src/librustc_driver/driver.rs

   1 // Copyright 2012-2015 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 use rustc::dep_graph::DepGraph;
  12 use rustc::hir::{self, map as hir_map};
  13 use rustc::hir::lowering::lower_crate;
  14 use rustc::ich::Fingerprint;
  15 use rustc_data_structures::stable_hasher::StableHasher;
  16 use rustc_mir as mir;
  17 use rustc::session::{Session, CompileResult, CrateDisambiguator};
  18 use rustc::session::CompileIncomplete;
  19 use rustc::session::config::{self, Input, OutputFilenames, OutputType};
  20 use rustc::session::search_paths::PathKind;
  21 use rustc::lint;
  22 use rustc::middle::{self, stability, reachable};
  23 use rustc::middle::cstore::CrateStore;
  24 use rustc::middle::privacy::AccessLevels;
  25 use rustc::ty::{self, TyCtxt, Resolutions, GlobalArenas};
  26 use rustc::traits;
  27 use rustc::util::common::{ErrorReported, time};
  28 use rustc_allocator as allocator;
  29 use rustc_borrowck as borrowck;
  30 use rustc_incremental;
  31 use rustc_resolve::{MakeGlobMap, Resolver};
  32 use rustc_metadata::creader::CrateLoader;
  33 use rustc_metadata::cstore::{self, CStore};
  34 use rustc_trans as trans;
  35 use rustc_trans_utils::trans_crate::TransCrate;
  36 use rustc_typeck as typeck;
  37 use rustc_privacy;
  38 use rustc_plugin::registry::Registry;
  39 use rustc_plugin as plugin;
  40 use rustc_passes::{self, ast_validation, no_asm, loops, consts, static_recursion, hir_stats};
  41 use rustc_const_eval::{self, check_match};
  42 use super::Compilation;
  43 use ::DefaultTransCrate;
  44
  45 use serialize::json;
  46
  47 use std::any::Any;
  48 use std::env;
  49 use std::ffi::{OsString, OsStr};
  50 use std::fs;
  51 use std::io::{self, Write};
  52 use std::iter;
  53 use std::path::{Path, PathBuf};
  54 use std::rc::Rc;
  55 use std::sync::mpsc;
  56 use syntax::{ast, diagnostics, visit};
  57 use syntax::attr;
  58 use syntax::ext::base::ExtCtxt;
  59 use syntax::parse::{self, PResult};
  60 use syntax::util::node_count::NodeCounter;
  61 use syntax;
  62 use syntax_ext;
  63 use arena::DroplessArena;
  64
  65 use derive_registrar;
  66
  67 use profile;
  68
  69 pub fn compile_input(sess: &Session,
  70                      cstore: &CStore,
  71                      input: &Input,
  72                      outdir: &Option<PathBuf>,
  73                      output: &Option<PathBuf>,
  74                      addl_plugins: Option<Vec<String>>,
  75                      control: &CompileController) -> CompileResult {
  76     use rustc::session::config::CrateType;
  77
  78     macro_rules! controller_entry_point {
  79         ($point: ident, $tsess: expr, $make_state: expr, $phase_result: expr) => {{
  80             let state = &mut $make_state;
  81             let phase_result: &CompileResult = &$phase_result;
  82             if phase_result.is_ok() || control.$point.run_callback_on_error {
  83                 (control.$point.callback)(state);
  84             }
  85
  86             if control.$point.stop == Compilation::Stop {
  87                 // FIXME: shouldn't this return Err(CompileIncomplete::Stopped)
  88                 // if there are no errors?
  89                 return $tsess.compile_status();
  90             }
  91         }}
  92     }
  93
  94     if cfg!(not(feature="llvm")) {
  95         for cty in sess.opts.crate_types.iter() {
  96             match *cty {
  97                 CrateType::CrateTypeRlib | CrateType::CrateTypeDylib |
  98                 CrateType::CrateTypeExecutable => {},
  99                 _ => {
 100                     sess.parse_sess.span_diagnostic.warn(
 101                         &format!("LLVM unsupported, so output type {} is not supported", cty)
 102                     );
 103                 },
 104             }
 105         }
 106
 107         sess.abort_if_errors();
 108     }
 109
 110     if sess.profile_queries() {
 111         profile::begin();
 112     }
 113
 114     // We need nested scopes here, because the intermediate results can keep
 115     // large chunks of memory alive and we want to free them as soon as
 116     // possible to keep the peak memory usage low
 117     let (outputs, trans, dep_graph) = {
 118         let krate = match phase_1_parse_input(control, sess, input) {
 119             Ok(krate) => krate,
 120             Err(mut parse_error) => {
 121                 parse_error.emit();
 122                 return Err(CompileIncomplete::Errored(ErrorReported));
 123             }
 124         };
 125
 126         let (krate, registry) = {
 127             let mut compile_state = CompileState::state_after_parse(input,
 128                                                                     sess,
 129                                                                     outdir,
 130                                                                     output,
 131                                                                     krate,
 132                                                                     &cstore);
 133             controller_entry_point!(after_parse,
 134                                     sess,
 135                                     compile_state,
 136                                     Ok(()));
 137
 138             (compile_state.krate.unwrap(), compile_state.registry)
 139         };
 140
 141         let outputs = build_output_filenames(input, outdir, output, &krate.attrs, sess);
 142         let crate_name =
 143             ::rustc_trans_utils::link::find_crate_name(Some(sess), &krate.attrs, input);
 144         let ExpansionResult { expanded_crate, defs, analysis, resolutions, mut hir_forest } = {
 145             phase_2_configure_and_expand(
 146                 sess,
 147                 &cstore,
 148                 krate,
 149                 registry,
 150                 &crate_name,
 151                 addl_plugins,
 152                 control.make_glob_map,
 153                 |expanded_crate| {
 154                     let mut state = CompileState::state_after_expand(
 155                         input, sess, outdir, output, &cstore, expanded_crate, &crate_name,
 156                     );
 157                     controller_entry_point!(after_expand, sess, state, Ok(()));
 158                     Ok(())
 159                 }
 160             )?
 161         };
 162
 163         write_out_deps(sess, &outputs, &crate_name);
 164         if sess.opts.output_types.contains_key(&OutputType::DepInfo) &&
 165             sess.opts.output_types.keys().count() == 1 {
 166             return Ok(())
 167         }
 168
 169         let arena = DroplessArena::new();
 170         let arenas = GlobalArenas::new();
 171
 172         // Construct the HIR map
 173         let hir_map = time(sess.time_passes(),
 174                            "indexing hir",
 175                            || hir_map::map_crate(sess, cstore, &mut hir_forest, &defs));
 176
 177         {
 178             let _ignore = hir_map.dep_graph.in_ignore();
 179             controller_entry_point!(after_hir_lowering,
 180                                     sess,
 181                                     CompileState::state_after_hir_lowering(input,
 182                                                                   sess,
 183                                                                   outdir,
 184                                                                   output,
 185                                                                   &arena,
 186                                                                   &arenas,
 187                                                                   &cstore,
 188                                                                   &hir_map,
 189                                                                   &analysis,
 190                                                                   &resolutions,
 191                                                                   &expanded_crate,
 192                                                                   &hir_map.krate(),
 193                                                                   &outputs,
 194                                                                   &crate_name),
 195                                     Ok(()));
 196         }
 197
 198         time(sess.time_passes(), "attribute checking", || {
 199             hir::check_attr::check_crate(sess, &expanded_crate);
 200         });
 201
 202         let opt_crate = if control.keep_ast {
 203             Some(&expanded_crate)
 204         } else {
 205             drop(expanded_crate);
 206             None
 207         };
 208
 209         phase_3_run_analysis_passes(control,
 210                                     sess,
 211                                     cstore,
 212                                     hir_map,
 213                                     analysis,
 214                                     resolutions,
 215                                     &arena,
 216                                     &arenas,
 217                                     &crate_name,
 218                                     &outputs,
 219                                     |tcx, analysis, rx, result| {
 220             {
 221                 // Eventually, we will want to track plugins.
 222                 let _ignore = tcx.dep_graph.in_ignore();
 223
 224                 let mut state = CompileState::state_after_analysis(input,
 225                                                                    sess,
 226                                                                    outdir,
 227                                                                    output,
 228                                                                    opt_crate,
 229                                                                    tcx.hir.krate(),
 230                                                                    &analysis,
 231                                                                    tcx,
 232                                                                    &crate_name);
 233                 (control.after_analysis.callback)(&mut state);
 234
 235                 if control.after_analysis.stop == Compilation::Stop {
 236                     return result.and_then(|_| Err(CompileIncomplete::Stopped));
 237                 }
 238             }
 239
 240             result?;
 241
 242             if log_enabled!(::log::LogLevel::Info) {
 243                 println!("Pre-trans");
 244                 tcx.print_debug_stats();
 245             }
 246
 247             let trans = phase_4_translate_to_llvm::<DefaultTransCrate>(tcx, rx);
 248
 249             if log_enabled!(::log::LogLevel::Info) {
 250                 println!("Post-trans");
 251                 tcx.print_debug_stats();
 252             }
 253
 254             if tcx.sess.opts.output_types.contains_key(&OutputType::Mir) {
 255                 if let Err(e) = mir::transform::dump_mir::emit_mir(tcx, &outputs) {
 256                     sess.err(&format!("could not emit MIR: {}", e));
 257                     sess.abort_if_errors();
 258                 }
 259             }
 260
 261             Ok((outputs.clone(), trans, tcx.dep_graph.clone()))
 262         })??
 263     };
 264
 265     if sess.opts.debugging_opts.print_type_sizes {
 266         sess.code_stats.borrow().print_type_sizes();
 267     }
 268
 269     let (phase5_result, trans) =
 270         phase_5_run_llvm_passes::<DefaultTransCrate>(sess, &dep_graph, trans);
 271
 272     controller_entry_point!(after_llvm,
 273                             sess,
 274                             CompileState::state_after_llvm(input, sess, outdir, output, &trans),
 275                             phase5_result);
 276     phase5_result?;
 277
 278     // Run the linker on any artifacts that resulted from the LLVM run.
 279     // This should produce either a finished executable or library.
 280     time(sess.time_passes(), "linking", || {
 281         DefaultTransCrate::link_binary(sess, &trans, &outputs)
 282     });
 283
 284     // Now that we won't touch anything in the incremental compilation directory
 285     // any more, we can finalize it (which involves renaming it)
 286     #[cfg(feature="llvm")]
 287     rustc_incremental::finalize_session_directory(sess, trans.link.crate_hash);
 288
 289     if sess.opts.debugging_opts.perf_stats {
 290         sess.print_perf_stats();
 291     }
 292
 293     controller_entry_point!(
 294         compilation_done,
 295         sess,
 296         CompileState::state_when_compilation_done(input, sess, outdir, output),
 297         Ok(())
 298     );
 299
 300     Ok(())
 301 }
 302
 303 fn keep_hygiene_data(sess: &Session) -> bool {
 304     sess.opts.debugging_opts.keep_hygiene_data
 305 }
 306
 307
 308 /// The name used for source code that doesn't originate in a file
 309 /// (e.g. source from stdin or a string)
 310 pub fn anon_src() -> String {
 311     "<anon>".to_string()
 312 }
 313
 314 pub fn source_name(input: &Input) -> String {
 315     match *input {
 316         // FIXME (#9639): This needs to handle non-utf8 paths
 317         Input::File(ref ifile) => ifile.to_str().unwrap().to_string(),
 318         Input::Str { ref name, .. } => name.clone(),
 319     }
 320 }
 321
 322 /// CompileController is used to customize compilation, it allows compilation to
 323 /// be stopped and/or to call arbitrary code at various points in compilation.
 324 /// It also allows for various flags to be set to influence what information gets
 325 /// collected during compilation.
 326 ///
 327 /// This is a somewhat higher level controller than a Session - the Session
 328 /// controls what happens in each phase, whereas the CompileController controls
 329 /// whether a phase is run at all and whether other code (from outside the
 330 /// compiler) is run between phases.
 331 ///
 332 /// Note that if compilation is set to stop and a callback is provided for a
 333 /// given entry point, the callback is called before compilation is stopped.
 334 ///
 335 /// Expect more entry points to be added in the future.
 336 pub struct CompileController<'a> {
 337     pub after_parse: PhaseController<'a>,
 338     pub after_expand: PhaseController<'a>,
 339     pub after_hir_lowering: PhaseController<'a>,
 340     pub after_analysis: PhaseController<'a>,
 341     pub after_llvm: PhaseController<'a>,
 342     pub compilation_done: PhaseController<'a>,
 343
 344     // FIXME we probably want to group the below options together and offer a
 345     // better API, rather than this ad-hoc approach.
 346     pub make_glob_map: MakeGlobMap,
 347     // Whether the compiler should keep the ast beyond parsing.
 348     pub keep_ast: bool,
 349     // -Zcontinue-parse-after-error
 350     pub continue_parse_after_error: bool,
 351
 352     /// Allows overriding default rustc query providers,
 353     /// after `default_provide` has installed them.
 354     pub provide: Box<Fn(&mut ty::maps::Providers) + 'a>,
 355     /// Same as `provide`, but only for non-local crates,
 356     /// applied after `default_provide_extern`.
 357     pub provide_extern: Box<Fn(&mut ty::maps::Providers) + 'a>,
 358 }
 359
 360 impl<'a> CompileController<'a> {
 361     pub fn basic() -> CompileController<'a> {
 362         CompileController {
 363             after_parse: PhaseController::basic(),
 364             after_expand: PhaseController::basic(),
 365             after_hir_lowering: PhaseController::basic(),
 366             after_analysis: PhaseController::basic(),
 367             after_llvm: PhaseController::basic(),
 368             compilation_done: PhaseController::basic(),
 369             make_glob_map: MakeGlobMap::No,
 370             keep_ast: false,
 371             continue_parse_after_error: false,
 372             provide: box |_| {},
 373             provide_extern: box |_| {},
 374         }
 375     }
 376 }
 377
 378 pub struct PhaseController<'a> {
 379     pub stop: Compilation,
 380     // If true then the compiler will try to run the callback even if the phase
 381     // ends with an error. Note that this is not always possible.
 382     pub run_callback_on_error: bool,
 383     pub callback: Box<Fn(&mut CompileState) + 'a>,
 384 }
 385
 386 impl<'a> PhaseController<'a> {
 387     pub fn basic() -> PhaseController<'a> {
 388         PhaseController {
 389             stop: Compilation::Continue,
 390             run_callback_on_error: false,
 391             callback: box |_| {},
 392         }
 393     }
 394 }
 395
 396 /// State that is passed to a callback. What state is available depends on when
 397 /// during compilation the callback is made. See the various constructor methods
 398 /// (`state_*`) in the impl to see which data is provided for any given entry point.
 399 pub struct CompileState<'a, 'tcx: 'a> {
 400     pub input: &'a Input,
 401     pub session: &'tcx Session,
 402     pub krate: Option<ast::Crate>,
 403     pub registry: Option<Registry<'a>>,
 404     pub cstore: Option<&'tcx CStore>,
 405     pub crate_name: Option<&'a str>,
 406     pub output_filenames: Option<&'a OutputFilenames>,
 407     pub out_dir: Option<&'a Path>,
 408     pub out_file: Option<&'a Path>,
 409     pub arena: Option<&'tcx DroplessArena>,
 410     pub arenas: Option<&'tcx GlobalArenas<'tcx>>,
 411     pub expanded_crate: Option<&'a ast::Crate>,
 412     pub hir_crate: Option<&'a hir::Crate>,
 413     pub hir_map: Option<&'a hir_map::Map<'tcx>>,
 414     pub resolutions: Option<&'a Resolutions>,
 415     pub analysis: Option<&'a ty::CrateAnalysis>,
 416     pub tcx: Option<TyCtxt<'a, 'tcx, 'tcx>>,
 417     pub trans: Option<&'a trans::CrateTranslation>,
 418 }
 419
 420 impl<'a, 'tcx> CompileState<'a, 'tcx> {
 421     fn empty(input: &'a Input,
 422              session: &'tcx Session,
 423              out_dir: &'a Option<PathBuf>)
 424              -> Self {
 425         CompileState {
 426             input,
 427             session,
 428             out_dir: out_dir.as_ref().map(|s| &**s),
 429             out_file: None,
 430             arena: None,
 431             arenas: None,
 432             krate: None,
 433             registry: None,
 434             cstore: None,
 435             crate_name: None,
 436             output_filenames: None,
 437             expanded_crate: None,
 438             hir_crate: None,
 439             hir_map: None,
 440             resolutions: None,
 441             analysis: None,
 442             tcx: None,
 443             trans: None,
 444         }
 445     }
 446
 447     fn state_after_parse(input: &'a Input,
 448                          session: &'tcx Session,
 449                          out_dir: &'a Option<PathBuf>,
 450                          out_file: &'a Option<PathBuf>,
 451                          krate: ast::Crate,
 452                          cstore: &'tcx CStore)
 453                          -> Self {
 454         CompileState {
 455             // Initialize the registry before moving `krate`
 456             registry: Some(Registry::new(&session, krate.span)),
 457             krate: Some(krate),
 458             cstore: Some(cstore),
 459             out_file: out_file.as_ref().map(|s| &**s),
 460             ..CompileState::empty(input, session, out_dir)
 461         }
 462     }
 463
 464     fn state_after_expand(input: &'a Input,
 465                           session: &'tcx Session,
 466                           out_dir: &'a Option<PathBuf>,
 467                           out_file: &'a Option<PathBuf>,
 468                           cstore: &'tcx CStore,
 469                           expanded_crate: &'a ast::Crate,
 470                           crate_name: &'a str)
 471                           -> Self {
 472         CompileState {
 473             crate_name: Some(crate_name),
 474             cstore: Some(cstore),
 475             expanded_crate: Some(expanded_crate),
 476             out_file: out_file.as_ref().map(|s| &**s),
 477             ..CompileState::empty(input, session, out_dir)
 478         }
 479     }
 480
 481     fn state_after_hir_lowering(input: &'a Input,
 482                                 session: &'tcx Session,
 483                                 out_dir: &'a Option<PathBuf>,
 484                                 out_file: &'a Option<PathBuf>,
 485                                 arena: &'tcx DroplessArena,
 486                                 arenas: &'tcx GlobalArenas<'tcx>,
 487                                 cstore: &'tcx CStore,
 488                                 hir_map: &'a hir_map::Map<'tcx>,
 489                                 analysis: &'a ty::CrateAnalysis,
 490                                 resolutions: &'a Resolutions,
 491                                 krate: &'a ast::Crate,
 492                                 hir_crate: &'a hir::Crate,
 493                                 output_filenames: &'a OutputFilenames,
 494                                 crate_name: &'a str)
 495                                 -> Self {
 496         CompileState {
 497             crate_name: Some(crate_name),
 498             arena: Some(arena),
 499             arenas: Some(arenas),
 500             cstore: Some(cstore),
 501             hir_map: Some(hir_map),
 502             analysis: Some(analysis),
 503             resolutions: Some(resolutions),
 504             expanded_crate: Some(krate),
 505             hir_crate: Some(hir_crate),
 506             output_filenames: Some(output_filenames),
 507             out_file: out_file.as_ref().map(|s| &**s),
 508             ..CompileState::empty(input, session, out_dir)
 509         }
 510     }
 511
 512     fn state_after_analysis(input: &'a Input,
 513                             session: &'tcx Session,
 514                             out_dir: &'a Option<PathBuf>,
 515                             out_file: &'a Option<PathBuf>,
 516                             krate: Option<&'a ast::Crate>,
 517                             hir_crate: &'a hir::Crate,
 518                             analysis: &'a ty::CrateAnalysis,
 519                             tcx: TyCtxt<'a, 'tcx, 'tcx>,
 520                             crate_name: &'a str)
 521                             -> Self {
 522         CompileState {
 523             analysis: Some(analysis),
 524             tcx: Some(tcx),
 525             expanded_crate: krate,
 526             hir_crate: Some(hir_crate),
 527             crate_name: Some(crate_name),
 528             out_file: out_file.as_ref().map(|s| &**s),
 529             ..CompileState::empty(input, session, out_dir)
 530         }
 531     }
 532
 533     fn state_after_llvm(input: &'a Input,
 534                         session: &'tcx Session,
 535                         out_dir: &'a Option<PathBuf>,
 536                         out_file: &'a Option<PathBuf>,
 537                         trans: &'a trans::CrateTranslation)
 538                         -> Self {
 539         CompileState {
 540             trans: Some(trans),
 541             out_file: out_file.as_ref().map(|s| &**s),
 542             ..CompileState::empty(input, session, out_dir)
 543         }
 544     }
 545
 546     fn state_when_compilation_done(input: &'a Input,
 547                                    session: &'tcx Session,
 548                                    out_dir: &'a Option<PathBuf>,
 549                                    out_file: &'a Option<PathBuf>)
 550                                    -> Self {
 551         CompileState {
 552             out_file: out_file.as_ref().map(|s| &**s),
 553             ..CompileState::empty(input, session, out_dir)
 554         }
 555     }
 556 }
 557
 558 pub fn phase_1_parse_input<'a>(control: &CompileController,
 559                                sess: &'a Session,
 560                                input: &Input)
 561                                -> PResult<'a, ast::Crate> {
 562     sess.diagnostic().set_continue_after_error(control.continue_parse_after_error);
 563
 564     if sess.profile_queries() {
 565         profile::begin();
 566     }
 567
 568     let krate = time(sess.time_passes(), "parsing", || {
 569         match *input {
 570             Input::File(ref file) => {
 571                 parse::parse_crate_from_file(file, &sess.parse_sess)
 572             }
 573             Input::Str { ref input, ref name } => {
 574                 parse::parse_crate_from_source_str(name.clone(), input.clone(), &sess.parse_sess)
 575             }
 576         }
 577     })?;
 578
 579     sess.diagnostic().set_continue_after_error(true);
 580
 581     if sess.opts.debugging_opts.ast_json_noexpand {
 582         println!("{}", json::as_json(&krate));
 583     }
 584
 585     if sess.opts.debugging_opts.input_stats {
 586         println!("Lines of code:             {}", sess.codemap().count_lines());
 587         println!("Pre-expansion node count:  {}", count_nodes(&krate));
 588     }
 589
 590     if let Some(ref s) = sess.opts.debugging_opts.show_span {
 591         syntax::show_span::run(sess.diagnostic(), s, &krate);
 592     }
 593
 594     if sess.opts.debugging_opts.hir_stats {
 595         hir_stats::print_ast_stats(&krate, "PRE EXPANSION AST STATS");
 596     }
 597
 598     Ok(krate)
 599 }
 600
 601 fn count_nodes(krate: &ast::Crate) -> usize {
 602     let mut counter = NodeCounter::new();
 603     visit::walk_crate(&mut counter, krate);
 604     counter.count
 605 }
 606
 607 // For continuing compilation after a parsed crate has been
 608 // modified
 609
 610 pub struct ExpansionResult {
 611     pub expanded_crate: ast::Crate,
 612     pub defs: hir_map::Definitions,
 613     pub analysis: ty::CrateAnalysis,
 614     pub resolutions: Resolutions,
 615     pub hir_forest: hir_map::Forest,
 616 }
 617
 618 /// Run the "early phases" of the compiler: initial `cfg` processing,
 619 /// loading compiler plugins (including those from `addl_plugins`),
 620 /// syntax expansion, secondary `cfg` expansion, synthesis of a test
 621 /// harness if one is to be provided, injection of a dependency on the
 622 /// standard library and prelude, and name resolution.
 623 ///
 624 /// Returns `None` if we're aborting after handling -W help.
 625 pub fn phase_2_configure_and_expand<F>(sess: &Session,
 626                                        cstore: &CStore,
 627                                        krate: ast::Crate,
 628                                        registry: Option<Registry>,
 629                                        crate_name: &str,
 630                                        addl_plugins: Option<Vec<String>>,
 631                                        make_glob_map: MakeGlobMap,
 632                                        after_expand: F)
 633                                        -> Result<ExpansionResult, CompileIncomplete>
 634     where F: FnOnce(&ast::Crate) -> CompileResult,
 635 {
 636     let time_passes = sess.time_passes();
 637
 638     let (mut krate, features) = syntax::config::features(krate, &sess.parse_sess, sess.opts.test);
 639     // these need to be set "early" so that expansion sees `quote` if enabled.
 640     *sess.features.borrow_mut() = features;
 641
 642     *sess.crate_types.borrow_mut() = collect_crate_types(sess, &krate.attrs);
 643
 644     let disambiguator = compute_crate_disambiguator(sess);
 645     *sess.crate_disambiguator.borrow_mut() = Some(disambiguator);
 646     rustc_incremental::prepare_session_directory(
 647         sess,
 648         &crate_name,
 649         disambiguator,
 650     );
 651
 652     let dep_graph = if sess.opts.build_dep_graph() {
 653         let prev_dep_graph = time(time_passes, "load prev dep-graph", || {
 654             rustc_incremental::load_dep_graph(sess)
 655         });
 656
 657         DepGraph::new(prev_dep_graph)
 658     } else {
 659         DepGraph::new_disabled()
 660     };
 661
 662     time(time_passes, "recursion limit", || {
 663         middle::recursion_limit::update_limits(sess, &krate);
 664     });
 665
 666     krate = time(time_passes, "crate injection", || {
 667         let alt_std_name = sess.opts.alt_std_name.clone();
 668         syntax::std_inject::maybe_inject_crates_ref(krate, alt_std_name)
 669     });
 670
 671     let mut addl_plugins = Some(addl_plugins);
 672     let registrars = time(time_passes, "plugin loading", || {
 673         plugin::load::load_plugins(sess,
 674                                    &cstore,
 675                                    &krate,
 676                                    crate_name,
 677                                    addl_plugins.take().unwrap())
 678     });
 679
 680     let mut registry = registry.unwrap_or(Registry::new(sess, krate.span));
 681
 682     time(time_passes, "plugin registration", || {
 683         if sess.features.borrow().rustc_diagnostic_macros {
 684             registry.register_macro("__diagnostic_used",
 685                                     diagnostics::plugin::expand_diagnostic_used);
 686             registry.register_macro("__register_diagnostic",
 687                                     diagnostics::plugin::expand_register_diagnostic);
 688             registry.register_macro("__build_diagnostic_array",
 689                                     diagnostics::plugin::expand_build_diagnostic_array);
 690         }
 691
 692         for registrar in registrars {
 693             registry.args_hidden = Some(registrar.args);
 694             (registrar.fun)(&mut registry);
 695         }
 696     });
 697
 698     let whitelisted_legacy_custom_derives = registry.take_whitelisted_custom_derives();
 699     let Registry { syntax_exts, early_lint_passes, late_lint_passes, lint_groups,
 700                    llvm_passes, attributes, .. } = registry;
 701
 702     sess.track_errors(|| {
 703         let mut ls = sess.lint_store.borrow_mut();
 704         for pass in early_lint_passes {
 705             ls.register_early_pass(Some(sess), true, pass);
 706         }
 707         for pass in late_lint_passes {
 708             ls.register_late_pass(Some(sess), true, pass);
 709         }
 710
 711         for (name, to) in lint_groups {
 712             ls.register_group(Some(sess), true, name, to);
 713         }
 714
 715         *sess.plugin_llvm_passes.borrow_mut() = llvm_passes;
 716         *sess.plugin_attributes.borrow_mut() = attributes.clone();
 717     })?;
 718
 719     // Lint plugins are registered; now we can process command line flags.
 720     if sess.opts.describe_lints {
 721         super::describe_lints(&sess.lint_store.borrow(), true);
 722         return Err(CompileIncomplete::Stopped);
 723     }
 724
 725     // Currently, we ignore the name resolution data structures for the purposes of dependency
 726     // tracking. Instead we will run name resolution and include its output in the hash of each
 727     // item, much like we do for macro expansion. In other words, the hash reflects not just
 728     // its contents but the results of name resolution on those contents. Hopefully we'll push
 729     // this back at some point.
 730     let mut crate_loader = CrateLoader::new(sess, &cstore, crate_name);
 731     let resolver_arenas = Resolver::arenas();
 732     let mut resolver = Resolver::new(sess,
 733                                      cstore,
 734                                      &krate,
 735                                      crate_name,
 736                                      make_glob_map,
 737                                      &mut crate_loader,
 738                                      &resolver_arenas);
 739     resolver.whitelisted_legacy_custom_derives = whitelisted_legacy_custom_derives;
 740     syntax_ext::register_builtins(&mut resolver, syntax_exts, sess.features.borrow().quote);
 741
 742     krate = time(time_passes, "expansion", || {
 743         // Windows dlls do not have rpaths, so they don't know how to find their
 744         // dependencies. It's up to us to tell the system where to find all the
 745         // dependent dlls. Note that this uses cfg!(windows) as opposed to
 746         // targ_cfg because syntax extensions are always loaded for the host
 747         // compiler, not for the target.
 748         //
 749         // This is somewhat of an inherently racy operation, however, as
 750         // multiple threads calling this function could possibly continue
 751         // extending PATH far beyond what it should. To solve this for now we
 752         // just don't add any new elements to PATH which are already there
 753         // within PATH. This is basically a targeted fix at #17360 for rustdoc
 754         // which runs rustc in parallel but has been seen (#33844) to cause
 755         // problems with PATH becoming too long.
 756         let mut old_path = OsString::new();
 757         if cfg!(windows) {
 758             old_path = env::var_os("PATH").unwrap_or(old_path);
 759             let mut new_path = sess.host_filesearch(PathKind::All)
 760                                    .get_dylib_search_paths();
 761             for path in env::split_paths(&old_path) {
 762                 if !new_path.contains(&path) {
 763                     new_path.push(path);
 764                 }
 765             }
 766             env::set_var("PATH",
 767                 &env::join_paths(new_path.iter()
 768                                          .filter(|p| env::join_paths(iter::once(p)).is_ok()))
 769                      .unwrap());
 770         }
 771         let features = sess.features.borrow();
 772         let cfg = syntax::ext::expand::ExpansionConfig {
 773             features: Some(&features),
 774             recursion_limit: sess.recursion_limit.get(),
 775             trace_mac: sess.opts.debugging_opts.trace_macros,
 776             should_test: sess.opts.test,
 777             ..syntax::ext::expand::ExpansionConfig::default(crate_name.to_string())
 778         };
 779
 780         let mut ecx = ExtCtxt::new(&sess.parse_sess, cfg, &mut resolver);
 781         let err_count = ecx.parse_sess.span_diagnostic.err_count();
 782
 783         let krate = ecx.monotonic_expander().expand_crate(krate);
 784
 785         ecx.check_unused_macros();
 786
 787         let mut missing_fragment_specifiers: Vec<_> =
 788             ecx.parse_sess.missing_fragment_specifiers.borrow().iter().cloned().collect();
 789         missing_fragment_specifiers.sort();
 790         for span in missing_fragment_specifiers {
 791             let lint = lint::builtin::MISSING_FRAGMENT_SPECIFIER;
 792             let msg = "missing fragment specifier";
 793             sess.buffer_lint(lint, ast::CRATE_NODE_ID, span, msg);
 794         }
 795         if ecx.parse_sess.span_diagnostic.err_count() - ecx.resolve_err_count > err_count {
 796             ecx.parse_sess.span_diagnostic.abort_if_errors();
 797         }
 798         if cfg!(windows) {
 799             env::set_var("PATH", &old_path);
 800         }
 801         krate
 802     });
 803
 804     krate = time(time_passes, "maybe building test harness", || {
 805         syntax::test::modify_for_testing(&sess.parse_sess,
 806                                          &mut resolver,
 807                                          sess.opts.test,
 808                                          krate,
 809                                          sess.diagnostic())
 810     });
 811
 812     // If we're in rustdoc we're always compiling as an rlib, but that'll trip a
 813     // bunch of checks in the `modify` function below. For now just skip this
 814     // step entirely if we're rustdoc as it's not too useful anyway.
 815     if !sess.opts.actually_rustdoc {
 816         krate = time(time_passes, "maybe creating a macro crate", || {
 817             let crate_types = sess.crate_types.borrow();
 818             let num_crate_types = crate_types.len();
 819             let is_proc_macro_crate = crate_types.contains(&config::CrateTypeProcMacro);
 820             let is_test_crate = sess.opts.test;
 821             syntax_ext::proc_macro_registrar::modify(&sess.parse_sess,
 822                                                      &mut resolver,
 823                                                      krate,
 824                                                      is_proc_macro_crate,
 825                                                      is_test_crate,
 826                                                      num_crate_types,
 827                                                      sess.diagnostic())
 828         });
 829     }
 830
 831     krate = time(time_passes, "creating allocators", || {
 832         allocator::expand::modify(&sess.parse_sess,
 833                                   &mut resolver,
 834                                   krate,
 835                                   sess.diagnostic())
 836     });
 837
 838     after_expand(&krate)?;
 839
 840     if sess.opts.debugging_opts.input_stats {
 841         println!("Post-expansion node count: {}", count_nodes(&krate));
 842     }
 843
 844     if sess.opts.debugging_opts.hir_stats {
 845         hir_stats::print_ast_stats(&krate, "POST EXPANSION AST STATS");
 846     }
 847
 848     if sess.opts.debugging_opts.ast_json {
 849         println!("{}", json::as_json(&krate));
 850     }
 851
 852     time(time_passes,
 853          "checking for inline asm in case the target doesn't support it",
 854          || no_asm::check_crate(sess, &krate));
 855
 856     time(time_passes,
 857          "AST validation",
 858          || ast_validation::check_crate(sess, &krate));
 859
 860     time(time_passes, "name resolution", || -> CompileResult {
 861         resolver.resolve_crate(&krate);
 862         Ok(())
 863     })?;
 864
 865     if resolver.found_unresolved_macro {
 866         sess.parse_sess.span_diagnostic.abort_if_errors();
 867     }
 868
 869     // Needs to go *after* expansion to be able to check the results of macro expansion.
 870     time(time_passes, "complete gated feature checking", || {
 871         sess.track_errors(|| {
 872             syntax::feature_gate::check_crate(&krate,
 873                                               &sess.parse_sess,
 874                                               &sess.features.borrow(),
 875                                               &attributes,
 876                                               sess.opts.unstable_features);
 877         })
 878     })?;
 879
 880     // Lower ast -> hir.
 881     let hir_forest = time(time_passes, "lowering ast -> hir", || {
 882         let hir_crate = lower_crate(sess, cstore, &dep_graph, &krate, &mut resolver);
 883
 884         if sess.opts.debugging_opts.hir_stats {
 885             hir_stats::print_hir_stats(&hir_crate);
 886         }
 887
 888         hir_map::Forest::new(hir_crate, &dep_graph)
 889     });
 890
 891     time(time_passes,
 892          "early lint checks",
 893          || lint::check_ast_crate(sess, &krate));
 894
 895     // Discard hygiene data, which isn't required after lowering to HIR.
 896     if !keep_hygiene_data(sess) {
 897         syntax::ext::hygiene::clear_markings();
 898     }
 899
 900     Ok(ExpansionResult {
 901         expanded_crate: krate,
 902         defs: resolver.definitions,
 903         analysis: ty::CrateAnalysis {
 904             access_levels: Rc::new(AccessLevels::default()),
 905             name: crate_name.to_string(),
 906             glob_map: if resolver.make_glob_map { Some(resolver.glob_map) } else { None },
 907         },
 908         resolutions: Resolutions {
 909             freevars: resolver.freevars,
 910             export_map: resolver.export_map,
 911             trait_map: resolver.trait_map,
 912             maybe_unused_trait_imports: resolver.maybe_unused_trait_imports,
 913             maybe_unused_extern_crates: resolver.maybe_unused_extern_crates,
 914         },
 915         hir_forest,
 916     })
 917 }
 918
 919 pub fn default_provide(providers: &mut ty::maps::Providers) {
 920     borrowck::provide(providers);
 921     mir::provide(providers);
 922     reachable::provide(providers);
 923     rustc_privacy::provide(providers);
 924     DefaultTransCrate::provide(providers);
 925     typeck::provide(providers);
 926     ty::provide(providers);
 927     traits::provide(providers);
 928     reachable::provide(providers);
 929     rustc_const_eval::provide(providers);
 930     rustc_passes::provide(providers);
 931     middle::region::provide(providers);
 932     cstore::provide(providers);
 933     lint::provide(providers);
 934 }
 935
 936 pub fn default_provide_extern(providers: &mut ty::maps::Providers) {
 937     cstore::provide_extern(providers);
 938     DefaultTransCrate::provide_extern(providers);
 939 }
 940
 941 /// Run the resolution, typechecking, region checking and other
 942 /// miscellaneous analysis passes on the crate. Return various
 943 /// structures carrying the results of the analysis.
 944 pub fn phase_3_run_analysis_passes<'tcx, F, R>(control: &CompileController,
 945                                                sess: &'tcx Session,
 946                                                cstore: &'tcx CrateStore,
 947                                                hir_map: hir_map::Map<'tcx>,
 948                                                mut analysis: ty::CrateAnalysis,
 949                                                resolutions: Resolutions,
 950                                                arena: &'tcx DroplessArena,
 951                                                arenas: &'tcx GlobalArenas<'tcx>,
 952                                                name: &str,
 953                                                output_filenames: &OutputFilenames,
 954                                                f: F)
 955                                                -> Result<R, CompileIncomplete>
 956     where F: for<'a> FnOnce(TyCtxt<'a, 'tcx, 'tcx>,
 957                             ty::CrateAnalysis,
 958                             mpsc::Receiver<Box<Any + Send>>,
 959                             CompileResult) -> R
 960 {
 961     macro_rules! try_with_f {
 962         ($e: expr, ($($t:tt)*)) => {
 963             match $e {
 964                 Ok(x) => x,
 965                 Err(x) => {
 966                     f($($t)*, Err(x));
 967                     return Err(x);
 968                 }
 969             }
 970         }
 971     }
 972
 973     let time_passes = sess.time_passes();
 974
 975     let query_result_on_disk_cache = time(time_passes,
 976         "load query result cache",
 977         || rustc_incremental::load_query_result_cache(sess));
 978
 979     let named_region_map = time(time_passes,
 980                                 "lifetime resolution",
 981                                 || middle::resolve_lifetime::krate(sess, cstore, &hir_map))?;
 982
 983     time(time_passes,
 984          "looking for entry point",
 985          || middle::entry::find_entry_point(sess, &hir_map));
 986
 987     sess.plugin_registrar_fn.set(time(time_passes, "looking for plugin registrar", || {
 988         plugin::build::find_plugin_registrar(sess.diagnostic(), &hir_map)
 989     }));
 990     sess.derive_registrar_fn.set(derive_registrar::find(&hir_map));
 991
 992     time(time_passes,
 993          "loop checking",
 994          || loops::check_crate(sess, &hir_map));
 995
 996     time(time_passes,
 997               "static item recursion checking",
 998               || static_recursion::check_crate(sess, &hir_map))?;
 999
1000     let mut local_providers = ty::maps::Providers::default();
1001     default_provide(&mut local_providers);
1002     (control.provide)(&mut local_providers);
1003
1004     let mut extern_providers = local_providers;
1005     default_provide_extern(&mut extern_providers);
1006     (control.provide_extern)(&mut extern_providers);
1007
1008     let (tx, rx) = mpsc::channel();
1009
1010     TyCtxt::create_and_enter(sess,
1011                              cstore,
1012                              local_providers,
1013                              extern_providers,
1014                              arenas,
1015                              arena,
1016                              resolutions,
1017                              named_region_map,
1018                              hir_map,
1019                              query_result_on_disk_cache,
1020                              name,
1021                              tx,
1022                              output_filenames,
1023                              |tcx| {
1024         // Do some initialization of the DepGraph that can only be done with the
1025         // tcx available.
1026         rustc_incremental::dep_graph_tcx_init(tcx);
1027
1028         time(time_passes,
1029              "stability checking",
1030              || stability::check_unstable_api_usage(tcx));
1031
1032         // passes are timed inside typeck
1033         try_with_f!(typeck::check_crate(tcx), (tcx, analysis, rx));
1034
1035         time(time_passes,
1036              "const checking",
1037              || consts::check_crate(tcx));
1038
1039         analysis.access_levels =
1040             time(time_passes, "privacy checking", || rustc_privacy::check_crate(tcx));
1041
1042         time(time_passes,
1043              "intrinsic checking",
1044              || middle::intrinsicck::check_crate(tcx));
1045
1046         time(time_passes,
1047              "match checking",
1048              || check_match::check_crate(tcx));
1049
1050         // this must run before MIR dump, because
1051         // "not all control paths return a value" is reported here.
1052         //
1053         // maybe move the check to a MIR pass?
1054         time(time_passes,
1055              "liveness checking",
1056              || middle::liveness::check_crate(tcx));
1057
1058         time(time_passes,
1059              "borrow checking",
1060              || borrowck::check_crate(tcx));
1061
1062         time(time_passes,
1063              "MIR borrow checking",
1064              || for def_id in tcx.body_owners() { tcx.mir_borrowck(def_id) });
1065
1066         time(time_passes,
1067              "MIR effect checking",
1068              || for def_id in tcx.body_owners() {
1069                  mir::transform::check_unsafety::check_unsafety(tcx, def_id)
1070              });
1071         // Avoid overwhelming user with errors if type checking failed.
1072         // I'm not sure how helpful this is, to be honest, but it avoids
1073         // a
1074         // lot of annoying errors in the compile-fail tests (basically,
1075         // lint warnings and so on -- kindck used to do this abort, but
1076         // kindck is gone now). -nmatsakis
1077         if sess.err_count() > 0 {
1078             return Ok(f(tcx, analysis, rx, sess.compile_status()));
1079         }
1080
1081         time(time_passes, "death checking", || middle::dead::check_crate(tcx));
1082
1083         time(time_passes, "unused lib feature checking", || {
1084             stability::check_unused_or_stable_features(tcx)
1085         });
1086
1087         time(time_passes, "lint checking", || lint::check_crate(tcx));
1088
1089         return Ok(f(tcx, analysis, rx, tcx.sess.compile_status()));
1090     })
1091 }
1092
1093 /// Run the translation phase to LLVM, after which the AST and analysis can
1094 /// be discarded.
1095 pub fn phase_4_translate_to_llvm<'a, 'tcx, Trans: TransCrate>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
1096                                            rx: mpsc::Receiver<Box<Any + Send>>)
1097                                            -> <Trans as TransCrate>::OngoingCrateTranslation {
1098     let time_passes = tcx.sess.time_passes();
1099
1100     time(time_passes,
1101          "resolving dependency formats",
1102          || ::rustc::middle::dependency_format::calculate(tcx));
1103
1104     let translation =
1105         time(time_passes, "translation", move || {
1106             Trans::trans_crate(tcx, rx)
1107         });
1108     if tcx.sess.profile_queries() {
1109         profile::dump("profile_queries".to_string())
1110     }
1111
1112     translation
1113 }
1114
1115 /// Run LLVM itself, producing a bitcode file, assembly file or object file
1116 /// as a side effect.
1117 pub fn phase_5_run_llvm_passes<Trans: TransCrate>(sess: &Session,
1118                                dep_graph: &DepGraph,
1119                                trans: <Trans as TransCrate>::OngoingCrateTranslation)
1120                                -> (CompileResult, <Trans as TransCrate>::TranslatedCrate) {
1121     let trans = Trans::join_trans(trans, sess, dep_graph);
1122
1123     if sess.opts.debugging_opts.incremental_info {
1124         Trans::dump_incremental_data(&trans);
1125     }
1126
1127     time(sess.time_passes(),
1128          "serialize work products",
1129          move || rustc_incremental::save_work_products(sess, dep_graph));
1130
1131     (sess.compile_status(), trans)
1132 }
1133
1134 fn escape_dep_filename(filename: &str) -> String {
1135     // Apparently clang and gcc *only* escape spaces:
1136     // http://llvm.org/klaus/clang/commit/9d50634cfc268ecc9a7250226dd5ca0e945240d4
1137     filename.replace(" ", "\\ ")
1138 }
1139
1140 fn write_out_deps(sess: &Session, outputs: &OutputFilenames, crate_name: &str) {
1141     let mut out_filenames = Vec::new();
1142     for output_type in sess.opts.output_types.keys() {
1143         let file = outputs.path(*output_type);
1144         match *output_type {
1145             OutputType::Exe => {
1146                 for output in sess.crate_types.borrow().iter() {
1147                     let p = ::rustc_trans_utils::link::filename_for_input(
1148                         sess,
1149                         *output,
1150                         crate_name,
1151                         outputs
1152                     );
1153                     out_filenames.push(p);
1154                 }
1155             }
1156             _ => {
1157                 out_filenames.push(file);
1158             }
1159         }
1160     }
1161
1162     // Write out dependency rules to the dep-info file if requested
1163     if !sess.opts.output_types.contains_key(&OutputType::DepInfo) {
1164         return;
1165     }
1166     let deps_filename = outputs.path(OutputType::DepInfo);
1167
1168     let result =
1169         (|| -> io::Result<()> {
1170             // Build a list of files used to compile the output and
1171             // write Makefile-compatible dependency rules
1172             let files: Vec<String> = sess.codemap()
1173                                          .files()
1174                                          .iter()
1175                                          .filter(|fmap| fmap.is_real_file())
1176                                          .filter(|fmap| !fmap.is_imported())
1177                                          .map(|fmap| escape_dep_filename(&fmap.name))
1178                                          .collect();
1179             let mut file = fs::File::create(&deps_filename)?;
1180             for path in &out_filenames {
1181                 write!(file, "{}: {}\n\n", path.display(), files.join(" "))?;
1182             }
1183
1184             // Emit a fake target for each input file to the compilation. This
1185             // prevents `make` from spitting out an error if a file is later
1186             // deleted. For more info see #28735
1187             for path in files {
1188                 writeln!(file, "{}:", path)?;
1189             }
1190             Ok(())
1191         })();
1192
1193     match result {
1194         Ok(()) => {}
1195         Err(e) => {
1196             sess.fatal(&format!("error writing dependencies to `{}`: {}",
1197                                 deps_filename.display(),
1198                                 e));
1199         }
1200     }
1201 }
1202
1203 pub fn collect_crate_types(session: &Session, attrs: &[ast::Attribute]) -> Vec<config::CrateType> {
1204     // Unconditionally collect crate types from attributes to make them used
1205     let attr_types: Vec<config::CrateType> =
1206         attrs.iter()
1207              .filter_map(|a| {
1208                  if a.check_name("crate_type") {
1209                      match a.value_str() {
1210                          Some(ref n) if *n == "rlib" => {
1211                              Some(config::CrateTypeRlib)
1212                          }
1213                          Some(ref n) if *n == "dylib" => {
1214                              Some(config::CrateTypeDylib)
1215                          }
1216                          Some(ref n) if *n == "cdylib" => {
1217                              Some(config::CrateTypeCdylib)
1218                          }
1219                          Some(ref n) if *n == "lib" => {
1220                              Some(config::default_lib_output())
1221                          }
1222                          Some(ref n) if *n == "staticlib" => {
1223                              Some(config::CrateTypeStaticlib)
1224                          }
1225                          Some(ref n) if *n == "proc-macro" => {
1226                              Some(config::CrateTypeProcMacro)
1227                          }
1228                          Some(ref n) if *n == "bin" => Some(config::CrateTypeExecutable),
1229                          Some(_) => {
1230                              session.buffer_lint(lint::builtin::UNKNOWN_CRATE_TYPES,
1231                                                  ast::CRATE_NODE_ID,
1232                                                  a.span,
1233                                                  "invalid `crate_type` value");
1234                              None
1235                          }
1236                          _ => {
1237                              session.struct_span_err(a.span, "`crate_type` requires a value")
1238                                  .note("for example: `#![crate_type=\"lib\"]`")
1239                                  .emit();
1240                              None
1241                          }
1242                      }
1243                  } else {
1244                      None
1245                  }
1246              })
1247              .collect();
1248
1249     // If we're generating a test executable, then ignore all other output
1250     // styles at all other locations
1251     if session.opts.test {
1252         return vec![config::CrateTypeExecutable];
1253     }
1254
1255     // Only check command line flags if present. If no types are specified by
1256     // command line, then reuse the empty `base` Vec to hold the types that
1257     // will be found in crate attributes.
1258     let mut base = session.opts.crate_types.clone();
1259     if base.is_empty() {
1260         base.extend(attr_types);
1261         if base.is_empty() {
1262             base.push(::rustc_trans_utils::link::default_output_for_target(session));
1263         }
1264         base.sort();
1265         base.dedup();
1266     }
1267
1268     base.into_iter()
1269         .filter(|crate_type| {
1270             let res = !::rustc_trans_utils::link::invalid_output_for_target(session, *crate_type);
1271
1272             if !res {
1273                 session.warn(&format!("dropping unsupported crate type `{}` for target `{}`",
1274                                       *crate_type,
1275                                       session.opts.target_triple));
1276             }
1277
1278             res
1279         })
1280         .collect()
1281 }
1282
1283 pub fn compute_crate_disambiguator(session: &Session) -> CrateDisambiguator {
1284     use std::hash::Hasher;
1285
1286     // The crate_disambiguator is a 128 bit hash. The disambiguator is fed
1287     // into various other hashes quite a bit (symbol hashes, incr. comp. hashes,
1288     // debuginfo type IDs, etc), so we don't want it to be too wide. 128 bits
1289     // should still be safe enough to avoid collisions in practice.
1290     let mut hasher = StableHasher::<Fingerprint>::new();
1291
1292     let mut metadata = session.opts.cg.metadata.clone();
1293     // We don't want the crate_disambiguator to dependent on the order
1294     // -C metadata arguments, so sort them:
1295     metadata.sort();
1296     // Every distinct -C metadata value is only incorporated once:
1297     metadata.dedup();
1298
1299     hasher.write(b"metadata");
1300     for s in &metadata {
1301         // Also incorporate the length of a metadata string, so that we generate
1302         // different values for `-Cmetadata=ab -Cmetadata=c` and
1303         // `-Cmetadata=a -Cmetadata=bc`
1304         hasher.write_usize(s.len());
1305         hasher.write(s.as_bytes());
1306     }
1307
1308     // Also incorporate crate type, so that we don't get symbol conflicts when
1309     // linking against a library of the same name, if this is an executable.
1310     let is_exe = session.crate_types.borrow().contains(&config::CrateTypeExecutable);
1311     hasher.write(if is_exe { b"exe" } else { b"lib" });
1312
1313     CrateDisambiguator::from(hasher.finish())
1314
1315 }
1316
1317 pub fn build_output_filenames(input: &Input,
1318                               odir: &Option<PathBuf>,
1319                               ofile: &Option<PathBuf>,
1320                               attrs: &[ast::Attribute],
1321                               sess: &Session)
1322                               -> OutputFilenames {
1323     match *ofile {
1324         None => {
1325             // "-" as input file will cause the parser to read from stdin so we
1326             // have to make up a name
1327             // We want to toss everything after the final '.'
1328             let dirpath = match *odir {
1329                 Some(ref d) => d.clone(),
1330                 None => PathBuf::new(),
1331             };
1332
1333             // If a crate name is present, we use it as the link name
1334             let stem = sess.opts
1335                            .crate_name
1336                            .clone()
1337                            .or_else(|| attr::find_crate_name(attrs).map(|n| n.to_string()))
1338                            .unwrap_or(input.filestem());
1339
1340             OutputFilenames {
1341                 out_directory: dirpath,
1342                 out_filestem: stem,
1343                 single_output_file: None,
1344                 extra: sess.opts.cg.extra_filename.clone(),
1345                 outputs: sess.opts.output_types.clone(),
1346             }
1347         }
1348
1349         Some(ref out_file) => {
1350             let unnamed_output_types = sess.opts
1351                                            .output_types
1352                                            .values()
1353                                            .filter(|a| a.is_none())
1354                                            .count();
1355             let ofile = if unnamed_output_types > 1 {
1356                 sess.warn("due to multiple output types requested, the explicitly specified \
1357                            output file name will be adapted for each output type");
1358                 None
1359             } else {
1360                 Some(out_file.clone())
1361             };
1362             if *odir != None {
1363                 sess.warn("ignoring --out-dir flag due to -o flag.");
1364             }
1365
1366             let cur_dir = Path::new("");
1367
1368             OutputFilenames {
1369                 out_directory: out_file.parent().unwrap_or(cur_dir).to_path_buf(),
1370                 out_filestem: out_file.file_stem()
1371                                       .unwrap_or(OsStr::new(""))
1372                                       .to_str()
1373                                       .unwrap()
1374                                       .to_string(),
1375                 single_output_file: ofile,
1376                 extra: sess.opts.cg.extra_filename.clone(),
1377                 outputs: sess.opts.output_types.clone(),
1378             }
1379         }
1380     }
1381 }