1 // Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 use super::archive::{ArchiveBuilder, ArchiveConfig};
12 use super::linker::Linker;
13 use super::rpath::RPathConfig;
15 use metadata::METADATA_FILENAME;
16 use rustc::session::config::{self, NoDebugInfo, OutputFilenames, Input, OutputType};
17 use rustc::session::filesearch;
18 use rustc::session::search_paths::PathKind;
19 use rustc::session::Session;
20 use rustc::middle::cstore::{self, LinkMeta, NativeLibrary, LibSource, LinkagePreference,
22 use rustc::middle::dependency_format::Linkage;
24 use rustc::util::common::time;
25 use rustc::util::fs::fix_windows_verbatim_for_gcc;
26 use rustc::dep_graph::{DepKind, DepNode};
27 use rustc::hir::def_id::CrateNum;
28 use rustc::hir::svh::Svh;
29 use rustc_back::tempdir::TempDir;
30 use rustc_back::PanicStrategy;
31 use rustc_incremental::IncrementalHashesMap;
32 use context::get_reloc_model;
38 use std::ffi::OsString;
40 use std::io::{self, Read, Write};
42 use std::path::{Path, PathBuf};
43 use std::process::Command;
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 {
137 let krate_dep_node = &DepNode::new_no_params(DepKind::Krate);
139 crate_hash: Svh::new(incremental_hashes_map[krate_dep_node].to_smaller_hash()),
145 // The third parameter is for env vars, used on windows to set up the
146 // path for MSVC to find its DLLs, and gcc to find its bundled
148 pub fn get_linker(sess: &Session) -> (String, Command, Vec<(OsString, OsString)>) {
149 let envs = vec![("PATH".into(), command_path(sess))];
151 if let Some(ref linker) = sess.opts.cg.linker {
152 (linker.clone(), Command::new(linker), envs)
153 } else if sess.target.target.options.is_like_msvc {
154 let (cmd, envs) = msvc_link_exe_cmd(sess);
155 ("link.exe".to_string(), cmd, envs)
157 let linker = &sess.target.target.options.linker;
158 (linker.clone(), Command::new(&linker), envs)
163 pub fn msvc_link_exe_cmd(sess: &Session) -> (Command, Vec<(OsString, OsString)>) {
164 use gcc::windows_registry;
166 let target = &sess.opts.target_triple;
167 let tool = windows_registry::find_tool(target, "link.exe");
169 if let Some(tool) = tool {
170 let envs = tool.env().to_vec();
171 (tool.to_command(), envs)
173 debug!("Failed to locate linker.");
174 (Command::new("link.exe"), vec![])
179 pub fn msvc_link_exe_cmd(_sess: &Session) -> (Command, Vec<(OsString, OsString)>) {
180 (Command::new("link.exe"), vec![])
183 pub fn get_ar_prog(sess: &Session) -> String {
184 sess.opts.cg.ar.clone().unwrap_or_else(|| {
185 sess.target.target.options.ar.clone()
189 fn command_path(sess: &Session) -> OsString {
190 // The compiler's sysroot often has some bundled tools, so add it to the
191 // PATH for the child.
192 let mut new_path = sess.host_filesearch(PathKind::All)
193 .get_tools_search_paths();
194 if let Some(path) = env::var_os("PATH") {
195 new_path.extend(env::split_paths(&path));
197 env::join_paths(new_path).unwrap()
200 pub fn remove(sess: &Session, path: &Path) {
201 match fs::remove_file(path) {
204 sess.err(&format!("failed to remove {}: {}",
211 /// Perform the linkage portion of the compilation phase. This will generate all
212 /// of the requested outputs for this compilation session.
213 pub fn link_binary(sess: &Session,
214 trans: &CrateTranslation,
215 outputs: &OutputFilenames,
216 crate_name: &str) -> Vec<PathBuf> {
217 let mut out_filenames = Vec::new();
218 for &crate_type in sess.crate_types.borrow().iter() {
219 // Ignore executable crates if we have -Z no-trans, as they will error.
220 if (sess.opts.debugging_opts.no_trans ||
221 !sess.opts.output_types.should_trans()) &&
222 crate_type == config::CrateTypeExecutable {
226 if invalid_output_for_target(sess, crate_type) {
227 bug!("invalid output type `{:?}` for target os `{}`",
228 crate_type, sess.opts.target_triple);
230 let mut out_files = link_binary_output(sess, trans, crate_type, outputs, crate_name);
231 out_filenames.append(&mut out_files);
234 // Remove the temporary object file and metadata if we aren't saving temps
235 if !sess.opts.cg.save_temps {
236 if sess.opts.output_types.should_trans() {
237 for obj in object_filenames(trans, outputs) {
241 remove(sess, &outputs.with_extension(METADATA_OBJ_NAME));
248 /// Returns default crate type for target
250 /// Default crate type is used when crate type isn't provided neither
251 /// through cmd line arguments nor through crate attributes
253 /// It is CrateTypeExecutable for all platforms but iOS as there is no
254 /// way to run iOS binaries anyway without jailbreaking and
255 /// interaction with Rust code through static library is the only
257 pub fn default_output_for_target(sess: &Session) -> config::CrateType {
258 if !sess.target.target.options.executables {
259 config::CrateTypeStaticlib
261 config::CrateTypeExecutable
265 /// Checks if target supports crate_type as output
266 pub fn invalid_output_for_target(sess: &Session,
267 crate_type: config::CrateType) -> bool {
268 match (sess.target.target.options.dynamic_linking,
269 sess.target.target.options.executables, crate_type) {
270 (false, _, config::CrateTypeCdylib) |
271 (false, _, config::CrateTypeProcMacro) |
272 (false, _, config::CrateTypeDylib) => true,
273 (_, false, config::CrateTypeExecutable) => true,
278 fn is_writeable(p: &Path) -> bool {
281 Ok(m) => !m.permissions().readonly()
285 fn filename_for_metadata(sess: &Session, crate_name: &str, outputs: &OutputFilenames) -> PathBuf {
286 let out_filename = outputs.single_output_file.clone()
289 .join(&format!("lib{}{}.rmeta", crate_name, sess.opts.cg.extra_filename)));
290 check_file_is_writeable(&out_filename, sess);
294 pub fn filename_for_input(sess: &Session,
295 crate_type: config::CrateType,
297 outputs: &OutputFilenames) -> PathBuf {
298 let libname = format!("{}{}", crate_name, sess.opts.cg.extra_filename);
301 config::CrateTypeRlib => {
302 outputs.out_directory.join(&format!("lib{}.rlib", libname))
304 config::CrateTypeCdylib |
305 config::CrateTypeProcMacro |
306 config::CrateTypeDylib => {
307 let (prefix, suffix) = (&sess.target.target.options.dll_prefix,
308 &sess.target.target.options.dll_suffix);
309 outputs.out_directory.join(&format!("{}{}{}", prefix, libname,
312 config::CrateTypeStaticlib => {
313 let (prefix, suffix) = (&sess.target.target.options.staticlib_prefix,
314 &sess.target.target.options.staticlib_suffix);
315 outputs.out_directory.join(&format!("{}{}{}", prefix, libname,
318 config::CrateTypeExecutable => {
319 let suffix = &sess.target.target.options.exe_suffix;
320 let out_filename = outputs.path(OutputType::Exe);
321 if suffix.is_empty() {
322 out_filename.to_path_buf()
324 out_filename.with_extension(&suffix[1..])
330 pub fn each_linked_rlib(sess: &Session,
331 f: &mut FnMut(CrateNum, &Path)) {
332 let crates = sess.cstore.used_crates(LinkagePreference::RequireStatic).into_iter();
333 let fmts = sess.dependency_formats.borrow();
334 let fmts = fmts.get(&config::CrateTypeExecutable)
335 .or_else(|| fmts.get(&config::CrateTypeStaticlib))
336 .or_else(|| fmts.get(&config::CrateTypeCdylib))
337 .or_else(|| fmts.get(&config::CrateTypeProcMacro));
338 let fmts = fmts.unwrap_or_else(|| {
339 bug!("could not find formats for rlibs");
341 for (cnum, path) in crates {
342 match fmts[cnum.as_usize() - 1] {
343 Linkage::NotLinked | Linkage::IncludedFromDylib => continue,
346 let name = sess.cstore.crate_name(cnum).clone();
347 let path = match path {
348 LibSource::Some(p) => p,
349 LibSource::MetadataOnly => {
350 sess.fatal(&format!("could not find rlib for: `{}`, found rmeta (metadata) file",
354 sess.fatal(&format!("could not find rlib for: `{}`", name));
361 fn out_filename(sess: &Session,
362 crate_type: config::CrateType,
363 outputs: &OutputFilenames,
366 let default_filename = filename_for_input(sess, crate_type, crate_name, outputs);
367 let out_filename = outputs.outputs.get(&OutputType::Exe)
368 .and_then(|s| s.to_owned())
369 .or_else(|| outputs.single_output_file.clone())
370 .unwrap_or(default_filename);
372 check_file_is_writeable(&out_filename, sess);
377 // Make sure files are writeable. Mac, FreeBSD, and Windows system linkers
378 // check this already -- however, the Linux linker will happily overwrite a
379 // read-only file. We should be consistent.
380 fn check_file_is_writeable(file: &Path, sess: &Session) {
381 if !is_writeable(file) {
382 sess.fatal(&format!("output file {} is not writeable -- check its \
383 permissions", file.display()));
387 fn link_binary_output(sess: &Session,
388 trans: &CrateTranslation,
389 crate_type: config::CrateType,
390 outputs: &OutputFilenames,
391 crate_name: &str) -> Vec<PathBuf> {
392 let objects = object_filenames(trans, outputs);
394 for file in &objects {
395 check_file_is_writeable(file, sess);
398 let tmpdir = match TempDir::new("rustc") {
399 Ok(tmpdir) => tmpdir,
400 Err(err) => sess.fatal(&format!("couldn't create a temp dir: {}", err)),
403 let mut out_filenames = vec![];
405 if outputs.outputs.contains_key(&OutputType::Metadata) {
406 let out_filename = filename_for_metadata(sess, crate_name, outputs);
407 emit_metadata(sess, trans, &out_filename);
408 out_filenames.push(out_filename);
411 if outputs.outputs.should_trans() {
412 let out_filename = out_filename(sess, crate_type, outputs, crate_name);
414 config::CrateTypeRlib => {
415 link_rlib(sess, Some(trans), &objects, &out_filename,
416 tmpdir.path()).build();
418 config::CrateTypeStaticlib => {
419 link_staticlib(sess, &objects, &out_filename, tmpdir.path());
422 link_natively(sess, crate_type, &objects, &out_filename, trans,
423 outputs, tmpdir.path());
426 out_filenames.push(out_filename);
432 fn object_filenames(trans: &CrateTranslation,
433 outputs: &OutputFilenames)
435 trans.modules.iter().map(|module| {
436 outputs.temp_path(OutputType::Object, Some(&module.name))
440 fn archive_search_paths(sess: &Session) -> Vec<PathBuf> {
441 let mut search = Vec::new();
442 sess.target_filesearch(PathKind::Native).for_each_lib_search_path(|path, _| {
443 search.push(path.to_path_buf());
448 fn archive_config<'a>(sess: &'a Session,
450 input: Option<&Path>) -> ArchiveConfig<'a> {
453 dst: output.to_path_buf(),
454 src: input.map(|p| p.to_path_buf()),
455 lib_search_paths: archive_search_paths(sess),
456 ar_prog: get_ar_prog(sess),
457 command_path: command_path(sess),
461 fn emit_metadata<'a>(sess: &'a Session, trans: &CrateTranslation, out_filename: &Path) {
462 let result = fs::File::create(out_filename).and_then(|mut f| {
463 f.write_all(&trans.metadata.raw_data)
466 if let Err(e) = result {
467 sess.fatal(&format!("failed to write {}: {}", out_filename.display(), e));
473 // An rlib in its current incarnation is essentially a renamed .a file. The
474 // rlib primarily contains the object file of the crate, but it also contains
475 // all of the object files from native libraries. This is done by unzipping
476 // native libraries and inserting all of the contents into this archive.
477 fn link_rlib<'a>(sess: &'a Session,
478 trans: Option<&CrateTranslation>, // None == no metadata/bytecode
481 tmpdir: &Path) -> ArchiveBuilder<'a> {
482 info!("preparing rlib from {:?} to {:?}", objects, out_filename);
483 let mut ab = ArchiveBuilder::new(archive_config(sess, out_filename, None));
489 // Note that in this loop we are ignoring the value of `lib.cfg`. That is,
490 // we may not be configured to actually include a static library if we're
491 // adding it here. That's because later when we consume this rlib we'll
492 // decide whether we actually needed the static library or not.
494 // To do this "correctly" we'd need to keep track of which libraries added
495 // which object files to the archive. We don't do that here, however. The
496 // #[link(cfg(..))] feature is unstable, though, and only intended to get
497 // liblibc working. In that sense the check below just indicates that if
498 // there are any libraries we want to omit object files for at link time we
499 // just exclude all custom object files.
501 // Eventually if we want to stabilize or flesh out the #[link(cfg(..))]
502 // feature then we'll need to figure out how to record what objects were
503 // loaded from the libraries found here and then encode that into the
504 // metadata of the rlib we're generating somehow.
505 for lib in sess.cstore.used_libraries() {
507 NativeLibraryKind::NativeStatic => {}
508 NativeLibraryKind::NativeStaticNobundle |
509 NativeLibraryKind::NativeFramework |
510 NativeLibraryKind::NativeUnknown => continue,
512 ab.add_native_library(&lib.name.as_str());
515 // After adding all files to the archive, we need to update the
516 // symbol table of the archive.
519 // Note that it is important that we add all of our non-object "magical
520 // files" *after* all of the object files in the archive. The reason for
521 // this is as follows:
523 // * When performing LTO, this archive will be modified to remove
524 // objects from above. The reason for this is described below.
526 // * When the system linker looks at an archive, it will attempt to
527 // determine the architecture of the archive in order to see whether its
530 // The algorithm for this detection is: iterate over the files in the
531 // archive. Skip magical SYMDEF names. Interpret the first file as an
532 // object file. Read architecture from the object file.
534 // * As one can probably see, if "metadata" and "foo.bc" were placed
535 // before all of the objects, then the architecture of this archive would
536 // not be correctly inferred once 'foo.o' is removed.
538 // Basically, all this means is that this code should not move above the
542 // Instead of putting the metadata in an object file section, rlibs
543 // contain the metadata in a separate file. We use a temp directory
544 // here so concurrent builds in the same directory don't try to use
545 // the same filename for metadata (stomping over one another)
546 let metadata = tmpdir.join(METADATA_FILENAME);
547 emit_metadata(sess, trans, &metadata);
548 ab.add_file(&metadata);
550 // For LTO purposes, the bytecode of this library is also inserted
551 // into the archive. If codegen_units > 1, we insert each of the
554 // Note that we make sure that the bytecode filename in the
555 // archive is never exactly 16 bytes long by adding a 16 byte
556 // extension to it. This is to work around a bug in LLDB that
557 // would cause it to crash if the name of a file in an archive
558 // was exactly 16 bytes.
559 let bc_filename = obj.with_extension("bc");
560 let bc_deflated_filename = tmpdir.join({
561 obj.with_extension("bytecode.deflate").file_name().unwrap()
564 let mut bc_data = Vec::new();
565 match fs::File::open(&bc_filename).and_then(|mut f| {
566 f.read_to_end(&mut bc_data)
569 Err(e) => sess.fatal(&format!("failed to read bytecode: {}",
573 let bc_data_deflated = flate::deflate_bytes(&bc_data);
575 let mut bc_file_deflated = match fs::File::create(&bc_deflated_filename) {
578 sess.fatal(&format!("failed to create compressed \
579 bytecode file: {}", e))
583 match write_rlib_bytecode_object_v1(&mut bc_file_deflated,
587 sess.fatal(&format!("failed to write compressed \
592 ab.add_file(&bc_deflated_filename);
594 // See the bottom of back::write::run_passes for an explanation
595 // of when we do and don't keep .#module-name#.bc files around.
596 let user_wants_numbered_bitcode =
597 sess.opts.output_types.contains_key(&OutputType::Bitcode) &&
598 sess.opts.cg.codegen_units > 1;
599 if !sess.opts.cg.save_temps && !user_wants_numbered_bitcode {
600 remove(sess, &bc_filename);
604 // After adding all files to the archive, we need to update the
605 // symbol table of the archive. This currently dies on macOS (see
606 // #11162), and isn't necessary there anyway
607 if !sess.target.target.options.is_like_osx {
618 fn write_rlib_bytecode_object_v1(writer: &mut Write,
619 bc_data_deflated: &[u8]) -> io::Result<()> {
620 let bc_data_deflated_size: u64 = bc_data_deflated.len() as u64;
622 writer.write_all(RLIB_BYTECODE_OBJECT_MAGIC)?;
623 writer.write_all(&[1, 0, 0, 0])?;
625 (bc_data_deflated_size >> 0) as u8,
626 (bc_data_deflated_size >> 8) as u8,
627 (bc_data_deflated_size >> 16) as u8,
628 (bc_data_deflated_size >> 24) as u8,
629 (bc_data_deflated_size >> 32) as u8,
630 (bc_data_deflated_size >> 40) as u8,
631 (bc_data_deflated_size >> 48) as u8,
632 (bc_data_deflated_size >> 56) as u8,
634 writer.write_all(&bc_data_deflated)?;
636 let number_of_bytes_written_so_far =
637 RLIB_BYTECODE_OBJECT_MAGIC.len() + // magic id
638 mem::size_of_val(&RLIB_BYTECODE_OBJECT_VERSION) + // version
639 mem::size_of_val(&bc_data_deflated_size) + // data size field
640 bc_data_deflated_size as usize; // actual data
642 // If the number of bytes written to the object so far is odd, add a
643 // padding byte to make it even. This works around a crash bug in LLDB
644 // (see issue #15950)
645 if number_of_bytes_written_so_far % 2 == 1 {
646 writer.write_all(&[0])?;
652 // Create a static archive
654 // This is essentially the same thing as an rlib, but it also involves adding
655 // all of the upstream crates' objects into the archive. This will slurp in
656 // all of the native libraries of upstream dependencies as well.
658 // Additionally, there's no way for us to link dynamic libraries, so we warn
659 // about all dynamic library dependencies that they're not linked in.
661 // There's no need to include metadata in a static archive, so ensure to not
662 // link in the metadata object file (and also don't prepare the archive with a
664 fn link_staticlib(sess: &Session, objects: &[PathBuf], out_filename: &Path,
666 let mut ab = link_rlib(sess, None, objects, out_filename, tempdir);
667 let mut all_native_libs = vec![];
669 each_linked_rlib(sess, &mut |cnum, path| {
670 let name = sess.cstore.crate_name(cnum);
671 let native_libs = sess.cstore.native_libraries(cnum);
673 // Here when we include the rlib into our staticlib we need to make a
674 // decision whether to include the extra object files along the way.
675 // These extra object files come from statically included native
676 // libraries, but they may be cfg'd away with #[link(cfg(..))].
678 // This unstable feature, though, only needs liblibc to work. The only
679 // use case there is where musl is statically included in liblibc.rlib,
680 // so if we don't want the included version we just need to skip it. As
681 // a result the logic here is that if *any* linked library is cfg'd away
682 // we just skip all object files.
684 // Clearly this is not sufficient for a general purpose feature, and
685 // we'd want to read from the library's metadata to determine which
686 // object files come from where and selectively skip them.
687 let skip_object_files = native_libs.iter().any(|lib| {
688 lib.kind == NativeLibraryKind::NativeStatic && !relevant_lib(sess, lib)
690 ab.add_rlib(path, &name.as_str(), sess.lto(), skip_object_files).unwrap();
692 all_native_libs.extend(sess.cstore.native_libraries(cnum));
698 if !all_native_libs.is_empty() {
699 sess.note_without_error("link against the following native artifacts when linking against \
700 this static library");
701 sess.note_without_error("the order and any duplication can be significant on some \
702 platforms, and so may need to be preserved");
705 for lib in all_native_libs.iter().filter(|l| relevant_lib(sess, l)) {
706 let name = match lib.kind {
707 NativeLibraryKind::NativeStaticNobundle |
708 NativeLibraryKind::NativeUnknown => "library",
709 NativeLibraryKind::NativeFramework => "framework",
710 // These are included, no need to print them
711 NativeLibraryKind::NativeStatic => continue,
713 sess.note_without_error(&format!("{}: {}", name, lib.name));
717 // Create a dynamic library or executable
719 // This will invoke the system linker/cc to create the resulting file. This
720 // links to all upstream files as well.
721 fn link_natively(sess: &Session,
722 crate_type: config::CrateType,
725 trans: &CrateTranslation,
726 outputs: &OutputFilenames,
728 info!("preparing {:?} from {:?} to {:?}", crate_type, objects, out_filename);
729 let flavor = sess.linker_flavor();
731 // The invocations of cc share some flags across platforms
732 let (pname, mut cmd, envs) = get_linker(sess);
733 // This will set PATH on windows
736 let root = sess.target_filesearch(PathKind::Native).get_lib_path();
737 if let Some(args) = sess.target.target.options.pre_link_args.get(&flavor) {
740 if let Some(ref args) = sess.opts.debugging_opts.pre_link_args {
743 cmd.args(&sess.opts.debugging_opts.pre_link_arg);
745 let pre_link_objects = if crate_type == config::CrateTypeExecutable {
746 &sess.target.target.options.pre_link_objects_exe
748 &sess.target.target.options.pre_link_objects_dll
750 for obj in pre_link_objects {
751 cmd.arg(root.join(obj));
754 if sess.target.target.options.is_like_emscripten {
756 cmd.arg(if sess.panic_strategy() == PanicStrategy::Abort {
757 "DISABLE_EXCEPTION_CATCHING=1"
759 "DISABLE_EXCEPTION_CATCHING=0"
764 let mut linker = trans.linker_info.to_linker(cmd, &sess);
765 link_args(&mut *linker, sess, crate_type, tmpdir,
766 objects, out_filename, outputs, trans);
767 cmd = linker.finalize();
769 if let Some(args) = sess.target.target.options.late_link_args.get(&flavor) {
772 for obj in &sess.target.target.options.post_link_objects {
773 cmd.arg(root.join(obj));
775 if let Some(args) = sess.target.target.options.post_link_args.get(&flavor) {
779 if sess.opts.debugging_opts.print_link_args {
780 println!("{:?}", &cmd);
783 // May have not found libraries in the right formats.
784 sess.abort_if_errors();
786 // Invoke the system linker
788 // Note that there's a terribly awful hack that really shouldn't be present
789 // in any compiler. Here an environment variable is supported to
790 // automatically retry the linker invocation if the linker looks like it
793 // Gee that seems odd, normally segfaults are things we want to know about!
794 // Unfortunately though in rust-lang/rust#38878 we're experiencing the
795 // linker segfaulting on Travis quite a bit which is causing quite a bit of
796 // pain to land PRs when they spuriously fail due to a segfault.
798 // The issue #38878 has some more debugging information on it as well, but
799 // this unfortunately looks like it's just a race condition in macOS's linker
800 // with some thread pool working in the background. It seems that no one
801 // currently knows a fix for this so in the meantime we're left with this...
803 let retry_on_segfault = env::var("RUSTC_RETRY_LINKER_ON_SEGFAULT").is_ok();
808 prog = time(sess.time_passes(), "running linker", || cmd.output());
809 if !retry_on_segfault || i > 3 {
812 let output = match prog {
813 Ok(ref output) => output,
816 if output.status.success() {
819 let mut out = output.stderr.clone();
820 out.extend(&output.stdout);
821 let out = String::from_utf8_lossy(&out);
822 let msg = "clang: error: unable to execute command: \
823 Segmentation fault: 11";
824 if !out.contains(msg) {
828 sess.struct_warn("looks like the linker segfaulted when we tried to \
829 call it, automatically retrying again")
830 .note(&format!("{:?}", cmd))
837 fn escape_string(s: &[u8]) -> String {
838 str::from_utf8(s).map(|s| s.to_owned())
839 .unwrap_or_else(|_| {
840 let mut x = "Non-UTF-8 output: ".to_string();
842 .flat_map(|&b| ascii::escape_default(b))
843 .map(|b| char::from_u32(b as u32).unwrap()));
847 if !prog.status.success() {
848 let mut output = prog.stderr.clone();
849 output.extend_from_slice(&prog.stdout);
850 sess.struct_err(&format!("linking with `{}` failed: {}",
853 .note(&format!("{:?}", &cmd))
854 .note(&escape_string(&output))
856 sess.abort_if_errors();
858 info!("linker stderr:\n{}", escape_string(&prog.stderr));
859 info!("linker stdout:\n{}", escape_string(&prog.stdout));
862 sess.struct_err(&format!("could not exec the linker `{}`: {}", pname, e))
863 .note(&format!("{:?}", &cmd))
865 if sess.target.target.options.is_like_msvc && e.kind() == io::ErrorKind::NotFound {
866 sess.note_without_error("the msvc targets depend on the msvc linker \
867 but `link.exe` was not found");
868 sess.note_without_error("please ensure that VS 2013 or VS 2015 was installed \
869 with the Visual C++ option");
871 sess.abort_if_errors();
876 // On macOS, debuggers need this utility to get run to do some munging of
878 if sess.target.target.options.is_like_osx && sess.opts.debuginfo != NoDebugInfo {
879 match Command::new("dsymutil").arg(out_filename).output() {
881 Err(e) => sess.fatal(&format!("failed to run dsymutil: {}", e)),
886 fn link_args(cmd: &mut Linker,
888 crate_type: config::CrateType,
892 outputs: &OutputFilenames,
893 trans: &CrateTranslation) {
895 // The default library location, we need this to find the runtime.
896 // The location of crates will be determined as needed.
897 let lib_path = sess.target_filesearch(PathKind::All).get_lib_path();
900 let t = &sess.target.target;
902 cmd.include_path(&fix_windows_verbatim_for_gcc(&lib_path));
906 cmd.output_filename(out_filename);
908 if crate_type == config::CrateTypeExecutable &&
909 sess.target.target.options.is_like_windows {
910 if let Some(ref s) = trans.windows_subsystem {
915 // If we're building a dynamic library then some platforms need to make sure
916 // that all symbols are exported correctly from the dynamic library.
917 if crate_type != config::CrateTypeExecutable ||
918 sess.target.target.options.is_like_emscripten {
919 cmd.export_symbols(tmpdir, crate_type);
922 // When linking a dynamic library, we put the metadata into a section of the
923 // executable. This metadata is in a separate object file from the main
924 // object file, so we link that in here.
925 if crate_type == config::CrateTypeDylib ||
926 crate_type == config::CrateTypeProcMacro {
927 cmd.add_object(&outputs.with_extension(METADATA_OBJ_NAME));
930 // Try to strip as much out of the generated object by removing unused
931 // sections if possible. See more comments in linker.rs
932 if !sess.opts.cg.link_dead_code {
933 let keep_metadata = crate_type == config::CrateTypeDylib;
934 cmd.gc_sections(keep_metadata);
937 let used_link_args = sess.cstore.used_link_args();
939 if crate_type == config::CrateTypeExecutable &&
940 t.options.position_independent_executables {
941 let empty_vec = Vec::new();
942 let args = sess.opts.cg.link_args.as_ref().unwrap_or(&empty_vec);
943 let more_args = &sess.opts.cg.link_arg;
944 let mut args = args.iter().chain(more_args.iter()).chain(used_link_args.iter());
946 if get_reloc_model(sess) == llvm::RelocMode::PIC
947 && !args.any(|x| *x == "-static") {
948 cmd.position_independent_executable();
952 // Pass optimization flags down to the linker.
955 // Pass debuginfo flags down to the linker.
958 // We want to prevent the compiler from accidentally leaking in any system
959 // libraries, so we explicitly ask gcc to not link to any libraries by
960 // default. Note that this does not happen for windows because windows pulls
961 // in some large number of libraries and I couldn't quite figure out which
963 if t.options.no_default_libraries {
964 cmd.no_default_libraries();
967 // Take careful note of the ordering of the arguments we pass to the linker
968 // here. Linkers will assume that things on the left depend on things to the
969 // right. Things on the right cannot depend on things on the left. This is
970 // all formally implemented in terms of resolving symbols (libs on the right
971 // resolve unknown symbols of libs on the left, but not vice versa).
973 // For this reason, we have organized the arguments we pass to the linker as
976 // 1. The local object that LLVM just generated
977 // 2. Local native libraries
978 // 3. Upstream rust libraries
979 // 4. Upstream native libraries
981 // The rationale behind this ordering is that those items lower down in the
982 // list can't depend on items higher up in the list. For example nothing can
983 // depend on what we just generated (e.g. that'd be a circular dependency).
984 // Upstream rust libraries are not allowed to depend on our local native
985 // libraries as that would violate the structure of the DAG, in that
986 // scenario they are required to link to them as well in a shared fashion.
988 // Note that upstream rust libraries may contain native dependencies as
989 // well, but they also can't depend on what we just started to add to the
990 // link line. And finally upstream native libraries can't depend on anything
991 // in this DAG so far because they're only dylibs and dylibs can only depend
992 // on other dylibs (e.g. other native deps).
993 add_local_native_libraries(cmd, sess);
994 add_upstream_rust_crates(cmd, sess, crate_type, tmpdir);
995 add_upstream_native_libraries(cmd, sess, crate_type);
997 // # Telling the linker what we're doing
999 if crate_type != config::CrateTypeExecutable {
1000 cmd.build_dylib(out_filename);
1003 // FIXME (#2397): At some point we want to rpath our guesses as to
1004 // where extern libraries might live, based on the
1005 // addl_lib_search_paths
1006 if sess.opts.cg.rpath {
1007 let sysroot = sess.sysroot();
1008 let target_triple = &sess.opts.target_triple;
1009 let mut get_install_prefix_lib_path = || {
1010 let install_prefix = option_env!("CFG_PREFIX").expect("CFG_PREFIX");
1011 let tlib = filesearch::relative_target_lib_path(sysroot, target_triple);
1012 let mut path = PathBuf::from(install_prefix);
1017 let mut rpath_config = RPathConfig {
1018 used_crates: sess.cstore.used_crates(LinkagePreference::RequireDynamic),
1019 out_filename: out_filename.to_path_buf(),
1020 has_rpath: sess.target.target.options.has_rpath,
1021 is_like_osx: sess.target.target.options.is_like_osx,
1022 linker_is_gnu: sess.target.target.options.linker_is_gnu,
1023 get_install_prefix_lib_path: &mut get_install_prefix_lib_path,
1025 cmd.args(&rpath::get_rpath_flags(&mut rpath_config));
1028 // Finally add all the linker arguments provided on the command line along
1029 // with any #[link_args] attributes found inside the crate
1030 if let Some(ref args) = sess.opts.cg.link_args {
1033 cmd.args(&sess.opts.cg.link_arg);
1034 cmd.args(&used_link_args);
1037 // # Native library linking
1039 // User-supplied library search paths (-L on the command line). These are
1040 // the same paths used to find Rust crates, so some of them may have been
1041 // added already by the previous crate linking code. This only allows them
1042 // to be found at compile time so it is still entirely up to outside
1043 // forces to make sure that library can be found at runtime.
1045 // Also note that the native libraries linked here are only the ones located
1046 // in the current crate. Upstream crates with native library dependencies
1047 // may have their native library pulled in above.
1048 fn add_local_native_libraries(cmd: &mut Linker, sess: &Session) {
1049 sess.target_filesearch(PathKind::All).for_each_lib_search_path(|path, k| {
1051 PathKind::Framework => { cmd.framework_path(path); }
1052 _ => { cmd.include_path(&fix_windows_verbatim_for_gcc(path)); }
1056 let relevant_libs = sess.cstore.used_libraries().into_iter().filter(|l| {
1057 relevant_lib(sess, l)
1060 let search_path = archive_search_paths(sess);
1061 for lib in relevant_libs {
1063 NativeLibraryKind::NativeUnknown => cmd.link_dylib(&lib.name.as_str()),
1064 NativeLibraryKind::NativeFramework => cmd.link_framework(&lib.name.as_str()),
1065 NativeLibraryKind::NativeStaticNobundle => cmd.link_staticlib(&lib.name.as_str()),
1066 NativeLibraryKind::NativeStatic => cmd.link_whole_staticlib(&lib.name.as_str(),
1072 // # Rust Crate linking
1074 // Rust crates are not considered at all when creating an rlib output. All
1075 // dependencies will be linked when producing the final output (instead of
1076 // the intermediate rlib version)
1077 fn add_upstream_rust_crates(cmd: &mut Linker,
1079 crate_type: config::CrateType,
1081 // All of the heavy lifting has previously been accomplished by the
1082 // dependency_format module of the compiler. This is just crawling the
1083 // output of that module, adding crates as necessary.
1085 // Linking to a rlib involves just passing it to the linker (the linker
1086 // will slurp up the object files inside), and linking to a dynamic library
1087 // involves just passing the right -l flag.
1089 let formats = sess.dependency_formats.borrow();
1090 let data = formats.get(&crate_type).unwrap();
1092 // Invoke get_used_crates to ensure that we get a topological sorting of
1094 let deps = sess.cstore.used_crates(LinkagePreference::RequireDynamic);
1096 let mut compiler_builtins = None;
1098 for &(cnum, _) in &deps {
1099 // We may not pass all crates through to the linker. Some crates may
1100 // appear statically in an existing dylib, meaning we'll pick up all the
1101 // symbols from the dylib.
1102 let src = sess.cstore.used_crate_source(cnum);
1103 match data[cnum.as_usize() - 1] {
1104 _ if sess.cstore.is_sanitizer_runtime(cnum) => {
1105 link_sanitizer_runtime(cmd, sess, tmpdir, cnum);
1107 // compiler-builtins are always placed last to ensure that they're
1108 // linked correctly.
1109 _ if sess.cstore.is_compiler_builtins(cnum) => {
1110 assert!(compiler_builtins.is_none());
1111 compiler_builtins = Some(cnum);
1113 Linkage::NotLinked |
1114 Linkage::IncludedFromDylib => {}
1115 Linkage::Static => {
1116 add_static_crate(cmd, sess, tmpdir, crate_type, cnum);
1118 Linkage::Dynamic => {
1119 add_dynamic_crate(cmd, sess, &src.dylib.unwrap().0)
1124 // compiler-builtins are always placed last to ensure that they're
1125 // linked correctly.
1126 // We must always link the `compiler_builtins` crate statically. Even if it
1127 // was already "included" in a dylib (e.g. `libstd` when `-C prefer-dynamic`
1129 if let Some(cnum) = compiler_builtins {
1130 add_static_crate(cmd, sess, tmpdir, crate_type, cnum);
1133 // Converts a library file-stem into a cc -l argument
1134 fn unlib<'a>(config: &config::Config, stem: &'a str) -> &'a str {
1135 if stem.starts_with("lib") && !config.target.options.is_like_windows {
1142 // We must link the sanitizer runtime using -Wl,--whole-archive but since
1143 // it's packed in a .rlib, it contains stuff that are not objects that will
1144 // make the linker error. So we must remove those bits from the .rlib before
1146 fn link_sanitizer_runtime(cmd: &mut Linker,
1150 let src = sess.cstore.used_crate_source(cnum);
1151 let cratepath = &src.rlib.unwrap().0;
1153 if sess.target.target.options.is_like_osx {
1154 // On Apple platforms, the sanitizer is always built as a dylib, and
1155 // LLVM will link to `@rpath/*.dylib`, so we need to specify an
1156 // rpath to the library as well (the rpath should be absolute, see
1157 // PR #41352 for details).
1159 // FIXME: Remove this logic into librustc_*san once Cargo supports it
1160 let rpath = cratepath.parent().unwrap();
1161 let rpath = rpath.to_str().expect("non-utf8 component in path");
1162 cmd.args(&["-Wl,-rpath".into(), "-Xlinker".into(), rpath.into()]);
1165 let dst = tmpdir.join(cratepath.file_name().unwrap());
1166 let cfg = archive_config(sess, &dst, Some(cratepath));
1167 let mut archive = ArchiveBuilder::new(cfg);
1168 archive.update_symbols();
1170 for f in archive.src_files() {
1171 if f.ends_with("bytecode.deflate") || f == METADATA_FILENAME {
1172 archive.remove_file(&f);
1179 cmd.link_whole_rlib(&dst);
1182 // Adds the static "rlib" versions of all crates to the command line.
1183 // There's a bit of magic which happens here specifically related to LTO and
1184 // dynamic libraries. Specifically:
1186 // * For LTO, we remove upstream object files.
1187 // * For dylibs we remove metadata and bytecode from upstream rlibs
1189 // When performing LTO, almost(*) all of the bytecode from the upstream
1190 // libraries has already been included in our object file output. As a
1191 // result we need to remove the object files in the upstream libraries so
1192 // the linker doesn't try to include them twice (or whine about duplicate
1193 // symbols). We must continue to include the rest of the rlib, however, as
1194 // it may contain static native libraries which must be linked in.
1196 // (*) Crates marked with `#![no_builtins]` don't participate in LTO and
1197 // their bytecode wasn't included. The object files in those libraries must
1198 // still be passed to the linker.
1200 // When making a dynamic library, linkers by default don't include any
1201 // object files in an archive if they're not necessary to resolve the link.
1202 // We basically want to convert the archive (rlib) to a dylib, though, so we
1203 // *do* want everything included in the output, regardless of whether the
1204 // linker thinks it's needed or not. As a result we must use the
1205 // --whole-archive option (or the platform equivalent). When using this
1206 // option the linker will fail if there are non-objects in the archive (such
1207 // as our own metadata and/or bytecode). All in all, for rlibs to be
1208 // entirely included in dylibs, we need to remove all non-object files.
1210 // Note, however, that if we're not doing LTO or we're not producing a dylib
1211 // (aka we're making an executable), we can just pass the rlib blindly to
1212 // the linker (fast) because it's fine if it's not actually included as
1213 // we're at the end of the dependency chain.
1214 fn add_static_crate(cmd: &mut Linker,
1217 crate_type: config::CrateType,
1219 let src = sess.cstore.used_crate_source(cnum);
1220 let cratepath = &src.rlib.unwrap().0;
1222 // See the comment above in `link_staticlib` and `link_rlib` for why if
1223 // there's a static library that's not relevant we skip all object
1225 let native_libs = sess.cstore.native_libraries(cnum);
1226 let skip_native = native_libs.iter().any(|lib| {
1227 lib.kind == NativeLibraryKind::NativeStatic && !relevant_lib(sess, lib)
1230 if !sess.lto() && crate_type != config::CrateTypeDylib && !skip_native {
1231 cmd.link_rlib(&fix_windows_verbatim_for_gcc(cratepath));
1235 let dst = tmpdir.join(cratepath.file_name().unwrap());
1236 let name = cratepath.file_name().unwrap().to_str().unwrap();
1237 let name = &name[3..name.len() - 5]; // chop off lib/.rlib
1239 time(sess.time_passes(), &format!("altering {}.rlib", name), || {
1240 let cfg = archive_config(sess, &dst, Some(cratepath));
1241 let mut archive = ArchiveBuilder::new(cfg);
1242 archive.update_symbols();
1244 let mut any_objects = false;
1245 for f in archive.src_files() {
1246 if f.ends_with("bytecode.deflate") || f == METADATA_FILENAME {
1247 archive.remove_file(&f);
1251 let canonical = f.replace("-", "_");
1252 let canonical_name = name.replace("-", "_");
1254 let is_rust_object =
1255 canonical.starts_with(&canonical_name) && {
1256 let num = &f[name.len()..f.len() - 2];
1257 num.len() > 0 && num[1..].parse::<u32>().is_ok()
1260 // If we've been requested to skip all native object files
1261 // (those not generated by the rust compiler) then we can skip
1262 // this file. See above for why we may want to do this.
1263 let skip_because_cfg_say_so = skip_native && !is_rust_object;
1265 // If we're performing LTO and this is a rust-generated object
1266 // file, then we don't need the object file as it's part of the
1267 // LTO module. Note that `#![no_builtins]` is excluded from LTO,
1268 // though, so we let that object file slide.
1269 let skip_because_lto = sess.lto() && is_rust_object &&
1270 !sess.cstore.is_no_builtins(cnum);
1272 if skip_because_cfg_say_so || skip_because_lto {
1273 archive.remove_file(&f);
1284 // If we're creating a dylib, then we need to include the
1285 // whole of each object in our archive into that artifact. This is
1286 // because a `dylib` can be reused as an intermediate artifact.
1288 // Note, though, that we don't want to include the whole of a
1289 // compiler-builtins crate (e.g. compiler-rt) because it'll get
1290 // repeatedly linked anyway.
1291 if crate_type == config::CrateTypeDylib &&
1292 !sess.cstore.is_compiler_builtins(cnum) {
1293 cmd.link_whole_rlib(&fix_windows_verbatim_for_gcc(&dst));
1295 cmd.link_rlib(&fix_windows_verbatim_for_gcc(&dst));
1300 // Same thing as above, but for dynamic crates instead of static crates.
1301 fn add_dynamic_crate(cmd: &mut Linker, sess: &Session, cratepath: &Path) {
1302 // If we're performing LTO, then it should have been previously required
1303 // that all upstream rust dependencies were available in an rlib format.
1304 assert!(!sess.lto());
1306 // Just need to tell the linker about where the library lives and
1308 let parent = cratepath.parent();
1309 if let Some(dir) = parent {
1310 cmd.include_path(&fix_windows_verbatim_for_gcc(dir));
1312 let filestem = cratepath.file_stem().unwrap().to_str().unwrap();
1313 cmd.link_rust_dylib(&unlib(&sess.target, filestem),
1314 parent.unwrap_or(Path::new("")));
1318 // Link in all of our upstream crates' native dependencies. Remember that
1319 // all of these upstream native dependencies are all non-static
1320 // dependencies. We've got two cases then:
1322 // 1. The upstream crate is an rlib. In this case we *must* link in the
1323 // native dependency because the rlib is just an archive.
1325 // 2. The upstream crate is a dylib. In order to use the dylib, we have to
1326 // have the dependency present on the system somewhere. Thus, we don't
1327 // gain a whole lot from not linking in the dynamic dependency to this
1330 // The use case for this is a little subtle. In theory the native
1331 // dependencies of a crate are purely an implementation detail of the crate
1332 // itself, but the problem arises with generic and inlined functions. If a
1333 // generic function calls a native function, then the generic function must
1334 // be instantiated in the target crate, meaning that the native symbol must
1335 // also be resolved in the target crate.
1336 fn add_upstream_native_libraries(cmd: &mut Linker, sess: &Session, crate_type: config::CrateType) {
1337 // Be sure to use a topological sorting of crates because there may be
1338 // interdependencies between native libraries. When passing -nodefaultlibs,
1339 // for example, almost all native libraries depend on libc, so we have to
1340 // make sure that's all the way at the right (liblibc is near the base of
1341 // the dependency chain).
1343 // This passes RequireStatic, but the actual requirement doesn't matter,
1344 // we're just getting an ordering of crate numbers, we're not worried about
1346 let formats = sess.dependency_formats.borrow();
1347 let data = formats.get(&crate_type).unwrap();
1349 let crates = sess.cstore.used_crates(LinkagePreference::RequireStatic);
1350 for (cnum, _) in crates {
1351 for lib in sess.cstore.native_libraries(cnum) {
1352 if !relevant_lib(sess, &lib) {
1356 NativeLibraryKind::NativeUnknown => cmd.link_dylib(&lib.name.as_str()),
1357 NativeLibraryKind::NativeFramework => cmd.link_framework(&lib.name.as_str()),
1358 NativeLibraryKind::NativeStaticNobundle => {
1359 // Link "static-nobundle" native libs only if the crate they originate from
1360 // is being linked statically to the current crate. If it's linked dynamically
1361 // or is an rlib already included via some other dylib crate, the symbols from
1362 // native libs will have already been included in that dylib.
1363 if data[cnum.as_usize() - 1] == Linkage::Static {
1364 cmd.link_staticlib(&lib.name.as_str())
1367 // ignore statically included native libraries here as we've
1368 // already included them when we included the rust library
1370 NativeLibraryKind::NativeStatic => {}
1376 fn relevant_lib(sess: &Session, lib: &NativeLibrary) -> bool {
1378 Some(ref cfg) => attr::cfg_matches(cfg, &sess.parse_sess, None),