Print a summary of which test suite failed

Especially on CI, where cross-compiling is common and single builder may end up
with multiple hosts and multiple targets, it can be annoying to scroll back to
the nearest start of test marker. This prints out a summary of the test suite
being run directly in compiletest.

src/bootstrap/test.rs

@@ -1039,6 +1039,7 @@ note: if you're sure you want to do this, please open an issue as to why. In the
         cmd.arg("--src-base").arg(builder.src.join("src/test").join(suite));
         cmd.arg("--build-base").arg(testdir(builder, compiler.host).join(suite));
         cmd.arg("--stage-id").arg(format!("stage{}-{}", compiler.stage, target));
+        cmd.arg("--suite").arg(suite);
         cmd.arg("--mode").arg(mode);
         cmd.arg("--target").arg(target.rustc_target_arg());
         cmd.arg("--host").arg(&*compiler.host.triple);

src/tools/compiletest/src/common.rs

@@ -224,6 +224,10 @@ pub struct Config {
     /// The test mode, compile-fail, run-fail, ui
     pub mode: Mode,
 
+    /// The test suite (essentially which directory is running, but without the
+    /// directory prefix such as src/test)
+    pub suite: String,
+
     /// The debugger to use in debuginfo mode. Unset otherwise.
     pub debugger: Option<Debugger>,
 

src/tools/compiletest/src/header/tests.rs

@@ -39,6 +39,7 @@ fn config() -> Config {
     let args = &[
         "compiletest",
         "--mode=ui",
+        "--suite=ui",
         "--compile-lib-path=",
         "--run-lib-path=",
         "--rustc-path=",

src/tools/compiletest/src/main.rs

@@ -70,6 +70,12 @@ pub fn parse_config(args: Vec<String>) -> Config {
             "compile-fail | run-fail | run-pass-valgrind | pretty | debug-info | codegen | rustdoc \
              codegen-units | incremental | run-make | ui | js-doc-test | mir-opt | assembly",
         )
+        .reqopt(
+            "",
+            "suite",
+            "which suite of compile tests to run. used for nicer error reporting.",
+            "SUITE",
+        )
         .optopt(
             "",
             "pass",
@@ -201,6 +207,7 @@ pub fn parse_config(args: Vec<String>) -> Config {
         build_base: opt_path(matches, "build-base"),
         stage_id: matches.opt_str("stage-id").unwrap(),
         mode: matches.opt_str("mode").unwrap().parse().expect("invalid mode"),
+        suite: matches.opt_str("suite").unwrap(),
         debugger: None,
         run_ignored,
         filter: matches.free.first().cloned(),
@@ -340,7 +347,7 @@ pub fn run_tests(config: Config) {
             configs.extend(configure_lldb(&config));
         }
     } else {
-        configs.push(config);
+        configs.push(config.clone());
     };
 
     let mut tests = Vec::new();
@@ -351,11 +358,32 @@ pub fn run_tests(config: Config) {
     let res = test::run_tests_console(&opts, tests);
     match res {
         Ok(true) => {}
-        Ok(false) => panic!("Some tests failed"),
+        Ok(false) => {
+            // We want to report that the tests failed, but we also want to give
+            // some indication of just what tests we were running. Especially on
+            // CI, where there can be cross-compiled tests for a lot of
+            // architectures, without this critical information it can be quite
+            // easy to miss which tests failed, and as such fail to reproduce
+            // the failure locally.
+
+            eprintln!(
+                "Some tests failed in compiletest suite={}{} mode={} host={} target={}",
+                config.suite,
+                config.compare_mode.map(|c| format!(" compare_mode={:?}", c)).unwrap_or_default(),
+                config.mode,
+                config.host,
+                config.target
+            );
+
+            std::process::exit(1);
+        }
         Err(e) => {
             // We don't know if tests passed or not, but if there was an error
             // during testing we don't want to just suceeed (we may not have
             // tested something), so fail.
+            //
+            // This should realistically "never" happen, so don't try to make
+            // this a pretty error message.
             panic!("I/O failure during tests: {:?}", e);
         }
     }