pacify Unrecognized tidy directive lint

Author: klensy

src/tools/tidy/src/style.rs

@@ -507,8 +507,10 @@ pub fn check(path: &Path, bad: &mut bool) {
                         .any(|directive| matches!(directive, Directive::Ignore(_)));
                 let has_alphabetical_directive = line.contains("tidy-alphabetical-start")
                     || line.contains("tidy-alphabetical-end");
-                let has_recognized_directive =
-                    has_recognized_ignore_directive || has_alphabetical_directive;
+                let has_tidy_watcher_directive = line.contains("tidy-keep-sync-with");
+                let has_recognized_directive = has_recognized_ignore_directive
+                    || has_alphabetical_directive
+                    || has_tidy_watcher_directive;
                 if contains_potential_directive && (!has_recognized_directive) {
                     err("Unrecognized tidy directive")
                 }

src/tools/tidy/src/watcher/tests.rs

@@ -35,10 +35,10 @@ fn test_span_hash_has_some_text_in_line_before_second_tag() {
     let source = r#"
 RUN ./build-clang.sh
 ENV CC=clang CXX=clang++
-# tidy-ticket-perf-commit
+# tidy-keep-sync-with=tidy-ticket-perf-commit
 # rustc-perf version from 2023-05-30
 ENV PERF_COMMIT 8b2ac3042e1ff2c0074455a0a3618adef97156b1
-# tidy-ticket-perf-commit
+# tidy-keep-sync-with=tidy-ticket-perf-commit
 RUN curl -LS -o perf.zip https://github.com/rust-lang/rustc-perf/archive/$PERF_COMMIT.zip && \
     unzip perf.zip && \
     mv rustc-perf-$PERF_COMMIT rustc-perf && \