src/bootstrap/config.rs

   1 //! Serialized configuration of a build.
   2 //!
   3 //! This module implements parsing `config.toml` configuration files to tweak
   4 //! how the build runs.
   5
   6 use std::cell::{Cell, RefCell};
   7 use std::cmp;
   8 use std::collections::{HashMap, HashSet};
   9 use std::env;
  10 use std::ffi::OsStr;
  11 use std::fmt;
  12 use std::fs;
  13 use std::path::{Path, PathBuf};
  14 use std::process::Command;
  15 use std::str::FromStr;
  16
  17 use crate::builder::{Builder, TaskPath};
  18 use crate::cache::{Interned, INTERNER};
  19 use crate::channel::GitInfo;
  20 pub use crate::flags::Subcommand;
  21 use crate::flags::{Color, Flags};
  22 use crate::util::{exe, output, program_out_of_date, t};
  23 use once_cell::sync::OnceCell;
  24 use serde::{Deserialize, Deserializer};
  25
  26 macro_rules! check_ci_llvm {
  27     ($name:expr) => {
  28         assert!(
  29             $name.is_none(),
  30             "setting {} is incompatible with download-ci-llvm.",
  31             stringify!($name)
  32         );
  33     };
  34 }
  35
  36 /// Global configuration for the entire build and/or bootstrap.
  37 ///
  38 /// This structure is derived from a combination of both `config.toml` and
  39 /// `config.mk`. As of the time of this writing it's unlikely that `config.toml`
  40 /// is used all that much, so this is primarily filled out by `config.mk` which
  41 /// is generated from `./configure`.
  42 ///
  43 /// Note that this structure is not decoded directly into, but rather it is
  44 /// filled out from the decoded forms of the structs below. For documentation
  45 /// each field, see the corresponding fields in
  46 /// `config.toml.example`.
  47 #[derive(Default)]
  48 #[cfg_attr(test, derive(Clone))]
  49 pub struct Config {
  50     pub changelog_seen: Option<usize>,
  51     pub ccache: Option<String>,
  52     /// Call Build::ninja() instead of this.
  53     pub ninja_in_file: bool,
  54     pub verbose: usize,
  55     pub submodules: Option<bool>,
  56     pub compiler_docs: bool,
  57     pub docs_minification: bool,
  58     pub docs: bool,
  59     pub locked_deps: bool,
  60     pub vendor: bool,
  61     pub target_config: HashMap<TargetSelection, Target>,
  62     pub full_bootstrap: bool,
  63     pub extended: bool,
  64     pub tools: Option<HashSet<String>>,
  65     pub sanitizers: bool,
  66     pub profiler: bool,
  67     pub ignore_git: bool,
  68     pub exclude: Vec<TaskPath>,
  69     pub include_default_paths: bool,
  70     pub rustc_error_format: Option<String>,
  71     pub json_output: bool,
  72     pub test_compare_mode: bool,
  73     pub color: Color,
  74     pub patch_binaries_for_nix: bool,
  75     pub stage0_metadata: Stage0Metadata,
  76
  77     pub on_fail: Option<String>,
  78     pub stage: u32,
  79     pub keep_stage: Vec<u32>,
  80     pub keep_stage_std: Vec<u32>,
  81     pub src: PathBuf,
  82     /// defaults to `config.toml`
  83     pub config: PathBuf,
  84     pub jobs: Option<u32>,
  85     pub cmd: Subcommand,
  86     pub incremental: bool,
  87     pub dry_run: bool,
  88     /// `None` if we shouldn't download CI compiler artifacts, or the commit to download if we should.
  89     #[cfg(not(test))]
  90     download_rustc_commit: Option<String>,
  91     #[cfg(test)]
  92     pub download_rustc_commit: Option<String>,
  93
  94     pub deny_warnings: bool,
  95     pub backtrace_on_ice: bool,
  96
  97     // llvm codegen options
  98     pub llvm_skip_rebuild: bool,
  99     pub llvm_assertions: bool,
 100     pub llvm_tests: bool,
 101     pub llvm_plugins: bool,
 102     pub llvm_optimize: bool,
 103     pub llvm_thin_lto: bool,
 104     pub llvm_release_debuginfo: bool,
 105     pub llvm_version_check: bool,
 106     pub llvm_static_stdcpp: bool,
 107     /// `None` if `llvm_from_ci` is true and we haven't yet downloaded llvm.
 108     #[cfg(not(test))]
 109     llvm_link_shared: Cell<Option<bool>>,
 110     #[cfg(test)]
 111     pub llvm_link_shared: Cell<Option<bool>>,
 112     pub llvm_clang_cl: Option<String>,
 113     pub llvm_targets: Option<String>,
 114     pub llvm_experimental_targets: Option<String>,
 115     pub llvm_link_jobs: Option<u32>,
 116     pub llvm_version_suffix: Option<String>,
 117     pub llvm_use_linker: Option<String>,
 118     pub llvm_allow_old_toolchain: bool,
 119     pub llvm_polly: bool,
 120     pub llvm_clang: bool,
 121     pub llvm_from_ci: bool,
 122     pub llvm_build_config: HashMap<String, String>,
 123
 124     pub use_lld: bool,
 125     pub lld_enabled: bool,
 126     pub llvm_tools_enabled: bool,
 127
 128     pub llvm_cflags: Option<String>,
 129     pub llvm_cxxflags: Option<String>,
 130     pub llvm_ldflags: Option<String>,
 131     pub llvm_use_libcxx: bool,
 132
 133     // rust codegen options
 134     pub rust_optimize: bool,
 135     pub rust_codegen_units: Option<u32>,
 136     pub rust_codegen_units_std: Option<u32>,
 137     pub rust_debug_assertions: bool,
 138     pub rust_debug_assertions_std: bool,
 139     pub rust_overflow_checks: bool,
 140     pub rust_overflow_checks_std: bool,
 141     pub rust_debug_logging: bool,
 142     pub rust_debuginfo_level_rustc: u32,
 143     pub rust_debuginfo_level_std: u32,
 144     pub rust_debuginfo_level_tools: u32,
 145     pub rust_debuginfo_level_tests: u32,
 146     pub rust_split_debuginfo: SplitDebuginfo,
 147     pub rust_rpath: bool,
 148     pub rustc_parallel: bool,
 149     pub rustc_default_linker: Option<String>,
 150     pub rust_optimize_tests: bool,
 151     pub rust_dist_src: bool,
 152     pub rust_codegen_backends: Vec<Interned<String>>,
 153     pub rust_verify_llvm_ir: bool,
 154     pub rust_thin_lto_import_instr_limit: Option<u32>,
 155     pub rust_remap_debuginfo: bool,
 156     pub rust_new_symbol_mangling: Option<bool>,
 157     pub rust_profile_use: Option<String>,
 158     pub rust_profile_generate: Option<String>,
 159     pub rust_lto: RustcLto,
 160     pub llvm_profile_use: Option<String>,
 161     pub llvm_profile_generate: bool,
 162     pub llvm_libunwind_default: Option<LlvmLibunwind>,
 163     pub llvm_bolt_profile_generate: bool,
 164     pub llvm_bolt_profile_use: Option<String>,
 165
 166     pub build: TargetSelection,
 167     pub hosts: Vec<TargetSelection>,
 168     pub targets: Vec<TargetSelection>,
 169     pub local_rebuild: bool,
 170     pub jemalloc: bool,
 171     pub control_flow_guard: bool,
 172
 173     // dist misc
 174     pub dist_sign_folder: Option<PathBuf>,
 175     pub dist_upload_addr: Option<String>,
 176     pub dist_compression_formats: Option<Vec<String>>,
 177
 178     // libstd features
 179     pub backtrace: bool, // support for RUST_BACKTRACE
 180
 181     // misc
 182     pub low_priority: bool,
 183     pub channel: String,
 184     pub description: Option<String>,
 185     pub verbose_tests: bool,
 186     pub save_toolstates: Option<PathBuf>,
 187     pub print_step_timings: bool,
 188     pub print_step_rusage: bool,
 189     pub missing_tools: bool,
 190
 191     // Fallback musl-root for all targets
 192     pub musl_root: Option<PathBuf>,
 193     pub prefix: Option<PathBuf>,
 194     pub sysconfdir: Option<PathBuf>,
 195     pub datadir: Option<PathBuf>,
 196     pub docdir: Option<PathBuf>,
 197     pub bindir: PathBuf,
 198     pub libdir: Option<PathBuf>,
 199     pub mandir: Option<PathBuf>,
 200     pub codegen_tests: bool,
 201     pub nodejs: Option<PathBuf>,
 202     pub npm: Option<PathBuf>,
 203     pub gdb: Option<PathBuf>,
 204     pub python: Option<PathBuf>,
 205     pub cargo_native_static: bool,
 206     pub configure_args: Vec<String>,
 207
 208     // These are either the stage0 downloaded binaries or the locally installed ones.
 209     pub initial_cargo: PathBuf,
 210     pub initial_rustc: PathBuf,
 211     #[cfg(not(test))]
 212     initial_rustfmt: RefCell<RustfmtState>,
 213     #[cfg(test)]
 214     pub initial_rustfmt: RefCell<RustfmtState>,
 215     pub out: PathBuf,
 216 }
 217
 218 #[derive(Default, Deserialize)]
 219 #[cfg_attr(test, derive(Clone))]
 220 pub struct Stage0Metadata {
 221     pub config: Stage0Config,
 222     pub checksums_sha256: HashMap<String, String>,
 223     pub rustfmt: Option<RustfmtMetadata>,
 224 }
 225 #[derive(Default, Deserialize)]
 226 #[cfg_attr(test, derive(Clone))]
 227 pub struct Stage0Config {
 228     pub dist_server: String,
 229     pub artifacts_server: String,
 230     pub artifacts_with_llvm_assertions_server: String,
 231     pub git_merge_commit_email: String,
 232     pub nightly_branch: String,
 233 }
 234 #[derive(Default, Deserialize)]
 235 #[cfg_attr(test, derive(Clone))]
 236 pub struct RustfmtMetadata {
 237     pub date: String,
 238     pub version: String,
 239 }
 240
 241 #[derive(Clone, Debug)]
 242 pub enum RustfmtState {
 243     SystemToolchain(PathBuf),
 244     Downloaded(PathBuf),
 245     Unavailable,
 246     LazyEvaluated,
 247 }
 248
 249 impl Default for RustfmtState {
 250     fn default() -> Self {
 251         RustfmtState::LazyEvaluated
 252     }
 253 }
 254
 255 #[derive(Debug, Clone, Copy, PartialEq)]
 256 pub enum LlvmLibunwind {
 257     No,
 258     InTree,
 259     System,
 260 }
 261
 262 impl Default for LlvmLibunwind {
 263     fn default() -> Self {
 264         Self::No
 265     }
 266 }
 267
 268 impl FromStr for LlvmLibunwind {
 269     type Err = String;
 270
 271     fn from_str(value: &str) -> Result<Self, Self::Err> {
 272         match value {
 273             "no" => Ok(Self::No),
 274             "in-tree" => Ok(Self::InTree),
 275             "system" => Ok(Self::System),
 276             invalid => Err(format!("Invalid value '{}' for rust.llvm-libunwind config.", invalid)),
 277         }
 278     }
 279 }
 280
 281 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
 282 pub enum SplitDebuginfo {
 283     Packed,
 284     Unpacked,
 285     Off,
 286 }
 287
 288 impl Default for SplitDebuginfo {
 289     fn default() -> Self {
 290         SplitDebuginfo::Off
 291     }
 292 }
 293
 294 impl std::str::FromStr for SplitDebuginfo {
 295     type Err = ();
 296
 297     fn from_str(s: &str) -> Result<Self, Self::Err> {
 298         match s {
 299             "packed" => Ok(SplitDebuginfo::Packed),
 300             "unpacked" => Ok(SplitDebuginfo::Unpacked),
 301             "off" => Ok(SplitDebuginfo::Off),
 302             _ => Err(()),
 303         }
 304     }
 305 }
 306
 307 impl SplitDebuginfo {
 308     /// Returns the default `-Csplit-debuginfo` value for the current target. See the comment for
 309     /// `rust.split-debuginfo` in `config.toml.example`.
 310     fn default_for_platform(target: &str) -> Self {
 311         if target.contains("apple") {
 312             SplitDebuginfo::Unpacked
 313         } else if target.contains("windows") {
 314             SplitDebuginfo::Packed
 315         } else {
 316             SplitDebuginfo::Off
 317         }
 318     }
 319 }
 320
 321 /// LTO mode used for compiling rustc itself.
 322 #[derive(Default, Clone)]
 323 pub enum RustcLto {
 324     #[default]
 325     ThinLocal,
 326     Thin,
 327     Fat,
 328 }
 329
 330 impl std::str::FromStr for RustcLto {
 331     type Err = String;
 332
 333     fn from_str(s: &str) -> Result<Self, Self::Err> {
 334         match s {
 335             "thin-local" => Ok(RustcLto::ThinLocal),
 336             "thin" => Ok(RustcLto::Thin),
 337             "fat" => Ok(RustcLto::Fat),
 338             _ => Err(format!("Invalid value for rustc LTO: {}", s)),
 339         }
 340     }
 341 }
 342
 343 #[derive(Copy, Clone, Default, PartialEq, Eq, PartialOrd, Ord, Hash)]
 344 pub struct TargetSelection {
 345     pub triple: Interned<String>,
 346     file: Option<Interned<String>>,
 347 }
 348
 349 impl TargetSelection {
 350     pub fn from_user(selection: &str) -> Self {
 351         let path = Path::new(selection);
 352
 353         let (triple, file) = if path.exists() {
 354             let triple = path
 355                 .file_stem()
 356                 .expect("Target specification file has no file stem")
 357                 .to_str()
 358                 .expect("Target specification file stem is not UTF-8");
 359
 360             (triple, Some(selection))
 361         } else {
 362             (selection, None)
 363         };
 364
 365         let triple = INTERNER.intern_str(triple);
 366         let file = file.map(|f| INTERNER.intern_str(f));
 367
 368         Self { triple, file }
 369     }
 370
 371     pub fn rustc_target_arg(&self) -> &str {
 372         self.file.as_ref().unwrap_or(&self.triple)
 373     }
 374
 375     pub fn contains(&self, needle: &str) -> bool {
 376         self.triple.contains(needle)
 377     }
 378
 379     pub fn starts_with(&self, needle: &str) -> bool {
 380         self.triple.starts_with(needle)
 381     }
 382
 383     pub fn ends_with(&self, needle: &str) -> bool {
 384         self.triple.ends_with(needle)
 385     }
 386 }
 387
 388 impl fmt::Display for TargetSelection {
 389     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 390         write!(f, "{}", self.triple)?;
 391         if let Some(file) = self.file {
 392             write!(f, "({})", file)?;
 393         }
 394         Ok(())
 395     }
 396 }
 397
 398 impl fmt::Debug for TargetSelection {
 399     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 400         write!(f, "{}", self)
 401     }
 402 }
 403
 404 impl PartialEq<&str> for TargetSelection {
 405     fn eq(&self, other: &&str) -> bool {
 406         self.triple == *other
 407     }
 408 }
 409
 410 /// Per-target configuration stored in the global configuration structure.
 411 #[derive(Default)]
 412 #[cfg_attr(test, derive(Clone))]
 413 pub struct Target {
 414     /// Some(path to llvm-config) if using an external LLVM.
 415     pub llvm_config: Option<PathBuf>,
 416     pub llvm_has_rust_patches: Option<bool>,
 417     /// Some(path to FileCheck) if one was specified.
 418     pub llvm_filecheck: Option<PathBuf>,
 419     pub llvm_libunwind: Option<LlvmLibunwind>,
 420     pub cc: Option<PathBuf>,
 421     pub cxx: Option<PathBuf>,
 422     pub ar: Option<PathBuf>,
 423     pub ranlib: Option<PathBuf>,
 424     pub default_linker: Option<PathBuf>,
 425     pub linker: Option<PathBuf>,
 426     pub ndk: Option<PathBuf>,
 427     pub sanitizers: Option<bool>,
 428     pub profiler: Option<bool>,
 429     pub crt_static: Option<bool>,
 430     pub musl_root: Option<PathBuf>,
 431     pub musl_libdir: Option<PathBuf>,
 432     pub wasi_root: Option<PathBuf>,
 433     pub qemu_rootfs: Option<PathBuf>,
 434     pub no_std: bool,
 435 }
 436
 437 impl Target {
 438     pub fn from_triple(triple: &str) -> Self {
 439         let mut target: Self = Default::default();
 440         if triple.contains("-none")
 441             || triple.contains("nvptx")
 442             || triple.contains("switch")
 443             || triple.contains("-uefi")
 444         {
 445             target.no_std = true;
 446         }
 447         target
 448     }
 449 }
 450 /// Structure of the `config.toml` file that configuration is read from.
 451 ///
 452 /// This structure uses `Decodable` to automatically decode a TOML configuration
 453 /// file into this format, and then this is traversed and written into the above
 454 /// `Config` structure.
 455 #[derive(Deserialize, Default)]
 456 #[serde(deny_unknown_fields, rename_all = "kebab-case")]
 457 struct TomlConfig {
 458     changelog_seen: Option<usize>,
 459     build: Option<Build>,
 460     install: Option<Install>,
 461     llvm: Option<Llvm>,
 462     rust: Option<Rust>,
 463     target: Option<HashMap<String, TomlTarget>>,
 464     dist: Option<Dist>,
 465     profile: Option<String>,
 466 }
 467
 468 trait Merge {
 469     fn merge(&mut self, other: Self);
 470 }
 471
 472 impl Merge for TomlConfig {
 473     fn merge(
 474         &mut self,
 475         TomlConfig { build, install, llvm, rust, dist, target, profile: _, changelog_seen: _ }: Self,
 476     ) {
 477         fn do_merge<T: Merge>(x: &mut Option<T>, y: Option<T>) {
 478             if let Some(new) = y {
 479                 if let Some(original) = x {
 480                     original.merge(new);
 481                 } else {
 482                     *x = Some(new);
 483                 }
 484             }
 485         }
 486         do_merge(&mut self.build, build);
 487         do_merge(&mut self.install, install);
 488         do_merge(&mut self.llvm, llvm);
 489         do_merge(&mut self.rust, rust);
 490         do_merge(&mut self.dist, dist);
 491         assert!(target.is_none(), "merging target-specific config is not currently supported");
 492     }
 493 }
 494
 495 // We are using a decl macro instead of a derive proc macro here to reduce the compile time of
 496 // rustbuild.
 497 macro_rules! define_config {
 498     ($(#[$attr:meta])* struct $name:ident {
 499         $($field:ident: Option<$field_ty:ty> = $field_key:literal,)*
 500     }) => {
 501         $(#[$attr])*
 502         struct $name {
 503             $($field: Option<$field_ty>,)*
 504         }
 505
 506         impl Merge for $name {
 507             fn merge(&mut self, other: Self) {
 508                 $(
 509                     if !self.$field.is_some() {
 510                         self.$field = other.$field;
 511                     }
 512                 )*
 513             }
 514         }
 515
 516         // The following is a trimmed version of what serde_derive generates. All parts not relevant
 517         // for toml deserialization have been removed. This reduces the binary size and improves
 518         // compile time of rustbuild.
 519         impl<'de> Deserialize<'de> for $name {
 520             fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
 521             where
 522                 D: Deserializer<'de>,
 523             {
 524                 struct Field;
 525                 impl<'de> serde::de::Visitor<'de> for Field {
 526                     type Value = $name;
 527                     fn expecting(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
 528                         f.write_str(concat!("struct ", stringify!($name)))
 529                     }
 530
 531                     #[inline]
 532                     fn visit_map<A>(self, mut map: A) -> Result<Self::Value, A::Error>
 533                     where
 534                         A: serde::de::MapAccess<'de>,
 535                     {
 536                         $(let mut $field: Option<$field_ty> = None;)*
 537                         while let Some(key) =
 538                             match serde::de::MapAccess::next_key::<String>(&mut map) {
 539                                 Ok(val) => val,
 540                                 Err(err) => {
 541                                     return Err(err);
 542                                 }
 543                             }
 544                         {
 545                             match &*key {
 546                                 $($field_key => {
 547                                     if $field.is_some() {
 548                                         return Err(<A::Error as serde::de::Error>::duplicate_field(
 549                                             $field_key,
 550                                         ));
 551                                     }
 552                                     $field = match serde::de::MapAccess::next_value::<$field_ty>(
 553                                         &mut map,
 554                                     ) {
 555                                         Ok(val) => Some(val),
 556                                         Err(err) => {
 557                                             return Err(err);
 558                                         }
 559                                     };
 560                                 })*
 561                                 key => {
 562                                     return Err(serde::de::Error::unknown_field(key, FIELDS));
 563                                 }
 564                             }
 565                         }
 566                         Ok($name { $($field),* })
 567                     }
 568                 }
 569                 const FIELDS: &'static [&'static str] = &[
 570                     $($field_key,)*
 571                 ];
 572                 Deserializer::deserialize_struct(
 573                     deserializer,
 574                     stringify!($name),
 575                     FIELDS,
 576                     Field,
 577                 )
 578             }
 579         }
 580     }
 581 }
 582
 583 define_config! {
 584     /// TOML representation of various global build decisions.
 585     #[derive(Default)]
 586     struct Build {
 587         build: Option<String> = "build",
 588         host: Option<Vec<String>> = "host",
 589         target: Option<Vec<String>> = "target",
 590         build_dir: Option<String> = "build-dir",
 591         cargo: Option<String> = "cargo",
 592         rustc: Option<String> = "rustc",
 593         rustfmt: Option<PathBuf> = "rustfmt",
 594         docs: Option<bool> = "docs",
 595         compiler_docs: Option<bool> = "compiler-docs",
 596         docs_minification: Option<bool> = "docs-minification",
 597         submodules: Option<bool> = "submodules",
 598         gdb: Option<String> = "gdb",
 599         nodejs: Option<String> = "nodejs",
 600         npm: Option<String> = "npm",
 601         python: Option<String> = "python",
 602         locked_deps: Option<bool> = "locked-deps",
 603         vendor: Option<bool> = "vendor",
 604         full_bootstrap: Option<bool> = "full-bootstrap",
 605         extended: Option<bool> = "extended",
 606         tools: Option<HashSet<String>> = "tools",
 607         verbose: Option<usize> = "verbose",
 608         sanitizers: Option<bool> = "sanitizers",
 609         profiler: Option<bool> = "profiler",
 610         cargo_native_static: Option<bool> = "cargo-native-static",
 611         low_priority: Option<bool> = "low-priority",
 612         configure_args: Option<Vec<String>> = "configure-args",
 613         local_rebuild: Option<bool> = "local-rebuild",
 614         print_step_timings: Option<bool> = "print-step-timings",
 615         print_step_rusage: Option<bool> = "print-step-rusage",
 616         check_stage: Option<u32> = "check-stage",
 617         doc_stage: Option<u32> = "doc-stage",
 618         build_stage: Option<u32> = "build-stage",
 619         test_stage: Option<u32> = "test-stage",
 620         install_stage: Option<u32> = "install-stage",
 621         dist_stage: Option<u32> = "dist-stage",
 622         bench_stage: Option<u32> = "bench-stage",
 623         patch_binaries_for_nix: Option<bool> = "patch-binaries-for-nix",
 624         metrics: Option<bool> = "metrics",
 625     }
 626 }
 627
 628 define_config! {
 629     /// TOML representation of various global install decisions.
 630     struct Install {
 631         prefix: Option<String> = "prefix",
 632         sysconfdir: Option<String> = "sysconfdir",
 633         docdir: Option<String> = "docdir",
 634         bindir: Option<String> = "bindir",
 635         libdir: Option<String> = "libdir",
 636         mandir: Option<String> = "mandir",
 637         datadir: Option<String> = "datadir",
 638     }
 639 }
 640
 641 define_config! {
 642     /// TOML representation of how the LLVM build is configured.
 643     struct Llvm {
 644         skip_rebuild: Option<bool> = "skip-rebuild",
 645         optimize: Option<bool> = "optimize",
 646         thin_lto: Option<bool> = "thin-lto",
 647         release_debuginfo: Option<bool> = "release-debuginfo",
 648         assertions: Option<bool> = "assertions",
 649         tests: Option<bool> = "tests",
 650         plugins: Option<bool> = "plugins",
 651         ccache: Option<StringOrBool> = "ccache",
 652         version_check: Option<bool> = "version-check",
 653         static_libstdcpp: Option<bool> = "static-libstdcpp",
 654         ninja: Option<bool> = "ninja",
 655         targets: Option<String> = "targets",
 656         experimental_targets: Option<String> = "experimental-targets",
 657         link_jobs: Option<u32> = "link-jobs",
 658         link_shared: Option<bool> = "link-shared",
 659         version_suffix: Option<String> = "version-suffix",
 660         clang_cl: Option<String> = "clang-cl",
 661         cflags: Option<String> = "cflags",
 662         cxxflags: Option<String> = "cxxflags",
 663         ldflags: Option<String> = "ldflags",
 664         use_libcxx: Option<bool> = "use-libcxx",
 665         use_linker: Option<String> = "use-linker",
 666         allow_old_toolchain: Option<bool> = "allow-old-toolchain",
 667         polly: Option<bool> = "polly",
 668         clang: Option<bool> = "clang",
 669         download_ci_llvm: Option<StringOrBool> = "download-ci-llvm",
 670         build_config: Option<HashMap<String, String>> = "build-config",
 671     }
 672 }
 673
 674 define_config! {
 675     struct Dist {
 676         sign_folder: Option<String> = "sign-folder",
 677         gpg_password_file: Option<String> = "gpg-password-file",
 678         upload_addr: Option<String> = "upload-addr",
 679         src_tarball: Option<bool> = "src-tarball",
 680         missing_tools: Option<bool> = "missing-tools",
 681         compression_formats: Option<Vec<String>> = "compression-formats",
 682     }
 683 }
 684
 685 #[derive(Deserialize)]
 686 #[serde(untagged)]
 687 enum StringOrBool {
 688     String(String),
 689     Bool(bool),
 690 }
 691
 692 impl Default for StringOrBool {
 693     fn default() -> StringOrBool {
 694         StringOrBool::Bool(false)
 695     }
 696 }
 697
 698 define_config! {
 699     /// TOML representation of how the Rust build is configured.
 700     struct Rust {
 701         optimize: Option<bool> = "optimize",
 702         debug: Option<bool> = "debug",
 703         codegen_units: Option<u32> = "codegen-units",
 704         codegen_units_std: Option<u32> = "codegen-units-std",
 705         debug_assertions: Option<bool> = "debug-assertions",
 706         debug_assertions_std: Option<bool> = "debug-assertions-std",
 707         overflow_checks: Option<bool> = "overflow-checks",
 708         overflow_checks_std: Option<bool> = "overflow-checks-std",
 709         debug_logging: Option<bool> = "debug-logging",
 710         debuginfo_level: Option<u32> = "debuginfo-level",
 711         debuginfo_level_rustc: Option<u32> = "debuginfo-level-rustc",
 712         debuginfo_level_std: Option<u32> = "debuginfo-level-std",
 713         debuginfo_level_tools: Option<u32> = "debuginfo-level-tools",
 714         debuginfo_level_tests: Option<u32> = "debuginfo-level-tests",
 715         split_debuginfo: Option<String> = "split-debuginfo",
 716         run_dsymutil: Option<bool> = "run-dsymutil",
 717         backtrace: Option<bool> = "backtrace",
 718         incremental: Option<bool> = "incremental",
 719         parallel_compiler: Option<bool> = "parallel-compiler",
 720         default_linker: Option<String> = "default-linker",
 721         channel: Option<String> = "channel",
 722         description: Option<String> = "description",
 723         musl_root: Option<String> = "musl-root",
 724         rpath: Option<bool> = "rpath",
 725         verbose_tests: Option<bool> = "verbose-tests",
 726         optimize_tests: Option<bool> = "optimize-tests",
 727         codegen_tests: Option<bool> = "codegen-tests",
 728         ignore_git: Option<bool> = "ignore-git",
 729         dist_src: Option<bool> = "dist-src",
 730         save_toolstates: Option<String> = "save-toolstates",
 731         codegen_backends: Option<Vec<String>> = "codegen-backends",
 732         lld: Option<bool> = "lld",
 733         use_lld: Option<bool> = "use-lld",
 734         llvm_tools: Option<bool> = "llvm-tools",
 735         deny_warnings: Option<bool> = "deny-warnings",
 736         backtrace_on_ice: Option<bool> = "backtrace-on-ice",
 737         verify_llvm_ir: Option<bool> = "verify-llvm-ir",
 738         thin_lto_import_instr_limit: Option<u32> = "thin-lto-import-instr-limit",
 739         remap_debuginfo: Option<bool> = "remap-debuginfo",
 740         jemalloc: Option<bool> = "jemalloc",
 741         test_compare_mode: Option<bool> = "test-compare-mode",
 742         llvm_libunwind: Option<String> = "llvm-libunwind",
 743         control_flow_guard: Option<bool> = "control-flow-guard",
 744         new_symbol_mangling: Option<bool> = "new-symbol-mangling",
 745         profile_generate: Option<String> = "profile-generate",
 746         profile_use: Option<String> = "profile-use",
 747         // ignored; this is set from an env var set by bootstrap.py
 748         download_rustc: Option<StringOrBool> = "download-rustc",
 749         lto: Option<String> = "lto",
 750     }
 751 }
 752
 753 define_config! {
 754     /// TOML representation of how each build target is configured.
 755     struct TomlTarget {
 756         cc: Option<String> = "cc",
 757         cxx: Option<String> = "cxx",
 758         ar: Option<String> = "ar",
 759         ranlib: Option<String> = "ranlib",
 760         default_linker: Option<PathBuf> = "default-linker",
 761         linker: Option<String> = "linker",
 762         llvm_config: Option<String> = "llvm-config",
 763         llvm_has_rust_patches: Option<bool> = "llvm-has-rust-patches",
 764         llvm_filecheck: Option<String> = "llvm-filecheck",
 765         llvm_libunwind: Option<String> = "llvm-libunwind",
 766         android_ndk: Option<String> = "android-ndk",
 767         sanitizers: Option<bool> = "sanitizers",
 768         profiler: Option<bool> = "profiler",
 769         crt_static: Option<bool> = "crt-static",
 770         musl_root: Option<String> = "musl-root",
 771         musl_libdir: Option<String> = "musl-libdir",
 772         wasi_root: Option<String> = "wasi-root",
 773         qemu_rootfs: Option<String> = "qemu-rootfs",
 774         no_std: Option<bool> = "no-std",
 775     }
 776 }
 777
 778 impl Config {
 779     pub fn default_opts() -> Config {
 780         let mut config = Config::default();
 781         config.llvm_optimize = true;
 782         config.ninja_in_file = true;
 783         config.llvm_version_check = true;
 784         config.llvm_static_stdcpp = true;
 785         config.backtrace = true;
 786         config.rust_optimize = true;
 787         config.rust_optimize_tests = true;
 788         config.submodules = None;
 789         config.docs = true;
 790         config.docs_minification = true;
 791         config.rust_rpath = true;
 792         config.channel = "dev".to_string();
 793         config.codegen_tests = true;
 794         config.rust_dist_src = true;
 795         config.rust_codegen_backends = vec![INTERNER.intern_str("llvm")];
 796         config.deny_warnings = true;
 797         config.bindir = "bin".into();
 798
 799         // set by build.rs
 800         config.build = TargetSelection::from_user(&env!("BUILD_TRIPLE"));
 801
 802         let manifest_dir = PathBuf::from(env!("CARGO_MANIFEST_DIR"));
 803         // Undo `src/bootstrap`
 804         config.src = manifest_dir.parent().unwrap().parent().unwrap().to_owned();
 805         config.out = PathBuf::from("build");
 806
 807         config
 808     }
 809
 810     pub fn parse(args: &[String]) -> Config {
 811         let flags = Flags::parse(&args);
 812         let mut config = Config::default_opts();
 813
 814         // Set flags.
 815         config.exclude = flags.exclude.into_iter().map(|path| TaskPath::parse(path)).collect();
 816         config.include_default_paths = flags.include_default_paths;
 817         config.rustc_error_format = flags.rustc_error_format;
 818         config.json_output = flags.json_output;
 819         config.on_fail = flags.on_fail;
 820         config.jobs = flags.jobs.map(threads_from_config);
 821         config.cmd = flags.cmd;
 822         config.incremental = flags.incremental;
 823         config.dry_run = flags.dry_run;
 824         config.keep_stage = flags.keep_stage;
 825         config.keep_stage_std = flags.keep_stage_std;
 826         config.color = flags.color;
 827         if let Some(value) = flags.deny_warnings {
 828             config.deny_warnings = value;
 829         }
 830         config.llvm_profile_use = flags.llvm_profile_use;
 831         config.llvm_profile_generate = flags.llvm_profile_generate;
 832         config.llvm_bolt_profile_generate = flags.llvm_bolt_profile_generate;
 833         config.llvm_bolt_profile_use = flags.llvm_bolt_profile_use;
 834
 835         if config.llvm_bolt_profile_generate && config.llvm_bolt_profile_use.is_some() {
 836             eprintln!(
 837                 "Cannot use both `llvm_bolt_profile_generate` and `llvm_bolt_profile_use` at the same time"
 838             );
 839             crate::detail_exit(1);
 840         }
 841
 842         // Infer the rest of the configuration.
 843
 844         // Infer the source directory. This is non-trivial because we want to support a downloaded bootstrap binary,
 845         // running on a completely machine from where it was compiled.
 846         let mut cmd = Command::new("git");
 847         // NOTE: we cannot support running from outside the repository because the only path we have available
 848         // is set at compile time, which can be wrong if bootstrap was downloaded from source.
 849         // We still support running outside the repository if we find we aren't in a git directory.
 850         cmd.arg("rev-parse").arg("--show-toplevel");
 851         // Discard stderr because we expect this to fail when building from a tarball.
 852         let output = cmd
 853             .stderr(std::process::Stdio::null())
 854             .output()
 855             .ok()
 856             .and_then(|output| if output.status.success() { Some(output) } else { None });
 857         if let Some(output) = output {
 858             let git_root = String::from_utf8(output.stdout).unwrap();
 859             // We need to canonicalize this path to make sure it uses backslashes instead of forward slashes.
 860             let git_root = PathBuf::from(git_root.trim()).canonicalize().unwrap();
 861             let s = git_root.to_str().unwrap();
 862
 863             // Bootstrap is quite bad at handling /? in front of paths
 864             let src = match s.strip_prefix("\\\\?\\") {
 865                 Some(p) => PathBuf::from(p),
 866                 None => PathBuf::from(git_root),
 867             };
 868             // If this doesn't have at least `stage0.json`, we guessed wrong. This can happen when,
 869             // for example, the build directory is inside of another unrelated git directory.
 870             // In that case keep the original `CARGO_MANIFEST_DIR` handling.
 871             //
 872             // NOTE: this implies that downloadable bootstrap isn't supported when the build directory is outside
 873             // the source directory. We could fix that by setting a variable from all three of python, ./x, and x.ps1.
 874             if src.join("src").join("stage0.json").exists() {
 875                 config.src = src;
 876             }
 877         } else {
 878             // We're building from a tarball, not git sources.
 879             // We don't support pre-downloaded bootstrap in this case.
 880         }
 881
 882         if cfg!(test) {
 883             // Use the build directory of the original x.py invocation, so that we can set `initial_rustc` properly.
 884             config.out = Path::new(
 885                 &env::var_os("CARGO_TARGET_DIR").expect("cargo test directly is not supported"),
 886             )
 887             .parent()
 888             .unwrap()
 889             .to_path_buf();
 890         }
 891
 892         let stage0_json = t!(std::fs::read(&config.src.join("src").join("stage0.json")));
 893
 894         config.stage0_metadata = t!(serde_json::from_slice::<Stage0Metadata>(&stage0_json));
 895
 896         #[cfg(test)]
 897         let get_toml = |_| TomlConfig::default();
 898         #[cfg(not(test))]
 899         let get_toml = |file: &Path| {
 900             let contents =
 901                 t!(fs::read_to_string(file), format!("config file {} not found", file.display()));
 902             // Deserialize to Value and then TomlConfig to prevent the Deserialize impl of
 903             // TomlConfig and sub types to be monomorphized 5x by toml.
 904             match toml::from_str(&contents)
 905                 .and_then(|table: toml::Value| TomlConfig::deserialize(table))
 906             {
 907                 Ok(table) => table,
 908                 Err(err) => {
 909                     eprintln!("failed to parse TOML configuration '{}': {}", file.display(), err);
 910                     crate::detail_exit(2);
 911                 }
 912             }
 913         };
 914
 915         // Read from `--config`, then `RUST_BOOTSTRAP_CONFIG`, then `./config.toml`, then `config.toml` in the root directory.
 916         let toml_path = flags
 917             .config
 918             .clone()
 919             .or_else(|| env::var_os("RUST_BOOTSTRAP_CONFIG").map(PathBuf::from));
 920         let using_default_path = toml_path.is_none();
 921         let mut toml_path = toml_path.unwrap_or_else(|| PathBuf::from("config.toml"));
 922         if using_default_path && !toml_path.exists() {
 923             toml_path = config.src.join(toml_path);
 924         }
 925
 926         // Give a hard error if `--config` or `RUST_BOOTSTRAP_CONFIG` are set to a missing path,
 927         // but not if `config.toml` hasn't been created.
 928         let mut toml = if !using_default_path || toml_path.exists() {
 929             get_toml(&toml_path)
 930         } else {
 931             TomlConfig::default()
 932         };
 933
 934         if let Some(include) = &toml.profile {
 935             let mut include_path = config.src.clone();
 936             include_path.push("src");
 937             include_path.push("bootstrap");
 938             include_path.push("defaults");
 939             include_path.push(format!("config.{}.toml", include));
 940             let included_toml = get_toml(&include_path);
 941             toml.merge(included_toml);
 942         }
 943
 944         config.changelog_seen = toml.changelog_seen;
 945         config.config = toml_path;
 946
 947         let build = toml.build.unwrap_or_default();
 948
 949         set(&mut config.out, flags.build_dir.or_else(|| build.build_dir.map(PathBuf::from)));
 950         // NOTE: Bootstrap spawns various commands with different working directories.
 951         // To avoid writing to random places on the file system, `config.out` needs to be an absolute path.
 952         if !config.out.is_absolute() {
 953             // `canonicalize` requires the path to already exist. Use our vendored copy of `absolute` instead.
 954             config.out = crate::util::absolute(&config.out);
 955         }
 956
 957         config.initial_rustc = build
 958             .rustc
 959             .map(PathBuf::from)
 960             .unwrap_or_else(|| config.out.join(config.build.triple).join("stage0/bin/rustc"));
 961         config.initial_cargo = build
 962             .cargo
 963             .map(PathBuf::from)
 964             .unwrap_or_else(|| config.out.join(config.build.triple).join("stage0/bin/cargo"));
 965
 966         // NOTE: it's important this comes *after* we set `initial_rustc` just above.
 967         if config.dry_run {
 968             let dir = config.out.join("tmp-dry-run");
 969             t!(fs::create_dir_all(&dir));
 970             config.out = dir;
 971         }
 972
 973         config.hosts = if let Some(arg_host) = flags.host {
 974             arg_host
 975         } else if let Some(file_host) = build.host {
 976             file_host.iter().map(|h| TargetSelection::from_user(h)).collect()
 977         } else {
 978             vec![config.build]
 979         };
 980         config.targets = if let Some(arg_target) = flags.target {
 981             arg_target
 982         } else if let Some(file_target) = build.target {
 983             file_target.iter().map(|h| TargetSelection::from_user(h)).collect()
 984         } else {
 985             // If target is *not* configured, then default to the host
 986             // toolchains.
 987             config.hosts.clone()
 988         };
 989
 990         config.nodejs = build.nodejs.map(PathBuf::from);
 991         config.npm = build.npm.map(PathBuf::from);
 992         config.gdb = build.gdb.map(PathBuf::from);
 993         config.python = build.python.map(PathBuf::from);
 994         config.submodules = build.submodules;
 995         set(&mut config.low_priority, build.low_priority);
 996         set(&mut config.compiler_docs, build.compiler_docs);
 997         set(&mut config.docs_minification, build.docs_minification);
 998         set(&mut config.docs, build.docs);
 999         set(&mut config.locked_deps, build.locked_deps);
1000         set(&mut config.vendor, build.vendor);
1001         set(&mut config.full_bootstrap, build.full_bootstrap);
1002         set(&mut config.extended, build.extended);
1003         config.tools = build.tools;
1004         set(&mut config.verbose, build.verbose);
1005         set(&mut config.sanitizers, build.sanitizers);
1006         set(&mut config.profiler, build.profiler);
1007         set(&mut config.cargo_native_static, build.cargo_native_static);
1008         set(&mut config.configure_args, build.configure_args);
1009         set(&mut config.local_rebuild, build.local_rebuild);
1010         set(&mut config.print_step_timings, build.print_step_timings);
1011         set(&mut config.print_step_rusage, build.print_step_rusage);
1012         set(&mut config.patch_binaries_for_nix, build.patch_binaries_for_nix);
1013
1014         config.verbose = cmp::max(config.verbose, flags.verbose);
1015
1016         if let Some(install) = toml.install {
1017             config.prefix = install.prefix.map(PathBuf::from);
1018             config.sysconfdir = install.sysconfdir.map(PathBuf::from);
1019             config.datadir = install.datadir.map(PathBuf::from);
1020             config.docdir = install.docdir.map(PathBuf::from);
1021             set(&mut config.bindir, install.bindir.map(PathBuf::from));
1022             config.libdir = install.libdir.map(PathBuf::from);
1023             config.mandir = install.mandir.map(PathBuf::from);
1024         }
1025
1026         // We want the llvm-skip-rebuild flag to take precedence over the
1027         // skip-rebuild config.toml option so we store it separately
1028         // so that we can infer the right value
1029         let mut llvm_skip_rebuild = flags.llvm_skip_rebuild;
1030
1031         // Store off these values as options because if they're not provided
1032         // we'll infer default values for them later
1033         let mut llvm_assertions = None;
1034         let mut llvm_tests = None;
1035         let mut llvm_plugins = None;
1036         let mut debug = None;
1037         let mut debug_assertions = None;
1038         let mut debug_assertions_std = None;
1039         let mut overflow_checks = None;
1040         let mut overflow_checks_std = None;
1041         let mut debug_logging = None;
1042         let mut debuginfo_level = None;
1043         let mut debuginfo_level_rustc = None;
1044         let mut debuginfo_level_std = None;
1045         let mut debuginfo_level_tools = None;
1046         let mut debuginfo_level_tests = None;
1047         let mut optimize = None;
1048         let mut ignore_git = None;
1049
1050         if let Some(llvm) = toml.llvm {
1051             match llvm.ccache {
1052                 Some(StringOrBool::String(ref s)) => config.ccache = Some(s.to_string()),
1053                 Some(StringOrBool::Bool(true)) => {
1054                     config.ccache = Some("ccache".to_string());
1055                 }
1056                 Some(StringOrBool::Bool(false)) | None => {}
1057             }
1058             set(&mut config.ninja_in_file, llvm.ninja);
1059             llvm_assertions = llvm.assertions;
1060             llvm_tests = llvm.tests;
1061             llvm_plugins = llvm.plugins;
1062             llvm_skip_rebuild = llvm_skip_rebuild.or(llvm.skip_rebuild);
1063             set(&mut config.llvm_optimize, llvm.optimize);
1064             set(&mut config.llvm_thin_lto, llvm.thin_lto);
1065             set(&mut config.llvm_release_debuginfo, llvm.release_debuginfo);
1066             set(&mut config.llvm_version_check, llvm.version_check);
1067             set(&mut config.llvm_static_stdcpp, llvm.static_libstdcpp);
1068             if let Some(v) = llvm.link_shared {
1069                 config.llvm_link_shared.set(Some(v));
1070             }
1071             config.llvm_targets = llvm.targets.clone();
1072             config.llvm_experimental_targets = llvm.experimental_targets.clone();
1073             config.llvm_link_jobs = llvm.link_jobs;
1074             config.llvm_version_suffix = llvm.version_suffix.clone();
1075             config.llvm_clang_cl = llvm.clang_cl.clone();
1076
1077             config.llvm_cflags = llvm.cflags.clone();
1078             config.llvm_cxxflags = llvm.cxxflags.clone();
1079             config.llvm_ldflags = llvm.ldflags.clone();
1080             set(&mut config.llvm_use_libcxx, llvm.use_libcxx);
1081             config.llvm_use_linker = llvm.use_linker.clone();
1082             config.llvm_allow_old_toolchain = llvm.allow_old_toolchain.unwrap_or(false);
1083             config.llvm_polly = llvm.polly.unwrap_or(false);
1084             config.llvm_clang = llvm.clang.unwrap_or(false);
1085             config.llvm_build_config = llvm.build_config.clone().unwrap_or(Default::default());
1086             config.llvm_from_ci = match llvm.download_ci_llvm {
1087                 Some(StringOrBool::String(s)) => {
1088                     assert!(s == "if-available", "unknown option `{}` for download-ci-llvm", s);
1089                     crate::native::is_ci_llvm_available(&config, llvm_assertions.unwrap_or(false))
1090                 }
1091                 Some(StringOrBool::Bool(b)) => b,
1092                 None => false,
1093             };
1094
1095             if config.llvm_from_ci {
1096                 // None of the LLVM options, except assertions, are supported
1097                 // when using downloaded LLVM. We could just ignore these but
1098                 // that's potentially confusing, so force them to not be
1099                 // explicitly set. The defaults and CI defaults don't
1100                 // necessarily match but forcing people to match (somewhat
1101                 // arbitrary) CI configuration locally seems bad/hard.
1102                 check_ci_llvm!(llvm.optimize);
1103                 check_ci_llvm!(llvm.thin_lto);
1104                 check_ci_llvm!(llvm.release_debuginfo);
1105                 // CI-built LLVM can be either dynamic or static. We won't know until we download it.
1106                 check_ci_llvm!(llvm.link_shared);
1107                 check_ci_llvm!(llvm.static_libstdcpp);
1108                 check_ci_llvm!(llvm.targets);
1109                 check_ci_llvm!(llvm.experimental_targets);
1110                 check_ci_llvm!(llvm.link_jobs);
1111                 check_ci_llvm!(llvm.clang_cl);
1112                 check_ci_llvm!(llvm.version_suffix);
1113                 check_ci_llvm!(llvm.cflags);
1114                 check_ci_llvm!(llvm.cxxflags);
1115                 check_ci_llvm!(llvm.ldflags);
1116                 check_ci_llvm!(llvm.use_libcxx);
1117                 check_ci_llvm!(llvm.use_linker);
1118                 check_ci_llvm!(llvm.allow_old_toolchain);
1119                 check_ci_llvm!(llvm.polly);
1120                 check_ci_llvm!(llvm.clang);
1121                 check_ci_llvm!(llvm.build_config);
1122                 check_ci_llvm!(llvm.plugins);
1123             }
1124
1125             // NOTE: can never be hit when downloading from CI, since we call `check_ci_llvm!(thin_lto)` above.
1126             if config.llvm_thin_lto && llvm.link_shared.is_none() {
1127                 // If we're building with ThinLTO on, by default we want to link
1128                 // to LLVM shared, to avoid re-doing ThinLTO (which happens in
1129                 // the link step) with each stage.
1130                 config.llvm_link_shared.set(Some(true));
1131             }
1132         }
1133
1134         if let Some(rust) = toml.rust {
1135             debug = rust.debug;
1136             debug_assertions = rust.debug_assertions;
1137             debug_assertions_std = rust.debug_assertions_std;
1138             overflow_checks = rust.overflow_checks;
1139             overflow_checks_std = rust.overflow_checks_std;
1140             debug_logging = rust.debug_logging;
1141             debuginfo_level = rust.debuginfo_level;
1142             debuginfo_level_rustc = rust.debuginfo_level_rustc;
1143             debuginfo_level_std = rust.debuginfo_level_std;
1144             debuginfo_level_tools = rust.debuginfo_level_tools;
1145             debuginfo_level_tests = rust.debuginfo_level_tests;
1146             config.rust_split_debuginfo = rust
1147                 .split_debuginfo
1148                 .as_deref()
1149                 .map(SplitDebuginfo::from_str)
1150                 .map(|v| v.expect("invalid value for rust.split_debuginfo"))
1151                 .unwrap_or(SplitDebuginfo::default_for_platform(&config.build.triple));
1152             optimize = rust.optimize;
1153             ignore_git = rust.ignore_git;
1154             config.rust_new_symbol_mangling = rust.new_symbol_mangling;
1155             set(&mut config.rust_optimize_tests, rust.optimize_tests);
1156             set(&mut config.codegen_tests, rust.codegen_tests);
1157             set(&mut config.rust_rpath, rust.rpath);
1158             set(&mut config.jemalloc, rust.jemalloc);
1159             set(&mut config.test_compare_mode, rust.test_compare_mode);
1160             set(&mut config.backtrace, rust.backtrace);
1161             set(&mut config.channel, rust.channel);
1162             config.description = rust.description;
1163             set(&mut config.rust_dist_src, rust.dist_src);
1164             set(&mut config.verbose_tests, rust.verbose_tests);
1165             // in the case "false" is set explicitly, do not overwrite the command line args
1166             if let Some(true) = rust.incremental {
1167                 config.incremental = true;
1168             }
1169             set(&mut config.use_lld, rust.use_lld);
1170             set(&mut config.lld_enabled, rust.lld);
1171             set(&mut config.llvm_tools_enabled, rust.llvm_tools);
1172             config.rustc_parallel = rust.parallel_compiler.unwrap_or(false);
1173             config.rustc_default_linker = rust.default_linker;
1174             config.musl_root = rust.musl_root.map(PathBuf::from);
1175             config.save_toolstates = rust.save_toolstates.map(PathBuf::from);
1176             set(&mut config.deny_warnings, flags.deny_warnings.or(rust.deny_warnings));
1177             set(&mut config.backtrace_on_ice, rust.backtrace_on_ice);
1178             set(&mut config.rust_verify_llvm_ir, rust.verify_llvm_ir);
1179             config.rust_thin_lto_import_instr_limit = rust.thin_lto_import_instr_limit;
1180             set(&mut config.rust_remap_debuginfo, rust.remap_debuginfo);
1181             set(&mut config.control_flow_guard, rust.control_flow_guard);
1182             config.llvm_libunwind_default = rust
1183                 .llvm_libunwind
1184                 .map(|v| v.parse().expect("failed to parse rust.llvm-libunwind"));
1185
1186             if let Some(ref backends) = rust.codegen_backends {
1187                 config.rust_codegen_backends =
1188                     backends.iter().map(|s| INTERNER.intern_str(s)).collect();
1189             }
1190
1191             config.rust_codegen_units = rust.codegen_units.map(threads_from_config);
1192             config.rust_codegen_units_std = rust.codegen_units_std.map(threads_from_config);
1193             config.rust_profile_use = flags.rust_profile_use.or(rust.profile_use);
1194             config.rust_profile_generate = flags.rust_profile_generate.or(rust.profile_generate);
1195             config.download_rustc_commit = download_ci_rustc_commit(&config, rust.download_rustc);
1196
1197             config.rust_lto = rust
1198                 .lto
1199                 .as_deref()
1200                 .map(|value| RustcLto::from_str(value).unwrap())
1201                 .unwrap_or_default();
1202         } else {
1203             config.rust_profile_use = flags.rust_profile_use;
1204             config.rust_profile_generate = flags.rust_profile_generate;
1205         }
1206
1207         if let Some(t) = toml.target {
1208             for (triple, cfg) in t {
1209                 let mut target = Target::from_triple(&triple);
1210
1211                 if let Some(ref s) = cfg.llvm_config {
1212                     target.llvm_config = Some(config.src.join(s));
1213                 }
1214                 target.llvm_has_rust_patches = cfg.llvm_has_rust_patches;
1215                 if let Some(ref s) = cfg.llvm_filecheck {
1216                     target.llvm_filecheck = Some(config.src.join(s));
1217                 }
1218                 target.llvm_libunwind = cfg
1219                     .llvm_libunwind
1220                     .as_ref()
1221                     .map(|v| v.parse().expect("failed to parse rust.llvm-libunwind"));
1222                 if let Some(ref s) = cfg.android_ndk {
1223                     target.ndk = Some(config.src.join(s));
1224                 }
1225                 if let Some(s) = cfg.no_std {
1226                     target.no_std = s;
1227                 }
1228                 target.cc = cfg.cc.map(PathBuf::from);
1229                 target.cxx = cfg.cxx.map(PathBuf::from);
1230                 target.ar = cfg.ar.map(PathBuf::from);
1231                 target.ranlib = cfg.ranlib.map(PathBuf::from);
1232                 target.linker = cfg.linker.map(PathBuf::from);
1233                 target.crt_static = cfg.crt_static;
1234                 target.musl_root = cfg.musl_root.map(PathBuf::from);
1235                 target.musl_libdir = cfg.musl_libdir.map(PathBuf::from);
1236                 target.wasi_root = cfg.wasi_root.map(PathBuf::from);
1237                 target.qemu_rootfs = cfg.qemu_rootfs.map(PathBuf::from);
1238                 target.sanitizers = cfg.sanitizers;
1239                 target.profiler = cfg.profiler;
1240
1241                 config.target_config.insert(TargetSelection::from_user(&triple), target);
1242             }
1243         }
1244
1245         if config.llvm_from_ci {
1246             let triple = &config.build.triple;
1247             let ci_llvm_bin = config.ci_llvm_root().join("bin");
1248             let mut build_target = config
1249                 .target_config
1250                 .entry(config.build)
1251                 .or_insert_with(|| Target::from_triple(&triple));
1252
1253             check_ci_llvm!(build_target.llvm_config);
1254             check_ci_llvm!(build_target.llvm_filecheck);
1255             build_target.llvm_config = Some(ci_llvm_bin.join(exe("llvm-config", config.build)));
1256             build_target.llvm_filecheck = Some(ci_llvm_bin.join(exe("FileCheck", config.build)));
1257         }
1258
1259         if let Some(t) = toml.dist {
1260             config.dist_sign_folder = t.sign_folder.map(PathBuf::from);
1261             config.dist_upload_addr = t.upload_addr;
1262             config.dist_compression_formats = t.compression_formats;
1263             set(&mut config.rust_dist_src, t.src_tarball);
1264             set(&mut config.missing_tools, t.missing_tools);
1265         }
1266
1267         if let Some(r) = build.rustfmt {
1268             *config.initial_rustfmt.borrow_mut() = if r.exists() {
1269                 RustfmtState::SystemToolchain(r)
1270             } else {
1271                 RustfmtState::Unavailable
1272             };
1273         } else {
1274             // If using a system toolchain for bootstrapping, see if that has rustfmt available.
1275             let host = config.build;
1276             let rustfmt_path = config.initial_rustc.with_file_name(exe("rustfmt", host));
1277             let bin_root = config.out.join(host.triple).join("stage0");
1278             if !rustfmt_path.starts_with(&bin_root) {
1279                 // Using a system-provided toolchain; we shouldn't download rustfmt.
1280                 *config.initial_rustfmt.borrow_mut() = RustfmtState::SystemToolchain(rustfmt_path);
1281             }
1282         }
1283
1284         // Now that we've reached the end of our configuration, infer the
1285         // default values for all options that we haven't otherwise stored yet.
1286
1287         config.llvm_skip_rebuild = llvm_skip_rebuild.unwrap_or(false);
1288         config.llvm_assertions = llvm_assertions.unwrap_or(false);
1289         config.llvm_tests = llvm_tests.unwrap_or(false);
1290         config.llvm_plugins = llvm_plugins.unwrap_or(false);
1291         config.rust_optimize = optimize.unwrap_or(true);
1292
1293         let default = debug == Some(true);
1294         config.rust_debug_assertions = debug_assertions.unwrap_or(default);
1295         config.rust_debug_assertions_std =
1296             debug_assertions_std.unwrap_or(config.rust_debug_assertions);
1297         config.rust_overflow_checks = overflow_checks.unwrap_or(default);
1298         config.rust_overflow_checks_std =
1299             overflow_checks_std.unwrap_or(config.rust_overflow_checks);
1300
1301         config.rust_debug_logging = debug_logging.unwrap_or(config.rust_debug_assertions);
1302
1303         let with_defaults = |debuginfo_level_specific: Option<u32>| {
1304             debuginfo_level_specific.or(debuginfo_level).unwrap_or(if debug == Some(true) {
1305                 1
1306             } else {
1307                 0
1308             })
1309         };
1310         config.rust_debuginfo_level_rustc = with_defaults(debuginfo_level_rustc);
1311         config.rust_debuginfo_level_std = with_defaults(debuginfo_level_std);
1312         config.rust_debuginfo_level_tools = with_defaults(debuginfo_level_tools);
1313         config.rust_debuginfo_level_tests = debuginfo_level_tests.unwrap_or(0);
1314
1315         let default = config.channel == "dev";
1316         config.ignore_git = ignore_git.unwrap_or(default);
1317
1318         let download_rustc = config.download_rustc_commit.is_some();
1319         // See https://github.com/rust-lang/compiler-team/issues/326
1320         config.stage = match config.cmd {
1321             Subcommand::Check { .. } => flags.stage.or(build.check_stage).unwrap_or(0),
1322             // `download-rustc` only has a speed-up for stage2 builds. Default to stage2 unless explicitly overridden.
1323             Subcommand::Doc { .. } => {
1324                 flags.stage.or(build.doc_stage).unwrap_or(if download_rustc { 2 } else { 0 })
1325             }
1326             Subcommand::Build { .. } => {
1327                 flags.stage.or(build.build_stage).unwrap_or(if download_rustc { 2 } else { 1 })
1328             }
1329             Subcommand::Test { .. } => {
1330                 flags.stage.or(build.test_stage).unwrap_or(if download_rustc { 2 } else { 1 })
1331             }
1332             Subcommand::Bench { .. } => flags.stage.or(build.bench_stage).unwrap_or(2),
1333             Subcommand::Dist { .. } => flags.stage.or(build.dist_stage).unwrap_or(2),
1334             Subcommand::Install { .. } => flags.stage.or(build.install_stage).unwrap_or(2),
1335             // These are all bootstrap tools, which don't depend on the compiler.
1336             // The stage we pass shouldn't matter, but use 0 just in case.
1337             Subcommand::Clean { .. }
1338             | Subcommand::Clippy { .. }
1339             | Subcommand::Fix { .. }
1340             | Subcommand::Run { .. }
1341             | Subcommand::Setup { .. }
1342             | Subcommand::Format { .. } => flags.stage.unwrap_or(0),
1343         };
1344
1345         // CI should always run stage 2 builds, unless it specifically states otherwise
1346         #[cfg(not(test))]
1347         if flags.stage.is_none() && crate::CiEnv::current() != crate::CiEnv::None {
1348             match config.cmd {
1349                 Subcommand::Test { .. }
1350                 | Subcommand::Doc { .. }
1351                 | Subcommand::Build { .. }
1352                 | Subcommand::Bench { .. }
1353                 | Subcommand::Dist { .. }
1354                 | Subcommand::Install { .. } => {
1355                     assert_eq!(
1356                         config.stage, 2,
1357                         "x.py should be run with `--stage 2` on CI, but was run with `--stage {}`",
1358                         config.stage,
1359                     );
1360                 }
1361                 Subcommand::Clean { .. }
1362                 | Subcommand::Check { .. }
1363                 | Subcommand::Clippy { .. }
1364                 | Subcommand::Fix { .. }
1365                 | Subcommand::Run { .. }
1366                 | Subcommand::Setup { .. }
1367                 | Subcommand::Format { .. } => {}
1368             }
1369         }
1370
1371         config
1372     }
1373
1374     /// A git invocation which runs inside the source directory.
1375     ///
1376     /// Use this rather than `Command::new("git")` in order to support out-of-tree builds.
1377     pub(crate) fn git(&self) -> Command {
1378         let mut git = Command::new("git");
1379         git.current_dir(&self.src);
1380         git
1381     }
1382
1383     pub(crate) fn artifact_channel(&self, builder: &Builder<'_>, commit: &str) -> String {
1384         if builder.rust_info.is_managed_git_subrepository() {
1385             let mut channel = self.git();
1386             channel.arg("show").arg(format!("{}:src/ci/channel", commit));
1387             let channel = output(&mut channel);
1388             channel.trim().to_owned()
1389         } else if let Ok(channel) = fs::read_to_string(builder.src.join("src/ci/channel")) {
1390             channel.trim().to_owned()
1391         } else {
1392             let src = builder.src.display();
1393             eprintln!("error: failed to determine artifact channel");
1394             eprintln!(
1395                 "help: either use git or ensure that {src}/src/ci/channel contains the name of the channel to use"
1396             );
1397             panic!();
1398         }
1399     }
1400
1401     /// Try to find the relative path of `bindir`, otherwise return it in full.
1402     pub fn bindir_relative(&self) -> &Path {
1403         let bindir = &self.bindir;
1404         if bindir.is_absolute() {
1405             // Try to make it relative to the prefix.
1406             if let Some(prefix) = &self.prefix {
1407                 if let Ok(stripped) = bindir.strip_prefix(prefix) {
1408                     return stripped;
1409                 }
1410             }
1411         }
1412         bindir
1413     }
1414
1415     /// Try to find the relative path of `libdir`.
1416     pub fn libdir_relative(&self) -> Option<&Path> {
1417         let libdir = self.libdir.as_ref()?;
1418         if libdir.is_relative() {
1419             Some(libdir)
1420         } else {
1421             // Try to make it relative to the prefix.
1422             libdir.strip_prefix(self.prefix.as_ref()?).ok()
1423         }
1424     }
1425
1426     /// The absolute path to the downloaded LLVM artifacts.
1427     pub(crate) fn ci_llvm_root(&self) -> PathBuf {
1428         assert!(self.llvm_from_ci);
1429         self.out.join(&*self.build.triple).join("ci-llvm")
1430     }
1431
1432     /// Determine whether llvm should be linked dynamically.
1433     ///
1434     /// If `false`, llvm should be linked statically.
1435     /// This is computed on demand since LLVM might have to first be downloaded from CI.
1436     pub(crate) fn llvm_link_shared(builder: &Builder<'_>) -> bool {
1437         let mut opt = builder.config.llvm_link_shared.get();
1438         if opt.is_none() && builder.config.dry_run {
1439             // just assume static for now - dynamic linking isn't supported on all platforms
1440             return false;
1441         }
1442
1443         let llvm_link_shared = *opt.get_or_insert_with(|| {
1444             if builder.config.llvm_from_ci {
1445                 crate::native::maybe_download_ci_llvm(builder);
1446                 let ci_llvm = builder.config.ci_llvm_root();
1447                 let link_type = t!(
1448                     std::fs::read_to_string(ci_llvm.join("link-type.txt")),
1449                     format!("CI llvm missing: {}", ci_llvm.display())
1450                 );
1451                 link_type == "dynamic"
1452             } else {
1453                 // unclear how thought-through this default is, but it maintains compatibility with
1454                 // previous behavior
1455                 false
1456             }
1457         });
1458         builder.config.llvm_link_shared.set(opt);
1459         llvm_link_shared
1460     }
1461
1462     /// Return whether we will use a downloaded, pre-compiled version of rustc, or just build from source.
1463     pub(crate) fn download_rustc(builder: &Builder<'_>) -> bool {
1464         static DOWNLOAD_RUSTC: OnceCell<bool> = OnceCell::new();
1465         if builder.config.dry_run && DOWNLOAD_RUSTC.get().is_none() {
1466             // avoid trying to actually download the commit
1467             return false;
1468         }
1469
1470         *DOWNLOAD_RUSTC.get_or_init(|| match &builder.config.download_rustc_commit {
1471             None => false,
1472             Some(commit) => {
1473                 download_ci_rustc(builder, commit);
1474                 true
1475             }
1476         })
1477     }
1478
1479     pub(crate) fn initial_rustfmt(builder: &Builder<'_>) -> Option<PathBuf> {
1480         match &mut *builder.config.initial_rustfmt.borrow_mut() {
1481             RustfmtState::SystemToolchain(p) | RustfmtState::Downloaded(p) => Some(p.clone()),
1482             RustfmtState::Unavailable => None,
1483             r @ RustfmtState::LazyEvaluated => {
1484                 if builder.config.dry_run {
1485                     return Some(PathBuf::new());
1486                 }
1487                 let path = maybe_download_rustfmt(builder);
1488                 *r = if let Some(p) = &path {
1489                     RustfmtState::Downloaded(p.clone())
1490                 } else {
1491                     RustfmtState::Unavailable
1492                 };
1493                 path
1494             }
1495         }
1496     }
1497
1498     pub fn verbose(&self) -> bool {
1499         self.verbose > 0
1500     }
1501
1502     pub fn sanitizers_enabled(&self, target: TargetSelection) -> bool {
1503         self.target_config.get(&target).map(|t| t.sanitizers).flatten().unwrap_or(self.sanitizers)
1504     }
1505
1506     pub fn any_sanitizers_enabled(&self) -> bool {
1507         self.target_config.values().any(|t| t.sanitizers == Some(true)) || self.sanitizers
1508     }
1509
1510     pub fn profiler_enabled(&self, target: TargetSelection) -> bool {
1511         self.target_config.get(&target).map(|t| t.profiler).flatten().unwrap_or(self.profiler)
1512     }
1513
1514     pub fn any_profiler_enabled(&self) -> bool {
1515         self.target_config.values().any(|t| t.profiler == Some(true)) || self.profiler
1516     }
1517
1518     pub fn llvm_enabled(&self) -> bool {
1519         self.rust_codegen_backends.contains(&INTERNER.intern_str("llvm"))
1520     }
1521
1522     pub fn llvm_libunwind(&self, target: TargetSelection) -> LlvmLibunwind {
1523         self.target_config
1524             .get(&target)
1525             .and_then(|t| t.llvm_libunwind)
1526             .or(self.llvm_libunwind_default)
1527             .unwrap_or(if target.contains("fuchsia") {
1528                 LlvmLibunwind::InTree
1529             } else {
1530                 LlvmLibunwind::No
1531             })
1532     }
1533
1534     pub fn submodules(&self, rust_info: &GitInfo) -> bool {
1535         self.submodules.unwrap_or(rust_info.is_managed_git_subrepository())
1536     }
1537 }
1538
1539 fn set<T>(field: &mut T, val: Option<T>) {
1540     if let Some(v) = val {
1541         *field = v;
1542     }
1543 }
1544
1545 fn threads_from_config(v: u32) -> u32 {
1546     match v {
1547         0 => std::thread::available_parallelism().map_or(1, std::num::NonZeroUsize::get) as u32,
1548         n => n,
1549     }
1550 }
1551
1552 /// Returns the commit to download, or `None` if we shouldn't download CI artifacts.
1553 fn download_ci_rustc_commit(
1554     config: &Config,
1555     download_rustc: Option<StringOrBool>,
1556 ) -> Option<String> {
1557     // If `download-rustc` is not set, default to rebuilding.
1558     let if_unchanged = match download_rustc {
1559         None | Some(StringOrBool::Bool(false)) => return None,
1560         Some(StringOrBool::Bool(true)) => false,
1561         Some(StringOrBool::String(s)) if s == "if-unchanged" => true,
1562         Some(StringOrBool::String(other)) => {
1563             panic!("unrecognized option for download-rustc: {}", other)
1564         }
1565     };
1566
1567     // Handle running from a directory other than the top level
1568     let top_level = output(config.git().args(&["rev-parse", "--show-toplevel"]));
1569     let top_level = top_level.trim_end();
1570     let compiler = format!("{top_level}/compiler/");
1571     let library = format!("{top_level}/library/");
1572
1573     // Look for a version to compare to based on the current commit.
1574     // Only commits merged by bors will have CI artifacts.
1575     let merge_base = output(
1576         config
1577             .git()
1578             .arg("rev-list")
1579             .arg(format!("--author={}", config.stage0_metadata.config.git_merge_commit_email))
1580             .args(&["-n1", "--first-parent", "HEAD"]),
1581     );
1582     let commit = merge_base.trim_end();
1583     if commit.is_empty() {
1584         println!("error: could not find commit hash for downloading rustc");
1585         println!("help: maybe your repository history is too shallow?");
1586         println!("help: consider disabling `download-rustc`");
1587         println!("help: or fetch enough history to include one upstream commit");
1588         crate::detail_exit(1);
1589     }
1590
1591     // Warn if there were changes to the compiler or standard library since the ancestor commit.
1592     let has_changes = !t!(config
1593         .git()
1594         .args(&["diff-index", "--quiet", &commit, "--", &compiler, &library])
1595         .status())
1596     .success();
1597     if has_changes {
1598         if if_unchanged {
1599             if config.verbose > 0 {
1600                 println!(
1601                     "warning: saw changes to compiler/ or library/ since {commit}; \
1602                           ignoring `download-rustc`"
1603                 );
1604             }
1605             return None;
1606         }
1607         println!(
1608             "warning: `download-rustc` is enabled, but there are changes to \
1609                   compiler/ or library/"
1610         );
1611     }
1612
1613     Some(commit.to_string())
1614 }
1615
1616 fn maybe_download_rustfmt(builder: &Builder<'_>) -> Option<PathBuf> {
1617     let RustfmtMetadata { date, version } = builder.config.stage0_metadata.rustfmt.as_ref()?;
1618     let channel = format!("{version}-{date}");
1619
1620     let host = builder.config.build;
1621     let rustfmt_path = builder.config.initial_rustc.with_file_name(exe("rustfmt", host));
1622     let bin_root = builder.config.out.join(host.triple).join("stage0");
1623     let rustfmt_stamp = bin_root.join(".rustfmt-stamp");
1624     if rustfmt_path.exists() && !program_out_of_date(&rustfmt_stamp, &channel) {
1625         return Some(rustfmt_path);
1626     }
1627
1628     let filename = format!("rustfmt-{version}-{build}.tar.xz", build = host.triple);
1629     download_component(builder, DownloadSource::Dist, filename, "rustfmt-preview", &date, "stage0");
1630
1631     builder.fix_bin_or_dylib(&bin_root.join("bin").join("rustfmt"));
1632     builder.fix_bin_or_dylib(&bin_root.join("bin").join("cargo-fmt"));
1633
1634     builder.create(&rustfmt_stamp, &channel);
1635     Some(rustfmt_path)
1636 }
1637
1638 fn download_ci_rustc(builder: &Builder<'_>, commit: &str) {
1639     builder.verbose(&format!("using downloaded stage2 artifacts from CI (commit {commit})"));
1640     let channel = builder.config.artifact_channel(builder, commit);
1641     let host = builder.config.build.triple;
1642     let bin_root = builder.out.join(host).join("ci-rustc");
1643     let rustc_stamp = bin_root.join(".rustc-stamp");
1644
1645     if !bin_root.join("bin").join("rustc").exists() || program_out_of_date(&rustc_stamp, commit) {
1646         if bin_root.exists() {
1647             t!(fs::remove_dir_all(&bin_root));
1648         }
1649         let filename = format!("rust-std-{channel}-{host}.tar.xz");
1650         let pattern = format!("rust-std-{host}");
1651         download_ci_component(builder, filename, &pattern, commit);
1652         let filename = format!("rustc-{channel}-{host}.tar.xz");
1653         download_ci_component(builder, filename, "rustc", commit);
1654         // download-rustc doesn't need its own cargo, it can just use beta's.
1655         let filename = format!("rustc-dev-{channel}-{host}.tar.xz");
1656         download_ci_component(builder, filename, "rustc-dev", commit);
1657
1658         builder.fix_bin_or_dylib(&bin_root.join("bin").join("rustc"));
1659         builder.fix_bin_or_dylib(&bin_root.join("bin").join("rustdoc"));
1660         let lib_dir = bin_root.join("lib");
1661         for lib in t!(fs::read_dir(&lib_dir), lib_dir.display().to_string()) {
1662             let lib = t!(lib);
1663             if lib.path().extension() == Some(OsStr::new("so")) {
1664                 builder.fix_bin_or_dylib(&lib.path());
1665             }
1666         }
1667         t!(fs::write(rustc_stamp, commit));
1668     }
1669 }
1670
1671 pub(crate) enum DownloadSource {
1672     CI,
1673     Dist,
1674 }
1675
1676 /// Download a single component of a CI-built toolchain (not necessarily a published nightly).
1677 // NOTE: intentionally takes an owned string to avoid downloading multiple times by accident
1678 fn download_ci_component(builder: &Builder<'_>, filename: String, prefix: &str, commit: &str) {
1679     download_component(builder, DownloadSource::CI, filename, prefix, commit, "ci-rustc")
1680 }
1681
1682 fn download_component(
1683     builder: &Builder<'_>,
1684     mode: DownloadSource,
1685     filename: String,
1686     prefix: &str,
1687     key: &str,
1688     destination: &str,
1689 ) {
1690     let cache_dst = builder.out.join("cache");
1691     let cache_dir = cache_dst.join(key);
1692     if !cache_dir.exists() {
1693         t!(fs::create_dir_all(&cache_dir));
1694     }
1695
1696     let bin_root = builder.out.join(builder.config.build.triple).join(destination);
1697     let tarball = cache_dir.join(&filename);
1698     let (base_url, url, should_verify) = match mode {
1699         DownloadSource::CI => (
1700             builder.config.stage0_metadata.config.artifacts_server.clone(),
1701             format!("{key}/{filename}"),
1702             false,
1703         ),
1704         DownloadSource::Dist => {
1705             let dist_server = env::var("RUSTUP_DIST_SERVER")
1706                 .unwrap_or(builder.config.stage0_metadata.config.dist_server.to_string());
1707             // NOTE: make `dist` part of the URL because that's how it's stored in src/stage0.json
1708             (dist_server, format!("dist/{key}/{filename}"), true)
1709         }
1710     };
1711
1712     // For the beta compiler, put special effort into ensuring the checksums are valid.
1713     // FIXME: maybe we should do this for download-rustc as well? but it would be a pain to update
1714     // this on each and every nightly ...
1715     let checksum = if should_verify {
1716         let error = format!(
1717             "src/stage0.json doesn't contain a checksum for {url}. \
1718             Pre-built artifacts might not be available for this \
1719             target at this time, see https://doc.rust-lang.org/nightly\
1720             /rustc/platform-support.html for more information."
1721         );
1722         let sha256 = builder.config.stage0_metadata.checksums_sha256.get(&url).expect(&error);
1723         if tarball.exists() {
1724             if builder.verify(&tarball, sha256) {
1725                 builder.unpack(&tarball, &bin_root, prefix);
1726                 return;
1727             } else {
1728                 builder.verbose(&format!(
1729                     "ignoring cached file {} due to failed verification",
1730                     tarball.display()
1731                 ));
1732                 builder.remove(&tarball);
1733             }
1734         }
1735         Some(sha256)
1736     } else if tarball.exists() {
1737         builder.unpack(&tarball, &bin_root, prefix);
1738         return;
1739     } else {
1740         None
1741     };
1742
1743     builder.download_component(&format!("{base_url}/{url}"), &tarball, "");
1744     if let Some(sha256) = checksum {
1745         if !builder.verify(&tarball, sha256) {
1746             panic!("failed to verify {}", tarball.display());
1747         }
1748     }
1749
1750     builder.unpack(&tarball, &bin_root, prefix);
1751 }