Auto merge of #117484 - Zalathar:tests, r=cjgillot

coverage: Unify `tests/coverage-map` and `tests/run-coverage` into `tests/coverage`

Ever since the introduction of the `coverage-map` suite, it's been awkward to have to manage two separate coverage test directories containing dozens of mostly-identical files.

However, those two suites were separate for good reasons. They have very different requirements (since only one of them requires actually running the test program), running only one suite is noticeably faster than running both, and having separate suites allows them to be blessed separately if desired. So while unifying them was an obvious idea, actually doing so was non-trivial.

---

Nevertheless, this PR finds a way to merge the two suites into one directory while retaining almost all of the developer-experience benefits of having two suites. This required non-trivial implementations of `Step`, but the end result works very smoothly.

---

The first 5 commits are a copy of #117340, which has been closed in favour of this PR.

2 files changed, 100 insertions, 5 deletions

diff --git a/src/bootstrap/src/core/build_steps/test.rs b/src/bootstrap/src/core/build_steps/test.rs
index e2b515a3086..39667d16b7b 100644
--- a/src/bootstrap/src/core/build_steps/test.rs
+++ b/src/bootstrap/src/core/build_steps/test.rs
@@ -1305,6 +1305,47 @@ macro_rules! test_definitions {
     };
 }
 
+/// Declares an alias for running the [`Coverage`] tests in only one mode.
+/// Adapted from [`test_definitions`].
+macro_rules! coverage_test_alias {
+    ($name:ident {
+        alias_and_mode: $alias_and_mode:expr,
+        default: $default:expr,
+        only_hosts: $only_hosts:expr $(,)?
+    }) => {
+        #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
+        pub struct $name {
+            pub compiler: Compiler,
+            pub target: TargetSelection,
+        }
+
+        impl $name {
+            const MODE: &'static str = $alias_and_mode;
+        }
+
+        impl Step for $name {
+            type Output = ();
+            const DEFAULT: bool = $default;
+            const ONLY_HOSTS: bool = $only_hosts;
+
+            fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
+                run.alias($alias_and_mode)
+            }
+
+            fn make_run(run: RunConfig<'_>) {
+                let compiler = run.builder.compiler(run.builder.top_stage, run.build_triple());
+
+                run.builder.ensure($name { compiler, target: run.target });
+            }
+
+            fn run(self, builder: &Builder<'_>) {
+                Coverage { compiler: self.compiler, target: self.target }
+                    .run_unified_suite(builder, Self::MODE)
+            }
+        }
+    };
+}
+
 default_test!(Ui { path: "tests/ui", mode: "ui", suite: "ui" });
 
 default_test!(RunPassValgrind {
@@ -1349,13 +1390,66 @@ host_test!(RunMakeFullDeps {
 
 default_test!(Assembly { path: "tests/assembly", mode: "assembly", suite: "assembly" });
 
-default_test!(CoverageMap {
-    path: "tests/coverage-map",
-    mode: "coverage-map",
-    suite: "coverage-map"
+/// Custom test step that is responsible for running the coverage tests
+/// in multiple different modes.
+///
+/// Each individual mode also has its own alias that will run the tests in
+/// just that mode.
+#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
+pub struct Coverage {
+    pub compiler: Compiler,
+    pub target: TargetSelection,
+}
+
+impl Coverage {
+    const PATH: &'static str = "tests/coverage";
+    const SUITE: &'static str = "coverage";
+
+    fn run_unified_suite(&self, builder: &Builder<'_>, mode: &'static str) {
+        builder.ensure(Compiletest {
+            compiler: self.compiler,
+            target: self.target,
+            mode,
+            suite: Self::SUITE,
+            path: Self::PATH,
+            compare_mode: None,
+        })
+    }
+}
+
+impl Step for Coverage {
+    type Output = ();
+    const DEFAULT: bool = false;
+    const ONLY_HOSTS: bool = false;
+
+    fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
+        run.suite_path(Self::PATH)
+    }
+
+    fn make_run(run: RunConfig<'_>) {
+        let compiler = run.builder.compiler(run.builder.top_stage, run.build_triple());
+
+        run.builder.ensure(Coverage { compiler, target: run.target });
+    }
+
+    fn run(self, builder: &Builder<'_>) {
+        self.run_unified_suite(builder, CoverageMap::MODE);
+        self.run_unified_suite(builder, RunCoverage::MODE);
+    }
+}
+
+// Aliases for running the coverage tests in only one mode.
+coverage_test_alias!(CoverageMap {
+    alias_and_mode: "coverage-map",
+    default: true,
+    only_hosts: false,
+});
+coverage_test_alias!(RunCoverage {
+    alias_and_mode: "run-coverage",
+    default: true,
+    only_hosts: true,
 });
 
-host_test!(RunCoverage { path: "tests/run-coverage", mode: "run-coverage", suite: "run-coverage" });
 host_test!(RunCoverageRustdoc {
     path: "tests/run-coverage-rustdoc",
     mode: "run-coverage",
diff --git a/src/bootstrap/src/core/builder.rs b/src/bootstrap/src/core/builder.rs
index 44cdbe38de3..38eb4633273 100644
--- a/src/bootstrap/src/core/builder.rs
+++ b/src/bootstrap/src/core/builder.rs
@@ -727,6 +727,7 @@ impl<'a> Builder<'a> {
                 test::Tidy,
                 test::Ui,
                 test::RunPassValgrind,
+                test::Coverage,
                 test::CoverageMap,
                 test::RunCoverage,
                 test::MirOpt,