1 //! Validates all used crates and extern libraries and loads their metadata
3 use crate::locator::{CrateLocator, CratePaths};
4 use crate::rmeta::{CrateDep, CrateMetadata, CrateNumMap, CrateRoot, MetadataBlob};
6 use rustc::hir::map::Definitions;
7 use rustc::middle::cstore::DepKind;
8 use rustc::middle::cstore::{CrateSource, ExternCrate, ExternCrateSource, MetadataLoaderDyn};
9 use rustc::session::config;
10 use rustc::session::search_paths::PathKind;
11 use rustc::session::{CrateDisambiguator, Session};
12 use rustc::ty::TyCtxt;
13 use rustc_data_structures::svh::Svh;
14 use rustc_data_structures::sync::Lrc;
15 use rustc_error_codes::*;
16 use rustc_errors::struct_span_err;
17 use rustc_expand::base::SyntaxExtension;
18 use rustc_hir::def_id::{CrateNum, LOCAL_CRATE};
19 use rustc_index::vec::IndexVec;
20 use rustc_span::edition::Edition;
21 use rustc_span::symbol::{sym, Symbol};
22 use rustc_span::{Span, DUMMY_SP};
23 use rustc_target::spec::{PanicStrategy, TargetTriple};
26 use syntax::expand::allocator::{global_allocator_spans, AllocatorKind};
28 use log::{debug, info, log_enabled};
29 use proc_macro::bridge::client::ProcMacro;
35 metas: IndexVec<CrateNum, Option<Lrc<CrateMetadata>>>,
36 injected_panic_runtime: Option<CrateNum>,
37 /// This crate needs an allocator and either provides it itself, or finds it in a dependency.
38 /// If the above is true, then this field denotes the kind of the found allocator.
39 allocator_kind: Option<AllocatorKind>,
40 /// This crate has a `#[global_allocator]` item.
41 has_global_allocator: bool,
44 pub struct CrateLoader<'a> {
45 // Immutable configuration.
47 metadata_loader: &'a MetadataLoaderDyn,
48 local_crate_name: Symbol,
53 pub enum LoadedMacro {
54 MacroDef(ast::Item, Edition),
55 ProcMacro(SyntaxExtension),
58 crate struct Library {
59 pub source: CrateSource,
60 pub metadata: MetadataBlob,
69 LocatorError(CrateLocator<'a>),
72 impl<'a> LoadError<'a> {
73 fn report(self) -> ! {
75 LoadError::LocatorError(locator) => locator.report_errs(),
80 fn dump_crates(cstore: &CStore) {
81 info!("resolved crates:");
82 cstore.iter_crate_data(|cnum, data| {
83 info!(" name: {}", data.name());
84 info!(" cnum: {}", cnum);
85 info!(" hash: {}", data.hash());
86 info!(" reqd: {:?}", data.dep_kind());
87 let CrateSource { dylib, rlib, rmeta } = data.source();
88 dylib.as_ref().map(|dl| info!(" dylib: {}", dl.0.display()));
89 rlib.as_ref().map(|rl| info!(" rlib: {}", rl.0.display()));
90 rmeta.as_ref().map(|rl| info!(" rmeta: {}", rl.0.display()));
95 crate fn from_tcx(tcx: TyCtxt<'_>) -> &CStore {
96 tcx.cstore_as_any().downcast_ref::<CStore>().expect("`tcx.cstore` is not a `CStore`")
99 fn alloc_new_crate_num(&mut self) -> CrateNum {
100 self.metas.push(None);
101 CrateNum::new(self.metas.len() - 1)
104 crate fn get_crate_data(&self, cnum: CrateNum) -> &CrateMetadata {
107 .unwrap_or_else(|| panic!("Failed to get crate data for {:?}", cnum))
110 fn set_crate_data(&mut self, cnum: CrateNum, data: CrateMetadata) {
111 assert!(self.metas[cnum].is_none(), "Overwriting crate metadata entry");
112 self.metas[cnum] = Some(Lrc::new(data));
115 crate fn iter_crate_data(&self, mut f: impl FnMut(CrateNum, &CrateMetadata)) {
116 for (cnum, data) in self.metas.iter_enumerated() {
117 if let Some(data) = data {
123 fn push_dependencies_in_postorder(&self, deps: &mut Vec<CrateNum>, cnum: CrateNum) {
124 if !deps.contains(&cnum) {
125 let data = self.get_crate_data(cnum);
126 for &dep in data.dependencies().iter() {
128 self.push_dependencies_in_postorder(deps, dep);
136 crate fn crate_dependencies_in_postorder(&self, cnum: CrateNum) -> Vec<CrateNum> {
137 let mut deps = Vec::new();
138 if cnum == LOCAL_CRATE {
139 self.iter_crate_data(|cnum, _| self.push_dependencies_in_postorder(&mut deps, cnum));
141 self.push_dependencies_in_postorder(&mut deps, cnum);
146 fn crate_dependencies_in_reverse_postorder(&self, cnum: CrateNum) -> Vec<CrateNum> {
147 let mut deps = self.crate_dependencies_in_postorder(cnum);
152 crate fn injected_panic_runtime(&self) -> Option<CrateNum> {
153 self.injected_panic_runtime
156 crate fn allocator_kind(&self) -> Option<AllocatorKind> {
160 crate fn has_global_allocator(&self) -> bool {
161 self.has_global_allocator
165 impl<'a> CrateLoader<'a> {
168 metadata_loader: &'a MetadataLoaderDyn,
169 local_crate_name: &str,
174 local_crate_name: Symbol::intern(local_crate_name),
176 // We add an empty entry for LOCAL_CRATE (which maps to zero) in
177 // order to make array indices in `metas` match with the
178 // corresponding `CrateNum`. This first entry will always remain
180 metas: IndexVec::from_elem_n(None, 1),
181 injected_panic_runtime: None,
182 allocator_kind: None,
183 has_global_allocator: false,
188 pub fn cstore(&self) -> &CStore {
192 pub fn into_cstore(self) -> CStore {
196 fn existing_match(&self, name: Symbol, hash: Option<Svh>, kind: PathKind) -> Option<CrateNum> {
198 self.cstore.iter_crate_data(|cnum, data| {
199 if data.name() != name {
204 Some(hash) if hash == data.hash() => {
212 // When the hash is None we're dealing with a top-level dependency
213 // in which case we may have a specification on the command line for
214 // this library. Even though an upstream library may have loaded
215 // something of the same name, we have to make sure it was loaded
216 // from the exact same location as well.
218 // We're also sure to compare *paths*, not actual byte slices. The
219 // `source` stores paths which are normalized which may be different
220 // from the strings on the command line.
221 let source = self.cstore.get_crate_data(cnum).source();
222 if let Some(entry) = self.sess.opts.externs.get(&name.as_str()) {
223 // Only use `--extern crate_name=path` here, not `--extern crate_name`.
224 if let Some(mut files) = entry.files() {
226 let l = fs::canonicalize(l).ok();
227 source.dylib.as_ref().map(|p| &p.0) == l.as_ref()
228 || source.rlib.as_ref().map(|p| &p.0) == l.as_ref()
236 // Alright, so we've gotten this far which means that `data` has the
237 // right name, we don't have a hash, and we don't have a --extern
238 // pointing for ourselves. We're still not quite yet done because we
239 // have to make sure that this crate was found in the crate lookup
240 // path (this is a top-level dependency) as we don't want to
241 // implicitly load anything inside the dependency lookup path.
242 let prev_kind = source
245 .or(source.rlib.as_ref())
246 .or(source.rmeta.as_ref())
247 .expect("No sources for crate")
249 if kind.matches(prev_kind) {
256 fn verify_no_symbol_conflicts(&self, span: Span, root: &CrateRoot<'_>) {
257 // Check for (potential) conflicts with the local crate
258 if self.local_crate_name == root.name()
259 && self.sess.local_crate_disambiguator() == root.disambiguator()
265 "the current crate is indistinguishable from one of its \
266 dependencies: it has the same crate-name `{}` and was \
267 compiled with the same `-C metadata` arguments. This \
268 will result in symbol conflicts between the two.",
274 // Check for conflicts with any crate loaded so far
275 self.cstore.iter_crate_data(|_, other| {
276 if other.name() == root.name() && // same crate-name
277 other.disambiguator() == root.disambiguator() && // same crate-disambiguator
278 other.hash() != root.hash()
285 "found two different crates with name `{}` that are \
286 not distinguished by differing `-C metadata`. This \
287 will result in symbol conflicts between the two.",
297 host_lib: Option<Library>,
298 root: Option<&CratePaths>,
304 let _prof_timer = self.sess.prof.generic_activity("metadata_register_crate");
306 let Library { source, metadata } = lib;
307 let crate_root = metadata.get_root();
308 let host_hash = host_lib.as_ref().map(|lib| lib.metadata.get_root().hash());
309 self.verify_no_symbol_conflicts(span, &crate_root);
312 self.sess.opts.externs.get(&name.as_str()).map(|e| e.is_private_dep).unwrap_or(false);
314 info!("register crate `{}` (private_dep = {})", crate_root.name(), private_dep);
316 // Claim this crate number and cache it
317 let cnum = self.cstore.alloc_new_crate_num();
319 // Maintain a reference to the top most crate.
320 // Stash paths for top-most crate locally if necessary.
322 let root = if let Some(root) = root {
325 crate_paths = CratePaths::new(crate_root.name(), source.clone());
329 let cnum_map = self.resolve_crate_deps(root, &crate_root, &metadata, cnum, span, dep_kind);
331 let raw_proc_macros = if crate_root.is_proc_macro_crate() {
333 let (dlsym_source, dlsym_root) = match &host_lib {
334 Some(host_lib) => (&host_lib.source, {
335 temp_root = host_lib.metadata.get_root();
338 None => (&source, &crate_root),
340 let dlsym_dylib = dlsym_source.dylib.as_ref().expect("no dylib for a proc-macro crate");
341 Some(self.dlsym_proc_macros(&dlsym_dylib.0, dlsym_root.disambiguator(), span))
346 self.cstore.set_crate_data(
365 fn load_proc_macro<'b>(
367 locator: &mut CrateLocator<'b>,
369 ) -> Option<(LoadResult, Option<Library>)>
373 // Use a new crate locator so trying to load a proc macro doesn't affect the error
375 let mut proc_macro_locator = locator.clone();
377 // Try to load a proc macro
378 proc_macro_locator.is_proc_macro = Some(true);
380 // Load the proc macro crate for the target
381 let (locator, target_result) = if self.sess.opts.debugging_opts.dual_proc_macros {
382 proc_macro_locator.reset();
383 let result = match self.load(&mut proc_macro_locator)? {
384 LoadResult::Previous(cnum) => return Some((LoadResult::Previous(cnum), None)),
385 LoadResult::Loaded(library) => Some(LoadResult::Loaded(library)),
387 locator.hash = locator.host_hash;
388 // Use the locator when looking for the host proc macro crate, as that is required
389 // so we want it to affect the error message
392 (&mut proc_macro_locator, None)
395 // Load the proc macro crate for the host
398 locator.is_proc_macro = Some(true);
399 locator.target = &self.sess.host;
400 locator.triple = TargetTriple::from_triple(config::host_triple());
401 locator.filesearch = self.sess.host_filesearch(path_kind);
403 let host_result = self.load(locator)?;
405 Some(if self.sess.opts.debugging_opts.dual_proc_macros {
406 let host_result = match host_result {
407 LoadResult::Previous(..) => {
408 panic!("host and target proc macros must be loaded in lock-step")
410 LoadResult::Loaded(library) => library,
412 (target_result.unwrap(), Some(host_result))
418 fn resolve_crate<'b>(
423 dep: Option<(&'b CratePaths, &'b CrateDep)>,
425 self.maybe_resolve_crate(name, span, dep_kind, dep).unwrap_or_else(|err| err.report())
428 fn maybe_resolve_crate<'b>(
432 mut dep_kind: DepKind,
433 dep: Option<(&'b CratePaths, &'b CrateDep)>,
434 ) -> Result<CrateNum, LoadError<'b>> {
435 info!("resolving crate `{}`", name);
436 let (root, hash, host_hash, extra_filename, path_kind) = match dep {
437 Some((root, dep)) => (
441 Some(&dep.extra_filename[..]),
442 PathKind::Dependency,
444 None => (None, None, None, None, PathKind::Crate),
446 let result = if let Some(cnum) = self.existing_match(name, hash, path_kind) {
447 (LoadResult::Previous(cnum), None)
449 info!("falling back to a load");
450 let mut locator = CrateLocator::new(
452 self.metadata_loader,
461 Some(false), // is_proc_macro
464 self.load(&mut locator)
467 dep_kind = DepKind::UnexportedMacrosOnly;
468 self.load_proc_macro(&mut locator, path_kind)
470 .ok_or_else(move || LoadError::LocatorError(locator))?
474 (LoadResult::Previous(cnum), None) => {
475 let data = self.cstore.get_crate_data(cnum);
476 if data.is_proc_macro_crate() {
477 dep_kind = DepKind::UnexportedMacrosOnly;
479 data.update_dep_kind(|data_dep_kind| cmp::max(data_dep_kind, dep_kind));
482 (LoadResult::Loaded(library), host_library) => {
483 Ok(self.register_crate(host_library, root, span, library, dep_kind, name))
489 fn load(&self, locator: &mut CrateLocator<'_>) -> Option<LoadResult> {
490 let library = locator.maybe_load_library_crate()?;
492 // In the case that we're loading a crate, but not matching
493 // against a hash, we could load a crate which has the same hash
494 // as an already loaded crate. If this is the case prevent
495 // duplicates by just using the first crate.
497 // Note that we only do this for target triple crates, though, as we
498 // don't want to match a host crate against an equivalent target one
500 let root = library.metadata.get_root();
501 if locator.triple == self.sess.opts.target_triple {
502 let mut result = LoadResult::Loaded(library);
503 self.cstore.iter_crate_data(|cnum, data| {
504 if data.name() == root.name() && root.hash() == data.hash() {
505 assert!(locator.hash.is_none());
506 info!("load success, going to previous cnum: {}", cnum);
507 result = LoadResult::Previous(cnum);
512 Some(LoadResult::Loaded(library))
516 fn update_extern_crate(&self, cnum: CrateNum, extern_crate: ExternCrate) {
517 let cmeta = self.cstore.get_crate_data(cnum);
518 if cmeta.update_extern_crate(extern_crate) {
519 // Propagate the extern crate info to dependencies if it was updated.
520 let extern_crate = ExternCrate { dependency_of: cnum, ..extern_crate };
521 for &dep_cnum in cmeta.dependencies().iter() {
522 self.update_extern_crate(dep_cnum, extern_crate);
527 // Go through the crate metadata and load any crates that it references
528 fn resolve_crate_deps(
531 crate_root: &CrateRoot<'_>,
532 metadata: &MetadataBlob,
537 debug!("resolving deps of external crate");
538 if crate_root.is_proc_macro_crate() {
539 return CrateNumMap::new();
542 // The map from crate numbers in the crate we're resolving to local crate numbers.
543 // We map 0 and all other holes in the map to our parent crate. The "additional"
544 // self-dependencies should be harmless.
545 std::iter::once(krate)
546 .chain(crate_root.decode_crate_deps(metadata).map(|dep| {
548 "resolving dep crate {} hash: `{}` extra filename: `{}`",
549 dep.name, dep.hash, dep.extra_filename
551 if dep.kind == DepKind::UnexportedMacrosOnly {
554 let dep_kind = match dep_kind {
555 DepKind::MacrosOnly => DepKind::MacrosOnly,
558 self.resolve_crate(dep.name, span, dep_kind, Some((root, &dep)))
563 fn dlsym_proc_macros(
566 disambiguator: CrateDisambiguator,
568 ) -> &'static [ProcMacro] {
569 use crate::dynamic_lib::DynamicLibrary;
572 // Make sure the path contains a / or the linker will search for it.
573 let path = env::current_dir().unwrap().join(path);
574 let lib = match DynamicLibrary::open(Some(&path)) {
576 Err(err) => self.sess.span_fatal(span, &err),
579 let sym = self.sess.generate_proc_macro_decls_symbol(disambiguator);
581 let sym = match lib.symbol(&sym) {
583 Err(err) => self.sess.span_fatal(span, &err),
585 *(sym as *const &[ProcMacro])
588 // Intentionally leak the dynamic library. We can't ever unload it
589 // since the library can make things that will live arbitrarily long.
590 std::mem::forget(lib);
595 fn inject_panic_runtime(&mut self, krate: &ast::Crate) {
596 // If we're only compiling an rlib, then there's no need to select a
597 // panic runtime, so we just skip this section entirely.
599 self.sess.crate_types.borrow().iter().any(|ct| *ct != config::CrateType::Rlib);
601 info!("panic runtime injection skipped, only generating rlib");
605 // If we need a panic runtime, we try to find an existing one here. At
606 // the same time we perform some general validation of the DAG we've got
607 // going such as ensuring everything has a compatible panic strategy.
609 // The logic for finding the panic runtime here is pretty much the same
610 // as the allocator case with the only addition that the panic strategy
611 // compilation mode also comes into play.
612 let desired_strategy = self.sess.panic_strategy();
613 let mut runtime_found = false;
614 let mut needs_panic_runtime = attr::contains_name(&krate.attrs, sym::needs_panic_runtime);
616 self.cstore.iter_crate_data(|cnum, data| {
617 needs_panic_runtime = needs_panic_runtime || data.needs_panic_runtime();
618 if data.is_panic_runtime() {
619 // Inject a dependency from all #![needs_panic_runtime] to this
620 // #![panic_runtime] crate.
621 self.inject_dependency_if(cnum, "a panic runtime", &|data| {
622 data.needs_panic_runtime()
624 runtime_found = runtime_found || data.dep_kind() == DepKind::Explicit;
628 // If an explicitly linked and matching panic runtime was found, or if
629 // we just don't need one at all, then we're done here and there's
630 // nothing else to do.
631 if !needs_panic_runtime || runtime_found {
635 // By this point we know that we (a) need a panic runtime and (b) no
636 // panic runtime was explicitly linked. Here we just load an appropriate
637 // default runtime for our panic strategy and then inject the
640 // We may resolve to an already loaded crate (as the crate may not have
641 // been explicitly linked prior to this) and we may re-inject
642 // dependencies again, but both of those situations are fine.
644 // Also note that we have yet to perform validation of the crate graph
645 // in terms of everyone has a compatible panic runtime format, that's
646 // performed later as part of the `dependency_format` module.
647 let name = match desired_strategy {
648 PanicStrategy::Unwind => Symbol::intern("panic_unwind"),
649 PanicStrategy::Abort => Symbol::intern("panic_abort"),
651 info!("panic runtime not found -- loading {}", name);
653 let cnum = self.resolve_crate(name, DUMMY_SP, DepKind::Implicit, None);
654 let data = self.cstore.get_crate_data(cnum);
656 // Sanity check the loaded crate to ensure it is indeed a panic runtime
657 // and the panic strategy is indeed what we thought it was.
658 if !data.is_panic_runtime() {
659 self.sess.err(&format!("the crate `{}` is not a panic runtime", name));
661 if data.panic_strategy() != desired_strategy {
662 self.sess.err(&format!(
663 "the crate `{}` does not have the panic \
666 desired_strategy.desc()
670 self.cstore.injected_panic_runtime = Some(cnum);
671 self.inject_dependency_if(cnum, "a panic runtime", &|data| data.needs_panic_runtime());
674 fn inject_profiler_runtime(&mut self) {
675 if self.sess.opts.debugging_opts.profile || self.sess.opts.cg.profile_generate.enabled() {
676 info!("loading profiler");
678 let name = Symbol::intern("profiler_builtins");
679 let cnum = self.resolve_crate(name, DUMMY_SP, DepKind::Implicit, None);
680 let data = self.cstore.get_crate_data(cnum);
682 // Sanity check the loaded crate to ensure it is indeed a profiler runtime
683 if !data.is_profiler_runtime() {
684 self.sess.err(&format!(
685 "the crate `profiler_builtins` is not \
692 fn inject_allocator_crate(&mut self, krate: &ast::Crate) {
693 self.cstore.has_global_allocator = match &*global_allocator_spans(krate) {
694 [span1, span2, ..] => {
696 .struct_span_err(*span2, "cannot define multiple global allocators")
697 .span_label(*span2, "cannot define a new global allocator")
698 .span_label(*span1, "previous global allocator is defined here")
702 spans => !spans.is_empty(),
705 // Check to see if we actually need an allocator. This desire comes
706 // about through the `#![needs_allocator]` attribute and is typically
707 // written down in liballoc.
708 let mut needs_allocator = attr::contains_name(&krate.attrs, sym::needs_allocator);
709 self.cstore.iter_crate_data(|_, data| {
710 needs_allocator = needs_allocator || data.needs_allocator();
712 if !needs_allocator {
716 // At this point we've determined that we need an allocator. Let's see
717 // if our compilation session actually needs an allocator based on what
719 let all_rlib = self.sess.crate_types.borrow().iter().all(|ct| match *ct {
720 config::CrateType::Rlib => true,
727 // Ok, we need an allocator. Not only that but we're actually going to
728 // create an artifact that needs one linked in. Let's go find the one
729 // that we're going to link in.
731 // First up we check for global allocators. Look at the crate graph here
732 // and see what's a global allocator, including if we ourselves are a
734 let mut global_allocator =
735 self.cstore.has_global_allocator.then(|| Symbol::intern("this crate"));
736 self.cstore.iter_crate_data(|_, data| {
737 if !data.has_global_allocator() {
740 match global_allocator {
741 Some(other_crate) => {
742 self.sess.err(&format!(
743 "the `#[global_allocator]` in {} \
744 conflicts with global \
750 None => global_allocator = Some(data.name()),
753 if global_allocator.is_some() {
754 self.cstore.allocator_kind = Some(AllocatorKind::Global);
758 // Ok we haven't found a global allocator but we still need an
759 // allocator. At this point our allocator request is typically fulfilled
760 // by the standard library, denoted by the `#![default_lib_allocator]`
762 let mut has_default = attr::contains_name(&krate.attrs, sym::default_lib_allocator);
763 self.cstore.iter_crate_data(|_, data| {
764 if data.has_default_lib_allocator() {
771 "no global memory allocator found but one is \
772 required; link to std or \
773 add `#[global_allocator]` to a static item \
774 that implements the GlobalAlloc trait.",
777 self.cstore.allocator_kind = Some(AllocatorKind::Default);
780 fn inject_dependency_if(
784 needs_dep: &dyn Fn(&CrateMetadata) -> bool,
786 // don't perform this validation if the session has errors, as one of
787 // those errors may indicate a circular dependency which could cause
788 // this to stack overflow.
789 if self.sess.has_errors() {
793 // Before we inject any dependencies, make sure we don't inject a
794 // circular dependency by validating that this crate doesn't
795 // transitively depend on any crates satisfying `needs_dep`.
796 for dep in self.cstore.crate_dependencies_in_reverse_postorder(krate) {
797 let data = self.cstore.get_crate_data(dep);
798 if needs_dep(&data) {
799 self.sess.err(&format!(
800 "the crate `{}` cannot depend \
801 on a crate that needs {}, but \
803 self.cstore.get_crate_data(krate).name(),
810 // All crates satisfying `needs_dep` do not explicitly depend on the
811 // crate provided for this compile, but in order for this compilation to
812 // be successfully linked we need to inject a dependency (to order the
813 // crates on the command line correctly).
814 self.cstore.iter_crate_data(|cnum, data| {
815 if !needs_dep(data) {
819 info!("injecting a dep from {} to {}", cnum, krate);
820 data.add_dependency(krate);
824 pub fn postprocess(&mut self, krate: &ast::Crate) {
825 self.inject_profiler_runtime();
826 self.inject_allocator_crate(krate);
827 self.inject_panic_runtime(krate);
829 if log_enabled!(log::Level::Info) {
830 dump_crates(&self.cstore);
834 pub fn process_extern_crate(
837 definitions: &Definitions,
840 ast::ItemKind::ExternCrate(orig_name) => {
842 "resolving extern crate stmt. ident: {} orig_name: {:?}",
843 item.ident, orig_name
845 let name = match orig_name {
847 crate::validate_crate_name(
854 None => item.ident.name,
856 let dep_kind = if attr::contains_name(&item.attrs, sym::no_link) {
857 DepKind::UnexportedMacrosOnly
862 let cnum = self.resolve_crate(name, item.span, dep_kind, None);
864 let def_id = definitions.opt_local_def_id(item.id).unwrap();
865 let path_len = definitions.def_path(def_id.index).data.len();
866 self.update_extern_crate(
869 src: ExternCrateSource::Extern(def_id),
872 dependency_of: LOCAL_CRATE,
881 pub fn process_path_extern(&mut self, name: Symbol, span: Span) -> CrateNum {
882 let cnum = self.resolve_crate(name, span, DepKind::Explicit, None);
884 self.update_extern_crate(
887 src: ExternCrateSource::Path,
889 // to have the least priority in `update_extern_crate`
890 path_len: usize::max_value(),
891 dependency_of: LOCAL_CRATE,
898 pub fn maybe_process_path_extern(&mut self, name: Symbol, span: Span) -> Option<CrateNum> {
899 self.maybe_resolve_crate(name, span, DepKind::Explicit, None).ok()