Fix handling of std crates for no_std targets

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

@@ -449,21 +449,24 @@ fn copy_self_contained_objects(
     target_deps
 }
 
-/// Resolves standard library crates for `Std::run_make` for any build kind (like check, build, clippy, etc.).
+/// Resolves standard library crates for `Std::run_make` for any build kind (like check, doc,
+/// build, clippy, etc.).
 pub fn std_crates_for_run_make(run: &RunConfig<'_>) -> Vec<String> {
-    let has_alias = run.paths.iter().any(|set| set.assert_single_path().path.ends_with("library"));
-    let target_is_no_std = run.builder.no_std(run.target).unwrap_or(false);
+    let mut crates = run.make_run_crates(builder::Alias::Library);
 
-    // For no_std targets, do not add any additional crates to the compilation other than what `compile::std_cargo` already adds for no_std targets.
+    // For no_std targets, we only want to check core and alloc
+    // Regardless of core/alloc being selected explicitly or via the "library" default alias,
+    // we only want to keep these two crates.
+    // The set of no_std crates should be kept in sync with what `Builder::std_cargo` does.
+    // Note: an alternative design would be to return an enum from this function (Default vs Subset)
+    // of crates. However, several steps currently pass `-p <package>` even if all crates are
+    // selected, because Cargo behaves differently in that case. To keep that behavior without
+    // making further changes, we pre-filter the no-std crates here.
+    let target_is_no_std = run.builder.no_std(run.target).unwrap_or(false);
     if target_is_no_std {
-        vec![]
-    }
-    // If the paths include "library", build the entire standard library.
-    else if has_alias {
-        run.make_run_crates(builder::Alias::Library)
-    } else {
-        run.cargo_crates_in_set()
+        crates.retain(|c| c == "core" || c == "alloc");
     }
+    crates
 }
 
 /// Tries to find LLVM's `compiler-rt` source directory, for building `library/profiler_builtins`.

src/bootstrap/src/core/builder/tests.rs

@@ -637,8 +637,8 @@ mod snapshot {
 
     use crate::core::build_steps::{compile, dist, doc, test, tool};
     use crate::core::builder::tests::{
-        TEST_TRIPLE_1, TEST_TRIPLE_2, TEST_TRIPLE_3, configure, configure_with_args, first,
-        host_target, render_steps, run_build,
+        RenderConfig, TEST_TRIPLE_1, TEST_TRIPLE_2, TEST_TRIPLE_3, configure, configure_with_args,
+        first, host_target, render_steps, run_build,
     };
     use crate::core::builder::{Builder, Kind, StepDescription, StepMetadata};
     use crate::core::config::TargetSelection;
@@ -1521,6 +1521,49 @@ mod snapshot {
         steps.assert_contains(StepMetadata::test("CrateLibrustc", host));
         steps.assert_contains_fuzzy(StepMetadata::build("rustc", host));
     }
+
+    #[test]
+    fn doc_library() {
+        let ctx = TestCtx::new();
+        insta::assert_snapshot!(
+            ctx.config("doc")
+                .path("library")
+                .render_steps(), @r"
+        [build] llvm <host>
+        [build] rustc 0 <host> -> rustc 1 <host>
+        [build] rustdoc 0 <host>
+        [doc] std 1 <host> crates=[alloc,compiler_builtins,core,panic_abort,panic_unwind,proc_macro,std,sysroot,test,unwind]
+        ");
+    }
+
+    #[test]
+    fn doc_core() {
+        let ctx = TestCtx::new();
+        insta::assert_snapshot!(
+            ctx.config("doc")
+                .path("core")
+                .render_steps(), @r"
+        [build] llvm <host>
+        [build] rustc 0 <host> -> rustc 1 <host>
+        [build] rustdoc 0 <host>
+        [doc] std 1 <host> crates=[core]
+        ");
+    }
+
+    #[test]
+    fn doc_library_no_std_target() {
+        let ctx = TestCtx::new();
+        insta::assert_snapshot!(
+            ctx.config("doc")
+                .path("core")
+                .override_target_no_std(&host_target())
+                .render_steps(), @r"
+        [build] llvm <host>
+        [build] rustc 0 <host> -> rustc 1 <host>
+        [build] rustdoc 0 <host>
+        [doc] std 1 <host> crates=[core]
+        ");
+    }
 }
 
 struct ExecutedSteps {
@@ -1529,7 +1572,10 @@ struct ExecutedSteps {
 
 impl ExecutedSteps {
     fn render(&self) -> String {
-        render_steps(&self.steps)
+        self.render_with(RenderConfig::default())
+    }
+    fn render_with(&self, config: RenderConfig) -> String {
+        render_steps(&self.steps, config)
     }
 
     #[track_caller]
@@ -1538,7 +1584,7 @@ impl ExecutedSteps {
         if !self.contains(&metadata) {
             panic!(
                 "Metadata `{}` ({metadata:?}) not found in executed steps:\n{}",
-                render_metadata(&metadata),
+                render_metadata(&metadata, &RenderConfig::default()),
                 self.render()
             );
         }
@@ -1553,7 +1599,7 @@ impl ExecutedSteps {
         if !self.contains_fuzzy(&metadata) {
             panic!(
                 "Metadata `{}` ({metadata:?}) not found in executed steps:\n{}",
-                render_metadata(&metadata),
+                render_metadata(&metadata, &RenderConfig::default()),
                 self.render()
             );
         }
@@ -1565,7 +1611,7 @@ impl ExecutedSteps {
         if self.contains(&metadata) {
             panic!(
                 "Metadata `{}` ({metadata:?}) found in executed steps (it should not be there):\n{}",
-                render_metadata(&metadata),
+                render_metadata(&metadata, &RenderConfig::default()),
                 self.render()
             );
         }
@@ -1618,6 +1664,16 @@ impl ConfigBuilder {
     }
 }
 
+struct RenderConfig {
+    normalize_host: bool,
+}
+
+impl Default for RenderConfig {
+    fn default() -> Self {
+        Self { normalize_host: true }
+    }
+}
+
 /// Renders the executed bootstrap steps for usage in snapshot tests with insta.
 /// Only renders certain important steps.
 /// Each value in `steps` should be a tuple of (Step, step output).
@@ -1625,7 +1681,7 @@ impl ConfigBuilder {
 /// The arrow in the rendered output (`X -> Y`) means `X builds Y`.
 /// This is similar to the output printed by bootstrap to stdout, but here it is
 /// generated purely for the purpose of tests.
-fn render_steps(steps: &[ExecutedStep]) -> String {
+fn render_steps(steps: &[ExecutedStep], config: RenderConfig) -> String {
     steps
         .iter()
         .filter_map(|step| {
@@ -1635,35 +1691,35 @@ fn render_steps(steps: &[ExecutedStep]) -> String {
                 return None;
             };
 
-            Some(render_metadata(&metadata))
+            Some(render_metadata(&metadata, &config))
         })
         .collect::<Vec<_>>()
         .join("\n")
 }
 
-fn render_metadata(metadata: &StepMetadata) -> String {
+fn render_metadata(metadata: &StepMetadata, config: &RenderConfig) -> String {
     let mut record = format!("[{}] ", metadata.kind.as_str());
     if let Some(compiler) = metadata.built_by {
-        write!(record, "{} -> ", render_compiler(compiler));
+        write!(record, "{} -> ", render_compiler(compiler, config));
     }
     let stage = metadata.get_stage().map(|stage| format!("{stage} ")).unwrap_or_default();
-    write!(record, "{} {stage}<{}>", metadata.name, normalize_target(metadata.target));
+    write!(record, "{} {stage}<{}>", metadata.name, normalize_target(metadata.target, config));
     if let Some(metadata) = &metadata.metadata {
         write!(record, " {metadata}");
     }
     record
 }
 
-fn normalize_target(target: TargetSelection) -> String {
-    target
-        .to_string()
-        .replace(&host_target(), "host")
-        .replace(TEST_TRIPLE_1, "target1")
-        .replace(TEST_TRIPLE_2, "target2")
+fn normalize_target(target: TargetSelection, config: &RenderConfig) -> String {
+    let mut target = target.to_string();
+    if config.normalize_host {
+        target = target.replace(&host_target(), "host");
+    }
+    target.replace(TEST_TRIPLE_1, "target1").replace(TEST_TRIPLE_2, "target2")
 }
 
-fn render_compiler(compiler: Compiler) -> String {
-    format!("rustc {} <{}>", compiler.stage, normalize_target(compiler.host))
+fn render_compiler(compiler: Compiler, config: &RenderConfig) -> String {
+    format!("rustc {} <{}>", compiler.stage, normalize_target(compiler.host, config))
 }
 
 fn host_target() -> String {

src/bootstrap/src/utils/tests/mod.rs

@@ -48,17 +48,30 @@ impl ConfigBuilder {
     }
 
     pub fn path(mut self, path: &str) -> Self {
-        self.args.push(path.to_string());
-        self
+        self.arg(path)
     }
 
     pub fn paths(mut self, paths: &[&str]) -> Self {
-        for path in paths {
-            self = self.path(path);
+        self.args(paths)
+    }
+
+    pub fn arg(mut self, arg: &str) -> Self {
+        self.args.push(arg.to_string());
+        self
+    }
+
+    pub fn args(mut self, args: &[&str]) -> Self {
+        for arg in args {
+            self = self.arg(arg);
         }
         self
     }
 
+    /// Set the specified target to be treated as a no_std target.
+    pub fn override_target_no_std(mut self, target: &str) -> Self {
+        self.args(&["--set", &format!("target.{target}.no-std=true")])
+    }
+
     pub fn hosts(mut self, targets: &[&str]) -> Self {
         self.args.push("--host".to_string());
         self.args.push(targets.join(","));
@@ -77,13 +90,6 @@ impl ConfigBuilder {
         self
     }
 
-    pub fn args(mut self, args: &[&str]) -> Self {
-        for arg in args {
-            self.args.push(arg.to_string());
-        }
-        self
-    }
-
     pub fn create_config(mut self) -> Config {
         // Run in dry-check, otherwise the test would be too slow
         self.args.push("--dry-run".to_string());