Add support for run-make-support unit tests to be run with bootstrap …

…command

src/bootstrap/src/core/build_steps/test.rs

@@ -1371,6 +1371,7 @@ impl Step for RunMakeSupport {
         run.builder.ensure(RunMakeSupport { compiler, target: run.build_triple() });
     }
 
+    /// Builds run-make-support and returns the path to the resulting rlib.
     fn run(self, builder: &Builder<'_>) -> PathBuf {
         builder.ensure(compile::Std::new(self.compiler, self.target));
 
@@ -1397,6 +1398,52 @@ impl Step for RunMakeSupport {
     }
 }
 
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub struct RunMakeSupportTest {
+    host: TargetSelection,
+}
+
+impl Step for RunMakeSupportTest {
+    type Output = ();
+
+    fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
+        run.path("src/tools/run-make-support")
+    }
+
+    fn make_run(run: RunConfig<'_>) {
+        run.builder.ensure(RunMakeSupportTest { host: run.target });
+    }
+
+    /// Runs `cargo test` for run-make-support.
+    fn run(self, builder: &Builder<'_>) {
+        let host = self.host;
+        let compiler = builder.compiler(builder.top_stage, host);
+
+        builder.ensure(compile::Std::new(compiler, host));
+        let mut cargo = tool::prepare_tool_cargo(
+            builder,
+            compiler,
+            Mode::ToolStd,
+            host,
+            "test",
+            "src/tools/run-make-support",
+            SourceType::InTree,
+            &[],
+        );
+        cargo.allow_features("test");
+        run_cargo_test(
+            cargo,
+            &[],
+            &[],
+            "run-make-support",
+            "run-make-support self test",
+            compiler,
+            host,
+            builder,
+        );
+    }
+}
+
 default_test!(Ui { path: "tests/ui", mode: "ui", suite: "ui" });
 
 default_test!(Crashes { path: "tests/crashes", mode: "crashes", suite: "crashes" });

src/bootstrap/src/core/builder.rs

@@ -829,6 +829,7 @@ impl<'a> Builder<'a> {
                 test::Bootstrap,
                 // Run run-make last, since these won't pass without make on Windows
                 test::RunMake,
+                test::RunMakeSupportTest,
             ),
             Kind::Miri => describe!(test::Crate),
             Kind::Bench => describe!(test::Crate, test::CrateLibrustc),