From e759b97838f10b52163834315bf486d6972df3de Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jakub=20Ber=C3=A1nek?= <berykubik@gmail.com>
Date: Wed, 20 Aug 2025 15:04:47 +0200
Subject: [PATCH] Refactor `test::LintDocs`

---
 src/bootstrap/src/core/build_steps/doc.rs  |  6 ++++-
 src/bootstrap/src/core/build_steps/test.rs | 31 +++++++++++++++++-----
 src/bootstrap/src/core/builder/tests.rs    |  1 +
 3 files changed, 31 insertions(+), 7 deletions(-)

diff --git a/src/bootstrap/src/core/build_steps/doc.rs b/src/bootstrap/src/core/build_steps/doc.rs
index 9ef1fee1fecc..678fe127879b 100644
--- a/src/bootstrap/src/core/build_steps/doc.rs
+++ b/src/bootstrap/src/core/build_steps/doc.rs
@@ -791,7 +791,11 @@ fn doc_std(
 }
 
 /// Prepare a compiler that will be able to document something for `target` at `stage`.
-fn prepare_doc_compiler(builder: &Builder<'_>, target: TargetSelection, stage: u32) -> Compiler {
+pub fn prepare_doc_compiler(
+    builder: &Builder<'_>,
+    target: TargetSelection,
+    stage: u32,
+) -> Compiler {
     assert!(stage > 0, "Cannot document anything in stage 0");
     let build_compiler = builder.compiler(stage - 1, builder.host_target);
     builder.std(build_compiler, target);
diff --git a/src/bootstrap/src/core/build_steps/test.rs b/src/bootstrap/src/core/build_steps/test.rs
index e53638c81bdb..7c4256e9836a 100644
--- a/src/bootstrap/src/core/build_steps/test.rs
+++ b/src/bootstrap/src/core/build_steps/test.rs
@@ -12,7 +12,7 @@ use std::{env, fs, iter};
 use build_helper::exit;
 
 use crate::core::build_steps::compile::{Std, run_cargo};
-use crate::core::build_steps::doc::DocumentationFormat;
+use crate::core::build_steps::doc::{DocumentationFormat, prepare_doc_compiler};
 use crate::core::build_steps::gcc::{Gcc, add_cg_gcc_cargo_flags};
 use crate::core::build_steps::llvm::get_llvm_version;
 use crate::core::build_steps::run::get_completion_paths;
@@ -3304,8 +3304,8 @@ impl Step for TierCheck {
 
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct LintDocs {
-    pub compiler: Compiler,
-    pub target: TargetSelection,
+    build_compiler: Compiler,
+    target: TargetSelection,
 }
 
 impl Step for LintDocs {
@@ -3318,8 +3318,21 @@ impl Step for LintDocs {
     }
 
     fn make_run(run: RunConfig<'_>) {
+        // Bump the stage to 2, because the rustc book requires an in-tree compiler.
+        // At the same time, since this step is enabled by default, we don't want `x test` to fail
+        // in stage 1.
+        let stage = if run.builder.config.is_explicit_stage() || run.builder.top_stage >= 2 {
+            run.builder.top_stage
+        } else {
+            2
+        };
+
         run.builder.ensure(LintDocs {
-            compiler: run.builder.compiler(run.builder.top_stage, run.builder.config.host_target),
+            build_compiler: prepare_doc_compiler(
+                run.builder,
+                run.builder.config.host_target,
+                stage,
+            ),
             target: run.target,
         });
     }
@@ -3327,8 +3340,14 @@ impl Step for LintDocs {
     /// Tests that the lint examples in the rustc book generate the correct
     /// lints and have the expected format.
     fn run(self, builder: &Builder<'_>) {
-        builder
-            .ensure(crate::core::build_steps::doc::RustcBook::validate(self.compiler, self.target));
+        builder.ensure(crate::core::build_steps::doc::RustcBook::validate(
+            self.build_compiler,
+            self.target,
+        ));
+    }
+
+    fn metadata(&self) -> Option<StepMetadata> {
+        Some(StepMetadata::test("lint-docs", self.target).built_by(self.build_compiler))
     }
 }
 
diff --git a/src/bootstrap/src/core/builder/tests.rs b/src/bootstrap/src/core/builder/tests.rs
index 851e043a1c8e..ba6dfdff17a0 100644
--- a/src/bootstrap/src/core/builder/tests.rs
+++ b/src/bootstrap/src/core/builder/tests.rs
@@ -2093,6 +2093,7 @@ mod snapshot {
         [build] rustc 0 <host> -> Linkchecker 1 <host>
         [test] tier-check <host>
         [doc] rustc (book) <host>
+        [test] rustc 1 <host> -> lint-docs 2 <host>
         [doc] rustc 1 <host> -> std 1 <host> crates=[]
         [build] rustc 0 <host> -> RustdocTheme 1 <host>
         [test] RustdocUi <host>