fix: ignore renames for crate root

crates/ide-db/src/rename.rs

@@ -177,6 +177,10 @@ fn rename_mod(
 
     let mut source_change = SourceChange::default();
 
+    if module.is_crate_root(sema.db) {
+        return Ok(source_change);
+    }
+
     let InFile { file_id, value: def_source } = module.definition_source(sema.db);
     if let ModuleSource::SourceFile(..) = def_source {
         let anchor = file_id.original_file(sema.db);

crates/ide/src/rename.rs

@@ -379,6 +379,15 @@ fn check_expect(new_name: &str, ra_fixture: &str, expect: Expect) {
         expect.assert_debug_eq(&source_change)
     }
 
+    fn check_expect_will_rename_file(new_name: &str, ra_fixture: &str, expect: Expect) {
+        let (analysis, position) = fixture::position(ra_fixture);
+        let source_change = analysis
+            .will_rename_file(position.file_id, new_name)
+            .unwrap()
+            .expect("Expect returned a RenameError");
+        expect.assert_debug_eq(&source_change)
+    }
+
     fn check_prepare(ra_fixture: &str, expect: Expect) {
         let (analysis, position) = fixture::position(ra_fixture);
         let result = analysis
@@ -1245,6 +1254,26 @@ macro_rules! submodule {
         )
     }
 
+    #[test]
+    fn test_rename_mod_for_crate_root() {
+        check_expect_will_rename_file(
+            "main",
+            r#"
+//- /lib.rs
+use crate::foo as bar;
+fn foo() {}
+mod bar$0;
+"#,
+            expect![[r#"
+                SourceChange {
+                    source_file_edits: {},
+                    file_system_edits: [],
+                    is_snippet: false,
+                }
+                "#]],
+        )
+    }
+
     #[test]
     fn test_enum_variant_from_module_1() {
         cov_mark::check!(rename_non_local);