Update docs and diagnostics

Author: oli-obk

src/test/COMPILER_TESTS.md

@@ -140,13 +140,9 @@ check that the test compiles successfully.
 ### Editing and updating the reference files
 
 If you have changed the compiler's output intentionally, or you are
-making a new test, you can use the script `ui/update-references.sh` to
-update the references. When you run the test framework, it will report
-various errors: in those errors is a command you can use to run the
-`ui/update-references.sh` script, which will then copy over the files
-from the build directory and use them as the new reference. You can
-also just run `ui/update-all-references.sh`. In both cases, you can run
-the script with `--help` to get a help message.
+making a new test, you can pass `--bless` to the command you used to
+run the tests. This will then copy over the files
+from the build directory and use them as the new reference.
 
 ### Normalization
 

src/tools/compiletest/src/runtest.rs

@@ -2596,15 +2596,13 @@ impl<'test> TestCx<'test> {
         }
 
         if errors > 0 {
-            println!("To update references, run this command from build directory:");
+            println!("To update references, rerun the tests and pass the `--bless` flag");
             let relative_path_to_file = self.testpaths
                 .relative_dir
                 .join(self.testpaths.file.file_name().unwrap());
             println!(
-                "{}/update-references.sh '{}' '{}'",
-                self.config.src_base.display(),
-                self.config.build_base.display(),
-                relative_path_to_file.display()
+                "To only update this specific test, also pass `--test-args {}`",
+                relative_path_to_file.display(),
             );
             self.fatal_proc_rec(
                 &format!("{} errors occurred comparing output.", errors),