Add must_use to `msg_` functions

This caught several places which weren't waiting until the command finished to drop the Group.

I also took the liberty of calling `msg_sysroot_tool` from `run_cargo_test` to reduce code duplication and make errors like this less likely in the future.

3 files changed, 67 insertions, 45 deletions

diff --git a/src/bootstrap/doc.rs b/src/bootstrap/doc.rs
index d20bfab4131..8ceaadbefac 100644
--- a/src/bootstrap/doc.rs
+++ b/src/bootstrap/doc.rs
@@ -221,7 +221,7 @@ impl Step for TheBook {
         let shared_assets = builder.ensure(SharedAssets { target });
 
         // build the redirect pages
-        builder.msg_doc(compiler, "book redirect pages", target);
+        let _guard = builder.msg_doc(compiler, "book redirect pages", target);
         for file in t!(fs::read_dir(builder.src.join(&relative_path).join("redirects"))) {
             let file = t!(file);
             let path = file.path();
@@ -305,7 +305,7 @@ impl Step for Standalone {
     fn run(self, builder: &Builder<'_>) {
         let target = self.target;
         let compiler = self.compiler;
-        builder.msg_doc(compiler, "standalone", target);
+        let _guard = builder.msg_doc(compiler, "standalone", target);
         let out = builder.doc_out(target);
         t!(fs::create_dir_all(&out));
 
@@ -799,8 +799,6 @@ macro_rules! tool_doc {
                     SourceType::Submodule
                 };
 
-                builder.msg_doc(compiler, stringify!($tool).to_lowercase(), target);
-
                 // Symlink compiler docs to the output directory of rustdoc documentation.
                 let out_dirs = [
                     builder.stage_out(compiler, Mode::ToolRustc).join(target.triple).join("doc"),
@@ -839,6 +837,8 @@ macro_rules! tool_doc {
                 cargo.rustdocflag("--show-type-layout");
                 cargo.rustdocflag("--generate-link-to-definition");
                 cargo.rustdocflag("-Zunstable-options");
+
+                let _guard = builder.msg_doc(compiler, stringify!($tool).to_lowercase(), target);
                 builder.run(&mut cargo.into());
             }
         }
diff --git a/src/bootstrap/lib.rs b/src/bootstrap/lib.rs
index f5ad4f336a7..7ffd1e1f9c5 100644
--- a/src/bootstrap/lib.rs
+++ b/src/bootstrap/lib.rs
@@ -999,6 +999,7 @@ impl Build {
         }
     }
 
+    #[must_use = "Groups should not be dropped until the Step finishes running"]
     fn msg_check(
         &self,
         what: impl Display,
@@ -1007,6 +1008,7 @@ impl Build {
         self.msg(Kind::Check, self.config.stage, what, self.config.build, target)
     }
 
+    #[must_use = "Groups should not be dropped until the Step finishes running"]
     fn msg_doc(
         &self,
         compiler: Compiler,
@@ -1016,6 +1018,7 @@ impl Build {
         self.msg(Kind::Doc, compiler.stage, what, compiler.host, target.into())
     }
 
+    #[must_use = "Groups should not be dropped until the Step finishes running"]
     fn msg_build(
         &self,
         compiler: Compiler,
@@ -1028,6 +1031,7 @@ impl Build {
     /// Return a `Group` guard for a [`Step`] that is built for each `--stage`.
     ///
     /// [`Step`]: crate::builder::Step
+    #[must_use = "Groups should not be dropped until the Step finishes running"]
     fn msg(
         &self,
         action: impl Into<Kind>,
@@ -1054,6 +1058,7 @@ impl Build {
     /// Return a `Group` guard for a [`Step`] that is only built once and isn't affected by `--stage`.
     ///
     /// [`Step`]: crate::builder::Step
+    #[must_use = "Groups should not be dropped until the Step finishes running"]
     fn msg_unstaged(
         &self,
         action: impl Into<Kind>,
@@ -1065,6 +1070,7 @@ impl Build {
         self.group(&msg)
     }
 
+    #[must_use = "Groups should not be dropped until the Step finishes running"]
     fn msg_sysroot_tool(
         &self,
         action: impl Into<Kind>,
diff --git a/src/bootstrap/test.rs b/src/bootstrap/test.rs
index da0c3767c5c..c8ec9f1a8ff 100644
--- a/src/bootstrap/test.rs
+++ b/src/bootstrap/test.rs
@@ -117,9 +117,8 @@ impl Step for CrateBootstrap {
             SourceType::InTree,
             &[],
         );
-        let _group = builder.msg(Kind::Test, compiler.stage, path, compiler.host, bootstrap_host);
         let crate_name = path.rsplit_once('/').unwrap().1;
-        run_cargo_test(cargo, &[], &[], crate_name, compiler, bootstrap_host, builder);
+        run_cargo_test(cargo, &[], &[], crate_name, crate_name, compiler, bootstrap_host, builder);
     }
 }
 
@@ -159,14 +158,6 @@ You can skip linkcheck with --exclude src/tools/linkchecker"
         let bootstrap_host = builder.config.build;
         let compiler = builder.compiler(0, bootstrap_host);
 
-        let self_test_group = builder.msg(
-            Kind::Test,
-            compiler.stage,
-            "linkchecker self tests",
-            bootstrap_host,
-            bootstrap_host,
-        );
-
         let cargo = tool::prepare_tool_cargo(
             builder,
             compiler,
@@ -177,8 +168,16 @@ You can skip linkcheck with --exclude src/tools/linkchecker"
             SourceType::InTree,
             &[],
         );
-        run_cargo_test(cargo, &[], &[], "linkchecker", compiler, bootstrap_host, builder);
-        drop(self_test_group);
+        run_cargo_test(
+            cargo,
+            &[],
+            &[],
+            "linkchecker",
+            "linkchecker self tests",
+            compiler,
+            bootstrap_host,
+            builder,
+        );
 
         if builder.doc_tests == DocTests::No {
             return;
@@ -413,8 +412,7 @@ impl Step for RustAnalyzer {
         cargo.env("SKIP_SLOW_TESTS", "1");
 
         cargo.add_rustc_lib_path(builder, compiler);
-        builder.msg_sysroot_tool(Kind::Test, compiler.stage, "rust-analyzer", host, host);
-        run_cargo_test(cargo, &[], &[], "rust-analyzer", compiler, host, builder);
+        run_cargo_test(cargo, &[], &[], "rust-analyzer", "rust-analyzer", compiler, host, builder);
     }
 }
 
@@ -463,8 +461,7 @@ impl Step for Rustfmt {
 
         cargo.add_rustc_lib_path(builder, compiler);
 
-        builder.msg_sysroot_tool(Kind::Test, compiler.stage, "rustfmt", host, host);
-        run_cargo_test(cargo, &[], &[], "rustfmt", compiler, host, builder);
+        run_cargo_test(cargo, &[], &[], "rustfmt", "rustfmt", compiler, host, builder);
     }
 }
 
@@ -512,7 +509,16 @@ impl Step for RustDemangler {
         cargo.env("RUST_DEMANGLER_DRIVER_PATH", rust_demangler);
         cargo.add_rustc_lib_path(builder, compiler);
 
-        run_cargo_test(cargo, &[], &[], "rust-demangler", compiler, host, builder);
+        run_cargo_test(
+            cargo,
+            &[],
+            &[],
+            "rust-demangler",
+            "rust-demangler",
+            compiler,
+            host,
+            builder,
+        );
     }
 }
 
@@ -754,7 +760,16 @@ impl Step for CompiletestTest {
             &[],
         );
         cargo.allow_features("test");
-        run_cargo_test(cargo, &[], &[], "compiletest", compiler, host, builder);
+        run_cargo_test(
+            cargo,
+            &[],
+            &[],
+            "compiletest",
+            "compiletest self test",
+            compiler,
+            host,
+            builder,
+        );
     }
 }
 
@@ -810,7 +825,7 @@ impl Step for Clippy {
             cargo.env("BLESS", "Gesundheit");
         }
 
-        builder.msg_sysroot_tool(Kind::Test, compiler.stage, "clippy", host, host);
+        let _guard = builder.msg_sysroot_tool(Kind::Test, compiler.stage, "clippy", host, host);
 
         if builder.try_run(&mut cargo).is_ok() {
             // The tests succeeded; nothing to do.
@@ -2201,11 +2216,12 @@ impl Step for CrateLibrustc {
 /// Given a `cargo test` subcommand, add the appropriate flags and run it.
 ///
 /// Returns whether the test succeeded.
-fn run_cargo_test(
+fn run_cargo_test<'a>(
     cargo: impl Into<Command>,
     libtest_args: &[&str],
     crates: &[Interned<String>],
     primary_crate: &str,
+    description: impl Into<Option<&'a str>>,
     compiler: Compiler,
     target: TargetSelection,
     builder: &Builder<'_>,
@@ -2213,6 +2229,9 @@ fn run_cargo_test(
     let mut cargo =
         prepare_cargo_test(cargo, libtest_args, crates, primary_crate, compiler, target, builder);
     let _time = util::timeit(&builder);
+    let _group = description.into().and_then(|what| {
+        builder.msg_sysroot_tool(Kind::Test, compiler.stage, what, compiler.host, target)
+    });
 
     #[cfg(feature = "build-metrics")]
     builder.metrics.begin_test_suite(
@@ -2378,14 +2397,16 @@ impl Step for Crate {
             _ => panic!("can only test libraries"),
         };
 
-        let _guard = builder.msg(
-            builder.kind,
-            compiler.stage,
-            crate_description(&self.crates),
-            compiler.host,
+        run_cargo_test(
+            cargo,
+            &[],
+            &self.crates,
+            &self.crates[0],
+            &*crate_description(&self.crates),
+            compiler,
             target,
+            builder,
         );
-        run_cargo_test(cargo, &[], &self.crates, &self.crates[0], compiler, target, builder);
     }
 }
 
@@ -2478,18 +2499,12 @@ impl Step for CrateRustdoc {
         dylib_path.insert(0, PathBuf::from(&*libdir));
         cargo.env(dylib_path_var(), env::join_paths(&dylib_path).unwrap());
 
-        let _guard = builder.msg_sysroot_tool(
-            builder.kind,
-            compiler.stage,
-            "rustdoc",
-            compiler.host,
-            target,
-        );
         run_cargo_test(
             cargo,
             &[],
             &[INTERNER.intern_str("rustdoc:0.0.0")],
             "rustdoc",
+            "rustdoc",
             compiler,
             target,
             builder,
@@ -2545,13 +2560,12 @@ impl Step for CrateRustdocJsonTypes {
             &[]
         };
 
-        let _guard =
-            builder.msg(builder.kind, compiler.stage, "rustdoc-json-types", compiler.host, target);
         run_cargo_test(
             cargo,
             libtest_args,
             &[INTERNER.intern_str("rustdoc-json-types")],
             "rustdoc-json-types",
+            "rustdoc-json-types",
             compiler,
             target,
             builder,
@@ -2722,7 +2736,7 @@ impl Step for Bootstrap {
         }
         // rustbuild tests are racy on directory creation so just run them one at a time.
         // Since there's not many this shouldn't be a problem.
-        run_cargo_test(cmd, &["--test-threads=1"], &[], "bootstrap", compiler, host, builder);
+        run_cargo_test(cmd, &["--test-threads=1"], &[], "bootstrap", None, compiler, host, builder);
     }
 
     fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
@@ -2840,14 +2854,16 @@ impl Step for RustInstaller {
             &[],
         );
 
-        let _guard = builder.msg(
-            Kind::Test,
-            compiler.stage,
+        run_cargo_test(
+            cargo,
+            &[],
+            &[],
+            "installer",
             "rust-installer",
+            compiler,
             bootstrap_host,
-            bootstrap_host,
+            builder,
         );
-        run_cargo_test(cargo, &[], &[], "installer", compiler, bootstrap_host, builder);
 
         // We currently don't support running the test.sh script outside linux(?) environments.
         // Eventually this should likely migrate to #[test]s in rust-installer proper rather than a