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;
17 use session::config::NoDebugInfo;
18 use session::config::{OutputFilenames, Input, OutputType};
19 use session::filesearch;
20 use session::search_paths::PathKind;
22 use middle::cstore::{self, LinkMeta, NativeLibrary, LibSource};
23 use middle::cstore::{LinkagePreference, NativeLibraryKind};
24 use middle::dependency_format::Linkage;
26 use util::common::time;
27 use util::fs::fix_windows_verbatim_for_gcc;
28 use rustc::dep_graph::DepNode;
29 use rustc::hir::def_id::CrateNum;
30 use rustc::hir::svh::Svh;
31 use rustc_back::tempdir::TempDir;
32 use rustc_back::PanicStrategy;
33 use rustc_incremental::IncrementalHashesMap;
34 use context::get_reloc_model;
40 use std::ffi::OsString;
42 use std::io::{self, Read, Write};
44 use std::path::{Path, PathBuf};
45 use std::process::Command;
50 use syntax::symbol::Symbol;
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,
143 crate_name: Symbol::intern(name),
144 crate_hash: Svh::new(incremental_hashes_map[&DepNode::Krate].to_smaller_hash()),
150 // The third parameter is for an extra path to add to PATH for MSVC
151 // cross linkers for host toolchain DLL dependencies
152 pub fn get_linker(sess: &Session) -> (String, Command, Option<PathBuf>) {
153 if let Some(ref linker) = sess.opts.cg.linker {
154 (linker.clone(), Command::new(linker), None)
155 } else if sess.target.target.options.is_like_msvc {
156 let (cmd, host) = msvc::link_exe_cmd(sess);
157 ("link.exe".to_string(), cmd, host)
159 (sess.target.target.options.linker.clone(),
160 Command::new(&sess.target.target.options.linker), None)
164 pub fn get_ar_prog(sess: &Session) -> String {
165 sess.opts.cg.ar.clone().unwrap_or_else(|| {
166 sess.target.target.options.ar.clone()
170 fn command_path(sess: &Session, extra: Option<PathBuf>) -> OsString {
171 // The compiler's sysroot often has some bundled tools, so add it to the
172 // PATH for the child.
173 let mut new_path = sess.host_filesearch(PathKind::All)
174 .get_tools_search_paths();
175 if let Some(path) = env::var_os("PATH") {
176 new_path.extend(env::split_paths(&path));
178 new_path.extend(extra);
179 env::join_paths(new_path).unwrap()
182 pub fn remove(sess: &Session, path: &Path) {
183 match fs::remove_file(path) {
186 sess.err(&format!("failed to remove {}: {}",
193 /// Perform the linkage portion of the compilation phase. This will generate all
194 /// of the requested outputs for this compilation session.
195 pub fn link_binary(sess: &Session,
196 trans: &CrateTranslation,
197 outputs: &OutputFilenames,
198 crate_name: &str) -> Vec<PathBuf> {
199 let _task = sess.dep_graph.in_task(DepNode::LinkBinary);
201 let mut out_filenames = Vec::new();
202 for &crate_type in sess.crate_types.borrow().iter() {
203 // Ignore executable crates if we have -Z no-trans, as they will error.
204 if (sess.opts.debugging_opts.no_trans ||
205 !sess.opts.output_types.should_trans()) &&
206 crate_type == config::CrateTypeExecutable {
210 if invalid_output_for_target(sess, crate_type) {
211 bug!("invalid output type `{:?}` for target os `{}`",
212 crate_type, sess.opts.target_triple);
214 let mut out_files = link_binary_output(sess, trans, crate_type, outputs, crate_name);
215 out_filenames.append(&mut out_files);
218 // Remove the temporary object file and metadata if we aren't saving temps
219 if !sess.opts.cg.save_temps {
220 if sess.opts.output_types.should_trans() {
221 for obj in object_filenames(trans, outputs) {
225 remove(sess, &outputs.with_extension(METADATA_OBJ_NAME));
232 /// Returns default crate type for target
234 /// Default crate type is used when crate type isn't provided neither
235 /// through cmd line arguments nor through crate attributes
237 /// It is CrateTypeExecutable for all platforms but iOS as there is no
238 /// way to run iOS binaries anyway without jailbreaking and
239 /// interaction with Rust code through static library is the only
241 pub fn default_output_for_target(sess: &Session) -> config::CrateType {
242 if !sess.target.target.options.executables {
243 config::CrateTypeStaticlib
245 config::CrateTypeExecutable
249 /// Checks if target supports crate_type as output
250 pub fn invalid_output_for_target(sess: &Session,
251 crate_type: config::CrateType) -> bool {
252 match (sess.target.target.options.dynamic_linking,
253 sess.target.target.options.executables, crate_type) {
254 (false, _, config::CrateTypeCdylib) |
255 (false, _, config::CrateTypeProcMacro) |
256 (false, _, config::CrateTypeDylib) => true,
257 (_, false, config::CrateTypeExecutable) => true,
262 fn is_writeable(p: &Path) -> bool {
265 Ok(m) => !m.permissions().readonly()
269 fn filename_for_metadata(sess: &Session, crate_name: &str, outputs: &OutputFilenames) -> PathBuf {
270 let out_filename = outputs.single_output_file.clone()
273 .join(&format!("lib{}{}.rmeta", crate_name, sess.opts.cg.extra_filename)));
274 check_file_is_writeable(&out_filename, sess);
278 pub fn filename_for_input(sess: &Session,
279 crate_type: config::CrateType,
281 outputs: &OutputFilenames) -> PathBuf {
282 let libname = format!("{}{}", crate_name, sess.opts.cg.extra_filename);
285 config::CrateTypeRlib => {
286 outputs.out_directory.join(&format!("lib{}.rlib", libname))
288 config::CrateTypeCdylib |
289 config::CrateTypeProcMacro |
290 config::CrateTypeDylib => {
291 let (prefix, suffix) = (&sess.target.target.options.dll_prefix,
292 &sess.target.target.options.dll_suffix);
293 outputs.out_directory.join(&format!("{}{}{}", prefix, libname,
296 config::CrateTypeStaticlib => {
297 let (prefix, suffix) = (&sess.target.target.options.staticlib_prefix,
298 &sess.target.target.options.staticlib_suffix);
299 outputs.out_directory.join(&format!("{}{}{}", prefix, libname,
302 config::CrateTypeExecutable => {
303 let suffix = &sess.target.target.options.exe_suffix;
304 let out_filename = outputs.path(OutputType::Exe);
305 if suffix.is_empty() {
306 out_filename.to_path_buf()
308 out_filename.with_extension(&suffix[1..])
314 pub fn each_linked_rlib(sess: &Session,
315 f: &mut FnMut(CrateNum, &Path)) {
316 let crates = sess.cstore.used_crates(LinkagePreference::RequireStatic).into_iter();
317 let fmts = sess.dependency_formats.borrow();
318 let fmts = fmts.get(&config::CrateTypeExecutable)
319 .or_else(|| fmts.get(&config::CrateTypeStaticlib))
320 .or_else(|| fmts.get(&config::CrateTypeCdylib))
321 .or_else(|| fmts.get(&config::CrateTypeProcMacro));
322 let fmts = fmts.unwrap_or_else(|| {
323 bug!("could not find formats for rlibs");
325 for (cnum, path) in crates {
326 match fmts[cnum.as_usize() - 1] {
327 Linkage::NotLinked | Linkage::IncludedFromDylib => continue,
330 let name = sess.cstore.crate_name(cnum).clone();
331 let path = match path {
332 LibSource::Some(p) => p,
333 LibSource::MetadataOnly => {
334 sess.fatal(&format!("could not find rlib for: `{}`, found rmeta (metadata) file",
338 sess.fatal(&format!("could not find rlib for: `{}`", name));
345 fn out_filename(sess: &Session,
346 crate_type: config::CrateType,
347 outputs: &OutputFilenames,
350 let default_filename = filename_for_input(sess, crate_type, crate_name, outputs);
351 let out_filename = outputs.outputs.get(&OutputType::Exe)
352 .and_then(|s| s.to_owned())
353 .or_else(|| outputs.single_output_file.clone())
354 .unwrap_or(default_filename);
356 check_file_is_writeable(&out_filename, sess);
361 // Make sure files are writeable. Mac, FreeBSD, and Windows system linkers
362 // check this already -- however, the Linux linker will happily overwrite a
363 // read-only file. We should be consistent.
364 fn check_file_is_writeable(file: &Path, sess: &Session) {
365 if !is_writeable(file) {
366 sess.fatal(&format!("output file {} is not writeable -- check its \
367 permissions", file.display()));
371 fn link_binary_output(sess: &Session,
372 trans: &CrateTranslation,
373 crate_type: config::CrateType,
374 outputs: &OutputFilenames,
375 crate_name: &str) -> Vec<PathBuf> {
376 let objects = object_filenames(trans, outputs);
378 for file in &objects {
379 check_file_is_writeable(file, sess);
382 let tmpdir = match TempDir::new("rustc") {
383 Ok(tmpdir) => tmpdir,
384 Err(err) => sess.fatal(&format!("couldn't create a temp dir: {}", err)),
387 let mut out_filenames = vec![];
389 if outputs.outputs.contains_key(&OutputType::Metadata) {
390 let out_filename = filename_for_metadata(sess, crate_name, outputs);
391 emit_metadata(sess, trans, &out_filename);
392 out_filenames.push(out_filename);
395 if outputs.outputs.should_trans() {
396 let out_filename = out_filename(sess, crate_type, outputs, crate_name);
398 config::CrateTypeRlib => {
399 link_rlib(sess, Some(trans), &objects, &out_filename,
400 tmpdir.path()).build();
402 config::CrateTypeStaticlib => {
403 link_staticlib(sess, &objects, &out_filename, tmpdir.path());
406 link_natively(sess, crate_type, &objects, &out_filename, trans,
407 outputs, tmpdir.path());
410 out_filenames.push(out_filename);
416 fn object_filenames(trans: &CrateTranslation,
417 outputs: &OutputFilenames)
419 trans.modules.iter().map(|module| {
420 outputs.temp_path(OutputType::Object, Some(&module.name))
424 fn archive_search_paths(sess: &Session) -> Vec<PathBuf> {
425 let mut search = Vec::new();
426 sess.target_filesearch(PathKind::Native).for_each_lib_search_path(|path, _| {
427 search.push(path.to_path_buf());
432 fn archive_config<'a>(sess: &'a Session,
434 input: Option<&Path>) -> ArchiveConfig<'a> {
437 dst: output.to_path_buf(),
438 src: input.map(|p| p.to_path_buf()),
439 lib_search_paths: archive_search_paths(sess),
440 ar_prog: get_ar_prog(sess),
441 command_path: command_path(sess, None),
445 fn emit_metadata<'a>(sess: &'a Session, trans: &CrateTranslation, out_filename: &Path) {
446 let result = fs::File::create(out_filename).and_then(|mut f| {
447 f.write_all(&trans.metadata.raw_data)
450 if let Err(e) = result {
451 sess.fatal(&format!("failed to write {}: {}", out_filename.display(), e));
457 // An rlib in its current incarnation is essentially a renamed .a file. The
458 // rlib primarily contains the object file of the crate, but it also contains
459 // all of the object files from native libraries. This is done by unzipping
460 // native libraries and inserting all of the contents into this archive.
461 fn link_rlib<'a>(sess: &'a Session,
462 trans: Option<&CrateTranslation>, // None == no metadata/bytecode
465 tmpdir: &Path) -> ArchiveBuilder<'a> {
466 info!("preparing rlib from {:?} to {:?}", objects, out_filename);
467 let mut ab = ArchiveBuilder::new(archive_config(sess, out_filename, None));
473 // Note that in this loop we are ignoring the value of `lib.cfg`. That is,
474 // we may not be configured to actually include a static library if we're
475 // adding it here. That's because later when we consume this rlib we'll
476 // decide whether we actually needed the static library or not.
478 // To do this "correctly" we'd need to keep track of which libraries added
479 // which object files to the archive. We don't do that here, however. The
480 // #[link(cfg(..))] feature is unstable, though, and only intended to get
481 // liblibc working. In that sense the check below just indicates that if
482 // there are any libraries we want to omit object files for at link time we
483 // just exclude all custom object files.
485 // Eventually if we want to stabilize or flesh out the #[link(cfg(..))]
486 // feature then we'll need to figure out how to record what objects were
487 // loaded from the libraries found here and then encode that into the
488 // metadata of the rlib we're generating somehow.
489 for lib in sess.cstore.used_libraries() {
491 NativeLibraryKind::NativeStatic => {}
492 NativeLibraryKind::NativeStaticNobundle |
493 NativeLibraryKind::NativeFramework |
494 NativeLibraryKind::NativeUnknown => continue,
496 ab.add_native_library(&lib.name.as_str());
499 // After adding all files to the archive, we need to update the
500 // symbol table of the archive.
503 // Note that it is important that we add all of our non-object "magical
504 // files" *after* all of the object files in the archive. The reason for
505 // this is as follows:
507 // * When performing LTO, this archive will be modified to remove
508 // objects from above. The reason for this is described below.
510 // * When the system linker looks at an archive, it will attempt to
511 // determine the architecture of the archive in order to see whether its
514 // The algorithm for this detection is: iterate over the files in the
515 // archive. Skip magical SYMDEF names. Interpret the first file as an
516 // object file. Read architecture from the object file.
518 // * As one can probably see, if "metadata" and "foo.bc" were placed
519 // before all of the objects, then the architecture of this archive would
520 // not be correctly inferred once 'foo.o' is removed.
522 // Basically, all this means is that this code should not move above the
526 // Instead of putting the metadata in an object file section, rlibs
527 // contain the metadata in a separate file. We use a temp directory
528 // here so concurrent builds in the same directory don't try to use
529 // the same filename for metadata (stomping over one another)
530 let metadata = tmpdir.join(sess.cstore.metadata_filename());
531 emit_metadata(sess, trans, &metadata);
532 ab.add_file(&metadata);
534 // For LTO purposes, the bytecode of this library is also inserted
535 // into the archive. If codegen_units > 1, we insert each of the
538 // Note that we make sure that the bytecode filename in the
539 // archive is never exactly 16 bytes long by adding a 16 byte
540 // extension to it. This is to work around a bug in LLDB that
541 // would cause it to crash if the name of a file in an archive
542 // was exactly 16 bytes.
543 let bc_filename = obj.with_extension("bc");
544 let bc_deflated_filename = tmpdir.join({
545 obj.with_extension("bytecode.deflate").file_name().unwrap()
548 let mut bc_data = Vec::new();
549 match fs::File::open(&bc_filename).and_then(|mut f| {
550 f.read_to_end(&mut bc_data)
553 Err(e) => sess.fatal(&format!("failed to read bytecode: {}",
557 let bc_data_deflated = flate::deflate_bytes(&bc_data);
559 let mut bc_file_deflated = match fs::File::create(&bc_deflated_filename) {
562 sess.fatal(&format!("failed to create compressed \
563 bytecode file: {}", e))
567 match write_rlib_bytecode_object_v1(&mut bc_file_deflated,
571 sess.fatal(&format!("failed to write compressed \
576 ab.add_file(&bc_deflated_filename);
578 // See the bottom of back::write::run_passes for an explanation
579 // of when we do and don't keep .#module-name#.bc files around.
580 let user_wants_numbered_bitcode =
581 sess.opts.output_types.contains_key(&OutputType::Bitcode) &&
582 sess.opts.cg.codegen_units > 1;
583 if !sess.opts.cg.save_temps && !user_wants_numbered_bitcode {
584 remove(sess, &bc_filename);
588 // After adding all files to the archive, we need to update the
589 // symbol table of the archive. This currently dies on macOS (see
590 // #11162), and isn't necessary there anyway
591 if !sess.target.target.options.is_like_osx {
602 fn write_rlib_bytecode_object_v1(writer: &mut Write,
603 bc_data_deflated: &[u8]) -> io::Result<()> {
604 let bc_data_deflated_size: u64 = bc_data_deflated.len() as u64;
606 writer.write_all(RLIB_BYTECODE_OBJECT_MAGIC)?;
607 writer.write_all(&[1, 0, 0, 0])?;
609 (bc_data_deflated_size >> 0) as u8,
610 (bc_data_deflated_size >> 8) as u8,
611 (bc_data_deflated_size >> 16) as u8,
612 (bc_data_deflated_size >> 24) as u8,
613 (bc_data_deflated_size >> 32) as u8,
614 (bc_data_deflated_size >> 40) as u8,
615 (bc_data_deflated_size >> 48) as u8,
616 (bc_data_deflated_size >> 56) as u8,
618 writer.write_all(&bc_data_deflated)?;
620 let number_of_bytes_written_so_far =
621 RLIB_BYTECODE_OBJECT_MAGIC.len() + // magic id
622 mem::size_of_val(&RLIB_BYTECODE_OBJECT_VERSION) + // version
623 mem::size_of_val(&bc_data_deflated_size) + // data size field
624 bc_data_deflated_size as usize; // actual data
626 // If the number of bytes written to the object so far is odd, add a
627 // padding byte to make it even. This works around a crash bug in LLDB
628 // (see issue #15950)
629 if number_of_bytes_written_so_far % 2 == 1 {
630 writer.write_all(&[0])?;
636 // Create a static archive
638 // This is essentially the same thing as an rlib, but it also involves adding
639 // all of the upstream crates' objects into the archive. This will slurp in
640 // all of the native libraries of upstream dependencies as well.
642 // Additionally, there's no way for us to link dynamic libraries, so we warn
643 // about all dynamic library dependencies that they're not linked in.
645 // There's no need to include metadata in a static archive, so ensure to not
646 // link in the metadata object file (and also don't prepare the archive with a
648 fn link_staticlib(sess: &Session, objects: &[PathBuf], out_filename: &Path,
650 let mut ab = link_rlib(sess, None, objects, out_filename, tempdir);
651 let mut all_native_libs = vec![];
653 each_linked_rlib(sess, &mut |cnum, path| {
654 let name = sess.cstore.crate_name(cnum);
655 let native_libs = sess.cstore.native_libraries(cnum);
657 // Here when we include the rlib into our staticlib we need to make a
658 // decision whether to include the extra object files along the way.
659 // These extra object files come from statically included native
660 // libraries, but they may be cfg'd away with #[link(cfg(..))].
662 // This unstable feature, though, only needs liblibc to work. The only
663 // use case there is where musl is statically included in liblibc.rlib,
664 // so if we don't want the included version we just need to skip it. As
665 // a result the logic here is that if *any* linked library is cfg'd away
666 // we just skip all object files.
668 // Clearly this is not sufficient for a general purpose feature, and
669 // we'd want to read from the library's metadata to determine which
670 // object files come from where and selectively skip them.
671 let skip_object_files = native_libs.iter().any(|lib| {
672 lib.kind == NativeLibraryKind::NativeStatic && !relevant_lib(sess, lib)
674 ab.add_rlib(path, &name.as_str(), sess.lto(), skip_object_files).unwrap();
676 all_native_libs.extend(sess.cstore.native_libraries(cnum));
682 if !all_native_libs.is_empty() {
683 sess.note_without_error("link against the following native artifacts when linking against \
684 this static library");
685 sess.note_without_error("the order and any duplication can be significant on some \
686 platforms, and so may need to be preserved");
689 for lib in all_native_libs.iter().filter(|l| relevant_lib(sess, l)) {
690 let name = match lib.kind {
691 NativeLibraryKind::NativeStaticNobundle |
692 NativeLibraryKind::NativeUnknown => "library",
693 NativeLibraryKind::NativeFramework => "framework",
694 // These are included, no need to print them
695 NativeLibraryKind::NativeStatic => continue,
697 sess.note_without_error(&format!("{}: {}", name, lib.name));
701 // Create a dynamic library or executable
703 // This will invoke the system linker/cc to create the resulting file. This
704 // links to all upstream files as well.
705 fn link_natively(sess: &Session,
706 crate_type: config::CrateType,
709 trans: &CrateTranslation,
710 outputs: &OutputFilenames,
712 info!("preparing {:?} from {:?} to {:?}", crate_type, objects, out_filename);
713 let flavor = sess.linker_flavor();
715 // The invocations of cc share some flags across platforms
716 let (pname, mut cmd, extra) = get_linker(sess);
717 cmd.env("PATH", command_path(sess, extra));
719 let root = sess.target_filesearch(PathKind::Native).get_lib_path();
720 if let Some(args) = sess.target.target.options.pre_link_args.get(&flavor) {
724 let pre_link_objects = if crate_type == config::CrateTypeExecutable {
725 &sess.target.target.options.pre_link_objects_exe
727 &sess.target.target.options.pre_link_objects_dll
729 for obj in pre_link_objects {
730 cmd.arg(root.join(obj));
733 if sess.target.target.options.is_like_emscripten {
735 cmd.arg(if sess.panic_strategy() == PanicStrategy::Abort {
736 "DISABLE_EXCEPTION_CATCHING=1"
738 "DISABLE_EXCEPTION_CATCHING=0"
743 let mut linker = trans.linker_info.to_linker(cmd, &sess);
744 link_args(&mut *linker, sess, crate_type, tmpdir,
745 objects, out_filename, outputs, trans);
746 cmd = linker.finalize();
748 if let Some(args) = sess.target.target.options.late_link_args.get(&flavor) {
751 for obj in &sess.target.target.options.post_link_objects {
752 cmd.arg(root.join(obj));
754 if let Some(args) = sess.target.target.options.post_link_args.get(&flavor) {
758 if sess.opts.debugging_opts.print_link_args {
759 println!("{:?}", &cmd);
762 // May have not found libraries in the right formats.
763 sess.abort_if_errors();
765 // Invoke the system linker
767 // Note that there's a terribly awful hack that really shouldn't be present
768 // in any compiler. Here an environment variable is supported to
769 // automatically retry the linker invocation if the linker looks like it
772 // Gee that seems odd, normally segfaults are things we want to know about!
773 // Unfortunately though in rust-lang/rust#38878 we're experiencing the
774 // linker segfaulting on Travis quite a bit which is causing quite a bit of
775 // pain to land PRs when they spuriously fail due to a segfault.
777 // The issue #38878 has some more debugging information on it as well, but
778 // this unfortunately looks like it's just a race condition in macOS's linker
779 // with some thread pool working in the background. It seems that no one
780 // currently knows a fix for this so in the meantime we're left with this...
782 let retry_on_segfault = env::var("RUSTC_RETRY_LINKER_ON_SEGFAULT").is_ok();
787 prog = time(sess.time_passes(), "running linker", || cmd.output());
788 if !retry_on_segfault || i > 3 {
791 let output = match prog {
792 Ok(ref output) => output,
795 if output.status.success() {
798 let mut out = output.stderr.clone();
799 out.extend(&output.stdout);
800 let out = String::from_utf8_lossy(&out);
801 let msg = "clang: error: unable to execute command: \
802 Segmentation fault: 11";
803 if !out.contains(msg) {
807 sess.struct_warn("looks like the linker segfaulted when we tried to \
808 call it, automatically retrying again")
809 .note(&format!("{:?}", cmd))
816 fn escape_string(s: &[u8]) -> String {
817 str::from_utf8(s).map(|s| s.to_owned())
818 .unwrap_or_else(|_| {
819 let mut x = "Non-UTF-8 output: ".to_string();
821 .flat_map(|&b| ascii::escape_default(b))
822 .map(|b| char::from_u32(b as u32).unwrap()));
826 if !prog.status.success() {
827 let mut output = prog.stderr.clone();
828 output.extend_from_slice(&prog.stdout);
829 sess.struct_err(&format!("linking with `{}` failed: {}",
832 .note(&format!("{:?}", &cmd))
833 .note(&escape_string(&output))
835 sess.abort_if_errors();
837 info!("linker stderr:\n{}", escape_string(&prog.stderr));
838 info!("linker stdout:\n{}", escape_string(&prog.stdout));
841 sess.struct_err(&format!("could not exec the linker `{}`: {}", pname, e))
842 .note(&format!("{:?}", &cmd))
844 if sess.target.target.options.is_like_msvc && e.kind() == io::ErrorKind::NotFound {
845 sess.note_without_error("the msvc targets depend on the msvc linker \
846 but `link.exe` was not found");
847 sess.note_without_error("please ensure that VS 2013 or VS 2015 was installed \
848 with the Visual C++ option");
850 sess.abort_if_errors();
855 // On macOS, debuggers need this utility to get run to do some munging of
857 if sess.target.target.options.is_like_osx && sess.opts.debuginfo != NoDebugInfo {
858 match Command::new("dsymutil").arg(out_filename).output() {
860 Err(e) => sess.fatal(&format!("failed to run dsymutil: {}", e)),
865 fn link_args(cmd: &mut Linker,
867 crate_type: config::CrateType,
871 outputs: &OutputFilenames,
872 trans: &CrateTranslation) {
874 // The default library location, we need this to find the runtime.
875 // The location of crates will be determined as needed.
876 let lib_path = sess.target_filesearch(PathKind::All).get_lib_path();
879 let t = &sess.target.target;
881 cmd.include_path(&fix_windows_verbatim_for_gcc(&lib_path));
885 cmd.output_filename(out_filename);
887 if crate_type == config::CrateTypeExecutable &&
888 sess.target.target.options.is_like_windows {
889 if let Some(ref s) = trans.windows_subsystem {
894 // If we're building a dynamic library then some platforms need to make sure
895 // that all symbols are exported correctly from the dynamic library.
896 if crate_type != config::CrateTypeExecutable ||
897 sess.target.target.options.is_like_emscripten {
898 cmd.export_symbols(tmpdir, crate_type);
901 // When linking a dynamic library, we put the metadata into a section of the
902 // executable. This metadata is in a separate object file from the main
903 // object file, so we link that in here.
904 if crate_type == config::CrateTypeDylib ||
905 crate_type == config::CrateTypeProcMacro {
906 cmd.add_object(&outputs.with_extension(METADATA_OBJ_NAME));
909 // Try to strip as much out of the generated object by removing unused
910 // sections if possible. See more comments in linker.rs
911 if !sess.opts.cg.link_dead_code {
912 let keep_metadata = crate_type == config::CrateTypeDylib;
913 cmd.gc_sections(keep_metadata);
916 let used_link_args = sess.cstore.used_link_args();
918 if crate_type == config::CrateTypeExecutable &&
919 t.options.position_independent_executables {
920 let empty_vec = Vec::new();
921 let args = sess.opts.cg.link_args.as_ref().unwrap_or(&empty_vec);
922 let more_args = &sess.opts.cg.link_arg;
923 let mut args = args.iter().chain(more_args.iter()).chain(used_link_args.iter());
925 if get_reloc_model(sess) == llvm::RelocMode::PIC
926 && !args.any(|x| *x == "-static") {
927 cmd.position_independent_executable();
931 // Pass optimization flags down to the linker.
934 // Pass debuginfo flags down to the linker.
937 // We want to prevent the compiler from accidentally leaking in any system
938 // libraries, so we explicitly ask gcc to not link to any libraries by
939 // default. Note that this does not happen for windows because windows pulls
940 // in some large number of libraries and I couldn't quite figure out which
942 if t.options.no_default_libraries {
943 cmd.no_default_libraries();
946 // Take careful note of the ordering of the arguments we pass to the linker
947 // here. Linkers will assume that things on the left depend on things to the
948 // right. Things on the right cannot depend on things on the left. This is
949 // all formally implemented in terms of resolving symbols (libs on the right
950 // resolve unknown symbols of libs on the left, but not vice versa).
952 // For this reason, we have organized the arguments we pass to the linker as
955 // 1. The local object that LLVM just generated
956 // 2. Local native libraries
957 // 3. Upstream rust libraries
958 // 4. Upstream native libraries
960 // The rationale behind this ordering is that those items lower down in the
961 // list can't depend on items higher up in the list. For example nothing can
962 // depend on what we just generated (e.g. that'd be a circular dependency).
963 // Upstream rust libraries are not allowed to depend on our local native
964 // libraries as that would violate the structure of the DAG, in that
965 // scenario they are required to link to them as well in a shared fashion.
967 // Note that upstream rust libraries may contain native dependencies as
968 // well, but they also can't depend on what we just started to add to the
969 // link line. And finally upstream native libraries can't depend on anything
970 // in this DAG so far because they're only dylibs and dylibs can only depend
971 // on other dylibs (e.g. other native deps).
972 add_local_native_libraries(cmd, sess);
973 add_upstream_rust_crates(cmd, sess, crate_type, tmpdir);
974 add_upstream_native_libraries(cmd, sess, crate_type);
976 // # Telling the linker what we're doing
978 if crate_type != config::CrateTypeExecutable {
979 cmd.build_dylib(out_filename);
982 // FIXME (#2397): At some point we want to rpath our guesses as to
983 // where extern libraries might live, based on the
984 // addl_lib_search_paths
985 if sess.opts.cg.rpath {
986 let sysroot = sess.sysroot();
987 let target_triple = &sess.opts.target_triple;
988 let mut get_install_prefix_lib_path = || {
989 let install_prefix = option_env!("CFG_PREFIX").expect("CFG_PREFIX");
990 let tlib = filesearch::relative_target_lib_path(sysroot, target_triple);
991 let mut path = PathBuf::from(install_prefix);
996 let mut rpath_config = RPathConfig {
997 used_crates: sess.cstore.used_crates(LinkagePreference::RequireDynamic),
998 out_filename: out_filename.to_path_buf(),
999 has_rpath: sess.target.target.options.has_rpath,
1000 is_like_osx: sess.target.target.options.is_like_osx,
1001 linker_is_gnu: sess.target.target.options.linker_is_gnu,
1002 get_install_prefix_lib_path: &mut get_install_prefix_lib_path,
1004 cmd.args(&rpath::get_rpath_flags(&mut rpath_config));
1007 // Finally add all the linker arguments provided on the command line along
1008 // with any #[link_args] attributes found inside the crate
1009 if let Some(ref args) = sess.opts.cg.link_args {
1012 cmd.args(&sess.opts.cg.link_arg);
1013 cmd.args(&used_link_args);
1016 // # Native library linking
1018 // User-supplied library search paths (-L on the command line). These are
1019 // the same paths used to find Rust crates, so some of them may have been
1020 // added already by the previous crate linking code. This only allows them
1021 // to be found at compile time so it is still entirely up to outside
1022 // forces to make sure that library can be found at runtime.
1024 // Also note that the native libraries linked here are only the ones located
1025 // in the current crate. Upstream crates with native library dependencies
1026 // may have their native library pulled in above.
1027 fn add_local_native_libraries(cmd: &mut Linker, sess: &Session) {
1028 sess.target_filesearch(PathKind::All).for_each_lib_search_path(|path, k| {
1030 PathKind::Framework => { cmd.framework_path(path); }
1031 _ => { cmd.include_path(&fix_windows_verbatim_for_gcc(path)); }
1035 let relevant_libs = sess.cstore.used_libraries().into_iter().filter(|l| {
1036 relevant_lib(sess, l)
1039 let search_path = archive_search_paths(sess);
1040 for lib in relevant_libs {
1042 NativeLibraryKind::NativeUnknown => cmd.link_dylib(&lib.name.as_str()),
1043 NativeLibraryKind::NativeFramework => cmd.link_framework(&lib.name.as_str()),
1044 NativeLibraryKind::NativeStaticNobundle => cmd.link_staticlib(&lib.name.as_str()),
1045 NativeLibraryKind::NativeStatic => cmd.link_whole_staticlib(&lib.name.as_str(),
1051 // # Rust Crate linking
1053 // Rust crates are not considered at all when creating an rlib output. All
1054 // dependencies will be linked when producing the final output (instead of
1055 // the intermediate rlib version)
1056 fn add_upstream_rust_crates(cmd: &mut Linker,
1058 crate_type: config::CrateType,
1060 // All of the heavy lifting has previously been accomplished by the
1061 // dependency_format module of the compiler. This is just crawling the
1062 // output of that module, adding crates as necessary.
1064 // Linking to a rlib involves just passing it to the linker (the linker
1065 // will slurp up the object files inside), and linking to a dynamic library
1066 // involves just passing the right -l flag.
1068 let formats = sess.dependency_formats.borrow();
1069 let data = formats.get(&crate_type).unwrap();
1071 // Invoke get_used_crates to ensure that we get a topological sorting of
1073 let deps = sess.cstore.used_crates(LinkagePreference::RequireDynamic);
1075 let mut compiler_builtins = None;
1077 for &(cnum, _) in &deps {
1078 // We may not pass all crates through to the linker. Some crates may
1079 // appear statically in an existing dylib, meaning we'll pick up all the
1080 // symbols from the dylib.
1081 let src = sess.cstore.used_crate_source(cnum);
1082 match data[cnum.as_usize() - 1] {
1083 _ if sess.cstore.is_sanitizer_runtime(cnum) => {
1084 link_sanitizer_runtime(cmd, sess, tmpdir, cnum);
1086 // compiler-builtins are always placed last to ensure that they're
1087 // linked correctly.
1088 _ if sess.cstore.is_compiler_builtins(cnum) => {
1089 assert!(compiler_builtins.is_none());
1090 compiler_builtins = Some(cnum);
1092 Linkage::NotLinked |
1093 Linkage::IncludedFromDylib => {}
1094 Linkage::Static => {
1095 add_static_crate(cmd, sess, tmpdir, crate_type, cnum);
1097 Linkage::Dynamic => {
1098 add_dynamic_crate(cmd, sess, &src.dylib.unwrap().0)
1103 // compiler-builtins are always placed last to ensure that they're
1104 // linked correctly.
1105 // We must always link the `compiler_builtins` crate statically. Even if it
1106 // was already "included" in a dylib (e.g. `libstd` when `-C prefer-dynamic`
1108 if let Some(cnum) = compiler_builtins {
1109 add_static_crate(cmd, sess, tmpdir, crate_type, cnum);
1112 // Converts a library file-stem into a cc -l argument
1113 fn unlib<'a>(config: &config::Config, stem: &'a str) -> &'a str {
1114 if stem.starts_with("lib") && !config.target.options.is_like_windows {
1121 // We must link the sanitizer runtime using -Wl,--whole-archive but since
1122 // it's packed in a .rlib, it contains stuff that are not objects that will
1123 // make the linker error. So we must remove those bits from the .rlib before
1125 fn link_sanitizer_runtime(cmd: &mut Linker,
1129 let src = sess.cstore.used_crate_source(cnum);
1130 let cratepath = &src.rlib.unwrap().0;
1131 let dst = tmpdir.join(cratepath.file_name().unwrap());
1132 let cfg = archive_config(sess, &dst, Some(cratepath));
1133 let mut archive = ArchiveBuilder::new(cfg);
1134 archive.update_symbols();
1136 for f in archive.src_files() {
1137 if f.ends_with("bytecode.deflate") ||
1138 f == sess.cstore.metadata_filename() {
1139 archive.remove_file(&f);
1146 cmd.link_whole_rlib(&dst);
1149 // Adds the static "rlib" versions of all crates to the command line.
1150 // There's a bit of magic which happens here specifically related to LTO and
1151 // dynamic libraries. Specifically:
1153 // * For LTO, we remove upstream object files.
1154 // * For dylibs we remove metadata and bytecode from upstream rlibs
1156 // When performing LTO, almost(*) all of the bytecode from the upstream
1157 // libraries has already been included in our object file output. As a
1158 // result we need to remove the object files in the upstream libraries so
1159 // the linker doesn't try to include them twice (or whine about duplicate
1160 // symbols). We must continue to include the rest of the rlib, however, as
1161 // it may contain static native libraries which must be linked in.
1163 // (*) Crates marked with `#![no_builtins]` don't participate in LTO and
1164 // their bytecode wasn't included. The object files in those libraries must
1165 // still be passed to the linker.
1167 // When making a dynamic library, linkers by default don't include any
1168 // object files in an archive if they're not necessary to resolve the link.
1169 // We basically want to convert the archive (rlib) to a dylib, though, so we
1170 // *do* want everything included in the output, regardless of whether the
1171 // linker thinks it's needed or not. As a result we must use the
1172 // --whole-archive option (or the platform equivalent). When using this
1173 // option the linker will fail if there are non-objects in the archive (such
1174 // as our own metadata and/or bytecode). All in all, for rlibs to be
1175 // entirely included in dylibs, we need to remove all non-object files.
1177 // Note, however, that if we're not doing LTO or we're not producing a dylib
1178 // (aka we're making an executable), we can just pass the rlib blindly to
1179 // the linker (fast) because it's fine if it's not actually included as
1180 // we're at the end of the dependency chain.
1181 fn add_static_crate(cmd: &mut Linker,
1184 crate_type: config::CrateType,
1186 let src = sess.cstore.used_crate_source(cnum);
1187 let cratepath = &src.rlib.unwrap().0;
1189 // See the comment above in `link_staticlib` and `link_rlib` for why if
1190 // there's a static library that's not relevant we skip all object
1192 let native_libs = sess.cstore.native_libraries(cnum);
1193 let skip_native = native_libs.iter().any(|lib| {
1194 lib.kind == NativeLibraryKind::NativeStatic && !relevant_lib(sess, lib)
1197 if !sess.lto() && crate_type != config::CrateTypeDylib && !skip_native {
1198 cmd.link_rlib(&fix_windows_verbatim_for_gcc(cratepath));
1202 let dst = tmpdir.join(cratepath.file_name().unwrap());
1203 let name = cratepath.file_name().unwrap().to_str().unwrap();
1204 let name = &name[3..name.len() - 5]; // chop off lib/.rlib
1206 time(sess.time_passes(), &format!("altering {}.rlib", name), || {
1207 let cfg = archive_config(sess, &dst, Some(cratepath));
1208 let mut archive = ArchiveBuilder::new(cfg);
1209 archive.update_symbols();
1211 let mut any_objects = false;
1212 for f in archive.src_files() {
1213 if f.ends_with("bytecode.deflate") ||
1214 f == sess.cstore.metadata_filename() {
1215 archive.remove_file(&f);
1219 let canonical = f.replace("-", "_");
1220 let canonical_name = name.replace("-", "_");
1222 let is_rust_object =
1223 canonical.starts_with(&canonical_name) && {
1224 let num = &f[name.len()..f.len() - 2];
1225 num.len() > 0 && num[1..].parse::<u32>().is_ok()
1228 // If we've been requested to skip all native object files
1229 // (those not generated by the rust compiler) then we can skip
1230 // this file. See above for why we may want to do this.
1231 let skip_because_cfg_say_so = skip_native && !is_rust_object;
1233 // If we're performing LTO and this is a rust-generated object
1234 // file, then we don't need the object file as it's part of the
1235 // LTO module. Note that `#![no_builtins]` is excluded from LTO,
1236 // though, so we let that object file slide.
1237 let skip_because_lto = sess.lto() && is_rust_object &&
1238 !sess.cstore.is_no_builtins(cnum);
1240 if skip_because_cfg_say_so || skip_because_lto {
1241 archive.remove_file(&f);
1252 // If we're creating a dylib, then we need to include the
1253 // whole of each object in our archive into that artifact. This is
1254 // because a `dylib` can be reused as an intermediate artifact.
1256 // Note, though, that we don't want to include the whole of a
1257 // compiler-builtins crate (e.g. compiler-rt) because it'll get
1258 // repeatedly linked anyway.
1259 if crate_type == config::CrateTypeDylib &&
1260 !sess.cstore.is_compiler_builtins(cnum) {
1261 cmd.link_whole_rlib(&fix_windows_verbatim_for_gcc(&dst));
1263 cmd.link_rlib(&fix_windows_verbatim_for_gcc(&dst));
1268 // Same thing as above, but for dynamic crates instead of static crates.
1269 fn add_dynamic_crate(cmd: &mut Linker, sess: &Session, cratepath: &Path) {
1270 // If we're performing LTO, then it should have been previously required
1271 // that all upstream rust dependencies were available in an rlib format.
1272 assert!(!sess.lto());
1274 // Just need to tell the linker about where the library lives and
1276 let parent = cratepath.parent();
1277 if let Some(dir) = parent {
1278 cmd.include_path(&fix_windows_verbatim_for_gcc(dir));
1280 let filestem = cratepath.file_stem().unwrap().to_str().unwrap();
1281 cmd.link_rust_dylib(&unlib(&sess.target, filestem),
1282 parent.unwrap_or(Path::new("")));
1286 // Link in all of our upstream crates' native dependencies. Remember that
1287 // all of these upstream native dependencies are all non-static
1288 // dependencies. We've got two cases then:
1290 // 1. The upstream crate is an rlib. In this case we *must* link in the
1291 // native dependency because the rlib is just an archive.
1293 // 2. The upstream crate is a dylib. In order to use the dylib, we have to
1294 // have the dependency present on the system somewhere. Thus, we don't
1295 // gain a whole lot from not linking in the dynamic dependency to this
1298 // The use case for this is a little subtle. In theory the native
1299 // dependencies of a crate are purely an implementation detail of the crate
1300 // itself, but the problem arises with generic and inlined functions. If a
1301 // generic function calls a native function, then the generic function must
1302 // be instantiated in the target crate, meaning that the native symbol must
1303 // also be resolved in the target crate.
1304 fn add_upstream_native_libraries(cmd: &mut Linker, sess: &Session, crate_type: config::CrateType) {
1305 // Be sure to use a topological sorting of crates because there may be
1306 // interdependencies between native libraries. When passing -nodefaultlibs,
1307 // for example, almost all native libraries depend on libc, so we have to
1308 // make sure that's all the way at the right (liblibc is near the base of
1309 // the dependency chain).
1311 // This passes RequireStatic, but the actual requirement doesn't matter,
1312 // we're just getting an ordering of crate numbers, we're not worried about
1314 let formats = sess.dependency_formats.borrow();
1315 let data = formats.get(&crate_type).unwrap();
1317 let crates = sess.cstore.used_crates(LinkagePreference::RequireStatic);
1318 for (cnum, _) in crates {
1319 for lib in sess.cstore.native_libraries(cnum) {
1320 if !relevant_lib(sess, &lib) {
1324 NativeLibraryKind::NativeUnknown => cmd.link_dylib(&lib.name.as_str()),
1325 NativeLibraryKind::NativeFramework => cmd.link_framework(&lib.name.as_str()),
1326 NativeLibraryKind::NativeStaticNobundle => {
1327 // Link "static-nobundle" native libs only if the crate they originate from
1328 // is being linked statically to the current crate. If it's linked dynamically
1329 // or is an rlib already included via some other dylib crate, the symbols from
1330 // native libs will have already been included in that dylib.
1331 if data[cnum.as_usize() - 1] == Linkage::Static {
1332 cmd.link_staticlib(&lib.name.as_str())
1335 // ignore statically included native libraries here as we've
1336 // already included them when we included the rust library
1338 NativeLibraryKind::NativeStatic => {}
1344 fn relevant_lib(sess: &Session, lib: &NativeLibrary) -> bool {
1346 Some(ref cfg) => attr::cfg_matches(cfg, &sess.parse_sess, None),