Unrolled build for rust-lang#139660

Rollup merge of rust-lang#139660 - Zalathar:new-executor, r=jieyouxu

compiletest: Add an experimental new executor to replace libtest

This PR adds a new "executor" to compiletest for running the list of collected tests, to eventually replace the current dependency on unstable libtest internals.

The new executor is currently inactive by default. It must be activated explicitly by passing `-n` or `--new-executor` to compiletest, e.g. `./x test ui -- -n`.

(After some amount of wider manual testing, the new executor will hopefully be made the default, and the libtest dependency can be removed. Contributors should not notice any change.)

The new executor is a stripped-down rewrite of the subset of libtest needed by compiletest.

# Supported functionality
- Specifying the number of concurrent tests with `RUST_TEST_THREADS`
- Filtering and skipping tests by name (substring or exact-match)
- Forcibly running ignored tests with `--ignored`
- Optional fail-fast with `--fail-fast`
- JSON output, compatible with bootstrap's parser for libtest output
- Running each test in its own thread
- Short backtraces that ignore the executor itself
- Slow test detection, with a hard-coded timeout of 60 seconds
- Capturing stdout/stderr, via `#![feature(internal_output_capture)]`
- Suppressing output capture with `--no-capture`

# Unsupported functionality
- Non-JSON output, as this is handled by bootstrap instead
- Separate code path for concurrency=1, as the concurrent path should handle this case naturally
- Fallback to running tests synchronously if new threads can't be spawned
- Special handling of hosts that don't support basic functionality like threads or timers
  - Our ability to test *targets* should be unaffected
- Graceful handling of some edge cases that could occur in arbitrary user-written unit tests, but would represent bugs in compiletest
- Due to the current need for output capture, the new executor is still not entirely written in stable Rust

---
r? jieyouxu

Author: rust-timer

src/bootstrap/src/core/build_steps/check.rs

@@ -3,7 +3,7 @@
 use crate::core::build_steps::compile::{
     add_to_sysroot, run_cargo, rustc_cargo, rustc_cargo_env, std_cargo, std_crates_for_run_make,
 };
-use crate::core::build_steps::tool::{SourceType, prepare_tool_cargo};
+use crate::core::build_steps::tool::{COMPILETEST_ALLOW_FEATURES, SourceType, prepare_tool_cargo};
 use crate::core::builder::{
     self, Alias, Builder, Kind, RunConfig, ShouldRun, Step, crate_description,
 };
@@ -416,7 +416,7 @@ impl Step for Compiletest {
             &[],
         );
 
-        cargo.allow_features("test");
+        cargo.allow_features(COMPILETEST_ALLOW_FEATURES);
 
         // For ./x.py clippy, don't run with --all-targets because
         // linting tests and benchmarks can produce very noisy results

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

@@ -15,7 +15,7 @@ use crate::core::build_steps::doc::DocumentationFormat;
 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::synthetic_targets::MirOptPanicAbortSyntheticTarget;
-use crate::core::build_steps::tool::{self, SourceType, Tool};
+use crate::core::build_steps::tool::{self, COMPILETEST_ALLOW_FEATURES, SourceType, Tool};
 use crate::core::build_steps::toolstate::ToolState;
 use crate::core::build_steps::{compile, dist, llvm};
 use crate::core::builder::{
@@ -721,7 +721,7 @@ impl Step for CompiletestTest {
             SourceType::InTree,
             &[],
         );
-        cargo.allow_features("test");
+        cargo.allow_features(COMPILETEST_ALLOW_FEATURES);
         run_cargo_test(cargo, &[], &[], "compiletest self test", host, builder);
     }
 }

src/bootstrap/src/core/build_steps/tool.rs

@@ -444,7 +444,11 @@ macro_rules! bootstrap_tool {
                         SourceType::InTree
                     },
                     extra_features: vec![],
-                    allow_features: concat!($($allow_features)*),
+                    allow_features: {
+                        let mut _value = "";
+                        $( _value = $allow_features; )?
+                        _value
+                    },
                     cargo_args: vec![],
                     artifact_kind: if false $(|| $artifact_kind == ToolArtifactKind::Library)* {
                         ToolArtifactKind::Library
@@ -458,6 +462,8 @@ macro_rules! bootstrap_tool {
     }
 }
 
+pub(crate) const COMPILETEST_ALLOW_FEATURES: &str = "test,internal_output_capture";
+
 bootstrap_tool!(
     // This is marked as an external tool because it includes dependencies
     // from submodules. Trying to keep the lints in sync between all the repos
@@ -468,7 +474,7 @@ bootstrap_tool!(
     Tidy, "src/tools/tidy", "tidy";
     Linkchecker, "src/tools/linkchecker", "linkchecker";
     CargoTest, "src/tools/cargotest", "cargotest";
-    Compiletest, "src/tools/compiletest", "compiletest", is_unstable_tool = true, allow_features = "test";
+    Compiletest, "src/tools/compiletest", "compiletest", is_unstable_tool = true, allow_features = COMPILETEST_ALLOW_FEATURES;
     BuildManifest, "src/tools/build-manifest", "build-manifest";
     RemoteTestClient, "src/tools/remote-test-client", "remote-test-client";
     RustInstaller, "src/tools/rust-installer", "rust-installer";
@@ -483,7 +489,8 @@ bootstrap_tool!(
     GenerateCopyright, "src/tools/generate-copyright", "generate-copyright";
     SuggestTests, "src/tools/suggest-tests", "suggest-tests";
     GenerateWindowsSys, "src/tools/generate-windows-sys", "generate-windows-sys";
-    RustdocGUITest, "src/tools/rustdoc-gui-test", "rustdoc-gui-test", is_unstable_tool = true, allow_features = "test";
+    // rustdoc-gui-test has a crate dependency on compiletest, so it needs the same unstable features.
+    RustdocGUITest, "src/tools/rustdoc-gui-test", "rustdoc-gui-test", is_unstable_tool = true, allow_features = COMPILETEST_ALLOW_FEATURES;
     CoverageDump, "src/tools/coverage-dump", "coverage-dump";
     WasmComponentLd, "src/tools/wasm-component-ld", "wasm-component-ld", is_unstable_tool = true, allow_features = "min_specialization";
     UnicodeTableGenerator, "src/tools/unicode-table-generator", "unicode-table-generator";

src/tools/compiletest/src/common.rs

@@ -414,6 +414,11 @@ pub struct Config {
     /// cross-compilation scenarios that do not otherwise want/need to `-Zbuild-std`. Used in e.g.
     /// ABI tests.
     pub minicore_path: Utf8PathBuf,
+
+    /// If true, run tests with the "new" executor that was written to replace
+    /// compiletest's dependency on libtest. Eventually this will become the
+    /// default, and the libtest dependency will be removed.
+    pub new_executor: bool,
 }
 
 impl Config {