Auto merge of #106053 - compiler-errors:incr-test-revision, r=Mark-Si…

…mulacrum

Take revision into account in non-incremental-mode `// incremental` tests

A UI test I added in #105983 confusingly [failed](#106031 (comment)) in a merge because two different revisions raced with each other for the same incremental directory for a (non-incremental-mode, i.e. `src/test/ui`) UI test.

Let's take the revision name into account when generating an incremental directory so that other UI tests that combine `// incremental` and `// revisions` won't race and cause possible flakiness in CI.

src/tools/compiletest/src/common.rs

@@ -617,6 +617,6 @@ pub fn output_base_name(config: &Config, testpaths: &TestPaths, revision: Option
 
 /// Absolute path to the directory to use for incremental compilation. Example:
 ///   /path/to/build/host-triple/test/ui/relative/testname.mode/testname.inc
-pub fn incremental_dir(config: &Config, testpaths: &TestPaths) -> PathBuf {
-    output_base_name(config, testpaths, None).with_extension("inc")
+pub fn incremental_dir(config: &Config, testpaths: &TestPaths, revision: Option<&str>) -> PathBuf {
+    output_base_name(config, testpaths, revision).with_extension("inc")
 }

src/tools/compiletest/src/runtest.rs

@@ -117,8 +117,12 @@ pub fn run(config: Config, testpaths: &TestPaths, revision: Option<&str>) {
     }
     debug!("running {:?}", testpaths.file.display());
     let mut props = TestProps::from_file(&testpaths.file, revision, &config);
+
+    // For non-incremental (i.e. regular UI) tests, the incremental directory
+    // takes into account the revision name, since the revisions are independent
+    // of each other and can race.
     if props.incremental {
-        props.incremental_dir = Some(incremental_dir(&config, testpaths));
+        props.incremental_dir = Some(incremental_dir(&config, testpaths, revision));
     }
 
     let cx = TestCx { config: &config, props: &props, testpaths, revision };