Rollup merge of #141914 - onur-ozkan:follow-ups, r=Kobzol

redesign stage 0 std follow-ups

Various follow-ups pointed out on Zulip during post-merge discussions of [redesign stage 0 std #119899](https://github.com/rust-lang/rust/pull/119899).

r? `@jieyouxu`

Fixes https://github.com/rust-lang/rust/issues/141902.
Fixes https://github.com/rust-lang/rust/issues/141905.

cc `@jyn514`

5 files changed, 56 insertions, 18 deletions

diff --git a/src/bootstrap/defaults/bootstrap.library.toml b/src/bootstrap/defaults/bootstrap.library.toml
index 6edd00922ae..895e50b9a20 100644
--- a/src/bootstrap/defaults/bootstrap.library.toml
+++ b/src/bootstrap/defaults/bootstrap.library.toml
@@ -1,8 +1,9 @@
 # These defaults are meant for contributors to the standard library and documentation.
 [build]
+bench-stage = 1
 build-stage = 1
+check-stage = 1
 test-stage = 1
-bench-stage = 1
 
 [rust]
 # This greatly increases the speed of rebuilds, especially when there are only minor changes. However, it makes the initial build slightly slower.
diff --git a/src/bootstrap/src/core/build_steps/check.rs b/src/bootstrap/src/core/build_steps/check.rs
index 922578f309a..f30e26d9cc2 100644
--- a/src/bootstrap/src/core/build_steps/check.rs
+++ b/src/bootstrap/src/core/build_steps/check.rs
@@ -31,6 +31,8 @@ pub struct Std {
 }
 
 impl Std {
+    const CRATE_OR_DEPS: &[&str] = &["sysroot", "coretests", "alloctests"];
+
     pub fn new(target: TargetSelection) -> Self {
         Self { target, crates: vec![], override_build_kind: None }
     }
@@ -46,12 +48,19 @@ impl Step for Std {
     const DEFAULT: bool = true;
 
     fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
-        let stage = run.builder.top_stage;
-        run.crate_or_deps("sysroot")
-            .crate_or_deps("coretests")
-            .crate_or_deps("alloctests")
-            .path("library")
-            .default_condition(stage != 0)
+        let builder = run.builder;
+        let stage = if builder.config.is_explicit_stage() || builder.top_stage >= 1 {
+            builder.top_stage
+        } else {
+            1
+        };
+
+        let mut run = run;
+        for c in Std::CRATE_OR_DEPS {
+            run = run.crate_or_deps(c);
+        }
+
+        run.path("library").default_condition(stage != 0)
     }
 
     fn make_run(run: RunConfig<'_>) {
@@ -62,10 +71,29 @@ impl Step for Std {
     fn run(self, builder: &Builder<'_>) {
         builder.require_submodule("library/stdarch", None);
 
+        let stage = if builder.config.is_explicit_stage() || builder.top_stage >= 1 {
+            builder.top_stage
+        } else {
+            1
+        };
+
         let target = self.target;
-        let compiler = builder.compiler(builder.top_stage, builder.config.build);
+        let compiler = builder.compiler(stage, builder.config.build);
+
+        if stage == 0 {
+            let mut is_explicitly_called =
+                builder.paths.iter().any(|p| p.starts_with("library") || p.starts_with("std"));
+
+            if !is_explicitly_called {
+                for c in Std::CRATE_OR_DEPS {
+                    is_explicitly_called = builder.paths.iter().any(|p| p.starts_with(c));
+                }
+            }
+
+            if is_explicitly_called {
+                eprintln!("WARNING: stage 0 std is precompiled and does nothing during `x check`.");
+            }
 
-        if builder.top_stage == 0 {
             // Reuse the stage0 libstd
             builder.ensure(compile::Std::new(compiler, target));
             return;
@@ -93,6 +121,7 @@ impl Step for Std {
         let _guard = builder.msg_check(
             format_args!("library artifacts{}", crate_description(&self.crates)),
             target,
+            Some(stage),
         );
 
         let stamp = build_stamp::libstd_stamp(builder, compiler, target).with_prefix("check");
@@ -145,7 +174,7 @@ impl Step for Std {
         }
 
         let stamp = build_stamp::libstd_stamp(builder, compiler, target).with_prefix("check-test");
-        let _guard = builder.msg_check("library test/bench/example targets", target);
+        let _guard = builder.msg_check("library test/bench/example targets", target, Some(stage));
         run_cargo(builder, cargo, builder.config.free_args.clone(), &stamp, vec![], true, false);
     }
 }
@@ -246,6 +275,7 @@ impl Step for Rustc {
         let _guard = builder.msg_check(
             format_args!("compiler artifacts{}", crate_description(&self.crates)),
             target,
+            None,
         );
 
         let stamp = build_stamp::librustc_stamp(builder, compiler, target).with_prefix("check");
@@ -306,7 +336,7 @@ impl Step for CodegenBackend {
             .arg(builder.src.join(format!("compiler/rustc_codegen_{backend}/Cargo.toml")));
         rustc_cargo_env(builder, &mut cargo, target, compiler.stage);
 
-        let _guard = builder.msg_check(backend, target);
+        let _guard = builder.msg_check(backend, target, None);
 
         let stamp = build_stamp::codegen_backend_stamp(builder, compiler, target, backend)
             .with_prefix("check");
@@ -373,7 +403,7 @@ impl Step for RustAnalyzer {
         let stamp = BuildStamp::new(&builder.cargo_out(compiler, Mode::ToolRustc, target))
             .with_prefix("rust-analyzer-check");
 
-        let _guard = builder.msg_check("rust-analyzer artifacts", target);
+        let _guard = builder.msg_check("rust-analyzer artifacts", target, None);
         run_cargo(builder, cargo, builder.config.free_args.clone(), &stamp, vec![], true, false);
     }
 }
@@ -436,7 +466,7 @@ impl Step for Compiletest {
         let stamp = BuildStamp::new(&builder.cargo_out(compiler, mode, self.target))
             .with_prefix("compiletest-check");
 
-        let _guard = builder.msg_check("compiletest artifacts", self.target);
+        let _guard = builder.msg_check("compiletest artifacts", self.target, None);
         run_cargo(builder, cargo, builder.config.free_args.clone(), &stamp, vec![], true, false);
     }
 }
@@ -514,7 +544,7 @@ fn run_tool_check_step(
     let stamp = BuildStamp::new(&builder.cargo_out(compiler, Mode::ToolRustc, target))
         .with_prefix(&format!("{}-check", step_type_name.to_lowercase()));
 
-    let _guard = builder.msg_check(format!("{display_name} artifacts"), target);
+    let _guard = builder.msg_check(format!("{display_name} artifacts"), target, None);
     run_cargo(builder, cargo, builder.config.free_args.clone(), &stamp, vec![], true, false);
 }
 
diff --git a/src/bootstrap/src/core/config/config.rs b/src/bootstrap/src/core/config/config.rs
index 899ffde8adf..03044d4fc80 100644
--- a/src/bootstrap/src/core/config/config.rs
+++ b/src/bootstrap/src/core/config/config.rs
@@ -2531,9 +2531,8 @@ impl Config {
             || bench_stage.is_some();
         // See https://github.com/rust-lang/compiler-team/issues/326
         config.stage = match config.cmd {
-            Subcommand::Check { .. } | Subcommand::Clippy { .. } | Subcommand::Fix => {
-                flags.stage.or(check_stage).unwrap_or(1)
-            }
+            Subcommand::Check { .. } => flags.stage.or(check_stage).unwrap_or(0),
+            Subcommand::Clippy { .. } | Subcommand::Fix => flags.stage.or(check_stage).unwrap_or(1),
             // `download-rustc` only has a speed-up for stage2 builds. Default to stage2 unless explicitly overridden.
             Subcommand::Doc { .. } => {
                 flags.stage.or(doc_stage).unwrap_or(if download_rustc { 2 } else { 1 })
diff --git a/src/bootstrap/src/lib.rs b/src/bootstrap/src/lib.rs
index e4643653d97..cfb968f79ba 100644
--- a/src/bootstrap/src/lib.rs
+++ b/src/bootstrap/src/lib.rs
@@ -1104,8 +1104,15 @@ Executed at: {executed_at}"#,
         &self,
         what: impl Display,
         target: impl Into<Option<TargetSelection>>,
+        custom_stage: Option<u32>,
     ) -> Option<gha::Group> {
-        self.msg(Kind::Check, self.config.stage, what, self.config.build, target)
+        self.msg(
+            Kind::Check,
+            custom_stage.unwrap_or(self.config.stage),
+            what,
+            self.config.build,
+            target,
+        )
     }
 
     #[must_use = "Groups should not be dropped until the Step finishes running"]
diff --git a/src/ci/docker/host-x86_64/mingw-check-2/Dockerfile b/src/ci/docker/host-x86_64/mingw-check-2/Dockerfile
index 0c75f116aa0..11a66a1c013 100644
--- a/src/ci/docker/host-x86_64/mingw-check-2/Dockerfile
+++ b/src/ci/docker/host-x86_64/mingw-check-2/Dockerfile
@@ -27,6 +27,7 @@ COPY scripts/sccache.sh /scripts/
 RUN sh /scripts/sccache.sh
 
 ENV SCRIPT \
+        python3 ../x.py check && \
         python3 ../x.py clippy ci && \
         python3 ../x.py test --stage 1 core alloc std test proc_macro && \
         # Build both public and internal documentation.