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

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",

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,

src/tools/compiletest/src/common.rs

@@ -78,14 +78,23 @@ impl Default for Mode {
 }
 
 impl Mode {
-    pub fn disambiguator(self) -> &'static str {
+    pub fn aux_dir_disambiguator(self) -> &'static str {
         // Pretty-printing tests could run concurrently, and if they do,
         // they need to keep their output segregated.
         match self {
             Pretty => ".pretty",
             _ => "",
         }
     }
+
+    pub fn output_dir_disambiguator(self) -> &'static str {
+        // Coverage tests use the same test files for multiple test modes,
+        // so each mode should have a separate output directory.
+        match self {
+            CoverageMap | RunCoverage => self.to_str(),
+            _ => "",
+        }
+    }
 }
 
 string_enum! {
@@ -699,6 +708,7 @@ pub fn output_testname_unique(
     let mode = config.compare_mode.as_ref().map_or("", |m| m.to_str());
     let debugger = config.debugger.as_ref().map_or("", |m| m.to_str());
     PathBuf::from(&testpaths.file.file_stem().unwrap())
+        .with_extra_extension(config.mode.output_dir_disambiguator())
         .with_extra_extension(revision.unwrap_or(""))
         .with_extra_extension(mode)
         .with_extra_extension(debugger)

src/tools/compiletest/src/runtest.rs

@@ -2193,7 +2193,7 @@ impl<'test> TestCx<'test> {
             || self.is_vxworks_pure_static()
             || self.config.target.contains("bpf")
             || !self.config.target_cfg().dynamic_linking
-            || self.config.mode == RunCoverage
+            || matches!(self.config.mode, CoverageMap | RunCoverage)
         {
             // We primarily compile all auxiliary libraries as dynamic libraries
             // to avoid code size bloat and large binaries as much as possible
@@ -2481,9 +2481,9 @@ impl<'test> TestCx<'test> {
             RunCoverage => {
                 rustc.arg("-Cinstrument-coverage");
                 // Coverage reports are sometimes sensitive to optimizations,
-                // and the current snapshots assume no optimization unless
+                // and the current snapshots assume `opt-level=2` unless
                 // overridden by `compile-flags`.
-                rustc.arg("-Copt-level=0");
+                rustc.arg("-Copt-level=2");
             }
             RunPassValgrind | Pretty | DebugInfo | Codegen | Rustdoc | RustdocJson | RunMake
             | CodegenUnits | JsDocTest | Assembly => {
@@ -2720,7 +2720,7 @@ impl<'test> TestCx<'test> {
     fn aux_output_dir_name(&self) -> PathBuf {
         self.output_base_dir()
             .join("auxiliary")
-            .with_extra_extension(self.config.mode.disambiguator())
+            .with_extra_extension(self.config.mode.aux_dir_disambiguator())
     }
 
     /// Generates a unique name for the test, such as `testname.revision.mode`.

tests/coverage/README.md

@@ -0,0 +1,16 @@
+The tests in this directory are shared by two different test modes, and can be
+run in multiple different ways:
+
+- `./x.py test coverage-map` (compiles to LLVM IR and checks coverage mappings)
+- `./x.py test run-coverage` (runs a test binary and checks its coverage report)
+- `./x.py test coverage` (runs both `coverage-map` and `run-coverage`)
+
+## Maintenance note
+
+These tests can be sensitive to small changes in MIR spans or MIR control flow,
+especially in HIR-to-MIR lowering or MIR optimizations.
+
+If you haven't touched the coverage code directly, and the tests still pass in
+`run-coverage` mode, then it should usually be OK to just re-bless the mappings
+as necessary with `./x.py test coverage-map --bless`, without worrying too much
+about the exact changes.

tests/coverage/issue-85461.cov-map

@@ -0,0 +1,8 @@
+Function name: issue_85461::main
+Raw bytes (9): 0x[01, 01, 00, 01, 01, 08, 01, 03, 02]
+Number of files: 1
+- file 0 => global file 1
+Number of expressions: 0
+Number of file 0 mappings: 1
+- Code(Counter(0)) at (prev + 8, 1) to (start + 3, 2)
+