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;
38 use std::ffi::OsString;
40 use std::io::{self, Read, Write};
42 use std::path::{Path, PathBuf};
43 use std::process::Command;
48 use syntax::symbol::Symbol;
51 // RLIB LLVM-BYTECODE OBJECT LAYOUT
54 // 0..10 "RUST_OBJECT" encoded in ASCII
55 // 11..14 format version as little-endian u32
56 // 15..22 size in bytes of deflate compressed LLVM bitcode as
58 // 23.. compressed LLVM bitcode
60 // This is the "magic number" expected at the beginning of a LLVM bytecode
62 pub const RLIB_BYTECODE_OBJECT_MAGIC: &'static [u8] = b"RUST_OBJECT";
64 // The version number this compiler will write to bytecode objects in rlibs
65 pub const RLIB_BYTECODE_OBJECT_VERSION: u32 = 1;
67 // The offset in bytes the bytecode object format version number can be found at
68 pub const RLIB_BYTECODE_OBJECT_VERSION_OFFSET: usize = 11;
70 // The offset in bytes the size of the compressed bytecode can be found at in
72 pub const RLIB_BYTECODE_OBJECT_V1_DATASIZE_OFFSET: usize =
73 RLIB_BYTECODE_OBJECT_VERSION_OFFSET + 4;
75 // The offset in bytes the compressed LLVM bytecode can be found at in format
77 pub const RLIB_BYTECODE_OBJECT_V1_DATA_OFFSET: usize =
78 RLIB_BYTECODE_OBJECT_V1_DATASIZE_OFFSET + 8;
81 pub fn find_crate_name(sess: Option<&Session>,
82 attrs: &[ast::Attribute],
83 input: &Input) -> String {
84 let validate = |s: String, span: Option<Span>| {
85 cstore::validate_crate_name(sess, &s[..], span);
89 // Look in attributes 100% of the time to make sure the attribute is marked
90 // as used. After doing this, however, we still prioritize a crate name from
91 // the command line over one found in the #[crate_name] attribute. If we
92 // find both we ensure that they're the same later on as well.
93 let attr_crate_name = attrs.iter().find(|at| at.check_name("crate_name"))
94 .and_then(|at| at.value_str().map(|s| (at, s)));
96 if let Some(sess) = sess {
97 if let Some(ref s) = sess.opts.crate_name {
98 if let Some((attr, name)) = attr_crate_name {
100 let msg = format!("--crate-name and #[crate_name] are \
101 required to match, but `{}` != `{}`",
103 sess.span_err(attr.span, &msg[..]);
106 return validate(s.clone(), None);
110 if let Some((attr, s)) = attr_crate_name {
111 return validate(s.to_string(), Some(attr.span));
113 if let Input::File(ref path) = *input {
114 if let Some(s) = path.file_stem().and_then(|s| s.to_str()) {
115 if s.starts_with("-") {
116 let msg = format!("crate names cannot start with a `-`, but \
117 `{}` has a leading hyphen", s);
118 if let Some(sess) = sess {
122 return validate(s.replace("-", "_"), None);
127 "rust_out".to_string()
130 pub fn build_link_meta(incremental_hashes_map: &IncrementalHashesMap,
134 crate_name: Symbol::intern(name),
135 crate_hash: Svh::new(incremental_hashes_map[&DepNode::Krate].to_smaller_hash()),
141 // The third parameter is for an extra path to add to PATH for MSVC
142 // cross linkers for host toolchain DLL dependencies
143 pub fn get_linker(sess: &Session) -> (String, Command, Option<PathBuf>) {
144 if let Some(ref linker) = sess.opts.cg.linker {
145 (linker.clone(), Command::new(linker), None)
146 } else if sess.target.target.options.is_like_msvc {
147 let (cmd, host) = msvc::link_exe_cmd(sess);
148 ("link.exe".to_string(), cmd, host)
150 (sess.target.target.options.linker.clone(),
151 Command::new(&sess.target.target.options.linker), None)
155 pub fn get_ar_prog(sess: &Session) -> String {
156 sess.opts.cg.ar.clone().unwrap_or_else(|| {
157 sess.target.target.options.ar.clone()
161 fn command_path(sess: &Session, extra: Option<PathBuf>) -> OsString {
162 // The compiler's sysroot often has some bundled tools, so add it to the
163 // PATH for the child.
164 let mut new_path = sess.host_filesearch(PathKind::All)
165 .get_tools_search_paths();
166 if let Some(path) = env::var_os("PATH") {
167 new_path.extend(env::split_paths(&path));
169 new_path.extend(extra);
170 env::join_paths(new_path).unwrap()
173 pub fn remove(sess: &Session, path: &Path) {
174 match fs::remove_file(path) {
177 sess.err(&format!("failed to remove {}: {}",
184 /// Perform the linkage portion of the compilation phase. This will generate all
185 /// of the requested outputs for this compilation session.
186 pub fn link_binary(sess: &Session,
187 trans: &CrateTranslation,
188 outputs: &OutputFilenames,
189 crate_name: &str) -> Vec<PathBuf> {
190 let _task = sess.dep_graph.in_task(DepNode::LinkBinary);
192 let mut out_filenames = Vec::new();
193 for &crate_type in sess.crate_types.borrow().iter() {
194 // Ignore executable crates if we have -Z no-trans, as they will error.
195 if (sess.opts.debugging_opts.no_trans ||
196 !sess.opts.output_types.should_trans()) &&
197 crate_type == config::CrateTypeExecutable {
201 if invalid_output_for_target(sess, crate_type) {
202 bug!("invalid output type `{:?}` for target os `{}`",
203 crate_type, sess.opts.target_triple);
205 let mut out_files = link_binary_output(sess, trans, crate_type, outputs, crate_name);
206 out_filenames.append(&mut out_files);
209 // Remove the temporary object file and metadata if we aren't saving temps
210 if !sess.opts.cg.save_temps {
211 if sess.opts.output_types.should_trans() {
212 for obj in object_filenames(trans, outputs) {
216 remove(sess, &outputs.with_extension("metadata.o"));
223 /// Returns default crate type for target
225 /// Default crate type is used when crate type isn't provided neither
226 /// through cmd line arguments nor through crate attributes
228 /// It is CrateTypeExecutable for all platforms but iOS as there is no
229 /// way to run iOS binaries anyway without jailbreaking and
230 /// interaction with Rust code through static library is the only
232 pub fn default_output_for_target(sess: &Session) -> config::CrateType {
233 if !sess.target.target.options.executables {
234 config::CrateTypeStaticlib
236 config::CrateTypeExecutable
240 /// Checks if target supports crate_type as output
241 pub fn invalid_output_for_target(sess: &Session,
242 crate_type: config::CrateType) -> bool {
243 match (sess.target.target.options.dynamic_linking,
244 sess.target.target.options.executables, crate_type) {
245 (false, _, config::CrateTypeCdylib) |
246 (false, _, config::CrateTypeProcMacro) |
247 (false, _, config::CrateTypeDylib) => true,
248 (_, false, config::CrateTypeExecutable) => true,
253 fn is_writeable(p: &Path) -> bool {
256 Ok(m) => !m.permissions().readonly()
260 fn filename_for_metadata(sess: &Session, crate_name: &str, outputs: &OutputFilenames) -> PathBuf {
261 let out_filename = outputs.single_output_file.clone()
264 .join(&format!("lib{}{}.rmeta", crate_name, sess.opts.cg.extra_filename)));
265 check_file_is_writeable(&out_filename, sess);
269 pub fn filename_for_input(sess: &Session,
270 crate_type: config::CrateType,
272 outputs: &OutputFilenames) -> PathBuf {
273 let libname = format!("{}{}", crate_name, sess.opts.cg.extra_filename);
276 config::CrateTypeRlib => {
277 outputs.out_directory.join(&format!("lib{}.rlib", libname))
279 config::CrateTypeCdylib |
280 config::CrateTypeProcMacro |
281 config::CrateTypeDylib => {
282 let (prefix, suffix) = (&sess.target.target.options.dll_prefix,
283 &sess.target.target.options.dll_suffix);
284 outputs.out_directory.join(&format!("{}{}{}", prefix, libname,
287 config::CrateTypeStaticlib => {
288 let (prefix, suffix) = (&sess.target.target.options.staticlib_prefix,
289 &sess.target.target.options.staticlib_suffix);
290 outputs.out_directory.join(&format!("{}{}{}", prefix, libname,
293 config::CrateTypeExecutable => {
294 let suffix = &sess.target.target.options.exe_suffix;
295 let out_filename = outputs.path(OutputType::Exe);
296 if suffix.is_empty() {
297 out_filename.to_path_buf()
299 out_filename.with_extension(&suffix[1..])
305 pub fn each_linked_rlib(sess: &Session,
306 f: &mut FnMut(CrateNum, &Path)) {
307 let crates = sess.cstore.used_crates(LinkagePreference::RequireStatic).into_iter();
308 let fmts = sess.dependency_formats.borrow();
309 let fmts = fmts.get(&config::CrateTypeExecutable)
310 .or_else(|| fmts.get(&config::CrateTypeStaticlib))
311 .or_else(|| fmts.get(&config::CrateTypeCdylib))
312 .or_else(|| fmts.get(&config::CrateTypeProcMacro));
313 let fmts = fmts.unwrap_or_else(|| {
314 bug!("could not find formats for rlibs");
316 for (cnum, path) in crates {
317 match fmts[cnum.as_usize() - 1] {
318 Linkage::NotLinked | Linkage::IncludedFromDylib => continue,
321 let name = sess.cstore.crate_name(cnum).clone();
322 let path = match path {
323 LibSource::Some(p) => p,
324 LibSource::MetadataOnly => {
325 sess.fatal(&format!("could not find rlib for: `{}`, found rmeta (metadata) file",
329 sess.fatal(&format!("could not find rlib for: `{}`", name));
336 fn out_filename(sess: &Session,
337 crate_type: config::CrateType,
338 outputs: &OutputFilenames,
341 let default_filename = filename_for_input(sess, crate_type, crate_name, outputs);
342 let out_filename = outputs.outputs.get(&OutputType::Exe)
343 .and_then(|s| s.to_owned())
344 .or_else(|| outputs.single_output_file.clone())
345 .unwrap_or(default_filename);
347 check_file_is_writeable(&out_filename, sess);
352 // Make sure files are writeable. Mac, FreeBSD, and Windows system linkers
353 // check this already -- however, the Linux linker will happily overwrite a
354 // read-only file. We should be consistent.
355 fn check_file_is_writeable(file: &Path, sess: &Session) {
356 if !is_writeable(file) {
357 sess.fatal(&format!("output file {} is not writeable -- check its \
358 permissions", file.display()));
362 fn link_binary_output(sess: &Session,
363 trans: &CrateTranslation,
364 crate_type: config::CrateType,
365 outputs: &OutputFilenames,
366 crate_name: &str) -> Vec<PathBuf> {
367 let objects = object_filenames(trans, outputs);
369 for file in &objects {
370 check_file_is_writeable(file, sess);
373 let tmpdir = match TempDir::new("rustc") {
374 Ok(tmpdir) => tmpdir,
375 Err(err) => sess.fatal(&format!("couldn't create a temp dir: {}", err)),
378 let mut out_filenames = vec![];
380 if outputs.outputs.contains_key(&OutputType::Metadata) {
381 let out_filename = filename_for_metadata(sess, crate_name, outputs);
382 emit_metadata(sess, trans, &out_filename);
383 out_filenames.push(out_filename);
386 if outputs.outputs.should_trans() {
387 let out_filename = out_filename(sess, crate_type, outputs, crate_name);
389 config::CrateTypeRlib => {
390 link_rlib(sess, Some(trans), &objects, &out_filename,
391 tmpdir.path()).build();
393 config::CrateTypeStaticlib => {
394 link_staticlib(sess, &objects, &out_filename, tmpdir.path());
397 link_natively(sess, crate_type, &objects, &out_filename, trans,
398 outputs, tmpdir.path());
401 out_filenames.push(out_filename);
407 fn object_filenames(trans: &CrateTranslation,
408 outputs: &OutputFilenames)
410 trans.modules.iter().map(|module| {
411 outputs.temp_path(OutputType::Object, Some(&module.name[..]))
415 fn archive_search_paths(sess: &Session) -> Vec<PathBuf> {
416 let mut search = Vec::new();
417 sess.target_filesearch(PathKind::Native).for_each_lib_search_path(|path, _| {
418 search.push(path.to_path_buf());
423 fn archive_config<'a>(sess: &'a Session,
425 input: Option<&Path>) -> ArchiveConfig<'a> {
428 dst: output.to_path_buf(),
429 src: input.map(|p| p.to_path_buf()),
430 lib_search_paths: archive_search_paths(sess),
431 ar_prog: get_ar_prog(sess),
432 command_path: command_path(sess, None),
436 fn emit_metadata<'a>(sess: &'a Session, trans: &CrateTranslation, out_filename: &Path) {
437 let result = fs::File::create(out_filename).and_then(|mut f| f.write_all(&trans.metadata));
438 if let Err(e) = result {
439 sess.fatal(&format!("failed to write {}: {}", out_filename.display(), e));
445 // An rlib in its current incarnation is essentially a renamed .a file. The
446 // rlib primarily contains the object file of the crate, but it also contains
447 // all of the object files from native libraries. This is done by unzipping
448 // native libraries and inserting all of the contents into this archive.
449 fn link_rlib<'a>(sess: &'a Session,
450 trans: Option<&CrateTranslation>, // None == no metadata/bytecode
453 tmpdir: &Path) -> ArchiveBuilder<'a> {
454 info!("preparing rlib from {:?} to {:?}", objects, out_filename);
455 let mut ab = ArchiveBuilder::new(archive_config(sess, out_filename, None));
461 // Note that in this loop we are ignoring the value of `lib.cfg`. That is,
462 // we may not be configured to actually include a static library if we're
463 // adding it here. That's because later when we consume this rlib we'll
464 // decide whether we actually needed the static library or not.
466 // To do this "correctly" we'd need to keep track of which libraries added
467 // which object files to the archive. We don't do that here, however. The
468 // #[link(cfg(..))] feature is unstable, though, and only intended to get
469 // liblibc working. In that sense the check below just indicates that if
470 // there are any libraries we want to omit object files for at link time we
471 // just exclude all custom object files.
473 // Eventually if we want to stabilize or flesh out the #[link(cfg(..))]
474 // feature then we'll need to figure out how to record what objects were
475 // loaded from the libraries found here and then encode that into the
476 // metadata of the rlib we're generating somehow.
477 for lib in sess.cstore.used_libraries() {
479 NativeLibraryKind::NativeStatic => {}
480 NativeLibraryKind::NativeStaticNobundle |
481 NativeLibraryKind::NativeFramework |
482 NativeLibraryKind::NativeUnknown => continue,
484 ab.add_native_library(&lib.name.as_str());
487 // After adding all files to the archive, we need to update the
488 // symbol table of the archive.
491 // Note that it is important that we add all of our non-object "magical
492 // files" *after* all of the object files in the archive. The reason for
493 // this is as follows:
495 // * When performing LTO, this archive will be modified to remove
496 // objects from above. The reason for this is described below.
498 // * When the system linker looks at an archive, it will attempt to
499 // determine the architecture of the archive in order to see whether its
502 // The algorithm for this detection is: iterate over the files in the
503 // archive. Skip magical SYMDEF names. Interpret the first file as an
504 // object file. Read architecture from the object file.
506 // * As one can probably see, if "metadata" and "foo.bc" were placed
507 // before all of the objects, then the architecture of this archive would
508 // not be correctly inferred once 'foo.o' is removed.
510 // Basically, all this means is that this code should not move above the
514 // Instead of putting the metadata in an object file section, rlibs
515 // contain the metadata in a separate file. We use a temp directory
516 // here so concurrent builds in the same directory don't try to use
517 // the same filename for metadata (stomping over one another)
518 let metadata = tmpdir.join(sess.cstore.metadata_filename());
519 emit_metadata(sess, trans, &metadata);
520 ab.add_file(&metadata);
522 // For LTO purposes, the bytecode of this library is also inserted
523 // into the archive. If codegen_units > 1, we insert each of the
526 // Note that we make sure that the bytecode filename in the
527 // archive is never exactly 16 bytes long by adding a 16 byte
528 // extension to it. This is to work around a bug in LLDB that
529 // would cause it to crash if the name of a file in an archive
530 // was exactly 16 bytes.
531 let bc_filename = obj.with_extension("bc");
532 let bc_deflated_filename = tmpdir.join({
533 obj.with_extension("bytecode.deflate").file_name().unwrap()
536 let mut bc_data = Vec::new();
537 match fs::File::open(&bc_filename).and_then(|mut f| {
538 f.read_to_end(&mut bc_data)
541 Err(e) => sess.fatal(&format!("failed to read bytecode: {}",
545 let bc_data_deflated = flate::deflate_bytes(&bc_data[..]);
547 let mut bc_file_deflated = match fs::File::create(&bc_deflated_filename) {
550 sess.fatal(&format!("failed to create compressed \
551 bytecode file: {}", e))
555 match write_rlib_bytecode_object_v1(&mut bc_file_deflated,
559 sess.fatal(&format!("failed to write compressed \
564 ab.add_file(&bc_deflated_filename);
566 // See the bottom of back::write::run_passes for an explanation
567 // of when we do and don't keep .#module-name#.bc files around.
568 let user_wants_numbered_bitcode =
569 sess.opts.output_types.contains_key(&OutputType::Bitcode) &&
570 sess.opts.cg.codegen_units > 1;
571 if !sess.opts.cg.save_temps && !user_wants_numbered_bitcode {
572 remove(sess, &bc_filename);
576 // After adding all files to the archive, we need to update the
577 // symbol table of the archive. This currently dies on OSX (see
578 // #11162), and isn't necessary there anyway
579 if !sess.target.target.options.is_like_osx {
590 fn write_rlib_bytecode_object_v1(writer: &mut Write,
591 bc_data_deflated: &[u8]) -> io::Result<()> {
592 let bc_data_deflated_size: u64 = bc_data_deflated.len() as u64;
594 writer.write_all(RLIB_BYTECODE_OBJECT_MAGIC)?;
595 writer.write_all(&[1, 0, 0, 0])?;
597 (bc_data_deflated_size >> 0) as u8,
598 (bc_data_deflated_size >> 8) as u8,
599 (bc_data_deflated_size >> 16) as u8,
600 (bc_data_deflated_size >> 24) as u8,
601 (bc_data_deflated_size >> 32) as u8,
602 (bc_data_deflated_size >> 40) as u8,
603 (bc_data_deflated_size >> 48) as u8,
604 (bc_data_deflated_size >> 56) as u8,
606 writer.write_all(&bc_data_deflated)?;
608 let number_of_bytes_written_so_far =
609 RLIB_BYTECODE_OBJECT_MAGIC.len() + // magic id
610 mem::size_of_val(&RLIB_BYTECODE_OBJECT_VERSION) + // version
611 mem::size_of_val(&bc_data_deflated_size) + // data size field
612 bc_data_deflated_size as usize; // actual data
614 // If the number of bytes written to the object so far is odd, add a
615 // padding byte to make it even. This works around a crash bug in LLDB
616 // (see issue #15950)
617 if number_of_bytes_written_so_far % 2 == 1 {
618 writer.write_all(&[0])?;
624 // Create a static archive
626 // This is essentially the same thing as an rlib, but it also involves adding
627 // all of the upstream crates' objects into the archive. This will slurp in
628 // all of the native libraries of upstream dependencies as well.
630 // Additionally, there's no way for us to link dynamic libraries, so we warn
631 // about all dynamic library dependencies that they're not linked in.
633 // There's no need to include metadata in a static archive, so ensure to not
634 // link in the metadata object file (and also don't prepare the archive with a
636 fn link_staticlib(sess: &Session, objects: &[PathBuf], out_filename: &Path,
638 let mut ab = link_rlib(sess, None, objects, out_filename, tempdir);
639 let mut all_native_libs = vec![];
641 each_linked_rlib(sess, &mut |cnum, path| {
642 let name = sess.cstore.crate_name(cnum);
643 let native_libs = sess.cstore.native_libraries(cnum);
645 // Here when we include the rlib into our staticlib we need to make a
646 // decision whether to include the extra object files along the way.
647 // These extra object files come from statically included native
648 // libraries, but they may be cfg'd away with #[link(cfg(..))].
650 // This unstable feature, though, only needs liblibc to work. The only
651 // use case there is where musl is statically included in liblibc.rlib,
652 // so if we don't want the included version we just need to skip it. As
653 // a result the logic here is that if *any* linked library is cfg'd away
654 // we just skip all object files.
656 // Clearly this is not sufficient for a general purpose feature, and
657 // we'd want to read from the library's metadata to determine which
658 // object files come from where and selectively skip them.
659 let skip_object_files = native_libs.iter().any(|lib| {
660 lib.kind == NativeLibraryKind::NativeStatic && !relevant_lib(sess, lib)
662 ab.add_rlib(path, &name.as_str(), sess.lto(), skip_object_files).unwrap();
664 all_native_libs.extend(sess.cstore.native_libraries(cnum));
670 if !all_native_libs.is_empty() {
671 sess.note_without_error("link against the following native artifacts when linking against \
672 this static library");
673 sess.note_without_error("the order and any duplication can be significant on some \
674 platforms, and so may need to be preserved");
677 for lib in all_native_libs.iter().filter(|l| relevant_lib(sess, l)) {
678 let name = match lib.kind {
679 NativeLibraryKind::NativeStaticNobundle |
680 NativeLibraryKind::NativeUnknown => "library",
681 NativeLibraryKind::NativeFramework => "framework",
682 // These are included, no need to print them
683 NativeLibraryKind::NativeStatic => continue,
685 sess.note_without_error(&format!("{}: {}", name, lib.name));
689 // Create a dynamic library or executable
691 // This will invoke the system linker/cc to create the resulting file. This
692 // links to all upstream files as well.
693 fn link_natively(sess: &Session,
694 crate_type: config::CrateType,
697 trans: &CrateTranslation,
698 outputs: &OutputFilenames,
700 info!("preparing {:?} from {:?} to {:?}", crate_type, objects, out_filename);
702 // The invocations of cc share some flags across platforms
703 let (pname, mut cmd, extra) = get_linker(sess);
704 cmd.env("PATH", command_path(sess, extra));
706 let root = sess.target_filesearch(PathKind::Native).get_lib_path();
707 cmd.args(&sess.target.target.options.pre_link_args);
709 let pre_link_objects = if crate_type == config::CrateTypeExecutable {
710 &sess.target.target.options.pre_link_objects_exe
712 &sess.target.target.options.pre_link_objects_dll
714 for obj in pre_link_objects {
715 cmd.arg(root.join(obj));
718 if sess.target.target.options.is_like_emscripten &&
719 sess.panic_strategy() == PanicStrategy::Abort {
720 cmd.args(&["-s", "DISABLE_EXCEPTION_CATCHING=1"]);
724 let mut linker = trans.linker_info.to_linker(&mut cmd, &sess);
725 link_args(&mut *linker, sess, crate_type, tmpdir,
726 objects, out_filename, outputs, trans);
728 cmd.args(&sess.target.target.options.late_link_args);
729 for obj in &sess.target.target.options.post_link_objects {
730 cmd.arg(root.join(obj));
732 cmd.args(&sess.target.target.options.post_link_args);
734 if sess.opts.debugging_opts.print_link_args {
735 println!("{:?}", &cmd);
738 // May have not found libraries in the right formats.
739 sess.abort_if_errors();
741 // Invoke the system linker
743 let prog = time(sess.time_passes(), "running linker", || cmd.output());
746 fn escape_string(s: &[u8]) -> String {
747 str::from_utf8(s).map(|s| s.to_owned())
748 .unwrap_or_else(|_| {
749 let mut x = "Non-UTF-8 output: ".to_string();
751 .flat_map(|&b| ascii::escape_default(b))
752 .map(|b| char::from_u32(b as u32).unwrap()));
756 if !prog.status.success() {
757 let mut output = prog.stderr.clone();
758 output.extend_from_slice(&prog.stdout);
759 sess.struct_err(&format!("linking with `{}` failed: {}",
762 .note(&format!("{:?}", &cmd))
763 .note(&escape_string(&output[..]))
765 sess.abort_if_errors();
767 info!("linker stderr:\n{}", escape_string(&prog.stderr[..]));
768 info!("linker stdout:\n{}", escape_string(&prog.stdout[..]));
771 sess.struct_err(&format!("could not exec the linker `{}`: {}", pname, e))
772 .note(&format!("{:?}", &cmd))
774 if sess.target.target.options.is_like_msvc && e.kind() == io::ErrorKind::NotFound {
775 sess.note_without_error("the msvc targets depend on the msvc linker \
776 but `link.exe` was not found");
777 sess.note_without_error("please ensure that VS 2013 or VS 2015 was installed \
778 with the Visual C++ option");
780 sess.abort_if_errors();
785 // On OSX, debuggers need this utility to get run to do some munging of
787 if sess.target.target.options.is_like_osx && sess.opts.debuginfo != NoDebugInfo {
788 match Command::new("dsymutil").arg(out_filename).output() {
790 Err(e) => sess.fatal(&format!("failed to run dsymutil: {}", e)),
795 fn link_args(cmd: &mut Linker,
797 crate_type: config::CrateType,
801 outputs: &OutputFilenames,
802 trans: &CrateTranslation) {
804 // The default library location, we need this to find the runtime.
805 // The location of crates will be determined as needed.
806 let lib_path = sess.target_filesearch(PathKind::All).get_lib_path();
809 let t = &sess.target.target;
811 cmd.include_path(&fix_windows_verbatim_for_gcc(&lib_path));
815 cmd.output_filename(out_filename);
817 if crate_type == config::CrateTypeExecutable &&
818 sess.target.target.options.is_like_windows {
819 if let Some(ref s) = trans.windows_subsystem {
824 // If we're building a dynamic library then some platforms need to make sure
825 // that all symbols are exported correctly from the dynamic library.
826 if crate_type != config::CrateTypeExecutable {
827 cmd.export_symbols(tmpdir, crate_type);
830 // When linking a dynamic library, we put the metadata into a section of the
831 // executable. This metadata is in a separate object file from the main
832 // object file, so we link that in here.
833 if crate_type == config::CrateTypeDylib ||
834 crate_type == config::CrateTypeProcMacro {
835 cmd.add_object(&outputs.with_extension("metadata.o"));
838 // Try to strip as much out of the generated object by removing unused
839 // sections if possible. See more comments in linker.rs
840 if !sess.opts.cg.link_dead_code {
841 let keep_metadata = crate_type == config::CrateTypeDylib;
842 cmd.gc_sections(keep_metadata);
845 let used_link_args = sess.cstore.used_link_args();
847 if crate_type == config::CrateTypeExecutable &&
848 t.options.position_independent_executables {
849 let empty_vec = Vec::new();
850 let empty_str = String::new();
851 let args = sess.opts.cg.link_args.as_ref().unwrap_or(&empty_vec);
852 let more_args = &sess.opts.cg.link_arg;
853 let mut args = args.iter().chain(more_args.iter()).chain(used_link_args.iter());
854 let relocation_model = sess.opts.cg.relocation_model.as_ref()
855 .unwrap_or(&empty_str);
856 if (t.options.relocation_model == "pic" || *relocation_model == "pic")
857 && !args.any(|x| *x == "-static") {
858 cmd.position_independent_executable();
862 // Pass optimization flags down to the linker.
865 // Pass debuginfo flags down to the linker.
868 // We want to prevent the compiler from accidentally leaking in any system
869 // libraries, so we explicitly ask gcc to not link to any libraries by
870 // default. Note that this does not happen for windows because windows pulls
871 // in some large number of libraries and I couldn't quite figure out which
873 if t.options.no_default_libraries {
874 cmd.no_default_libraries();
877 // Take careful note of the ordering of the arguments we pass to the linker
878 // here. Linkers will assume that things on the left depend on things to the
879 // right. Things on the right cannot depend on things on the left. This is
880 // all formally implemented in terms of resolving symbols (libs on the right
881 // resolve unknown symbols of libs on the left, but not vice versa).
883 // For this reason, we have organized the arguments we pass to the linker as
886 // 1. The local object that LLVM just generated
887 // 2. Local native libraries
888 // 3. Upstream rust libraries
889 // 4. Upstream native libraries
891 // The rationale behind this ordering is that those items lower down in the
892 // list can't depend on items higher up in the list. For example nothing can
893 // depend on what we just generated (e.g. that'd be a circular dependency).
894 // Upstream rust libraries are not allowed to depend on our local native
895 // libraries as that would violate the structure of the DAG, in that
896 // scenario they are required to link to them as well in a shared fashion.
898 // Note that upstream rust libraries may contain native dependencies as
899 // well, but they also can't depend on what we just started to add to the
900 // link line. And finally upstream native libraries can't depend on anything
901 // in this DAG so far because they're only dylibs and dylibs can only depend
902 // on other dylibs (e.g. other native deps).
903 add_local_native_libraries(cmd, sess);
904 add_upstream_rust_crates(cmd, sess, crate_type, tmpdir);
905 add_upstream_native_libraries(cmd, sess, crate_type);
907 // # Telling the linker what we're doing
909 if crate_type != config::CrateTypeExecutable {
910 cmd.build_dylib(out_filename);
913 // FIXME (#2397): At some point we want to rpath our guesses as to
914 // where extern libraries might live, based on the
915 // addl_lib_search_paths
916 if sess.opts.cg.rpath {
917 let sysroot = sess.sysroot();
918 let target_triple = &sess.opts.target_triple;
919 let mut get_install_prefix_lib_path = || {
920 let install_prefix = option_env!("CFG_PREFIX").expect("CFG_PREFIX");
921 let tlib = filesearch::relative_target_lib_path(sysroot, target_triple);
922 let mut path = PathBuf::from(install_prefix);
927 let mut rpath_config = RPathConfig {
928 used_crates: sess.cstore.used_crates(LinkagePreference::RequireDynamic),
929 out_filename: out_filename.to_path_buf(),
930 has_rpath: sess.target.target.options.has_rpath,
931 is_like_osx: sess.target.target.options.is_like_osx,
932 linker_is_gnu: sess.target.target.options.linker_is_gnu,
933 get_install_prefix_lib_path: &mut get_install_prefix_lib_path,
935 cmd.args(&rpath::get_rpath_flags(&mut rpath_config));
938 // Finally add all the linker arguments provided on the command line along
939 // with any #[link_args] attributes found inside the crate
940 if let Some(ref args) = sess.opts.cg.link_args {
943 cmd.args(&sess.opts.cg.link_arg);
944 cmd.args(&used_link_args);
947 // # Native library linking
949 // User-supplied library search paths (-L on the command line). These are
950 // the same paths used to find Rust crates, so some of them may have been
951 // added already by the previous crate linking code. This only allows them
952 // to be found at compile time so it is still entirely up to outside
953 // forces to make sure that library can be found at runtime.
955 // Also note that the native libraries linked here are only the ones located
956 // in the current crate. Upstream crates with native library dependencies
957 // may have their native library pulled in above.
958 fn add_local_native_libraries(cmd: &mut Linker, sess: &Session) {
959 sess.target_filesearch(PathKind::All).for_each_lib_search_path(|path, k| {
961 PathKind::Framework => { cmd.framework_path(path); }
962 _ => { cmd.include_path(&fix_windows_verbatim_for_gcc(path)); }
966 let pair = sess.cstore.used_libraries().into_iter().filter(|l| {
967 relevant_lib(sess, l)
969 lib.kind == NativeLibraryKind::NativeStatic
971 let (staticlibs, others): (Vec<_>, Vec<_>) = pair;
973 // Some platforms take hints about whether a library is static or dynamic.
974 // For those that support this, we ensure we pass the option if the library
975 // was flagged "static" (most defaults are dynamic) to ensure that if
976 // libfoo.a and libfoo.so both exist that the right one is chosen.
979 let search_path = archive_search_paths(sess);
980 for l in staticlibs {
981 // Here we explicitly ask that the entire archive is included into the
982 // result artifact. For more details see #15460, but the gist is that
983 // the linker will strip away any unused objects in the archive if we
984 // don't otherwise explicitly reference them. This can occur for
985 // libraries which are just providing bindings, libraries with generic
987 cmd.link_whole_staticlib(&l.name.as_str(), &search_path);
994 NativeLibraryKind::NativeUnknown => cmd.link_dylib(&lib.name.as_str()),
995 NativeLibraryKind::NativeFramework => cmd.link_framework(&lib.name.as_str()),
996 NativeLibraryKind::NativeStaticNobundle => cmd.link_staticlib(&lib.name.as_str()),
997 NativeLibraryKind::NativeStatic => bug!(),
1002 // # Rust Crate linking
1004 // Rust crates are not considered at all when creating an rlib output. All
1005 // dependencies will be linked when producing the final output (instead of
1006 // the intermediate rlib version)
1007 fn add_upstream_rust_crates(cmd: &mut Linker,
1009 crate_type: config::CrateType,
1011 // All of the heavy lifting has previously been accomplished by the
1012 // dependency_format module of the compiler. This is just crawling the
1013 // output of that module, adding crates as necessary.
1015 // Linking to a rlib involves just passing it to the linker (the linker
1016 // will slurp up the object files inside), and linking to a dynamic library
1017 // involves just passing the right -l flag.
1019 let formats = sess.dependency_formats.borrow();
1020 let data = formats.get(&crate_type).unwrap();
1022 // Invoke get_used_crates to ensure that we get a topological sorting of
1024 let deps = sess.cstore.used_crates(LinkagePreference::RequireDynamic);
1026 let mut compiler_builtins = None;
1028 for &(cnum, _) in &deps {
1029 // We may not pass all crates through to the linker. Some crates may
1030 // appear statically in an existing dylib, meaning we'll pick up all the
1031 // symbols from the dylib.
1032 let src = sess.cstore.used_crate_source(cnum);
1033 match data[cnum.as_usize() - 1] {
1034 // compiler-builtins are always placed last to ensure that they're
1035 // linked correctly.
1036 _ if sess.cstore.is_compiler_builtins(cnum) => {
1037 assert!(compiler_builtins.is_none());
1038 compiler_builtins = Some(cnum);
1040 Linkage::NotLinked |
1041 Linkage::IncludedFromDylib => {}
1042 Linkage::Static => {
1043 add_static_crate(cmd, sess, tmpdir, crate_type, cnum);
1045 Linkage::Dynamic => {
1046 add_dynamic_crate(cmd, sess, &src.dylib.unwrap().0)
1051 // We must always link the `compiler_builtins` crate statically. Even if it
1052 // was already "included" in a dylib (e.g. `libstd` when `-C prefer-dynamic`
1054 if let Some(cnum) = compiler_builtins {
1055 add_static_crate(cmd, sess, tmpdir, crate_type, cnum);
1058 // Converts a library file-stem into a cc -l argument
1059 fn unlib<'a>(config: &config::Config, stem: &'a str) -> &'a str {
1060 if stem.starts_with("lib") && !config.target.options.is_like_windows {
1067 // Adds the static "rlib" versions of all crates to the command line.
1068 // There's a bit of magic which happens here specifically related to LTO and
1069 // dynamic libraries. Specifically:
1071 // * For LTO, we remove upstream object files.
1072 // * For dylibs we remove metadata and bytecode from upstream rlibs
1074 // When performing LTO, almost(*) all of the bytecode from the upstream
1075 // libraries has already been included in our object file output. As a
1076 // result we need to remove the object files in the upstream libraries so
1077 // the linker doesn't try to include them twice (or whine about duplicate
1078 // symbols). We must continue to include the rest of the rlib, however, as
1079 // it may contain static native libraries which must be linked in.
1081 // (*) Crates marked with `#![no_builtins]` don't participate in LTO and
1082 // their bytecode wasn't included. The object files in those libraries must
1083 // still be passed to the linker.
1085 // When making a dynamic library, linkers by default don't include any
1086 // object files in an archive if they're not necessary to resolve the link.
1087 // We basically want to convert the archive (rlib) to a dylib, though, so we
1088 // *do* want everything included in the output, regardless of whether the
1089 // linker thinks it's needed or not. As a result we must use the
1090 // --whole-archive option (or the platform equivalent). When using this
1091 // option the linker will fail if there are non-objects in the archive (such
1092 // as our own metadata and/or bytecode). All in all, for rlibs to be
1093 // entirely included in dylibs, we need to remove all non-object files.
1095 // Note, however, that if we're not doing LTO or we're not producing a dylib
1096 // (aka we're making an executable), we can just pass the rlib blindly to
1097 // the linker (fast) because it's fine if it's not actually included as
1098 // we're at the end of the dependency chain.
1099 fn add_static_crate(cmd: &mut Linker,
1102 crate_type: config::CrateType,
1104 let src = sess.cstore.used_crate_source(cnum);
1105 let cratepath = &src.rlib.unwrap().0;
1107 // See the comment above in `link_staticlib` and `link_rlib` for why if
1108 // there's a static library that's not relevant we skip all object
1110 let native_libs = sess.cstore.native_libraries(cnum);
1111 let skip_native = native_libs.iter().any(|lib| {
1112 lib.kind == NativeLibraryKind::NativeStatic && !relevant_lib(sess, lib)
1115 if !sess.lto() && crate_type != config::CrateTypeDylib && !skip_native {
1116 cmd.link_rlib(&fix_windows_verbatim_for_gcc(cratepath));
1120 let dst = tmpdir.join(cratepath.file_name().unwrap());
1121 let name = cratepath.file_name().unwrap().to_str().unwrap();
1122 let name = &name[3..name.len() - 5]; // chop off lib/.rlib
1124 time(sess.time_passes(), &format!("altering {}.rlib", name), || {
1125 let cfg = archive_config(sess, &dst, Some(cratepath));
1126 let mut archive = ArchiveBuilder::new(cfg);
1127 archive.update_symbols();
1129 let mut any_objects = false;
1130 for f in archive.src_files() {
1131 if f.ends_with("bytecode.deflate") ||
1132 f == sess.cstore.metadata_filename() {
1133 archive.remove_file(&f);
1137 let canonical = f.replace("-", "_");
1138 let canonical_name = name.replace("-", "_");
1140 let is_rust_object =
1141 canonical.starts_with(&canonical_name) && {
1142 let num = &f[name.len()..f.len() - 2];
1143 num.len() > 0 && num[1..].parse::<u32>().is_ok()
1146 // If we've been requested to skip all native object files
1147 // (those not generated by the rust compiler) then we can skip
1148 // this file. See above for why we may want to do this.
1149 let skip_because_cfg_say_so = skip_native && !is_rust_object;
1151 // If we're performing LTO and this is a rust-generated object
1152 // file, then we don't need the object file as it's part of the
1153 // LTO module. Note that `#![no_builtins]` is excluded from LTO,
1154 // though, so we let that object file slide.
1155 let skip_because_lto = sess.lto() && is_rust_object &&
1156 !sess.cstore.is_no_builtins(cnum);
1158 if skip_because_cfg_say_so || skip_because_lto {
1159 archive.remove_file(&f);
1170 // If we're creating a dylib, then we need to include the
1171 // whole of each object in our archive into that artifact. This is
1172 // because a `dylib` can be reused as an intermediate artifact.
1174 // Note, though, that we don't want to include the whole of a
1175 // compiler-builtins crate (e.g. compiler-rt) because it'll get
1176 // repeatedly linked anyway.
1177 if crate_type == config::CrateTypeDylib &&
1178 !sess.cstore.is_compiler_builtins(cnum) {
1179 cmd.link_whole_rlib(&fix_windows_verbatim_for_gcc(&dst));
1181 cmd.link_rlib(&fix_windows_verbatim_for_gcc(&dst));
1186 // Same thing as above, but for dynamic crates instead of static crates.
1187 fn add_dynamic_crate(cmd: &mut Linker, sess: &Session, cratepath: &Path) {
1188 // If we're performing LTO, then it should have been previously required
1189 // that all upstream rust dependencies were available in an rlib format.
1190 assert!(!sess.lto());
1192 // Just need to tell the linker about where the library lives and
1194 let parent = cratepath.parent();
1195 if let Some(dir) = parent {
1196 cmd.include_path(&fix_windows_verbatim_for_gcc(dir));
1198 let filestem = cratepath.file_stem().unwrap().to_str().unwrap();
1199 cmd.link_rust_dylib(&unlib(&sess.target, filestem),
1200 parent.unwrap_or(Path::new("")));
1204 // Link in all of our upstream crates' native dependencies. Remember that
1205 // all of these upstream native dependencies are all non-static
1206 // dependencies. We've got two cases then:
1208 // 1. The upstream crate is an rlib. In this case we *must* link in the
1209 // native dependency because the rlib is just an archive.
1211 // 2. The upstream crate is a dylib. In order to use the dylib, we have to
1212 // have the dependency present on the system somewhere. Thus, we don't
1213 // gain a whole lot from not linking in the dynamic dependency to this
1216 // The use case for this is a little subtle. In theory the native
1217 // dependencies of a crate are purely an implementation detail of the crate
1218 // itself, but the problem arises with generic and inlined functions. If a
1219 // generic function calls a native function, then the generic function must
1220 // be instantiated in the target crate, meaning that the native symbol must
1221 // also be resolved in the target crate.
1222 fn add_upstream_native_libraries(cmd: &mut Linker, sess: &Session, crate_type: config::CrateType) {
1223 // Be sure to use a topological sorting of crates because there may be
1224 // interdependencies between native libraries. When passing -nodefaultlibs,
1225 // for example, almost all native libraries depend on libc, so we have to
1226 // make sure that's all the way at the right (liblibc is near the base of
1227 // the dependency chain).
1229 // This passes RequireStatic, but the actual requirement doesn't matter,
1230 // we're just getting an ordering of crate numbers, we're not worried about
1232 let formats = sess.dependency_formats.borrow();
1233 let data = formats.get(&crate_type).unwrap();
1235 let crates = sess.cstore.used_crates(LinkagePreference::RequireStatic);
1236 for (cnum, _) in crates {
1237 for lib in sess.cstore.native_libraries(cnum) {
1238 if !relevant_lib(sess, &lib) {
1242 NativeLibraryKind::NativeUnknown => cmd.link_dylib(&lib.name.as_str()),
1243 NativeLibraryKind::NativeFramework => cmd.link_framework(&lib.name.as_str()),
1244 NativeLibraryKind::NativeStaticNobundle => {
1245 // Link "static-nobundle" native libs only if the crate they originate from
1246 // is being linked statically to the current crate. If it's linked dynamically
1247 // or is an rlib already included via some other dylib crate, the symbols from
1248 // native libs will have already been included in that dylib.
1249 if data[cnum.as_usize() - 1] == Linkage::Static {
1250 cmd.link_staticlib(&lib.name.as_str())
1253 // ignore statically included native libraries here as we've
1254 // already included them when we included the rust library
1256 NativeLibraryKind::NativeStatic => {}
1262 fn relevant_lib(sess: &Session, lib: &NativeLibrary) -> bool {
1264 Some(ref cfg) => attr::cfg_matches(cfg, &sess.parse_sess, None),