make it possible to use stage0 libtest on compiletest

bootstrap.example.toml

@@ -28,7 +28,7 @@
 #  - A new option
 #  - A change in the default values
 #
-# If the change-id does not match the version currently in use, x.py will 
+# If the change-id does not match the version currently in use, x.py will
 # display the changes made to the bootstrap.
 # To suppress these warnings, you can set change-id = "ignore".
 #change-id = <latest change id in src/bootstrap/src/utils/change_tracker.rs>
@@ -442,6 +442,9 @@
 # What custom diff tool to use for displaying compiletest tests.
 #compiletest-diff-tool = <none>
 
+# Whether to use the precompiled stage0 libtest with compiletest.
+#compiletest-use-stage0-libtest = true
+
 # Indicates whether ccache is used when building certain artifacts (e.g. LLVM).
 # Set to `true` to use the first `ccache` in PATH, or set an absolute path to use
 # a specific version.

src/bootstrap/defaults/bootstrap.dist.toml

@@ -7,6 +7,8 @@ test-stage = 2
 doc-stage = 2
 # When compiling from source, you usually want all tools.
 extended = true
+# Use libtest built from the source tree instead of the precompiled one from stage 0.
+compiletest-use-stage0-libtest = false
 
 # Most users installing from source want to build all parts of the project from source.
 [llvm]

src/bootstrap/src/core/build_steps/check.rs

@@ -369,6 +369,69 @@ impl Step for RustAnalyzer {
     }
 }
 
+/// Compiletest is implicitly "checked" when it gets built in order to run tests,
+/// so this is mainly for people working on compiletest to run locally.
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub struct Compiletest {
+    pub target: TargetSelection,
+}
+
+impl Step for Compiletest {
+    type Output = ();
+    const ONLY_HOSTS: bool = true;
+    const DEFAULT: bool = false;
+
+    fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
+        run.path("src/tools/compiletest")
+    }
+
+    fn make_run(run: RunConfig<'_>) {
+        run.builder.ensure(Compiletest { target: run.target });
+    }
+
+    fn run(self, builder: &Builder<'_>) {
+        let mode = if builder.config.compiletest_use_stage0_libtest {
+            Mode::ToolBootstrap
+        } else {
+            Mode::ToolStd
+        };
+
+        let compiler = builder.compiler(
+            if mode == Mode::ToolBootstrap { 0 } else { builder.top_stage },
+            builder.config.build,
+        );
+
+        if mode != Mode::ToolBootstrap {
+            builder.ensure(Rustc::new(self.target, builder));
+        }
+
+        let mut cargo = prepare_tool_cargo(
+            builder,
+            compiler,
+            mode,
+            self.target,
+            builder.kind,
+            "src/tools/compiletest",
+            SourceType::InTree,
+            &[],
+        );
+
+        cargo.allow_features("test");
+
+        // For ./x.py clippy, don't run with --all-targets because
+        // linting tests and benchmarks can produce very noisy results
+        if builder.kind != Kind::Clippy {
+            cargo.arg("--all-targets");
+        }
+
+        let stamp = BuildStamp::new(&builder.cargo_out(compiler, mode, self.target))
+            .with_prefix("compiletest-check");
+
+        let _guard = builder.msg_check("compiletest artifacts", self.target);
+        run_cargo(builder, cargo, builder.config.free_args.clone(), &stamp, vec![], true, false);
+    }
+}
+
 macro_rules! tool_check_step {
     (
         $name:ident {
@@ -464,7 +527,3 @@ tool_check_step!(Bootstrap { path: "src/bootstrap", default: false });
 // `run-make-support` will be built as part of suitable run-make compiletest test steps, but support
 // check to make it easier to work on.
 tool_check_step!(RunMakeSupport { path: "src/tools/run-make-support", default: false });
-
-// Compiletest is implicitly "checked" when it gets built in order to run tests,
-// so this is mainly for people working on compiletest to run locally.
-tool_check_step!(Compiletest { path: "src/tools/compiletest", default: false });

src/bootstrap/src/core/build_steps/compile.rs

@@ -2398,7 +2398,9 @@ pub fn run_cargo(
     // Ok now we need to actually find all the files listed in `toplevel`. We've
     // got a list of prefix/extensions and we basically just need to find the
     // most recent file in the `deps` folder corresponding to each one.
-    let contents = t!(target_deps_dir.read_dir())
+    let contents = target_deps_dir
+        .read_dir()
+        .unwrap_or_else(|e| panic!("Couldn't read {}: {}", target_deps_dir.display(), e))
         .map(|e| t!(e))
         .map(|e| (e.path(), e.file_name().into_string().unwrap(), t!(e.metadata())))
         .collect::<Vec<_>>();

src/bootstrap/src/core/build_steps/tool.rs

@@ -425,11 +425,14 @@ macro_rules! bootstrap_tool {
                     }
                 )*
 
+                let is_unstable = false $(|| $unstable)*;
+                let compiletest_wants_stage0 = $tool_name == "compiletest" && builder.config.compiletest_use_stage0_libtest;
+
                 builder.ensure(ToolBuild {
                     compiler: self.compiler,
                     target: self.target,
                     tool: $tool_name,
-                    mode: if false $(|| $unstable)* {
+                    mode: if is_unstable && !compiletest_wants_stage0 {
                         // use in-tree libraries for unstable features
                         Mode::ToolStd
                     } else {

src/bootstrap/src/core/config/config.rs

@@ -417,6 +417,9 @@ pub struct Config {
     /// Command for visual diff display, e.g. `diff-tool --color=always`.
     pub compiletest_diff_tool: Option<String>,
 
+    /// Whether to use the precompiled stage0 libtest with compiletest.
+    pub compiletest_use_stage0_libtest: bool,
+
     pub is_running_on_ci: bool,
 }
 
@@ -983,6 +986,7 @@ define_config! {
         optimized_compiler_builtins: Option<bool> = "optimized-compiler-builtins",
         jobs: Option<u32> = "jobs",
         compiletest_diff_tool: Option<String> = "compiletest-diff-tool",
+        compiletest_use_stage0_libtest: Option<bool> = "compiletest-use-stage0-libtest",
         ccache: Option<StringOrBool> = "ccache",
         exclude: Option<Vec<PathBuf>> = "exclude",
     }
@@ -1682,6 +1686,7 @@ impl Config {
             optimized_compiler_builtins,
             jobs,
             compiletest_diff_tool,
+            compiletest_use_stage0_libtest,
             mut ccache,
             exclude,
         } = toml.build.unwrap_or_default();
@@ -2415,6 +2420,7 @@ impl Config {
         config.optimized_compiler_builtins =
             optimized_compiler_builtins.unwrap_or(config.channel != "dev");
         config.compiletest_diff_tool = compiletest_diff_tool;
+        config.compiletest_use_stage0_libtest = compiletest_use_stage0_libtest.unwrap_or(true);
 
         let download_rustc = config.download_rustc_commit.is_some();
         config.explicit_stage_from_cli = flags.stage.is_some();

src/bootstrap/src/utils/change_tracker.rs

@@ -391,4 +391,9 @@ pub const CONFIG_CHANGE_HISTORY: &[ChangeInfo] = &[
         severity: ChangeSeverity::Info,
         summary: "You can now use `change-id = \"ignore\"` to suppress `change-id ` warnings in the console.",
     },
+    ChangeInfo {
+        change_id: 139386,
+        severity: ChangeSeverity::Info,
+        summary: "Added a new option `build.compiletest-use-stage0-libtest` to force `compiletest` to use the stage 0 libtest.",
+    },
 ];

src/ci/citool/tests/test-jobs.yml

@@ -27,7 +27,7 @@ runners:
     <<: *base-job
 envs:
   env-x86_64-apple-tests: &env-x86_64-apple-tests
-    SCRIPT: ./x.py --stage 2 test --skip tests/ui --skip tests/rustdoc -- --exact
+    SCRIPT: ./x.py check compiletest --set build.compiletest-use-stage0-libtest=true && ./x.py --stage 2 test --skip tests/ui --skip tests/rustdoc -- --exact
     RUST_CONFIGURE_ARGS: --build=x86_64-apple-darwin --enable-sanitizers --enable-profiler --set rust.jemalloc
     RUSTC_RETRY_LINKER_ON_SEGFAULT: 1
     # Ensure that host tooling is tested on our minimum supported macOS version.

src/ci/docker/host-x86_64/mingw-check/Dockerfile

@@ -47,6 +47,7 @@ COPY host-x86_64/mingw-check/validate-error-codes.sh /scripts/
 ENV SCRIPT \
            python3 ../x.py check --stage 0 --set build.optimized-compiler-builtins=false core alloc std --target=aarch64-unknown-linux-gnu,i686-pc-windows-msvc,i686-unknown-linux-gnu,x86_64-apple-darwin,x86_64-pc-windows-gnu,x86_64-pc-windows-msvc && \
            /scripts/check-default-config-profiles.sh && \
+           python3 ../x.py check compiletest --set build.compiletest-use-stage0-libtest=true && \
            python3 ../x.py check --target=x86_64-pc-windows-gnu --host=x86_64-pc-windows-gnu && \
            python3 ../x.py clippy ci && \
            python3 ../x.py build --stage 0 src/tools/build-manifest && \

src/ci/docker/host-x86_64/x86_64-gnu-tools/Dockerfile

@@ -101,4 +101,5 @@ COPY scripts/shared.sh /scripts/
 # the local version of the package is different than the one used by the CI.
 ENV SCRIPT /tmp/checktools.sh ../x.py && \
   npm install browser-ui-test@$(head -n 1 /tmp/browser-ui-test.version) --unsafe-perm=true && \
+  python3 ../x.py check compiletest --set build.compiletest-use-stage0-libtest=true && \
   python3 ../x.py test tests/rustdoc-gui --stage 2 --test-args "'--jobs 1'"

src/ci/github-actions/jobs.yml

@@ -58,7 +58,7 @@ runners:
     <<: *base-job
 envs:
   env-x86_64-apple-tests: &env-x86_64-apple-tests
-    SCRIPT: ./x.py --stage 2 test --skip tests/ui --skip tests/rustdoc -- --exact
+    SCRIPT: ./x.py check compiletest --set build.compiletest-use-stage0-libtest=true && ./x.py --stage 2 test --skip tests/ui --skip tests/rustdoc -- --exact
     RUST_CONFIGURE_ARGS: --build=x86_64-apple-darwin --enable-sanitizers --enable-profiler --set rust.jemalloc
     RUSTC_RETRY_LINKER_ON_SEGFAULT: 1
     # Ensure that host tooling is tested on our minimum supported macOS version.