src/librustc/session/mod.rs

   1 // Copyright 2012-2013 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 pub use self::code_stats::{CodeStats, DataTypeKind, FieldInfo};
  12 pub use self::code_stats::{SizeKind, TypeSizeInfo, VariantInfo};
  13
  14 use hir::def_id::CrateNum;
  15 use ich::Fingerprint;
  16
  17 use lint;
  18 use middle::allocator::AllocatorKind;
  19 use middle::dependency_format;
  20 use session::search_paths::PathKind;
  21 use session::config::{BorrowckMode, DebugInfoLevel, OutputType};
  22 use ty::tls;
  23 use util::nodemap::{FxHashMap, FxHashSet};
  24 use util::common::{duration_to_secs_str, ErrorReported};
  25
  26 use syntax::ast::NodeId;
  27 use errors::{self, DiagnosticBuilder, DiagnosticId};
  28 use errors::emitter::{Emitter, EmitterWriter};
  29 use syntax::json::JsonEmitter;
  30 use syntax::feature_gate;
  31 use syntax::parse;
  32 use syntax::parse::ParseSess;
  33 use syntax::{ast, codemap};
  34 use syntax::feature_gate::AttributeType;
  35 use syntax_pos::{Span, MultiSpan};
  36
  37 use rustc_back::{LinkerFlavor, PanicStrategy};
  38 use rustc_back::target::Target;
  39 use rustc_data_structures::flock;
  40 use jobserver::Client;
  41
  42 use std::cell::{self, Cell, RefCell};
  43 use std::collections::HashMap;
  44 use std::env;
  45 use std::fmt;
  46 use std::io::Write;
  47 use std::path::{Path, PathBuf};
  48 use std::rc::Rc;
  49 use std::sync::{Once, ONCE_INIT};
  50 use std::time::Duration;
  51
  52 mod code_stats;
  53 pub mod config;
  54 pub mod filesearch;
  55 pub mod search_paths;
  56
  57 /// Represents the data associated with a compilation
  58 /// session for a single crate.
  59 pub struct Session {
  60     pub target: config::Config,
  61     pub host: Target,
  62     pub opts: config::Options,
  63     pub parse_sess: ParseSess,
  64     /// For a library crate, this is always none
  65     pub entry_fn: RefCell<Option<(NodeId, Span)>>,
  66     pub entry_type: Cell<Option<config::EntryFnType>>,
  67     pub plugin_registrar_fn: Cell<Option<ast::NodeId>>,
  68     pub derive_registrar_fn: Cell<Option<ast::NodeId>>,
  69     pub default_sysroot: Option<PathBuf>,
  70     /// The name of the root source file of the crate, in the local file system.
  71     /// `None` means that there is no source file.
  72     pub local_crate_source_file: Option<PathBuf>,
  73     /// The directory the compiler has been executed in plus a flag indicating
  74     /// if the value stored here has been affected by path remapping.
  75     pub working_dir: (PathBuf, bool),
  76     pub lint_store: RefCell<lint::LintStore>,
  77     pub buffered_lints: RefCell<Option<lint::LintBuffer>>,
  78     /// Set of (DiagnosticId, Option<Span>, message) tuples tracking
  79     /// (sub)diagnostics that have been set once, but should not be set again,
  80     /// in order to avoid redundantly verbose output (Issue #24690, #44953).
  81     pub one_time_diagnostics: RefCell<FxHashSet<(DiagnosticMessageId, Option<Span>, String)>>,
  82     pub plugin_llvm_passes: RefCell<Vec<String>>,
  83     pub plugin_attributes: RefCell<Vec<(String, AttributeType)>>,
  84     pub crate_types: RefCell<Vec<config::CrateType>>,
  85     pub dependency_formats: RefCell<dependency_format::Dependencies>,
  86         /// The crate_disambiguator is constructed out of all the `-C metadata`
  87     /// arguments passed to the compiler. Its value together with the crate-name
  88     /// forms a unique global identifier for the crate. It is used to allow
  89     /// multiple crates with the same name to coexist. See the
  90     /// trans::back::symbol_names module for more information.
  91     pub crate_disambiguator: RefCell<Option<CrateDisambiguator>>,
  92     pub features: RefCell<feature_gate::Features>,
  93
  94     /// The maximum recursion limit for potentially infinitely recursive
  95     /// operations such as auto-dereference and monomorphization.
  96     pub recursion_limit: Cell<usize>,
  97
  98     /// The maximum length of types during monomorphization.
  99     pub type_length_limit: Cell<usize>,
 100
 101     /// The metadata::creader module may inject an allocator/panic_runtime
 102     /// dependency if it didn't already find one, and this tracks what was
 103     /// injected.
 104     pub injected_allocator: Cell<Option<CrateNum>>,
 105     pub allocator_kind: Cell<Option<AllocatorKind>>,
 106     pub injected_panic_runtime: Cell<Option<CrateNum>>,
 107
 108     /// Map from imported macro spans (which consist of
 109     /// the localized span for the macro body) to the
 110     /// macro name and definition span in the source crate.
 111     pub imported_macro_spans: RefCell<HashMap<Span, (String, Span)>>,
 112
 113     incr_comp_session: RefCell<IncrCompSession>,
 114
 115     /// Some measurements that are being gathered during compilation.
 116     pub perf_stats: PerfStats,
 117
 118     /// Data about code being compiled, gathered during compilation.
 119     pub code_stats: RefCell<CodeStats>,
 120
 121     next_node_id: Cell<ast::NodeId>,
 122
 123     /// If -zfuel=crate=n is specified, Some(crate).
 124     optimization_fuel_crate: Option<String>,
 125     /// If -zfuel=crate=n is specified, initially set to n. Otherwise 0.
 126     optimization_fuel_limit: Cell<u64>,
 127     /// We're rejecting all further optimizations.
 128     out_of_fuel: Cell<bool>,
 129
 130     // The next two are public because the driver needs to read them.
 131
 132     /// If -zprint-fuel=crate, Some(crate).
 133     pub print_fuel_crate: Option<String>,
 134     /// Always set to zero and incremented so that we can print fuel expended by a crate.
 135     pub print_fuel: Cell<u64>,
 136
 137     /// Loaded up early on in the initialization of this `Session` to avoid
 138     /// false positives about a job server in our environment.
 139     pub jobserver_from_env: Option<Client>,
 140
 141     /// Metadata about the allocators for the current crate being compiled
 142     pub has_global_allocator: Cell<bool>,
 143 }
 144
 145 pub struct PerfStats {
 146     /// The accumulated time needed for computing the SVH of the crate
 147     pub svh_time: Cell<Duration>,
 148     /// The accumulated time spent on computing incr. comp. hashes
 149     pub incr_comp_hashes_time: Cell<Duration>,
 150     /// The number of incr. comp. hash computations performed
 151     pub incr_comp_hashes_count: Cell<u64>,
 152     /// The number of bytes hashed when computing ICH values
 153     pub incr_comp_bytes_hashed: Cell<u64>,
 154     /// The accumulated time spent on computing symbol hashes
 155     pub symbol_hash_time: Cell<Duration>,
 156     /// The accumulated time spent decoding def path tables from metadata
 157     pub decode_def_path_tables_time: Cell<Duration>,
 158 }
 159
 160 /// Enum to support dispatch of one-time diagnostics (in Session.diag_once)
 161 enum DiagnosticBuilderMethod {
 162     Note,
 163     SpanNote,
 164     SpanSuggestion(String), // suggestion
 165     // add more variants as needed to support one-time diagnostics
 166 }
 167
 168 /// Diagnostic message ID—used by `Session.one_time_diagnostics` to avoid
 169 /// emitting the same message more than once
 170 #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
 171 pub enum DiagnosticMessageId {
 172     ErrorId(u16), // EXXXX error code as integer
 173     LintId(lint::LintId),
 174     StabilityId(u32) // issue number
 175 }
 176
 177 impl From<&'static lint::Lint> for DiagnosticMessageId {
 178     fn from(lint: &'static lint::Lint) -> Self {
 179         DiagnosticMessageId::LintId(lint::LintId::of(lint))
 180     }
 181 }
 182
 183 impl Session {
 184     pub fn local_crate_disambiguator(&self) -> CrateDisambiguator {
 185         match *self.crate_disambiguator.borrow() {
 186             Some(value) => value,
 187             None => bug!("accessing disambiguator before initialization"),
 188         }
 189     }
 190     pub fn struct_span_warn<'a, S: Into<MultiSpan>>(&'a self,
 191                                                     sp: S,
 192                                                     msg: &str)
 193                                                     -> DiagnosticBuilder<'a> {
 194         self.diagnostic().struct_span_warn(sp, msg)
 195     }
 196     pub fn struct_span_warn_with_code<'a, S: Into<MultiSpan>>(&'a self,
 197                                                               sp: S,
 198                                                               msg: &str,
 199                                                               code: DiagnosticId)
 200                                                               -> DiagnosticBuilder<'a> {
 201         self.diagnostic().struct_span_warn_with_code(sp, msg, code)
 202     }
 203     pub fn struct_warn<'a>(&'a self, msg: &str) -> DiagnosticBuilder<'a>  {
 204         self.diagnostic().struct_warn(msg)
 205     }
 206     pub fn struct_span_err<'a, S: Into<MultiSpan>>(&'a self,
 207                                                    sp: S,
 208                                                    msg: &str)
 209                                                    -> DiagnosticBuilder<'a> {
 210         self.diagnostic().struct_span_err(sp, msg)
 211     }
 212     pub fn struct_span_err_with_code<'a, S: Into<MultiSpan>>(&'a self,
 213                                                              sp: S,
 214                                                              msg: &str,
 215                                                              code: DiagnosticId)
 216                                                              -> DiagnosticBuilder<'a> {
 217         self.diagnostic().struct_span_err_with_code(sp, msg, code)
 218     }
 219     // FIXME: This method should be removed (every error should have an associated error code).
 220     pub fn struct_err<'a>(&'a self, msg: &str) -> DiagnosticBuilder<'a> {
 221         self.diagnostic().struct_err(msg)
 222     }
 223     pub fn struct_err_with_code<'a>(
 224         &'a self,
 225         msg: &str,
 226         code: DiagnosticId,
 227     ) -> DiagnosticBuilder<'a> {
 228         self.diagnostic().struct_err_with_code(msg, code)
 229     }
 230     pub fn struct_span_fatal<'a, S: Into<MultiSpan>>(&'a self,
 231                                                      sp: S,
 232                                                      msg: &str)
 233                                                      -> DiagnosticBuilder<'a> {
 234         self.diagnostic().struct_span_fatal(sp, msg)
 235     }
 236     pub fn struct_span_fatal_with_code<'a, S: Into<MultiSpan>>(&'a self,
 237                                                                sp: S,
 238                                                                msg: &str,
 239                                                                code: DiagnosticId)
 240                                                                -> DiagnosticBuilder<'a> {
 241         self.diagnostic().struct_span_fatal_with_code(sp, msg, code)
 242     }
 243     pub fn struct_fatal<'a>(&'a self, msg: &str) -> DiagnosticBuilder<'a>  {
 244         self.diagnostic().struct_fatal(msg)
 245     }
 246
 247     pub fn span_fatal<S: Into<MultiSpan>>(&self, sp: S, msg: &str) -> ! {
 248         panic!(self.diagnostic().span_fatal(sp, msg))
 249     }
 250     pub fn span_fatal_with_code<S: Into<MultiSpan>>(
 251         &self,
 252         sp: S,
 253         msg: &str,
 254         code: DiagnosticId,
 255     ) -> ! {
 256         panic!(self.diagnostic().span_fatal_with_code(sp, msg, code))
 257     }
 258     pub fn fatal(&self, msg: &str) -> ! {
 259         panic!(self.diagnostic().fatal(msg))
 260     }
 261     pub fn span_err_or_warn<S: Into<MultiSpan>>(&self, is_warning: bool, sp: S, msg: &str) {
 262         if is_warning {
 263             self.span_warn(sp, msg);
 264         } else {
 265             self.span_err(sp, msg);
 266         }
 267     }
 268     pub fn span_err<S: Into<MultiSpan>>(&self, sp: S, msg: &str) {
 269         self.diagnostic().span_err(sp, msg)
 270     }
 271     pub fn span_err_with_code<S: Into<MultiSpan>>(&self, sp: S, msg: &str, code: DiagnosticId) {
 272         self.diagnostic().span_err_with_code(sp, &msg, code)
 273     }
 274     pub fn err(&self, msg: &str) {
 275         self.diagnostic().err(msg)
 276     }
 277     pub fn err_count(&self) -> usize {
 278         self.diagnostic().err_count()
 279     }
 280     pub fn has_errors(&self) -> bool {
 281         self.diagnostic().has_errors()
 282     }
 283     pub fn abort_if_errors(&self) {
 284         self.diagnostic().abort_if_errors();
 285     }
 286     pub fn compile_status(&self) -> Result<(), CompileIncomplete> {
 287         compile_result_from_err_count(self.err_count())
 288     }
 289     pub fn track_errors<F, T>(&self, f: F) -> Result<T, ErrorReported>
 290         where F: FnOnce() -> T
 291     {
 292         let old_count = self.err_count();
 293         let result = f();
 294         let errors = self.err_count() - old_count;
 295         if errors == 0 {
 296             Ok(result)
 297         } else {
 298             Err(ErrorReported)
 299         }
 300     }
 301     pub fn span_warn<S: Into<MultiSpan>>(&self, sp: S, msg: &str) {
 302         self.diagnostic().span_warn(sp, msg)
 303     }
 304     pub fn span_warn_with_code<S: Into<MultiSpan>>(&self, sp: S, msg: &str, code: DiagnosticId) {
 305         self.diagnostic().span_warn_with_code(sp, msg, code)
 306     }
 307     pub fn warn(&self, msg: &str) {
 308         self.diagnostic().warn(msg)
 309     }
 310     pub fn opt_span_warn<S: Into<MultiSpan>>(&self, opt_sp: Option<S>, msg: &str) {
 311         match opt_sp {
 312             Some(sp) => self.span_warn(sp, msg),
 313             None => self.warn(msg),
 314         }
 315     }
 316     /// Delay a span_bug() call until abort_if_errors()
 317     pub fn delay_span_bug<S: Into<MultiSpan>>(&self, sp: S, msg: &str) {
 318         self.diagnostic().delay_span_bug(sp, msg)
 319     }
 320     pub fn note_without_error(&self, msg: &str) {
 321         self.diagnostic().note_without_error(msg)
 322     }
 323     pub fn span_note_without_error<S: Into<MultiSpan>>(&self, sp: S, msg: &str) {
 324         self.diagnostic().span_note_without_error(sp, msg)
 325     }
 326     pub fn span_unimpl<S: Into<MultiSpan>>(&self, sp: S, msg: &str) -> ! {
 327         self.diagnostic().span_unimpl(sp, msg)
 328     }
 329     pub fn unimpl(&self, msg: &str) -> ! {
 330         self.diagnostic().unimpl(msg)
 331     }
 332
 333     pub fn buffer_lint<S: Into<MultiSpan>>(&self,
 334                                            lint: &'static lint::Lint,
 335                                            id: ast::NodeId,
 336                                            sp: S,
 337                                            msg: &str) {
 338         match *self.buffered_lints.borrow_mut() {
 339             Some(ref mut buffer) => buffer.add_lint(lint, id, sp.into(), msg),
 340             None => bug!("can't buffer lints after HIR lowering"),
 341         }
 342     }
 343
 344     pub fn reserve_node_ids(&self, count: usize) -> ast::NodeId {
 345         let id = self.next_node_id.get();
 346
 347         match id.as_usize().checked_add(count) {
 348             Some(next) => {
 349                 self.next_node_id.set(ast::NodeId::new(next));
 350             }
 351             None => bug!("Input too large, ran out of node ids!")
 352         }
 353
 354         id
 355     }
 356     pub fn next_node_id(&self) -> NodeId {
 357         self.reserve_node_ids(1)
 358     }
 359     pub fn diagnostic<'a>(&'a self) -> &'a errors::Handler {
 360         &self.parse_sess.span_diagnostic
 361     }
 362
 363     /// Analogous to calling methods on the given `DiagnosticBuilder`, but
 364     /// deduplicates on lint ID, span (if any), and message for this `Session`
 365     fn diag_once<'a, 'b>(&'a self,
 366                          diag_builder: &'b mut DiagnosticBuilder<'a>,
 367                          method: DiagnosticBuilderMethod,
 368                          msg_id: DiagnosticMessageId,
 369                          message: &str,
 370                          span_maybe: Option<Span>) {
 371
 372         let id_span_message = (msg_id, span_maybe, message.to_owned());
 373         let fresh = self.one_time_diagnostics.borrow_mut().insert(id_span_message);
 374         if fresh {
 375             match method {
 376                 DiagnosticBuilderMethod::Note => {
 377                     diag_builder.note(message);
 378                 },
 379                 DiagnosticBuilderMethod::SpanNote => {
 380                     let span = span_maybe.expect("span_note needs a span");
 381                     diag_builder.span_note(span, message);
 382                 },
 383                 DiagnosticBuilderMethod::SpanSuggestion(suggestion) => {
 384                     let span = span_maybe.expect("span_suggestion needs a span");
 385                     diag_builder.span_suggestion(span, message, suggestion);
 386                 }
 387             }
 388         }
 389     }
 390
 391     pub fn diag_span_note_once<'a, 'b>(&'a self,
 392                                        diag_builder: &'b mut DiagnosticBuilder<'a>,
 393                                        msg_id: DiagnosticMessageId, span: Span, message: &str) {
 394         self.diag_once(diag_builder, DiagnosticBuilderMethod::SpanNote,
 395                        msg_id, message, Some(span));
 396     }
 397
 398     pub fn diag_note_once<'a, 'b>(&'a self,
 399                                   diag_builder: &'b mut DiagnosticBuilder<'a>,
 400                                   msg_id: DiagnosticMessageId, message: &str) {
 401         self.diag_once(diag_builder, DiagnosticBuilderMethod::Note, msg_id, message, None);
 402     }
 403
 404     pub fn diag_span_suggestion_once<'a, 'b>(&'a self,
 405                                              diag_builder: &'b mut DiagnosticBuilder<'a>,
 406                                              msg_id: DiagnosticMessageId,
 407                                              span: Span,
 408                                              message: &str,
 409                                              suggestion: String) {
 410         self.diag_once(diag_builder, DiagnosticBuilderMethod::SpanSuggestion(suggestion),
 411                        msg_id, message, Some(span));
 412     }
 413
 414     pub fn codemap<'a>(&'a self) -> &'a codemap::CodeMap {
 415         self.parse_sess.codemap()
 416     }
 417     pub fn verbose(&self) -> bool { self.opts.debugging_opts.verbose }
 418     pub fn time_passes(&self) -> bool { self.opts.debugging_opts.time_passes }
 419     pub fn profile_queries(&self) -> bool {
 420         self.opts.debugging_opts.profile_queries ||
 421             self.opts.debugging_opts.profile_queries_and_keys
 422     }
 423     pub fn profile_queries_and_keys(&self) -> bool {
 424         self.opts.debugging_opts.profile_queries_and_keys
 425     }
 426     pub fn count_llvm_insns(&self) -> bool {
 427         self.opts.debugging_opts.count_llvm_insns
 428     }
 429     pub fn time_llvm_passes(&self) -> bool {
 430         self.opts.debugging_opts.time_llvm_passes
 431     }
 432     pub fn trans_stats(&self) -> bool { self.opts.debugging_opts.trans_stats }
 433     pub fn meta_stats(&self) -> bool { self.opts.debugging_opts.meta_stats }
 434     pub fn asm_comments(&self) -> bool { self.opts.debugging_opts.asm_comments }
 435     pub fn no_verify(&self) -> bool { self.opts.debugging_opts.no_verify }
 436     pub fn borrowck_stats(&self) -> bool { self.opts.debugging_opts.borrowck_stats }
 437     pub fn print_llvm_passes(&self) -> bool {
 438         self.opts.debugging_opts.print_llvm_passes
 439     }
 440
 441     /// If true, we should use NLL-style region checking instead of
 442     /// lexical style.
 443     pub fn nll(&self) -> bool {
 444         self.features.borrow().nll || self.opts.debugging_opts.nll
 445     }
 446
 447     /// If true, we should use the MIR-based borrowck (we may *also* use
 448     /// the AST-based borrowck).
 449     pub fn use_mir(&self) -> bool {
 450         self.borrowck_mode().use_mir()
 451     }
 452
 453     /// If true, we should gather causal information during NLL
 454     /// checking. This will eventually be the normal thing, but right
 455     /// now it is too unoptimized.
 456     pub fn nll_dump_cause(&self) -> bool {
 457         self.opts.debugging_opts.nll_dump_cause
 458     }
 459
 460     /// If true, we should enable two-phase borrows checks. This is
 461     /// done with either `-Ztwo-phase-borrows` or with
 462     /// `#![feature(nll)]`.
 463     pub fn two_phase_borrows(&self) -> bool {
 464         self.features.borrow().nll || self.opts.debugging_opts.two_phase_borrows
 465     }
 466
 467     /// What mode(s) of borrowck should we run? AST? MIR? both?
 468     /// (Also considers the `#![feature(nll)]` setting.)
 469     pub fn borrowck_mode(&self) -> BorrowckMode {
 470         match self.opts.borrowck_mode {
 471             mode @ BorrowckMode::Mir |
 472             mode @ BorrowckMode::Compare => mode,
 473
 474             mode @ BorrowckMode::Ast => {
 475                 if self.nll() {
 476                     BorrowckMode::Mir
 477                 } else {
 478                     mode
 479                 }
 480             }
 481
 482         }
 483     }
 484
 485     /// Should we emit EndRegion MIR statements? These are consumed by
 486     /// MIR borrowck, but not when NLL is used. They are also consumed
 487     /// by the validation stuff.
 488     pub fn emit_end_regions(&self) -> bool {
 489         // FIXME(#46875) -- we should not emit end regions when NLL is enabled,
 490         // but for now we can't stop doing so because it causes false positives
 491         self.opts.debugging_opts.emit_end_regions ||
 492             self.opts.debugging_opts.mir_emit_validate > 0 ||
 493             self.use_mir()
 494     }
 495
 496     pub fn lto(&self) -> bool {
 497         self.opts.cg.lto || self.target.target.options.requires_lto
 498     }
 499     /// Returns the panic strategy for this compile session. If the user explicitly selected one
 500     /// using '-C panic', use that, otherwise use the panic strategy defined by the target.
 501     pub fn panic_strategy(&self) -> PanicStrategy {
 502         self.opts.cg.panic.unwrap_or(self.target.target.options.panic_strategy)
 503     }
 504     pub fn linker_flavor(&self) -> LinkerFlavor {
 505         self.opts.debugging_opts.linker_flavor.unwrap_or(self.target.target.linker_flavor)
 506     }
 507
 508     pub fn fewer_names(&self) -> bool {
 509         let more_names = self.opts.output_types.contains_key(&OutputType::LlvmAssembly) ||
 510                          self.opts.output_types.contains_key(&OutputType::Bitcode);
 511         self.opts.debugging_opts.fewer_names || !more_names
 512     }
 513
 514     pub fn no_landing_pads(&self) -> bool {
 515         self.opts.debugging_opts.no_landing_pads || self.panic_strategy() == PanicStrategy::Abort
 516     }
 517     pub fn unstable_options(&self) -> bool {
 518         self.opts.debugging_opts.unstable_options
 519     }
 520     pub fn nonzeroing_move_hints(&self) -> bool {
 521         self.opts.debugging_opts.enable_nonzeroing_move_hints
 522     }
 523     pub fn overflow_checks(&self) -> bool {
 524         self.opts.cg.overflow_checks
 525             .or(self.opts.debugging_opts.force_overflow_checks)
 526             .unwrap_or(self.opts.debug_assertions)
 527     }
 528
 529     pub fn crt_static(&self) -> bool {
 530         // If the target does not opt in to crt-static support, use its default.
 531         if self.target.target.options.crt_static_respected {
 532             self.crt_static_feature()
 533         } else {
 534             self.target.target.options.crt_static_default
 535         }
 536     }
 537
 538     pub fn crt_static_feature(&self) -> bool {
 539         let requested_features = self.opts.cg.target_feature.split(',');
 540         let found_negative = requested_features.clone().any(|r| r == "-crt-static");
 541         let found_positive = requested_features.clone().any(|r| r == "+crt-static");
 542
 543         // If the target we're compiling for requests a static crt by default,
 544         // then see if the `-crt-static` feature was passed to disable that.
 545         // Otherwise if we don't have a static crt by default then see if the
 546         // `+crt-static` feature was passed.
 547         if self.target.target.options.crt_static_default {
 548             !found_negative
 549         } else {
 550             found_positive
 551         }
 552     }
 553
 554     pub fn must_not_eliminate_frame_pointers(&self) -> bool {
 555         self.opts.debuginfo != DebugInfoLevel::NoDebugInfo ||
 556         !self.target.target.options.eliminate_frame_pointer
 557     }
 558
 559     /// Returns the symbol name for the registrar function,
 560     /// given the crate Svh and the function DefIndex.
 561     pub fn generate_plugin_registrar_symbol(&self,
 562                                             disambiguator: CrateDisambiguator)
 563                                             -> String {
 564         format!("__rustc_plugin_registrar_{}__", disambiguator.to_fingerprint().to_hex())
 565     }
 566
 567     pub fn generate_derive_registrar_symbol(&self,
 568                                             disambiguator: CrateDisambiguator)
 569                                             -> String {
 570         format!("__rustc_derive_registrar_{}__", disambiguator.to_fingerprint().to_hex())
 571     }
 572
 573     pub fn sysroot<'a>(&'a self) -> &'a Path {
 574         match self.opts.maybe_sysroot {
 575             Some (ref sysroot) => sysroot,
 576             None => self.default_sysroot.as_ref()
 577                         .expect("missing sysroot and default_sysroot in Session")
 578         }
 579     }
 580     pub fn target_filesearch(&self, kind: PathKind) -> filesearch::FileSearch {
 581         filesearch::FileSearch::new(self.sysroot(),
 582                                     &self.opts.target_triple,
 583                                     &self.opts.search_paths,
 584                                     kind)
 585     }
 586     pub fn host_filesearch(&self, kind: PathKind) -> filesearch::FileSearch {
 587         filesearch::FileSearch::new(
 588             self.sysroot(),
 589             config::host_triple(),
 590             &self.opts.search_paths,
 591             kind)
 592     }
 593
 594     pub fn set_incr_session_load_dep_graph(&self, load: bool) {
 595         let mut incr_comp_session = self.incr_comp_session.borrow_mut();
 596
 597         match *incr_comp_session {
 598             IncrCompSession::Active { ref mut load_dep_graph, .. } => {
 599                 *load_dep_graph = load;
 600             }
 601             _ => {}
 602         }
 603     }
 604
 605     pub fn incr_session_load_dep_graph(&self) -> bool {
 606         let incr_comp_session = self.incr_comp_session.borrow();
 607         match *incr_comp_session {
 608             IncrCompSession::Active { load_dep_graph, .. } => load_dep_graph,
 609             _ => false,
 610         }
 611     }
 612
 613     pub fn init_incr_comp_session(&self,
 614                                   session_dir: PathBuf,
 615                                   lock_file: flock::Lock,
 616                                   load_dep_graph: bool) {
 617         let mut incr_comp_session = self.incr_comp_session.borrow_mut();
 618
 619         if let IncrCompSession::NotInitialized = *incr_comp_session { } else {
 620             bug!("Trying to initialize IncrCompSession `{:?}`", *incr_comp_session)
 621         }
 622
 623         *incr_comp_session = IncrCompSession::Active {
 624             session_directory: session_dir,
 625             lock_file,
 626             load_dep_graph,
 627         };
 628     }
 629
 630     pub fn finalize_incr_comp_session(&self, new_directory_path: PathBuf) {
 631         let mut incr_comp_session = self.incr_comp_session.borrow_mut();
 632
 633         if let IncrCompSession::Active { .. } = *incr_comp_session { } else {
 634             bug!("Trying to finalize IncrCompSession `{:?}`", *incr_comp_session)
 635         }
 636
 637         // Note: This will also drop the lock file, thus unlocking the directory
 638         *incr_comp_session = IncrCompSession::Finalized {
 639             session_directory: new_directory_path,
 640         };
 641     }
 642
 643     pub fn mark_incr_comp_session_as_invalid(&self) {
 644         let mut incr_comp_session = self.incr_comp_session.borrow_mut();
 645
 646         let session_directory = match *incr_comp_session {
 647             IncrCompSession::Active { ref session_directory, .. } => {
 648                 session_directory.clone()
 649             }
 650             _ => bug!("Trying to invalidate IncrCompSession `{:?}`",
 651                       *incr_comp_session),
 652         };
 653
 654         // Note: This will also drop the lock file, thus unlocking the directory
 655         *incr_comp_session = IncrCompSession::InvalidBecauseOfErrors {
 656             session_directory,
 657         };
 658     }
 659
 660     pub fn incr_comp_session_dir(&self) -> cell::Ref<PathBuf> {
 661         let incr_comp_session = self.incr_comp_session.borrow();
 662         cell::Ref::map(incr_comp_session, |incr_comp_session| {
 663             match *incr_comp_session {
 664                 IncrCompSession::NotInitialized => {
 665                     bug!("Trying to get session directory from IncrCompSession `{:?}`",
 666                         *incr_comp_session)
 667                 }
 668                 IncrCompSession::Active { ref session_directory, .. } |
 669                 IncrCompSession::Finalized { ref session_directory } |
 670                 IncrCompSession::InvalidBecauseOfErrors { ref session_directory } => {
 671                     session_directory
 672                 }
 673             }
 674         })
 675     }
 676
 677     pub fn incr_comp_session_dir_opt(&self) -> Option<cell::Ref<PathBuf>> {
 678         if self.opts.incremental.is_some() {
 679             Some(self.incr_comp_session_dir())
 680         } else {
 681             None
 682         }
 683     }
 684
 685     pub fn print_perf_stats(&self) {
 686         println!("Total time spent computing SVHs:               {}",
 687                  duration_to_secs_str(self.perf_stats.svh_time.get()));
 688         println!("Total time spent computing incr. comp. hashes: {}",
 689                  duration_to_secs_str(self.perf_stats.incr_comp_hashes_time.get()));
 690         println!("Total number of incr. comp. hashes computed:   {}",
 691                  self.perf_stats.incr_comp_hashes_count.get());
 692         println!("Total number of bytes hashed for incr. comp.:  {}",
 693                  self.perf_stats.incr_comp_bytes_hashed.get());
 694         if self.perf_stats.incr_comp_hashes_count.get() != 0 {
 695             println!("Average bytes hashed per incr. comp. HIR node: {}",
 696                     self.perf_stats.incr_comp_bytes_hashed.get() /
 697                     self.perf_stats.incr_comp_hashes_count.get());
 698         } else {
 699             println!("Average bytes hashed per incr. comp. HIR node: N/A");
 700         }
 701         println!("Total time spent computing symbol hashes:      {}",
 702                  duration_to_secs_str(self.perf_stats.symbol_hash_time.get()));
 703         println!("Total time spent decoding DefPath tables:      {}",
 704                  duration_to_secs_str(self.perf_stats.decode_def_path_tables_time.get()));
 705     }
 706
 707     /// We want to know if we're allowed to do an optimization for crate foo from -z fuel=foo=n.
 708     /// This expends fuel if applicable, and records fuel if applicable.
 709     pub fn consider_optimizing<T: Fn() -> String>(&self, crate_name: &str, msg: T) -> bool {
 710         let mut ret = true;
 711         match self.optimization_fuel_crate {
 712             Some(ref c) if c == crate_name => {
 713                 let fuel = self.optimization_fuel_limit.get();
 714                 ret = fuel != 0;
 715                 if fuel == 0 && !self.out_of_fuel.get() {
 716                     println!("optimization-fuel-exhausted: {}", msg());
 717                     self.out_of_fuel.set(true);
 718                 } else if fuel > 0 {
 719                     self.optimization_fuel_limit.set(fuel-1);
 720                 }
 721             }
 722             _ => {}
 723         }
 724         match self.print_fuel_crate {
 725             Some(ref c) if c == crate_name=> {
 726                 self.print_fuel.set(self.print_fuel.get()+1);
 727             },
 728             _ => {}
 729         }
 730         ret
 731     }
 732
 733     /// Returns the number of query threads that should be used for this
 734     /// compilation
 735     pub fn query_threads(&self) -> usize {
 736         self.opts.debugging_opts.query_threads.unwrap_or(1)
 737     }
 738
 739     /// Returns the number of codegen units that should be used for this
 740     /// compilation
 741     pub fn codegen_units(&self) -> usize {
 742         if let Some(n) = self.opts.cli_forced_codegen_units {
 743             return n
 744         }
 745         if let Some(n) = self.target.target.options.default_codegen_units {
 746             return n as usize
 747         }
 748
 749         // Why is 16 codegen units the default all the time?
 750         //
 751         // The main reason for enabling multiple codegen units by default is to
 752         // leverage the ability for the trans backend to do translation and
 753         // codegen in parallel. This allows us, especially for large crates, to
 754         // make good use of all available resources on the machine once we've
 755         // hit that stage of compilation. Large crates especially then often
 756         // take a long time in trans/codegen and this helps us amortize that
 757         // cost.
 758         //
 759         // Note that a high number here doesn't mean that we'll be spawning a
 760         // large number of threads in parallel. The backend of rustc contains
 761         // global rate limiting through the `jobserver` crate so we'll never
 762         // overload the system with too much work, but rather we'll only be
 763         // optimizing when we're otherwise cooperating with other instances of
 764         // rustc.
 765         //
 766         // Rather a high number here means that we should be able to keep a lot
 767         // of idle cpus busy. By ensuring that no codegen unit takes *too* long
 768         // to build we'll be guaranteed that all cpus will finish pretty closely
 769         // to one another and we should make relatively optimal use of system
 770         // resources
 771         //
 772         // Note that the main cost of codegen units is that it prevents LLVM
 773         // from inlining across codegen units. Users in general don't have a lot
 774         // of control over how codegen units are split up so it's our job in the
 775         // compiler to ensure that undue performance isn't lost when using
 776         // codegen units (aka we can't require everyone to slap `#[inline]` on
 777         // everything).
 778         //
 779         // If we're compiling at `-O0` then the number doesn't really matter too
 780         // much because performance doesn't matter and inlining is ok to lose.
 781         // In debug mode we just want to try to guarantee that no cpu is stuck
 782         // doing work that could otherwise be farmed to others.
 783         //
 784         // In release mode, however (O1 and above) performance does indeed
 785         // matter! To recover the loss in performance due to inlining we'll be
 786         // enabling ThinLTO by default (the function for which is just below).
 787         // This will ensure that we recover any inlining wins we otherwise lost
 788         // through codegen unit partitioning.
 789         //
 790         // ---
 791         //
 792         // Ok that's a lot of words but the basic tl;dr; is that we want a high
 793         // number here -- but not too high. Additionally we're "safe" to have it
 794         // always at the same number at all optimization levels.
 795         //
 796         // As a result 16 was chosen here! Mostly because it was a power of 2
 797         // and most benchmarks agreed it was roughly a local optimum. Not very
 798         // scientific.
 799         16
 800     }
 801
 802     /// Returns whether ThinLTO is enabled for this compilation
 803     pub fn thinlto(&self) -> bool {
 804         // If processing command line options determined that we're incompatible
 805         // with ThinLTO (e.g. `-C lto --emit llvm-ir`) then return that option.
 806         if let Some(enabled) = self.opts.cli_forced_thinlto {
 807             return enabled
 808         }
 809
 810         // If explicitly specified, use that with the next highest priority
 811         if let Some(enabled) = self.opts.debugging_opts.thinlto {
 812             return enabled
 813         }
 814
 815         // If LTO is enabled we right now unconditionally disable ThinLTO.
 816         // This'll come at a later date! (full crate graph ThinLTO)
 817         if self.lto() {
 818             return false
 819         }
 820
 821         // If there's only one codegen unit or then there's no need for ThinLTO
 822         // so just return false.
 823         if self.codegen_units() == 1 {
 824             return false
 825         }
 826
 827         // Right now ThinLTO isn't compatible with incremental compilation.
 828         if self.opts.incremental.is_some() {
 829             return false
 830         }
 831
 832         // Now we're in "defaults" territory. By default we enable ThinLTO for
 833         // optimized compiles (anything greater than O0).
 834         match self.opts.optimize {
 835             config::OptLevel::No => false,
 836             _ => true,
 837         }
 838     }
 839 }
 840
 841 pub fn build_session(sopts: config::Options,
 842                      local_crate_source_file: Option<PathBuf>,
 843                      registry: errors::registry::Registry)
 844                      -> Session {
 845     let file_path_mapping = sopts.file_path_mapping();
 846
 847     build_session_with_codemap(sopts,
 848                                local_crate_source_file,
 849                                registry,
 850                                Rc::new(codemap::CodeMap::new(file_path_mapping)),
 851                                None)
 852 }
 853
 854 pub fn build_session_with_codemap(sopts: config::Options,
 855                                   local_crate_source_file: Option<PathBuf>,
 856                                   registry: errors::registry::Registry,
 857                                   codemap: Rc<codemap::CodeMap>,
 858                                   emitter_dest: Option<Box<Write + Send>>)
 859                                   -> Session {
 860     // FIXME: This is not general enough to make the warning lint completely override
 861     // normal diagnostic warnings, since the warning lint can also be denied and changed
 862     // later via the source code.
 863     let warnings_allow = sopts.lint_opts
 864         .iter()
 865         .filter(|&&(ref key, _)| *key == "warnings")
 866         .map(|&(_, ref level)| *level == lint::Allow)
 867         .last()
 868         .unwrap_or(false);
 869     let cap_lints_allow = sopts.lint_cap.map_or(false, |cap| cap == lint::Allow);
 870
 871     let can_emit_warnings = !(warnings_allow || cap_lints_allow);
 872
 873     let treat_err_as_bug = sopts.debugging_opts.treat_err_as_bug;
 874
 875     let external_macro_backtrace = sopts.debugging_opts.external_macro_backtrace;
 876
 877     let emitter: Box<Emitter> = match (sopts.error_format, emitter_dest) {
 878         (config::ErrorOutputType::HumanReadable(color_config), None) => {
 879             Box::new(EmitterWriter::stderr(color_config, Some(codemap.clone()), false))
 880         }
 881         (config::ErrorOutputType::HumanReadable(_), Some(dst)) => {
 882             Box::new(EmitterWriter::new(dst, Some(codemap.clone()), false))
 883         }
 884         (config::ErrorOutputType::Json(pretty), None) => {
 885             Box::new(JsonEmitter::stderr(Some(registry), codemap.clone(), pretty))
 886         }
 887         (config::ErrorOutputType::Json(pretty), Some(dst)) => {
 888             Box::new(JsonEmitter::new(dst, Some(registry), codemap.clone(), pretty))
 889         }
 890         (config::ErrorOutputType::Short(color_config), None) => {
 891             Box::new(EmitterWriter::stderr(color_config, Some(codemap.clone()), true))
 892         }
 893         (config::ErrorOutputType::Short(_), Some(dst)) => {
 894             Box::new(EmitterWriter::new(dst, Some(codemap.clone()), true))
 895         }
 896     };
 897
 898     let diagnostic_handler =
 899         errors::Handler::with_emitter_and_flags(
 900             emitter,
 901             errors::HandlerFlags {
 902                 can_emit_warnings,
 903                 treat_err_as_bug,
 904                 external_macro_backtrace,
 905                 .. Default::default()
 906             });
 907
 908     build_session_(sopts,
 909                    local_crate_source_file,
 910                    diagnostic_handler,
 911                    codemap)
 912 }
 913
 914 pub fn build_session_(sopts: config::Options,
 915                       local_crate_source_file: Option<PathBuf>,
 916                       span_diagnostic: errors::Handler,
 917                       codemap: Rc<codemap::CodeMap>)
 918                       -> Session {
 919     let host = match Target::search(config::host_triple()) {
 920         Ok(t) => t,
 921         Err(e) => {
 922             panic!(span_diagnostic.fatal(&format!("Error loading host specification: {}", e)));
 923         }
 924     };
 925     let target_cfg = config::build_target_config(&sopts, &span_diagnostic);
 926
 927     let p_s = parse::ParseSess::with_span_handler(span_diagnostic, codemap);
 928     let default_sysroot = match sopts.maybe_sysroot {
 929         Some(_) => None,
 930         None => Some(filesearch::get_or_default_sysroot())
 931     };
 932
 933     let file_path_mapping = sopts.file_path_mapping();
 934
 935     let local_crate_source_file = local_crate_source_file.map(|path| {
 936         file_path_mapping.map_prefix(path).0
 937     });
 938
 939     let optimization_fuel_crate = sopts.debugging_opts.fuel.as_ref().map(|i| i.0.clone());
 940     let optimization_fuel_limit = Cell::new(sopts.debugging_opts.fuel.as_ref()
 941         .map(|i| i.1).unwrap_or(0));
 942     let print_fuel_crate = sopts.debugging_opts.print_fuel.clone();
 943     let print_fuel = Cell::new(0);
 944
 945     let working_dir = match env::current_dir() {
 946         Ok(dir) => dir,
 947         Err(e) => {
 948             panic!(p_s.span_diagnostic.fatal(&format!("Current directory is invalid: {}", e)))
 949         }
 950     };
 951     let working_dir = file_path_mapping.map_prefix(working_dir);
 952
 953     let sess = Session {
 954         target: target_cfg,
 955         host,
 956         opts: sopts,
 957         parse_sess: p_s,
 958         // For a library crate, this is always none
 959         entry_fn: RefCell::new(None),
 960         entry_type: Cell::new(None),
 961         plugin_registrar_fn: Cell::new(None),
 962         derive_registrar_fn: Cell::new(None),
 963         default_sysroot,
 964         local_crate_source_file,
 965         working_dir,
 966         lint_store: RefCell::new(lint::LintStore::new()),
 967         buffered_lints: RefCell::new(Some(lint::LintBuffer::new())),
 968         one_time_diagnostics: RefCell::new(FxHashSet()),
 969         plugin_llvm_passes: RefCell::new(Vec::new()),
 970         plugin_attributes: RefCell::new(Vec::new()),
 971         crate_types: RefCell::new(Vec::new()),
 972         dependency_formats: RefCell::new(FxHashMap()),
 973         crate_disambiguator: RefCell::new(None),
 974         features: RefCell::new(feature_gate::Features::new()),
 975         recursion_limit: Cell::new(64),
 976         type_length_limit: Cell::new(1048576),
 977         next_node_id: Cell::new(NodeId::new(1)),
 978         injected_allocator: Cell::new(None),
 979         allocator_kind: Cell::new(None),
 980         injected_panic_runtime: Cell::new(None),
 981         imported_macro_spans: RefCell::new(HashMap::new()),
 982         incr_comp_session: RefCell::new(IncrCompSession::NotInitialized),
 983         perf_stats: PerfStats {
 984             svh_time: Cell::new(Duration::from_secs(0)),
 985             incr_comp_hashes_time: Cell::new(Duration::from_secs(0)),
 986             incr_comp_hashes_count: Cell::new(0),
 987             incr_comp_bytes_hashed: Cell::new(0),
 988             symbol_hash_time: Cell::new(Duration::from_secs(0)),
 989             decode_def_path_tables_time: Cell::new(Duration::from_secs(0)),
 990         },
 991         code_stats: RefCell::new(CodeStats::new()),
 992         optimization_fuel_crate,
 993         optimization_fuel_limit,
 994         print_fuel_crate,
 995         print_fuel,
 996         out_of_fuel: Cell::new(false),
 997         // Note that this is unsafe because it may misinterpret file descriptors
 998         // on Unix as jobserver file descriptors. We hopefully execute this near
 999         // the beginning of the process though to ensure we don't get false
1000         // positives, or in other words we try to execute this before we open
1001         // any file descriptors ourselves.
1002         //
1003         // Also note that we stick this in a global because there could be
1004         // multiple `Session` instances in this process, and the jobserver is
1005         // per-process.
1006         jobserver_from_env: unsafe {
1007             static mut GLOBAL_JOBSERVER: *mut Option<Client> = 0 as *mut _;
1008             static INIT: Once = ONCE_INIT;
1009             INIT.call_once(|| {
1010                 GLOBAL_JOBSERVER = Box::into_raw(Box::new(Client::from_env()));
1011             });
1012             (*GLOBAL_JOBSERVER).clone()
1013         },
1014         has_global_allocator: Cell::new(false),
1015     };
1016
1017     sess
1018 }
1019
1020 /// Hash value constructed out of all the `-C metadata` arguments passed to the
1021 /// compiler. Together with the crate-name forms a unique global identifier for
1022 /// the crate.
1023 #[derive(Eq, PartialEq, Ord, PartialOrd, Hash, Debug, Clone, Copy, RustcEncodable, RustcDecodable)]
1024 pub struct CrateDisambiguator(Fingerprint);
1025
1026 impl CrateDisambiguator {
1027     pub fn to_fingerprint(self) -> Fingerprint {
1028         self.0
1029     }
1030 }
1031
1032 impl From<Fingerprint> for CrateDisambiguator {
1033     fn from(fingerprint: Fingerprint) -> CrateDisambiguator {
1034         CrateDisambiguator(fingerprint)
1035     }
1036 }
1037
1038 impl_stable_hash_for!(tuple_struct CrateDisambiguator { fingerprint });
1039
1040 /// Holds data on the current incremental compilation session, if there is one.
1041 #[derive(Debug)]
1042 pub enum IncrCompSession {
1043     /// This is the state the session will be in until the incr. comp. dir is
1044     /// needed.
1045     NotInitialized,
1046     /// This is the state during which the session directory is private and can
1047     /// be modified.
1048     Active {
1049         session_directory: PathBuf,
1050         lock_file: flock::Lock,
1051         load_dep_graph: bool,
1052     },
1053     /// This is the state after the session directory has been finalized. In this
1054     /// state, the contents of the directory must not be modified any more.
1055     Finalized {
1056         session_directory: PathBuf,
1057     },
1058     /// This is an error state that is reached when some compilation error has
1059     /// occurred. It indicates that the contents of the session directory must
1060     /// not be used, since they might be invalid.
1061     InvalidBecauseOfErrors {
1062         session_directory: PathBuf,
1063     }
1064 }
1065
1066 pub fn early_error(output: config::ErrorOutputType, msg: &str) -> ! {
1067     let emitter: Box<Emitter> = match output {
1068         config::ErrorOutputType::HumanReadable(color_config) => {
1069             Box::new(EmitterWriter::stderr(color_config, None, false))
1070         }
1071         config::ErrorOutputType::Json(pretty) => Box::new(JsonEmitter::basic(pretty)),
1072         config::ErrorOutputType::Short(color_config) => {
1073             Box::new(EmitterWriter::stderr(color_config, None, true))
1074         }
1075     };
1076     let handler = errors::Handler::with_emitter(true, false, emitter);
1077     handler.emit(&MultiSpan::new(), msg, errors::Level::Fatal);
1078     panic!(errors::FatalError);
1079 }
1080
1081 pub fn early_warn(output: config::ErrorOutputType, msg: &str) {
1082     let emitter: Box<Emitter> = match output {
1083         config::ErrorOutputType::HumanReadable(color_config) => {
1084             Box::new(EmitterWriter::stderr(color_config, None, false))
1085         }
1086         config::ErrorOutputType::Json(pretty) => Box::new(JsonEmitter::basic(pretty)),
1087         config::ErrorOutputType::Short(color_config) => {
1088             Box::new(EmitterWriter::stderr(color_config, None, true))
1089         }
1090     };
1091     let handler = errors::Handler::with_emitter(true, false, emitter);
1092     handler.emit(&MultiSpan::new(), msg, errors::Level::Warning);
1093 }
1094
1095 #[derive(Copy, Clone, Debug)]
1096 pub enum CompileIncomplete {
1097     Stopped,
1098     Errored(ErrorReported)
1099 }
1100 impl From<ErrorReported> for CompileIncomplete {
1101     fn from(err: ErrorReported) -> CompileIncomplete {
1102         CompileIncomplete::Errored(err)
1103     }
1104 }
1105 pub type CompileResult = Result<(), CompileIncomplete>;
1106
1107 pub fn compile_result_from_err_count(err_count: usize) -> CompileResult {
1108     if err_count == 0 {
1109         Ok(())
1110     } else {
1111         Err(CompileIncomplete::Errored(ErrorReported))
1112     }
1113 }
1114
1115 #[cold]
1116 #[inline(never)]
1117 pub fn bug_fmt(file: &'static str, line: u32, args: fmt::Arguments) -> ! {
1118     // this wrapper mostly exists so I don't have to write a fully
1119     // qualified path of None::<Span> inside the bug!() macro definition
1120     opt_span_bug_fmt(file, line, None::<Span>, args);
1121 }
1122
1123 #[cold]
1124 #[inline(never)]
1125 pub fn span_bug_fmt<S: Into<MultiSpan>>(file: &'static str,
1126                                         line: u32,
1127                                         span: S,
1128                                         args: fmt::Arguments) -> ! {
1129     opt_span_bug_fmt(file, line, Some(span), args);
1130 }
1131
1132 fn opt_span_bug_fmt<S: Into<MultiSpan>>(file: &'static str,
1133                                         line: u32,
1134                                         span: Option<S>,
1135                                         args: fmt::Arguments) -> ! {
1136     tls::with_opt(move |tcx| {
1137         let msg = format!("{}:{}: {}", file, line, args);
1138         match (tcx, span) {
1139             (Some(tcx), Some(span)) => tcx.sess.diagnostic().span_bug(span, &msg),
1140             (Some(tcx), None) => tcx.sess.diagnostic().bug(&msg),
1141             (None, _) => panic!(msg)
1142         }
1143     });
1144     unreachable!();
1145 }