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};
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::svh::Svh;
30 use rustc_back::tempdir::TempDir;
31 use rustc_incremental::IncrementalHashesMap;
36 use std::ffi::OsString;
38 use std::io::{self, Read, Write};
40 use std::path::{Path, PathBuf};
41 use std::process::Command;
45 use syntax::attr::AttrMetaMethods;
48 // RLIB LLVM-BYTECODE OBJECT LAYOUT
51 // 0..10 "RUST_OBJECT" encoded in ASCII
52 // 11..14 format version as little-endian u32
53 // 15..22 size in bytes of deflate compressed LLVM bitcode as
55 // 23.. compressed LLVM bitcode
57 // This is the "magic number" expected at the beginning of a LLVM bytecode
59 pub const RLIB_BYTECODE_OBJECT_MAGIC: &'static [u8] = b"RUST_OBJECT";
61 // The version number this compiler will write to bytecode objects in rlibs
62 pub const RLIB_BYTECODE_OBJECT_VERSION: u32 = 1;
64 // The offset in bytes the bytecode object format version number can be found at
65 pub const RLIB_BYTECODE_OBJECT_VERSION_OFFSET: usize = 11;
67 // The offset in bytes the size of the compressed bytecode can be found at in
69 pub const RLIB_BYTECODE_OBJECT_V1_DATASIZE_OFFSET: usize =
70 RLIB_BYTECODE_OBJECT_VERSION_OFFSET + 4;
72 // The offset in bytes the compressed LLVM bytecode can be found at in format
74 pub const RLIB_BYTECODE_OBJECT_V1_DATA_OFFSET: usize =
75 RLIB_BYTECODE_OBJECT_V1_DATASIZE_OFFSET + 8;
78 pub fn find_crate_name(sess: Option<&Session>,
79 attrs: &[ast::Attribute],
80 input: &Input) -> String {
81 let validate = |s: String, span: Option<Span>| {
82 cstore::validate_crate_name(sess, &s[..], span);
86 // Look in attributes 100% of the time to make sure the attribute is marked
87 // as used. After doing this, however, we still prioritize a crate name from
88 // the command line over one found in the #[crate_name] attribute. If we
89 // find both we ensure that they're the same later on as well.
90 let attr_crate_name = attrs.iter().find(|at| at.check_name("crate_name"))
91 .and_then(|at| at.value_str().map(|s| (at, s)));
93 if let Some(sess) = sess {
94 if let Some(ref s) = sess.opts.crate_name {
95 if let Some((attr, ref name)) = attr_crate_name {
97 let msg = format!("--crate-name and #[crate_name] are \
98 required to match, but `{}` != `{}`",
100 sess.span_err(attr.span, &msg[..]);
103 return validate(s.clone(), None);
107 if let Some((attr, s)) = attr_crate_name {
108 return validate(s.to_string(), Some(attr.span));
110 if let Input::File(ref path) = *input {
111 if let Some(s) = path.file_stem().and_then(|s| s.to_str()) {
112 if s.starts_with("-") {
113 let msg = format!("crate names cannot start with a `-`, but \
114 `{}` has a leading hyphen", s);
115 if let Some(sess) = sess {
119 return validate(s.replace("-", "_"), None);
124 "rust_out".to_string()
128 pub fn build_link_meta(incremental_hashes_map: &IncrementalHashesMap,
132 crate_name: name.to_owned(),
133 crate_hash: Svh::new(incremental_hashes_map[&DepNode::Krate]),
139 // The third parameter is for an extra path to add to PATH for MSVC
140 // cross linkers for host toolchain DLL dependencies
141 pub fn get_linker(sess: &Session) -> (String, Command, Option<PathBuf>) {
142 if let Some(ref linker) = sess.opts.cg.linker {
143 (linker.clone(), Command::new(linker), None)
144 } else if sess.target.target.options.is_like_msvc {
145 let (cmd, host) = msvc::link_exe_cmd(sess);
146 ("link.exe".to_string(), cmd, host)
148 (sess.target.target.options.linker.clone(),
149 Command::new(&sess.target.target.options.linker), None)
153 pub fn get_ar_prog(sess: &Session) -> String {
154 sess.opts.cg.ar.clone().unwrap_or_else(|| {
155 sess.target.target.options.ar.clone()
159 fn command_path(sess: &Session, extra: Option<PathBuf>) -> OsString {
160 // The compiler's sysroot often has some bundled tools, so add it to the
161 // PATH for the child.
162 let mut new_path = sess.host_filesearch(PathKind::All)
163 .get_tools_search_paths();
164 if let Some(path) = env::var_os("PATH") {
165 new_path.extend(env::split_paths(&path));
167 new_path.extend(extra);
168 env::join_paths(new_path).unwrap()
171 pub fn remove(sess: &Session, path: &Path) {
172 match fs::remove_file(path) {
175 sess.err(&format!("failed to remove {}: {}",
182 /// Perform the linkage portion of the compilation phase. This will generate all
183 /// of the requested outputs for this compilation session.
184 pub fn link_binary(sess: &Session,
185 trans: &CrateTranslation,
186 outputs: &OutputFilenames,
187 crate_name: &str) -> Vec<PathBuf> {
188 let _task = sess.dep_graph.in_task(DepNode::LinkBinary);
190 let mut out_filenames = Vec::new();
191 for &crate_type in sess.crate_types.borrow().iter() {
192 // Ignore executable crates if we have -Z no-trans, as they will error.
193 if sess.opts.debugging_opts.no_trans &&
194 crate_type == config::CrateTypeExecutable {
198 if invalid_output_for_target(sess, crate_type) {
199 bug!("invalid output type `{:?}` for target os `{}`",
200 crate_type, sess.opts.target_triple);
202 let out_file = link_binary_output(sess, trans, crate_type, outputs,
204 out_filenames.push(out_file);
207 // Remove the temporary object file and metadata if we aren't saving temps
208 if !sess.opts.cg.save_temps {
209 for obj in object_filenames(trans, outputs) {
212 remove(sess, &outputs.with_extension("metadata.o"));
219 /// Returns default crate type for target
221 /// Default crate type is used when crate type isn't provided neither
222 /// through cmd line arguments nor through crate attributes
224 /// It is CrateTypeExecutable for all platforms but iOS as there is no
225 /// way to run iOS binaries anyway without jailbreaking and
226 /// interaction with Rust code through static library is the only
228 pub fn default_output_for_target(sess: &Session) -> config::CrateType {
229 if !sess.target.target.options.executables {
230 config::CrateTypeStaticlib
232 config::CrateTypeExecutable
236 /// Checks if target supports crate_type as output
237 pub fn invalid_output_for_target(sess: &Session,
238 crate_type: config::CrateType) -> bool {
239 match (sess.target.target.options.dynamic_linking,
240 sess.target.target.options.executables, crate_type) {
241 (false, _, config::CrateTypeCdylib) |
242 (false, _, config::CrateTypeDylib) => true,
243 (_, false, config::CrateTypeExecutable) => true,
248 fn is_writeable(p: &Path) -> bool {
251 Ok(m) => !m.permissions().readonly()
255 pub fn filename_for_input(sess: &Session,
256 crate_type: config::CrateType,
258 outputs: &OutputFilenames) -> PathBuf {
259 let libname = format!("{}{}", crate_name, sess.opts.cg.extra_filename);
261 config::CrateTypeRlib => {
262 outputs.out_directory.join(&format!("lib{}.rlib", libname))
264 config::CrateTypeCdylib |
265 config::CrateTypeDylib => {
266 let (prefix, suffix) = (&sess.target.target.options.dll_prefix,
267 &sess.target.target.options.dll_suffix);
268 outputs.out_directory.join(&format!("{}{}{}", prefix, libname,
271 config::CrateTypeStaticlib => {
272 let (prefix, suffix) = (&sess.target.target.options.staticlib_prefix,
273 &sess.target.target.options.staticlib_suffix);
274 outputs.out_directory.join(&format!("{}{}{}", prefix, libname,
277 config::CrateTypeExecutable => {
278 let suffix = &sess.target.target.options.exe_suffix;
279 let out_filename = outputs.path(OutputType::Exe);
280 if suffix.is_empty() {
281 out_filename.to_path_buf()
283 out_filename.with_extension(&suffix[1..])
289 pub fn each_linked_rlib(sess: &Session,
290 f: &mut FnMut(ast::CrateNum, &Path)) {
291 let crates = sess.cstore.used_crates(LinkagePreference::RequireStatic).into_iter();
292 let fmts = sess.dependency_formats.borrow();
293 let fmts = fmts.get(&config::CrateTypeExecutable)
294 .or_else(|| fmts.get(&config::CrateTypeStaticlib))
295 .or_else(|| fmts.get(&config::CrateTypeCdylib));
296 let fmts = fmts.unwrap_or_else(|| {
297 bug!("could not find formats for rlibs")
299 for (cnum, path) in crates {
300 match fmts[cnum as usize - 1] {
301 Linkage::NotLinked | Linkage::IncludedFromDylib => continue,
304 let name = sess.cstore.crate_name(cnum).clone();
305 let path = match path {
308 sess.fatal(&format!("could not find rlib for: `{}`", name));
315 fn link_binary_output(sess: &Session,
316 trans: &CrateTranslation,
317 crate_type: config::CrateType,
318 outputs: &OutputFilenames,
319 crate_name: &str) -> PathBuf {
320 let objects = object_filenames(trans, outputs);
321 let default_filename = filename_for_input(sess, crate_type, crate_name,
323 let out_filename = outputs.outputs.get(&OutputType::Exe)
324 .and_then(|s| s.to_owned())
325 .or_else(|| outputs.single_output_file.clone())
326 .unwrap_or(default_filename);
328 // Make sure files are writeable. Mac, FreeBSD, and Windows system linkers
329 // check this already -- however, the Linux linker will happily overwrite a
330 // read-only file. We should be consistent.
331 for file in objects.iter().chain(Some(&out_filename)) {
332 if !is_writeable(file) {
333 sess.fatal(&format!("output file {} is not writeable -- check its \
334 permissions", file.display()));
338 let tmpdir = match TempDir::new("rustc") {
339 Ok(tmpdir) => tmpdir,
340 Err(err) => sess.fatal(&format!("couldn't create a temp dir: {}", err)),
344 config::CrateTypeRlib => {
345 link_rlib(sess, Some(trans), &objects, &out_filename,
346 tmpdir.path()).build();
348 config::CrateTypeStaticlib => {
349 link_staticlib(sess, &objects, &out_filename, tmpdir.path());
352 link_natively(sess, crate_type, &objects, &out_filename, trans,
353 outputs, tmpdir.path());
360 fn object_filenames(trans: &CrateTranslation,
361 outputs: &OutputFilenames)
363 trans.modules.iter().map(|module| {
364 outputs.temp_path(OutputType::Object, Some(&module.name[..]))
368 fn archive_search_paths(sess: &Session) -> Vec<PathBuf> {
369 let mut search = Vec::new();
370 sess.target_filesearch(PathKind::Native).for_each_lib_search_path(|path, _| {
371 search.push(path.to_path_buf());
376 fn archive_config<'a>(sess: &'a Session,
378 input: Option<&Path>) -> ArchiveConfig<'a> {
381 dst: output.to_path_buf(),
382 src: input.map(|p| p.to_path_buf()),
383 lib_search_paths: archive_search_paths(sess),
384 ar_prog: get_ar_prog(sess),
385 command_path: command_path(sess, None),
391 // An rlib in its current incarnation is essentially a renamed .a file. The
392 // rlib primarily contains the object file of the crate, but it also contains
393 // all of the object files from native libraries. This is done by unzipping
394 // native libraries and inserting all of the contents into this archive.
395 fn link_rlib<'a>(sess: &'a Session,
396 trans: Option<&CrateTranslation>, // None == no metadata/bytecode
399 tmpdir: &Path) -> ArchiveBuilder<'a> {
400 info!("preparing rlib from {:?} to {:?}", objects, out_filename);
401 let mut ab = ArchiveBuilder::new(archive_config(sess, out_filename, None));
406 for (l, kind) in sess.cstore.used_libraries() {
408 NativeLibraryKind::NativeStatic => ab.add_native_library(&l),
409 NativeLibraryKind::NativeFramework |
410 NativeLibraryKind::NativeUnknown => {}
414 // After adding all files to the archive, we need to update the
415 // symbol table of the archive.
418 // Note that it is important that we add all of our non-object "magical
419 // files" *after* all of the object files in the archive. The reason for
420 // this is as follows:
422 // * When performing LTO, this archive will be modified to remove
423 // objects from above. The reason for this is described below.
425 // * When the system linker looks at an archive, it will attempt to
426 // determine the architecture of the archive in order to see whether its
429 // The algorithm for this detection is: iterate over the files in the
430 // archive. Skip magical SYMDEF names. Interpret the first file as an
431 // object file. Read architecture from the object file.
433 // * As one can probably see, if "metadata" and "foo.bc" were placed
434 // before all of the objects, then the architecture of this archive would
435 // not be correctly inferred once 'foo.o' is removed.
437 // Basically, all this means is that this code should not move above the
441 // Instead of putting the metadata in an object file section, rlibs
442 // contain the metadata in a separate file. We use a temp directory
443 // here so concurrent builds in the same directory don't try to use
444 // the same filename for metadata (stomping over one another)
445 let metadata = tmpdir.join(sess.cstore.metadata_filename());
446 match fs::File::create(&metadata).and_then(|mut f| {
447 f.write_all(&trans.metadata)
451 sess.fatal(&format!("failed to write {}: {}",
452 metadata.display(), e));
455 ab.add_file(&metadata);
457 // For LTO purposes, the bytecode of this library is also inserted
458 // into the archive. If codegen_units > 1, we insert each of the
461 // Note that we make sure that the bytecode filename in the
462 // archive is never exactly 16 bytes long by adding a 16 byte
463 // extension to it. This is to work around a bug in LLDB that
464 // would cause it to crash if the name of a file in an archive
465 // was exactly 16 bytes.
466 let bc_filename = obj.with_extension("bc");
467 let bc_deflated_filename = tmpdir.join({
468 obj.with_extension("bytecode.deflate").file_name().unwrap()
471 let mut bc_data = Vec::new();
472 match fs::File::open(&bc_filename).and_then(|mut f| {
473 f.read_to_end(&mut bc_data)
476 Err(e) => sess.fatal(&format!("failed to read bytecode: {}",
480 let bc_data_deflated = flate::deflate_bytes(&bc_data[..]);
482 let mut bc_file_deflated = match fs::File::create(&bc_deflated_filename) {
485 sess.fatal(&format!("failed to create compressed \
486 bytecode file: {}", e))
490 match write_rlib_bytecode_object_v1(&mut bc_file_deflated,
494 sess.fatal(&format!("failed to write compressed \
499 ab.add_file(&bc_deflated_filename);
501 // See the bottom of back::write::run_passes for an explanation
502 // of when we do and don't keep .#module-name#.bc files around.
503 let user_wants_numbered_bitcode =
504 sess.opts.output_types.contains_key(&OutputType::Bitcode) &&
505 sess.opts.cg.codegen_units > 1;
506 if !sess.opts.cg.save_temps && !user_wants_numbered_bitcode {
507 remove(sess, &bc_filename);
511 // After adding all files to the archive, we need to update the
512 // symbol table of the archive. This currently dies on OSX (see
513 // #11162), and isn't necessary there anyway
514 if !sess.target.target.options.is_like_osx {
525 fn write_rlib_bytecode_object_v1(writer: &mut Write,
526 bc_data_deflated: &[u8]) -> io::Result<()> {
527 let bc_data_deflated_size: u64 = bc_data_deflated.len() as u64;
529 writer.write_all(RLIB_BYTECODE_OBJECT_MAGIC)?;
530 writer.write_all(&[1, 0, 0, 0])?;
532 (bc_data_deflated_size >> 0) as u8,
533 (bc_data_deflated_size >> 8) as u8,
534 (bc_data_deflated_size >> 16) as u8,
535 (bc_data_deflated_size >> 24) as u8,
536 (bc_data_deflated_size >> 32) as u8,
537 (bc_data_deflated_size >> 40) as u8,
538 (bc_data_deflated_size >> 48) as u8,
539 (bc_data_deflated_size >> 56) as u8,
541 writer.write_all(&bc_data_deflated)?;
543 let number_of_bytes_written_so_far =
544 RLIB_BYTECODE_OBJECT_MAGIC.len() + // magic id
545 mem::size_of_val(&RLIB_BYTECODE_OBJECT_VERSION) + // version
546 mem::size_of_val(&bc_data_deflated_size) + // data size field
547 bc_data_deflated_size as usize; // actual data
549 // If the number of bytes written to the object so far is odd, add a
550 // padding byte to make it even. This works around a crash bug in LLDB
551 // (see issue #15950)
552 if number_of_bytes_written_so_far % 2 == 1 {
553 writer.write_all(&[0])?;
559 // Create a static archive
561 // This is essentially the same thing as an rlib, but it also involves adding
562 // all of the upstream crates' objects into the archive. This will slurp in
563 // all of the native libraries of upstream dependencies as well.
565 // Additionally, there's no way for us to link dynamic libraries, so we warn
566 // about all dynamic library dependencies that they're not linked in.
568 // There's no need to include metadata in a static archive, so ensure to not
569 // link in the metadata object file (and also don't prepare the archive with a
571 fn link_staticlib(sess: &Session, objects: &[PathBuf], out_filename: &Path,
573 let mut ab = link_rlib(sess, None, objects, out_filename, tempdir);
574 if !sess.target.target.options.no_compiler_rt {
575 ab.add_native_library("compiler-rt");
578 let mut all_native_libs = vec![];
580 each_linked_rlib(sess, &mut |cnum, path| {
581 let name = sess.cstore.crate_name(cnum);
582 ab.add_rlib(path, &name, sess.lto()).unwrap();
584 let native_libs = sess.cstore.native_libraries(cnum);
585 all_native_libs.extend(native_libs);
591 if !all_native_libs.is_empty() {
592 sess.note_without_error("link against the following native artifacts when linking against \
593 this static library");
594 sess.note_without_error("the order and any duplication can be significant on some \
595 platforms, and so may need to be preserved");
598 for &(kind, ref lib) in &all_native_libs {
599 let name = match kind {
600 NativeLibraryKind::NativeStatic => "static library",
601 NativeLibraryKind::NativeUnknown => "library",
602 NativeLibraryKind::NativeFramework => "framework",
604 sess.note_without_error(&format!("{}: {}", name, *lib));
608 // Create a dynamic library or executable
610 // This will invoke the system linker/cc to create the resulting file. This
611 // links to all upstream files as well.
612 fn link_natively(sess: &Session,
613 crate_type: config::CrateType,
616 trans: &CrateTranslation,
617 outputs: &OutputFilenames,
619 info!("preparing {:?} from {:?} to {:?}", crate_type, objects, out_filename);
621 // The invocations of cc share some flags across platforms
622 let (pname, mut cmd, extra) = get_linker(sess);
623 cmd.env("PATH", command_path(sess, extra));
625 let root = sess.target_filesearch(PathKind::Native).get_lib_path();
626 cmd.args(&sess.target.target.options.pre_link_args);
628 let pre_link_objects = if crate_type == config::CrateTypeExecutable {
629 &sess.target.target.options.pre_link_objects_exe
631 &sess.target.target.options.pre_link_objects_dll
633 for obj in pre_link_objects {
634 cmd.arg(root.join(obj));
638 let mut linker = trans.linker_info.to_linker(&mut cmd, &sess);
639 link_args(&mut *linker, sess, crate_type, tmpdir,
640 objects, out_filename, outputs);
641 if !sess.target.target.options.no_compiler_rt {
642 linker.link_staticlib("compiler-rt");
645 cmd.args(&sess.target.target.options.late_link_args);
646 for obj in &sess.target.target.options.post_link_objects {
647 cmd.arg(root.join(obj));
649 cmd.args(&sess.target.target.options.post_link_args);
651 if sess.opts.debugging_opts.print_link_args {
652 println!("{:?}", &cmd);
655 // May have not found libraries in the right formats.
656 sess.abort_if_errors();
658 // Invoke the system linker
660 let prog = time(sess.time_passes(), "running linker", || cmd.output());
663 fn escape_string(s: &[u8]) -> String {
664 str::from_utf8(s).map(|s| s.to_owned())
665 .unwrap_or_else(|_| {
666 let mut x = "Non-UTF-8 output: ".to_string();
668 .flat_map(|&b| ascii::escape_default(b))
669 .map(|b| char::from_u32(b as u32).unwrap()));
673 if !prog.status.success() {
674 let mut output = prog.stderr.clone();
675 output.extend_from_slice(&prog.stdout);
676 sess.struct_err(&format!("linking with `{}` failed: {}",
679 .note(&format!("{:?}", &cmd))
680 .note(&escape_string(&output[..]))
682 sess.abort_if_errors();
684 info!("linker stderr:\n{}", escape_string(&prog.stderr[..]));
685 info!("linker stdout:\n{}", escape_string(&prog.stdout[..]));
688 sess.struct_err(&format!("could not exec the linker `{}`: {}", pname, e))
689 .note(&format!("{:?}", &cmd))
691 if sess.target.target.options.is_like_msvc && e.kind() == io::ErrorKind::NotFound {
692 sess.note_without_error("the msvc targets depend on the msvc linker \
693 but `link.exe` was not found");
694 sess.note_without_error("please ensure that VS 2013 or VS 2015 was installed \
695 with the Visual C++ option");
697 sess.abort_if_errors();
702 // On OSX, debuggers need this utility to get run to do some munging of
704 if sess.target.target.options.is_like_osx && sess.opts.debuginfo != NoDebugInfo {
705 match Command::new("dsymutil").arg(out_filename).output() {
707 Err(e) => sess.fatal(&format!("failed to run dsymutil: {}", e)),
712 fn link_args(cmd: &mut Linker,
714 crate_type: config::CrateType,
718 outputs: &OutputFilenames) {
720 // The default library location, we need this to find the runtime.
721 // The location of crates will be determined as needed.
722 let lib_path = sess.target_filesearch(PathKind::All).get_lib_path();
725 let t = &sess.target.target;
727 cmd.include_path(&fix_windows_verbatim_for_gcc(&lib_path));
731 cmd.output_filename(out_filename);
733 // If we're building a dynamic library then some platforms need to make sure
734 // that all symbols are exported correctly from the dynamic library.
735 if crate_type != config::CrateTypeExecutable {
736 cmd.export_symbols(tmpdir, crate_type);
739 // When linking a dynamic library, we put the metadata into a section of the
740 // executable. This metadata is in a separate object file from the main
741 // object file, so we link that in here.
742 if crate_type == config::CrateTypeDylib {
743 cmd.add_object(&outputs.with_extension("metadata.o"));
746 // Try to strip as much out of the generated object by removing unused
747 // sections if possible. See more comments in linker.rs
748 if !sess.opts.cg.link_dead_code {
749 let keep_metadata = crate_type == config::CrateTypeDylib;
750 cmd.gc_sections(keep_metadata);
753 let used_link_args = sess.cstore.used_link_args();
755 if crate_type == config::CrateTypeExecutable &&
756 t.options.position_independent_executables {
757 let empty_vec = Vec::new();
758 let empty_str = String::new();
759 let args = sess.opts.cg.link_args.as_ref().unwrap_or(&empty_vec);
760 let mut args = args.iter().chain(used_link_args.iter());
761 let relocation_model = sess.opts.cg.relocation_model.as_ref()
762 .unwrap_or(&empty_str);
763 if (t.options.relocation_model == "pic" || *relocation_model == "pic")
764 && !args.any(|x| *x == "-static") {
765 cmd.position_independent_executable();
769 // Pass optimization flags down to the linker.
772 // Pass debuginfo flags down to the linker.
775 // We want to prevent the compiler from accidentally leaking in any system
776 // libraries, so we explicitly ask gcc to not link to any libraries by
777 // default. Note that this does not happen for windows because windows pulls
778 // in some large number of libraries and I couldn't quite figure out which
780 if t.options.no_default_libraries {
781 cmd.no_default_libraries();
784 // Take careful note of the ordering of the arguments we pass to the linker
785 // here. Linkers will assume that things on the left depend on things to the
786 // right. Things on the right cannot depend on things on the left. This is
787 // all formally implemented in terms of resolving symbols (libs on the right
788 // resolve unknown symbols of libs on the left, but not vice versa).
790 // For this reason, we have organized the arguments we pass to the linker as
793 // 1. The local object that LLVM just generated
794 // 2. Local native libraries
795 // 3. Upstream rust libraries
796 // 4. Upstream native libraries
798 // The rationale behind this ordering is that those items lower down in the
799 // list can't depend on items higher up in the list. For example nothing can
800 // depend on what we just generated (e.g. that'd be a circular dependency).
801 // Upstream rust libraries are not allowed to depend on our local native
802 // libraries as that would violate the structure of the DAG, in that
803 // scenario they are required to link to them as well in a shared fashion.
805 // Note that upstream rust libraries may contain native dependencies as
806 // well, but they also can't depend on what we just started to add to the
807 // link line. And finally upstream native libraries can't depend on anything
808 // in this DAG so far because they're only dylibs and dylibs can only depend
809 // on other dylibs (e.g. other native deps).
810 add_local_native_libraries(cmd, sess);
811 add_upstream_rust_crates(cmd, sess, crate_type, tmpdir);
812 add_upstream_native_libraries(cmd, sess);
814 // # Telling the linker what we're doing
816 if crate_type != config::CrateTypeExecutable {
817 cmd.build_dylib(out_filename);
820 // FIXME (#2397): At some point we want to rpath our guesses as to
821 // where extern libraries might live, based on the
822 // addl_lib_search_paths
823 if sess.opts.cg.rpath {
824 let sysroot = sess.sysroot();
825 let target_triple = &sess.opts.target_triple;
826 let mut get_install_prefix_lib_path = || {
827 let install_prefix = option_env!("CFG_PREFIX").expect("CFG_PREFIX");
828 let tlib = filesearch::relative_target_lib_path(sysroot, target_triple);
829 let mut path = PathBuf::from(install_prefix);
834 let mut rpath_config = RPathConfig {
835 used_crates: sess.cstore.used_crates(LinkagePreference::RequireDynamic),
836 out_filename: out_filename.to_path_buf(),
837 has_rpath: sess.target.target.options.has_rpath,
838 is_like_osx: sess.target.target.options.is_like_osx,
839 linker_is_gnu: sess.target.target.options.linker_is_gnu,
840 get_install_prefix_lib_path: &mut get_install_prefix_lib_path,
842 cmd.args(&rpath::get_rpath_flags(&mut rpath_config));
845 // Finally add all the linker arguments provided on the command line along
846 // with any #[link_args] attributes found inside the crate
847 if let Some(ref args) = sess.opts.cg.link_args {
850 cmd.args(&used_link_args);
853 // # Native library linking
855 // User-supplied library search paths (-L on the command line). These are
856 // the same paths used to find Rust crates, so some of them may have been
857 // added already by the previous crate linking code. This only allows them
858 // to be found at compile time so it is still entirely up to outside
859 // forces to make sure that library can be found at runtime.
861 // Also note that the native libraries linked here are only the ones located
862 // in the current crate. Upstream crates with native library dependencies
863 // may have their native library pulled in above.
864 fn add_local_native_libraries(cmd: &mut Linker, sess: &Session) {
865 sess.target_filesearch(PathKind::All).for_each_lib_search_path(|path, k| {
867 PathKind::Framework => { cmd.framework_path(path); }
868 _ => { cmd.include_path(&fix_windows_verbatim_for_gcc(path)); }
872 let libs = sess.cstore.used_libraries();
874 let staticlibs = libs.iter().filter_map(|&(ref l, kind)| {
875 if kind == NativeLibraryKind::NativeStatic {Some(l)} else {None}
877 let others = libs.iter().filter(|&&(_, kind)| {
878 kind != NativeLibraryKind::NativeStatic
881 // Some platforms take hints about whether a library is static or dynamic.
882 // For those that support this, we ensure we pass the option if the library
883 // was flagged "static" (most defaults are dynamic) to ensure that if
884 // libfoo.a and libfoo.so both exist that the right one is chosen.
887 let search_path = archive_search_paths(sess);
888 for l in staticlibs {
889 // Here we explicitly ask that the entire archive is included into the
890 // result artifact. For more details see #15460, but the gist is that
891 // the linker will strip away any unused objects in the archive if we
892 // don't otherwise explicitly reference them. This can occur for
893 // libraries which are just providing bindings, libraries with generic
895 cmd.link_whole_staticlib(l, &search_path);
900 for &(ref l, kind) in others {
902 NativeLibraryKind::NativeUnknown => cmd.link_dylib(l),
903 NativeLibraryKind::NativeFramework => cmd.link_framework(l),
904 NativeLibraryKind::NativeStatic => bug!(),
909 // # Rust Crate linking
911 // Rust crates are not considered at all when creating an rlib output. All
912 // dependencies will be linked when producing the final output (instead of
913 // the intermediate rlib version)
914 fn add_upstream_rust_crates(cmd: &mut Linker,
916 crate_type: config::CrateType,
918 // All of the heavy lifting has previously been accomplished by the
919 // dependency_format module of the compiler. This is just crawling the
920 // output of that module, adding crates as necessary.
922 // Linking to a rlib involves just passing it to the linker (the linker
923 // will slurp up the object files inside), and linking to a dynamic library
924 // involves just passing the right -l flag.
926 let formats = sess.dependency_formats.borrow();
927 let data = formats.get(&crate_type).unwrap();
929 // Invoke get_used_crates to ensure that we get a topological sorting of
931 let deps = sess.cstore.used_crates(LinkagePreference::RequireDynamic);
933 for &(cnum, _) in &deps {
934 // We may not pass all crates through to the linker. Some crates may
935 // appear statically in an existing dylib, meaning we'll pick up all the
936 // symbols from the dylib.
937 let src = sess.cstore.used_crate_source(cnum);
938 match data[cnum as usize - 1] {
940 Linkage::IncludedFromDylib => {}
942 add_static_crate(cmd, sess, tmpdir, crate_type,
943 &src.rlib.unwrap().0, sess.cstore.is_no_builtins(cnum))
945 Linkage::Dynamic => {
946 add_dynamic_crate(cmd, sess, &src.dylib.unwrap().0)
951 // Converts a library file-stem into a cc -l argument
952 fn unlib<'a>(config: &config::Config, stem: &'a str) -> &'a str {
953 if stem.starts_with("lib") && !config.target.options.is_like_windows {
960 // Adds the static "rlib" versions of all crates to the command line.
961 // There's a bit of magic which happens here specifically related to LTO and
962 // dynamic libraries. Specifically:
964 // * For LTO, we remove upstream object files.
965 // * For dylibs we remove metadata and bytecode from upstream rlibs
967 // When performing LTO, almost(*) all of the bytecode from the upstream
968 // libraries has already been included in our object file output. As a
969 // result we need to remove the object files in the upstream libraries so
970 // the linker doesn't try to include them twice (or whine about duplicate
971 // symbols). We must continue to include the rest of the rlib, however, as
972 // it may contain static native libraries which must be linked in.
974 // (*) Crates marked with `#![no_builtins]` don't participate in LTO and
975 // their bytecode wasn't included. The object files in those libraries must
976 // still be passed to the linker.
978 // When making a dynamic library, linkers by default don't include any
979 // object files in an archive if they're not necessary to resolve the link.
980 // We basically want to convert the archive (rlib) to a dylib, though, so we
981 // *do* want everything included in the output, regardless of whether the
982 // linker thinks it's needed or not. As a result we must use the
983 // --whole-archive option (or the platform equivalent). When using this
984 // option the linker will fail if there are non-objects in the archive (such
985 // as our own metadata and/or bytecode). All in all, for rlibs to be
986 // entirely included in dylibs, we need to remove all non-object files.
988 // Note, however, that if we're not doing LTO or we're not producing a dylib
989 // (aka we're making an executable), we can just pass the rlib blindly to
990 // the linker (fast) because it's fine if it's not actually included as
991 // we're at the end of the dependency chain.
992 fn add_static_crate(cmd: &mut Linker,
995 crate_type: config::CrateType,
997 is_a_no_builtins_crate: bool) {
998 if !sess.lto() && crate_type != config::CrateTypeDylib {
999 cmd.link_rlib(&fix_windows_verbatim_for_gcc(cratepath));
1003 let dst = tmpdir.join(cratepath.file_name().unwrap());
1004 let name = cratepath.file_name().unwrap().to_str().unwrap();
1005 let name = &name[3..name.len() - 5]; // chop off lib/.rlib
1007 time(sess.time_passes(), &format!("altering {}.rlib", name), || {
1008 let cfg = archive_config(sess, &dst, Some(cratepath));
1009 let mut archive = ArchiveBuilder::new(cfg);
1010 archive.remove_file(sess.cstore.metadata_filename());
1011 archive.update_symbols();
1013 let mut any_objects = false;
1014 for f in archive.src_files() {
1015 if f.ends_with("bytecode.deflate") {
1016 archive.remove_file(&f);
1019 let canonical = f.replace("-", "_");
1020 let canonical_name = name.replace("-", "_");
1021 if sess.lto() && !is_a_no_builtins_crate &&
1022 canonical.starts_with(&canonical_name) &&
1023 canonical.ends_with(".o") {
1024 let num = &f[name.len()..f.len() - 2];
1025 if num.len() > 0 && num[1..].parse::<u32>().is_ok() {
1026 archive.remove_file(&f);
1035 if crate_type == config::CrateTypeDylib {
1036 cmd.link_whole_rlib(&fix_windows_verbatim_for_gcc(&dst));
1038 cmd.link_rlib(&fix_windows_verbatim_for_gcc(&dst));
1044 // Same thing as above, but for dynamic crates instead of static crates.
1045 fn add_dynamic_crate(cmd: &mut Linker, sess: &Session, cratepath: &Path) {
1046 // If we're performing LTO, then it should have been previously required
1047 // that all upstream rust dependencies were available in an rlib format.
1048 assert!(!sess.lto());
1050 // Just need to tell the linker about where the library lives and
1052 let parent = cratepath.parent();
1053 if let Some(dir) = parent {
1054 cmd.include_path(&fix_windows_verbatim_for_gcc(dir));
1056 let filestem = cratepath.file_stem().unwrap().to_str().unwrap();
1057 cmd.link_rust_dylib(&unlib(&sess.target, filestem),
1058 parent.unwrap_or(Path::new("")));
1062 // Link in all of our upstream crates' native dependencies. Remember that
1063 // all of these upstream native dependencies are all non-static
1064 // dependencies. We've got two cases then:
1066 // 1. The upstream crate is an rlib. In this case we *must* link in the
1067 // native dependency because the rlib is just an archive.
1069 // 2. The upstream crate is a dylib. In order to use the dylib, we have to
1070 // have the dependency present on the system somewhere. Thus, we don't
1071 // gain a whole lot from not linking in the dynamic dependency to this
1074 // The use case for this is a little subtle. In theory the native
1075 // dependencies of a crate are purely an implementation detail of the crate
1076 // itself, but the problem arises with generic and inlined functions. If a
1077 // generic function calls a native function, then the generic function must
1078 // be instantiated in the target crate, meaning that the native symbol must
1079 // also be resolved in the target crate.
1080 fn add_upstream_native_libraries(cmd: &mut Linker, sess: &Session) {
1081 // Be sure to use a topological sorting of crates because there may be
1082 // interdependencies between native libraries. When passing -nodefaultlibs,
1083 // for example, almost all native libraries depend on libc, so we have to
1084 // make sure that's all the way at the right (liblibc is near the base of
1085 // the dependency chain).
1087 // This passes RequireStatic, but the actual requirement doesn't matter,
1088 // we're just getting an ordering of crate numbers, we're not worried about
1090 let crates = sess.cstore.used_crates(LinkagePreference::RequireStatic);
1091 for (cnum, _) in crates {
1092 let libs = sess.cstore.native_libraries(cnum);
1093 for &(kind, ref lib) in &libs {
1095 NativeLibraryKind::NativeUnknown => cmd.link_dylib(lib),
1096 NativeLibraryKind::NativeFramework => cmd.link_framework(lib),
1097 NativeLibraryKind::NativeStatic => {
1098 bug!("statics shouldn't be propagated");