Make fail-fast unstable

Author: sourcefrog

library/test/src/cli.rs

@@ -262,6 +262,7 @@ fn parse_opts_impl(matches: getopts::Matches) -> OptRes {
     // Unstable flags
     let force_run_in_process = unstable_optflag!(matches, allow_unstable, "force-run-in-process");
     let exclude_should_panic = unstable_optflag!(matches, allow_unstable, "exclude-should-panic");
+    let fail_fast = unstable_optflag!(matches, allow_unstable, "fail-fast");
     let time_options = get_time_options(&matches, allow_unstable)?;
     let shuffle = get_shuffle(&matches, allow_unstable)?;
     let shuffle_seed = get_shuffle_seed(&matches, allow_unstable)?;
@@ -271,7 +272,6 @@ fn parse_opts_impl(matches: getopts::Matches) -> OptRes {
     let exact = matches.opt_present("exact");
     let list = matches.opt_present("list");
     let skip = matches.opt_strs("skip");
-    let fail_fast = matches.opt_present("fail-fast");
 
     let bench_benchmarks = matches.opt_present("bench");
     let run_tests = !bench_benchmarks || matches.opt_present("test");

src/doc/rustc/src/tests/index.md

@@ -168,6 +168,8 @@ other threads will be allowed to run to completion before the process exits.
 Note that when running tests in parallel, the test execution order is non-deterministic:
 if multiple tests would fail, the first failure encountered will be reported.
 
+⚠️ 🚧 This requires the `-Z unstable-options` flag.
+
 #### `--test-threads` _NUM_THREADS_
 
 Sets the number of threads to use for running tests in parallel. By default,