Allow checking individual crates

This is useful for profiling metadata generation.

This comes very close to removing all_krates, but doesn't quite -
there's one last usage left in `doc`.

Author: jyn514

src/bootstrap/check.rs

@@ -1,6 +1,6 @@
 //! Implementation of compiling the compiler and standard library, in "check"-based modes.
 
-use crate::builder::{Builder, Kind, RunConfig, ShouldRun, Step};
+use crate::builder::{crate_description, Builder, Kind, RunConfig, ShouldRun, Step};
 use crate::cache::Interned;
 use crate::compile::{add_to_sysroot, run_cargo, rustc_cargo, rustc_cargo_env, std_cargo};
 use crate::config::TargetSelection;
@@ -12,6 +12,12 @@ use std::path::{Path, PathBuf};
 #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
 pub struct Std {
     pub target: TargetSelection,
+    /// Whether to build only a subset of crates.
+    ///
+    /// This shouldn't be used from other steps; see the comment on [`compile::Rustc`].
+    ///
+    /// [`compile::Rustc`]: crate::compile::Rustc
+    crates: Interned<Vec<String>>,
 }
 
 /// Returns args for the subcommand itself (not for cargo)
@@ -66,16 +72,24 @@ fn cargo_subcommand(kind: Kind) -> &'static str {
     }
 }
 
+impl Std {
+    pub fn new(target: TargetSelection) -> Self {
+        Self { target, crates: INTERNER.intern_list(vec![]) }
+    }
+}
+
 impl Step for Std {
     type Output = ();
     const DEFAULT: bool = true;
 
     fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
-        run.all_krates("sysroot").path("library")
+        let crates = run.builder.in_tree_crates("sysroot", None);
+        run.crates(crates).path("library")
     }
 
     fn make_run(run: RunConfig<'_>) {
-        run.builder.ensure(Std { target: run.target });
+        let crates = run.cargo_crates_in_set();
+        run.builder.ensure(Std { target: run.target, crates });
     }
 
     fn run(self, builder: &Builder<'_>) {
@@ -97,7 +111,14 @@ impl Step for Std {
             cargo.arg("--lib");
         }
 
-        let _guard = builder.msg_check("library artifacts", target);
+        for krate in &*self.crates {
+            cargo.arg("-p").arg(krate);
+        }
+
+        let _guard = builder.msg_check(
+            format_args!("library artifacts{}", crate_description(&self.crates)),
+            target,
+        );
         run_cargo(
             builder,
             cargo,
@@ -117,7 +138,8 @@ impl Step for Std {
         }
 
         // don't run on std twice with x.py clippy
-        if builder.kind == Kind::Clippy {
+        // don't check test dependencies if we haven't built libtest
+        if builder.kind == Kind::Clippy || !self.crates.is_empty() {
             return;
         }
 
@@ -147,8 +169,8 @@ impl Step for Std {
         // Explicitly pass -p for all dependencies krates -- this will force cargo
         // to also check the tests/benches/examples for these crates, rather
         // than just the leaf crate.
-        for krate in builder.in_tree_crates("test", Some(target)) {
-            cargo.arg("-p").arg(krate.name);
+        for krate in &*self.crates {
+            cargo.arg("-p").arg(krate);
         }
 
         let _guard = builder.msg_check("library test/bench/example targets", target);
@@ -167,6 +189,22 @@ impl Step for Std {
 #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
 pub struct Rustc {
     pub target: TargetSelection,
+    /// Whether to build only a subset of crates.
+    ///
+    /// This shouldn't be used from other steps; see the comment on [`compile::Rustc`].
+    ///
+    /// [`compile::Rustc`]: crate::compile::Rustc
+    crates: Interned<Vec<String>>,
+}
+
+impl Rustc {
+    pub fn new(target: TargetSelection, builder: &Builder<'_>) -> Self {
+        let mut crates = vec![];
+        for krate in builder.in_tree_crates("rustc-main", None) {
+            crates.push(krate.name.to_string());
+        }
+        Self { target, crates: INTERNER.intern_list(crates) }
+    }
 }
 
 impl Step for Rustc {
@@ -175,11 +213,13 @@ impl Step for Rustc {
     const DEFAULT: bool = true;
 
     fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
-        run.all_krates("rustc-main").path("compiler")
+        let crates = run.builder.in_tree_crates("rustc-main", None);
+        run.crates(crates).path("compiler")
     }
 
     fn make_run(run: RunConfig<'_>) {
-        run.builder.ensure(Rustc { target: run.target });
+        let crates = run.cargo_crates_in_set();
+        run.builder.ensure(Rustc { target: run.target, crates });
     }
 
     /// Builds the compiler.
@@ -200,7 +240,7 @@ impl Step for Rustc {
             builder.ensure(crate::compile::Std::new(compiler, compiler.host));
             builder.ensure(crate::compile::Std::new(compiler, target));
         } else {
-            builder.ensure(Std { target });
+            builder.ensure(Std::new(target));
         }
 
         let mut cargo = builder.cargo(
@@ -218,14 +258,17 @@ impl Step for Rustc {
             cargo.arg("--all-targets");
         }
 
-        // Explicitly pass -p for all compiler krates -- this will force cargo
+        // Explicitly pass -p for all compiler crates -- this will force cargo
         // to also check the tests/benches/examples for these crates, rather
         // than just the leaf crate.
-        for krate in builder.in_tree_crates("rustc-main", Some(target)) {
-            cargo.arg("-p").arg(krate.name);
+        for krate in &*self.crates {
+            cargo.arg("-p").arg(krate);
         }
 
-        let _guard = builder.msg_check("compiler artifacts", target);
+        let _guard = builder.msg_check(
+            format_args!("compiler artifacts{}", crate_description(&self.crates)),
+            target,
+        );
         run_cargo(
             builder,
             cargo,
@@ -268,7 +311,7 @@ impl Step for CodegenBackend {
         let target = self.target;
         let backend = self.backend;
 
-        builder.ensure(Rustc { target });
+        builder.ensure(Rustc::new(target, builder));
 
         let mut cargo = builder.cargo(
             compiler,
@@ -318,7 +361,7 @@ impl Step for RustAnalyzer {
         let compiler = builder.compiler(builder.top_stage, builder.config.build);
         let target = self.target;
 
-        builder.ensure(Std { target });
+        builder.ensure(Std::new(target));
 
         let mut cargo = prepare_tool_cargo(
             builder,
@@ -386,7 +429,7 @@ macro_rules! tool_check_step {
                 let compiler = builder.compiler(builder.top_stage, builder.config.build);
                 let target = self.target;
 
-                builder.ensure(Rustc { target });
+                builder.ensure(Rustc::new(target, builder));
 
                 let mut cargo = prepare_tool_cargo(
                     builder,