Add bootstrap option to compile a tool with features

bootstrap.example.toml

@@ -381,6 +381,14 @@
 #    "miri", "cargo-miri" # for dev/nightly channels
 #]
 
+# Specify build configuration specific for some tool, such as enabled features.
+#
+# For example, to build Miri with tracing support, use `tool-config.miri.features = ["tracing"]`
+#
+# The default value for the `features` array is `[]`. However, please note that other flags in
+# `bootstrap.toml` might influence the features enabled for some tools.
+#tool-config.TOOL_NAME.features = [FEATURE1, FEATURE2]
+
 # Verbosity level: 0 == not verbose, 1 == verbose, 2 == very verbose, 3 == print environment variables on each rustc invocation
 #verbose = 0
 

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

@@ -136,6 +136,20 @@ fn run(mut self, builder: &Builder<'_>) -> ToolBuildResult {
             _ => panic!("unexpected Mode for tool build"),
         }
 
+        // build.tool-config.TOOL_NAME.features in bootstrap.toml allows specifying which features
+        // to enable for a specific tool. `extra_features` instead is not controlled by the toml
+        // instead provides features that are always enabled for a specific tool (e.g.
+        // "in-rust-tree" for rust-analyzer). Finally, `prepare_tool_cargo` might add more features
+        // to adapt the build to the chosen flags (e.g. "all-static" for cargo if
+        // `cargo_native_static` is true).
+        let mut features = builder
+            .config
+            .tool_config
+            .get(self.tool)
+            .and_then(|tool_config| tool_config.features.clone())
+            .unwrap_or_default();
+        features.extend(self.extra_features.clone());
+
         let mut cargo = prepare_tool_cargo(
             builder,
             self.compiler,
@@ -144,7 +158,7 @@ fn run(mut self, builder: &Builder<'_>) -> ToolBuildResult {
             Kind::Build,
             path,
             self.source_type,
-            &self.extra_features,
+            &features,
         );
 
         // The stage0 compiler changes infrequently and does not directly depend on code

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

@@ -35,7 +35,7 @@
 use crate::core::config::flags::{Color, Flags};
 use crate::core::config::target_selection::TargetSelectionList;
 use crate::core::config::toml::TomlConfig;
-use crate::core::config::toml::build::Build;
+use crate::core::config::toml::build::{Build, ToolConfig};
 use crate::core::config::toml::change_id::ChangeId;
 use crate::core::config::toml::rust::{
     LldMode, RustOptimize, check_incompatible_options_for_ci_rustc,
@@ -114,6 +114,7 @@ pub struct Config {
     pub bootstrap_cache_path: Option<PathBuf>,
     pub extended: bool,
     pub tools: Option<HashSet<String>>,
+    pub tool_config: HashMap<String, ToolConfig>,
     pub sanitizers: bool,
     pub profiler: bool,
     pub omit_git_hash: bool,
@@ -689,6 +690,7 @@ fn get_table(option: &str) -> Result<TomlConfig, toml::de::Error> {
             bootstrap_cache_path,
             extended,
             tools,
+            tool_config,
             verbose,
             sanitizers,
             profiler,
@@ -835,6 +837,7 @@ fn get_table(option: &str) -> Result<TomlConfig, toml::de::Error> {
         set(&mut config.full_bootstrap, full_bootstrap);
         set(&mut config.extended, extended);
         config.tools = tools;
+        set(&mut config.tool_config, tool_config);
         set(&mut config.verbose, verbose);
         set(&mut config.sanitizers, sanitizers);
         set(&mut config.profiler, profiler);

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

@@ -6,6 +6,8 @@
 //! various feature flags. These options apply across different stages and components
 //! unless specifically overridden by other configuration sections or command-line flags.
 
+use std::collections::HashMap;
+
 use serde::{Deserialize, Deserializer};
 
 use crate::core::config::toml::ReplaceOpt;
@@ -42,6 +44,7 @@ struct Build {
         bootstrap_cache_path: Option<PathBuf> = "bootstrap-cache-path",
         extended: Option<bool> = "extended",
         tools: Option<HashSet<String>> = "tools",
+        tool_config: Option<HashMap<String, ToolConfig>> = "tool-config",
         verbose: Option<usize> = "verbose",
         sanitizers: Option<bool> = "sanitizers",
         profiler: Option<bool> = "profiler",
@@ -70,3 +73,10 @@ struct Build {
         exclude: Option<Vec<PathBuf>> = "exclude",
     }
 }
+
+define_config! {
+    #[derive(Default, Clone)]
+    struct ToolConfig {
+        features: Option<Vec<String>> = "features",
+    }
+}

src/bootstrap/src/utils/change_tracker.rs

@@ -421,4 +421,9 @@ pub fn human_readable_changes(changes: &[ChangeInfo]) -> String {
         severity: ChangeSeverity::Info,
         summary: "Added new bootstrap flag `--skip-std-check-if-no-download-rustc` that skips std checks when download-rustc is unavailable. Mainly intended for developers to reduce RA overhead.",
     },
+    ChangeInfo {
+        change_id: 142379,
+        severity: ChangeSeverity::Info,
+        summary: "Added new option `tool-config.TOOL_NAME.features` to specify the features to compile a tool with",
+    },
 ];