1 //! Finds crate binaries and loads their metadata
3 //! Might I be the first to welcome you to a world of platform differences,
4 //! version requirements, dependency graphs, conflicting desires, and fun! This
5 //! is the major guts (along with metadata::creader) of the compiler for loading
6 //! crates and resolving dependencies. Let's take a tour!
10 //! Each invocation of the compiler is immediately concerned with one primary
11 //! problem, to connect a set of crates to resolved crates on the filesystem.
12 //! Concretely speaking, the compiler follows roughly these steps to get here:
14 //! 1. Discover a set of `extern crate` statements.
15 //! 2. Transform these directives into crate names. If the directive does not
16 //! have an explicit name, then the identifier is the name.
17 //! 3. For each of these crate names, find a corresponding crate on the
20 //! Sounds easy, right? Let's walk into some of the nuances.
22 //! ## Transitive Dependencies
24 //! Let's say we've got three crates: A, B, and C. A depends on B, and B depends
25 //! on C. When we're compiling A, we primarily need to find and locate B, but we
26 //! also end up needing to find and locate C as well.
28 //! The reason for this is that any of B's types could be composed of C's types,
29 //! any function in B could return a type from C, etc. To be able to guarantee
30 //! that we can always type-check/translate any function, we have to have
31 //! complete knowledge of the whole ecosystem, not just our immediate
34 //! So now as part of the "find a corresponding crate on the filesystem" step
35 //! above, this involves also finding all crates for *all upstream
36 //! dependencies*. This includes all dependencies transitively.
38 //! ## Rlibs and Dylibs
40 //! The compiler has two forms of intermediate dependencies. These are dubbed
41 //! rlibs and dylibs for the static and dynamic variants, respectively. An rlib
42 //! is a rustc-defined file format (currently just an ar archive) while a dylib
43 //! is a platform-defined dynamic library. Each library has a metadata somewhere
46 //! A third kind of dependency is an rmeta file. These are metadata files and do
47 //! not contain any code, etc. To a first approximation, these are treated in the
48 //! same way as rlibs. Where there is both an rlib and an rmeta file, the rlib
49 //! gets priority (even if the rmeta file is newer). An rmeta file is only
50 //! useful for checking a downstream crate, attempting to link one will cause an
53 //! When translating a crate name to a crate on the filesystem, we all of a
54 //! sudden need to take into account both rlibs and dylibs! Linkage later on may
55 //! use either one of these files, as each has their pros/cons. The job of crate
56 //! loading is to discover what's possible by finding all candidates.
58 //! Most parts of this loading systems keep the dylib/rlib as just separate
63 //! We can't exactly scan your whole hard drive when looking for dependencies,
64 //! so we need to places to look. Currently the compiler will implicitly add the
65 //! target lib search path ($prefix/lib/rustlib/$target/lib) to any compilation,
66 //! and otherwise all -L flags are added to the search paths.
68 //! ## What criterion to select on?
70 //! This a pretty tricky area of loading crates. Given a file, how do we know
71 //! whether it's the right crate? Currently, the rules look along these lines:
73 //! 1. Does the filename match an rlib/dylib pattern? That is to say, does the
74 //! filename have the right prefix/suffix?
75 //! 2. Does the filename have the right prefix for the crate name being queried?
76 //! This is filtering for files like `libfoo*.rlib` and such. If the crate
77 //! we're looking for was originally compiled with -C extra-filename, the
78 //! extra filename will be included in this prefix to reduce reading
79 //! metadata from crates that would otherwise share our prefix.
80 //! 3. Is the file an actual rust library? This is done by loading the metadata
81 //! from the library and making sure it's actually there.
82 //! 4. Does the name in the metadata agree with the name of the library?
83 //! 5. Does the target in the metadata agree with the current target?
84 //! 6. Does the SVH match? (more on this later)
86 //! If the file answers `yes` to all these questions, then the file is
87 //! considered as being *candidate* for being accepted. It is illegal to have
88 //! more than two candidates as the compiler has no method by which to resolve
89 //! this conflict. Additionally, rlib/dylib candidates are considered
92 //! After all this has happened, we have 1 or two files as candidates. These
93 //! represent the rlib/dylib file found for a library, and they're returned as
96 //! ### What about versions?
98 //! A lot of effort has been put forth to remove versioning from the compiler.
99 //! There have been forays in the past to have versioning baked in, but it was
100 //! largely always deemed insufficient to the point that it was recognized that
101 //! it's probably something the compiler shouldn't do anyway due to its
102 //! complicated nature and the state of the half-baked solutions.
104 //! With a departure from versioning, the primary criterion for loading crates
105 //! is just the name of a crate. If we stopped here, it would imply that you
106 //! could never link two crates of the same name from different sources
107 //! together, which is clearly a bad state to be in.
109 //! To resolve this problem, we come to the next section!
113 //! A number of flags have been added to the compiler to solve the "version
114 //! problem" in the previous section, as well as generally enabling more
115 //! powerful usage of the crate loading system of the compiler. The goal of
116 //! these flags and options are to enable third-party tools to drive the
117 //! compiler with prior knowledge about how the world should look.
119 //! ## The `--extern` flag
121 //! The compiler accepts a flag of this form a number of times:
124 //! --extern crate-name=path/to/the/crate.rlib
127 //! This flag is basically the following letter to the compiler:
131 //! > When you are attempting to load the immediate dependency `crate-name`, I
132 //! > would like you to assume that the library is located at
133 //! > `path/to/the/crate.rlib`, and look nowhere else. Also, please do not
134 //! > assume that the path I specified has the name `crate-name`.
136 //! This flag basically overrides most matching logic except for validating that
137 //! the file is indeed a rust library. The same `crate-name` can be specified
138 //! twice to specify the rlib/dylib pair.
140 //! ## Enabling "multiple versions"
142 //! This basically boils down to the ability to specify arbitrary packages to
143 //! the compiler. For example, if crate A wanted to use Bv1 and Bv2, then it
144 //! would look something like:
146 //! ```compile_fail,E0463
153 //! and the compiler would be invoked as:
156 //! rustc a.rs --extern b1=path/to/libb1.rlib --extern b2=path/to/libb2.rlib
159 //! In this scenario there are two crates named `b` and the compiler must be
160 //! manually driven to be informed where each crate is.
162 //! ## Frobbing symbols
164 //! One of the immediate problems with linking the same library together twice
165 //! in the same problem is dealing with duplicate symbols. The primary way to
166 //! deal with this in rustc is to add hashes to the end of each symbol.
168 //! In order to force hashes to change between versions of a library, if
169 //! desired, the compiler exposes an option `-C metadata=foo`, which is used to
170 //! initially seed each symbol hash. The string `foo` is prepended to each
171 //! string-to-hash to ensure that symbols change over time.
173 //! ## Loading transitive dependencies
175 //! Dealing with same-named-but-distinct crates is not just a local problem, but
176 //! one that also needs to be dealt with for transitive dependencies. Note that
177 //! in the letter above `--extern` flags only apply to the *local* set of
178 //! dependencies, not the upstream transitive dependencies. Consider this
179 //! dependency graph:
191 //! In this scenario, when we compile `D`, we need to be able to distinctly
192 //! resolve `A.1` and `A.2`, but an `--extern` flag cannot apply to these
193 //! transitive dependencies.
195 //! Note that the key idea here is that `B` and `C` are both *already compiled*.
196 //! That is, they have already resolved their dependencies. Due to unrelated
197 //! technical reasons, when a library is compiled, it is only compatible with
198 //! the *exact same* version of the upstream libraries it was compiled against.
199 //! We use the "Strict Version Hash" to identify the exact copy of an upstream
202 //! With this knowledge, we know that `B` and `C` will depend on `A` with
203 //! different SVH values, so we crawl the normal `-L` paths looking for
204 //! `liba*.rlib` and filter based on the contained SVH.
206 //! In the end, this ends up not needing `--extern` to specify upstream
207 //! transitive dependencies.
211 //! That's the general overview of loading crates in the compiler, but it's by
212 //! no means all of the necessary details. Take a look at the rest of
213 //! metadata::locator or metadata::creader for all the juicy details!
215 use crate::creader::Library;
216 use crate::rmeta::{rustc_version, MetadataBlob, METADATA_HEADER};
218 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
219 use rustc_data_structures::owning_ref::OwningRef;
220 use rustc_data_structures::svh::Svh;
221 use rustc_data_structures::sync::MetadataRef;
222 use rustc_errors::struct_span_err;
223 use rustc_middle::middle::cstore::{CrateSource, MetadataLoader};
224 use rustc_session::config::{self, CrateType};
225 use rustc_session::filesearch::{FileDoesntMatch, FileMatches, FileSearch};
226 use rustc_session::search_paths::PathKind;
227 use rustc_session::{CrateDisambiguator, Session};
228 use rustc_span::symbol::{sym, Symbol};
229 use rustc_span::Span;
230 use rustc_target::spec::{Target, TargetTriple};
232 use flate2::read::DeflateDecoder;
233 use log::{debug, info, warn};
234 use std::io::{Read, Result as IoResult, Write};
236 use std::path::{Path, PathBuf};
237 use std::{cmp, fmt, fs};
240 crate struct CrateLocator<'a> {
241 // Immutable per-session configuration.
243 metadata_loader: &'a dyn MetadataLoader,
245 // Immutable per-search configuration.
247 exact_paths: Vec<PathBuf>,
248 pub hash: Option<Svh>,
249 pub host_hash: Option<Svh>,
250 extra_filename: Option<&'a str>,
251 pub target: &'a Target,
252 pub triple: TargetTriple,
253 pub filesearch: FileSearch<'a>,
254 root: Option<&'a CratePaths>,
255 pub is_proc_macro: Option<bool>,
257 // Mutable in-progress state or output.
258 rejected_via_hash: Vec<CrateMismatch>,
259 rejected_via_triple: Vec<CrateMismatch>,
260 rejected_via_kind: Vec<CrateMismatch>,
261 rejected_via_version: Vec<CrateMismatch>,
262 rejected_via_filename: Vec<CrateMismatch>,
266 crate struct CratePaths {
272 crate fn new(name: Symbol, source: CrateSource) -> CratePaths {
273 CratePaths { name, source }
277 #[derive(Copy, Clone, PartialEq)]
278 crate enum CrateFlavor {
284 impl fmt::Display for CrateFlavor {
285 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
286 f.write_str(match *self {
287 CrateFlavor::Rlib => "rlib",
288 CrateFlavor::Rmeta => "rmeta",
289 CrateFlavor::Dylib => "dylib",
294 impl<'a> CrateLocator<'a> {
297 metadata_loader: &'a dyn MetadataLoader,
300 host_hash: Option<Svh>,
301 extra_filename: Option<&'a str>,
304 root: Option<&'a CratePaths>,
305 is_proc_macro: Option<bool>,
306 ) -> CrateLocator<'a> {
311 exact_paths: if hash.is_none() {
314 .get(&crate_name.as_str())
316 .filter_map(|entry| entry.files())
321 // SVH being specified means this is a transitive dependency,
322 // so `--extern` options do not apply.
328 target: if is_host { &sess.host } else { &sess.target.target },
330 TargetTriple::from_triple(config::host_triple())
332 sess.opts.target_triple.clone()
334 filesearch: if is_host {
335 sess.host_filesearch(path_kind)
337 sess.target_filesearch(path_kind)
341 rejected_via_hash: Vec::new(),
342 rejected_via_triple: Vec::new(),
343 rejected_via_kind: Vec::new(),
344 rejected_via_version: Vec::new(),
345 rejected_via_filename: Vec::new(),
349 crate fn reset(&mut self) {
350 self.rejected_via_hash.clear();
351 self.rejected_via_triple.clear();
352 self.rejected_via_kind.clear();
353 self.rejected_via_version.clear();
354 self.rejected_via_filename.clear();
357 crate fn maybe_load_library_crate(&mut self) -> Result<Option<Library>, CrateError> {
358 if !self.exact_paths.is_empty() {
359 return self.find_commandline_library();
361 let mut seen_paths = FxHashSet::default();
362 if let Some(extra_filename) = self.extra_filename {
363 if let library @ Some(_) = self.find_library_crate(extra_filename, &mut seen_paths)? {
367 self.find_library_crate("", &mut seen_paths)
370 fn find_library_crate(
373 seen_paths: &mut FxHashSet<PathBuf>,
374 ) -> Result<Option<Library>, CrateError> {
375 // want: crate_name.dir_part() + prefix + crate_name.file_part + "-"
377 format!("{}{}{}", self.target.options.dll_prefix, self.crate_name, extra_prefix);
378 let rlib_prefix = format!("lib{}{}", self.crate_name, extra_prefix);
379 let staticlib_prefix =
380 format!("{}{}{}", self.target.options.staticlib_prefix, self.crate_name, extra_prefix);
382 let mut candidates: FxHashMap<_, (FxHashMap<_, _>, FxHashMap<_, _>, FxHashMap<_, _>)> =
384 let mut staticlibs = vec![];
386 // First, find all possible candidate rlibs and dylibs purely based on
387 // the name of the files themselves. We're trying to match against an
388 // exact crate name and a possibly an exact hash.
390 // During this step, we can filter all found libraries based on the
391 // name and id found in the crate id (we ignore the path portion for
392 // filename matching), as well as the exact hash (if specified). If we
393 // end up having many candidates, we must look at the metadata to
394 // perform exact matches against hashes/crate ids. Note that opening up
395 // the metadata is where we do an exact match against the full contents
396 // of the crate id (path/name/id).
398 // The goal of this step is to look at as little metadata as possible.
399 self.filesearch.search(|spf, kind| {
400 let file = match &spf.file_name_str {
401 None => return FileDoesntMatch,
404 let (hash, found_kind) = if file.starts_with(&rlib_prefix) && file.ends_with(".rlib") {
405 (&file[(rlib_prefix.len())..(file.len() - ".rlib".len())], CrateFlavor::Rlib)
406 } else if file.starts_with(&rlib_prefix) && file.ends_with(".rmeta") {
407 (&file[(rlib_prefix.len())..(file.len() - ".rmeta".len())], CrateFlavor::Rmeta)
408 } else if file.starts_with(&dylib_prefix)
409 && file.ends_with(&self.target.options.dll_suffix)
413 [(dylib_prefix.len())..(file.len() - self.target.options.dll_suffix.len())],
417 if file.starts_with(&staticlib_prefix)
418 && file.ends_with(&self.target.options.staticlib_suffix)
421 .push(CrateMismatch { path: spf.path.clone(), got: "static".to_string() });
423 return FileDoesntMatch;
426 info!("lib candidate: {}", spf.path.display());
428 let (rlibs, rmetas, dylibs) = candidates.entry(hash.to_string()).or_default();
429 let path = fs::canonicalize(&spf.path).unwrap_or_else(|_| spf.path.clone());
430 if seen_paths.contains(&path) {
431 return FileDoesntMatch;
433 seen_paths.insert(path.clone());
435 CrateFlavor::Rlib => rlibs.insert(path, kind),
436 CrateFlavor::Rmeta => rmetas.insert(path, kind),
437 CrateFlavor::Dylib => dylibs.insert(path, kind),
441 self.rejected_via_kind.extend(staticlibs);
443 // We have now collected all known libraries into a set of candidates
444 // keyed of the filename hash listed. For each filename, we also have a
445 // list of rlibs/dylibs that apply. Here, we map each of these lists
446 // (per hash), to a Library candidate for returning.
448 // A Library candidate is created if the metadata for the set of
449 // libraries corresponds to the crate id and hash criteria that this
450 // search is being performed for.
451 let mut libraries = FxHashMap::default();
452 for (_hash, (rlibs, rmetas, dylibs)) in candidates {
453 if let Some((svh, lib)) = self.extract_lib(rlibs, rmetas, dylibs)? {
454 libraries.insert(svh, lib);
458 // Having now translated all relevant found hashes into libraries, see
459 // what we've got and figure out if we found multiple candidates for
461 match libraries.len() {
463 1 => Ok(Some(libraries.into_iter().next().unwrap().1)),
464 _ => Err(CrateError::MultipleMatchingCrates(self.crate_name, libraries)),
470 rlibs: FxHashMap<PathBuf, PathKind>,
471 rmetas: FxHashMap<PathBuf, PathKind>,
472 dylibs: FxHashMap<PathBuf, PathKind>,
473 ) -> Result<Option<(Svh, Library)>, CrateError> {
475 // Order here matters, rmeta should come first. See comment in
476 // `extract_one` below.
477 let source = CrateSource {
478 rmeta: self.extract_one(rmetas, CrateFlavor::Rmeta, &mut slot)?,
479 rlib: self.extract_one(rlibs, CrateFlavor::Rlib, &mut slot)?,
480 dylib: self.extract_one(dylibs, CrateFlavor::Dylib, &mut slot)?,
482 Ok(slot.map(|(svh, metadata)| (svh, Library { source, metadata })))
485 fn needs_crate_flavor(&self, flavor: CrateFlavor) -> bool {
486 if flavor == CrateFlavor::Dylib && self.is_proc_macro == Some(true) {
490 // The all loop is because `--crate-type=rlib --crate-type=rlib` is
491 // legal and produces both inside this type.
492 let is_rlib = self.sess.crate_types().iter().all(|c| *c == CrateType::Rlib);
493 let needs_object_code = self.sess.opts.output_types.should_codegen();
494 // If we're producing an rlib, then we don't need object code.
495 // Or, if we're not producing object code, then we don't need it either
496 // (e.g., if we're a cdylib but emitting just metadata).
497 if is_rlib || !needs_object_code {
498 flavor == CrateFlavor::Rmeta
500 // we need all flavors (perhaps not true, but what we do for now)
505 // Attempts to extract *one* library from the set `m`. If the set has no
506 // elements, `None` is returned. If the set has more than one element, then
507 // the errors and notes are emitted about the set of libraries.
509 // With only one library in the set, this function will extract it, and then
510 // read the metadata from it if `*slot` is `None`. If the metadata couldn't
511 // be read, it is assumed that the file isn't a valid rust library (no
512 // errors are emitted).
515 m: FxHashMap<PathBuf, PathKind>,
517 slot: &mut Option<(Svh, MetadataBlob)>,
518 ) -> Result<Option<(PathBuf, PathKind)>, CrateError> {
519 // If we are producing an rlib, and we've already loaded metadata, then
520 // we should not attempt to discover further crate sources (unless we're
521 // locating a proc macro; exact logic is in needs_crate_flavor). This means
522 // that under -Zbinary-dep-depinfo we will not emit a dependency edge on
523 // the *unused* rlib, and by returning `None` here immediately we
524 // guarantee that we do indeed not use it.
526 // See also #68149 which provides more detail on why emitting the
527 // dependency on the rlib is a bad thing.
529 // We currently do not verify that these other sources are even in sync,
530 // and this is arguably a bug (see #10786), but because reading metadata
531 // is quite slow (especially from dylibs) we currently do not read it
532 // from the other crate sources.
534 if m.is_empty() || !self.needs_crate_flavor(flavor) {
536 } else if m.len() == 1 {
537 return Ok(Some(m.into_iter().next().unwrap()));
541 let mut ret: Option<(PathBuf, PathKind)> = None;
542 let mut err_data: Option<Vec<PathBuf>> = None;
543 for (lib, kind) in m {
544 info!("{} reading metadata from: {}", flavor, lib.display());
545 let (hash, metadata) =
546 match get_metadata_section(self.target, flavor, &lib, self.metadata_loader) {
548 if let Some(h) = self.crate_matches(&blob, &lib) {
551 info!("metadata mismatch");
556 warn!("no metadata found: {}", err);
560 // If we see multiple hashes, emit an error about duplicate candidates.
561 if slot.as_ref().map_or(false, |s| s.0 != hash) {
562 if let Some(candidates) = err_data {
563 return Err(CrateError::MultipleCandidates(
569 err_data = Some(vec![ret.as_ref().unwrap().0.clone()]);
572 if let Some(candidates) = &mut err_data {
573 candidates.push(lib);
577 // Ok so at this point we've determined that `(lib, kind)` above is
578 // a candidate crate to load, and that `slot` is either none (this
579 // is the first crate of its kind) or if some the previous path has
580 // the exact same hash (e.g., it's the exact same crate).
582 // In principle these two candidate crates are exactly the same so
583 // we can choose either of them to link. As a stupidly gross hack,
584 // however, we favor crate in the sysroot.
586 // You can find more info in rust-lang/rust#39518 and various linked
587 // issues, but the general gist is that during testing libstd the
588 // compilers has two candidates to choose from: one in the sysroot
589 // and one in the deps folder. These two crates are the exact same
590 // crate but if the compiler chooses the one in the deps folder
591 // it'll cause spurious errors on Windows.
593 // As a result, we favor the sysroot crate here. Note that the
594 // candidates are all canonicalized, so we canonicalize the sysroot
596 if let Some((prev, _)) = &ret {
597 let sysroot = &self.sess.sysroot;
598 let sysroot = sysroot.canonicalize().unwrap_or_else(|_| sysroot.to_path_buf());
599 if prev.starts_with(&sysroot) {
603 *slot = Some((hash, metadata));
604 ret = Some((lib, kind));
607 if let Some(candidates) = err_data {
608 Err(CrateError::MultipleCandidates(self.crate_name, flavor, candidates))
614 fn crate_matches(&mut self, metadata: &MetadataBlob, libpath: &Path) -> Option<Svh> {
615 let rustc_version = rustc_version();
616 let found_version = metadata.get_rustc_version();
617 if found_version != rustc_version {
618 info!("Rejecting via version: expected {} got {}", rustc_version, found_version);
619 self.rejected_via_version
620 .push(CrateMismatch { path: libpath.to_path_buf(), got: found_version });
624 let root = metadata.get_root();
625 if let Some(expected_is_proc_macro) = self.is_proc_macro {
626 let is_proc_macro = root.is_proc_macro_crate();
627 if is_proc_macro != expected_is_proc_macro {
629 "Rejecting via proc macro: expected {} got {}",
630 expected_is_proc_macro, is_proc_macro
636 if self.exact_paths.is_empty() {
637 if self.crate_name != root.name() {
638 info!("Rejecting via crate name");
643 if root.triple() != &self.triple {
644 info!("Rejecting via crate triple: expected {} got {}", self.triple, root.triple());
645 self.rejected_via_triple.push(CrateMismatch {
646 path: libpath.to_path_buf(),
647 got: root.triple().to_string(),
652 let hash = root.hash();
653 if let Some(expected_hash) = self.hash {
654 if hash != expected_hash {
655 info!("Rejecting via hash: expected {} got {}", expected_hash, hash);
656 self.rejected_via_hash
657 .push(CrateMismatch { path: libpath.to_path_buf(), got: hash.to_string() });
665 fn find_commandline_library(&mut self) -> Result<Option<Library>, CrateError> {
666 // First, filter out all libraries that look suspicious. We only accept
667 // files which actually exist that have the correct naming scheme for
669 let mut rlibs = FxHashMap::default();
670 let mut rmetas = FxHashMap::default();
671 let mut dylibs = FxHashMap::default();
672 for loc in &self.exact_paths {
674 return Err(CrateError::ExternLocationNotExist(self.crate_name, loc.clone()));
676 let file = match loc.file_name().and_then(|s| s.to_str()) {
679 return Err(CrateError::ExternLocationNotFile(self.crate_name, loc.clone()));
683 if file.starts_with("lib") && (file.ends_with(".rlib") || file.ends_with(".rmeta"))
684 || file.starts_with(&self.target.options.dll_prefix)
685 && file.ends_with(&self.target.options.dll_suffix)
687 // Make sure there's at most one rlib and at most one dylib.
688 let loc = fs::canonicalize(&loc).unwrap_or_else(|_| loc.clone());
689 if loc.file_name().unwrap().to_str().unwrap().ends_with(".rlib") {
690 rlibs.insert(loc, PathKind::ExternFlag);
691 } else if loc.file_name().unwrap().to_str().unwrap().ends_with(".rmeta") {
692 rmetas.insert(loc, PathKind::ExternFlag);
694 dylibs.insert(loc, PathKind::ExternFlag);
697 self.rejected_via_filename
698 .push(CrateMismatch { path: loc.clone(), got: String::new() });
702 // Extract the dylib/rlib/rmeta triple.
703 Ok(self.extract_lib(rlibs, rmetas, dylibs)?.map(|(_, lib)| lib))
706 crate fn into_error(self) -> CrateError {
707 CrateError::LocatorCombined(CombinedLocatorError {
708 crate_name: self.crate_name,
709 root: self.root.cloned(),
711 dll_prefix: self.target.options.dll_prefix.clone(),
712 dll_suffix: self.target.options.dll_suffix.clone(),
713 rejected_via_hash: self.rejected_via_hash,
714 rejected_via_triple: self.rejected_via_triple,
715 rejected_via_kind: self.rejected_via_kind,
716 rejected_via_version: self.rejected_via_version,
717 rejected_via_filename: self.rejected_via_filename,
722 /// A trivial wrapper for `Mmap` that implements `StableDeref`.
723 struct StableDerefMmap(memmap::Mmap);
725 impl Deref for StableDerefMmap {
728 fn deref(&self) -> &[u8] {
733 unsafe impl stable_deref_trait::StableDeref for StableDerefMmap {}
735 fn get_metadata_section(
739 loader: &dyn MetadataLoader,
740 ) -> Result<MetadataBlob, String> {
741 if !filename.exists() {
742 return Err(format!("no such file: '{}'", filename.display()));
744 let raw_bytes: MetadataRef = match flavor {
745 CrateFlavor::Rlib => loader.get_rlib_metadata(target, filename)?,
746 CrateFlavor::Dylib => {
747 let buf = loader.get_dylib_metadata(target, filename)?;
748 // The header is uncompressed
749 let header_len = METADATA_HEADER.len();
750 debug!("checking {} bytes of metadata-version stamp", header_len);
751 let header = &buf[..cmp::min(header_len, buf.len())];
752 if header != METADATA_HEADER {
754 "incompatible metadata version found: '{}'",
759 // Header is okay -> inflate the actual metadata
760 let compressed_bytes = &buf[header_len..];
761 debug!("inflating {} bytes of compressed metadata", compressed_bytes.len());
762 let mut inflated = Vec::new();
763 match DeflateDecoder::new(compressed_bytes).read_to_end(&mut inflated) {
764 Ok(_) => rustc_erase_owner!(OwningRef::new(inflated).map_owner_box()),
766 return Err(format!("failed to decompress metadata: {}", filename.display()));
770 CrateFlavor::Rmeta => {
771 // mmap the file, because only a small fraction of it is read.
772 let file = std::fs::File::open(filename)
773 .map_err(|_| format!("failed to open rmeta metadata: '{}'", filename.display()))?;
774 let mmap = unsafe { memmap::Mmap::map(&file) };
776 .map_err(|_| format!("failed to mmap rmeta metadata: '{}'", filename.display()))?;
778 rustc_erase_owner!(OwningRef::new(StableDerefMmap(mmap)).map_owner_box())
781 let blob = MetadataBlob::new(raw_bytes);
782 if blob.is_compatible() {
785 Err(format!("incompatible metadata version found: '{}'", filename.display()))
789 /// Look for a plugin registrar. Returns its library path and crate disambiguator.
790 pub fn find_plugin_registrar(
792 metadata_loader: &dyn MetadataLoader,
795 ) -> (PathBuf, CrateDisambiguator) {
796 match find_plugin_registrar_impl(sess, metadata_loader, name) {
798 Err(err) => err.report(sess, span),
802 fn find_plugin_registrar_impl<'a>(
804 metadata_loader: &dyn MetadataLoader,
806 ) -> Result<(PathBuf, CrateDisambiguator), CrateError> {
807 info!("find plugin registrar `{}`", name);
808 let mut locator = CrateLocator::new(
814 None, // extra_filename
818 None, // is_proc_macro
821 match locator.maybe_load_library_crate()? {
822 Some(library) => match library.source.dylib {
823 Some(dylib) => Ok((dylib.0, library.metadata.get_root().disambiguator())),
824 None => Err(CrateError::NonDylibPlugin(name)),
826 None => Err(locator.into_error()),
830 /// A diagnostic function for dumping crate metadata to an output stream.
831 pub fn list_file_metadata(
834 metadata_loader: &dyn MetadataLoader,
837 let filename = path.file_name().unwrap().to_str().unwrap();
838 let flavor = if filename.ends_with(".rlib") {
840 } else if filename.ends_with(".rmeta") {
845 match get_metadata_section(target, flavor, path, metadata_loader) {
846 Ok(metadata) => metadata.list_crate_metadata(out),
847 Err(msg) => write!(out, "{}\n", msg),
851 // ------------------------------------------ Error reporting -------------------------------------
854 struct CrateMismatch {
859 /// Candidate rejection reasons collected during crate search.
860 /// If no candidate is accepted, then these reasons are presented to the user,
861 /// otherwise they are ignored.
862 crate struct CombinedLocatorError {
864 root: Option<CratePaths>,
865 triple: TargetTriple,
868 rejected_via_hash: Vec<CrateMismatch>,
869 rejected_via_triple: Vec<CrateMismatch>,
870 rejected_via_kind: Vec<CrateMismatch>,
871 rejected_via_version: Vec<CrateMismatch>,
872 rejected_via_filename: Vec<CrateMismatch>,
875 crate enum CrateError {
876 NonAsciiName(Symbol),
877 ExternLocationNotExist(Symbol, PathBuf),
878 ExternLocationNotFile(Symbol, PathBuf),
879 MultipleCandidates(Symbol, CrateFlavor, Vec<PathBuf>),
880 MultipleMatchingCrates(Symbol, FxHashMap<Svh, Library>),
881 SymbolConflictsCurrent(Symbol),
882 SymbolConflictsOthers(Symbol),
885 LocatorCombined(CombinedLocatorError),
886 NonDylibPlugin(Symbol),
890 crate fn report(self, sess: &Session, span: Span) -> ! {
891 let mut err = match self {
892 CrateError::NonAsciiName(crate_name) => sess.struct_span_err(
894 &format!("cannot load a crate with a non-ascii name `{}`", crate_name),
896 CrateError::ExternLocationNotExist(crate_name, loc) => sess.struct_span_err(
898 &format!("extern location for {} does not exist: {}", crate_name, loc.display()),
900 CrateError::ExternLocationNotFile(crate_name, loc) => sess.struct_span_err(
902 &format!("extern location for {} is not a file: {}", crate_name, loc.display()),
904 CrateError::MultipleCandidates(crate_name, flavor, candidates) => {
905 let mut err = struct_span_err!(
909 "multiple {} candidates for `{}` found",
913 for (i, candidate) in candidates.iter().enumerate() {
914 err.span_note(span, &format!("candidate #{}: {}", i + 1, candidate.display()));
918 CrateError::MultipleMatchingCrates(crate_name, libraries) => {
919 let mut err = struct_span_err!(
923 "multiple matching crates for `{}`",
926 let candidates = libraries
928 .filter_map(|(_, lib)| {
929 let crate_name = &lib.metadata.get_root().name().as_str();
930 match (&lib.source.dylib, &lib.source.rlib) {
931 (Some((pd, _)), Some((pr, _))) => Some(format!(
932 "\ncrate `{}`: {}\n{:>padding$}",
936 padding = 8 + crate_name.len()
938 (Some((p, _)), None) | (None, Some((p, _))) => {
939 Some(format!("\ncrate `{}`: {}", crate_name, p.display()))
941 (None, None) => None,
944 .collect::<String>();
945 err.note(&format!("candidates:{}", candidates));
948 CrateError::SymbolConflictsCurrent(root_name) => struct_span_err!(
952 "the current crate is indistinguishable from one of its dependencies: it has the \
953 same crate-name `{}` and was compiled with the same `-C metadata` arguments. \
954 This will result in symbol conflicts between the two.",
957 CrateError::SymbolConflictsOthers(root_name) => struct_span_err!(
961 "found two different crates with name `{}` that are not distinguished by differing \
962 `-C metadata`. This will result in symbol conflicts between the two.",
965 CrateError::DlOpen(s) | CrateError::DlSym(s) => sess.struct_span_err(span, &s),
966 CrateError::LocatorCombined(locator) => {
967 let crate_name = locator.crate_name;
968 let add = match &locator.root {
969 None => String::new(),
970 Some(r) => format!(" which `{}` depends on", r.name),
972 let mut msg = "the following crate versions were found:".to_string();
973 let mut err = if !locator.rejected_via_hash.is_empty() {
974 let mut err = struct_span_err!(
978 "found possibly newer version of crate `{}`{}",
982 err.note("perhaps that crate needs to be recompiled?");
983 let mismatches = locator.rejected_via_hash.iter();
984 for CrateMismatch { path, .. } in mismatches {
985 msg.push_str(&format!("\ncrate `{}`: {}", crate_name, path.display()));
987 if let Some(r) = locator.root {
988 for path in r.source.paths() {
989 msg.push_str(&format!("\ncrate `{}`: {}", r.name, path.display()));
994 } else if !locator.rejected_via_triple.is_empty() {
995 let mut err = struct_span_err!(
999 "couldn't find crate `{}` with expected target triple {}{}",
1004 let mismatches = locator.rejected_via_triple.iter();
1005 for CrateMismatch { path, got } in mismatches {
1006 msg.push_str(&format!(
1007 "\ncrate `{}`, target triple {}: {}",
1015 } else if !locator.rejected_via_kind.is_empty() {
1016 let mut err = struct_span_err!(
1020 "found staticlib `{}` instead of rlib or dylib{}",
1024 err.help("please recompile that crate using --crate-type lib");
1025 let mismatches = locator.rejected_via_kind.iter();
1026 for CrateMismatch { path, .. } in mismatches {
1027 msg.push_str(&format!("\ncrate `{}`: {}", crate_name, path.display()));
1031 } else if !locator.rejected_via_version.is_empty() {
1032 let mut err = struct_span_err!(
1036 "found crate `{}` compiled by an incompatible version of rustc{}",
1041 "please recompile that crate using this compiler ({})",
1044 let mismatches = locator.rejected_via_version.iter();
1045 for CrateMismatch { path, got } in mismatches {
1046 msg.push_str(&format!(
1047 "\ncrate `{}` compiled by {}: {}",
1056 let mut err = struct_span_err!(
1060 "can't find crate for `{}`{}",
1065 if (crate_name == sym::std || crate_name == sym::core)
1066 && locator.triple != TargetTriple::from_triple(config::host_triple())
1068 err.note(&format!("the `{}` target may not be installed", locator.triple));
1069 } else if crate_name == sym::profiler_builtins {
1070 err.note(&"the compiler may have been built without the profiler runtime");
1072 err.span_label(span, "can't find crate");
1076 if !locator.rejected_via_filename.is_empty() {
1077 let mismatches = locator.rejected_via_filename.iter();
1078 for CrateMismatch { path, .. } in mismatches {
1080 "extern location for {} is of an unknown type: {}",
1085 "file name should be lib*.rlib or {}*.{}",
1086 locator.dll_prefix, locator.dll_suffix
1092 CrateError::NonDylibPlugin(crate_name) => struct_span_err!(
1096 "plugin `{}` only found in rlib format, but must be available in dylib format",
1102 sess.abort_if_errors();