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, resolve_lifetime};
  23 use rustc::middle::cstore::CrateStore;
  24 use rustc::middle::privacy::AccessLevels;
  25 use rustc::ty::{self, TyCtxt, Resolutions, AllArenas};
  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, ResolverArenas};
  32 use rustc_metadata::creader::CrateLoader;
  33 use rustc_metadata::cstore::{self, CStore};
  34 use rustc_trans_utils::trans_crate::TransCrate;
  35 use rustc_typeck as typeck;
  36 use rustc_privacy;
  37 use rustc_plugin::registry::Registry;
  38 use rustc_plugin as plugin;
  39 use rustc_passes::{self, ast_validation, loops, consts, static_recursion, hir_stats};
  40 use rustc_const_eval::{self, check_match};
  41 use super::Compilation;
  42
  43 use serialize::json;
  44
  45 use std::any::Any;
  46 use std::env;
  47 use std::ffi::{OsString, OsStr};
  48 use std::fs;
  49 use std::io::{self, Write};
  50 use std::iter;
  51 use std::path::{Path, PathBuf};
  52 use std::rc::Rc;
  53 use std::sync::mpsc;
  54 use syntax::{self, ast, attr, diagnostics, visit};
  55 use syntax::ext::base::ExtCtxt;
  56 use syntax::fold::Folder;
  57 use syntax::parse::{self, PResult};
  58 use syntax::util::node_count::NodeCounter;
  59 use syntax_pos::FileName;
  60 use syntax_ext;
  61
  62 use derive_registrar;
  63 use pretty::ReplaceBodyWithLoop;
  64
  65 use profile;
  66
  67 pub fn compile_input(trans: Box<TransCrate>,
  68                      sess: &Session,
  69                      cstore: &CStore,
  70                      input_path: &Option<PathBuf>,
  71                      input: &Input,
  72                      outdir: &Option<PathBuf>,
  73                      output: &Option<PathBuf>,
  74                      addl_plugins: Option<Vec<String>>,
  75                      control: &CompileController) -> CompileResult {
  76     macro_rules! controller_entry_point {
  77         ($point: ident, $tsess: expr, $make_state: expr, $phase_result: expr) => {{
  78             let state = &mut $make_state;
  79             let phase_result: &CompileResult = &$phase_result;
  80             if phase_result.is_ok() || control.$point.run_callback_on_error {
  81                 (control.$point.callback)(state);
  82             }
  83
  84             if control.$point.stop == Compilation::Stop {
  85                 // FIXME: shouldn't this return Err(CompileIncomplete::Stopped)
  86                 // if there are no errors?
  87                 return $tsess.compile_status();
  88             }
  89         }}
  90     }
  91
  92     if sess.profile_queries() {
  93         profile::begin();
  94     }
  95
  96     // We need nested scopes here, because the intermediate results can keep
  97     // large chunks of memory alive and we want to free them as soon as
  98     // possible to keep the peak memory usage low
  99     let (outputs, ongoing_trans, dep_graph) = {
 100         let krate = match phase_1_parse_input(control, sess, input) {
 101             Ok(krate) => krate,
 102             Err(mut parse_error) => {
 103                 parse_error.emit();
 104                 return Err(CompileIncomplete::Errored(ErrorReported));
 105             }
 106         };
 107
 108         let (krate, registry) = {
 109             let mut compile_state = CompileState::state_after_parse(input,
 110                                                                     sess,
 111                                                                     outdir,
 112                                                                     output,
 113                                                                     krate,
 114                                                                     &cstore);
 115             controller_entry_point!(after_parse,
 116                                     sess,
 117                                     compile_state,
 118                                     Ok(()));
 119
 120             (compile_state.krate.unwrap(), compile_state.registry)
 121         };
 122
 123         let outputs = build_output_filenames(input, outdir, output, &krate.attrs, sess);
 124         let crate_name =
 125             ::rustc_trans_utils::link::find_crate_name(Some(sess), &krate.attrs, input);
 126         let ExpansionResult { expanded_crate, defs, analysis, resolutions, mut hir_forest } = {
 127             phase_2_configure_and_expand(
 128                 sess,
 129                 &cstore,
 130                 krate,
 131                 registry,
 132                 &crate_name,
 133                 addl_plugins,
 134                 control.make_glob_map,
 135                 |expanded_crate| {
 136                     let mut state = CompileState::state_after_expand(
 137                         input, sess, outdir, output, &cstore, expanded_crate, &crate_name,
 138                     );
 139                     controller_entry_point!(after_expand, sess, state, Ok(()));
 140                     Ok(())
 141                 }
 142             )?
 143         };
 144
 145         let output_paths = generated_output_paths(sess, &outputs, output.is_some(), &crate_name);
 146
 147         // Ensure the source file isn't accidentally overwritten during compilation.
 148         if let Some(ref input_path) = *input_path {
 149             if sess.opts.will_create_output_file() {
 150                 if output_contains_path(&output_paths, input_path) {
 151                     sess.err(&format!(
 152                         "the input file \"{}\" would be overwritten by the generated \
 153                         executable",
 154                         input_path.display()));
 155                     return Err(CompileIncomplete::Stopped);
 156                 }
 157                 if let Some(dir_path) = output_conflicts_with_dir(&output_paths) {
 158                     sess.err(&format!(
 159                         "the generated executable for the input file \"{}\" conflicts with the \
 160                         existing directory \"{}\"",
 161                         input_path.display(), dir_path.display()));
 162                     return Err(CompileIncomplete::Stopped);
 163                 }
 164             }
 165         }
 166
 167         write_out_deps(sess, &outputs, &output_paths);
 168         if sess.opts.output_types.contains_key(&OutputType::DepInfo) &&
 169             sess.opts.output_types.keys().count() == 1 {
 170             return Ok(())
 171         }
 172
 173         if let &Some(ref dir) = outdir {
 174             if fs::create_dir_all(dir).is_err() {
 175                 sess.err("failed to find or create the directory specified by --out-dir");
 176                 return Err(CompileIncomplete::Stopped);
 177             }
 178         }
 179
 180         let arenas = AllArenas::new();
 181
 182         // Construct the HIR map
 183         let hir_map = time(sess.time_passes(),
 184                            "indexing hir",
 185                            || hir_map::map_crate(sess, cstore, &mut hir_forest, &defs));
 186
 187         {
 188             hir_map.dep_graph.assert_ignored();
 189             controller_entry_point!(after_hir_lowering,
 190                                     sess,
 191                                     CompileState::state_after_hir_lowering(input,
 192                                                                   sess,
 193                                                                   outdir,
 194                                                                   output,
 195                                                                   &arenas,
 196                                                                   &cstore,
 197                                                                   &hir_map,
 198                                                                   &analysis,
 199                                                                   &resolutions,
 200                                                                   &expanded_crate,
 201                                                                   &hir_map.krate(),
 202                                                                   &outputs,
 203                                                                   &crate_name),
 204                                     Ok(()));
 205         }
 206
 207         let opt_crate = if control.keep_ast {
 208             Some(&expanded_crate)
 209         } else {
 210             drop(expanded_crate);
 211             None
 212         };
 213
 214         phase_3_run_analysis_passes(&*trans,
 215                                     control,
 216                                     sess,
 217                                     cstore,
 218                                     hir_map,
 219                                     analysis,
 220                                     resolutions,
 221                                     &arenas,
 222                                     &crate_name,
 223                                     &outputs,
 224                                     |tcx, analysis, rx, result| {
 225             {
 226                 // Eventually, we will want to track plugins.
 227                 tcx.dep_graph.with_ignore(|| {
 228                     let mut state = CompileState::state_after_analysis(input,
 229                                                                        sess,
 230                                                                        outdir,
 231                                                                        output,
 232                                                                        opt_crate,
 233                                                                        tcx.hir.krate(),
 234                                                                        &analysis,
 235                                                                        tcx,
 236                                                                        &crate_name);
 237                     (control.after_analysis.callback)(&mut state);
 238                 });
 239
 240                 if control.after_analysis.stop == Compilation::Stop {
 241                     return result.and_then(|_| Err(CompileIncomplete::Stopped));
 242                 }
 243             }
 244
 245             result?;
 246
 247             if log_enabled!(::log::Level::Info) {
 248                 println!("Pre-trans");
 249                 tcx.print_debug_stats();
 250             }
 251
 252             let ongoing_trans = phase_4_translate_to_llvm(&*trans, tcx, rx);
 253
 254             if log_enabled!(::log::Level::Info) {
 255                 println!("Post-trans");
 256                 tcx.print_debug_stats();
 257             }
 258
 259             if tcx.sess.opts.output_types.contains_key(&OutputType::Mir) {
 260                 if let Err(e) = mir::transform::dump_mir::emit_mir(tcx, &outputs) {
 261                     sess.err(&format!("could not emit MIR: {}", e));
 262                     sess.abort_if_errors();
 263                 }
 264             }
 265
 266             Ok((outputs.clone(), ongoing_trans, tcx.dep_graph.clone()))
 267         })??
 268     };
 269
 270     if sess.opts.debugging_opts.print_type_sizes {
 271         sess.code_stats.borrow().print_type_sizes();
 272     }
 273
 274     trans.join_trans_and_link(ongoing_trans, sess, &dep_graph, &outputs)?;
 275
 276     if sess.opts.debugging_opts.perf_stats {
 277         sess.print_perf_stats();
 278     }
 279
 280     controller_entry_point!(
 281         compilation_done,
 282         sess,
 283         CompileState::state_when_compilation_done(input, sess, outdir, output),
 284         Ok(())
 285     );
 286
 287     Ok(())
 288 }
 289
 290 pub fn source_name(input: &Input) -> FileName {
 291     match *input {
 292         Input::File(ref ifile) => ifile.clone().into(),
 293         Input::Str { ref name, .. } => name.clone(),
 294     }
 295 }
 296
 297 /// CompileController is used to customize compilation, it allows compilation to
 298 /// be stopped and/or to call arbitrary code at various points in compilation.
 299 /// It also allows for various flags to be set to influence what information gets
 300 /// collected during compilation.
 301 ///
 302 /// This is a somewhat higher level controller than a Session - the Session
 303 /// controls what happens in each phase, whereas the CompileController controls
 304 /// whether a phase is run at all and whether other code (from outside the
 305 /// compiler) is run between phases.
 306 ///
 307 /// Note that if compilation is set to stop and a callback is provided for a
 308 /// given entry point, the callback is called before compilation is stopped.
 309 ///
 310 /// Expect more entry points to be added in the future.
 311 pub struct CompileController<'a> {
 312     pub after_parse: PhaseController<'a>,
 313     pub after_expand: PhaseController<'a>,
 314     pub after_hir_lowering: PhaseController<'a>,
 315     pub after_analysis: PhaseController<'a>,
 316     pub compilation_done: PhaseController<'a>,
 317
 318     // FIXME we probably want to group the below options together and offer a
 319     // better API, rather than this ad-hoc approach.
 320     pub make_glob_map: MakeGlobMap,
 321     // Whether the compiler should keep the ast beyond parsing.
 322     pub keep_ast: bool,
 323     // -Zcontinue-parse-after-error
 324     pub continue_parse_after_error: bool,
 325
 326     /// Allows overriding default rustc query providers,
 327     /// after `default_provide` has installed them.
 328     pub provide: Box<Fn(&mut ty::maps::Providers) + 'a>,
 329     /// Same as `provide`, but only for non-local crates,
 330     /// applied after `default_provide_extern`.
 331     pub provide_extern: Box<Fn(&mut ty::maps::Providers) + 'a>,
 332 }
 333
 334 impl<'a> CompileController<'a> {
 335     pub fn basic() -> CompileController<'a> {
 336         CompileController {
 337             after_parse: PhaseController::basic(),
 338             after_expand: PhaseController::basic(),
 339             after_hir_lowering: PhaseController::basic(),
 340             after_analysis: PhaseController::basic(),
 341             compilation_done: PhaseController::basic(),
 342             make_glob_map: MakeGlobMap::No,
 343             keep_ast: false,
 344             continue_parse_after_error: false,
 345             provide: box |_| {},
 346             provide_extern: box |_| {},
 347         }
 348     }
 349 }
 350
 351 pub struct PhaseController<'a> {
 352     pub stop: Compilation,
 353     // If true then the compiler will try to run the callback even if the phase
 354     // ends with an error. Note that this is not always possible.
 355     pub run_callback_on_error: bool,
 356     pub callback: Box<Fn(&mut CompileState) + 'a>,
 357 }
 358
 359 impl<'a> PhaseController<'a> {
 360     pub fn basic() -> PhaseController<'a> {
 361         PhaseController {
 362             stop: Compilation::Continue,
 363             run_callback_on_error: false,
 364             callback: box |_| {},
 365         }
 366     }
 367 }
 368
 369 /// State that is passed to a callback. What state is available depends on when
 370 /// during compilation the callback is made. See the various constructor methods
 371 /// (`state_*`) in the impl to see which data is provided for any given entry point.
 372 pub struct CompileState<'a, 'tcx: 'a> {
 373     pub input: &'a Input,
 374     pub session: &'tcx Session,
 375     pub krate: Option<ast::Crate>,
 376     pub registry: Option<Registry<'a>>,
 377     pub cstore: Option<&'tcx CStore>,
 378     pub crate_name: Option<&'a str>,
 379     pub output_filenames: Option<&'a OutputFilenames>,
 380     pub out_dir: Option<&'a Path>,
 381     pub out_file: Option<&'a Path>,
 382     pub arenas: Option<&'tcx AllArenas<'tcx>>,
 383     pub expanded_crate: Option<&'a ast::Crate>,
 384     pub hir_crate: Option<&'a hir::Crate>,
 385     pub hir_map: Option<&'a hir_map::Map<'tcx>>,
 386     pub resolutions: Option<&'a Resolutions>,
 387     pub analysis: Option<&'a ty::CrateAnalysis>,
 388     pub tcx: Option<TyCtxt<'a, 'tcx, 'tcx>>,
 389 }
 390
 391 impl<'a, 'tcx> CompileState<'a, 'tcx> {
 392     fn empty(input: &'a Input,
 393              session: &'tcx Session,
 394              out_dir: &'a Option<PathBuf>)
 395              -> Self {
 396         CompileState {
 397             input,
 398             session,
 399             out_dir: out_dir.as_ref().map(|s| &**s),
 400             out_file: None,
 401             arenas: None,
 402             krate: None,
 403             registry: None,
 404             cstore: None,
 405             crate_name: None,
 406             output_filenames: None,
 407             expanded_crate: None,
 408             hir_crate: None,
 409             hir_map: None,
 410             resolutions: None,
 411             analysis: None,
 412             tcx: None,
 413         }
 414     }
 415
 416     fn state_after_parse(input: &'a Input,
 417                          session: &'tcx Session,
 418                          out_dir: &'a Option<PathBuf>,
 419                          out_file: &'a Option<PathBuf>,
 420                          krate: ast::Crate,
 421                          cstore: &'tcx CStore)
 422                          -> Self {
 423         CompileState {
 424             // Initialize the registry before moving `krate`
 425             registry: Some(Registry::new(&session, krate.span)),
 426             krate: Some(krate),
 427             cstore: Some(cstore),
 428             out_file: out_file.as_ref().map(|s| &**s),
 429             ..CompileState::empty(input, session, out_dir)
 430         }
 431     }
 432
 433     fn state_after_expand(input: &'a Input,
 434                           session: &'tcx Session,
 435                           out_dir: &'a Option<PathBuf>,
 436                           out_file: &'a Option<PathBuf>,
 437                           cstore: &'tcx CStore,
 438                           expanded_crate: &'a ast::Crate,
 439                           crate_name: &'a str)
 440                           -> Self {
 441         CompileState {
 442             crate_name: Some(crate_name),
 443             cstore: Some(cstore),
 444             expanded_crate: Some(expanded_crate),
 445             out_file: out_file.as_ref().map(|s| &**s),
 446             ..CompileState::empty(input, session, out_dir)
 447         }
 448     }
 449
 450     fn state_after_hir_lowering(input: &'a Input,
 451                                 session: &'tcx Session,
 452                                 out_dir: &'a Option<PathBuf>,
 453                                 out_file: &'a Option<PathBuf>,
 454                                 arenas: &'tcx AllArenas<'tcx>,
 455                                 cstore: &'tcx CStore,
 456                                 hir_map: &'a hir_map::Map<'tcx>,
 457                                 analysis: &'a ty::CrateAnalysis,
 458                                 resolutions: &'a Resolutions,
 459                                 krate: &'a ast::Crate,
 460                                 hir_crate: &'a hir::Crate,
 461                                 output_filenames: &'a OutputFilenames,
 462                                 crate_name: &'a str)
 463                                 -> Self {
 464         CompileState {
 465             crate_name: Some(crate_name),
 466             arenas: Some(arenas),
 467             cstore: Some(cstore),
 468             hir_map: Some(hir_map),
 469             analysis: Some(analysis),
 470             resolutions: Some(resolutions),
 471             expanded_crate: Some(krate),
 472             hir_crate: Some(hir_crate),
 473             output_filenames: Some(output_filenames),
 474             out_file: out_file.as_ref().map(|s| &**s),
 475             ..CompileState::empty(input, session, out_dir)
 476         }
 477     }
 478
 479     fn state_after_analysis(input: &'a Input,
 480                             session: &'tcx Session,
 481                             out_dir: &'a Option<PathBuf>,
 482                             out_file: &'a Option<PathBuf>,
 483                             krate: Option<&'a ast::Crate>,
 484                             hir_crate: &'a hir::Crate,
 485                             analysis: &'a ty::CrateAnalysis,
 486                             tcx: TyCtxt<'a, 'tcx, 'tcx>,
 487                             crate_name: &'a str)
 488                             -> Self {
 489         CompileState {
 490             analysis: Some(analysis),
 491             tcx: Some(tcx),
 492             expanded_crate: krate,
 493             hir_crate: Some(hir_crate),
 494             crate_name: Some(crate_name),
 495             out_file: out_file.as_ref().map(|s| &**s),
 496             ..CompileState::empty(input, session, out_dir)
 497         }
 498     }
 499
 500     fn state_when_compilation_done(input: &'a Input,
 501                                    session: &'tcx Session,
 502                                    out_dir: &'a Option<PathBuf>,
 503                                    out_file: &'a Option<PathBuf>)
 504                                    -> Self {
 505         CompileState {
 506             out_file: out_file.as_ref().map(|s| &**s),
 507             ..CompileState::empty(input, session, out_dir)
 508         }
 509     }
 510 }
 511
 512 pub fn phase_1_parse_input<'a>(control: &CompileController,
 513                                sess: &'a Session,
 514                                input: &Input)
 515                                -> PResult<'a, ast::Crate> {
 516     sess.diagnostic().set_continue_after_error(control.continue_parse_after_error);
 517
 518     if sess.profile_queries() {
 519         profile::begin();
 520     }
 521
 522     let krate = time(sess.time_passes(), "parsing", || {
 523         match *input {
 524             Input::File(ref file) => {
 525                 parse::parse_crate_from_file(file, &sess.parse_sess)
 526             }
 527             Input::Str { ref input, ref name } => {
 528                 parse::parse_crate_from_source_str(name.clone(),
 529                                                    input.clone(),
 530                                                    &sess.parse_sess)
 531             }
 532         }
 533     })?;
 534
 535     sess.diagnostic().set_continue_after_error(true);
 536
 537     if sess.opts.debugging_opts.ast_json_noexpand {
 538         println!("{}", json::as_json(&krate));
 539     }
 540
 541     if sess.opts.debugging_opts.input_stats {
 542         println!("Lines of code:             {}", sess.codemap().count_lines());
 543         println!("Pre-expansion node count:  {}", count_nodes(&krate));
 544     }
 545
 546     if let Some(ref s) = sess.opts.debugging_opts.show_span {
 547         syntax::show_span::run(sess.diagnostic(), s, &krate);
 548     }
 549
 550     if sess.opts.debugging_opts.hir_stats {
 551         hir_stats::print_ast_stats(&krate, "PRE EXPANSION AST STATS");
 552     }
 553
 554     Ok(krate)
 555 }
 556
 557 fn count_nodes(krate: &ast::Crate) -> usize {
 558     let mut counter = NodeCounter::new();
 559     visit::walk_crate(&mut counter, krate);
 560     counter.count
 561 }
 562
 563 // For continuing compilation after a parsed crate has been
 564 // modified
 565
 566 pub struct ExpansionResult {
 567     pub expanded_crate: ast::Crate,
 568     pub defs: hir_map::Definitions,
 569     pub analysis: ty::CrateAnalysis,
 570     pub resolutions: Resolutions,
 571     pub hir_forest: hir_map::Forest,
 572 }
 573
 574 pub struct InnerExpansionResult<'a> {
 575     pub expanded_crate: ast::Crate,
 576     pub resolver: Resolver<'a>,
 577     pub hir_forest: hir_map::Forest,
 578 }
 579
 580 /// Run the "early phases" of the compiler: initial `cfg` processing,
 581 /// loading compiler plugins (including those from `addl_plugins`),
 582 /// syntax expansion, secondary `cfg` expansion, synthesis of a test
 583 /// harness if one is to be provided, injection of a dependency on the
 584 /// standard library and prelude, and name resolution.
 585 ///
 586 /// Returns `None` if we're aborting after handling -W help.
 587 pub fn phase_2_configure_and_expand<F>(sess: &Session,
 588                                        cstore: &CStore,
 589                                        krate: ast::Crate,
 590                                        registry: Option<Registry>,
 591                                        crate_name: &str,
 592                                        addl_plugins: Option<Vec<String>>,
 593                                        make_glob_map: MakeGlobMap,
 594                                        after_expand: F)
 595                                        -> Result<ExpansionResult, CompileIncomplete>
 596     where F: FnOnce(&ast::Crate) -> CompileResult {
 597     // Currently, we ignore the name resolution data structures for the purposes of dependency
 598     // tracking. Instead we will run name resolution and include its output in the hash of each
 599     // item, much like we do for macro expansion. In other words, the hash reflects not just
 600     // its contents but the results of name resolution on those contents. Hopefully we'll push
 601     // this back at some point.
 602     let mut crate_loader = CrateLoader::new(sess, &cstore, &crate_name);
 603     let resolver_arenas = Resolver::arenas();
 604     let result = phase_2_configure_and_expand_inner(sess, cstore, krate, registry, crate_name,
 605                                                     addl_plugins, make_glob_map, &resolver_arenas,
 606                                                     &mut crate_loader, after_expand);
 607     match result {
 608         Ok(InnerExpansionResult {expanded_crate, resolver, hir_forest}) => {
 609             Ok(ExpansionResult {
 610                 expanded_crate,
 611                 defs: resolver.definitions,
 612                 hir_forest,
 613                 resolutions: Resolutions {
 614                     freevars: resolver.freevars,
 615                     export_map: resolver.export_map,
 616                     trait_map: resolver.trait_map,
 617                     maybe_unused_trait_imports: resolver.maybe_unused_trait_imports,
 618                     maybe_unused_extern_crates: resolver.maybe_unused_extern_crates,
 619                 },
 620
 621                 analysis: ty::CrateAnalysis {
 622                     access_levels: Rc::new(AccessLevels::default()),
 623                     name: crate_name.to_string(),
 624                     glob_map: if resolver.make_glob_map { Some(resolver.glob_map) } else { None },
 625                 },
 626             })
 627         }
 628         Err(x) => Err(x)
 629     }
 630 }
 631
 632 /// Same as phase_2_configure_and_expand, but doesn't let you keep the resolver
 633 /// around
 634 pub fn phase_2_configure_and_expand_inner<'a, F>(sess: &'a Session,
 635                                        cstore: &'a CStore,
 636                                        krate: ast::Crate,
 637                                        registry: Option<Registry>,
 638                                        crate_name: &str,
 639                                        addl_plugins: Option<Vec<String>>,
 640                                        make_glob_map: MakeGlobMap,
 641                                        resolver_arenas: &'a ResolverArenas<'a>,
 642                                        crate_loader: &'a mut CrateLoader,
 643                                        after_expand: F)
 644                                        -> Result<InnerExpansionResult<'a>, CompileIncomplete>
 645     where F: FnOnce(&ast::Crate) -> CompileResult,
 646 {
 647     let time_passes = sess.time_passes();
 648
 649     let (mut krate, features) = syntax::config::features(krate, &sess.parse_sess, sess.opts.test);
 650     // these need to be set "early" so that expansion sees `quote` if enabled.
 651     *sess.features.borrow_mut() = features;
 652
 653     *sess.crate_types.borrow_mut() = collect_crate_types(sess, &krate.attrs);
 654
 655     let disambiguator = compute_crate_disambiguator(sess);
 656     *sess.crate_disambiguator.borrow_mut() = Some(disambiguator);
 657     rustc_incremental::prepare_session_directory(
 658         sess,
 659         &crate_name,
 660         disambiguator,
 661     );
 662
 663     if sess.opts.incremental.is_some() {
 664         time(time_passes, "garbage collect incremental cache directory", || {
 665             if let Err(e) = rustc_incremental::garbage_collect_session_directories(sess) {
 666                 warn!("Error while trying to garbage collect incremental \
 667                        compilation cache directory: {}", e);
 668             }
 669         });
 670     }
 671
 672     // If necessary, compute the dependency graph (in the background).
 673     let future_dep_graph = if sess.opts.build_dep_graph() {
 674         Some(rustc_incremental::load_dep_graph(sess, time_passes))
 675     } else {
 676         None
 677     };
 678
 679     time(time_passes, "recursion limit", || {
 680         middle::recursion_limit::update_limits(sess, &krate);
 681     });
 682
 683     krate = time(time_passes, "crate injection", || {
 684         let alt_std_name = sess.opts.alt_std_name.clone();
 685         syntax::std_inject::maybe_inject_crates_ref(krate, alt_std_name)
 686     });
 687
 688     let mut addl_plugins = Some(addl_plugins);
 689     let registrars = time(time_passes, "plugin loading", || {
 690         plugin::load::load_plugins(sess,
 691                                    &cstore,
 692                                    &krate,
 693                                    crate_name,
 694                                    addl_plugins.take().unwrap())
 695     });
 696
 697     let mut registry = registry.unwrap_or(Registry::new(sess, krate.span));
 698
 699     time(time_passes, "plugin registration", || {
 700         if sess.features.borrow().rustc_diagnostic_macros {
 701             registry.register_macro("__diagnostic_used",
 702                                     diagnostics::plugin::expand_diagnostic_used);
 703             registry.register_macro("__register_diagnostic",
 704                                     diagnostics::plugin::expand_register_diagnostic);
 705             registry.register_macro("__build_diagnostic_array",
 706                                     diagnostics::plugin::expand_build_diagnostic_array);
 707         }
 708
 709         for registrar in registrars {
 710             registry.args_hidden = Some(registrar.args);
 711             (registrar.fun)(&mut registry);
 712         }
 713     });
 714
 715     let whitelisted_legacy_custom_derives = registry.take_whitelisted_custom_derives();
 716     let Registry { syntax_exts, early_lint_passes, late_lint_passes, lint_groups,
 717                    llvm_passes, attributes, .. } = registry;
 718
 719     sess.track_errors(|| {
 720         let mut ls = sess.lint_store.borrow_mut();
 721         for pass in early_lint_passes {
 722             ls.register_early_pass(Some(sess), true, pass);
 723         }
 724         for pass in late_lint_passes {
 725             ls.register_late_pass(Some(sess), true, pass);
 726         }
 727
 728         for (name, to) in lint_groups {
 729             ls.register_group(Some(sess), true, name, to);
 730         }
 731
 732         *sess.plugin_llvm_passes.borrow_mut() = llvm_passes;
 733         *sess.plugin_attributes.borrow_mut() = attributes.clone();
 734     })?;
 735
 736     // Lint plugins are registered; now we can process command line flags.
 737     if sess.opts.describe_lints {
 738         super::describe_lints(&sess.lint_store.borrow(), true);
 739         return Err(CompileIncomplete::Stopped);
 740     }
 741
 742     let mut resolver = Resolver::new(sess,
 743                                      cstore,
 744                                      &krate,
 745                                      crate_name,
 746                                      make_glob_map,
 747                                      crate_loader,
 748                                      &resolver_arenas);
 749     resolver.whitelisted_legacy_custom_derives = whitelisted_legacy_custom_derives;
 750     syntax_ext::register_builtins(&mut resolver, syntax_exts, sess.features.borrow().quote);
 751
 752     krate = time(time_passes, "expansion", || {
 753         // Windows dlls do not have rpaths, so they don't know how to find their
 754         // dependencies. It's up to us to tell the system where to find all the
 755         // dependent dlls. Note that this uses cfg!(windows) as opposed to
 756         // targ_cfg because syntax extensions are always loaded for the host
 757         // compiler, not for the target.
 758         //
 759         // This is somewhat of an inherently racy operation, however, as
 760         // multiple threads calling this function could possibly continue
 761         // extending PATH far beyond what it should. To solve this for now we
 762         // just don't add any new elements to PATH which are already there
 763         // within PATH. This is basically a targeted fix at #17360 for rustdoc
 764         // which runs rustc in parallel but has been seen (#33844) to cause
 765         // problems with PATH becoming too long.
 766         let mut old_path = OsString::new();
 767         if cfg!(windows) {
 768             old_path = env::var_os("PATH").unwrap_or(old_path);
 769             let mut new_path = sess.host_filesearch(PathKind::All)
 770                                    .get_dylib_search_paths();
 771             for path in env::split_paths(&old_path) {
 772                 if !new_path.contains(&path) {
 773                     new_path.push(path);
 774                 }
 775             }
 776             env::set_var("PATH",
 777                 &env::join_paths(new_path.iter()
 778                                          .filter(|p| env::join_paths(iter::once(p)).is_ok()))
 779                      .unwrap());
 780         }
 781         let features = sess.features.borrow();
 782         let cfg = syntax::ext::expand::ExpansionConfig {
 783             features: Some(&features),
 784             recursion_limit: sess.recursion_limit.get(),
 785             trace_mac: sess.opts.debugging_opts.trace_macros,
 786             should_test: sess.opts.test,
 787             ..syntax::ext::expand::ExpansionConfig::default(crate_name.to_string())
 788         };
 789
 790         let mut ecx = ExtCtxt::new(&sess.parse_sess, cfg, &mut resolver);
 791         let err_count = ecx.parse_sess.span_diagnostic.err_count();
 792
 793         let krate = ecx.monotonic_expander().expand_crate(krate);
 794
 795         ecx.check_unused_macros();
 796
 797         let mut missing_fragment_specifiers: Vec<_> =
 798             ecx.parse_sess.missing_fragment_specifiers.borrow().iter().cloned().collect();
 799         missing_fragment_specifiers.sort();
 800         for span in missing_fragment_specifiers {
 801             let lint = lint::builtin::MISSING_FRAGMENT_SPECIFIER;
 802             let msg = "missing fragment specifier";
 803             sess.buffer_lint(lint, ast::CRATE_NODE_ID, span, msg);
 804         }
 805         if ecx.parse_sess.span_diagnostic.err_count() - ecx.resolve_err_count > err_count {
 806             ecx.parse_sess.span_diagnostic.abort_if_errors();
 807         }
 808         if cfg!(windows) {
 809             env::set_var("PATH", &old_path);
 810         }
 811         krate
 812     });
 813
 814     krate = time(time_passes, "maybe building test harness", || {
 815         syntax::test::modify_for_testing(&sess.parse_sess,
 816                                          &mut resolver,
 817                                          sess.opts.test,
 818                                          krate,
 819                                          sess.diagnostic())
 820     });
 821
 822     // If we're actually rustdoc then there's no need to actually compile
 823     // anything, so switch everything to just looping
 824     if sess.opts.actually_rustdoc {
 825         krate = ReplaceBodyWithLoop::new(sess).fold_crate(krate);
 826     }
 827
 828     // If we're in rustdoc we're always compiling as an rlib, but that'll trip a
 829     // bunch of checks in the `modify` function below. For now just skip this
 830     // step entirely if we're rustdoc as it's not too useful anyway.
 831     if !sess.opts.actually_rustdoc {
 832         krate = time(time_passes, "maybe creating a macro crate", || {
 833             let crate_types = sess.crate_types.borrow();
 834             let num_crate_types = crate_types.len();
 835             let is_proc_macro_crate = crate_types.contains(&config::CrateTypeProcMacro);
 836             let is_test_crate = sess.opts.test;
 837             syntax_ext::proc_macro_registrar::modify(&sess.parse_sess,
 838                                                      &mut resolver,
 839                                                      krate,
 840                                                      is_proc_macro_crate,
 841                                                      is_test_crate,
 842                                                      num_crate_types,
 843                                                      sess.diagnostic())
 844         });
 845     }
 846
 847     krate = time(time_passes, "creating allocators", || {
 848         allocator::expand::modify(&sess.parse_sess,
 849                                   &mut resolver,
 850                                   krate,
 851                                   sess.diagnostic())
 852     });
 853
 854     after_expand(&krate)?;
 855
 856     if sess.opts.debugging_opts.input_stats {
 857         println!("Post-expansion node count: {}", count_nodes(&krate));
 858     }
 859
 860     if sess.opts.debugging_opts.hir_stats {
 861         hir_stats::print_ast_stats(&krate, "POST EXPANSION AST STATS");
 862     }
 863
 864     if sess.opts.debugging_opts.ast_json {
 865         println!("{}", json::as_json(&krate));
 866     }
 867
 868     time(time_passes,
 869          "AST validation",
 870          || ast_validation::check_crate(sess, &krate));
 871
 872     time(time_passes, "name resolution", || -> CompileResult {
 873         resolver.resolve_crate(&krate);
 874         Ok(())
 875     })?;
 876
 877     if resolver.found_unresolved_macro {
 878         sess.parse_sess.span_diagnostic.abort_if_errors();
 879     }
 880
 881     // Needs to go *after* expansion to be able to check the results of macro expansion.
 882     time(time_passes, "complete gated feature checking", || {
 883         sess.track_errors(|| {
 884             syntax::feature_gate::check_crate(&krate,
 885                                               &sess.parse_sess,
 886                                               &sess.features.borrow(),
 887                                               &attributes,
 888                                               sess.opts.unstable_features);
 889         })
 890     })?;
 891
 892     // Lower ast -> hir.
 893     // First, we need to collect the dep_graph.
 894     let dep_graph = match future_dep_graph {
 895         None => DepGraph::new_disabled(),
 896         Some(future) => {
 897             let prev_graph = time(time_passes, "blocked while dep-graph loading finishes", || {
 898                 future.open()
 899                       .expect("Could not join with background dep_graph thread")
 900                       .open(sess)
 901             });
 902             DepGraph::new(prev_graph)
 903         }
 904     };
 905     let hir_forest = time(time_passes, "lowering ast -> hir", || {
 906         let hir_crate = lower_crate(sess, cstore, &dep_graph, &krate, &mut resolver);
 907
 908         if sess.opts.debugging_opts.hir_stats {
 909             hir_stats::print_hir_stats(&hir_crate);
 910         }
 911
 912         hir_map::Forest::new(hir_crate, &dep_graph)
 913     });
 914
 915     time(time_passes,
 916          "early lint checks",
 917          || lint::check_ast_crate(sess, &krate));
 918
 919     // Discard hygiene data, which isn't required after lowering to HIR.
 920     if !sess.opts.debugging_opts.keep_hygiene_data {
 921         syntax::ext::hygiene::clear_markings();
 922     }
 923
 924     Ok(InnerExpansionResult {
 925         expanded_crate: krate,
 926         resolver,
 927         hir_forest,
 928     })
 929 }
 930
 931 pub fn default_provide(providers: &mut ty::maps::Providers) {
 932     borrowck::provide(providers);
 933     mir::provide(providers);
 934     reachable::provide(providers);
 935     resolve_lifetime::provide(providers);
 936     rustc_privacy::provide(providers);
 937     typeck::provide(providers);
 938     ty::provide(providers);
 939     traits::provide(providers);
 940     reachable::provide(providers);
 941     rustc_const_eval::provide(providers);
 942     rustc_passes::provide(providers);
 943     middle::region::provide(providers);
 944     cstore::provide(providers);
 945     lint::provide(providers);
 946 }
 947
 948 pub fn default_provide_extern(providers: &mut ty::maps::Providers) {
 949     cstore::provide_extern(providers);
 950 }
 951
 952 /// Run the resolution, typechecking, region checking and other
 953 /// miscellaneous analysis passes on the crate. Return various
 954 /// structures carrying the results of the analysis.
 955 pub fn phase_3_run_analysis_passes<'tcx, F, R>(trans: &TransCrate,
 956                                                control: &CompileController,
 957                                                sess: &'tcx Session,
 958                                                cstore: &'tcx CrateStore,
 959                                                hir_map: hir_map::Map<'tcx>,
 960                                                mut analysis: ty::CrateAnalysis,
 961                                                resolutions: Resolutions,
 962                                                arenas: &'tcx AllArenas<'tcx>,
 963                                                name: &str,
 964                                                output_filenames: &OutputFilenames,
 965                                                f: F)
 966                                                -> Result<R, CompileIncomplete>
 967     where F: for<'a> FnOnce(TyCtxt<'a, 'tcx, 'tcx>,
 968                             ty::CrateAnalysis,
 969                             mpsc::Receiver<Box<Any + Send>>,
 970                             CompileResult) -> R
 971 {
 972     let time_passes = sess.time_passes();
 973
 974     let query_result_on_disk_cache = time(time_passes,
 975         "load query result cache",
 976         || rustc_incremental::load_query_result_cache(sess));
 977
 978     time(time_passes,
 979          "looking for entry point",
 980          || middle::entry::find_entry_point(sess, &hir_map));
 981
 982     sess.plugin_registrar_fn.set(time(time_passes, "looking for plugin registrar", || {
 983         plugin::build::find_plugin_registrar(sess.diagnostic(), &hir_map)
 984     }));
 985     sess.derive_registrar_fn.set(derive_registrar::find(&hir_map));
 986
 987     time(time_passes,
 988          "loop checking",
 989          || loops::check_crate(sess, &hir_map));
 990
 991     time(time_passes,
 992               "static item recursion checking",
 993               || static_recursion::check_crate(sess, &hir_map))?;
 994
 995     let mut local_providers = ty::maps::Providers::default();
 996     default_provide(&mut local_providers);
 997     trans.provide(&mut local_providers);
 998     (control.provide)(&mut local_providers);
 999
1000     let mut extern_providers = local_providers;
1001     default_provide_extern(&mut extern_providers);
1002     trans.provide_extern(&mut extern_providers);
1003     (control.provide_extern)(&mut extern_providers);
1004
1005     let (tx, rx) = mpsc::channel();
1006
1007     TyCtxt::create_and_enter(sess,
1008                              cstore,
1009                              local_providers,
1010                              extern_providers,
1011                              arenas,
1012                              resolutions,
1013                              hir_map,
1014                              query_result_on_disk_cache,
1015                              name,
1016                              tx,
1017                              output_filenames,
1018                              |tcx| {
1019         // Do some initialization of the DepGraph that can only be done with the
1020         // tcx available.
1021         rustc_incremental::dep_graph_tcx_init(tcx);
1022
1023         time(sess.time_passes(), "attribute checking", || {
1024             hir::check_attr::check_crate(tcx)
1025         });
1026
1027         time(time_passes,
1028              "stability checking",
1029              || stability::check_unstable_api_usage(tcx));
1030
1031         // passes are timed inside typeck
1032         match typeck::check_crate(tcx) {
1033             Ok(x) => x,
1034             Err(x) => {
1035                 f(tcx, analysis, rx, Err(x));
1036                 return Err(x);
1037             }
1038         }
1039
1040         time(time_passes,
1041              "const checking",
1042              || consts::check_crate(tcx));
1043
1044         analysis.access_levels =
1045             time(time_passes, "privacy checking", || rustc_privacy::check_crate(tcx));
1046
1047         time(time_passes,
1048              "intrinsic checking",
1049              || middle::intrinsicck::check_crate(tcx));
1050
1051         time(time_passes,
1052              "match checking",
1053              || check_match::check_crate(tcx));
1054
1055         // this must run before MIR dump, because
1056         // "not all control paths return a value" is reported here.
1057         //
1058         // maybe move the check to a MIR pass?
1059         time(time_passes,
1060              "liveness checking",
1061              || middle::liveness::check_crate(tcx));
1062
1063         time(time_passes,
1064              "borrow checking",
1065              || borrowck::check_crate(tcx));
1066
1067         time(time_passes,
1068              "MIR borrow checking",
1069              || for def_id in tcx.body_owners() { tcx.mir_borrowck(def_id); });
1070
1071         time(time_passes,
1072              "MIR effect checking",
1073              || for def_id in tcx.body_owners() {
1074                  mir::transform::check_unsafety::check_unsafety(tcx, def_id)
1075              });
1076         // Avoid overwhelming user with errors if type checking failed.
1077         // I'm not sure how helpful this is, to be honest, but it avoids
1078         // a
1079         // lot of annoying errors in the compile-fail tests (basically,
1080         // lint warnings and so on -- kindck used to do this abort, but
1081         // kindck is gone now). -nmatsakis
1082         if sess.err_count() > 0 {
1083             return Ok(f(tcx, analysis, rx, sess.compile_status()));
1084         }
1085
1086         time(time_passes, "death checking", || middle::dead::check_crate(tcx));
1087
1088         time(time_passes, "unused lib feature checking", || {
1089             stability::check_unused_or_stable_features(tcx)
1090         });
1091
1092         time(time_passes, "lint checking", || lint::check_crate(tcx));
1093
1094         return Ok(f(tcx, analysis, rx, tcx.sess.compile_status()));
1095     })
1096 }
1097
1098 /// Run the translation phase to LLVM, after which the AST and analysis can
1099 /// be discarded.
1100 pub fn phase_4_translate_to_llvm<'a, 'tcx>(trans: &TransCrate,
1101                                            tcx: TyCtxt<'a, 'tcx, 'tcx>,
1102                                            rx: mpsc::Receiver<Box<Any + Send>>)
1103                                            -> Box<Any> {
1104     let time_passes = tcx.sess.time_passes();
1105
1106     time(time_passes,
1107          "resolving dependency formats",
1108          || ::rustc::middle::dependency_format::calculate(tcx));
1109
1110     let translation =
1111         time(time_passes, "translation", move || {
1112             trans.trans_crate(tcx, rx)
1113         });
1114     if tcx.sess.profile_queries() {
1115         profile::dump("profile_queries".to_string())
1116     }
1117
1118     translation
1119 }
1120
1121 fn escape_dep_filename(filename: &FileName) -> String {
1122     // Apparently clang and gcc *only* escape spaces:
1123     // http://llvm.org/klaus/clang/commit/9d50634cfc268ecc9a7250226dd5ca0e945240d4
1124     filename.to_string().replace(" ", "\\ ")
1125 }
1126
1127 // Returns all the paths that correspond to generated files.
1128 fn generated_output_paths(sess: &Session,
1129                           outputs: &OutputFilenames,
1130                           exact_name: bool,
1131                           crate_name: &str) -> Vec<PathBuf> {
1132     let mut out_filenames = Vec::new();
1133     for output_type in sess.opts.output_types.keys() {
1134         let file = outputs.path(*output_type);
1135         match *output_type {
1136             // If the filename has been overridden using `-o`, it will not be modified
1137             // by appending `.rlib`, `.exe`, etc., so we can skip this transformation.
1138             OutputType::Exe if !exact_name => {
1139                 for crate_type in sess.crate_types.borrow().iter() {
1140                     let p = ::rustc_trans_utils::link::filename_for_input(
1141                         sess,
1142                         *crate_type,
1143                         crate_name,
1144                         outputs
1145                     );
1146                     out_filenames.push(p);
1147                 }
1148             }
1149             OutputType::DepInfo if sess.opts.debugging_opts.dep_info_omit_d_target => {
1150                 // Don't add the dep-info output when omitting it from dep-info targets
1151             }
1152             _ => {
1153                 out_filenames.push(file);
1154             }
1155         }
1156     }
1157     out_filenames
1158 }
1159
1160 // Runs `f` on every output file path and returns the first non-None result, or None if `f`
1161 // returns None for every file path.
1162 fn check_output<F, T>(output_paths: &Vec<PathBuf>, f: F) -> Option<T>
1163         where F: Fn(&PathBuf) -> Option<T> {
1164             for output_path in output_paths {
1165                 if let Some(result) = f(output_path) {
1166                     return Some(result);
1167                 }
1168             }
1169             None
1170 }
1171
1172 pub fn output_contains_path(output_paths: &Vec<PathBuf>, input_path: &PathBuf) -> bool {
1173     let input_path = input_path.canonicalize().ok();
1174     if input_path.is_none() {
1175         return false
1176     }
1177     let check = |output_path: &PathBuf| {
1178         if output_path.canonicalize().ok() == input_path {
1179             Some(())
1180         } else { None }
1181     };
1182     check_output(output_paths, check).is_some()
1183 }
1184
1185 pub fn output_conflicts_with_dir(output_paths: &Vec<PathBuf>) -> Option<PathBuf> {
1186     let check = |output_path: &PathBuf| {
1187         if output_path.is_dir() {
1188             Some(output_path.clone())
1189         } else { None }
1190     };
1191     check_output(output_paths, check)
1192 }
1193
1194 fn write_out_deps(sess: &Session,
1195                   outputs: &OutputFilenames,
1196                   out_filenames: &Vec<PathBuf>) {
1197     // Write out dependency rules to the dep-info file if requested
1198     if !sess.opts.output_types.contains_key(&OutputType::DepInfo) {
1199         return;
1200     }
1201     let deps_filename = outputs.path(OutputType::DepInfo);
1202
1203     let result =
1204         (|| -> io::Result<()> {
1205             // Build a list of files used to compile the output and
1206             // write Makefile-compatible dependency rules
1207             let files: Vec<String> = sess.codemap()
1208                                          .files()
1209                                          .iter()
1210                                          .filter(|fmap| fmap.is_real_file())
1211                                          .filter(|fmap| !fmap.is_imported())
1212                                          .map(|fmap| escape_dep_filename(&fmap.name))
1213                                          .collect();
1214             let mut file = fs::File::create(&deps_filename)?;
1215             for path in out_filenames {
1216                 write!(file, "{}: {}\n\n", path.display(), files.join(" "))?;
1217             }
1218
1219             // Emit a fake target for each input file to the compilation. This
1220             // prevents `make` from spitting out an error if a file is later
1221             // deleted. For more info see #28735
1222             for path in files {
1223                 writeln!(file, "{}:", path)?;
1224             }
1225             Ok(())
1226         })();
1227
1228     match result {
1229         Ok(()) => {}
1230         Err(e) => {
1231             sess.fatal(&format!("error writing dependencies to `{}`: {}",
1232                                 deps_filename.display(),
1233                                 e));
1234         }
1235     }
1236 }
1237
1238 pub fn collect_crate_types(session: &Session, attrs: &[ast::Attribute]) -> Vec<config::CrateType> {
1239     // Unconditionally collect crate types from attributes to make them used
1240     let attr_types: Vec<config::CrateType> =
1241         attrs.iter()
1242              .filter_map(|a| {
1243                  if a.check_name("crate_type") {
1244                      match a.value_str() {
1245                          Some(ref n) if *n == "rlib" => {
1246                              Some(config::CrateTypeRlib)
1247                          }
1248                          Some(ref n) if *n == "dylib" => {
1249                              Some(config::CrateTypeDylib)
1250                          }
1251                          Some(ref n) if *n == "cdylib" => {
1252                              Some(config::CrateTypeCdylib)
1253                          }
1254                          Some(ref n) if *n == "lib" => {
1255                              Some(config::default_lib_output())
1256                          }
1257                          Some(ref n) if *n == "staticlib" => {
1258                              Some(config::CrateTypeStaticlib)
1259                          }
1260                          Some(ref n) if *n == "proc-macro" => {
1261                              Some(config::CrateTypeProcMacro)
1262                          }
1263                          Some(ref n) if *n == "bin" => Some(config::CrateTypeExecutable),
1264                          Some(_) => {
1265                              session.buffer_lint(lint::builtin::UNKNOWN_CRATE_TYPES,
1266                                                  ast::CRATE_NODE_ID,
1267                                                  a.span,
1268                                                  "invalid `crate_type` value");
1269                              None
1270                          }
1271                          _ => {
1272                              session.struct_span_err(a.span, "`crate_type` requires a value")
1273                                  .note("for example: `#![crate_type=\"lib\"]`")
1274                                  .emit();
1275                              None
1276                          }
1277                      }
1278                  } else {
1279                      None
1280                  }
1281              })
1282              .collect();
1283
1284     // If we're generating a test executable, then ignore all other output
1285     // styles at all other locations
1286     if session.opts.test {
1287         return vec![config::CrateTypeExecutable];
1288     }
1289
1290     // Only check command line flags if present. If no types are specified by
1291     // command line, then reuse the empty `base` Vec to hold the types that
1292     // will be found in crate attributes.
1293     let mut base = session.opts.crate_types.clone();
1294     if base.is_empty() {
1295         base.extend(attr_types);
1296         if base.is_empty() {
1297             base.push(::rustc_trans_utils::link::default_output_for_target(session));
1298         }
1299         base.sort();
1300         base.dedup();
1301     }
1302
1303     base.into_iter()
1304         .filter(|crate_type| {
1305             let res = !::rustc_trans_utils::link::invalid_output_for_target(session, *crate_type);
1306
1307             if !res {
1308                 session.warn(&format!("dropping unsupported crate type `{}` for target `{}`",
1309                                       *crate_type,
1310                                       session.opts.target_triple));
1311             }
1312
1313             res
1314         })
1315         .collect()
1316 }
1317
1318 pub fn compute_crate_disambiguator(session: &Session) -> CrateDisambiguator {
1319     use std::hash::Hasher;
1320
1321     // The crate_disambiguator is a 128 bit hash. The disambiguator is fed
1322     // into various other hashes quite a bit (symbol hashes, incr. comp. hashes,
1323     // debuginfo type IDs, etc), so we don't want it to be too wide. 128 bits
1324     // should still be safe enough to avoid collisions in practice.
1325     let mut hasher = StableHasher::<Fingerprint>::new();
1326
1327     let mut metadata = session.opts.cg.metadata.clone();
1328     // We don't want the crate_disambiguator to dependent on the order
1329     // -C metadata arguments, so sort them:
1330     metadata.sort();
1331     // Every distinct -C metadata value is only incorporated once:
1332     metadata.dedup();
1333
1334     hasher.write(b"metadata");
1335     for s in &metadata {
1336         // Also incorporate the length of a metadata string, so that we generate
1337         // different values for `-Cmetadata=ab -Cmetadata=c` and
1338         // `-Cmetadata=a -Cmetadata=bc`
1339         hasher.write_usize(s.len());
1340         hasher.write(s.as_bytes());
1341     }
1342
1343     // Also incorporate crate type, so that we don't get symbol conflicts when
1344     // linking against a library of the same name, if this is an executable.
1345     let is_exe = session.crate_types.borrow().contains(&config::CrateTypeExecutable);
1346     hasher.write(if is_exe { b"exe" } else { b"lib" });
1347
1348     CrateDisambiguator::from(hasher.finish())
1349
1350 }
1351
1352 pub fn build_output_filenames(input: &Input,
1353                               odir: &Option<PathBuf>,
1354                               ofile: &Option<PathBuf>,
1355                               attrs: &[ast::Attribute],
1356                               sess: &Session)
1357                               -> OutputFilenames {
1358     match *ofile {
1359         None => {
1360             // "-" as input file will cause the parser to read from stdin so we
1361             // have to make up a name
1362             // We want to toss everything after the final '.'
1363             let dirpath = match *odir {
1364                 Some(ref d) => d.clone(),
1365                 None => PathBuf::new(),
1366             };
1367
1368             // If a crate name is present, we use it as the link name
1369             let stem = sess.opts
1370                            .crate_name
1371                            .clone()
1372                            .or_else(|| attr::find_crate_name(attrs).map(|n| n.to_string()))
1373                            .unwrap_or(input.filestem());
1374
1375             OutputFilenames {
1376                 out_directory: dirpath,
1377                 out_filestem: stem,
1378                 single_output_file: None,
1379                 extra: sess.opts.cg.extra_filename.clone(),
1380                 outputs: sess.opts.output_types.clone(),
1381             }
1382         }
1383
1384         Some(ref out_file) => {
1385             let unnamed_output_types = sess.opts
1386                                            .output_types
1387                                            .values()
1388                                            .filter(|a| a.is_none())
1389                                            .count();
1390             let ofile = if unnamed_output_types > 1 {
1391                 sess.warn("due to multiple output types requested, the explicitly specified \
1392                            output file name will be adapted for each output type");
1393                 None
1394             } else {
1395                 Some(out_file.clone())
1396             };
1397             if *odir != None {
1398                 sess.warn("ignoring --out-dir flag due to -o flag");
1399             }
1400             if !sess.opts.cg.extra_filename.is_empty() {
1401                 sess.warn("ignoring -C extra-filename flag due to -o flag");
1402             }
1403
1404             let cur_dir = Path::new("");
1405
1406             OutputFilenames {
1407                 out_directory: out_file.parent().unwrap_or(cur_dir).to_path_buf(),
1408                 out_filestem: out_file.file_stem()
1409                                       .unwrap_or(OsStr::new(""))
1410                                       .to_str()
1411                                       .unwrap()
1412                                       .to_string(),
1413                 single_output_file: ofile,
1414                 extra: sess.opts.cg.extra_filename.clone(),
1415                 outputs: sess.opts.output_types.clone(),
1416             }
1417         }
1418     }
1419 }