1 // Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 use super::archive::{ArchiveBuilder, ArchiveConfig};
12 use super::linker::Linker;
13 use super::rpath::RPathConfig;
15 use metadata::METADATA_FILENAME;
16 use rustc::session::config::{self, NoDebugInfo, OutputFilenames, Input, OutputType};
17 use rustc::session::filesearch;
18 use rustc::session::search_paths::PathKind;
19 use rustc::session::Session;
20 use rustc::middle::cstore::{self, LinkMeta, NativeLibrary, LibSource, LinkagePreference,
22 use rustc::middle::dependency_format::Linkage;
24 use rustc::util::common::time;
25 use rustc::util::fs::fix_windows_verbatim_for_gcc;
26 use rustc::dep_graph::{DepKind, DepNode};
27 use rustc::hir::def_id::CrateNum;
28 use rustc::hir::svh::Svh;
29 use rustc_back::tempdir::TempDir;
30 use rustc_back::PanicStrategy;
31 use rustc_incremental::IncrementalHashesMap;
32 use context::get_reloc_model;
38 use std::ffi::OsString;
40 use std::io::{self, Read, Write};
42 use std::path::{Path, PathBuf};
43 use std::process::Command;
45 use flate2::Compression;
46 use flate2::write::ZlibEncoder;
51 /// The LLVM module name containing crate-metadata. This includes a `.` on
52 /// purpose, so it cannot clash with the name of a user-defined module.
53 pub const METADATA_MODULE_NAME: &'static str = "crate.metadata";
54 /// The name of the crate-metadata object file the compiler generates. Must
55 /// match up with `METADATA_MODULE_NAME`.
56 pub const METADATA_OBJ_NAME: &'static str = "crate.metadata.o";
58 // RLIB LLVM-BYTECODE OBJECT LAYOUT
61 // 0..10 "RUST_OBJECT" encoded in ASCII
62 // 11..14 format version as little-endian u32
63 // 15..22 size in bytes of deflate compressed LLVM bitcode as
65 // 23.. compressed LLVM bitcode
67 // This is the "magic number" expected at the beginning of a LLVM bytecode
69 pub const RLIB_BYTECODE_OBJECT_MAGIC: &'static [u8] = b"RUST_OBJECT";
71 // The version number this compiler will write to bytecode objects in rlibs
72 pub const RLIB_BYTECODE_OBJECT_VERSION: u32 = 1;
74 // The offset in bytes the bytecode object format version number can be found at
75 pub const RLIB_BYTECODE_OBJECT_VERSION_OFFSET: usize = 11;
77 // The offset in bytes the size of the compressed bytecode can be found at in
79 pub const RLIB_BYTECODE_OBJECT_V1_DATASIZE_OFFSET: usize =
80 RLIB_BYTECODE_OBJECT_VERSION_OFFSET + 4;
82 // The offset in bytes the compressed LLVM bytecode can be found at in format
84 pub const RLIB_BYTECODE_OBJECT_V1_DATA_OFFSET: usize =
85 RLIB_BYTECODE_OBJECT_V1_DATASIZE_OFFSET + 8;
88 pub fn find_crate_name(sess: Option<&Session>,
89 attrs: &[ast::Attribute],
90 input: &Input) -> String {
91 let validate = |s: String, span: Option<Span>| {
92 cstore::validate_crate_name(sess, &s, span);
96 // Look in attributes 100% of the time to make sure the attribute is marked
97 // as used. After doing this, however, we still prioritize a crate name from
98 // the command line over one found in the #[crate_name] attribute. If we
99 // find both we ensure that they're the same later on as well.
100 let attr_crate_name = attrs.iter().find(|at| at.check_name("crate_name"))
101 .and_then(|at| at.value_str().map(|s| (at, s)));
103 if let Some(sess) = sess {
104 if let Some(ref s) = sess.opts.crate_name {
105 if let Some((attr, name)) = attr_crate_name {
107 let msg = format!("--crate-name and #[crate_name] are \
108 required to match, but `{}` != `{}`",
110 sess.span_err(attr.span, &msg);
113 return validate(s.clone(), None);
117 if let Some((attr, s)) = attr_crate_name {
118 return validate(s.to_string(), Some(attr.span));
120 if let Input::File(ref path) = *input {
121 if let Some(s) = path.file_stem().and_then(|s| s.to_str()) {
122 if s.starts_with("-") {
123 let msg = format!("crate names cannot start with a `-`, but \
124 `{}` has a leading hyphen", s);
125 if let Some(sess) = sess {
129 return validate(s.replace("-", "_"), None);
134 "rust_out".to_string()
137 pub fn build_link_meta(incremental_hashes_map: &IncrementalHashesMap) -> LinkMeta {
138 let krate_dep_node = &DepNode::new_no_params(DepKind::Krate);
140 crate_hash: Svh::new(incremental_hashes_map[krate_dep_node].to_smaller_hash()),
146 // The third parameter is for env vars, used on windows to set up the
147 // path for MSVC to find its DLLs, and gcc to find its bundled
149 pub fn get_linker(sess: &Session) -> (String, Command, Vec<(OsString, OsString)>) {
150 let envs = vec![("PATH".into(), command_path(sess))];
152 if let Some(ref linker) = sess.opts.cg.linker {
153 (linker.clone(), Command::new(linker), envs)
154 } else if sess.target.target.options.is_like_msvc {
155 let (cmd, envs) = msvc_link_exe_cmd(sess);
156 ("link.exe".to_string(), cmd, envs)
158 let linker = &sess.target.target.options.linker;
159 (linker.clone(), Command::new(&linker), envs)
164 pub fn msvc_link_exe_cmd(sess: &Session) -> (Command, Vec<(OsString, OsString)>) {
165 use gcc::windows_registry;
167 let target = &sess.opts.target_triple;
168 let tool = windows_registry::find_tool(target, "link.exe");
170 if let Some(tool) = tool {
171 let envs = tool.env().to_vec();
172 (tool.to_command(), envs)
174 debug!("Failed to locate linker.");
175 (Command::new("link.exe"), vec![])
180 pub fn msvc_link_exe_cmd(_sess: &Session) -> (Command, Vec<(OsString, OsString)>) {
181 (Command::new("link.exe"), vec![])
184 pub fn get_ar_prog(sess: &Session) -> String {
185 sess.opts.cg.ar.clone().unwrap_or_else(|| {
186 sess.target.target.options.ar.clone()
190 fn command_path(sess: &Session) -> OsString {
191 // The compiler's sysroot often has some bundled tools, so add it to the
192 // PATH for the child.
193 let mut new_path = sess.host_filesearch(PathKind::All)
194 .get_tools_search_paths();
195 if let Some(path) = env::var_os("PATH") {
196 new_path.extend(env::split_paths(&path));
198 env::join_paths(new_path).unwrap()
201 pub fn remove(sess: &Session, path: &Path) {
202 match fs::remove_file(path) {
205 sess.err(&format!("failed to remove {}: {}",
212 /// Perform the linkage portion of the compilation phase. This will generate all
213 /// of the requested outputs for this compilation session.
214 pub fn link_binary(sess: &Session,
215 trans: &CrateTranslation,
216 outputs: &OutputFilenames,
217 crate_name: &str) -> Vec<PathBuf> {
218 let mut out_filenames = Vec::new();
219 for &crate_type in sess.crate_types.borrow().iter() {
220 // Ignore executable crates if we have -Z no-trans, as they will error.
221 if (sess.opts.debugging_opts.no_trans ||
222 !sess.opts.output_types.should_trans()) &&
223 crate_type == config::CrateTypeExecutable {
227 if invalid_output_for_target(sess, crate_type) {
228 bug!("invalid output type `{:?}` for target os `{}`",
229 crate_type, sess.opts.target_triple);
231 let mut out_files = link_binary_output(sess, trans, crate_type, outputs, crate_name);
232 out_filenames.append(&mut out_files);
235 // Remove the temporary object file and metadata if we aren't saving temps
236 if !sess.opts.cg.save_temps {
237 if sess.opts.output_types.should_trans() {
238 for obj in object_filenames(trans, outputs) {
242 remove(sess, &outputs.with_extension(METADATA_OBJ_NAME));
249 /// Returns default crate type for target
251 /// Default crate type is used when crate type isn't provided neither
252 /// through cmd line arguments nor through crate attributes
254 /// It is CrateTypeExecutable for all platforms but iOS as there is no
255 /// way to run iOS binaries anyway without jailbreaking and
256 /// interaction with Rust code through static library is the only
258 pub fn default_output_for_target(sess: &Session) -> config::CrateType {
259 if !sess.target.target.options.executables {
260 config::CrateTypeStaticlib
262 config::CrateTypeExecutable
266 /// Checks if target supports crate_type as output
267 pub fn invalid_output_for_target(sess: &Session,
268 crate_type: config::CrateType) -> bool {
269 match (sess.target.target.options.dynamic_linking,
270 sess.target.target.options.executables, crate_type) {
271 (false, _, config::CrateTypeCdylib) |
272 (false, _, config::CrateTypeProcMacro) |
273 (false, _, config::CrateTypeDylib) => true,
274 (_, false, config::CrateTypeExecutable) => true,
279 fn is_writeable(p: &Path) -> bool {
282 Ok(m) => !m.permissions().readonly()
286 fn filename_for_metadata(sess: &Session, crate_name: &str, outputs: &OutputFilenames) -> PathBuf {
287 let out_filename = outputs.single_output_file.clone()
290 .join(&format!("lib{}{}.rmeta", crate_name, sess.opts.cg.extra_filename)));
291 check_file_is_writeable(&out_filename, sess);
295 pub fn filename_for_input(sess: &Session,
296 crate_type: config::CrateType,
298 outputs: &OutputFilenames) -> PathBuf {
299 let libname = format!("{}{}", crate_name, sess.opts.cg.extra_filename);
302 config::CrateTypeRlib => {
303 outputs.out_directory.join(&format!("lib{}.rlib", libname))
305 config::CrateTypeCdylib |
306 config::CrateTypeProcMacro |
307 config::CrateTypeDylib => {
308 let (prefix, suffix) = (&sess.target.target.options.dll_prefix,
309 &sess.target.target.options.dll_suffix);
310 outputs.out_directory.join(&format!("{}{}{}", prefix, libname,
313 config::CrateTypeStaticlib => {
314 let (prefix, suffix) = (&sess.target.target.options.staticlib_prefix,
315 &sess.target.target.options.staticlib_suffix);
316 outputs.out_directory.join(&format!("{}{}{}", prefix, libname,
319 config::CrateTypeExecutable => {
320 let suffix = &sess.target.target.options.exe_suffix;
321 let out_filename = outputs.path(OutputType::Exe);
322 if suffix.is_empty() {
323 out_filename.to_path_buf()
325 out_filename.with_extension(&suffix[1..])
331 pub fn each_linked_rlib(sess: &Session,
332 f: &mut FnMut(CrateNum, &Path)) -> Result<(), String> {
333 let crates = sess.cstore.used_crates(LinkagePreference::RequireStatic).into_iter();
334 let fmts = sess.dependency_formats.borrow();
335 let fmts = fmts.get(&config::CrateTypeExecutable)
336 .or_else(|| fmts.get(&config::CrateTypeStaticlib))
337 .or_else(|| fmts.get(&config::CrateTypeCdylib))
338 .or_else(|| fmts.get(&config::CrateTypeProcMacro));
339 let fmts = match fmts {
341 None => return Err(format!("could not find formats for rlibs"))
343 for (cnum, path) in crates {
344 match fmts.get(cnum.as_usize() - 1) {
345 Some(&Linkage::NotLinked) |
346 Some(&Linkage::IncludedFromDylib) => continue,
348 None => return Err(format!("could not find formats for rlibs"))
350 let name = sess.cstore.crate_name(cnum).clone();
351 let path = match path {
352 LibSource::Some(p) => p,
353 LibSource::MetadataOnly => {
354 return Err(format!("could not find rlib for: `{}`, found rmeta (metadata) file",
358 return Err(format!("could not find rlib for: `{}`", name))
366 fn out_filename(sess: &Session,
367 crate_type: config::CrateType,
368 outputs: &OutputFilenames,
371 let default_filename = filename_for_input(sess, crate_type, crate_name, outputs);
372 let out_filename = outputs.outputs.get(&OutputType::Exe)
373 .and_then(|s| s.to_owned())
374 .or_else(|| outputs.single_output_file.clone())
375 .unwrap_or(default_filename);
377 check_file_is_writeable(&out_filename, sess);
382 // Make sure files are writeable. Mac, FreeBSD, and Windows system linkers
383 // check this already -- however, the Linux linker will happily overwrite a
384 // read-only file. We should be consistent.
385 fn check_file_is_writeable(file: &Path, sess: &Session) {
386 if !is_writeable(file) {
387 sess.fatal(&format!("output file {} is not writeable -- check its \
388 permissions", file.display()));
392 fn link_binary_output(sess: &Session,
393 trans: &CrateTranslation,
394 crate_type: config::CrateType,
395 outputs: &OutputFilenames,
396 crate_name: &str) -> Vec<PathBuf> {
397 let objects = object_filenames(trans, outputs);
399 for file in &objects {
400 check_file_is_writeable(file, sess);
403 let tmpdir = match TempDir::new("rustc") {
404 Ok(tmpdir) => tmpdir,
405 Err(err) => sess.fatal(&format!("couldn't create a temp dir: {}", err)),
408 let mut out_filenames = vec![];
410 if outputs.outputs.contains_key(&OutputType::Metadata) {
411 let out_filename = filename_for_metadata(sess, crate_name, outputs);
412 emit_metadata(sess, trans, &out_filename);
413 out_filenames.push(out_filename);
416 if outputs.outputs.should_trans() {
417 let out_filename = out_filename(sess, crate_type, outputs, crate_name);
419 config::CrateTypeRlib => {
420 link_rlib(sess, Some(trans), &objects, &out_filename,
421 tmpdir.path()).build();
423 config::CrateTypeStaticlib => {
424 link_staticlib(sess, &objects, &out_filename, tmpdir.path());
427 link_natively(sess, crate_type, &objects, &out_filename, trans,
428 outputs, tmpdir.path());
431 out_filenames.push(out_filename);
434 if sess.opts.cg.save_temps {
435 let _ = tmpdir.into_path();
441 fn object_filenames(trans: &CrateTranslation,
442 outputs: &OutputFilenames)
444 trans.modules.iter().map(|module| {
445 outputs.temp_path(OutputType::Object, Some(&module.name))
449 fn archive_search_paths(sess: &Session) -> Vec<PathBuf> {
450 let mut search = Vec::new();
451 sess.target_filesearch(PathKind::Native).for_each_lib_search_path(|path, _| {
452 search.push(path.to_path_buf());
457 fn archive_config<'a>(sess: &'a Session,
459 input: Option<&Path>) -> ArchiveConfig<'a> {
462 dst: output.to_path_buf(),
463 src: input.map(|p| p.to_path_buf()),
464 lib_search_paths: archive_search_paths(sess),
465 ar_prog: get_ar_prog(sess),
466 command_path: command_path(sess),
470 fn emit_metadata<'a>(sess: &'a Session, trans: &CrateTranslation, out_filename: &Path) {
471 let result = fs::File::create(out_filename).and_then(|mut f| {
472 f.write_all(&trans.metadata.raw_data)
475 if let Err(e) = result {
476 sess.fatal(&format!("failed to write {}: {}", out_filename.display(), e));
482 // An rlib in its current incarnation is essentially a renamed .a file. The
483 // rlib primarily contains the object file of the crate, but it also contains
484 // all of the object files from native libraries. This is done by unzipping
485 // native libraries and inserting all of the contents into this archive.
486 fn link_rlib<'a>(sess: &'a Session,
487 trans: Option<&CrateTranslation>, // None == no metadata/bytecode
490 tmpdir: &Path) -> ArchiveBuilder<'a> {
491 info!("preparing rlib from {:?} to {:?}", objects, out_filename);
492 let mut ab = ArchiveBuilder::new(archive_config(sess, out_filename, None));
498 // Note that in this loop we are ignoring the value of `lib.cfg`. That is,
499 // we may not be configured to actually include a static library if we're
500 // adding it here. That's because later when we consume this rlib we'll
501 // decide whether we actually needed the static library or not.
503 // To do this "correctly" we'd need to keep track of which libraries added
504 // which object files to the archive. We don't do that here, however. The
505 // #[link(cfg(..))] feature is unstable, though, and only intended to get
506 // liblibc working. In that sense the check below just indicates that if
507 // there are any libraries we want to omit object files for at link time we
508 // just exclude all custom object files.
510 // Eventually if we want to stabilize or flesh out the #[link(cfg(..))]
511 // feature then we'll need to figure out how to record what objects were
512 // loaded from the libraries found here and then encode that into the
513 // metadata of the rlib we're generating somehow.
514 for lib in sess.cstore.used_libraries() {
516 NativeLibraryKind::NativeStatic => {}
517 NativeLibraryKind::NativeStaticNobundle |
518 NativeLibraryKind::NativeFramework |
519 NativeLibraryKind::NativeUnknown => continue,
521 ab.add_native_library(&lib.name.as_str());
524 // After adding all files to the archive, we need to update the
525 // symbol table of the archive.
528 // Note that it is important that we add all of our non-object "magical
529 // files" *after* all of the object files in the archive. The reason for
530 // this is as follows:
532 // * When performing LTO, this archive will be modified to remove
533 // objects from above. The reason for this is described below.
535 // * When the system linker looks at an archive, it will attempt to
536 // determine the architecture of the archive in order to see whether its
539 // The algorithm for this detection is: iterate over the files in the
540 // archive. Skip magical SYMDEF names. Interpret the first file as an
541 // object file. Read architecture from the object file.
543 // * As one can probably see, if "metadata" and "foo.bc" were placed
544 // before all of the objects, then the architecture of this archive would
545 // not be correctly inferred once 'foo.o' is removed.
547 // Basically, all this means is that this code should not move above the
551 // Instead of putting the metadata in an object file section, rlibs
552 // contain the metadata in a separate file. We use a temp directory
553 // here so concurrent builds in the same directory don't try to use
554 // the same filename for metadata (stomping over one another)
555 let metadata = tmpdir.join(METADATA_FILENAME);
556 emit_metadata(sess, trans, &metadata);
557 ab.add_file(&metadata);
559 // For LTO purposes, the bytecode of this library is also inserted
560 // into the archive. If codegen_units > 1, we insert each of the
563 // Note that we make sure that the bytecode filename in the
564 // archive is never exactly 16 bytes long by adding a 16 byte
565 // extension to it. This is to work around a bug in LLDB that
566 // would cause it to crash if the name of a file in an archive
567 // was exactly 16 bytes.
568 let bc_filename = obj.with_extension("bc");
569 let bc_deflated_filename = tmpdir.join({
570 obj.with_extension("bytecode.deflate").file_name().unwrap()
573 let mut bc_data = Vec::new();
574 match fs::File::open(&bc_filename).and_then(|mut f| {
575 f.read_to_end(&mut bc_data)
578 Err(e) => sess.fatal(&format!("failed to read bytecode: {}",
582 let mut bc_data_deflated = Vec::new();
583 ZlibEncoder::new(&mut bc_data_deflated, Compression::Default)
584 .write_all(&bc_data).unwrap();
586 let mut bc_file_deflated = match fs::File::create(&bc_deflated_filename) {
589 sess.fatal(&format!("failed to create compressed \
590 bytecode file: {}", e))
594 match write_rlib_bytecode_object_v1(&mut bc_file_deflated,
598 sess.fatal(&format!("failed to write compressed \
603 ab.add_file(&bc_deflated_filename);
605 // See the bottom of back::write::run_passes for an explanation
606 // of when we do and don't keep .#module-name#.bc files around.
607 let user_wants_numbered_bitcode =
608 sess.opts.output_types.contains_key(&OutputType::Bitcode) &&
609 sess.opts.cg.codegen_units > 1;
610 if !sess.opts.cg.save_temps && !user_wants_numbered_bitcode {
611 remove(sess, &bc_filename);
615 // After adding all files to the archive, we need to update the
616 // symbol table of the archive. This currently dies on macOS (see
617 // #11162), and isn't necessary there anyway
618 if !sess.target.target.options.is_like_osx {
629 fn write_rlib_bytecode_object_v1(writer: &mut Write,
630 bc_data_deflated: &[u8]) -> io::Result<()> {
631 let bc_data_deflated_size: u64 = bc_data_deflated.len() as u64;
633 writer.write_all(RLIB_BYTECODE_OBJECT_MAGIC)?;
634 writer.write_all(&[1, 0, 0, 0])?;
636 (bc_data_deflated_size >> 0) as u8,
637 (bc_data_deflated_size >> 8) as u8,
638 (bc_data_deflated_size >> 16) as u8,
639 (bc_data_deflated_size >> 24) as u8,
640 (bc_data_deflated_size >> 32) as u8,
641 (bc_data_deflated_size >> 40) as u8,
642 (bc_data_deflated_size >> 48) as u8,
643 (bc_data_deflated_size >> 56) as u8,
645 writer.write_all(&bc_data_deflated)?;
647 let number_of_bytes_written_so_far =
648 RLIB_BYTECODE_OBJECT_MAGIC.len() + // magic id
649 mem::size_of_val(&RLIB_BYTECODE_OBJECT_VERSION) + // version
650 mem::size_of_val(&bc_data_deflated_size) + // data size field
651 bc_data_deflated_size as usize; // actual data
653 // If the number of bytes written to the object so far is odd, add a
654 // padding byte to make it even. This works around a crash bug in LLDB
655 // (see issue #15950)
656 if number_of_bytes_written_so_far % 2 == 1 {
657 writer.write_all(&[0])?;
663 // Create a static archive
665 // This is essentially the same thing as an rlib, but it also involves adding
666 // all of the upstream crates' objects into the archive. This will slurp in
667 // all of the native libraries of upstream dependencies as well.
669 // Additionally, there's no way for us to link dynamic libraries, so we warn
670 // about all dynamic library dependencies that they're not linked in.
672 // There's no need to include metadata in a static archive, so ensure to not
673 // link in the metadata object file (and also don't prepare the archive with a
675 fn link_staticlib(sess: &Session, objects: &[PathBuf], out_filename: &Path,
677 let mut ab = link_rlib(sess, None, objects, out_filename, tempdir);
678 let mut all_native_libs = vec![];
680 let res = each_linked_rlib(sess, &mut |cnum, path| {
681 let name = sess.cstore.crate_name(cnum);
682 let native_libs = sess.cstore.native_libraries(cnum);
684 // Here when we include the rlib into our staticlib we need to make a
685 // decision whether to include the extra object files along the way.
686 // These extra object files come from statically included native
687 // libraries, but they may be cfg'd away with #[link(cfg(..))].
689 // This unstable feature, though, only needs liblibc to work. The only
690 // use case there is where musl is statically included in liblibc.rlib,
691 // so if we don't want the included version we just need to skip it. As
692 // a result the logic here is that if *any* linked library is cfg'd away
693 // we just skip all object files.
695 // Clearly this is not sufficient for a general purpose feature, and
696 // we'd want to read from the library's metadata to determine which
697 // object files come from where and selectively skip them.
698 let skip_object_files = native_libs.iter().any(|lib| {
699 lib.kind == NativeLibraryKind::NativeStatic && !relevant_lib(sess, lib)
701 ab.add_rlib(path, &name.as_str(), sess.lto(), skip_object_files).unwrap();
703 all_native_libs.extend(sess.cstore.native_libraries(cnum));
705 if let Err(e) = res {
712 if !all_native_libs.is_empty() {
713 sess.note_without_error("link against the following native artifacts when linking against \
714 this static library");
715 sess.note_without_error("the order and any duplication can be significant on some \
716 platforms, and so may need to be preserved");
719 for lib in all_native_libs.iter().filter(|l| relevant_lib(sess, l)) {
720 let name = match lib.kind {
721 NativeLibraryKind::NativeStaticNobundle |
722 NativeLibraryKind::NativeUnknown => "library",
723 NativeLibraryKind::NativeFramework => "framework",
724 // These are included, no need to print them
725 NativeLibraryKind::NativeStatic => continue,
727 sess.note_without_error(&format!("{}: {}", name, lib.name));
731 // Create a dynamic library or executable
733 // This will invoke the system linker/cc to create the resulting file. This
734 // links to all upstream files as well.
735 fn link_natively(sess: &Session,
736 crate_type: config::CrateType,
739 trans: &CrateTranslation,
740 outputs: &OutputFilenames,
742 info!("preparing {:?} from {:?} to {:?}", crate_type, objects, out_filename);
743 let flavor = sess.linker_flavor();
745 // The invocations of cc share some flags across platforms
746 let (pname, mut cmd, envs) = get_linker(sess);
747 // This will set PATH on windows
750 let root = sess.target_filesearch(PathKind::Native).get_lib_path();
751 if let Some(args) = sess.target.target.options.pre_link_args.get(&flavor) {
754 if let Some(ref args) = sess.opts.debugging_opts.pre_link_args {
757 cmd.args(&sess.opts.debugging_opts.pre_link_arg);
759 let pre_link_objects = if crate_type == config::CrateTypeExecutable {
760 &sess.target.target.options.pre_link_objects_exe
762 &sess.target.target.options.pre_link_objects_dll
764 for obj in pre_link_objects {
765 cmd.arg(root.join(obj));
768 if sess.target.target.options.is_like_emscripten {
770 cmd.arg(if sess.panic_strategy() == PanicStrategy::Abort {
771 "DISABLE_EXCEPTION_CATCHING=1"
773 "DISABLE_EXCEPTION_CATCHING=0"
778 let mut linker = trans.linker_info.to_linker(cmd, &sess);
779 link_args(&mut *linker, sess, crate_type, tmpdir,
780 objects, out_filename, outputs, trans);
781 cmd = linker.finalize();
783 if let Some(args) = sess.target.target.options.late_link_args.get(&flavor) {
786 for obj in &sess.target.target.options.post_link_objects {
787 cmd.arg(root.join(obj));
789 if let Some(args) = sess.target.target.options.post_link_args.get(&flavor) {
792 for &(ref k, ref v) in &sess.target.target.options.link_env {
796 if sess.opts.debugging_opts.print_link_args {
797 println!("{:?}", &cmd);
800 // May have not found libraries in the right formats.
801 sess.abort_if_errors();
803 // Invoke the system linker
805 // Note that there's a terribly awful hack that really shouldn't be present
806 // in any compiler. Here an environment variable is supported to
807 // automatically retry the linker invocation if the linker looks like it
810 // Gee that seems odd, normally segfaults are things we want to know about!
811 // Unfortunately though in rust-lang/rust#38878 we're experiencing the
812 // linker segfaulting on Travis quite a bit which is causing quite a bit of
813 // pain to land PRs when they spuriously fail due to a segfault.
815 // The issue #38878 has some more debugging information on it as well, but
816 // this unfortunately looks like it's just a race condition in macOS's linker
817 // with some thread pool working in the background. It seems that no one
818 // currently knows a fix for this so in the meantime we're left with this...
820 let retry_on_segfault = env::var("RUSTC_RETRY_LINKER_ON_SEGFAULT").is_ok();
825 prog = time(sess.time_passes(), "running linker", || cmd.output());
826 if !retry_on_segfault || i > 3 {
829 let output = match prog {
830 Ok(ref output) => output,
833 if output.status.success() {
836 let mut out = output.stderr.clone();
837 out.extend(&output.stdout);
838 let out = String::from_utf8_lossy(&out);
839 let msg = "clang: error: unable to execute command: \
840 Segmentation fault: 11";
841 if !out.contains(msg) {
845 sess.struct_warn("looks like the linker segfaulted when we tried to \
846 call it, automatically retrying again")
847 .note(&format!("{:?}", cmd))
854 fn escape_string(s: &[u8]) -> String {
855 str::from_utf8(s).map(|s| s.to_owned())
856 .unwrap_or_else(|_| {
857 let mut x = "Non-UTF-8 output: ".to_string();
859 .flat_map(|&b| ascii::escape_default(b))
860 .map(|b| char::from_u32(b as u32).unwrap()));
864 if !prog.status.success() {
865 let mut output = prog.stderr.clone();
866 output.extend_from_slice(&prog.stdout);
867 sess.struct_err(&format!("linking with `{}` failed: {}",
870 .note(&format!("{:?}", &cmd))
871 .note(&escape_string(&output))
873 sess.abort_if_errors();
875 info!("linker stderr:\n{}", escape_string(&prog.stderr));
876 info!("linker stdout:\n{}", escape_string(&prog.stdout));
879 sess.struct_err(&format!("could not exec the linker `{}`: {}", pname, e))
880 .note(&format!("{:?}", &cmd))
882 if sess.target.target.options.is_like_msvc && e.kind() == io::ErrorKind::NotFound {
883 sess.note_without_error("the msvc targets depend on the msvc linker \
884 but `link.exe` was not found");
885 sess.note_without_error("please ensure that VS 2013 or VS 2015 was installed \
886 with the Visual C++ option");
888 sess.abort_if_errors();
893 // On macOS, debuggers need this utility to get run to do some munging of
895 if sess.target.target.options.is_like_osx && sess.opts.debuginfo != NoDebugInfo {
896 match Command::new("dsymutil").arg(out_filename).output() {
898 Err(e) => sess.fatal(&format!("failed to run dsymutil: {}", e)),
903 fn link_args(cmd: &mut Linker,
905 crate_type: config::CrateType,
909 outputs: &OutputFilenames,
910 trans: &CrateTranslation) {
912 // The default library location, we need this to find the runtime.
913 // The location of crates will be determined as needed.
914 let lib_path = sess.target_filesearch(PathKind::All).get_lib_path();
917 let t = &sess.target.target;
919 cmd.include_path(&fix_windows_verbatim_for_gcc(&lib_path));
923 cmd.output_filename(out_filename);
925 if crate_type == config::CrateTypeExecutable &&
926 sess.target.target.options.is_like_windows {
927 if let Some(ref s) = trans.windows_subsystem {
932 // If we're building a dynamic library then some platforms need to make sure
933 // that all symbols are exported correctly from the dynamic library.
934 if crate_type != config::CrateTypeExecutable ||
935 sess.target.target.options.is_like_emscripten {
936 cmd.export_symbols(tmpdir, crate_type);
939 // When linking a dynamic library, we put the metadata into a section of the
940 // executable. This metadata is in a separate object file from the main
941 // object file, so we link that in here.
942 if crate_type == config::CrateTypeDylib ||
943 crate_type == config::CrateTypeProcMacro {
944 cmd.add_object(&outputs.with_extension(METADATA_OBJ_NAME));
947 // Try to strip as much out of the generated object by removing unused
948 // sections if possible. See more comments in linker.rs
949 if !sess.opts.cg.link_dead_code {
950 let keep_metadata = crate_type == config::CrateTypeDylib;
951 cmd.gc_sections(keep_metadata);
954 let used_link_args = sess.cstore.used_link_args();
956 if crate_type == config::CrateTypeExecutable &&
957 t.options.position_independent_executables {
958 let empty_vec = Vec::new();
959 let args = sess.opts.cg.link_args.as_ref().unwrap_or(&empty_vec);
960 let more_args = &sess.opts.cg.link_arg;
961 let mut args = args.iter().chain(more_args.iter()).chain(used_link_args.iter());
963 if get_reloc_model(sess) == llvm::RelocMode::PIC
964 && !args.any(|x| *x == "-static") {
965 cmd.position_independent_executable();
969 // Pass optimization flags down to the linker.
972 // Pass debuginfo flags down to the linker.
975 // We want to prevent the compiler from accidentally leaking in any system
976 // libraries, so we explicitly ask gcc to not link to any libraries by
977 // default. Note that this does not happen for windows because windows pulls
978 // in some large number of libraries and I couldn't quite figure out which
980 if t.options.no_default_libraries {
981 cmd.no_default_libraries();
984 // Take careful note of the ordering of the arguments we pass to the linker
985 // here. Linkers will assume that things on the left depend on things to the
986 // right. Things on the right cannot depend on things on the left. This is
987 // all formally implemented in terms of resolving symbols (libs on the right
988 // resolve unknown symbols of libs on the left, but not vice versa).
990 // For this reason, we have organized the arguments we pass to the linker as
993 // 1. The local object that LLVM just generated
994 // 2. Local native libraries
995 // 3. Upstream rust libraries
996 // 4. Upstream native libraries
998 // The rationale behind this ordering is that those items lower down in the
999 // list can't depend on items higher up in the list. For example nothing can
1000 // depend on what we just generated (e.g. that'd be a circular dependency).
1001 // Upstream rust libraries are not allowed to depend on our local native
1002 // libraries as that would violate the structure of the DAG, in that
1003 // scenario they are required to link to them as well in a shared fashion.
1005 // Note that upstream rust libraries may contain native dependencies as
1006 // well, but they also can't depend on what we just started to add to the
1007 // link line. And finally upstream native libraries can't depend on anything
1008 // in this DAG so far because they're only dylibs and dylibs can only depend
1009 // on other dylibs (e.g. other native deps).
1010 add_local_native_libraries(cmd, sess);
1011 add_upstream_rust_crates(cmd, sess, crate_type, tmpdir);
1012 add_upstream_native_libraries(cmd, sess, crate_type);
1014 // # Telling the linker what we're doing
1016 if crate_type != config::CrateTypeExecutable {
1017 cmd.build_dylib(out_filename);
1020 // FIXME (#2397): At some point we want to rpath our guesses as to
1021 // where extern libraries might live, based on the
1022 // addl_lib_search_paths
1023 if sess.opts.cg.rpath {
1024 let sysroot = sess.sysroot();
1025 let target_triple = &sess.opts.target_triple;
1026 let mut get_install_prefix_lib_path = || {
1027 let install_prefix = option_env!("CFG_PREFIX").expect("CFG_PREFIX");
1028 let tlib = filesearch::relative_target_lib_path(sysroot, target_triple);
1029 let mut path = PathBuf::from(install_prefix);
1034 let mut rpath_config = RPathConfig {
1035 used_crates: sess.cstore.used_crates(LinkagePreference::RequireDynamic),
1036 out_filename: out_filename.to_path_buf(),
1037 has_rpath: sess.target.target.options.has_rpath,
1038 is_like_osx: sess.target.target.options.is_like_osx,
1039 linker_is_gnu: sess.target.target.options.linker_is_gnu,
1040 get_install_prefix_lib_path: &mut get_install_prefix_lib_path,
1042 cmd.args(&rpath::get_rpath_flags(&mut rpath_config));
1045 // Finally add all the linker arguments provided on the command line along
1046 // with any #[link_args] attributes found inside the crate
1047 if let Some(ref args) = sess.opts.cg.link_args {
1050 cmd.args(&sess.opts.cg.link_arg);
1051 cmd.args(&used_link_args);
1054 // # Native library linking
1056 // User-supplied library search paths (-L on the command line). These are
1057 // the same paths used to find Rust crates, so some of them may have been
1058 // added already by the previous crate linking code. This only allows them
1059 // to be found at compile time so it is still entirely up to outside
1060 // forces to make sure that library can be found at runtime.
1062 // Also note that the native libraries linked here are only the ones located
1063 // in the current crate. Upstream crates with native library dependencies
1064 // may have their native library pulled in above.
1065 fn add_local_native_libraries(cmd: &mut Linker, sess: &Session) {
1066 sess.target_filesearch(PathKind::All).for_each_lib_search_path(|path, k| {
1068 PathKind::Framework => { cmd.framework_path(path); }
1069 _ => { cmd.include_path(&fix_windows_verbatim_for_gcc(path)); }
1073 let relevant_libs = sess.cstore.used_libraries().into_iter().filter(|l| {
1074 relevant_lib(sess, l)
1077 let search_path = archive_search_paths(sess);
1078 for lib in relevant_libs {
1080 NativeLibraryKind::NativeUnknown => cmd.link_dylib(&lib.name.as_str()),
1081 NativeLibraryKind::NativeFramework => cmd.link_framework(&lib.name.as_str()),
1082 NativeLibraryKind::NativeStaticNobundle => cmd.link_staticlib(&lib.name.as_str()),
1083 NativeLibraryKind::NativeStatic => cmd.link_whole_staticlib(&lib.name.as_str(),
1089 // # Rust Crate linking
1091 // Rust crates are not considered at all when creating an rlib output. All
1092 // dependencies will be linked when producing the final output (instead of
1093 // the intermediate rlib version)
1094 fn add_upstream_rust_crates(cmd: &mut Linker,
1096 crate_type: config::CrateType,
1098 // All of the heavy lifting has previously been accomplished by the
1099 // dependency_format module of the compiler. This is just crawling the
1100 // output of that module, adding crates as necessary.
1102 // Linking to a rlib involves just passing it to the linker (the linker
1103 // will slurp up the object files inside), and linking to a dynamic library
1104 // involves just passing the right -l flag.
1106 let formats = sess.dependency_formats.borrow();
1107 let data = formats.get(&crate_type).unwrap();
1109 // Invoke get_used_crates to ensure that we get a topological sorting of
1111 let deps = sess.cstore.used_crates(LinkagePreference::RequireDynamic);
1113 let mut compiler_builtins = None;
1115 for &(cnum, _) in &deps {
1116 // We may not pass all crates through to the linker. Some crates may
1117 // appear statically in an existing dylib, meaning we'll pick up all the
1118 // symbols from the dylib.
1119 let src = sess.cstore.used_crate_source(cnum);
1120 match data[cnum.as_usize() - 1] {
1121 _ if sess.cstore.is_profiler_runtime(cnum) => {
1122 add_static_crate(cmd, sess, tmpdir, crate_type, cnum);
1124 _ if sess.cstore.is_sanitizer_runtime(cnum) => {
1125 link_sanitizer_runtime(cmd, sess, tmpdir, cnum);
1127 // compiler-builtins are always placed last to ensure that they're
1128 // linked correctly.
1129 _ if sess.cstore.is_compiler_builtins(cnum) => {
1130 assert!(compiler_builtins.is_none());
1131 compiler_builtins = Some(cnum);
1133 Linkage::NotLinked |
1134 Linkage::IncludedFromDylib => {}
1135 Linkage::Static => {
1136 add_static_crate(cmd, sess, tmpdir, crate_type, cnum);
1138 Linkage::Dynamic => {
1139 add_dynamic_crate(cmd, sess, &src.dylib.unwrap().0)
1144 // compiler-builtins are always placed last to ensure that they're
1145 // linked correctly.
1146 // We must always link the `compiler_builtins` crate statically. Even if it
1147 // was already "included" in a dylib (e.g. `libstd` when `-C prefer-dynamic`
1149 if let Some(cnum) = compiler_builtins {
1150 add_static_crate(cmd, sess, tmpdir, crate_type, cnum);
1153 // Converts a library file-stem into a cc -l argument
1154 fn unlib<'a>(config: &config::Config, stem: &'a str) -> &'a str {
1155 if stem.starts_with("lib") && !config.target.options.is_like_windows {
1162 // We must link the sanitizer runtime using -Wl,--whole-archive but since
1163 // it's packed in a .rlib, it contains stuff that are not objects that will
1164 // make the linker error. So we must remove those bits from the .rlib before
1166 fn link_sanitizer_runtime(cmd: &mut Linker,
1170 let src = sess.cstore.used_crate_source(cnum);
1171 let cratepath = &src.rlib.unwrap().0;
1173 if sess.target.target.options.is_like_osx {
1174 // On Apple platforms, the sanitizer is always built as a dylib, and
1175 // LLVM will link to `@rpath/*.dylib`, so we need to specify an
1176 // rpath to the library as well (the rpath should be absolute, see
1177 // PR #41352 for details).
1179 // FIXME: Remove this logic into librustc_*san once Cargo supports it
1180 let rpath = cratepath.parent().unwrap();
1181 let rpath = rpath.to_str().expect("non-utf8 component in path");
1182 cmd.args(&["-Wl,-rpath".into(), "-Xlinker".into(), rpath.into()]);
1185 let dst = tmpdir.join(cratepath.file_name().unwrap());
1186 let cfg = archive_config(sess, &dst, Some(cratepath));
1187 let mut archive = ArchiveBuilder::new(cfg);
1188 archive.update_symbols();
1190 for f in archive.src_files() {
1191 if f.ends_with("bytecode.deflate") || f == METADATA_FILENAME {
1192 archive.remove_file(&f);
1199 cmd.link_whole_rlib(&dst);
1202 // Adds the static "rlib" versions of all crates to the command line.
1203 // There's a bit of magic which happens here specifically related to LTO and
1204 // dynamic libraries. Specifically:
1206 // * For LTO, we remove upstream object files.
1207 // * For dylibs we remove metadata and bytecode from upstream rlibs
1209 // When performing LTO, almost(*) all of the bytecode from the upstream
1210 // libraries has already been included in our object file output. As a
1211 // result we need to remove the object files in the upstream libraries so
1212 // the linker doesn't try to include them twice (or whine about duplicate
1213 // symbols). We must continue to include the rest of the rlib, however, as
1214 // it may contain static native libraries which must be linked in.
1216 // (*) Crates marked with `#![no_builtins]` don't participate in LTO and
1217 // their bytecode wasn't included. The object files in those libraries must
1218 // still be passed to the linker.
1220 // When making a dynamic library, linkers by default don't include any
1221 // object files in an archive if they're not necessary to resolve the link.
1222 // We basically want to convert the archive (rlib) to a dylib, though, so we
1223 // *do* want everything included in the output, regardless of whether the
1224 // linker thinks it's needed or not. As a result we must use the
1225 // --whole-archive option (or the platform equivalent). When using this
1226 // option the linker will fail if there are non-objects in the archive (such
1227 // as our own metadata and/or bytecode). All in all, for rlibs to be
1228 // entirely included in dylibs, we need to remove all non-object files.
1230 // Note, however, that if we're not doing LTO or we're not producing a dylib
1231 // (aka we're making an executable), we can just pass the rlib blindly to
1232 // the linker (fast) because it's fine if it's not actually included as
1233 // we're at the end of the dependency chain.
1234 fn add_static_crate(cmd: &mut Linker,
1237 crate_type: config::CrateType,
1239 let src = sess.cstore.used_crate_source(cnum);
1240 let cratepath = &src.rlib.unwrap().0;
1242 // See the comment above in `link_staticlib` and `link_rlib` for why if
1243 // there's a static library that's not relevant we skip all object
1245 let native_libs = sess.cstore.native_libraries(cnum);
1246 let skip_native = native_libs.iter().any(|lib| {
1247 lib.kind == NativeLibraryKind::NativeStatic && !relevant_lib(sess, lib)
1250 if !sess.lto() && crate_type != config::CrateTypeDylib && !skip_native {
1251 cmd.link_rlib(&fix_windows_verbatim_for_gcc(cratepath));
1255 let dst = tmpdir.join(cratepath.file_name().unwrap());
1256 let name = cratepath.file_name().unwrap().to_str().unwrap();
1257 let name = &name[3..name.len() - 5]; // chop off lib/.rlib
1259 time(sess.time_passes(), &format!("altering {}.rlib", name), || {
1260 let cfg = archive_config(sess, &dst, Some(cratepath));
1261 let mut archive = ArchiveBuilder::new(cfg);
1262 archive.update_symbols();
1264 let mut any_objects = false;
1265 for f in archive.src_files() {
1266 if f.ends_with("bytecode.deflate") || f == METADATA_FILENAME {
1267 archive.remove_file(&f);
1271 let canonical = f.replace("-", "_");
1272 let canonical_name = name.replace("-", "_");
1274 let is_rust_object =
1275 canonical.starts_with(&canonical_name) && {
1276 let num = &f[name.len()..f.len() - 2];
1277 num.len() > 0 && num[1..].parse::<u32>().is_ok()
1280 // If we've been requested to skip all native object files
1281 // (those not generated by the rust compiler) then we can skip
1282 // this file. See above for why we may want to do this.
1283 let skip_because_cfg_say_so = skip_native && !is_rust_object;
1285 // If we're performing LTO and this is a rust-generated object
1286 // file, then we don't need the object file as it's part of the
1287 // LTO module. Note that `#![no_builtins]` is excluded from LTO,
1288 // though, so we let that object file slide.
1289 let skip_because_lto = sess.lto() && is_rust_object &&
1290 !sess.cstore.is_no_builtins(cnum);
1292 if skip_because_cfg_say_so || skip_because_lto {
1293 archive.remove_file(&f);
1304 // If we're creating a dylib, then we need to include the
1305 // whole of each object in our archive into that artifact. This is
1306 // because a `dylib` can be reused as an intermediate artifact.
1308 // Note, though, that we don't want to include the whole of a
1309 // compiler-builtins crate (e.g. compiler-rt) because it'll get
1310 // repeatedly linked anyway.
1311 if crate_type == config::CrateTypeDylib &&
1312 !sess.cstore.is_compiler_builtins(cnum) {
1313 cmd.link_whole_rlib(&fix_windows_verbatim_for_gcc(&dst));
1315 cmd.link_rlib(&fix_windows_verbatim_for_gcc(&dst));
1320 // Same thing as above, but for dynamic crates instead of static crates.
1321 fn add_dynamic_crate(cmd: &mut Linker, sess: &Session, cratepath: &Path) {
1322 // If we're performing LTO, then it should have been previously required
1323 // that all upstream rust dependencies were available in an rlib format.
1324 assert!(!sess.lto());
1326 // Just need to tell the linker about where the library lives and
1328 let parent = cratepath.parent();
1329 if let Some(dir) = parent {
1330 cmd.include_path(&fix_windows_verbatim_for_gcc(dir));
1332 let filestem = cratepath.file_stem().unwrap().to_str().unwrap();
1333 cmd.link_rust_dylib(&unlib(&sess.target, filestem),
1334 parent.unwrap_or(Path::new("")));
1338 // Link in all of our upstream crates' native dependencies. Remember that
1339 // all of these upstream native dependencies are all non-static
1340 // dependencies. We've got two cases then:
1342 // 1. The upstream crate is an rlib. In this case we *must* link in the
1343 // native dependency because the rlib is just an archive.
1345 // 2. The upstream crate is a dylib. In order to use the dylib, we have to
1346 // have the dependency present on the system somewhere. Thus, we don't
1347 // gain a whole lot from not linking in the dynamic dependency to this
1350 // The use case for this is a little subtle. In theory the native
1351 // dependencies of a crate are purely an implementation detail of the crate
1352 // itself, but the problem arises with generic and inlined functions. If a
1353 // generic function calls a native function, then the generic function must
1354 // be instantiated in the target crate, meaning that the native symbol must
1355 // also be resolved in the target crate.
1356 fn add_upstream_native_libraries(cmd: &mut Linker, sess: &Session, crate_type: config::CrateType) {
1357 // Be sure to use a topological sorting of crates because there may be
1358 // interdependencies between native libraries. When passing -nodefaultlibs,
1359 // for example, almost all native libraries depend on libc, so we have to
1360 // make sure that's all the way at the right (liblibc is near the base of
1361 // the dependency chain).
1363 // This passes RequireStatic, but the actual requirement doesn't matter,
1364 // we're just getting an ordering of crate numbers, we're not worried about
1366 let formats = sess.dependency_formats.borrow();
1367 let data = formats.get(&crate_type).unwrap();
1369 let crates = sess.cstore.used_crates(LinkagePreference::RequireStatic);
1370 for (cnum, _) in crates {
1371 for lib in sess.cstore.native_libraries(cnum) {
1372 if !relevant_lib(sess, &lib) {
1376 NativeLibraryKind::NativeUnknown => cmd.link_dylib(&lib.name.as_str()),
1377 NativeLibraryKind::NativeFramework => cmd.link_framework(&lib.name.as_str()),
1378 NativeLibraryKind::NativeStaticNobundle => {
1379 // Link "static-nobundle" native libs only if the crate they originate from
1380 // is being linked statically to the current crate. If it's linked dynamically
1381 // or is an rlib already included via some other dylib crate, the symbols from
1382 // native libs will have already been included in that dylib.
1383 if data[cnum.as_usize() - 1] == Linkage::Static {
1384 cmd.link_staticlib(&lib.name.as_str())
1387 // ignore statically included native libraries here as we've
1388 // already included them when we included the rust library
1390 NativeLibraryKind::NativeStatic => {}
1396 fn relevant_lib(sess: &Session, lib: &NativeLibrary) -> bool {
1398 Some(ref cfg) => attr::cfg_matches(cfg, &sess.parse_sess, None),