Remove ability to check/build/test compiletest as stage 0 bootstrap tool

Instead, consider this as an `ToolStd` tool until `compiletest`'s
dependency in the unstable `#![feature(internal_output_capture)]` is
replaced by a stable implementation.

Author: jieyouxu

bootstrap.example.toml

@@ -465,9 +465,6 @@
 # What custom diff tool to use for displaying compiletest tests.
 #build.compiletest-diff-tool = <none>
 
-# Whether to use the precompiled stage0 libtest with compiletest.
-#build.compiletest-use-stage0-libtest = true
-
 # Default value for the `--extra-checks` flag of tidy.
 #
 # See `./x test tidy --help` for details.

src/bootstrap/defaults/bootstrap.dist.toml

@@ -7,8 +7,6 @@ test-stage = 2
 doc-stage = 2
 # When compiling from source, you usually want all tools.
 extended = true
-# Use libtest built from the source tree instead of the precompiled one from stage 0.
-compiletest-use-stage0-libtest = false
 
 # Most users installing from source want to build all parts of the project from source.
 [llvm]

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

@@ -376,7 +376,7 @@ macro_rules! tool_check_step {
             // The part of this path after the final '/' is also used as a display name.
             path: $path:literal
             $(, alt_path: $alt_path:literal )*
-            // Closure that returns `Mode` based on the passed `&Builder<'_>`
+            // Under which tool mode should the tool be checked with?
             , mode: $mode:expr
             // Subset of nightly features that are allowed to be used when checking
             $(, allow_features: $allow_features:expr )?
@@ -404,8 +404,7 @@ macro_rules! tool_check_step {
 
             fn make_run(run: RunConfig<'_>) {
                 let target = run.target;
-                let builder = run.builder;
-                let mode = $mode(builder);
+                let mode = $mode;
 
                 let build_compiler = prepare_compiler_for_check(run.builder, target, mode);
 
@@ -426,7 +425,7 @@ macro_rules! tool_check_step {
                     _value
                 };
                 let extra_features: &[&str] = &[$($($enable_features),*)?];
-                let mode = $mode(builder);
+                let mode = $mode;
                 run_tool_check_step(builder, build_compiler, target, $path, mode, allow_features, extra_features);
             }
 
@@ -493,66 +492,61 @@ fn run_tool_check_step(
 tool_check_step!(Rustdoc {
     path: "src/tools/rustdoc",
     alt_path: "src/librustdoc",
-    mode: |_builder| Mode::ToolRustc
+    mode: Mode::ToolRustc
 });
 // Clippy, miri and Rustfmt are hybrids. They are external tools, but use a git subtree instead
 // of a submodule. Since the SourceType only drives the deny-warnings
 // behavior, treat it as in-tree so that any new warnings in clippy will be
 // rejected.
-tool_check_step!(Clippy { path: "src/tools/clippy", mode: |_builder| Mode::ToolRustc });
-tool_check_step!(Miri { path: "src/tools/miri", mode: |_builder| Mode::ToolRustc });
-tool_check_step!(CargoMiri { path: "src/tools/miri/cargo-miri", mode: |_builder| Mode::ToolRustc });
-tool_check_step!(Rustfmt { path: "src/tools/rustfmt", mode: |_builder| Mode::ToolRustc });
+tool_check_step!(Clippy { path: "src/tools/clippy", mode: Mode::ToolRustc });
+tool_check_step!(Miri { path: "src/tools/miri", mode: Mode::ToolRustc });
+tool_check_step!(CargoMiri { path: "src/tools/miri/cargo-miri", mode: Mode::ToolRustc });
+tool_check_step!(Rustfmt { path: "src/tools/rustfmt", mode: Mode::ToolRustc });
 tool_check_step!(RustAnalyzer {
     path: "src/tools/rust-analyzer",
-    mode: |_builder| Mode::ToolRustc,
+    mode: Mode::ToolRustc,
     allow_features: tool::RustAnalyzer::ALLOW_FEATURES,
     enable_features: ["in-rust-tree"],
 });
 tool_check_step!(MiroptTestTools {
     path: "src/tools/miropt-test-tools",
-    mode: |_builder| Mode::ToolBootstrap
+    mode: Mode::ToolBootstrap
 });
 // We want to test the local std
 tool_check_step!(TestFloatParse {
     path: "src/tools/test-float-parse",
-    mode: |_builder| Mode::ToolStd,
+    mode: Mode::ToolStd,
     allow_features: tool::TestFloatParse::ALLOW_FEATURES
 });
 tool_check_step!(FeaturesStatusDump {
     path: "src/tools/features-status-dump",
-    mode: |_builder| Mode::ToolBootstrap
+    mode: Mode::ToolBootstrap
 });
 
-tool_check_step!(Bootstrap {
-    path: "src/bootstrap",
-    mode: |_builder| Mode::ToolBootstrap,
-    default: false
-});
+tool_check_step!(Bootstrap { path: "src/bootstrap", mode: Mode::ToolBootstrap, default: false });
 
 // `run-make-support` will be built as part of suitable run-make compiletest test steps, but support
 // check to make it easier to work on.
 tool_check_step!(RunMakeSupport {
     path: "src/tools/run-make-support",
-    mode: |_builder| Mode::ToolBootstrap,
+    mode: Mode::ToolBootstrap,
     default: false
 });
 
 tool_check_step!(CoverageDump {
     path: "src/tools/coverage-dump",
-    mode: |_builder| Mode::ToolBootstrap,
+    mode: Mode::ToolBootstrap,
     default: false
 });
 
 // Compiletest is implicitly "checked" when it gets built in order to run tests,
 // so this is mainly for people working on compiletest to run locally.
 tool_check_step!(Compiletest {
     path: "src/tools/compiletest",
-    mode: |builder: &Builder<'_>| if builder.config.compiletest_use_stage0_libtest {
-        Mode::ToolBootstrap
-    } else {
-        Mode::ToolStd
-    },
+    // Note: compiletest currently still depends on `#![feature(internal_output_capture)]`, so
+    // should be considered a `ToolStd` tool for robustness, as it is *possible* for that internal
+    // library feature to be changed.
+    mode: Mode::ToolStd,
     allow_features: COMPILETEST_ALLOW_FEATURES,
     default: false,
 });

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

@@ -491,13 +491,12 @@ macro_rules! bootstrap_tool {
                 )*
 
                 let is_unstable = false $(|| $unstable)*;
-                let compiletest_wants_stage0 = $tool_name == "compiletest" && builder.config.compiletest_use_stage0_libtest;
 
                 builder.ensure(ToolBuild {
                     build_compiler: self.compiler,
                     target: self.target,
                     tool: $tool_name,
-                    mode: if is_unstable && !compiletest_wants_stage0 {
+                    mode: if is_unstable {
                         // use in-tree libraries for unstable features
                         Mode::ToolStd
                     } else {

src/bootstrap/src/core/config/config.rs

@@ -296,8 +296,6 @@ pub struct Config {
     /// Command for visual diff display, e.g. `diff-tool --color=always`.
     pub compiletest_diff_tool: Option<String>,
 
-    /// Whether to use the precompiled stage0 libtest with compiletest.
-    pub compiletest_use_stage0_libtest: bool,
     /// Default value for `--extra-checks`
     pub tidy_extra_checks: Option<String>,
     pub is_running_on_ci: bool,
@@ -747,7 +745,6 @@ impl Config {
             optimized_compiler_builtins,
             jobs,
             compiletest_diff_tool,
-            compiletest_use_stage0_libtest,
             tidy_extra_checks,
             ccache,
             exclude,
@@ -1013,7 +1010,6 @@ impl Config {
         config.optimized_compiler_builtins =
             optimized_compiler_builtins.unwrap_or(config.channel != "dev");
         config.compiletest_diff_tool = compiletest_diff_tool;
-        config.compiletest_use_stage0_libtest = compiletest_use_stage0_libtest.unwrap_or(true);
         config.tidy_extra_checks = tidy_extra_checks;
 
         let download_rustc = config.download_rustc_commit.is_some();

src/bootstrap/src/core/config/toml/build.rs

@@ -68,7 +68,6 @@ define_config! {
         optimized_compiler_builtins: Option<bool> = "optimized-compiler-builtins",
         jobs: Option<u32> = "jobs",
         compiletest_diff_tool: Option<String> = "compiletest-diff-tool",
-        compiletest_use_stage0_libtest: Option<bool> = "compiletest-use-stage0-libtest",
         tidy_extra_checks: Option<String> = "tidy-extra-checks",
         ccache: Option<StringOrBool> = "ccache",
         exclude: Option<Vec<PathBuf>> = "exclude",

src/bootstrap/src/utils/change_tracker.rs

@@ -486,4 +486,9 @@ pub const CONFIG_CHANGE_HISTORY: &[ChangeInfo] = &[
         severity: ChangeSeverity::Warning,
         summary: "Removed `rust.description` and `llvm.ccache` as it was deprecated in #137723 and #136941 long time ago.",
     },
+    ChangeInfo {
+        change_id: 999999,
+        severity: ChangeSeverity::Warning,
+        summary: "Removed `build.compiletest-use-stage0-libtest` as `compiletest` no longer uses libtest executor",
+    },
 ];