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;
16 use metadata::METADATA_FILENAME;
18 use session::config::NoDebugInfo;
19 use session::config::{OutputFilenames, Input, OutputType};
20 use session::filesearch;
21 use session::search_paths::PathKind;
23 use middle::cstore::{self, LinkMeta, NativeLibrary, LibSource};
24 use middle::cstore::{LinkagePreference, NativeLibraryKind};
25 use middle::dependency_format::Linkage;
27 use util::common::time;
28 use util::fs::fix_windows_verbatim_for_gcc;
29 use rustc::dep_graph::DepNode;
30 use rustc::hir::def_id::CrateNum;
31 use rustc::hir::svh::Svh;
32 use rustc_back::tempdir::TempDir;
33 use rustc_back::PanicStrategy;
34 use rustc_incremental::IncrementalHashesMap;
35 use context::get_reloc_model;
41 use std::ffi::OsString;
43 use std::io::{self, Read, Write};
45 use std::path::{Path, PathBuf};
46 use std::process::Command;
53 /// The LLVM module name containing crate-metadata. This includes a `.` on
54 /// purpose, so it cannot clash with the name of a user-defined module.
55 pub const METADATA_MODULE_NAME: &'static str = "crate.metadata";
56 /// The name of the crate-metadata object file the compiler generates. Must
57 /// match up with `METADATA_MODULE_NAME`.
58 pub const METADATA_OBJ_NAME: &'static str = "crate.metadata.o";
60 // RLIB LLVM-BYTECODE OBJECT LAYOUT
63 // 0..10 "RUST_OBJECT" encoded in ASCII
64 // 11..14 format version as little-endian u32
65 // 15..22 size in bytes of deflate compressed LLVM bitcode as
67 // 23.. compressed LLVM bitcode
69 // This is the "magic number" expected at the beginning of a LLVM bytecode
71 pub const RLIB_BYTECODE_OBJECT_MAGIC: &'static [u8] = b"RUST_OBJECT";
73 // The version number this compiler will write to bytecode objects in rlibs
74 pub const RLIB_BYTECODE_OBJECT_VERSION: u32 = 1;
76 // The offset in bytes the bytecode object format version number can be found at
77 pub const RLIB_BYTECODE_OBJECT_VERSION_OFFSET: usize = 11;
79 // The offset in bytes the size of the compressed bytecode can be found at in
81 pub const RLIB_BYTECODE_OBJECT_V1_DATASIZE_OFFSET: usize =
82 RLIB_BYTECODE_OBJECT_VERSION_OFFSET + 4;
84 // The offset in bytes the compressed LLVM bytecode can be found at in format
86 pub const RLIB_BYTECODE_OBJECT_V1_DATA_OFFSET: usize =
87 RLIB_BYTECODE_OBJECT_V1_DATASIZE_OFFSET + 8;
90 pub fn find_crate_name(sess: Option<&Session>,
91 attrs: &[ast::Attribute],
92 input: &Input) -> String {
93 let validate = |s: String, span: Option<Span>| {
94 cstore::validate_crate_name(sess, &s, span);
98 // Look in attributes 100% of the time to make sure the attribute is marked
99 // as used. After doing this, however, we still prioritize a crate name from
100 // the command line over one found in the #[crate_name] attribute. If we
101 // find both we ensure that they're the same later on as well.
102 let attr_crate_name = attrs.iter().find(|at| at.check_name("crate_name"))
103 .and_then(|at| at.value_str().map(|s| (at, s)));
105 if let Some(sess) = sess {
106 if let Some(ref s) = sess.opts.crate_name {
107 if let Some((attr, name)) = attr_crate_name {
109 let msg = format!("--crate-name and #[crate_name] are \
110 required to match, but `{}` != `{}`",
112 sess.span_err(attr.span, &msg);
115 return validate(s.clone(), None);
119 if let Some((attr, s)) = attr_crate_name {
120 return validate(s.to_string(), Some(attr.span));
122 if let Input::File(ref path) = *input {
123 if let Some(s) = path.file_stem().and_then(|s| s.to_str()) {
124 if s.starts_with("-") {
125 let msg = format!("crate names cannot start with a `-`, but \
126 `{}` has a leading hyphen", s);
127 if let Some(sess) = sess {
131 return validate(s.replace("-", "_"), None);
136 "rust_out".to_string()
139 pub fn build_link_meta(incremental_hashes_map: &IncrementalHashesMap) -> LinkMeta {
141 crate_hash: Svh::new(incremental_hashes_map[&DepNode::Krate].to_smaller_hash()),
147 // The third parameter is for an extra path to add to PATH for MSVC
148 // cross linkers for host toolchain DLL dependencies
149 pub fn get_linker(sess: &Session) -> (String, Command, Option<PathBuf>) {
150 if let Some(ref linker) = sess.opts.cg.linker {
151 (linker.clone(), Command::new(linker), None)
152 } else if sess.target.target.options.is_like_msvc {
153 let (cmd, host) = msvc::link_exe_cmd(sess);
154 ("link.exe".to_string(), cmd, host)
156 (sess.target.target.options.linker.clone(),
157 Command::new(&sess.target.target.options.linker), None)
161 pub fn get_ar_prog(sess: &Session) -> String {
162 sess.opts.cg.ar.clone().unwrap_or_else(|| {
163 sess.target.target.options.ar.clone()
167 fn command_path(sess: &Session, extra: Option<PathBuf>) -> OsString {
168 // The compiler's sysroot often has some bundled tools, so add it to the
169 // PATH for the child.
170 let mut new_path = sess.host_filesearch(PathKind::All)
171 .get_tools_search_paths();
172 if let Some(path) = env::var_os("PATH") {
173 new_path.extend(env::split_paths(&path));
175 new_path.extend(extra);
176 env::join_paths(new_path).unwrap()
179 pub fn remove(sess: &Session, path: &Path) {
180 match fs::remove_file(path) {
183 sess.err(&format!("failed to remove {}: {}",
190 /// Perform the linkage portion of the compilation phase. This will generate all
191 /// of the requested outputs for this compilation session.
192 pub fn link_binary(sess: &Session,
193 trans: &CrateTranslation,
194 outputs: &OutputFilenames,
195 crate_name: &str) -> Vec<PathBuf> {
196 let mut out_filenames = Vec::new();
197 for &crate_type in sess.crate_types.borrow().iter() {
198 // Ignore executable crates if we have -Z no-trans, as they will error.
199 if (sess.opts.debugging_opts.no_trans ||
200 !sess.opts.output_types.should_trans()) &&
201 crate_type == config::CrateTypeExecutable {
205 if invalid_output_for_target(sess, crate_type) {
206 bug!("invalid output type `{:?}` for target os `{}`",
207 crate_type, sess.opts.target_triple);
209 let mut out_files = link_binary_output(sess, trans, crate_type, outputs, crate_name);
210 out_filenames.append(&mut out_files);
213 // Remove the temporary object file and metadata if we aren't saving temps
214 if !sess.opts.cg.save_temps {
215 if sess.opts.output_types.should_trans() {
216 for obj in object_filenames(trans, outputs) {
220 remove(sess, &outputs.with_extension(METADATA_OBJ_NAME));
227 /// Returns default crate type for target
229 /// Default crate type is used when crate type isn't provided neither
230 /// through cmd line arguments nor through crate attributes
232 /// It is CrateTypeExecutable for all platforms but iOS as there is no
233 /// way to run iOS binaries anyway without jailbreaking and
234 /// interaction with Rust code through static library is the only
236 pub fn default_output_for_target(sess: &Session) -> config::CrateType {
237 if !sess.target.target.options.executables {
238 config::CrateTypeStaticlib
240 config::CrateTypeExecutable
244 /// Checks if target supports crate_type as output
245 pub fn invalid_output_for_target(sess: &Session,
246 crate_type: config::CrateType) -> bool {
247 match (sess.target.target.options.dynamic_linking,
248 sess.target.target.options.executables, crate_type) {
249 (false, _, config::CrateTypeCdylib) |
250 (false, _, config::CrateTypeProcMacro) |
251 (false, _, config::CrateTypeDylib) => true,
252 (_, false, config::CrateTypeExecutable) => true,
257 fn is_writeable(p: &Path) -> bool {
260 Ok(m) => !m.permissions().readonly()
264 fn filename_for_metadata(sess: &Session, crate_name: &str, outputs: &OutputFilenames) -> PathBuf {
265 let out_filename = outputs.single_output_file.clone()
268 .join(&format!("lib{}{}.rmeta", crate_name, sess.opts.cg.extra_filename)));
269 check_file_is_writeable(&out_filename, sess);
273 pub fn filename_for_input(sess: &Session,
274 crate_type: config::CrateType,
276 outputs: &OutputFilenames) -> PathBuf {
277 let libname = format!("{}{}", crate_name, sess.opts.cg.extra_filename);
280 config::CrateTypeRlib => {
281 outputs.out_directory.join(&format!("lib{}.rlib", libname))
283 config::CrateTypeCdylib |
284 config::CrateTypeProcMacro |
285 config::CrateTypeDylib => {
286 let (prefix, suffix) = (&sess.target.target.options.dll_prefix,
287 &sess.target.target.options.dll_suffix);
288 outputs.out_directory.join(&format!("{}{}{}", prefix, libname,
291 config::CrateTypeStaticlib => {
292 let (prefix, suffix) = (&sess.target.target.options.staticlib_prefix,
293 &sess.target.target.options.staticlib_suffix);
294 outputs.out_directory.join(&format!("{}{}{}", prefix, libname,
297 config::CrateTypeExecutable => {
298 let suffix = &sess.target.target.options.exe_suffix;
299 let out_filename = outputs.path(OutputType::Exe);
300 if suffix.is_empty() {
301 out_filename.to_path_buf()
303 out_filename.with_extension(&suffix[1..])
309 pub fn each_linked_rlib(sess: &Session,
310 f: &mut FnMut(CrateNum, &Path)) {
311 let crates = sess.cstore.used_crates(LinkagePreference::RequireStatic).into_iter();
312 let fmts = sess.dependency_formats.borrow();
313 let fmts = fmts.get(&config::CrateTypeExecutable)
314 .or_else(|| fmts.get(&config::CrateTypeStaticlib))
315 .or_else(|| fmts.get(&config::CrateTypeCdylib))
316 .or_else(|| fmts.get(&config::CrateTypeProcMacro));
317 let fmts = fmts.unwrap_or_else(|| {
318 bug!("could not find formats for rlibs");
320 for (cnum, path) in crates {
321 match fmts[cnum.as_usize() - 1] {
322 Linkage::NotLinked | Linkage::IncludedFromDylib => continue,
325 let name = sess.cstore.crate_name(cnum).clone();
326 let path = match path {
327 LibSource::Some(p) => p,
328 LibSource::MetadataOnly => {
329 sess.fatal(&format!("could not find rlib for: `{}`, found rmeta (metadata) file",
333 sess.fatal(&format!("could not find rlib for: `{}`", name));
340 fn out_filename(sess: &Session,
341 crate_type: config::CrateType,
342 outputs: &OutputFilenames,
345 let default_filename = filename_for_input(sess, crate_type, crate_name, outputs);
346 let out_filename = outputs.outputs.get(&OutputType::Exe)
347 .and_then(|s| s.to_owned())
348 .or_else(|| outputs.single_output_file.clone())
349 .unwrap_or(default_filename);
351 check_file_is_writeable(&out_filename, sess);
356 // Make sure files are writeable. Mac, FreeBSD, and Windows system linkers
357 // check this already -- however, the Linux linker will happily overwrite a
358 // read-only file. We should be consistent.
359 fn check_file_is_writeable(file: &Path, sess: &Session) {
360 if !is_writeable(file) {
361 sess.fatal(&format!("output file {} is not writeable -- check its \
362 permissions", file.display()));
366 fn link_binary_output(sess: &Session,
367 trans: &CrateTranslation,
368 crate_type: config::CrateType,
369 outputs: &OutputFilenames,
370 crate_name: &str) -> Vec<PathBuf> {
371 let objects = object_filenames(trans, outputs);
373 for file in &objects {
374 check_file_is_writeable(file, sess);
377 let tmpdir = match TempDir::new("rustc") {
378 Ok(tmpdir) => tmpdir,
379 Err(err) => sess.fatal(&format!("couldn't create a temp dir: {}", err)),
382 let mut out_filenames = vec![];
384 if outputs.outputs.contains_key(&OutputType::Metadata) {
385 let out_filename = filename_for_metadata(sess, crate_name, outputs);
386 emit_metadata(sess, trans, &out_filename);
387 out_filenames.push(out_filename);
390 if outputs.outputs.should_trans() {
391 let out_filename = out_filename(sess, crate_type, outputs, crate_name);
393 config::CrateTypeRlib => {
394 link_rlib(sess, Some(trans), &objects, &out_filename,
395 tmpdir.path()).build();
397 config::CrateTypeStaticlib => {
398 link_staticlib(sess, &objects, &out_filename, tmpdir.path());
401 link_natively(sess, crate_type, &objects, &out_filename, trans,
402 outputs, tmpdir.path());
405 out_filenames.push(out_filename);
411 fn object_filenames(trans: &CrateTranslation,
412 outputs: &OutputFilenames)
414 trans.modules.iter().map(|module| {
415 outputs.temp_path(OutputType::Object, Some(&module.name))
419 fn archive_search_paths(sess: &Session) -> Vec<PathBuf> {
420 let mut search = Vec::new();
421 sess.target_filesearch(PathKind::Native).for_each_lib_search_path(|path, _| {
422 search.push(path.to_path_buf());
427 fn archive_config<'a>(sess: &'a Session,
429 input: Option<&Path>) -> ArchiveConfig<'a> {
432 dst: output.to_path_buf(),
433 src: input.map(|p| p.to_path_buf()),
434 lib_search_paths: archive_search_paths(sess),
435 ar_prog: get_ar_prog(sess),
436 command_path: command_path(sess, None),
440 fn emit_metadata<'a>(sess: &'a Session, trans: &CrateTranslation, out_filename: &Path) {
441 let result = fs::File::create(out_filename).and_then(|mut f| {
442 f.write_all(&trans.metadata.raw_data)
445 if let Err(e) = result {
446 sess.fatal(&format!("failed to write {}: {}", out_filename.display(), e));
452 // An rlib in its current incarnation is essentially a renamed .a file. The
453 // rlib primarily contains the object file of the crate, but it also contains
454 // all of the object files from native libraries. This is done by unzipping
455 // native libraries and inserting all of the contents into this archive.
456 fn link_rlib<'a>(sess: &'a Session,
457 trans: Option<&CrateTranslation>, // None == no metadata/bytecode
460 tmpdir: &Path) -> ArchiveBuilder<'a> {
461 info!("preparing rlib from {:?} to {:?}", objects, out_filename);
462 let mut ab = ArchiveBuilder::new(archive_config(sess, out_filename, None));
468 // Note that in this loop we are ignoring the value of `lib.cfg`. That is,
469 // we may not be configured to actually include a static library if we're
470 // adding it here. That's because later when we consume this rlib we'll
471 // decide whether we actually needed the static library or not.
473 // To do this "correctly" we'd need to keep track of which libraries added
474 // which object files to the archive. We don't do that here, however. The
475 // #[link(cfg(..))] feature is unstable, though, and only intended to get
476 // liblibc working. In that sense the check below just indicates that if
477 // there are any libraries we want to omit object files for at link time we
478 // just exclude all custom object files.
480 // Eventually if we want to stabilize or flesh out the #[link(cfg(..))]
481 // feature then we'll need to figure out how to record what objects were
482 // loaded from the libraries found here and then encode that into the
483 // metadata of the rlib we're generating somehow.
484 for lib in sess.cstore.used_libraries() {
486 NativeLibraryKind::NativeStatic => {}
487 NativeLibraryKind::NativeStaticNobundle |
488 NativeLibraryKind::NativeFramework |
489 NativeLibraryKind::NativeUnknown => continue,
491 ab.add_native_library(&lib.name.as_str());
494 // After adding all files to the archive, we need to update the
495 // symbol table of the archive.
498 // Note that it is important that we add all of our non-object "magical
499 // files" *after* all of the object files in the archive. The reason for
500 // this is as follows:
502 // * When performing LTO, this archive will be modified to remove
503 // objects from above. The reason for this is described below.
505 // * When the system linker looks at an archive, it will attempt to
506 // determine the architecture of the archive in order to see whether its
509 // The algorithm for this detection is: iterate over the files in the
510 // archive. Skip magical SYMDEF names. Interpret the first file as an
511 // object file. Read architecture from the object file.
513 // * As one can probably see, if "metadata" and "foo.bc" were placed
514 // before all of the objects, then the architecture of this archive would
515 // not be correctly inferred once 'foo.o' is removed.
517 // Basically, all this means is that this code should not move above the
521 // Instead of putting the metadata in an object file section, rlibs
522 // contain the metadata in a separate file. We use a temp directory
523 // here so concurrent builds in the same directory don't try to use
524 // the same filename for metadata (stomping over one another)
525 let metadata = tmpdir.join(METADATA_FILENAME);
526 emit_metadata(sess, trans, &metadata);
527 ab.add_file(&metadata);
529 // For LTO purposes, the bytecode of this library is also inserted
530 // into the archive. If codegen_units > 1, we insert each of the
533 // Note that we make sure that the bytecode filename in the
534 // archive is never exactly 16 bytes long by adding a 16 byte
535 // extension to it. This is to work around a bug in LLDB that
536 // would cause it to crash if the name of a file in an archive
537 // was exactly 16 bytes.
538 let bc_filename = obj.with_extension("bc");
539 let bc_deflated_filename = tmpdir.join({
540 obj.with_extension("bytecode.deflate").file_name().unwrap()
543 let mut bc_data = Vec::new();
544 match fs::File::open(&bc_filename).and_then(|mut f| {
545 f.read_to_end(&mut bc_data)
548 Err(e) => sess.fatal(&format!("failed to read bytecode: {}",
552 let bc_data_deflated = flate::deflate_bytes(&bc_data);
554 let mut bc_file_deflated = match fs::File::create(&bc_deflated_filename) {
557 sess.fatal(&format!("failed to create compressed \
558 bytecode file: {}", e))
562 match write_rlib_bytecode_object_v1(&mut bc_file_deflated,
566 sess.fatal(&format!("failed to write compressed \
571 ab.add_file(&bc_deflated_filename);
573 // See the bottom of back::write::run_passes for an explanation
574 // of when we do and don't keep .#module-name#.bc files around.
575 let user_wants_numbered_bitcode =
576 sess.opts.output_types.contains_key(&OutputType::Bitcode) &&
577 sess.opts.cg.codegen_units > 1;
578 if !sess.opts.cg.save_temps && !user_wants_numbered_bitcode {
579 remove(sess, &bc_filename);
583 // After adding all files to the archive, we need to update the
584 // symbol table of the archive. This currently dies on macOS (see
585 // #11162), and isn't necessary there anyway
586 if !sess.target.target.options.is_like_osx {
597 fn write_rlib_bytecode_object_v1(writer: &mut Write,
598 bc_data_deflated: &[u8]) -> io::Result<()> {
599 let bc_data_deflated_size: u64 = bc_data_deflated.len() as u64;
601 writer.write_all(RLIB_BYTECODE_OBJECT_MAGIC)?;
602 writer.write_all(&[1, 0, 0, 0])?;
604 (bc_data_deflated_size >> 0) as u8,
605 (bc_data_deflated_size >> 8) as u8,
606 (bc_data_deflated_size >> 16) as u8,
607 (bc_data_deflated_size >> 24) as u8,
608 (bc_data_deflated_size >> 32) as u8,
609 (bc_data_deflated_size >> 40) as u8,
610 (bc_data_deflated_size >> 48) as u8,
611 (bc_data_deflated_size >> 56) as u8,
613 writer.write_all(&bc_data_deflated)?;
615 let number_of_bytes_written_so_far =
616 RLIB_BYTECODE_OBJECT_MAGIC.len() + // magic id
617 mem::size_of_val(&RLIB_BYTECODE_OBJECT_VERSION) + // version
618 mem::size_of_val(&bc_data_deflated_size) + // data size field
619 bc_data_deflated_size as usize; // actual data
621 // If the number of bytes written to the object so far is odd, add a
622 // padding byte to make it even. This works around a crash bug in LLDB
623 // (see issue #15950)
624 if number_of_bytes_written_so_far % 2 == 1 {
625 writer.write_all(&[0])?;
631 // Create a static archive
633 // This is essentially the same thing as an rlib, but it also involves adding
634 // all of the upstream crates' objects into the archive. This will slurp in
635 // all of the native libraries of upstream dependencies as well.
637 // Additionally, there's no way for us to link dynamic libraries, so we warn
638 // about all dynamic library dependencies that they're not linked in.
640 // There's no need to include metadata in a static archive, so ensure to not
641 // link in the metadata object file (and also don't prepare the archive with a
643 fn link_staticlib(sess: &Session, objects: &[PathBuf], out_filename: &Path,
645 let mut ab = link_rlib(sess, None, objects, out_filename, tempdir);
646 let mut all_native_libs = vec![];
648 each_linked_rlib(sess, &mut |cnum, path| {
649 let name = sess.cstore.crate_name(cnum);
650 let native_libs = sess.cstore.native_libraries(cnum);
652 // Here when we include the rlib into our staticlib we need to make a
653 // decision whether to include the extra object files along the way.
654 // These extra object files come from statically included native
655 // libraries, but they may be cfg'd away with #[link(cfg(..))].
657 // This unstable feature, though, only needs liblibc to work. The only
658 // use case there is where musl is statically included in liblibc.rlib,
659 // so if we don't want the included version we just need to skip it. As
660 // a result the logic here is that if *any* linked library is cfg'd away
661 // we just skip all object files.
663 // Clearly this is not sufficient for a general purpose feature, and
664 // we'd want to read from the library's metadata to determine which
665 // object files come from where and selectively skip them.
666 let skip_object_files = native_libs.iter().any(|lib| {
667 lib.kind == NativeLibraryKind::NativeStatic && !relevant_lib(sess, lib)
669 ab.add_rlib(path, &name.as_str(), sess.lto(), skip_object_files).unwrap();
671 all_native_libs.extend(sess.cstore.native_libraries(cnum));
677 if !all_native_libs.is_empty() {
678 sess.note_without_error("link against the following native artifacts when linking against \
679 this static library");
680 sess.note_without_error("the order and any duplication can be significant on some \
681 platforms, and so may need to be preserved");
684 for lib in all_native_libs.iter().filter(|l| relevant_lib(sess, l)) {
685 let name = match lib.kind {
686 NativeLibraryKind::NativeStaticNobundle |
687 NativeLibraryKind::NativeUnknown => "library",
688 NativeLibraryKind::NativeFramework => "framework",
689 // These are included, no need to print them
690 NativeLibraryKind::NativeStatic => continue,
692 sess.note_without_error(&format!("{}: {}", name, lib.name));
696 // Create a dynamic library or executable
698 // This will invoke the system linker/cc to create the resulting file. This
699 // links to all upstream files as well.
700 fn link_natively(sess: &Session,
701 crate_type: config::CrateType,
704 trans: &CrateTranslation,
705 outputs: &OutputFilenames,
707 info!("preparing {:?} from {:?} to {:?}", crate_type, objects, out_filename);
708 let flavor = sess.linker_flavor();
710 // The invocations of cc share some flags across platforms
711 let (pname, mut cmd, extra) = get_linker(sess);
712 cmd.env("PATH", command_path(sess, extra));
714 let root = sess.target_filesearch(PathKind::Native).get_lib_path();
715 if let Some(args) = sess.target.target.options.pre_link_args.get(&flavor) {
719 let pre_link_objects = if crate_type == config::CrateTypeExecutable {
720 &sess.target.target.options.pre_link_objects_exe
722 &sess.target.target.options.pre_link_objects_dll
724 for obj in pre_link_objects {
725 cmd.arg(root.join(obj));
728 if sess.target.target.options.is_like_emscripten {
730 cmd.arg(if sess.panic_strategy() == PanicStrategy::Abort {
731 "DISABLE_EXCEPTION_CATCHING=1"
733 "DISABLE_EXCEPTION_CATCHING=0"
738 let mut linker = trans.linker_info.to_linker(cmd, &sess);
739 link_args(&mut *linker, sess, crate_type, tmpdir,
740 objects, out_filename, outputs, trans);
741 cmd = linker.finalize();
743 if let Some(args) = sess.target.target.options.late_link_args.get(&flavor) {
746 for obj in &sess.target.target.options.post_link_objects {
747 cmd.arg(root.join(obj));
749 if let Some(args) = sess.target.target.options.post_link_args.get(&flavor) {
753 if sess.opts.debugging_opts.print_link_args {
754 println!("{:?}", &cmd);
757 // May have not found libraries in the right formats.
758 sess.abort_if_errors();
760 // Invoke the system linker
762 // Note that there's a terribly awful hack that really shouldn't be present
763 // in any compiler. Here an environment variable is supported to
764 // automatically retry the linker invocation if the linker looks like it
767 // Gee that seems odd, normally segfaults are things we want to know about!
768 // Unfortunately though in rust-lang/rust#38878 we're experiencing the
769 // linker segfaulting on Travis quite a bit which is causing quite a bit of
770 // pain to land PRs when they spuriously fail due to a segfault.
772 // The issue #38878 has some more debugging information on it as well, but
773 // this unfortunately looks like it's just a race condition in macOS's linker
774 // with some thread pool working in the background. It seems that no one
775 // currently knows a fix for this so in the meantime we're left with this...
777 let retry_on_segfault = env::var("RUSTC_RETRY_LINKER_ON_SEGFAULT").is_ok();
782 prog = time(sess.time_passes(), "running linker", || cmd.output());
783 if !retry_on_segfault || i > 3 {
786 let output = match prog {
787 Ok(ref output) => output,
790 if output.status.success() {
793 let mut out = output.stderr.clone();
794 out.extend(&output.stdout);
795 let out = String::from_utf8_lossy(&out);
796 let msg = "clang: error: unable to execute command: \
797 Segmentation fault: 11";
798 if !out.contains(msg) {
802 sess.struct_warn("looks like the linker segfaulted when we tried to \
803 call it, automatically retrying again")
804 .note(&format!("{:?}", cmd))
811 fn escape_string(s: &[u8]) -> String {
812 str::from_utf8(s).map(|s| s.to_owned())
813 .unwrap_or_else(|_| {
814 let mut x = "Non-UTF-8 output: ".to_string();
816 .flat_map(|&b| ascii::escape_default(b))
817 .map(|b| char::from_u32(b as u32).unwrap()));
821 if !prog.status.success() {
822 let mut output = prog.stderr.clone();
823 output.extend_from_slice(&prog.stdout);
824 sess.struct_err(&format!("linking with `{}` failed: {}",
827 .note(&format!("{:?}", &cmd))
828 .note(&escape_string(&output))
830 sess.abort_if_errors();
832 info!("linker stderr:\n{}", escape_string(&prog.stderr));
833 info!("linker stdout:\n{}", escape_string(&prog.stdout));
836 sess.struct_err(&format!("could not exec the linker `{}`: {}", pname, e))
837 .note(&format!("{:?}", &cmd))
839 if sess.target.target.options.is_like_msvc && e.kind() == io::ErrorKind::NotFound {
840 sess.note_without_error("the msvc targets depend on the msvc linker \
841 but `link.exe` was not found");
842 sess.note_without_error("please ensure that VS 2013 or VS 2015 was installed \
843 with the Visual C++ option");
845 sess.abort_if_errors();
850 // On macOS, debuggers need this utility to get run to do some munging of
852 if sess.target.target.options.is_like_osx && sess.opts.debuginfo != NoDebugInfo {
853 match Command::new("dsymutil").arg(out_filename).output() {
855 Err(e) => sess.fatal(&format!("failed to run dsymutil: {}", e)),
860 fn link_args(cmd: &mut Linker,
862 crate_type: config::CrateType,
866 outputs: &OutputFilenames,
867 trans: &CrateTranslation) {
869 // The default library location, we need this to find the runtime.
870 // The location of crates will be determined as needed.
871 let lib_path = sess.target_filesearch(PathKind::All).get_lib_path();
874 let t = &sess.target.target;
876 cmd.include_path(&fix_windows_verbatim_for_gcc(&lib_path));
880 cmd.output_filename(out_filename);
882 if crate_type == config::CrateTypeExecutable &&
883 sess.target.target.options.is_like_windows {
884 if let Some(ref s) = trans.windows_subsystem {
889 // If we're building a dynamic library then some platforms need to make sure
890 // that all symbols are exported correctly from the dynamic library.
891 if crate_type != config::CrateTypeExecutable ||
892 sess.target.target.options.is_like_emscripten {
893 cmd.export_symbols(tmpdir, crate_type);
896 // When linking a dynamic library, we put the metadata into a section of the
897 // executable. This metadata is in a separate object file from the main
898 // object file, so we link that in here.
899 if crate_type == config::CrateTypeDylib ||
900 crate_type == config::CrateTypeProcMacro {
901 cmd.add_object(&outputs.with_extension(METADATA_OBJ_NAME));
904 // Try to strip as much out of the generated object by removing unused
905 // sections if possible. See more comments in linker.rs
906 if !sess.opts.cg.link_dead_code {
907 let keep_metadata = crate_type == config::CrateTypeDylib;
908 cmd.gc_sections(keep_metadata);
911 let used_link_args = sess.cstore.used_link_args();
913 if crate_type == config::CrateTypeExecutable &&
914 t.options.position_independent_executables {
915 let empty_vec = Vec::new();
916 let args = sess.opts.cg.link_args.as_ref().unwrap_or(&empty_vec);
917 let more_args = &sess.opts.cg.link_arg;
918 let mut args = args.iter().chain(more_args.iter()).chain(used_link_args.iter());
920 if get_reloc_model(sess) == llvm::RelocMode::PIC
921 && !args.any(|x| *x == "-static") {
922 cmd.position_independent_executable();
926 // Pass optimization flags down to the linker.
929 // Pass debuginfo flags down to the linker.
932 // We want to prevent the compiler from accidentally leaking in any system
933 // libraries, so we explicitly ask gcc to not link to any libraries by
934 // default. Note that this does not happen for windows because windows pulls
935 // in some large number of libraries and I couldn't quite figure out which
937 if t.options.no_default_libraries {
938 cmd.no_default_libraries();
941 // Take careful note of the ordering of the arguments we pass to the linker
942 // here. Linkers will assume that things on the left depend on things to the
943 // right. Things on the right cannot depend on things on the left. This is
944 // all formally implemented in terms of resolving symbols (libs on the right
945 // resolve unknown symbols of libs on the left, but not vice versa).
947 // For this reason, we have organized the arguments we pass to the linker as
950 // 1. The local object that LLVM just generated
951 // 2. Local native libraries
952 // 3. Upstream rust libraries
953 // 4. Upstream native libraries
955 // The rationale behind this ordering is that those items lower down in the
956 // list can't depend on items higher up in the list. For example nothing can
957 // depend on what we just generated (e.g. that'd be a circular dependency).
958 // Upstream rust libraries are not allowed to depend on our local native
959 // libraries as that would violate the structure of the DAG, in that
960 // scenario they are required to link to them as well in a shared fashion.
962 // Note that upstream rust libraries may contain native dependencies as
963 // well, but they also can't depend on what we just started to add to the
964 // link line. And finally upstream native libraries can't depend on anything
965 // in this DAG so far because they're only dylibs and dylibs can only depend
966 // on other dylibs (e.g. other native deps).
967 add_local_native_libraries(cmd, sess);
968 add_upstream_rust_crates(cmd, sess, crate_type, tmpdir);
969 add_upstream_native_libraries(cmd, sess, crate_type);
971 // # Telling the linker what we're doing
973 if crate_type != config::CrateTypeExecutable {
974 cmd.build_dylib(out_filename);
977 // FIXME (#2397): At some point we want to rpath our guesses as to
978 // where extern libraries might live, based on the
979 // addl_lib_search_paths
980 if sess.opts.cg.rpath {
981 let sysroot = sess.sysroot();
982 let target_triple = &sess.opts.target_triple;
983 let mut get_install_prefix_lib_path = || {
984 let install_prefix = option_env!("CFG_PREFIX").expect("CFG_PREFIX");
985 let tlib = filesearch::relative_target_lib_path(sysroot, target_triple);
986 let mut path = PathBuf::from(install_prefix);
991 let mut rpath_config = RPathConfig {
992 used_crates: sess.cstore.used_crates(LinkagePreference::RequireDynamic),
993 out_filename: out_filename.to_path_buf(),
994 has_rpath: sess.target.target.options.has_rpath,
995 is_like_osx: sess.target.target.options.is_like_osx,
996 linker_is_gnu: sess.target.target.options.linker_is_gnu,
997 get_install_prefix_lib_path: &mut get_install_prefix_lib_path,
999 cmd.args(&rpath::get_rpath_flags(&mut rpath_config));
1002 // Finally add all the linker arguments provided on the command line along
1003 // with any #[link_args] attributes found inside the crate
1004 if let Some(ref args) = sess.opts.cg.link_args {
1007 cmd.args(&sess.opts.cg.link_arg);
1008 cmd.args(&used_link_args);
1011 // # Native library linking
1013 // User-supplied library search paths (-L on the command line). These are
1014 // the same paths used to find Rust crates, so some of them may have been
1015 // added already by the previous crate linking code. This only allows them
1016 // to be found at compile time so it is still entirely up to outside
1017 // forces to make sure that library can be found at runtime.
1019 // Also note that the native libraries linked here are only the ones located
1020 // in the current crate. Upstream crates with native library dependencies
1021 // may have their native library pulled in above.
1022 fn add_local_native_libraries(cmd: &mut Linker, sess: &Session) {
1023 sess.target_filesearch(PathKind::All).for_each_lib_search_path(|path, k| {
1025 PathKind::Framework => { cmd.framework_path(path); }
1026 _ => { cmd.include_path(&fix_windows_verbatim_for_gcc(path)); }
1030 let relevant_libs = sess.cstore.used_libraries().into_iter().filter(|l| {
1031 relevant_lib(sess, l)
1034 let search_path = archive_search_paths(sess);
1035 for lib in relevant_libs {
1037 NativeLibraryKind::NativeUnknown => cmd.link_dylib(&lib.name.as_str()),
1038 NativeLibraryKind::NativeFramework => cmd.link_framework(&lib.name.as_str()),
1039 NativeLibraryKind::NativeStaticNobundle => cmd.link_staticlib(&lib.name.as_str()),
1040 NativeLibraryKind::NativeStatic => cmd.link_whole_staticlib(&lib.name.as_str(),
1046 // # Rust Crate linking
1048 // Rust crates are not considered at all when creating an rlib output. All
1049 // dependencies will be linked when producing the final output (instead of
1050 // the intermediate rlib version)
1051 fn add_upstream_rust_crates(cmd: &mut Linker,
1053 crate_type: config::CrateType,
1055 // All of the heavy lifting has previously been accomplished by the
1056 // dependency_format module of the compiler. This is just crawling the
1057 // output of that module, adding crates as necessary.
1059 // Linking to a rlib involves just passing it to the linker (the linker
1060 // will slurp up the object files inside), and linking to a dynamic library
1061 // involves just passing the right -l flag.
1063 let formats = sess.dependency_formats.borrow();
1064 let data = formats.get(&crate_type).unwrap();
1066 // Invoke get_used_crates to ensure that we get a topological sorting of
1068 let deps = sess.cstore.used_crates(LinkagePreference::RequireDynamic);
1070 let mut compiler_builtins = None;
1072 for &(cnum, _) in &deps {
1073 // We may not pass all crates through to the linker. Some crates may
1074 // appear statically in an existing dylib, meaning we'll pick up all the
1075 // symbols from the dylib.
1076 let src = sess.cstore.used_crate_source(cnum);
1077 match data[cnum.as_usize() - 1] {
1078 _ if sess.cstore.is_sanitizer_runtime(cnum) => {
1079 link_sanitizer_runtime(cmd, sess, tmpdir, cnum);
1081 // compiler-builtins are always placed last to ensure that they're
1082 // linked correctly.
1083 _ if sess.cstore.is_compiler_builtins(cnum) => {
1084 assert!(compiler_builtins.is_none());
1085 compiler_builtins = Some(cnum);
1087 Linkage::NotLinked |
1088 Linkage::IncludedFromDylib => {}
1089 Linkage::Static => {
1090 add_static_crate(cmd, sess, tmpdir, crate_type, cnum);
1092 Linkage::Dynamic => {
1093 add_dynamic_crate(cmd, sess, &src.dylib.unwrap().0)
1098 // compiler-builtins are always placed last to ensure that they're
1099 // linked correctly.
1100 // We must always link the `compiler_builtins` crate statically. Even if it
1101 // was already "included" in a dylib (e.g. `libstd` when `-C prefer-dynamic`
1103 if let Some(cnum) = compiler_builtins {
1104 add_static_crate(cmd, sess, tmpdir, crate_type, cnum);
1107 // Converts a library file-stem into a cc -l argument
1108 fn unlib<'a>(config: &config::Config, stem: &'a str) -> &'a str {
1109 if stem.starts_with("lib") && !config.target.options.is_like_windows {
1116 // We must link the sanitizer runtime using -Wl,--whole-archive but since
1117 // it's packed in a .rlib, it contains stuff that are not objects that will
1118 // make the linker error. So we must remove those bits from the .rlib before
1120 fn link_sanitizer_runtime(cmd: &mut Linker,
1124 let src = sess.cstore.used_crate_source(cnum);
1125 let cratepath = &src.rlib.unwrap().0;
1127 if sess.target.target.options.is_like_osx {
1128 // On Apple platforms, the sanitizer is always built as a dylib, and
1129 // LLVM will link to `@rpath/*.dylib`, so we need to specify an
1130 // rpath to the library as well (the rpath should be absolute, see
1131 // PR #41352 for details).
1133 // FIXME: Remove this logic into librustc_*san once Cargo supports it
1134 let rpath = cratepath.parent().unwrap();
1135 let rpath = rpath.to_str().expect("non-utf8 component in path");
1136 cmd.args(&["-Wl,-rpath".into(), "-Xlinker".into(), rpath.into()]);
1139 let dst = tmpdir.join(cratepath.file_name().unwrap());
1140 let cfg = archive_config(sess, &dst, Some(cratepath));
1141 let mut archive = ArchiveBuilder::new(cfg);
1142 archive.update_symbols();
1144 for f in archive.src_files() {
1145 if f.ends_with("bytecode.deflate") || f == METADATA_FILENAME {
1146 archive.remove_file(&f);
1153 cmd.link_whole_rlib(&dst);
1156 // Adds the static "rlib" versions of all crates to the command line.
1157 // There's a bit of magic which happens here specifically related to LTO and
1158 // dynamic libraries. Specifically:
1160 // * For LTO, we remove upstream object files.
1161 // * For dylibs we remove metadata and bytecode from upstream rlibs
1163 // When performing LTO, almost(*) all of the bytecode from the upstream
1164 // libraries has already been included in our object file output. As a
1165 // result we need to remove the object files in the upstream libraries so
1166 // the linker doesn't try to include them twice (or whine about duplicate
1167 // symbols). We must continue to include the rest of the rlib, however, as
1168 // it may contain static native libraries which must be linked in.
1170 // (*) Crates marked with `#![no_builtins]` don't participate in LTO and
1171 // their bytecode wasn't included. The object files in those libraries must
1172 // still be passed to the linker.
1174 // When making a dynamic library, linkers by default don't include any
1175 // object files in an archive if they're not necessary to resolve the link.
1176 // We basically want to convert the archive (rlib) to a dylib, though, so we
1177 // *do* want everything included in the output, regardless of whether the
1178 // linker thinks it's needed or not. As a result we must use the
1179 // --whole-archive option (or the platform equivalent). When using this
1180 // option the linker will fail if there are non-objects in the archive (such
1181 // as our own metadata and/or bytecode). All in all, for rlibs to be
1182 // entirely included in dylibs, we need to remove all non-object files.
1184 // Note, however, that if we're not doing LTO or we're not producing a dylib
1185 // (aka we're making an executable), we can just pass the rlib blindly to
1186 // the linker (fast) because it's fine if it's not actually included as
1187 // we're at the end of the dependency chain.
1188 fn add_static_crate(cmd: &mut Linker,
1191 crate_type: config::CrateType,
1193 let src = sess.cstore.used_crate_source(cnum);
1194 let cratepath = &src.rlib.unwrap().0;
1196 // See the comment above in `link_staticlib` and `link_rlib` for why if
1197 // there's a static library that's not relevant we skip all object
1199 let native_libs = sess.cstore.native_libraries(cnum);
1200 let skip_native = native_libs.iter().any(|lib| {
1201 lib.kind == NativeLibraryKind::NativeStatic && !relevant_lib(sess, lib)
1204 if !sess.lto() && crate_type != config::CrateTypeDylib && !skip_native {
1205 cmd.link_rlib(&fix_windows_verbatim_for_gcc(cratepath));
1209 let dst = tmpdir.join(cratepath.file_name().unwrap());
1210 let name = cratepath.file_name().unwrap().to_str().unwrap();
1211 let name = &name[3..name.len() - 5]; // chop off lib/.rlib
1213 time(sess.time_passes(), &format!("altering {}.rlib", name), || {
1214 let cfg = archive_config(sess, &dst, Some(cratepath));
1215 let mut archive = ArchiveBuilder::new(cfg);
1216 archive.update_symbols();
1218 let mut any_objects = false;
1219 for f in archive.src_files() {
1220 if f.ends_with("bytecode.deflate") || f == METADATA_FILENAME {
1221 archive.remove_file(&f);
1225 let canonical = f.replace("-", "_");
1226 let canonical_name = name.replace("-", "_");
1228 let is_rust_object =
1229 canonical.starts_with(&canonical_name) && {
1230 let num = &f[name.len()..f.len() - 2];
1231 num.len() > 0 && num[1..].parse::<u32>().is_ok()
1234 // If we've been requested to skip all native object files
1235 // (those not generated by the rust compiler) then we can skip
1236 // this file. See above for why we may want to do this.
1237 let skip_because_cfg_say_so = skip_native && !is_rust_object;
1239 // If we're performing LTO and this is a rust-generated object
1240 // file, then we don't need the object file as it's part of the
1241 // LTO module. Note that `#![no_builtins]` is excluded from LTO,
1242 // though, so we let that object file slide.
1243 let skip_because_lto = sess.lto() && is_rust_object &&
1244 !sess.cstore.is_no_builtins(cnum);
1246 if skip_because_cfg_say_so || skip_because_lto {
1247 archive.remove_file(&f);
1258 // If we're creating a dylib, then we need to include the
1259 // whole of each object in our archive into that artifact. This is
1260 // because a `dylib` can be reused as an intermediate artifact.
1262 // Note, though, that we don't want to include the whole of a
1263 // compiler-builtins crate (e.g. compiler-rt) because it'll get
1264 // repeatedly linked anyway.
1265 if crate_type == config::CrateTypeDylib &&
1266 !sess.cstore.is_compiler_builtins(cnum) {
1267 cmd.link_whole_rlib(&fix_windows_verbatim_for_gcc(&dst));
1269 cmd.link_rlib(&fix_windows_verbatim_for_gcc(&dst));
1274 // Same thing as above, but for dynamic crates instead of static crates.
1275 fn add_dynamic_crate(cmd: &mut Linker, sess: &Session, cratepath: &Path) {
1276 // If we're performing LTO, then it should have been previously required
1277 // that all upstream rust dependencies were available in an rlib format.
1278 assert!(!sess.lto());
1280 // Just need to tell the linker about where the library lives and
1282 let parent = cratepath.parent();
1283 if let Some(dir) = parent {
1284 cmd.include_path(&fix_windows_verbatim_for_gcc(dir));
1286 let filestem = cratepath.file_stem().unwrap().to_str().unwrap();
1287 cmd.link_rust_dylib(&unlib(&sess.target, filestem),
1288 parent.unwrap_or(Path::new("")));
1292 // Link in all of our upstream crates' native dependencies. Remember that
1293 // all of these upstream native dependencies are all non-static
1294 // dependencies. We've got two cases then:
1296 // 1. The upstream crate is an rlib. In this case we *must* link in the
1297 // native dependency because the rlib is just an archive.
1299 // 2. The upstream crate is a dylib. In order to use the dylib, we have to
1300 // have the dependency present on the system somewhere. Thus, we don't
1301 // gain a whole lot from not linking in the dynamic dependency to this
1304 // The use case for this is a little subtle. In theory the native
1305 // dependencies of a crate are purely an implementation detail of the crate
1306 // itself, but the problem arises with generic and inlined functions. If a
1307 // generic function calls a native function, then the generic function must
1308 // be instantiated in the target crate, meaning that the native symbol must
1309 // also be resolved in the target crate.
1310 fn add_upstream_native_libraries(cmd: &mut Linker, sess: &Session, crate_type: config::CrateType) {
1311 // Be sure to use a topological sorting of crates because there may be
1312 // interdependencies between native libraries. When passing -nodefaultlibs,
1313 // for example, almost all native libraries depend on libc, so we have to
1314 // make sure that's all the way at the right (liblibc is near the base of
1315 // the dependency chain).
1317 // This passes RequireStatic, but the actual requirement doesn't matter,
1318 // we're just getting an ordering of crate numbers, we're not worried about
1320 let formats = sess.dependency_formats.borrow();
1321 let data = formats.get(&crate_type).unwrap();
1323 let crates = sess.cstore.used_crates(LinkagePreference::RequireStatic);
1324 for (cnum, _) in crates {
1325 for lib in sess.cstore.native_libraries(cnum) {
1326 if !relevant_lib(sess, &lib) {
1330 NativeLibraryKind::NativeUnknown => cmd.link_dylib(&lib.name.as_str()),
1331 NativeLibraryKind::NativeFramework => cmd.link_framework(&lib.name.as_str()),
1332 NativeLibraryKind::NativeStaticNobundle => {
1333 // Link "static-nobundle" native libs only if the crate they originate from
1334 // is being linked statically to the current crate. If it's linked dynamically
1335 // or is an rlib already included via some other dylib crate, the symbols from
1336 // native libs will have already been included in that dylib.
1337 if data[cnum.as_usize() - 1] == Linkage::Static {
1338 cmd.link_staticlib(&lib.name.as_str())
1341 // ignore statically included native libraries here as we've
1342 // already included them when we included the rust library
1344 NativeLibraryKind::NativeStatic => {}
1350 fn relevant_lib(sess: &Session, lib: &NativeLibrary) -> bool {
1352 Some(ref cfg) => attr::cfg_matches(cfg, &sess.parse_sess, None),