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::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;
50 /// The LLVM module name containing crate-metadata. This includes a `.` on
51 /// purpose, so it cannot clash with the name of a user-defined module.
52 pub const METADATA_MODULE_NAME: &'static str = "crate.metadata";
53 /// The name of the crate-metadata object file the compiler generates. Must
54 /// match up with `METADATA_MODULE_NAME`.
55 pub const METADATA_OBJ_NAME: &'static str = "crate.metadata.o";
57 // RLIB LLVM-BYTECODE OBJECT LAYOUT
60 // 0..10 "RUST_OBJECT" encoded in ASCII
61 // 11..14 format version as little-endian u32
62 // 15..22 size in bytes of deflate compressed LLVM bitcode as
64 // 23.. compressed LLVM bitcode
66 // This is the "magic number" expected at the beginning of a LLVM bytecode
68 pub const RLIB_BYTECODE_OBJECT_MAGIC: &'static [u8] = b"RUST_OBJECT";
70 // The version number this compiler will write to bytecode objects in rlibs
71 pub const RLIB_BYTECODE_OBJECT_VERSION: u32 = 1;
73 // The offset in bytes the bytecode object format version number can be found at
74 pub const RLIB_BYTECODE_OBJECT_VERSION_OFFSET: usize = 11;
76 // The offset in bytes the size of the compressed bytecode can be found at in
78 pub const RLIB_BYTECODE_OBJECT_V1_DATASIZE_OFFSET: usize =
79 RLIB_BYTECODE_OBJECT_VERSION_OFFSET + 4;
81 // The offset in bytes the compressed LLVM bytecode can be found at in format
83 pub const RLIB_BYTECODE_OBJECT_V1_DATA_OFFSET: usize =
84 RLIB_BYTECODE_OBJECT_V1_DATASIZE_OFFSET + 8;
87 pub fn find_crate_name(sess: Option<&Session>,
88 attrs: &[ast::Attribute],
89 input: &Input) -> String {
90 let validate = |s: String, span: Option<Span>| {
91 cstore::validate_crate_name(sess, &s, span);
95 // Look in attributes 100% of the time to make sure the attribute is marked
96 // as used. After doing this, however, we still prioritize a crate name from
97 // the command line over one found in the #[crate_name] attribute. If we
98 // find both we ensure that they're the same later on as well.
99 let attr_crate_name = attrs.iter().find(|at| at.check_name("crate_name"))
100 .and_then(|at| at.value_str().map(|s| (at, s)));
102 if let Some(sess) = sess {
103 if let Some(ref s) = sess.opts.crate_name {
104 if let Some((attr, name)) = attr_crate_name {
106 let msg = format!("--crate-name and #[crate_name] are \
107 required to match, but `{}` != `{}`",
109 sess.span_err(attr.span, &msg);
112 return validate(s.clone(), None);
116 if let Some((attr, s)) = attr_crate_name {
117 return validate(s.to_string(), Some(attr.span));
119 if let Input::File(ref path) = *input {
120 if let Some(s) = path.file_stem().and_then(|s| s.to_str()) {
121 if s.starts_with("-") {
122 let msg = format!("crate names cannot start with a `-`, but \
123 `{}` has a leading hyphen", s);
124 if let Some(sess) = sess {
128 return validate(s.replace("-", "_"), None);
133 "rust_out".to_string()
136 pub fn build_link_meta(incremental_hashes_map: &IncrementalHashesMap) -> LinkMeta {
138 crate_hash: Svh::new(incremental_hashes_map[&DepNode::Krate].to_smaller_hash()),
144 // The third parameter is for an env vars, used to set up the path for MSVC
146 pub fn get_linker(sess: &Session) -> (String, Command, Vec<(OsString, OsString)>) {
147 if let Some(ref linker) = sess.opts.cg.linker {
148 (linker.clone(), Command::new(linker), vec![])
149 } else if sess.target.target.options.is_like_msvc {
150 let (cmd, envs) = msvc_link_exe_cmd(sess);
151 ("link.exe".to_string(), cmd, envs)
153 (sess.target.target.options.linker.clone(),
154 Command::new(&sess.target.target.options.linker), vec![])
159 pub fn msvc_link_exe_cmd(sess: &Session) -> (Command, Vec<(OsString, OsString)>) {
160 use gcc::windows_registry;
162 let target = &sess.opts.target_triple;
163 let tool = windows_registry::find_tool(target, "link.exe");
165 if let Some(tool) = tool {
166 let envs = tool.env().to_vec();
167 (tool.to_command(), envs)
169 debug!("Failed to locate linker.");
170 (Command::new("link.exe"), vec![])
175 pub fn msvc_link_exe_cmd(_sess: &Session) -> (Command, Vec<(OsString, OsString)>) {
176 (Command::new("link.exe"), vec![])
179 pub fn get_ar_prog(sess: &Session) -> String {
180 sess.opts.cg.ar.clone().unwrap_or_else(|| {
181 sess.target.target.options.ar.clone()
185 fn command_path(sess: &Session, extra: Option<PathBuf>) -> OsString {
186 // The compiler's sysroot often has some bundled tools, so add it to the
187 // PATH for the child.
188 let mut new_path = sess.host_filesearch(PathKind::All)
189 .get_tools_search_paths();
190 if let Some(path) = env::var_os("PATH") {
191 new_path.extend(env::split_paths(&path));
193 new_path.extend(extra);
194 env::join_paths(new_path).unwrap()
197 pub fn remove(sess: &Session, path: &Path) {
198 match fs::remove_file(path) {
201 sess.err(&format!("failed to remove {}: {}",
208 /// Perform the linkage portion of the compilation phase. This will generate all
209 /// of the requested outputs for this compilation session.
210 pub fn link_binary(sess: &Session,
211 trans: &CrateTranslation,
212 outputs: &OutputFilenames,
213 crate_name: &str) -> Vec<PathBuf> {
214 let mut out_filenames = Vec::new();
215 for &crate_type in sess.crate_types.borrow().iter() {
216 // Ignore executable crates if we have -Z no-trans, as they will error.
217 if (sess.opts.debugging_opts.no_trans ||
218 !sess.opts.output_types.should_trans()) &&
219 crate_type == config::CrateTypeExecutable {
223 if invalid_output_for_target(sess, crate_type) {
224 bug!("invalid output type `{:?}` for target os `{}`",
225 crate_type, sess.opts.target_triple);
227 let mut out_files = link_binary_output(sess, trans, crate_type, outputs, crate_name);
228 out_filenames.append(&mut out_files);
231 // Remove the temporary object file and metadata if we aren't saving temps
232 if !sess.opts.cg.save_temps {
233 if sess.opts.output_types.should_trans() {
234 for obj in object_filenames(trans, outputs) {
238 remove(sess, &outputs.with_extension(METADATA_OBJ_NAME));
245 /// Returns default crate type for target
247 /// Default crate type is used when crate type isn't provided neither
248 /// through cmd line arguments nor through crate attributes
250 /// It is CrateTypeExecutable for all platforms but iOS as there is no
251 /// way to run iOS binaries anyway without jailbreaking and
252 /// interaction with Rust code through static library is the only
254 pub fn default_output_for_target(sess: &Session) -> config::CrateType {
255 if !sess.target.target.options.executables {
256 config::CrateTypeStaticlib
258 config::CrateTypeExecutable
262 /// Checks if target supports crate_type as output
263 pub fn invalid_output_for_target(sess: &Session,
264 crate_type: config::CrateType) -> bool {
265 match (sess.target.target.options.dynamic_linking,
266 sess.target.target.options.executables, crate_type) {
267 (false, _, config::CrateTypeCdylib) |
268 (false, _, config::CrateTypeProcMacro) |
269 (false, _, config::CrateTypeDylib) => true,
270 (_, false, config::CrateTypeExecutable) => true,
275 fn is_writeable(p: &Path) -> bool {
278 Ok(m) => !m.permissions().readonly()
282 fn filename_for_metadata(sess: &Session, crate_name: &str, outputs: &OutputFilenames) -> PathBuf {
283 let out_filename = outputs.single_output_file.clone()
286 .join(&format!("lib{}{}.rmeta", crate_name, sess.opts.cg.extra_filename)));
287 check_file_is_writeable(&out_filename, sess);
291 pub fn filename_for_input(sess: &Session,
292 crate_type: config::CrateType,
294 outputs: &OutputFilenames) -> PathBuf {
295 let libname = format!("{}{}", crate_name, sess.opts.cg.extra_filename);
298 config::CrateTypeRlib => {
299 outputs.out_directory.join(&format!("lib{}.rlib", libname))
301 config::CrateTypeCdylib |
302 config::CrateTypeProcMacro |
303 config::CrateTypeDylib => {
304 let (prefix, suffix) = (&sess.target.target.options.dll_prefix,
305 &sess.target.target.options.dll_suffix);
306 outputs.out_directory.join(&format!("{}{}{}", prefix, libname,
309 config::CrateTypeStaticlib => {
310 let (prefix, suffix) = (&sess.target.target.options.staticlib_prefix,
311 &sess.target.target.options.staticlib_suffix);
312 outputs.out_directory.join(&format!("{}{}{}", prefix, libname,
315 config::CrateTypeExecutable => {
316 let suffix = &sess.target.target.options.exe_suffix;
317 let out_filename = outputs.path(OutputType::Exe);
318 if suffix.is_empty() {
319 out_filename.to_path_buf()
321 out_filename.with_extension(&suffix[1..])
327 pub fn each_linked_rlib(sess: &Session,
328 f: &mut FnMut(CrateNum, &Path)) {
329 let crates = sess.cstore.used_crates(LinkagePreference::RequireStatic).into_iter();
330 let fmts = sess.dependency_formats.borrow();
331 let fmts = fmts.get(&config::CrateTypeExecutable)
332 .or_else(|| fmts.get(&config::CrateTypeStaticlib))
333 .or_else(|| fmts.get(&config::CrateTypeCdylib))
334 .or_else(|| fmts.get(&config::CrateTypeProcMacro));
335 let fmts = fmts.unwrap_or_else(|| {
336 bug!("could not find formats for rlibs");
338 for (cnum, path) in crates {
339 match fmts[cnum.as_usize() - 1] {
340 Linkage::NotLinked | Linkage::IncludedFromDylib => continue,
343 let name = sess.cstore.crate_name(cnum).clone();
344 let path = match path {
345 LibSource::Some(p) => p,
346 LibSource::MetadataOnly => {
347 sess.fatal(&format!("could not find rlib for: `{}`, found rmeta (metadata) file",
351 sess.fatal(&format!("could not find rlib for: `{}`", name));
358 fn out_filename(sess: &Session,
359 crate_type: config::CrateType,
360 outputs: &OutputFilenames,
363 let default_filename = filename_for_input(sess, crate_type, crate_name, outputs);
364 let out_filename = outputs.outputs.get(&OutputType::Exe)
365 .and_then(|s| s.to_owned())
366 .or_else(|| outputs.single_output_file.clone())
367 .unwrap_or(default_filename);
369 check_file_is_writeable(&out_filename, sess);
374 // Make sure files are writeable. Mac, FreeBSD, and Windows system linkers
375 // check this already -- however, the Linux linker will happily overwrite a
376 // read-only file. We should be consistent.
377 fn check_file_is_writeable(file: &Path, sess: &Session) {
378 if !is_writeable(file) {
379 sess.fatal(&format!("output file {} is not writeable -- check its \
380 permissions", file.display()));
384 fn link_binary_output(sess: &Session,
385 trans: &CrateTranslation,
386 crate_type: config::CrateType,
387 outputs: &OutputFilenames,
388 crate_name: &str) -> Vec<PathBuf> {
389 let objects = object_filenames(trans, outputs);
391 for file in &objects {
392 check_file_is_writeable(file, sess);
395 let tmpdir = match TempDir::new("rustc") {
396 Ok(tmpdir) => tmpdir,
397 Err(err) => sess.fatal(&format!("couldn't create a temp dir: {}", err)),
400 let mut out_filenames = vec![];
402 if outputs.outputs.contains_key(&OutputType::Metadata) {
403 let out_filename = filename_for_metadata(sess, crate_name, outputs);
404 emit_metadata(sess, trans, &out_filename);
405 out_filenames.push(out_filename);
408 if outputs.outputs.should_trans() {
409 let out_filename = out_filename(sess, crate_type, outputs, crate_name);
411 config::CrateTypeRlib => {
412 link_rlib(sess, Some(trans), &objects, &out_filename,
413 tmpdir.path()).build();
415 config::CrateTypeStaticlib => {
416 link_staticlib(sess, &objects, &out_filename, tmpdir.path());
419 link_natively(sess, crate_type, &objects, &out_filename, trans,
420 outputs, tmpdir.path());
423 out_filenames.push(out_filename);
429 fn object_filenames(trans: &CrateTranslation,
430 outputs: &OutputFilenames)
432 trans.modules.iter().map(|module| {
433 outputs.temp_path(OutputType::Object, Some(&module.name))
437 fn archive_search_paths(sess: &Session) -> Vec<PathBuf> {
438 let mut search = Vec::new();
439 sess.target_filesearch(PathKind::Native).for_each_lib_search_path(|path, _| {
440 search.push(path.to_path_buf());
445 fn archive_config<'a>(sess: &'a Session,
447 input: Option<&Path>) -> ArchiveConfig<'a> {
450 dst: output.to_path_buf(),
451 src: input.map(|p| p.to_path_buf()),
452 lib_search_paths: archive_search_paths(sess),
453 ar_prog: get_ar_prog(sess),
454 command_path: command_path(sess, None),
458 fn emit_metadata<'a>(sess: &'a Session, trans: &CrateTranslation, out_filename: &Path) {
459 let result = fs::File::create(out_filename).and_then(|mut f| {
460 f.write_all(&trans.metadata.raw_data)
463 if let Err(e) = result {
464 sess.fatal(&format!("failed to write {}: {}", out_filename.display(), e));
470 // An rlib in its current incarnation is essentially a renamed .a file. The
471 // rlib primarily contains the object file of the crate, but it also contains
472 // all of the object files from native libraries. This is done by unzipping
473 // native libraries and inserting all of the contents into this archive.
474 fn link_rlib<'a>(sess: &'a Session,
475 trans: Option<&CrateTranslation>, // None == no metadata/bytecode
478 tmpdir: &Path) -> ArchiveBuilder<'a> {
479 info!("preparing rlib from {:?} to {:?}", objects, out_filename);
480 let mut ab = ArchiveBuilder::new(archive_config(sess, out_filename, None));
486 // Note that in this loop we are ignoring the value of `lib.cfg`. That is,
487 // we may not be configured to actually include a static library if we're
488 // adding it here. That's because later when we consume this rlib we'll
489 // decide whether we actually needed the static library or not.
491 // To do this "correctly" we'd need to keep track of which libraries added
492 // which object files to the archive. We don't do that here, however. The
493 // #[link(cfg(..))] feature is unstable, though, and only intended to get
494 // liblibc working. In that sense the check below just indicates that if
495 // there are any libraries we want to omit object files for at link time we
496 // just exclude all custom object files.
498 // Eventually if we want to stabilize or flesh out the #[link(cfg(..))]
499 // feature then we'll need to figure out how to record what objects were
500 // loaded from the libraries found here and then encode that into the
501 // metadata of the rlib we're generating somehow.
502 for lib in sess.cstore.used_libraries() {
504 NativeLibraryKind::NativeStatic => {}
505 NativeLibraryKind::NativeStaticNobundle |
506 NativeLibraryKind::NativeFramework |
507 NativeLibraryKind::NativeUnknown => continue,
509 ab.add_native_library(&lib.name.as_str());
512 // After adding all files to the archive, we need to update the
513 // symbol table of the archive.
516 // Note that it is important that we add all of our non-object "magical
517 // files" *after* all of the object files in the archive. The reason for
518 // this is as follows:
520 // * When performing LTO, this archive will be modified to remove
521 // objects from above. The reason for this is described below.
523 // * When the system linker looks at an archive, it will attempt to
524 // determine the architecture of the archive in order to see whether its
527 // The algorithm for this detection is: iterate over the files in the
528 // archive. Skip magical SYMDEF names. Interpret the first file as an
529 // object file. Read architecture from the object file.
531 // * As one can probably see, if "metadata" and "foo.bc" were placed
532 // before all of the objects, then the architecture of this archive would
533 // not be correctly inferred once 'foo.o' is removed.
535 // Basically, all this means is that this code should not move above the
539 // Instead of putting the metadata in an object file section, rlibs
540 // contain the metadata in a separate file. We use a temp directory
541 // here so concurrent builds in the same directory don't try to use
542 // the same filename for metadata (stomping over one another)
543 let metadata = tmpdir.join(METADATA_FILENAME);
544 emit_metadata(sess, trans, &metadata);
545 ab.add_file(&metadata);
547 // For LTO purposes, the bytecode of this library is also inserted
548 // into the archive. If codegen_units > 1, we insert each of the
551 // Note that we make sure that the bytecode filename in the
552 // archive is never exactly 16 bytes long by adding a 16 byte
553 // extension to it. This is to work around a bug in LLDB that
554 // would cause it to crash if the name of a file in an archive
555 // was exactly 16 bytes.
556 let bc_filename = obj.with_extension("bc");
557 let bc_deflated_filename = tmpdir.join({
558 obj.with_extension("bytecode.deflate").file_name().unwrap()
561 let mut bc_data = Vec::new();
562 match fs::File::open(&bc_filename).and_then(|mut f| {
563 f.read_to_end(&mut bc_data)
566 Err(e) => sess.fatal(&format!("failed to read bytecode: {}",
570 let bc_data_deflated = flate::deflate_bytes(&bc_data);
572 let mut bc_file_deflated = match fs::File::create(&bc_deflated_filename) {
575 sess.fatal(&format!("failed to create compressed \
576 bytecode file: {}", e))
580 match write_rlib_bytecode_object_v1(&mut bc_file_deflated,
584 sess.fatal(&format!("failed to write compressed \
589 ab.add_file(&bc_deflated_filename);
591 // See the bottom of back::write::run_passes for an explanation
592 // of when we do and don't keep .#module-name#.bc files around.
593 let user_wants_numbered_bitcode =
594 sess.opts.output_types.contains_key(&OutputType::Bitcode) &&
595 sess.opts.cg.codegen_units > 1;
596 if !sess.opts.cg.save_temps && !user_wants_numbered_bitcode {
597 remove(sess, &bc_filename);
601 // After adding all files to the archive, we need to update the
602 // symbol table of the archive. This currently dies on macOS (see
603 // #11162), and isn't necessary there anyway
604 if !sess.target.target.options.is_like_osx {
615 fn write_rlib_bytecode_object_v1(writer: &mut Write,
616 bc_data_deflated: &[u8]) -> io::Result<()> {
617 let bc_data_deflated_size: u64 = bc_data_deflated.len() as u64;
619 writer.write_all(RLIB_BYTECODE_OBJECT_MAGIC)?;
620 writer.write_all(&[1, 0, 0, 0])?;
622 (bc_data_deflated_size >> 0) as u8,
623 (bc_data_deflated_size >> 8) as u8,
624 (bc_data_deflated_size >> 16) as u8,
625 (bc_data_deflated_size >> 24) as u8,
626 (bc_data_deflated_size >> 32) as u8,
627 (bc_data_deflated_size >> 40) as u8,
628 (bc_data_deflated_size >> 48) as u8,
629 (bc_data_deflated_size >> 56) as u8,
631 writer.write_all(&bc_data_deflated)?;
633 let number_of_bytes_written_so_far =
634 RLIB_BYTECODE_OBJECT_MAGIC.len() + // magic id
635 mem::size_of_val(&RLIB_BYTECODE_OBJECT_VERSION) + // version
636 mem::size_of_val(&bc_data_deflated_size) + // data size field
637 bc_data_deflated_size as usize; // actual data
639 // If the number of bytes written to the object so far is odd, add a
640 // padding byte to make it even. This works around a crash bug in LLDB
641 // (see issue #15950)
642 if number_of_bytes_written_so_far % 2 == 1 {
643 writer.write_all(&[0])?;
649 // Create a static archive
651 // This is essentially the same thing as an rlib, but it also involves adding
652 // all of the upstream crates' objects into the archive. This will slurp in
653 // all of the native libraries of upstream dependencies as well.
655 // Additionally, there's no way for us to link dynamic libraries, so we warn
656 // about all dynamic library dependencies that they're not linked in.
658 // There's no need to include metadata in a static archive, so ensure to not
659 // link in the metadata object file (and also don't prepare the archive with a
661 fn link_staticlib(sess: &Session, objects: &[PathBuf], out_filename: &Path,
663 let mut ab = link_rlib(sess, None, objects, out_filename, tempdir);
664 let mut all_native_libs = vec![];
666 each_linked_rlib(sess, &mut |cnum, path| {
667 let name = sess.cstore.crate_name(cnum);
668 let native_libs = sess.cstore.native_libraries(cnum);
670 // Here when we include the rlib into our staticlib we need to make a
671 // decision whether to include the extra object files along the way.
672 // These extra object files come from statically included native
673 // libraries, but they may be cfg'd away with #[link(cfg(..))].
675 // This unstable feature, though, only needs liblibc to work. The only
676 // use case there is where musl is statically included in liblibc.rlib,
677 // so if we don't want the included version we just need to skip it. As
678 // a result the logic here is that if *any* linked library is cfg'd away
679 // we just skip all object files.
681 // Clearly this is not sufficient for a general purpose feature, and
682 // we'd want to read from the library's metadata to determine which
683 // object files come from where and selectively skip them.
684 let skip_object_files = native_libs.iter().any(|lib| {
685 lib.kind == NativeLibraryKind::NativeStatic && !relevant_lib(sess, lib)
687 ab.add_rlib(path, &name.as_str(), sess.lto(), skip_object_files).unwrap();
689 all_native_libs.extend(sess.cstore.native_libraries(cnum));
695 if !all_native_libs.is_empty() {
696 sess.note_without_error("link against the following native artifacts when linking against \
697 this static library");
698 sess.note_without_error("the order and any duplication can be significant on some \
699 platforms, and so may need to be preserved");
702 for lib in all_native_libs.iter().filter(|l| relevant_lib(sess, l)) {
703 let name = match lib.kind {
704 NativeLibraryKind::NativeStaticNobundle |
705 NativeLibraryKind::NativeUnknown => "library",
706 NativeLibraryKind::NativeFramework => "framework",
707 // These are included, no need to print them
708 NativeLibraryKind::NativeStatic => continue,
710 sess.note_without_error(&format!("{}: {}", name, lib.name));
714 // Create a dynamic library or executable
716 // This will invoke the system linker/cc to create the resulting file. This
717 // links to all upstream files as well.
718 fn link_natively(sess: &Session,
719 crate_type: config::CrateType,
722 trans: &CrateTranslation,
723 outputs: &OutputFilenames,
725 info!("preparing {:?} from {:?} to {:?}", crate_type, objects, out_filename);
726 let flavor = sess.linker_flavor();
728 // The invocations of cc share some flags across platforms
729 let (pname, mut cmd, envs) = get_linker(sess);
730 // This will set PATH on MSVC
733 let root = sess.target_filesearch(PathKind::Native).get_lib_path();
734 if let Some(args) = sess.target.target.options.pre_link_args.get(&flavor) {
737 if let Some(ref args) = sess.opts.debugging_opts.pre_link_args {
740 cmd.args(&sess.opts.debugging_opts.pre_link_arg);
742 let pre_link_objects = if crate_type == config::CrateTypeExecutable {
743 &sess.target.target.options.pre_link_objects_exe
745 &sess.target.target.options.pre_link_objects_dll
747 for obj in pre_link_objects {
748 cmd.arg(root.join(obj));
751 if sess.target.target.options.is_like_emscripten {
753 cmd.arg(if sess.panic_strategy() == PanicStrategy::Abort {
754 "DISABLE_EXCEPTION_CATCHING=1"
756 "DISABLE_EXCEPTION_CATCHING=0"
761 let mut linker = trans.linker_info.to_linker(cmd, &sess);
762 link_args(&mut *linker, sess, crate_type, tmpdir,
763 objects, out_filename, outputs, trans);
764 cmd = linker.finalize();
766 if let Some(args) = sess.target.target.options.late_link_args.get(&flavor) {
769 for obj in &sess.target.target.options.post_link_objects {
770 cmd.arg(root.join(obj));
772 if let Some(args) = sess.target.target.options.post_link_args.get(&flavor) {
776 if sess.opts.debugging_opts.print_link_args {
777 println!("{:?}", &cmd);
780 // May have not found libraries in the right formats.
781 sess.abort_if_errors();
783 // Invoke the system linker
785 // Note that there's a terribly awful hack that really shouldn't be present
786 // in any compiler. Here an environment variable is supported to
787 // automatically retry the linker invocation if the linker looks like it
790 // Gee that seems odd, normally segfaults are things we want to know about!
791 // Unfortunately though in rust-lang/rust#38878 we're experiencing the
792 // linker segfaulting on Travis quite a bit which is causing quite a bit of
793 // pain to land PRs when they spuriously fail due to a segfault.
795 // The issue #38878 has some more debugging information on it as well, but
796 // this unfortunately looks like it's just a race condition in macOS's linker
797 // with some thread pool working in the background. It seems that no one
798 // currently knows a fix for this so in the meantime we're left with this...
800 let retry_on_segfault = env::var("RUSTC_RETRY_LINKER_ON_SEGFAULT").is_ok();
805 prog = time(sess.time_passes(), "running linker", || cmd.output());
806 if !retry_on_segfault || i > 3 {
809 let output = match prog {
810 Ok(ref output) => output,
813 if output.status.success() {
816 let mut out = output.stderr.clone();
817 out.extend(&output.stdout);
818 let out = String::from_utf8_lossy(&out);
819 let msg = "clang: error: unable to execute command: \
820 Segmentation fault: 11";
821 if !out.contains(msg) {
825 sess.struct_warn("looks like the linker segfaulted when we tried to \
826 call it, automatically retrying again")
827 .note(&format!("{:?}", cmd))
834 fn escape_string(s: &[u8]) -> String {
835 str::from_utf8(s).map(|s| s.to_owned())
836 .unwrap_or_else(|_| {
837 let mut x = "Non-UTF-8 output: ".to_string();
839 .flat_map(|&b| ascii::escape_default(b))
840 .map(|b| char::from_u32(b as u32).unwrap()));
844 if !prog.status.success() {
845 let mut output = prog.stderr.clone();
846 output.extend_from_slice(&prog.stdout);
847 sess.struct_err(&format!("linking with `{}` failed: {}",
850 .note(&format!("{:?}", &cmd))
851 .note(&escape_string(&output))
853 sess.abort_if_errors();
855 info!("linker stderr:\n{}", escape_string(&prog.stderr));
856 info!("linker stdout:\n{}", escape_string(&prog.stdout));
859 sess.struct_err(&format!("could not exec the linker `{}`: {}", pname, e))
860 .note(&format!("{:?}", &cmd))
862 if sess.target.target.options.is_like_msvc && e.kind() == io::ErrorKind::NotFound {
863 sess.note_without_error("the msvc targets depend on the msvc linker \
864 but `link.exe` was not found");
865 sess.note_without_error("please ensure that VS 2013 or VS 2015 was installed \
866 with the Visual C++ option");
868 sess.abort_if_errors();
873 // On macOS, debuggers need this utility to get run to do some munging of
875 if sess.target.target.options.is_like_osx && sess.opts.debuginfo != NoDebugInfo {
876 match Command::new("dsymutil").arg(out_filename).output() {
878 Err(e) => sess.fatal(&format!("failed to run dsymutil: {}", e)),
883 fn link_args(cmd: &mut Linker,
885 crate_type: config::CrateType,
889 outputs: &OutputFilenames,
890 trans: &CrateTranslation) {
892 // The default library location, we need this to find the runtime.
893 // The location of crates will be determined as needed.
894 let lib_path = sess.target_filesearch(PathKind::All).get_lib_path();
897 let t = &sess.target.target;
899 cmd.include_path(&fix_windows_verbatim_for_gcc(&lib_path));
903 cmd.output_filename(out_filename);
905 if crate_type == config::CrateTypeExecutable &&
906 sess.target.target.options.is_like_windows {
907 if let Some(ref s) = trans.windows_subsystem {
912 // If we're building a dynamic library then some platforms need to make sure
913 // that all symbols are exported correctly from the dynamic library.
914 if crate_type != config::CrateTypeExecutable ||
915 sess.target.target.options.is_like_emscripten {
916 cmd.export_symbols(tmpdir, crate_type);
919 // When linking a dynamic library, we put the metadata into a section of the
920 // executable. This metadata is in a separate object file from the main
921 // object file, so we link that in here.
922 if crate_type == config::CrateTypeDylib ||
923 crate_type == config::CrateTypeProcMacro {
924 cmd.add_object(&outputs.with_extension(METADATA_OBJ_NAME));
927 // Try to strip as much out of the generated object by removing unused
928 // sections if possible. See more comments in linker.rs
929 if !sess.opts.cg.link_dead_code {
930 let keep_metadata = crate_type == config::CrateTypeDylib;
931 cmd.gc_sections(keep_metadata);
934 let used_link_args = sess.cstore.used_link_args();
936 if crate_type == config::CrateTypeExecutable &&
937 t.options.position_independent_executables {
938 let empty_vec = Vec::new();
939 let args = sess.opts.cg.link_args.as_ref().unwrap_or(&empty_vec);
940 let more_args = &sess.opts.cg.link_arg;
941 let mut args = args.iter().chain(more_args.iter()).chain(used_link_args.iter());
943 if get_reloc_model(sess) == llvm::RelocMode::PIC
944 && !args.any(|x| *x == "-static") {
945 cmd.position_independent_executable();
949 // Pass optimization flags down to the linker.
952 // Pass debuginfo flags down to the linker.
955 // We want to prevent the compiler from accidentally leaking in any system
956 // libraries, so we explicitly ask gcc to not link to any libraries by
957 // default. Note that this does not happen for windows because windows pulls
958 // in some large number of libraries and I couldn't quite figure out which
960 if t.options.no_default_libraries {
961 cmd.no_default_libraries();
964 // Take careful note of the ordering of the arguments we pass to the linker
965 // here. Linkers will assume that things on the left depend on things to the
966 // right. Things on the right cannot depend on things on the left. This is
967 // all formally implemented in terms of resolving symbols (libs on the right
968 // resolve unknown symbols of libs on the left, but not vice versa).
970 // For this reason, we have organized the arguments we pass to the linker as
973 // 1. The local object that LLVM just generated
974 // 2. Local native libraries
975 // 3. Upstream rust libraries
976 // 4. Upstream native libraries
978 // The rationale behind this ordering is that those items lower down in the
979 // list can't depend on items higher up in the list. For example nothing can
980 // depend on what we just generated (e.g. that'd be a circular dependency).
981 // Upstream rust libraries are not allowed to depend on our local native
982 // libraries as that would violate the structure of the DAG, in that
983 // scenario they are required to link to them as well in a shared fashion.
985 // Note that upstream rust libraries may contain native dependencies as
986 // well, but they also can't depend on what we just started to add to the
987 // link line. And finally upstream native libraries can't depend on anything
988 // in this DAG so far because they're only dylibs and dylibs can only depend
989 // on other dylibs (e.g. other native deps).
990 add_local_native_libraries(cmd, sess);
991 add_upstream_rust_crates(cmd, sess, crate_type, tmpdir);
992 add_upstream_native_libraries(cmd, sess, crate_type);
994 // # Telling the linker what we're doing
996 if crate_type != config::CrateTypeExecutable {
997 cmd.build_dylib(out_filename);
1000 // FIXME (#2397): At some point we want to rpath our guesses as to
1001 // where extern libraries might live, based on the
1002 // addl_lib_search_paths
1003 if sess.opts.cg.rpath {
1004 let sysroot = sess.sysroot();
1005 let target_triple = &sess.opts.target_triple;
1006 let mut get_install_prefix_lib_path = || {
1007 let install_prefix = option_env!("CFG_PREFIX").expect("CFG_PREFIX");
1008 let tlib = filesearch::relative_target_lib_path(sysroot, target_triple);
1009 let mut path = PathBuf::from(install_prefix);
1014 let mut rpath_config = RPathConfig {
1015 used_crates: sess.cstore.used_crates(LinkagePreference::RequireDynamic),
1016 out_filename: out_filename.to_path_buf(),
1017 has_rpath: sess.target.target.options.has_rpath,
1018 is_like_osx: sess.target.target.options.is_like_osx,
1019 linker_is_gnu: sess.target.target.options.linker_is_gnu,
1020 get_install_prefix_lib_path: &mut get_install_prefix_lib_path,
1022 cmd.args(&rpath::get_rpath_flags(&mut rpath_config));
1025 // Finally add all the linker arguments provided on the command line along
1026 // with any #[link_args] attributes found inside the crate
1027 if let Some(ref args) = sess.opts.cg.link_args {
1030 cmd.args(&sess.opts.cg.link_arg);
1031 cmd.args(&used_link_args);
1034 // # Native library linking
1036 // User-supplied library search paths (-L on the command line). These are
1037 // the same paths used to find Rust crates, so some of them may have been
1038 // added already by the previous crate linking code. This only allows them
1039 // to be found at compile time so it is still entirely up to outside
1040 // forces to make sure that library can be found at runtime.
1042 // Also note that the native libraries linked here are only the ones located
1043 // in the current crate. Upstream crates with native library dependencies
1044 // may have their native library pulled in above.
1045 fn add_local_native_libraries(cmd: &mut Linker, sess: &Session) {
1046 sess.target_filesearch(PathKind::All).for_each_lib_search_path(|path, k| {
1048 PathKind::Framework => { cmd.framework_path(path); }
1049 _ => { cmd.include_path(&fix_windows_verbatim_for_gcc(path)); }
1053 let relevant_libs = sess.cstore.used_libraries().into_iter().filter(|l| {
1054 relevant_lib(sess, l)
1057 let search_path = archive_search_paths(sess);
1058 for lib in relevant_libs {
1060 NativeLibraryKind::NativeUnknown => cmd.link_dylib(&lib.name.as_str()),
1061 NativeLibraryKind::NativeFramework => cmd.link_framework(&lib.name.as_str()),
1062 NativeLibraryKind::NativeStaticNobundle => cmd.link_staticlib(&lib.name.as_str()),
1063 NativeLibraryKind::NativeStatic => cmd.link_whole_staticlib(&lib.name.as_str(),
1069 // # Rust Crate linking
1071 // Rust crates are not considered at all when creating an rlib output. All
1072 // dependencies will be linked when producing the final output (instead of
1073 // the intermediate rlib version)
1074 fn add_upstream_rust_crates(cmd: &mut Linker,
1076 crate_type: config::CrateType,
1078 // All of the heavy lifting has previously been accomplished by the
1079 // dependency_format module of the compiler. This is just crawling the
1080 // output of that module, adding crates as necessary.
1082 // Linking to a rlib involves just passing it to the linker (the linker
1083 // will slurp up the object files inside), and linking to a dynamic library
1084 // involves just passing the right -l flag.
1086 let formats = sess.dependency_formats.borrow();
1087 let data = formats.get(&crate_type).unwrap();
1089 // Invoke get_used_crates to ensure that we get a topological sorting of
1091 let deps = sess.cstore.used_crates(LinkagePreference::RequireDynamic);
1093 let mut compiler_builtins = None;
1095 for &(cnum, _) in &deps {
1096 // We may not pass all crates through to the linker. Some crates may
1097 // appear statically in an existing dylib, meaning we'll pick up all the
1098 // symbols from the dylib.
1099 let src = sess.cstore.used_crate_source(cnum);
1100 match data[cnum.as_usize() - 1] {
1101 _ if sess.cstore.is_sanitizer_runtime(cnum) => {
1102 link_sanitizer_runtime(cmd, sess, tmpdir, cnum);
1104 // compiler-builtins are always placed last to ensure that they're
1105 // linked correctly.
1106 _ if sess.cstore.is_compiler_builtins(cnum) => {
1107 assert!(compiler_builtins.is_none());
1108 compiler_builtins = Some(cnum);
1110 Linkage::NotLinked |
1111 Linkage::IncludedFromDylib => {}
1112 Linkage::Static => {
1113 add_static_crate(cmd, sess, tmpdir, crate_type, cnum);
1115 Linkage::Dynamic => {
1116 add_dynamic_crate(cmd, sess, &src.dylib.unwrap().0)
1121 // compiler-builtins are always placed last to ensure that they're
1122 // linked correctly.
1123 // We must always link the `compiler_builtins` crate statically. Even if it
1124 // was already "included" in a dylib (e.g. `libstd` when `-C prefer-dynamic`
1126 if let Some(cnum) = compiler_builtins {
1127 add_static_crate(cmd, sess, tmpdir, crate_type, cnum);
1130 // Converts a library file-stem into a cc -l argument
1131 fn unlib<'a>(config: &config::Config, stem: &'a str) -> &'a str {
1132 if stem.starts_with("lib") && !config.target.options.is_like_windows {
1139 // We must link the sanitizer runtime using -Wl,--whole-archive but since
1140 // it's packed in a .rlib, it contains stuff that are not objects that will
1141 // make the linker error. So we must remove those bits from the .rlib before
1143 fn link_sanitizer_runtime(cmd: &mut Linker,
1147 let src = sess.cstore.used_crate_source(cnum);
1148 let cratepath = &src.rlib.unwrap().0;
1150 if sess.target.target.options.is_like_osx {
1151 // On Apple platforms, the sanitizer is always built as a dylib, and
1152 // LLVM will link to `@rpath/*.dylib`, so we need to specify an
1153 // rpath to the library as well (the rpath should be absolute, see
1154 // PR #41352 for details).
1156 // FIXME: Remove this logic into librustc_*san once Cargo supports it
1157 let rpath = cratepath.parent().unwrap();
1158 let rpath = rpath.to_str().expect("non-utf8 component in path");
1159 cmd.args(&["-Wl,-rpath".into(), "-Xlinker".into(), rpath.into()]);
1162 let dst = tmpdir.join(cratepath.file_name().unwrap());
1163 let cfg = archive_config(sess, &dst, Some(cratepath));
1164 let mut archive = ArchiveBuilder::new(cfg);
1165 archive.update_symbols();
1167 for f in archive.src_files() {
1168 if f.ends_with("bytecode.deflate") || f == METADATA_FILENAME {
1169 archive.remove_file(&f);
1176 cmd.link_whole_rlib(&dst);
1179 // Adds the static "rlib" versions of all crates to the command line.
1180 // There's a bit of magic which happens here specifically related to LTO and
1181 // dynamic libraries. Specifically:
1183 // * For LTO, we remove upstream object files.
1184 // * For dylibs we remove metadata and bytecode from upstream rlibs
1186 // When performing LTO, almost(*) all of the bytecode from the upstream
1187 // libraries has already been included in our object file output. As a
1188 // result we need to remove the object files in the upstream libraries so
1189 // the linker doesn't try to include them twice (or whine about duplicate
1190 // symbols). We must continue to include the rest of the rlib, however, as
1191 // it may contain static native libraries which must be linked in.
1193 // (*) Crates marked with `#![no_builtins]` don't participate in LTO and
1194 // their bytecode wasn't included. The object files in those libraries must
1195 // still be passed to the linker.
1197 // When making a dynamic library, linkers by default don't include any
1198 // object files in an archive if they're not necessary to resolve the link.
1199 // We basically want to convert the archive (rlib) to a dylib, though, so we
1200 // *do* want everything included in the output, regardless of whether the
1201 // linker thinks it's needed or not. As a result we must use the
1202 // --whole-archive option (or the platform equivalent). When using this
1203 // option the linker will fail if there are non-objects in the archive (such
1204 // as our own metadata and/or bytecode). All in all, for rlibs to be
1205 // entirely included in dylibs, we need to remove all non-object files.
1207 // Note, however, that if we're not doing LTO or we're not producing a dylib
1208 // (aka we're making an executable), we can just pass the rlib blindly to
1209 // the linker (fast) because it's fine if it's not actually included as
1210 // we're at the end of the dependency chain.
1211 fn add_static_crate(cmd: &mut Linker,
1214 crate_type: config::CrateType,
1216 let src = sess.cstore.used_crate_source(cnum);
1217 let cratepath = &src.rlib.unwrap().0;
1219 // See the comment above in `link_staticlib` and `link_rlib` for why if
1220 // there's a static library that's not relevant we skip all object
1222 let native_libs = sess.cstore.native_libraries(cnum);
1223 let skip_native = native_libs.iter().any(|lib| {
1224 lib.kind == NativeLibraryKind::NativeStatic && !relevant_lib(sess, lib)
1227 if !sess.lto() && crate_type != config::CrateTypeDylib && !skip_native {
1228 cmd.link_rlib(&fix_windows_verbatim_for_gcc(cratepath));
1232 let dst = tmpdir.join(cratepath.file_name().unwrap());
1233 let name = cratepath.file_name().unwrap().to_str().unwrap();
1234 let name = &name[3..name.len() - 5]; // chop off lib/.rlib
1236 time(sess.time_passes(), &format!("altering {}.rlib", name), || {
1237 let cfg = archive_config(sess, &dst, Some(cratepath));
1238 let mut archive = ArchiveBuilder::new(cfg);
1239 archive.update_symbols();
1241 let mut any_objects = false;
1242 for f in archive.src_files() {
1243 if f.ends_with("bytecode.deflate") || f == METADATA_FILENAME {
1244 archive.remove_file(&f);
1248 let canonical = f.replace("-", "_");
1249 let canonical_name = name.replace("-", "_");
1251 let is_rust_object =
1252 canonical.starts_with(&canonical_name) && {
1253 let num = &f[name.len()..f.len() - 2];
1254 num.len() > 0 && num[1..].parse::<u32>().is_ok()
1257 // If we've been requested to skip all native object files
1258 // (those not generated by the rust compiler) then we can skip
1259 // this file. See above for why we may want to do this.
1260 let skip_because_cfg_say_so = skip_native && !is_rust_object;
1262 // If we're performing LTO and this is a rust-generated object
1263 // file, then we don't need the object file as it's part of the
1264 // LTO module. Note that `#![no_builtins]` is excluded from LTO,
1265 // though, so we let that object file slide.
1266 let skip_because_lto = sess.lto() && is_rust_object &&
1267 !sess.cstore.is_no_builtins(cnum);
1269 if skip_because_cfg_say_so || skip_because_lto {
1270 archive.remove_file(&f);
1281 // If we're creating a dylib, then we need to include the
1282 // whole of each object in our archive into that artifact. This is
1283 // because a `dylib` can be reused as an intermediate artifact.
1285 // Note, though, that we don't want to include the whole of a
1286 // compiler-builtins crate (e.g. compiler-rt) because it'll get
1287 // repeatedly linked anyway.
1288 if crate_type == config::CrateTypeDylib &&
1289 !sess.cstore.is_compiler_builtins(cnum) {
1290 cmd.link_whole_rlib(&fix_windows_verbatim_for_gcc(&dst));
1292 cmd.link_rlib(&fix_windows_verbatim_for_gcc(&dst));
1297 // Same thing as above, but for dynamic crates instead of static crates.
1298 fn add_dynamic_crate(cmd: &mut Linker, sess: &Session, cratepath: &Path) {
1299 // If we're performing LTO, then it should have been previously required
1300 // that all upstream rust dependencies were available in an rlib format.
1301 assert!(!sess.lto());
1303 // Just need to tell the linker about where the library lives and
1305 let parent = cratepath.parent();
1306 if let Some(dir) = parent {
1307 cmd.include_path(&fix_windows_verbatim_for_gcc(dir));
1309 let filestem = cratepath.file_stem().unwrap().to_str().unwrap();
1310 cmd.link_rust_dylib(&unlib(&sess.target, filestem),
1311 parent.unwrap_or(Path::new("")));
1315 // Link in all of our upstream crates' native dependencies. Remember that
1316 // all of these upstream native dependencies are all non-static
1317 // dependencies. We've got two cases then:
1319 // 1. The upstream crate is an rlib. In this case we *must* link in the
1320 // native dependency because the rlib is just an archive.
1322 // 2. The upstream crate is a dylib. In order to use the dylib, we have to
1323 // have the dependency present on the system somewhere. Thus, we don't
1324 // gain a whole lot from not linking in the dynamic dependency to this
1327 // The use case for this is a little subtle. In theory the native
1328 // dependencies of a crate are purely an implementation detail of the crate
1329 // itself, but the problem arises with generic and inlined functions. If a
1330 // generic function calls a native function, then the generic function must
1331 // be instantiated in the target crate, meaning that the native symbol must
1332 // also be resolved in the target crate.
1333 fn add_upstream_native_libraries(cmd: &mut Linker, sess: &Session, crate_type: config::CrateType) {
1334 // Be sure to use a topological sorting of crates because there may be
1335 // interdependencies between native libraries. When passing -nodefaultlibs,
1336 // for example, almost all native libraries depend on libc, so we have to
1337 // make sure that's all the way at the right (liblibc is near the base of
1338 // the dependency chain).
1340 // This passes RequireStatic, but the actual requirement doesn't matter,
1341 // we're just getting an ordering of crate numbers, we're not worried about
1343 let formats = sess.dependency_formats.borrow();
1344 let data = formats.get(&crate_type).unwrap();
1346 let crates = sess.cstore.used_crates(LinkagePreference::RequireStatic);
1347 for (cnum, _) in crates {
1348 for lib in sess.cstore.native_libraries(cnum) {
1349 if !relevant_lib(sess, &lib) {
1353 NativeLibraryKind::NativeUnknown => cmd.link_dylib(&lib.name.as_str()),
1354 NativeLibraryKind::NativeFramework => cmd.link_framework(&lib.name.as_str()),
1355 NativeLibraryKind::NativeStaticNobundle => {
1356 // Link "static-nobundle" native libs only if the crate they originate from
1357 // is being linked statically to the current crate. If it's linked dynamically
1358 // or is an rlib already included via some other dylib crate, the symbols from
1359 // native libs will have already been included in that dylib.
1360 if data[cnum.as_usize() - 1] == Linkage::Static {
1361 cmd.link_staticlib(&lib.name.as_str())
1364 // ignore statically included native libraries here as we've
1365 // already included them when we included the rust library
1367 NativeLibraryKind::NativeStatic => {}
1373 fn relevant_lib(sess: &Session, lib: &NativeLibrary) -> bool {
1375 Some(ref cfg) => attr::cfg_matches(cfg, &sess.parse_sess, None),