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
::utils
::CanonicalizedPath
;
228 use rustc_session
::{CrateDisambiguator, Session}
;
229 use rustc_span
::symbol
::{sym, Symbol}
;
230 use rustc_span
::Span
;
231 use rustc_target
::spec
::{Target, TargetTriple}
;
233 use snap
::read
::FrameDecoder
;
234 use std
::io
::{Read, Result as IoResult, Write}
;
236 use std
::path
::{Path, PathBuf}
;
237 use std
::{cmp, fmt, fs}
;
238 use tracing
::{debug, info, warn}
;
241 crate struct CrateLocator
<'a
> {
242 // Immutable per-session configuration.
244 metadata_loader
: &'a
dyn MetadataLoader
,
246 // Immutable per-search configuration.
248 exact_paths
: Vec
<CanonicalizedPath
>,
249 pub hash
: Option
<Svh
>,
250 pub host_hash
: Option
<Svh
>,
251 extra_filename
: Option
<&'a
str>,
252 pub target
: &'a Target
,
253 pub triple
: TargetTriple
,
254 pub filesearch
: FileSearch
<'a
>,
255 root
: Option
<&'a CratePaths
>,
256 pub is_proc_macro
: Option
<bool
>,
258 // Mutable in-progress state or output.
259 rejected_via_hash
: Vec
<CrateMismatch
>,
260 rejected_via_triple
: Vec
<CrateMismatch
>,
261 rejected_via_kind
: Vec
<CrateMismatch
>,
262 rejected_via_version
: Vec
<CrateMismatch
>,
263 rejected_via_filename
: Vec
<CrateMismatch
>,
267 crate struct CratePaths
{
273 crate fn new(name
: Symbol
, source
: CrateSource
) -> CratePaths
{
274 CratePaths { name, source }
278 #[derive(Copy, Clone, PartialEq)]
279 crate enum CrateFlavor
{
285 impl fmt
::Display
for CrateFlavor
{
286 fn fmt(&self, f
: &mut fmt
::Formatter
<'_
>) -> fmt
::Result
{
287 f
.write_str(match *self {
288 CrateFlavor
::Rlib
=> "rlib",
289 CrateFlavor
::Rmeta
=> "rmeta",
290 CrateFlavor
::Dylib
=> "dylib",
295 impl<'a
> CrateLocator
<'a
> {
298 metadata_loader
: &'a
dyn MetadataLoader
,
301 host_hash
: Option
<Svh
>,
302 extra_filename
: Option
<&'a
str>,
305 root
: Option
<&'a CratePaths
>,
306 is_proc_macro
: Option
<bool
>,
307 ) -> CrateLocator
<'a
> {
312 exact_paths
: if hash
.is_none() {
315 .get(&crate_name
.as_str())
317 .filter_map(|entry
| entry
.files())
322 // SVH being specified means this is a transitive dependency,
323 // so `--extern` options do not apply.
329 target
: if is_host { &sess.host }
else { &sess.target }
,
331 TargetTriple
::from_triple(config
::host_triple())
333 sess
.opts
.target_triple
.clone()
335 filesearch
: if is_host
{
336 sess
.host_filesearch(path_kind
)
338 sess
.target_filesearch(path_kind
)
342 rejected_via_hash
: Vec
::new(),
343 rejected_via_triple
: Vec
::new(),
344 rejected_via_kind
: Vec
::new(),
345 rejected_via_version
: Vec
::new(),
346 rejected_via_filename
: Vec
::new(),
350 crate fn reset(&mut self) {
351 self.rejected_via_hash
.clear();
352 self.rejected_via_triple
.clear();
353 self.rejected_via_kind
.clear();
354 self.rejected_via_version
.clear();
355 self.rejected_via_filename
.clear();
358 crate fn maybe_load_library_crate(&mut self) -> Result
<Option
<Library
>, CrateError
> {
359 if !self.exact_paths
.is_empty() {
360 return self.find_commandline_library();
362 let mut seen_paths
= FxHashSet
::default();
363 if let Some(extra_filename
) = self.extra_filename
{
364 if let library @
Some(_
) = self.find_library_crate(extra_filename
, &mut seen_paths
)?
{
368 self.find_library_crate("", &mut seen_paths
)
371 fn find_library_crate(
374 seen_paths
: &mut FxHashSet
<PathBuf
>,
375 ) -> Result
<Option
<Library
>, CrateError
> {
376 // want: crate_name.dir_part() + prefix + crate_name.file_part + "-"
377 let dylib_prefix
= format
!("{}{}{}", self.target
.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
.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
) && file
.ends_with(&self.target
.dll_suffix
) {
410 &file
[(dylib_prefix
.len())..(file
.len() - self.target
.dll_suffix
.len())],
414 if file
.starts_with(&staticlib_prefix
)
415 && file
.ends_with(&self.target
.staticlib_suffix
)
418 .push(CrateMismatch { path: spf.path.clone(), got: "static".to_string() }
);
420 return FileDoesntMatch
;
423 info
!("lib candidate: {}", spf
.path
.display());
425 let (rlibs
, rmetas
, dylibs
) = candidates
.entry(hash
.to_string()).or_default();
426 let path
= fs
::canonicalize(&spf
.path
).unwrap_or_else(|_
| spf
.path
.clone());
427 if seen_paths
.contains(&path
) {
428 return FileDoesntMatch
;
430 seen_paths
.insert(path
.clone());
432 CrateFlavor
::Rlib
=> rlibs
.insert(path
, kind
),
433 CrateFlavor
::Rmeta
=> rmetas
.insert(path
, kind
),
434 CrateFlavor
::Dylib
=> dylibs
.insert(path
, kind
),
438 self.rejected_via_kind
.extend(staticlibs
);
440 // We have now collected all known libraries into a set of candidates
441 // keyed of the filename hash listed. For each filename, we also have a
442 // list of rlibs/dylibs that apply. Here, we map each of these lists
443 // (per hash), to a Library candidate for returning.
445 // A Library candidate is created if the metadata for the set of
446 // libraries corresponds to the crate id and hash criteria that this
447 // search is being performed for.
448 let mut libraries
= FxHashMap
::default();
449 for (_hash
, (rlibs
, rmetas
, dylibs
)) in candidates
{
450 if let Some((svh
, lib
)) = self.extract_lib(rlibs
, rmetas
, dylibs
)?
{
451 libraries
.insert(svh
, lib
);
455 // Having now translated all relevant found hashes into libraries, see
456 // what we've got and figure out if we found multiple candidates for
458 match libraries
.len() {
460 1 => Ok(Some(libraries
.into_iter().next().unwrap().1)),
461 _
=> Err(CrateError
::MultipleMatchingCrates(self.crate_name
, libraries
)),
467 rlibs
: FxHashMap
<PathBuf
, PathKind
>,
468 rmetas
: FxHashMap
<PathBuf
, PathKind
>,
469 dylibs
: FxHashMap
<PathBuf
, PathKind
>,
470 ) -> Result
<Option
<(Svh
, Library
)>, CrateError
> {
472 // Order here matters, rmeta should come first. See comment in
473 // `extract_one` below.
474 let source
= CrateSource
{
475 rmeta
: self.extract_one(rmetas
, CrateFlavor
::Rmeta
, &mut slot
)?
,
476 rlib
: self.extract_one(rlibs
, CrateFlavor
::Rlib
, &mut slot
)?
,
477 dylib
: self.extract_one(dylibs
, CrateFlavor
::Dylib
, &mut slot
)?
,
479 Ok(slot
.map(|(svh
, metadata
)| (svh
, Library { source, metadata }
)))
482 fn needs_crate_flavor(&self, flavor
: CrateFlavor
) -> bool
{
483 if flavor
== CrateFlavor
::Dylib
&& self.is_proc_macro
== Some(true) {
487 // The all loop is because `--crate-type=rlib --crate-type=rlib` is
488 // legal and produces both inside this type.
489 let is_rlib
= self.sess
.crate_types().iter().all(|c
| *c
== CrateType
::Rlib
);
490 let needs_object_code
= self.sess
.opts
.output_types
.should_codegen();
491 // If we're producing an rlib, then we don't need object code.
492 // Or, if we're not producing object code, then we don't need it either
493 // (e.g., if we're a cdylib but emitting just metadata).
494 if is_rlib
|| !needs_object_code
{
495 flavor
== CrateFlavor
::Rmeta
497 // we need all flavors (perhaps not true, but what we do for now)
502 // Attempts to extract *one* library from the set `m`. If the set has no
503 // elements, `None` is returned. If the set has more than one element, then
504 // the errors and notes are emitted about the set of libraries.
506 // With only one library in the set, this function will extract it, and then
507 // read the metadata from it if `*slot` is `None`. If the metadata couldn't
508 // be read, it is assumed that the file isn't a valid rust library (no
509 // errors are emitted).
512 m
: FxHashMap
<PathBuf
, PathKind
>,
514 slot
: &mut Option
<(Svh
, MetadataBlob
)>,
515 ) -> Result
<Option
<(PathBuf
, PathKind
)>, CrateError
> {
516 // If we are producing an rlib, and we've already loaded metadata, then
517 // we should not attempt to discover further crate sources (unless we're
518 // locating a proc macro; exact logic is in needs_crate_flavor). This means
519 // that under -Zbinary-dep-depinfo we will not emit a dependency edge on
520 // the *unused* rlib, and by returning `None` here immediately we
521 // guarantee that we do indeed not use it.
523 // See also #68149 which provides more detail on why emitting the
524 // dependency on the rlib is a bad thing.
526 // We currently do not verify that these other sources are even in sync,
527 // and this is arguably a bug (see #10786), but because reading metadata
528 // is quite slow (especially from dylibs) we currently do not read it
529 // from the other crate sources.
531 if m
.is_empty() || !self.needs_crate_flavor(flavor
) {
533 } else if m
.len() == 1 {
534 return Ok(Some(m
.into_iter().next().unwrap()));
538 let mut ret
: Option
<(PathBuf
, PathKind
)> = None
;
539 let mut err_data
: Option
<Vec
<PathBuf
>> = None
;
540 for (lib
, kind
) in m
{
541 info
!("{} reading metadata from: {}", flavor
, lib
.display());
542 let (hash
, metadata
) =
543 match get_metadata_section(self.target
, flavor
, &lib
, self.metadata_loader
) {
545 if let Some(h
) = self.crate_matches(&blob
, &lib
) {
548 info
!("metadata mismatch");
553 warn
!("no metadata found: {}", err
);
557 // If we see multiple hashes, emit an error about duplicate candidates.
558 if slot
.as_ref().map_or(false, |s
| s
.0 != hash
) {
559 if let Some(candidates
) = err_data
{
560 return Err(CrateError
::MultipleCandidates(
566 err_data
= Some(vec
![ret
.as_ref().unwrap().0.clone()]);
569 if let Some(candidates
) = &mut err_data
{
570 candidates
.push(lib
);
574 // Ok so at this point we've determined that `(lib, kind)` above is
575 // a candidate crate to load, and that `slot` is either none (this
576 // is the first crate of its kind) or if some the previous path has
577 // the exact same hash (e.g., it's the exact same crate).
579 // In principle these two candidate crates are exactly the same so
580 // we can choose either of them to link. As a stupidly gross hack,
581 // however, we favor crate in the sysroot.
583 // You can find more info in rust-lang/rust#39518 and various linked
584 // issues, but the general gist is that during testing libstd the
585 // compilers has two candidates to choose from: one in the sysroot
586 // and one in the deps folder. These two crates are the exact same
587 // crate but if the compiler chooses the one in the deps folder
588 // it'll cause spurious errors on Windows.
590 // As a result, we favor the sysroot crate here. Note that the
591 // candidates are all canonicalized, so we canonicalize the sysroot
593 if let Some((prev
, _
)) = &ret
{
594 let sysroot
= &self.sess
.sysroot
;
595 let sysroot
= sysroot
.canonicalize().unwrap_or_else(|_
| sysroot
.to_path_buf());
596 if prev
.starts_with(&sysroot
) {
600 *slot
= Some((hash
, metadata
));
601 ret
= Some((lib
, kind
));
604 if let Some(candidates
) = err_data
{
605 Err(CrateError
::MultipleCandidates(self.crate_name
, flavor
, candidates
))
611 fn crate_matches(&mut self, metadata
: &MetadataBlob
, libpath
: &Path
) -> Option
<Svh
> {
612 let rustc_version
= rustc_version();
613 let found_version
= metadata
.get_rustc_version();
614 if found_version
!= rustc_version
{
615 info
!("Rejecting via version: expected {} got {}", rustc_version
, found_version
);
616 self.rejected_via_version
617 .push(CrateMismatch { path: libpath.to_path_buf(), got: found_version }
);
621 let root
= metadata
.get_root();
622 if let Some(expected_is_proc_macro
) = self.is_proc_macro
{
623 let is_proc_macro
= root
.is_proc_macro_crate();
624 if is_proc_macro
!= expected_is_proc_macro
{
626 "Rejecting via proc macro: expected {} got {}",
627 expected_is_proc_macro
, is_proc_macro
633 if self.exact_paths
.is_empty() && self.crate_name
!= root
.name() {
634 info
!("Rejecting via crate name");
638 if root
.triple() != &self.triple
{
639 info
!("Rejecting via crate triple: expected {} got {}", self.triple
, root
.triple());
640 self.rejected_via_triple
.push(CrateMismatch
{
641 path
: libpath
.to_path_buf(),
642 got
: root
.triple().to_string(),
647 let hash
= root
.hash();
648 if let Some(expected_hash
) = self.hash
{
649 if hash
!= expected_hash
{
650 info
!("Rejecting via hash: expected {} got {}", expected_hash
, hash
);
651 self.rejected_via_hash
652 .push(CrateMismatch { path: libpath.to_path_buf(), got: hash.to_string() }
);
660 fn find_commandline_library(&mut self) -> Result
<Option
<Library
>, CrateError
> {
661 // First, filter out all libraries that look suspicious. We only accept
662 // files which actually exist that have the correct naming scheme for
664 let mut rlibs
= FxHashMap
::default();
665 let mut rmetas
= FxHashMap
::default();
666 let mut dylibs
= FxHashMap
::default();
667 for loc
in &self.exact_paths
{
668 if !loc
.canonicalized().exists() {
669 return Err(CrateError
::ExternLocationNotExist(
671 loc
.original().clone(),
674 let file
= match loc
.original().file_name().and_then(|s
| s
.to_str()) {
677 return Err(CrateError
::ExternLocationNotFile(
679 loc
.original().clone(),
684 if file
.starts_with("lib") && (file
.ends_with(".rlib") || file
.ends_with(".rmeta"))
685 || file
.starts_with(&self.target
.dll_prefix
)
686 && file
.ends_with(&self.target
.dll_suffix
)
688 // Make sure there's at most one rlib and at most one dylib.
689 // Note to take care and match against the non-canonicalized name:
690 // some systems save build artifacts into content-addressed stores
691 // that do not preserve extensions, and then link to them using
692 // e.g. symbolic links. If we canonicalize too early, we resolve
693 // the symlink, the file type is lost and we might treat rlibs and
695 let loc_canon
= loc
.canonicalized().clone();
696 let loc
= loc
.original();
697 if loc
.file_name().unwrap().to_str().unwrap().ends_with(".rlib") {
698 rlibs
.insert(loc_canon
, PathKind
::ExternFlag
);
699 } else if loc
.file_name().unwrap().to_str().unwrap().ends_with(".rmeta") {
700 rmetas
.insert(loc_canon
, PathKind
::ExternFlag
);
702 dylibs
.insert(loc_canon
, PathKind
::ExternFlag
);
705 self.rejected_via_filename
706 .push(CrateMismatch { path: loc.original().clone(), got: String::new() }
);
710 // Extract the dylib/rlib/rmeta triple.
711 Ok(self.extract_lib(rlibs
, rmetas
, dylibs
)?
.map(|(_
, lib
)| lib
))
714 crate fn into_error(self) -> CrateError
{
715 CrateError
::LocatorCombined(CombinedLocatorError
{
716 crate_name
: self.crate_name
,
717 root
: self.root
.cloned(),
719 dll_prefix
: self.target
.dll_prefix
.clone(),
720 dll_suffix
: self.target
.dll_suffix
.clone(),
721 rejected_via_hash
: self.rejected_via_hash
,
722 rejected_via_triple
: self.rejected_via_triple
,
723 rejected_via_kind
: self.rejected_via_kind
,
724 rejected_via_version
: self.rejected_via_version
,
725 rejected_via_filename
: self.rejected_via_filename
,
730 /// A trivial wrapper for `Mmap` that implements `StableDeref`.
731 struct StableDerefMmap(memmap
::Mmap
);
733 impl Deref
for StableDerefMmap
{
736 fn deref(&self) -> &[u8] {
741 unsafe impl stable_deref_trait
::StableDeref
for StableDerefMmap {}
743 fn get_metadata_section(
747 loader
: &dyn MetadataLoader
,
748 ) -> Result
<MetadataBlob
, String
> {
749 if !filename
.exists() {
750 return Err(format
!("no such file: '{}'", filename
.display()));
752 let raw_bytes
: MetadataRef
= match flavor
{
753 CrateFlavor
::Rlib
=> loader
.get_rlib_metadata(target
, filename
)?
,
754 CrateFlavor
::Dylib
=> {
755 let buf
= loader
.get_dylib_metadata(target
, filename
)?
;
756 // The header is uncompressed
757 let header_len
= METADATA_HEADER
.len();
758 debug
!("checking {} bytes of metadata-version stamp", header_len
);
759 let header
= &buf
[..cmp
::min(header_len
, buf
.len())];
760 if header
!= METADATA_HEADER
{
762 "incompatible metadata version found: '{}'",
767 // Header is okay -> inflate the actual metadata
768 let compressed_bytes
= &buf
[header_len
..];
769 debug
!("inflating {} bytes of compressed metadata", compressed_bytes
.len());
770 let mut inflated
= Vec
::new();
771 match FrameDecoder
::new(compressed_bytes
).read_to_end(&mut inflated
) {
772 Ok(_
) => rustc_erase_owner
!(OwningRef
::new(inflated
).map_owner_box()),
774 return Err(format
!("failed to decompress metadata: {}", filename
.display()));
778 CrateFlavor
::Rmeta
=> {
779 // mmap the file, because only a small fraction of it is read.
780 let file
= std
::fs
::File
::open(filename
)
781 .map_err(|_
| format
!("failed to open rmeta metadata: '{}'", filename
.display()))?
;
782 let mmap
= unsafe { memmap::Mmap::map(&file) }
;
784 .map_err(|_
| format
!("failed to mmap rmeta metadata: '{}'", filename
.display()))?
;
786 rustc_erase_owner
!(OwningRef
::new(StableDerefMmap(mmap
)).map_owner_box())
789 let blob
= MetadataBlob
::new(raw_bytes
);
790 if blob
.is_compatible() {
793 Err(format
!("incompatible metadata version found: '{}'", filename
.display()))
797 /// Look for a plugin registrar. Returns its library path and crate disambiguator.
798 pub fn find_plugin_registrar(
800 metadata_loader
: &dyn MetadataLoader
,
803 ) -> (PathBuf
, CrateDisambiguator
) {
804 match find_plugin_registrar_impl(sess
, metadata_loader
, name
) {
806 Err(err
) => err
.report(sess
, span
),
810 fn find_plugin_registrar_impl
<'a
>(
812 metadata_loader
: &dyn MetadataLoader
,
814 ) -> Result
<(PathBuf
, CrateDisambiguator
), CrateError
> {
815 info
!("find plugin registrar `{}`", name
);
816 let mut locator
= CrateLocator
::new(
822 None
, // extra_filename
826 None
, // is_proc_macro
829 match locator
.maybe_load_library_crate()?
{
830 Some(library
) => match library
.source
.dylib
{
831 Some(dylib
) => Ok((dylib
.0, library
.metadata
.get_root().disambiguator())),
832 None
=> Err(CrateError
::NonDylibPlugin(name
)),
834 None
=> Err(locator
.into_error()),
838 /// A diagnostic function for dumping crate metadata to an output stream.
839 pub fn list_file_metadata(
842 metadata_loader
: &dyn MetadataLoader
,
845 let filename
= path
.file_name().unwrap().to_str().unwrap();
846 let flavor
= if filename
.ends_with(".rlib") {
848 } else if filename
.ends_with(".rmeta") {
853 match get_metadata_section(target
, flavor
, path
, metadata_loader
) {
854 Ok(metadata
) => metadata
.list_crate_metadata(out
),
855 Err(msg
) => write
!(out
, "{}\n", msg
),
859 // ------------------------------------------ Error reporting -------------------------------------
862 struct CrateMismatch
{
867 /// Candidate rejection reasons collected during crate search.
868 /// If no candidate is accepted, then these reasons are presented to the user,
869 /// otherwise they are ignored.
870 crate struct CombinedLocatorError
{
872 root
: Option
<CratePaths
>,
873 triple
: TargetTriple
,
876 rejected_via_hash
: Vec
<CrateMismatch
>,
877 rejected_via_triple
: Vec
<CrateMismatch
>,
878 rejected_via_kind
: Vec
<CrateMismatch
>,
879 rejected_via_version
: Vec
<CrateMismatch
>,
880 rejected_via_filename
: Vec
<CrateMismatch
>,
883 crate enum CrateError
{
884 NonAsciiName(Symbol
),
885 ExternLocationNotExist(Symbol
, PathBuf
),
886 ExternLocationNotFile(Symbol
, PathBuf
),
887 MultipleCandidates(Symbol
, CrateFlavor
, Vec
<PathBuf
>),
888 MultipleMatchingCrates(Symbol
, FxHashMap
<Svh
, Library
>),
889 SymbolConflictsCurrent(Symbol
),
890 SymbolConflictsOthers(Symbol
),
893 LocatorCombined(CombinedLocatorError
),
894 NonDylibPlugin(Symbol
),
898 crate fn report(self, sess
: &Session
, span
: Span
) -> ! {
899 let mut err
= match self {
900 CrateError
::NonAsciiName(crate_name
) => sess
.struct_span_err(
902 &format
!("cannot load a crate with a non-ascii name `{}`", crate_name
),
904 CrateError
::ExternLocationNotExist(crate_name
, loc
) => sess
.struct_span_err(
906 &format
!("extern location for {} does not exist: {}", crate_name
, loc
.display()),
908 CrateError
::ExternLocationNotFile(crate_name
, loc
) => sess
.struct_span_err(
910 &format
!("extern location for {} is not a file: {}", crate_name
, loc
.display()),
912 CrateError
::MultipleCandidates(crate_name
, flavor
, candidates
) => {
913 let mut err
= struct_span_err
!(
917 "multiple {} candidates for `{}` found",
921 for (i
, candidate
) in candidates
.iter().enumerate() {
922 err
.span_note(span
, &format
!("candidate #{}: {}", i
+ 1, candidate
.display()));
926 CrateError
::MultipleMatchingCrates(crate_name
, libraries
) => {
927 let mut err
= struct_span_err
!(
931 "multiple matching crates for `{}`",
934 let candidates
= libraries
936 .filter_map(|(_
, lib
)| {
937 let crate_name
= &lib
.metadata
.get_root().name().as_str();
938 match (&lib
.source
.dylib
, &lib
.source
.rlib
) {
939 (Some((pd
, _
)), Some((pr
, _
))) => Some(format
!(
940 "\ncrate `{}`: {}\n{:>padding$}",
944 padding
= 8 + crate_name
.len()
946 (Some((p
, _
)), None
) | (None
, Some((p
, _
))) => {
947 Some(format
!("\ncrate `{}`: {}", crate_name
, p
.display()))
949 (None
, None
) => None
,
952 .collect
::<String
>();
953 err
.note(&format
!("candidates:{}", candidates
));
956 CrateError
::SymbolConflictsCurrent(root_name
) => struct_span_err
!(
960 "the current crate is indistinguishable from one of its dependencies: it has the \
961 same crate-name `{}` and was compiled with the same `-C metadata` arguments. \
962 This will result in symbol conflicts between the two.",
965 CrateError
::SymbolConflictsOthers(root_name
) => struct_span_err
!(
969 "found two different crates with name `{}` that are not distinguished by differing \
970 `-C metadata`. This will result in symbol conflicts between the two.",
973 CrateError
::DlOpen(s
) | CrateError
::DlSym(s
) => sess
.struct_span_err(span
, &s
),
974 CrateError
::LocatorCombined(locator
) => {
975 let crate_name
= locator
.crate_name
;
976 let add
= match &locator
.root
{
977 None
=> String
::new(),
978 Some(r
) => format
!(" which `{}` depends on", r
.name
),
980 let mut msg
= "the following crate versions were found:".to_string();
981 let mut err
= if !locator
.rejected_via_hash
.is_empty() {
982 let mut err
= struct_span_err
!(
986 "found possibly newer version of crate `{}`{}",
990 err
.note("perhaps that crate needs to be recompiled?");
991 let mismatches
= locator
.rejected_via_hash
.iter();
992 for CrateMismatch { path, .. }
in mismatches
{
993 msg
.push_str(&format
!("\ncrate `{}`: {}", crate_name
, path
.display()));
995 if let Some(r
) = locator
.root
{
996 for path
in r
.source
.paths() {
997 msg
.push_str(&format
!("\ncrate `{}`: {}", r
.name
, path
.display()));
1002 } else if !locator
.rejected_via_triple
.is_empty() {
1003 let mut err
= struct_span_err
!(
1007 "couldn't find crate `{}` with expected target triple {}{}",
1012 let mismatches
= locator
.rejected_via_triple
.iter();
1013 for CrateMismatch { path, got }
in mismatches
{
1014 msg
.push_str(&format
!(
1015 "\ncrate `{}`, target triple {}: {}",
1023 } else if !locator
.rejected_via_kind
.is_empty() {
1024 let mut err
= struct_span_err
!(
1028 "found staticlib `{}` instead of rlib or dylib{}",
1032 err
.help("please recompile that crate using --crate-type lib");
1033 let mismatches
= locator
.rejected_via_kind
.iter();
1034 for CrateMismatch { path, .. }
in mismatches
{
1035 msg
.push_str(&format
!("\ncrate `{}`: {}", crate_name
, path
.display()));
1039 } else if !locator
.rejected_via_version
.is_empty() {
1040 let mut err
= struct_span_err
!(
1044 "found crate `{}` compiled by an incompatible version of rustc{}",
1049 "please recompile that crate using this compiler ({})",
1052 let mismatches
= locator
.rejected_via_version
.iter();
1053 for CrateMismatch { path, got }
in mismatches
{
1054 msg
.push_str(&format
!(
1055 "\ncrate `{}` compiled by {}: {}",
1064 let mut err
= struct_span_err
!(
1068 "can't find crate for `{}`{}",
1073 if (crate_name
== sym
::std
|| crate_name
== sym
::core
)
1074 && locator
.triple
!= TargetTriple
::from_triple(config
::host_triple())
1076 err
.note(&format
!("the `{}` target may not be installed", locator
.triple
));
1077 } else if crate_name
== sym
::profiler_builtins
{
1078 err
.note(&"the compiler may have been built without the profiler runtime");
1080 err
.span_label(span
, "can't find crate");
1084 if !locator
.rejected_via_filename
.is_empty() {
1085 let mismatches
= locator
.rejected_via_filename
.iter();
1086 for CrateMismatch { path, .. }
in mismatches
{
1088 "extern location for {} is of an unknown type: {}",
1093 "file name should be lib*.rlib or {}*.{}",
1094 locator
.dll_prefix
, locator
.dll_suffix
1100 CrateError
::NonDylibPlugin(crate_name
) => struct_span_err
!(
1104 "plugin `{}` only found in rlib format, but must be available in dylib format",
1110 sess
.abort_if_errors();