compiletest: Remove/don't write empty 'expected' files

src/tools/compiletest/src/runtest.rs

@@ -213,7 +213,7 @@ fn remove_and_create_dir_all(path: &Path) {
     fs::create_dir_all(path).unwrap();
 }
 
-#[derive(Copy, Clone)]
+#[derive(Copy, Clone, Debug)]
 struct TestCx<'test> {
     config: &'test Config,
     props: &'test TestProps,
@@ -2589,7 +2589,14 @@ impl<'test> TestCx<'test> {
         actual: &str,
         actual_unnormalized: &str,
         expected: &str,
-    ) -> bool {
+    ) -> CompareOutcome {
+        let expected_path =
+            expected_output_path(self.testpaths, self.revision, &self.config.compare_mode, stream);
+
+        if self.config.bless && actual.is_empty() && expected_path.exists() {
+            self.delete_file(&expected_path);
+        }
+
         let are_different = match (self.force_color_svg(), expected.find('\n'), actual.find('\n')) {
             // FIXME: We ignore the first line of SVG files
             // because the width parameter is non-deterministic.
@@ -2639,9 +2646,6 @@ impl<'test> TestCx<'test> {
         }
         println!("Saved the actual {stream} to {actual_path:?}");
 
-        let expected_path =
-            expected_output_path(self.testpaths, self.revision, &self.config.compare_mode, stream);
-
         if !self.config.bless {
             if expected.is_empty() {
                 println!("normalized {}:\n{}\n", stream, actual);
@@ -2664,10 +2668,12 @@ impl<'test> TestCx<'test> {
                 self.delete_file(&old);
             }
 
-            if let Err(err) = fs::write(&expected_path, &actual) {
-                self.fatal(&format!("failed to write {stream} to `{expected_path:?}`: {err}"));
+            if !actual.is_empty() {
+                if let Err(err) = fs::write(&expected_path, &actual) {
+                    self.fatal(&format!("failed to write {stream} to `{expected_path:?}`: {err}"));
+                }
+                println!("Blessing the {stream} of {test_name} in {expected_path:?}");
             }
-            println!("Blessing the {stream} of {test_name} in {expected_path:?}");
         }
 
         println!("\nThe actual {0} differed from the expected {0}.", stream);