Cleanup: unify lint name checking

This change merges `check_lint_and_tool_name` into `check_lint_name` in
order to avoid having two very similar functions.

Also adds the `.stderr` file back for the test case, since apparently
it is still needed.

compiler/rustc_lint/src/context.rs

@@ -344,9 +344,9 @@ impl LintStore {
         level: Level,
         crate_attrs: &[ast::Attribute],
     ) {
-        let (tool_name, lint_name) = parse_lint_and_tool_name(lint_name);
+        let (tool_name, lint_name_only) = parse_lint_and_tool_name(lint_name);
 
-        let db = match self.check_lint_and_tool_name(sess, tool_name, lint_name, crate_attrs) {
+        let db = match self.check_lint_name(sess, lint_name_only, tool_name, crate_attrs) {
             CheckLintNameResult::Ok(_) => None,
             CheckLintNameResult::Warning(ref msg, _) => Some(sess.struct_warn(msg)),
             CheckLintNameResult::NoLint(suggestion) => {
@@ -408,22 +408,6 @@ impl LintStore {
         }
     }
 
-    pub fn check_lint_and_tool_name(
-        &self,
-        sess: &Session,
-        tool_name: Option<Symbol>,
-        lint_name: &str,
-        crate_attrs: &[ast::Attribute],
-    ) -> CheckLintNameResult<'_> {
-        if let Some(tool_name) = tool_name {
-            if !is_known_lint_tool(tool_name, sess, crate_attrs) {
-                return CheckLintNameResult::NoTool;
-            }
-        }
-
-        self.check_lint_name(lint_name, tool_name)
-    }
-
     /// Checks the name of a lint for its existence, and whether it was
     /// renamed or removed. Generates a DiagnosticBuilder containing a
     /// warning for renamed and removed lints. This is over both lint
@@ -433,9 +417,17 @@ impl LintStore {
     /// printing duplicate warnings.
     pub fn check_lint_name(
         &self,
+        sess: &Session,
         lint_name: &str,
         tool_name: Option<Symbol>,
+        crate_attrs: &[ast::Attribute],
     ) -> CheckLintNameResult<'_> {
+        if let Some(tool_name) = tool_name {
+            if !is_known_lint_tool(tool_name, sess, crate_attrs) {
+                return CheckLintNameResult::NoTool;
+            }
+        }
+
         let complete_name = if let Some(tool_name) = tool_name {
             format!("{}::{}", tool_name, lint_name)
         } else {

compiler/rustc_lint/src/levels.rs

@@ -328,8 +328,7 @@ impl<'s> LintLevelsBuilder<'s> {
                 };
                 let tool_name = tool_ident.map(|ident| ident.name);
                 let name = pprust::path_to_string(&meta_item.path);
-                let lint_result =
-                    store.check_lint_and_tool_name(sess, tool_name, &name, self.crate_attrs);
+                let lint_result = store.check_lint_name(sess, &name, tool_name, self.crate_attrs);
                 match &lint_result {
                     CheckLintNameResult::Ok(ids) => {
                         let src = LintLevelSource::Node(
@@ -477,7 +476,9 @@ impl<'s> LintLevelsBuilder<'s> {
                 if let CheckLintNameResult::Warning(_, Some(new_name)) = lint_result {
                     // Ignore any errors or warnings that happen because the new name is inaccurate
                     // NOTE: `new_name` already includes the tool name, so we don't have to add it again.
-                    if let CheckLintNameResult::Ok(ids) = store.check_lint_name(&new_name, None) {
+                    if let CheckLintNameResult::Ok(ids) =
+                        store.check_lint_name(sess, &new_name, None, self.crate_attrs)
+                    {
                         let src = LintLevelSource::Node(Symbol::intern(&new_name), sp, reason);
                         for &id in ids {
                             self.check_gated_lint(id, attr.span);

src/test/ui/lint/command-line-register-unknown-lint-tool.stderr

@@ -0,0 +1,11 @@
+error[E0602]: unknown lint tool: `unknown_tool`
+   |
+   = note: requested on the command line with `-A unknown_tool::foo`
+
+error[E0602]: unknown lint tool: `unknown_tool`
+   |
+   = note: requested on the command line with `-A unknown_tool::foo`
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0602`.