Test that -Zbuild-std=core works on a variety of profiles

Cargo.lock

@@ -3334,6 +3334,7 @@ dependencies = [
  "rustdoc-json-types",
  "serde_json",
  "similar",
+ "tempfile",
  "wasmparser 0.236.1",
 ]
 

compiler/rustc_target/src/spec/targets/i586_unknown_redox.rs

@@ -11,7 +11,7 @@ pub(crate) fn target() -> Target {
 
     Target {
         llvm_target: "i586-unknown-redox".into(),
-        metadata: TargetMetadata { description: None, tier: None, host_tools: None, std: None },
+        metadata: TargetMetadata { description: None, tier: Some(3), host_tools: None, std: None },
         pointer_width: 32,
         data_layout:
             "e-m:e-p:32:32-p270:32:32-p271:32:32-p272:64:64-i128:128-f64:32:64-f80:32-n8:16:32-S128"

compiler/rustc_target/src/spec/targets/x86_64_unknown_linux_none.rs

@@ -15,7 +15,7 @@ pub(crate) fn target() -> Target {
         llvm_target: "x86_64-unknown-linux-none".into(),
         metadata: TargetMetadata {
             description: None,
-            tier: None,
+            tier: Some(3),
             host_tools: None,
             std: Some(false),
         },

compiler/rustc_target/src/spec/targets/xtensa_esp32_espidf.rs

@@ -9,7 +9,7 @@ pub(crate) fn target() -> Target {
         pointer_width: 32,
         data_layout: "e-m:e-p:32:32-v1:8:8-i64:64-i128:128-n32".into(),
         arch: Arch::Xtensa,
-        metadata: TargetMetadata { description: None, tier: None, host_tools: None, std: None },
+        metadata: TargetMetadata { description: None, tier: Some(3), host_tools: None, std: None },
 
         options: TargetOptions {
             endian: Endian::Little,

compiler/rustc_target/src/spec/targets/xtensa_esp32s2_espidf.rs

@@ -9,7 +9,7 @@ pub(crate) fn target() -> Target {
         pointer_width: 32,
         data_layout: "e-m:e-p:32:32-v1:8:8-i64:64-i128:128-n32".into(),
         arch: Arch::Xtensa,
-        metadata: TargetMetadata { description: None, tier: None, host_tools: None, std: None },
+        metadata: TargetMetadata { description: None, tier: Some(3), host_tools: None, std: None },
 
         options: TargetOptions {
             endian: Endian::Little,

compiler/rustc_target/src/spec/targets/xtensa_esp32s3_espidf.rs

@@ -9,7 +9,7 @@ pub(crate) fn target() -> Target {
         pointer_width: 32,
         data_layout: "e-m:e-p:32:32-v1:8:8-i64:64-i128:128-n32".into(),
         arch: Arch::Xtensa,
-        metadata: TargetMetadata { description: None, tier: None, host_tools: None, std: None },
+        metadata: TargetMetadata { description: None, tier: Some(3), host_tools: None, std: None },
 
         options: TargetOptions {
             endian: Endian::Little,

src/bootstrap/mk/Makefile.in

@@ -53,6 +53,11 @@ check-aux:
 		src/tools/cargotest \
 		src/tools/test-float-parse \
 		$(BOOTSTRAP_ARGS)
+	# The build-std suite is off by default because it is uncommonly slow
+	# and memory-hungry.
+	$(Q)$(BOOTSTRAP) test --stage 2 \
+		build-std \
+		$(BOOTSTRAP_ARGS)
 	# Run standard library tests in Miri.
 	$(Q)MIRIFLAGS="-Zmiri-strict-provenance" \
 		$(BOOTSTRAP) miri --stage 2 \

src/bootstrap/src/core/build_steps/test.rs

@@ -1625,6 +1625,12 @@ test!(RunMakeCargo {
     suite: "run-make-cargo",
     default: true
 });
+test!(BuildStd {
+    path: "tests/build-std",
+    mode: CompiletestMode::RunMake,
+    suite: "build-std",
+    default: false
+});
 
 test!(AssemblyLlvm {
     path: "tests/assembly-llvm",
@@ -1948,7 +1954,7 @@ NOTE: if you're sure you want to do this, please open an issue as to why. In the
             let stage0_rustc_path = builder.compiler(0, test_compiler.host);
             cmd.arg("--stage0-rustc-path").arg(builder.rustc(stage0_rustc_path));
 
-            if suite == "run-make-cargo" {
+            if matches!(suite, "run-make-cargo" | "build-std") {
                 let cargo_path = if test_compiler.stage == 0 {
                     // If we're using `--stage 0`, we should provide the bootstrap cargo.
                     builder.initial_cargo.clone()

src/bootstrap/src/core/builder/cli_paths.rs

@@ -20,6 +20,7 @@ pub(crate) const PATH_REMAP: &[(&str, &[&str])] = &[
         &[
             // tidy-alphabetical-start
             "tests/assembly-llvm",
+            "tests/build-std",
             "tests/codegen-llvm",
             "tests/codegen-units",
             "tests/coverage",

src/bootstrap/src/core/builder/cli_paths/snapshots/x_test_tests.snap

@@ -5,6 +5,9 @@ expression: test tests
 [Test] test::AssemblyLlvm
     targets: [aarch64-unknown-linux-gnu]
     - Suite(test::tests/assembly-llvm)
+[Test] test::BuildStd
+    targets: [aarch64-unknown-linux-gnu]
+    - Suite(test::tests/build-std)
 [Test] test::CodegenLlvm
     targets: [aarch64-unknown-linux-gnu]
     - Suite(test::tests/codegen-llvm)

src/bootstrap/src/core/builder/cli_paths/snapshots/x_test_tests_skip_coverage.snap

@@ -5,6 +5,9 @@ expression: test tests --skip=coverage
 [Test] test::AssemblyLlvm
     targets: [aarch64-unknown-linux-gnu]
     - Suite(test::tests/assembly-llvm)
+[Test] test::BuildStd
+    targets: [aarch64-unknown-linux-gnu]
+    - Suite(test::tests/build-std)
 [Test] test::CodegenLlvm
     targets: [aarch64-unknown-linux-gnu]
     - Suite(test::tests/codegen-llvm)

src/bootstrap/src/core/builder/mod.rs

@@ -927,6 +927,7 @@ impl<'a> Builder<'a> {
                 test::CollectLicenseMetadata,
                 test::RunMake,
                 test::RunMakeCargo,
+                test::BuildStd,
             ),
             Kind::Miri => describe!(test::Crate),
             Kind::Bench => describe!(test::Crate, test::CrateLibrustc, test::CrateRustdoc),

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

@@ -2077,7 +2077,7 @@ mod snapshot {
         let ctx = TestCtx::new();
         insta::assert_snapshot!(
             prepare_test_config(&ctx)
-                .render_steps(), @r"
+                .render_steps(), @"
         [build] rustc 0 <host> -> Tidy 1 <host>
         [test] tidy <>
         [build] rustdoc 0 <host>
@@ -2255,7 +2255,7 @@ mod snapshot {
         insta::assert_snapshot!(
             prepare_test_config(&ctx)
                 .stage(2)
-                .render_steps(), @r"
+                .render_steps(), @"
         [build] rustc 0 <host> -> Tidy 1 <host>
         [test] tidy <>
         [build] rustdoc 0 <host>

src/doc/rustc-dev-guide/src/tests/compiletest.md

@@ -78,6 +78,10 @@ The following test suites are available, with links for more information:
 
 [`run-make`](#run-make-tests) are general purpose tests using Rust programs.
 
+### The build-std test suite
+
+[`build-std`](#build-std-tests) test that -Zbuild-std works.
+
 ### Rustdoc test suites
 
 | Test suite                           | Purpose                                                                  |
@@ -429,6 +433,12 @@ use cases that require testing in-tree `cargo` in conjunction with in-tree `rust
 The `run-make` test suite does not have access to in-tree `cargo` (so it can be the
 faster-to-iterate test suite).
 
+### `build-std` tests
+
+The tests in [`tests/build-std`] check that `-Zbuild-std` works. This is currently
+just a run-make test suite with a single recipe. The recipe generates test cases
+and runs them in parallel.
+
 #### Using Rust recipes
 
 Each test should be in a separate directory with a `rmake.rs` Rust program,

src/tools/compiletest/src/common.rs

@@ -77,6 +77,7 @@ string_enum! {
         RustdocUi => "rustdoc-ui",
         Ui => "ui",
         UiFullDeps => "ui-fulldeps",
+        BuildStd => "build-std",
     }
 }
 

src/tools/compiletest/src/runtest/run_make.rs

@@ -190,8 +190,8 @@ impl TestCx<'_> {
             // through a specific CI runner).
             .env("LLVM_COMPONENTS", &self.config.llvm_components);
 
-        // Only `run-make-cargo` test suite gets an in-tree `cargo`, not `run-make`.
-        if self.config.suite == TestSuite::RunMakeCargo {
+        // The `run-make-cargo` and `build-std` suites need an in-tree `cargo`, `run-make` does not.
+        if matches!(self.config.suite, TestSuite::RunMakeCargo | TestSuite::BuildStd) {
             cmd.env(
                 "CARGO",
                 self.config.cargo_path.as_ref().expect("cargo must be built and made available"),

src/tools/run-make-support/Cargo.toml

@@ -17,6 +17,7 @@ object = "0.37"
 regex = "1.11"
 serde_json = "1.0"
 similar = "2.7"
+tempfile = "3"
 wasmparser = { version = "0.236", default-features = false, features = ["std", "features", "validate"] }
 # tidy-alphabetical-end
 

src/tools/run-make-support/src/command.rs

@@ -46,6 +46,8 @@ pub struct Command {
     // Emulate linear type semantics.
     drop_bomb: DropBomb,
     already_executed: bool,
+
+    context: String,
 }
 
 impl Command {
@@ -60,6 +62,7 @@ impl Command {
             stdout: None,
             stderr: None,
             already_executed: false,
+            context: String::new(),
         }
     }
 
@@ -69,6 +72,16 @@ impl Command {
         self.cmd
     }
 
+    pub(crate) fn get_context(&self) -> &str {
+        &self.context
+    }
+
+    /// Appends context to the command, to provide a better error message if the command fails.
+    pub fn context(&mut self, ctx: &str) -> &mut Self {
+        self.context.push_str(&format!("{ctx}\n"));
+        self
+    }
+
     /// Specify a stdin input buffer. This is a convenience helper,
     pub fn stdin_buf<I: AsRef<[u8]>>(&mut self, input: I) -> &mut Self {
         self.stdin_buf = Some(input.as_ref().to_vec().into_boxed_slice());

src/tools/run-make-support/src/lib.rs

@@ -34,7 +34,9 @@ pub mod rfs {
 }
 
 // Re-exports of third-party library crates.
-pub use {bstr, gimli, libc, object, regex, rustdoc_json_types, serde_json, similar, wasmparser};
+pub use {
+    bstr, gimli, libc, object, regex, rustdoc_json_types, serde_json, similar, tempfile, wasmparser,
+};
 
 // Helpers for building names of output artifacts that are potentially target-specific.
 pub use crate::artifact_names::{

src/tools/run-make-support/src/util.rs

@@ -21,6 +21,9 @@ pub(crate) fn handle_failed_output(
     eprintln!("output status: `{}`", output.status());
     eprintln!("=== STDOUT ===\n{}\n\n", output.stdout_utf8());
     eprintln!("=== STDERR ===\n{}\n\n", output.stderr_utf8());
+    if !cmd.get_context().is_empty() {
+        eprintln!("Context:\n{}", cmd.get_context());
+    }
     std::process::exit(1)
 }
 

tests/build-std/configurations/rmake.rs

@@ -0,0 +1,131 @@
+// This test ensures we are able to compile -Zbuild-std=core under a variety of profiles.
+// Currently, it tests that we can compile to all Tier 1 targets, and it does this by checking what
+// the tier metadata in target-spec JSON. This means that all in-tree targets must have a tier set.
+
+#![deny(warnings)]
+
+use std::collections::HashMap;
+use std::sync::{Arc, Mutex};
+use std::thread;
+
+use run_make_support::serde_json::{self, Value};
+use run_make_support::tempfile::TempDir;
+use run_make_support::{cargo, rfs, rustc};
+
+#[derive(Clone)]
+struct Task {
+    target: String,
+    opt_level: u8,
+    debug: u8,
+    panic: &'static str,
+}
+
+fn manifest(task: &Task) -> String {
+    let Task { opt_level, debug, panic, target: _ } = task;
+    format!(
+        r#"[package]
+name = "scratch"
+version = "0.1.0"
+edition = "2024"
+
+[lib]
+path = "lib.rs"
+
+[profile.release]
+opt-level = {opt_level}
+debug = {debug}
+panic = "{panic}"
+"#
+    )
+}
+
+fn main() {
+    let mut targets = Vec::new();
+    let all_targets =
+        rustc().args(&["--print=all-target-specs-json", "-Zunstable-options"]).run().stdout_utf8();
+    let all_targets: HashMap<String, Value> = serde_json::from_str(&all_targets).unwrap();
+    for (target, spec) in all_targets {
+        let metadata = spec.as_object().unwrap()["metadata"].as_object().unwrap();
+        let tier = metadata["tier"]
+            .as_u64()
+            .expect(&format!("Target {} is missing tier metadata", target));
+        if tier == 1 {
+            targets.push(target);
+        }
+    }
+
+    let mut tasks = Vec::new();
+
+    // Testing every combination of compiler flags is infeasible. So we are making some attempt to
+    // choose combinations that will tend to run into problems.
+    //
+    // The particular combination of settings below is tuned to look for problems generating the
+    // code for compiler-builtins.
+    // We only exercise opt-level 0 and 3 to exercise mir-opt-level 1 and 2.
+    // We only exercise debug 0 and 2 because level 2 turns off some MIR optimizations.
+    // We only test abort and immediate-abort because abort vs unwind doesn't change MIR much at
+    // all. but immediate-abort does.
+    //
+    // Currently this only tests that we can compile the tier 1 targets. But since we are using
+    // -Zbuild-std=core, we could have any list of targets.
+
+    for opt_level in [0, 3] {
+        for debug in [0, 2] {
+            for panic in ["abort", "immediate-abort"] {
+                for target in &targets {
+                    tasks.push(Task { target: target.clone(), opt_level, debug, panic });
+                }
+            }
+        }
+    }
+
+    let tasks = Arc::new(Mutex::new(tasks));
+    let mut threads = Vec::new();
+
+    // Try to obey the -j argument passed to bootstrap, otherwise fall back to using all the system
+    // resouces. This test can be rather memory-hungry (~1 GB/thread); if it causes trouble in
+    // practice do not hesitate to limit its parallelism.
+    for _ in 0..run_make_support::env::jobs() {
+        let tasks = Arc::clone(&tasks);
+        let handle = thread::spawn(move || {
+            loop {
+                let maybe_task = tasks.lock().unwrap().pop();
+                if let Some(task) = maybe_task {
+                    test(task);
+                } else {
+                    break;
+                }
+            }
+        });
+        threads.push(handle);
+    }
+
+    for t in threads {
+        t.join().unwrap();
+    }
+}
+
+fn test(task: Task) {
+    let dir = TempDir::new().unwrap();
+
+    let manifest = manifest(&task);
+    rfs::write(dir.path().join("Cargo.toml"), &manifest);
+    rfs::write(dir.path().join("lib.rs"), "#![no_std]");
+
+    let mut args = vec!["build", "--release", "-Zbuild-std=core", "--target", &task.target, "-j1"];
+    if task.panic == "immediate-abort" {
+        args.push("-Zpanic-immediate-abort");
+    }
+    cargo()
+        .current_dir(dir.path())
+        .args(&args)
+        .env("RUSTC_BOOTSTRAP", "1")
+        // Visual Studio 2022 requires that the LIB env var be set so it can
+        // find the Windows SDK.
+        .env("LIB", std::env::var("LIB").unwrap_or_default())
+        .context(&format!(
+            "build-std for target `{}` failed with the following Cargo.toml:\n\n{manifest}",
+            task.target
+        ))
+        .run();
+}