameUnknown {
-                    lint_name: lint_name.clone(),
+                    lint_name,
                     suggestion,
                     sub: RequestedLevel { level, lint_name },
                 });
             }
             CheckLintNameResult::Tool(Err((Some(_), new_name))) => {
                 sess.emit_warning(CheckNameDeprecated {
-                    lint_name: lint_name.clone(),
-                    new_name,
+                    lint_name,
+                    new_name: &new_name,
                     sub: RequestedLevel { level, lint_name },
                 });
             }

compiler/rustc_lint/src/errors.rs

@@ -91,9 +91,9 @@ pub struct BuiltinEllipsisInclusiveRangePatterns {
 
 #[derive(Subdiagnostic)]
 #[note(lint_requested_level)]
-pub struct RequestedLevel {
+pub struct RequestedLevel<'a> {
     pub level: Level,
-    pub lint_name: String,
+    pub lint_name: &'a str,
 }
 
 #[derive(Diagnostic)]
@@ -102,13 +102,13 @@ pub struct UnsupportedGroup {
     pub lint_group: String,
 }
 
-pub struct CheckNameUnknown {
-    pub lint_name: String,
+pub struct CheckNameUnknown<'a> {
+    pub lint_name: &'a str,
     pub suggestion: Option<Symbol>,
-    pub sub: RequestedLevel,
+    pub sub: RequestedLevel<'a>,
 }
 
-impl IntoDiagnostic<'_> for CheckNameUnknown {
+impl IntoDiagnostic<'_> for CheckNameUnknown<'_> {
     fn into_diagnostic(
         self,
         handler: &Handler,
@@ -127,35 +127,35 @@ fn into_diagnostic(
 
 #[derive(Diagnostic)]
 #[diag(lint_check_name_unknown_tool, code = "E0602")]
-pub struct CheckNameUnknownTool {
+pub struct CheckNameUnknownTool<'a> {
     pub tool_name: Symbol,
     #[subdiagnostic]
-    pub sub: RequestedLevel,
+    pub sub: RequestedLevel<'a>,
 }
 
 #[derive(Diagnostic)]
 #[diag(lint_check_name_renamed)]
-pub struct CheckNameRenamed {
-    pub lint_name: String,
-    pub replace: String,
+pub struct CheckNameRenamed<'a> {
+    pub lint_name: &'a str,
+    pub replace: &'a str,
     #[subdiagnostic]
-    pub sub: RequestedLevel,
+    pub sub: RequestedLevel<'a>,
 }
 
 #[derive(Diagnostic)]
 #[diag(lint_check_name_removed)]
-pub struct CheckNameRemoved {
-    pub lint_name: String,
-    pub reason: String,
+pub struct CheckNameRemoved<'a> {
+    pub lint_name: &'a str,
+    pub reason: &'a str,
     #[subdiagnostic]
-    pub sub: RequestedLevel,
+    pub sub: RequestedLevel<'a>,
 }
 
 #[derive(Diagnostic)]
 #[diag(lint_check_name_deprecated)]
-pub struct CheckNameDeprecated {
-    pub lint_name: String,
-    pub new_name: String,
+pub struct CheckNameDeprecated<'a> {
+    pub lint_name: &'a str,
+    pub new_name: &'a str,
     #[subdiagnostic]
-    pub sub: RequestedLevel,
+    pub sub: RequestedLevel<'a>,
 }