1 use rustc_data_structures::fx::FxHashSet;
2 use rustc_data_structures::temp_dir::MaybeTempDir;
3 use rustc_fs_util::fix_windows_verbatim_for_gcc;
4 use rustc_hir::def_id::CrateNum;
5 use rustc_middle::middle::cstore::{EncodedMetadata, LibSource, NativeLib};
6 use rustc_middle::middle::dependency_format::Linkage;
7 use rustc_session::config::{self, CFGuard, CrateType, DebugInfo};
8 use rustc_session::config::{OutputFilenames, OutputType, PrintRequest, SanitizerSet};
9 use rustc_session::output::{check_file_is_writeable, invalid_output_for_target, out_filename};
10 use rustc_session::search_paths::PathKind;
11 use rustc_session::utils::NativeLibKind;
12 /// For all the linkers we support, and information they might
13 /// need out of the shared crate context before we get rid of it.
14 use rustc_session::{filesearch, Session};
15 use rustc_span::symbol::Symbol;
16 use rustc_target::spec::crt_objects::{CrtObjects, CrtObjectsFallback};
17 use rustc_target::spec::{LinkOutputKind, LinkerFlavor, LldFlavor};
18 use rustc_target::spec::{PanicStrategy, RelocModel, RelroLevel, Target};
20 use super::archive::ArchiveBuilder;
21 use super::command::Command;
22 use super::linker::{self, Linker};
23 use super::rpath::{self, RPathConfig};
25 looks_like_rust_object_file, CodegenResults, CompiledModule, CrateInfo, METADATA_FILENAME,
28 use cc::windows_registry;
29 use tempfile::Builder as TempFileBuilder;
31 use std::ffi::OsString;
32 use std::path::{Path, PathBuf};
33 use std::process::{ExitStatus, Output, Stdio};
34 use std::{ascii, char, env, fmt, fs, io, mem, str};
36 pub fn remove(sess: &Session, path: &Path) {
37 if let Err(e) = fs::remove_file(path) {
38 sess.err(&format!("failed to remove {}: {}", path.display(), e));
42 /// Performs the linkage portion of the compilation phase. This will generate all
43 /// of the requested outputs for this compilation session.
44 pub fn link_binary<'a, B: ArchiveBuilder<'a>>(
46 codegen_results: &CodegenResults,
47 outputs: &OutputFilenames,
51 let _timer = sess.timer("link_binary");
52 let output_metadata = sess.opts.output_types.contains_key(&OutputType::Metadata);
53 for &crate_type in sess.crate_types().iter() {
54 // Ignore executable crates if we have -Z no-codegen, as they will error.
55 if (sess.opts.debugging_opts.no_codegen || !sess.opts.output_types.should_codegen())
57 && crate_type == CrateType::Executable
62 if invalid_output_for_target(sess, crate_type) {
64 "invalid output type `{:?}` for target os `{}`",
66 sess.opts.target_triple
70 sess.time("link_binary_check_files_are_writeable", || {
71 for obj in codegen_results.modules.iter().filter_map(|m| m.object.as_ref()) {
72 check_file_is_writeable(obj, sess);
76 if outputs.outputs.should_codegen() {
77 let tmpdir = TempFileBuilder::new()
80 .unwrap_or_else(|err| sess.fatal(&format!("couldn't create a temp dir: {}", err)));
81 let path = MaybeTempDir::new(tmpdir, sess.opts.cg.save_temps);
82 let out_filename = out_filename(sess, crate_type, outputs, crate_name);
85 let _timer = sess.timer("link_rlib");
86 link_rlib::<B>(sess, codegen_results, RlibFlavor::Normal, &out_filename, &path)
89 CrateType::Staticlib => {
90 link_staticlib::<B>(sess, codegen_results, &out_filename, &path);
101 if sess.opts.debugging_opts.split_dwarf == config::SplitDwarfKind::Split {
102 link_dwarf_object(sess, &out_filename);
106 if sess.opts.json_artifact_notifications {
107 sess.parse_sess.span_diagnostic.emit_artifact_notification(&out_filename, "link");
112 // Remove the temporary object file and metadata if we aren't saving temps
113 sess.time("link_binary_remove_temps", || {
114 if !sess.opts.cg.save_temps {
115 let remove_temps_from_module = |module: &CompiledModule| {
116 if let Some(ref obj) = module.object {
120 if let Some(ref obj) = module.dwarf_object {
125 if sess.opts.output_types.should_codegen()
126 && !preserve_objects_for_their_debuginfo(sess)
128 for module in &codegen_results.modules {
129 remove_temps_from_module(module);
133 if let Some(ref metadata_module) = codegen_results.metadata_module {
134 remove_temps_from_module(metadata_module);
137 if let Some(ref allocator_module) = codegen_results.allocator_module {
138 remove_temps_from_module(allocator_module);
144 // The third parameter is for env vars, used on windows to set up the
145 // path for MSVC to find its DLLs, and gcc to find its bundled
150 flavor: LinkerFlavor,
151 self_contained: bool,
153 let msvc_tool = windows_registry::find_tool(&sess.opts.target_triple.triple(), "link.exe");
155 // If our linker looks like a batch script on Windows then to execute this
156 // we'll need to spawn `cmd` explicitly. This is primarily done to handle
157 // emscripten where the linker is `emcc.bat` and needs to be spawned as
158 // `cmd /c emcc.bat ...`.
160 // This worked historically but is needed manually since #42436 (regression
161 // was tagged as #42791) and some more info can be found on #44443 for
162 // emscripten itself.
163 let mut cmd = match linker.to_str() {
164 Some(linker) if cfg!(windows) && linker.ends_with(".bat") => Command::bat_script(linker),
166 LinkerFlavor::Lld(f) => Command::lld(linker, f),
167 LinkerFlavor::Msvc if sess.opts.cg.linker.is_none() && sess.target.linker.is_none() => {
168 Command::new(msvc_tool.as_ref().map(|t| t.path()).unwrap_or(linker))
170 _ => Command::new(linker),
174 // UWP apps have API restrictions enforced during Store submissions.
175 // To comply with the Windows App Certification Kit,
176 // MSVC needs to link with the Store versions of the runtime libraries (vcruntime, msvcrt, etc).
177 let t = &sess.target;
178 if (flavor == LinkerFlavor::Msvc || flavor == LinkerFlavor::Lld(LldFlavor::Link))
181 if let Some(ref tool) = msvc_tool {
182 let original_path = tool.path();
183 if let Some(ref root_lib_path) = original_path.ancestors().nth(4) {
184 let arch = match t.arch.as_str() {
185 "x86_64" => Some("x64".to_string()),
186 "x86" => Some("x86".to_string()),
187 "aarch64" => Some("arm64".to_string()),
188 "arm" => Some("arm".to_string()),
191 if let Some(ref a) = arch {
192 // FIXME: Move this to `fn linker_with_args`.
193 let mut arg = OsString::from("/LIBPATH:");
194 arg.push(format!("{}\\lib\\{}\\store", root_lib_path.display(), a.to_string()));
197 warn!("arch is not supported");
200 warn!("MSVC root path lib location not found");
203 warn!("link.exe not found");
207 // The compiler's sysroot often has some bundled tools, so add it to the
208 // PATH for the child.
209 let mut new_path = sess.host_filesearch(PathKind::All).get_tools_search_paths(self_contained);
210 let mut msvc_changed_path = false;
211 if sess.target.is_like_msvc {
212 if let Some(ref tool) = msvc_tool {
213 cmd.args(tool.args());
214 for &(ref k, ref v) in tool.env() {
216 new_path.extend(env::split_paths(v));
217 msvc_changed_path = true;
225 if !msvc_changed_path {
226 if let Some(path) = env::var_os("PATH") {
227 new_path.extend(env::split_paths(&path));
230 cmd.env("PATH", env::join_paths(new_path).unwrap());
235 pub fn each_linked_rlib(
237 f: &mut dyn FnMut(CrateNum, &Path),
238 ) -> Result<(), String> {
239 let crates = info.used_crates_static.iter();
241 for (ty, list) in info.dependency_formats.iter() {
243 CrateType::Executable
244 | CrateType::Staticlib
246 | CrateType::ProcMacro => {
253 let fmts = match fmts {
255 None => return Err("could not find formats for rlibs".to_string()),
257 for &(cnum, ref path) in crates {
258 match fmts.get(cnum.as_usize() - 1) {
259 Some(&Linkage::NotLinked | &Linkage::IncludedFromDylib) => continue,
261 None => return Err("could not find formats for rlibs".to_string()),
263 let name = &info.crate_name[&cnum];
264 let path = match *path {
265 LibSource::Some(ref p) => p,
266 LibSource::MetadataOnly => {
268 "could not find rlib for: `{}`, found rmeta (metadata) file",
272 LibSource::None => return Err(format!("could not find rlib for: `{}`", name)),
279 /// We use a temp directory here to avoid races between concurrent rustc processes,
280 /// such as builds in the same directory using the same filename for metadata while
281 /// building an `.rlib` (stomping over one another), or writing an `.rmeta` into a
282 /// directory being searched for `extern crate` (observing an incomplete file).
283 /// The returned path is the temporary file containing the complete metadata.
284 pub fn emit_metadata(sess: &Session, metadata: &EncodedMetadata, tmpdir: &MaybeTempDir) -> PathBuf {
285 let out_filename = tmpdir.as_ref().join(METADATA_FILENAME);
286 let result = fs::write(&out_filename, &metadata.raw_data);
288 if let Err(e) = result {
289 sess.fatal(&format!("failed to write {}: {}", out_filename.display(), e));
295 /// Create an 'rlib'.
297 /// An rlib in its current incarnation is essentially a renamed .a file. The rlib primarily contains
298 /// the object file of the crate, but it also contains all of the object files from native
299 /// libraries. This is done by unzipping native libraries and inserting all of the contents into
301 fn link_rlib<'a, B: ArchiveBuilder<'a>>(
303 codegen_results: &CodegenResults,
306 tmpdir: &MaybeTempDir,
308 info!("preparing rlib to {:?}", out_filename);
309 let mut ab = <B as ArchiveBuilder>::new(sess, out_filename, None);
311 for obj in codegen_results.modules.iter().filter_map(|m| m.object.as_ref()) {
315 // Note that in this loop we are ignoring the value of `lib.cfg`. That is,
316 // we may not be configured to actually include a static library if we're
317 // adding it here. That's because later when we consume this rlib we'll
318 // decide whether we actually needed the static library or not.
320 // To do this "correctly" we'd need to keep track of which libraries added
321 // which object files to the archive. We don't do that here, however. The
322 // #[link(cfg(..))] feature is unstable, though, and only intended to get
323 // liblibc working. In that sense the check below just indicates that if
324 // there are any libraries we want to omit object files for at link time we
325 // just exclude all custom object files.
327 // Eventually if we want to stabilize or flesh out the #[link(cfg(..))]
328 // feature then we'll need to figure out how to record what objects were
329 // loaded from the libraries found here and then encode that into the
330 // metadata of the rlib we're generating somehow.
331 for lib in codegen_results.crate_info.used_libraries.iter() {
333 NativeLibKind::StaticBundle => {}
334 NativeLibKind::StaticNoBundle
335 | NativeLibKind::Dylib
336 | NativeLibKind::Framework
337 | NativeLibKind::RawDylib
338 | NativeLibKind::Unspecified => continue,
340 if let Some(name) = lib.name {
341 ab.add_native_library(name);
345 // After adding all files to the archive, we need to update the
346 // symbol table of the archive.
349 // Note that it is important that we add all of our non-object "magical
350 // files" *after* all of the object files in the archive. The reason for
351 // this is as follows:
353 // * When performing LTO, this archive will be modified to remove
354 // objects from above. The reason for this is described below.
356 // * When the system linker looks at an archive, it will attempt to
357 // determine the architecture of the archive in order to see whether its
360 // The algorithm for this detection is: iterate over the files in the
361 // archive. Skip magical SYMDEF names. Interpret the first file as an
362 // object file. Read architecture from the object file.
364 // * As one can probably see, if "metadata" and "foo.bc" were placed
365 // before all of the objects, then the architecture of this archive would
366 // not be correctly inferred once 'foo.o' is removed.
368 // Basically, all this means is that this code should not move above the
371 RlibFlavor::Normal => {
372 // Instead of putting the metadata in an object file section, rlibs
373 // contain the metadata in a separate file.
374 ab.add_file(&emit_metadata(sess, &codegen_results.metadata, tmpdir));
376 // After adding all files to the archive, we need to update the
377 // symbol table of the archive. This currently dies on macOS (see
378 // #11162), and isn't necessary there anyway
379 if !sess.target.is_like_osx {
384 RlibFlavor::StaticlibBase => {
385 let obj = codegen_results.allocator_module.as_ref().and_then(|m| m.object.as_ref());
386 if let Some(obj) = obj {
395 /// Create a static archive.
397 /// This is essentially the same thing as an rlib, but it also involves adding all of the upstream
398 /// crates' objects into the archive. This will slurp in all of the native libraries of upstream
399 /// dependencies as well.
401 /// Additionally, there's no way for us to link dynamic libraries, so we warn about all dynamic
402 /// library dependencies that they're not linked in.
404 /// There's no need to include metadata in a static archive, so ensure to not link in the metadata
405 /// object file (and also don't prepare the archive with a metadata file).
406 fn link_staticlib<'a, B: ArchiveBuilder<'a>>(
408 codegen_results: &CodegenResults,
410 tempdir: &MaybeTempDir,
413 link_rlib::<B>(sess, codegen_results, RlibFlavor::StaticlibBase, out_filename, tempdir);
414 let mut all_native_libs = vec![];
416 let res = each_linked_rlib(&codegen_results.crate_info, &mut |cnum, path| {
417 let name = &codegen_results.crate_info.crate_name[&cnum];
418 let native_libs = &codegen_results.crate_info.native_libraries[&cnum];
420 // Here when we include the rlib into our staticlib we need to make a
421 // decision whether to include the extra object files along the way.
422 // These extra object files come from statically included native
423 // libraries, but they may be cfg'd away with #[link(cfg(..))].
425 // This unstable feature, though, only needs liblibc to work. The only
426 // use case there is where musl is statically included in liblibc.rlib,
427 // so if we don't want the included version we just need to skip it. As
428 // a result the logic here is that if *any* linked library is cfg'd away
429 // we just skip all object files.
431 // Clearly this is not sufficient for a general purpose feature, and
432 // we'd want to read from the library's metadata to determine which
433 // object files come from where and selectively skip them.
434 let skip_object_files = native_libs
436 .any(|lib| lib.kind == NativeLibKind::StaticBundle && !relevant_lib(sess, lib));
440 are_upstream_rust_objects_already_included(sess)
441 && !ignored_for_lto(sess, &codegen_results.crate_info, cnum),
446 all_native_libs.extend(codegen_results.crate_info.native_libraries[&cnum].iter().cloned());
448 if let Err(e) = res {
455 if !all_native_libs.is_empty() {
456 if sess.opts.prints.contains(&PrintRequest::NativeStaticLibs) {
457 print_native_static_libs(sess, &all_native_libs);
462 fn escape_stdout_stderr_string(s: &[u8]) -> String {
463 str::from_utf8(s).map(|s| s.to_owned()).unwrap_or_else(|_| {
464 let mut x = "Non-UTF-8 output: ".to_string();
465 x.extend(s.iter().flat_map(|&b| ascii::escape_default(b)).map(char::from));
470 const LLVM_DWP_EXECUTABLE: &'static str = "rust-llvm-dwp";
472 /// Invoke `llvm-dwp` (shipped alongside rustc) to link `dwo` files from Split DWARF into a `dwp`
474 fn link_dwarf_object<'a>(sess: &'a Session, executable_out_filename: &Path) {
475 info!("preparing dwp to {}.dwp", executable_out_filename.to_str().unwrap());
477 let dwp_out_filename = executable_out_filename.with_extension("dwp");
478 let mut cmd = Command::new(LLVM_DWP_EXECUTABLE);
480 cmd.arg(executable_out_filename);
482 cmd.arg(&dwp_out_filename);
484 let mut new_path = sess.host_filesearch(PathKind::All).get_tools_search_paths(false);
485 if let Some(path) = env::var_os("PATH") {
486 new_path.extend(env::split_paths(&path));
488 let new_path = env::join_paths(new_path).unwrap();
489 cmd.env("PATH", new_path);
492 match sess.time("run_dwp", || cmd.output()) {
493 Ok(prog) if !prog.status.success() => {
494 sess.struct_err(&format!(
495 "linking dwarf objects with `{}` failed: {}",
496 LLVM_DWP_EXECUTABLE, prog.status
498 .note(&format!("{:?}", &cmd))
499 .note(&escape_stdout_stderr_string(&prog.stdout))
500 .note(&escape_stdout_stderr_string(&prog.stderr))
502 info!("linker stderr:\n{}", escape_stdout_stderr_string(&prog.stderr));
503 info!("linker stdout:\n{}", escape_stdout_stderr_string(&prog.stdout));
507 let dwp_not_found = e.kind() == io::ErrorKind::NotFound;
508 let mut err = if dwp_not_found {
509 sess.struct_err(&format!("linker `{}` not found", LLVM_DWP_EXECUTABLE))
511 sess.struct_err(&format!("could not exec the linker `{}`", LLVM_DWP_EXECUTABLE))
514 err.note(&e.to_string());
517 err.note(&format!("{:?}", &cmd));
525 /// Create a dynamic library or executable.
527 /// This will invoke the system linker/cc to create the resulting file. This links to all upstream
529 fn link_natively<'a, B: ArchiveBuilder<'a>>(
531 crate_type: CrateType,
533 codegen_results: &CodegenResults,
537 info!("preparing {:?} to {:?}", crate_type, out_filename);
538 let (linker_path, flavor) = linker_and_flavor(sess);
539 let mut cmd = linker_with_args::<B>(
550 linker::disable_localization(&mut cmd);
552 for &(ref k, ref v) in &sess.target.link_env {
555 for k in &sess.target.link_env_remove {
559 if sess.opts.debugging_opts.print_link_args {
560 println!("{:?}", &cmd);
563 // May have not found libraries in the right formats.
564 sess.abort_if_errors();
566 // Invoke the system linker
568 let retry_on_segfault = env::var("RUSTC_RETRY_LINKER_ON_SEGFAULT").is_ok();
573 prog = sess.time("run_linker", || exec_linker(sess, &cmd, out_filename, tmpdir));
574 let output = match prog {
575 Ok(ref output) => output,
578 if output.status.success() {
581 let mut out = output.stderr.clone();
582 out.extend(&output.stdout);
583 let out = String::from_utf8_lossy(&out);
585 // Check to see if the link failed with "unrecognized command line option:
586 // '-no-pie'" for gcc or "unknown argument: '-no-pie'" for clang. If so,
587 // reperform the link step without the -no-pie option. This is safe because
588 // if the linker doesn't support -no-pie then it should not default to
589 // linking executables as pie. Different versions of gcc seem to use
590 // different quotes in the error message so don't check for them.
591 if sess.target.linker_is_gnu
592 && flavor != LinkerFlavor::Ld
593 && (out.contains("unrecognized command line option")
594 || out.contains("unknown argument"))
595 && out.contains("-no-pie")
596 && cmd.get_args().iter().any(|e| e.to_string_lossy() == "-no-pie")
598 info!("linker output: {:?}", out);
599 warn!("Linker does not support -no-pie command line option. Retrying without.");
600 for arg in cmd.take_args() {
601 if arg.to_string_lossy() != "-no-pie" {
609 // Detect '-static-pie' used with an older version of gcc or clang not supporting it.
610 // Fallback from '-static-pie' to '-static' in that case.
611 if sess.target.linker_is_gnu
612 && flavor != LinkerFlavor::Ld
613 && (out.contains("unrecognized command line option")
614 || out.contains("unknown argument"))
615 && (out.contains("-static-pie") || out.contains("--no-dynamic-linker"))
616 && cmd.get_args().iter().any(|e| e.to_string_lossy() == "-static-pie")
618 info!("linker output: {:?}", out);
620 "Linker does not support -static-pie command line option. Retrying with -static instead."
622 // Mirror `add_(pre,post)_link_objects` to replace CRT objects.
623 let self_contained = crt_objects_fallback(sess, crate_type);
624 let opts = &sess.target;
625 let pre_objects = if self_contained {
626 &opts.pre_link_objects_fallback
628 &opts.pre_link_objects
630 let post_objects = if self_contained {
631 &opts.post_link_objects_fallback
633 &opts.post_link_objects
635 let get_objects = |objects: &CrtObjects, kind| {
641 .map(|obj| get_object_file_path(sess, obj, self_contained).into_os_string())
644 let pre_objects_static_pie = get_objects(pre_objects, LinkOutputKind::StaticPicExe);
645 let post_objects_static_pie = get_objects(post_objects, LinkOutputKind::StaticPicExe);
646 let mut pre_objects_static = get_objects(pre_objects, LinkOutputKind::StaticNoPicExe);
647 let mut post_objects_static = get_objects(post_objects, LinkOutputKind::StaticNoPicExe);
648 // Assume that we know insertion positions for the replacement arguments from replaced
649 // arguments, which is true for all supported targets.
650 assert!(pre_objects_static.is_empty() || !pre_objects_static_pie.is_empty());
651 assert!(post_objects_static.is_empty() || !post_objects_static_pie.is_empty());
652 for arg in cmd.take_args() {
653 if arg.to_string_lossy() == "-static-pie" {
654 // Replace the output kind.
656 } else if pre_objects_static_pie.contains(&arg) {
657 // Replace the pre-link objects (replace the first and remove the rest).
658 cmd.args(mem::take(&mut pre_objects_static));
659 } else if post_objects_static_pie.contains(&arg) {
660 // Replace the post-link objects (replace the first and remove the rest).
661 cmd.args(mem::take(&mut post_objects_static));
670 // Here's a terribly awful hack that really shouldn't be present in any
671 // compiler. Here an environment variable is supported to automatically
672 // retry the linker invocation if the linker looks like it segfaulted.
674 // Gee that seems odd, normally segfaults are things we want to know
675 // about! Unfortunately though in rust-lang/rust#38878 we're
676 // experiencing the linker segfaulting on Travis quite a bit which is
677 // causing quite a bit of pain to land PRs when they spuriously fail
678 // due to a segfault.
680 // The issue #38878 has some more debugging information on it as well,
681 // but this unfortunately looks like it's just a race condition in
682 // macOS's linker with some thread pool working in the background. It
683 // seems that no one currently knows a fix for this so in the meantime
684 // we're left with this...
685 if !retry_on_segfault || i > 3 {
688 let msg_segv = "clang: error: unable to execute command: Segmentation fault: 11";
689 let msg_bus = "clang: error: unable to execute command: Bus error: 10";
690 if out.contains(msg_segv) || out.contains(msg_bus) {
692 "looks like the linker segfaulted when we tried to call it, \
693 automatically retrying again. cmd = {:?}, out = {}.",
699 if is_illegal_instruction(&output.status) {
701 "looks like the linker hit an illegal instruction when we \
702 tried to call it, automatically retrying again. cmd = {:?}, ]\
703 out = {}, status = {}.",
704 cmd, out, output.status,
710 fn is_illegal_instruction(status: &ExitStatus) -> bool {
711 use std::os::unix::prelude::*;
712 status.signal() == Some(libc::SIGILL)
716 fn is_illegal_instruction(_status: &ExitStatus) -> bool {
721 fn escape_string(s: &[u8]) -> String {
722 str::from_utf8(s).map(|s| s.to_owned()).unwrap_or_else(|_| {
723 let mut x = "Non-UTF-8 output: ".to_string();
724 x.extend(s.iter().flat_map(|&b| ascii::escape_default(b)).map(char::from));
731 if !prog.status.success() {
732 let mut output = prog.stderr.clone();
733 output.extend_from_slice(&prog.stdout);
734 sess.struct_err(&format!(
735 "linking with `{}` failed: {}",
736 linker_path.display(),
739 .note(&format!("{:?}", &cmd))
740 .note(&escape_stdout_stderr_string(&output))
743 // If MSVC's `link.exe` was expected but the return code
744 // is not a Microsoft LNK error then suggest a way to fix or
745 // install the Visual Studio build tools.
746 if let Some(code) = prog.status.code() {
747 if sess.target.is_like_msvc
748 && flavor == LinkerFlavor::Msvc
749 // Respect the command line override
750 && sess.opts.cg.linker.is_none()
751 // Match exactly "link.exe"
752 && linker_path.to_str() == Some("link.exe")
753 // All Microsoft `link.exe` linking error codes are
754 // four digit numbers in the range 1000 to 9999 inclusive
755 && (code < 1000 || code > 9999)
757 let is_vs_installed = windows_registry::find_vs_version().is_ok();
758 let has_linker = windows_registry::find_tool(
759 &sess.opts.target_triple.triple(),
764 sess.note_without_error("`link.exe` returned an unexpected error");
765 if is_vs_installed && has_linker {
766 // the linker is broken
767 sess.note_without_error(
768 "the Visual Studio build tools may need to be repaired \
769 using the Visual Studio installer",
771 sess.note_without_error(
772 "or a necessary component may be missing from the \
773 \"C++ build tools\" workload",
775 } else if is_vs_installed {
776 // the linker is not installed
777 sess.note_without_error(
778 "in the Visual Studio installer, ensure the \
779 \"C++ build tools\" workload is selected",
782 // visual studio is not installed
783 sess.note_without_error(
784 "you may need to install Visual Studio build tools with the \
785 \"C++ build tools\" workload",
791 sess.abort_if_errors();
793 info!("linker stderr:\n{}", escape_stdout_stderr_string(&prog.stderr));
794 info!("linker stdout:\n{}", escape_stdout_stderr_string(&prog.stdout));
797 let linker_not_found = e.kind() == io::ErrorKind::NotFound;
799 let mut linker_error = {
800 if linker_not_found {
801 sess.struct_err(&format!("linker `{}` not found", linker_path.display()))
803 sess.struct_err(&format!(
804 "could not exec the linker `{}`",
805 linker_path.display()
810 linker_error.note(&e.to_string());
812 if !linker_not_found {
813 linker_error.note(&format!("{:?}", &cmd));
818 if sess.target.is_like_msvc && linker_not_found {
819 sess.note_without_error(
820 "the msvc targets depend on the msvc linker \
821 but `link.exe` was not found",
823 sess.note_without_error(
824 "please ensure that VS 2013, VS 2015, VS 2017 or VS 2019 \
825 was installed with the Visual C++ option",
828 sess.abort_if_errors();
832 // On macOS, debuggers need this utility to get run to do some munging of
833 // the symbols. Note, though, that if the object files are being preserved
834 // for their debug information there's no need for us to run dsymutil.
835 if sess.target.is_like_osx
836 && sess.opts.debuginfo != DebugInfo::None
837 && !preserve_objects_for_their_debuginfo(sess)
839 let prog = Command::new("dsymutil").arg(out_filename).output();
842 if !prog.status.success() {
843 let mut output = prog.stderr.clone();
844 output.extend_from_slice(&prog.stdout);
845 sess.struct_warn(&format!(
846 "processing debug info with `dsymutil` failed: {}",
849 .note(&escape_string(&output))
853 Err(e) => sess.fatal(&format!("unable to run `dsymutil`: {}", e)),
858 fn link_sanitizers(sess: &Session, crate_type: CrateType, linker: &mut dyn Linker) {
859 // On macOS the runtimes are distributed as dylibs which should be linked to
860 // both executables and dynamic shared objects. Everywhere else the runtimes
861 // are currently distributed as static liraries which should be linked to
863 let needs_runtime = match crate_type {
864 CrateType::Executable => true,
865 CrateType::Dylib | CrateType::Cdylib | CrateType::ProcMacro => sess.target.is_like_osx,
866 CrateType::Rlib | CrateType::Staticlib => false,
873 let sanitizer = sess.opts.debugging_opts.sanitizer;
874 if sanitizer.contains(SanitizerSet::ADDRESS) {
875 link_sanitizer_runtime(sess, linker, "asan");
877 if sanitizer.contains(SanitizerSet::LEAK) {
878 link_sanitizer_runtime(sess, linker, "lsan");
880 if sanitizer.contains(SanitizerSet::MEMORY) {
881 link_sanitizer_runtime(sess, linker, "msan");
883 if sanitizer.contains(SanitizerSet::THREAD) {
884 link_sanitizer_runtime(sess, linker, "tsan");
888 fn link_sanitizer_runtime(sess: &Session, linker: &mut dyn Linker, name: &str) {
889 let default_sysroot = filesearch::get_or_default_sysroot();
891 filesearch::make_target_lib_path(&default_sysroot, sess.opts.target_triple.triple());
892 let channel = option_env!("CFG_RELEASE_CHANNEL")
893 .map(|channel| format!("-{}", channel))
894 .unwrap_or_default();
896 match sess.opts.target_triple.triple() {
897 "x86_64-apple-darwin" => {
898 // On Apple platforms, the sanitizer is always built as a dylib, and
899 // LLVM will link to `@rpath/*.dylib`, so we need to specify an
900 // rpath to the library as well (the rpath should be absolute, see
901 // PR #41352 for details).
902 let libname = format!("rustc{}_rt.{}", channel, name);
903 let rpath = default_tlib.to_str().expect("non-utf8 component in path");
904 linker.args(&["-Wl,-rpath", "-Xlinker", rpath]);
905 linker.link_dylib(Symbol::intern(&libname));
908 | "aarch64-unknown-linux-gnu"
910 | "x86_64-unknown-freebsd"
911 | "x86_64-unknown-linux-gnu" => {
912 let filename = format!("librustc{}_rt.{}.a", channel, name);
913 let path = default_tlib.join(&filename);
914 linker.link_whole_rlib(&path);
920 /// Returns a boolean indicating whether the specified crate should be ignored
923 /// Crates ignored during LTO are not lumped together in the "massive object
924 /// file" that we create and are linked in their normal rlib states. See
925 /// comments below for what crates do not participate in LTO.
927 /// It's unusual for a crate to not participate in LTO. Typically only
928 /// compiler-specific and unstable crates have a reason to not participate in
930 pub fn ignored_for_lto(sess: &Session, info: &CrateInfo, cnum: CrateNum) -> bool {
931 // If our target enables builtin function lowering in LLVM then the
932 // crates providing these functions don't participate in LTO (e.g.
933 // no_builtins or compiler builtins crates).
934 !sess.target.no_builtins
935 && (info.compiler_builtins == Some(cnum) || info.is_no_builtins.contains(&cnum))
938 fn linker_and_flavor(sess: &Session) -> (PathBuf, LinkerFlavor) {
941 linker: Option<PathBuf>,
942 flavor: Option<LinkerFlavor>,
943 ) -> Option<(PathBuf, LinkerFlavor)> {
944 match (linker, flavor) {
945 (Some(linker), Some(flavor)) => Some((linker, flavor)),
946 // only the linker flavor is known; use the default linker for the selected flavor
947 (None, Some(flavor)) => Some((
948 PathBuf::from(match flavor {
949 LinkerFlavor::Em => {
956 LinkerFlavor::Gcc => {
957 if cfg!(any(target_os = "solaris", target_os = "illumos")) {
958 // On historical Solaris systems, "cc" may have
959 // been Sun Studio, which is not flag-compatible
960 // with "gcc". This history casts a long shadow,
961 // and many modern illumos distributions today
962 // ship GCC as "gcc" without also making it
963 // available as "cc".
969 LinkerFlavor::Ld => "ld",
970 LinkerFlavor::Msvc => "link.exe",
971 LinkerFlavor::Lld(_) => "lld",
972 LinkerFlavor::PtxLinker => "rust-ptx-linker",
976 (Some(linker), None) => {
977 let stem = linker.file_stem().and_then(|stem| stem.to_str()).unwrap_or_else(|| {
978 sess.fatal("couldn't extract file stem from specified linker")
981 let flavor = if stem == "emcc" {
983 } else if stem == "gcc"
984 || stem.ends_with("-gcc")
986 || stem.ends_with("-clang")
989 } else if stem == "ld" || stem == "ld.lld" || stem.ends_with("-ld") {
991 } else if stem == "link" || stem == "lld-link" {
993 } else if stem == "lld" || stem == "rust-lld" {
994 LinkerFlavor::Lld(sess.target.lld_flavor)
996 // fall back to the value in the target spec
997 sess.target.linker_flavor
1000 Some((linker, flavor))
1002 (None, None) => None,
1006 // linker and linker flavor specified via command line have precedence over what the target
1007 // specification specifies
1008 if let Some(ret) = infer_from(sess, sess.opts.cg.linker.clone(), sess.opts.cg.linker_flavor) {
1012 if let Some(ret) = infer_from(
1014 sess.target.linker.clone().map(PathBuf::from),
1015 Some(sess.target.linker_flavor),
1020 bug!("Not enough information provided to determine how to invoke the linker");
1023 /// Returns a boolean indicating whether we should preserve the object files on
1024 /// the filesystem for their debug information. This is often useful with
1025 /// split-dwarf like schemes.
1026 fn preserve_objects_for_their_debuginfo(sess: &Session) -> bool {
1027 // If the objects don't have debuginfo there's nothing to preserve.
1028 if sess.opts.debuginfo == config::DebugInfo::None {
1032 // If we're only producing artifacts that are archives, no need to preserve
1033 // the objects as they're losslessly contained inside the archives.
1035 sess.crate_types().iter().any(|&x| x != CrateType::Rlib && x != CrateType::Staticlib);
1040 // Single mode keeps debuginfo in the same object file, but in such a way that it it skipped
1041 // by the linker - so it's expected that when codegen units are linked together that this
1042 // debuginfo would be lost without keeping around the temps.
1043 if sess.opts.debugging_opts.split_dwarf == config::SplitDwarfKind::Single {
1047 // If we're on OSX then the equivalent of split dwarf is turned on by
1048 // default. The final executable won't actually have any debug information
1049 // except it'll have pointers to elsewhere. Historically we've always run
1050 // `dsymutil` to "link all the dwarf together" but this is actually sort of
1051 // a bummer for incremental compilation! (the whole point of split dwarf is
1052 // that you don't do this sort of dwarf link).
1054 // Basically as a result this just means that if we're on OSX and we're
1055 // *not* running dsymutil then the object files are the only source of truth
1056 // for debug information, so we must preserve them.
1057 if sess.target.is_like_osx {
1058 return !sess.opts.debugging_opts.run_dsymutil;
1064 pub fn archive_search_paths(sess: &Session) -> Vec<PathBuf> {
1065 sess.target_filesearch(PathKind::Native).search_path_dirs()
1073 fn print_native_static_libs(sess: &Session, all_native_libs: &[NativeLib]) {
1074 let lib_args: Vec<_> = all_native_libs
1076 .filter(|l| relevant_lib(sess, l))
1078 let name = lib.name?;
1080 NativeLibKind::StaticNoBundle
1081 | NativeLibKind::Dylib
1082 | NativeLibKind::Unspecified => {
1083 if sess.target.is_like_msvc {
1084 Some(format!("{}.lib", name))
1086 Some(format!("-l{}", name))
1089 NativeLibKind::Framework => {
1090 // ld-only syntax, since there are no frameworks in MSVC
1091 Some(format!("-framework {}", name))
1093 // These are included, no need to print them
1094 NativeLibKind::StaticBundle | NativeLibKind::RawDylib => None,
1098 if !lib_args.is_empty() {
1099 sess.note_without_error(
1100 "Link against the following native artifacts when linking \
1101 against this static library. The order and any duplication \
1102 can be significant on some platforms.",
1104 // Prefix for greppability
1105 sess.note_without_error(&format!("native-static-libs: {}", &lib_args.join(" ")));
1109 fn get_object_file_path(sess: &Session, name: &str, self_contained: bool) -> PathBuf {
1110 let fs = sess.target_filesearch(PathKind::Native);
1111 let file_path = fs.get_lib_path().join(name);
1112 if file_path.exists() {
1115 // Special directory with objects used only in self-contained linkage mode
1117 let file_path = fs.get_self_contained_lib_path().join(name);
1118 if file_path.exists() {
1122 for search_path in fs.search_paths() {
1123 let file_path = search_path.dir.join(name);
1124 if file_path.exists() {
1134 out_filename: &Path,
1136 ) -> io::Result<Output> {
1137 // When attempting to spawn the linker we run a risk of blowing out the
1138 // size limits for spawning a new process with respect to the arguments
1139 // we pass on the command line.
1141 // Here we attempt to handle errors from the OS saying "your list of
1142 // arguments is too big" by reinvoking the linker again with an `@`-file
1143 // that contains all the arguments. The theory is that this is then
1144 // accepted on all linkers and the linker will read all its options out of
1145 // there instead of looking at the command line.
1146 if !cmd.very_likely_to_exceed_some_spawn_limit() {
1147 match cmd.command().stdout(Stdio::piped()).stderr(Stdio::piped()).spawn() {
1149 let output = child.wait_with_output();
1150 flush_linked_file(&output, out_filename)?;
1153 Err(ref e) if command_line_too_big(e) => {
1154 info!("command line to linker was too big: {}", e);
1156 Err(e) => return Err(e),
1160 info!("falling back to passing arguments to linker via an @-file");
1161 let mut cmd2 = cmd.clone();
1162 let mut args = String::new();
1163 for arg in cmd2.take_args() {
1165 &Escape { arg: arg.to_str().unwrap(), is_like_msvc: sess.target.is_like_msvc }
1170 let file = tmpdir.join("linker-arguments");
1171 let bytes = if sess.target.is_like_msvc {
1172 let mut out = Vec::with_capacity((1 + args.len()) * 2);
1173 // start the stream with a UTF-16 BOM
1174 for c in std::iter::once(0xFEFF).chain(args.encode_utf16()) {
1175 // encode in little endian
1177 out.push((c >> 8) as u8);
1183 fs::write(&file, &bytes)?;
1184 cmd2.arg(format!("@{}", file.display()));
1185 info!("invoking linker {:?}", cmd2);
1186 let output = cmd2.output();
1187 flush_linked_file(&output, out_filename)?;
1191 fn flush_linked_file(_: &io::Result<Output>, _: &Path) -> io::Result<()> {
1196 fn flush_linked_file(
1197 command_output: &io::Result<Output>,
1198 out_filename: &Path,
1199 ) -> io::Result<()> {
1200 // On Windows, under high I/O load, output buffers are sometimes not flushed,
1201 // even long after process exit, causing nasty, non-reproducible output bugs.
1203 // File::sync_all() calls FlushFileBuffers() down the line, which solves the problem.
1205 // А full writeup of the original Chrome bug can be found at
1206 // randomascii.wordpress.com/2018/02/25/compiler-bug-linker-bug-windows-kernel-bug/amp
1208 if let &Ok(ref out) = command_output {
1209 if out.status.success() {
1210 if let Ok(of) = fs::OpenOptions::new().write(true).open(out_filename) {
1220 fn command_line_too_big(err: &io::Error) -> bool {
1221 err.raw_os_error() == Some(::libc::E2BIG)
1225 fn command_line_too_big(err: &io::Error) -> bool {
1226 const ERROR_FILENAME_EXCED_RANGE: i32 = 206;
1227 err.raw_os_error() == Some(ERROR_FILENAME_EXCED_RANGE)
1235 impl<'a> fmt::Display for Escape<'a> {
1236 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1237 if self.is_like_msvc {
1238 // This is "documented" at
1239 // https://docs.microsoft.com/en-us/cpp/build/reference/at-specify-a-linker-response-file
1241 // Unfortunately there's not a great specification of the
1242 // syntax I could find online (at least) but some local
1243 // testing showed that this seemed sufficient-ish to catch
1244 // at least a few edge cases.
1246 for c in self.arg.chars() {
1248 '"' => write!(f, "\\{}", c)?,
1249 c => write!(f, "{}", c)?,
1254 // This is documented at https://linux.die.net/man/1/ld, namely:
1256 // > Options in file are separated by whitespace. A whitespace
1257 // > character may be included in an option by surrounding the
1258 // > entire option in either single or double quotes. Any
1259 // > character (including a backslash) may be included by
1260 // > prefixing the character to be included with a backslash.
1262 // We put an argument on each line, so all we need to do is
1263 // ensure the line is interpreted as one whole argument.
1264 for c in self.arg.chars() {
1266 '\\' | ' ' => write!(f, "\\{}", c)?,
1267 c => write!(f, "{}", c)?,
1276 fn link_output_kind(sess: &Session, crate_type: CrateType) -> LinkOutputKind {
1277 let kind = match (crate_type, sess.crt_static(Some(crate_type)), sess.relocation_model()) {
1278 (CrateType::Executable, false, RelocModel::Pic) => LinkOutputKind::DynamicPicExe,
1279 (CrateType::Executable, false, _) => LinkOutputKind::DynamicNoPicExe,
1280 (CrateType::Executable, true, RelocModel::Pic) => LinkOutputKind::StaticPicExe,
1281 (CrateType::Executable, true, _) => LinkOutputKind::StaticNoPicExe,
1282 (_, true, _) => LinkOutputKind::StaticDylib,
1283 (_, false, _) => LinkOutputKind::DynamicDylib,
1286 // Adjust the output kind to target capabilities.
1287 let opts = &sess.target;
1288 let pic_exe_supported = opts.position_independent_executables;
1289 let static_pic_exe_supported = opts.static_position_independent_executables;
1290 let static_dylib_supported = opts.crt_static_allows_dylibs;
1292 LinkOutputKind::DynamicPicExe if !pic_exe_supported => LinkOutputKind::DynamicNoPicExe,
1293 LinkOutputKind::StaticPicExe if !static_pic_exe_supported => LinkOutputKind::StaticNoPicExe,
1294 LinkOutputKind::StaticDylib if !static_dylib_supported => LinkOutputKind::DynamicDylib,
1299 // Returns true if linker is located within sysroot
1300 fn detect_self_contained_mingw(sess: &Session) -> bool {
1301 let (linker, _) = linker_and_flavor(&sess);
1302 // Assume `-C linker=rust-lld` as self-contained mode
1303 if linker == Path::new("rust-lld") {
1306 let linker_with_extension = if cfg!(windows) && linker.extension().is_none() {
1307 linker.with_extension("exe")
1311 for dir in env::split_paths(&env::var_os("PATH").unwrap_or_default()) {
1312 let full_path = dir.join(&linker_with_extension);
1313 // If linker comes from sysroot assume self-contained mode
1314 if full_path.is_file() && !full_path.starts_with(&sess.sysroot) {
1321 /// Whether we link to our own CRT objects instead of relying on gcc to pull them.
1322 /// We only provide such support for a very limited number of targets.
1323 fn crt_objects_fallback(sess: &Session, crate_type: CrateType) -> bool {
1324 if let Some(self_contained) = sess.opts.cg.link_self_contained {
1325 return self_contained;
1328 match sess.target.crt_objects_fallback {
1329 // FIXME: Find a better heuristic for "native musl toolchain is available",
1330 // based on host and linker path, for example.
1331 // (https://github.com/rust-lang/rust/pull/71769#issuecomment-626330237).
1332 Some(CrtObjectsFallback::Musl) => sess.crt_static(Some(crate_type)),
1333 Some(CrtObjectsFallback::Mingw) => {
1334 sess.host == sess.target
1335 && sess.target.vendor != "uwp"
1336 && detect_self_contained_mingw(&sess)
1338 // FIXME: Figure out cases in which WASM needs to link with a native toolchain.
1339 Some(CrtObjectsFallback::Wasm) => true,
1344 /// Add pre-link object files defined by the target spec.
1345 fn add_pre_link_objects(
1346 cmd: &mut dyn Linker,
1348 link_output_kind: LinkOutputKind,
1349 self_contained: bool,
1351 let opts = &sess.target;
1353 if self_contained { &opts.pre_link_objects_fallback } else { &opts.pre_link_objects };
1354 for obj in objects.get(&link_output_kind).iter().copied().flatten() {
1355 cmd.add_object(&get_object_file_path(sess, obj, self_contained));
1359 /// Add post-link object files defined by the target spec.
1360 fn add_post_link_objects(
1361 cmd: &mut dyn Linker,
1363 link_output_kind: LinkOutputKind,
1364 self_contained: bool,
1366 let opts = &sess.target;
1368 if self_contained { &opts.post_link_objects_fallback } else { &opts.post_link_objects };
1369 for obj in objects.get(&link_output_kind).iter().copied().flatten() {
1370 cmd.add_object(&get_object_file_path(sess, obj, self_contained));
1374 /// Add arbitrary "pre-link" args defined by the target spec or from command line.
1375 /// FIXME: Determine where exactly these args need to be inserted.
1376 fn add_pre_link_args(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavor) {
1377 if let Some(args) = sess.target.pre_link_args.get(&flavor) {
1380 cmd.args(&sess.opts.debugging_opts.pre_link_args);
1383 /// Add a link script embedded in the target, if applicable.
1384 fn add_link_script(cmd: &mut dyn Linker, sess: &Session, tmpdir: &Path, crate_type: CrateType) {
1385 match (crate_type, &sess.target.link_script) {
1386 (CrateType::Cdylib | CrateType::Executable, Some(script)) => {
1387 if !sess.target.linker_is_gnu {
1388 sess.fatal("can only use link script when linking with GNU-like linker");
1391 let file_name = ["rustc", &sess.target.llvm_target, "linkfile.ld"].join("-");
1393 let path = tmpdir.join(file_name);
1394 if let Err(e) = fs::write(&path, script) {
1395 sess.fatal(&format!("failed to write link script to {}: {}", path.display(), e));
1398 cmd.arg("--script");
1405 /// Add arbitrary "user defined" args defined from command line and by `#[link_args]` attributes.
1406 /// FIXME: Determine where exactly these args need to be inserted.
1407 fn add_user_defined_link_args(
1408 cmd: &mut dyn Linker,
1410 codegen_results: &CodegenResults,
1412 cmd.args(&sess.opts.cg.link_args);
1413 cmd.args(&*codegen_results.crate_info.link_args);
1416 /// Add arbitrary "late link" args defined by the target spec.
1417 /// FIXME: Determine where exactly these args need to be inserted.
1418 fn add_late_link_args(
1419 cmd: &mut dyn Linker,
1421 flavor: LinkerFlavor,
1422 crate_type: CrateType,
1423 codegen_results: &CodegenResults,
1425 let any_dynamic_crate = crate_type == CrateType::Dylib
1426 || codegen_results.crate_info.dependency_formats.iter().any(|(ty, list)| {
1427 *ty == crate_type && list.iter().any(|&linkage| linkage == Linkage::Dynamic)
1429 if any_dynamic_crate {
1430 if let Some(args) = sess.target.late_link_args_dynamic.get(&flavor) {
1434 if let Some(args) = sess.target.late_link_args_static.get(&flavor) {
1438 if let Some(args) = sess.target.late_link_args.get(&flavor) {
1443 /// Add arbitrary "post-link" args defined by the target spec.
1444 /// FIXME: Determine where exactly these args need to be inserted.
1445 fn add_post_link_args(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavor) {
1446 if let Some(args) = sess.target.post_link_args.get(&flavor) {
1451 /// Add object files containing code from the current crate.
1452 fn add_local_crate_regular_objects(cmd: &mut dyn Linker, codegen_results: &CodegenResults) {
1453 for obj in codegen_results.modules.iter().filter_map(|m| m.object.as_ref()) {
1454 cmd.add_object(obj);
1458 /// Add object files for allocator code linked once for the whole crate tree.
1459 fn add_local_crate_allocator_objects(cmd: &mut dyn Linker, codegen_results: &CodegenResults) {
1460 if let Some(obj) = codegen_results.allocator_module.as_ref().and_then(|m| m.object.as_ref()) {
1461 cmd.add_object(obj);
1465 /// Add object files containing metadata for the current crate.
1466 fn add_local_crate_metadata_objects(
1467 cmd: &mut dyn Linker,
1468 crate_type: CrateType,
1469 codegen_results: &CodegenResults,
1471 // When linking a dynamic library, we put the metadata into a section of the
1472 // executable. This metadata is in a separate object file from the main
1473 // object file, so we link that in here.
1474 if crate_type == CrateType::Dylib || crate_type == CrateType::ProcMacro {
1475 if let Some(obj) = codegen_results.metadata_module.as_ref().and_then(|m| m.object.as_ref())
1477 cmd.add_object(obj);
1482 /// Link native libraries corresponding to the current crate and all libraries corresponding to
1483 /// all its dependency crates.
1484 /// FIXME: Consider combining this with the functions above adding object files for the local crate.
1485 fn link_local_crate_native_libs_and_dependent_crate_libs<'a, B: ArchiveBuilder<'a>>(
1486 cmd: &mut dyn Linker,
1488 crate_type: CrateType,
1489 codegen_results: &CodegenResults,
1492 // Take careful note of the ordering of the arguments we pass to the linker
1493 // here. Linkers will assume that things on the left depend on things to the
1494 // right. Things on the right cannot depend on things on the left. This is
1495 // all formally implemented in terms of resolving symbols (libs on the right
1496 // resolve unknown symbols of libs on the left, but not vice versa).
1498 // For this reason, we have organized the arguments we pass to the linker as
1501 // 1. The local object that LLVM just generated
1502 // 2. Local native libraries
1503 // 3. Upstream rust libraries
1504 // 4. Upstream native libraries
1506 // The rationale behind this ordering is that those items lower down in the
1507 // list can't depend on items higher up in the list. For example nothing can
1508 // depend on what we just generated (e.g., that'd be a circular dependency).
1509 // Upstream rust libraries are not allowed to depend on our local native
1510 // libraries as that would violate the structure of the DAG, in that
1511 // scenario they are required to link to them as well in a shared fashion.
1513 // Note that upstream rust libraries may contain native dependencies as
1514 // well, but they also can't depend on what we just started to add to the
1515 // link line. And finally upstream native libraries can't depend on anything
1516 // in this DAG so far because they're only dylibs and dylibs can only depend
1517 // on other dylibs (e.g., other native deps).
1519 // If -Zlink-native-libraries=false is set, then the assumption is that an
1520 // external build system already has the native dependencies defined, and it
1521 // will provide them to the linker itself.
1522 if sess.opts.debugging_opts.link_native_libraries {
1523 add_local_native_libraries(cmd, sess, codegen_results);
1525 add_upstream_rust_crates::<B>(cmd, sess, codegen_results, crate_type, tmpdir);
1526 if sess.opts.debugging_opts.link_native_libraries {
1527 add_upstream_native_libraries(cmd, sess, codegen_results, crate_type);
1531 /// Add sysroot and other globally set directories to the directory search list.
1532 fn add_library_search_dirs(cmd: &mut dyn Linker, sess: &Session, self_contained: bool) {
1533 // The default library location, we need this to find the runtime.
1534 // The location of crates will be determined as needed.
1535 let lib_path = sess.target_filesearch(PathKind::All).get_lib_path();
1536 cmd.include_path(&fix_windows_verbatim_for_gcc(&lib_path));
1538 // Special directory with libraries used only in self-contained linkage mode
1540 let lib_path = sess.target_filesearch(PathKind::All).get_self_contained_lib_path();
1541 cmd.include_path(&fix_windows_verbatim_for_gcc(&lib_path));
1545 /// Add options making relocation sections in the produced ELF files read-only
1546 /// and suppressing lazy binding.
1547 fn add_relro_args(cmd: &mut dyn Linker, sess: &Session) {
1548 match sess.opts.debugging_opts.relro_level.unwrap_or(sess.target.relro_level) {
1549 RelroLevel::Full => cmd.full_relro(),
1550 RelroLevel::Partial => cmd.partial_relro(),
1551 RelroLevel::Off => cmd.no_relro(),
1552 RelroLevel::None => {}
1556 /// Add library search paths used at runtime by dynamic linkers.
1558 cmd: &mut dyn Linker,
1560 codegen_results: &CodegenResults,
1561 out_filename: &Path,
1563 // FIXME (#2397): At some point we want to rpath our guesses as to
1564 // where extern libraries might live, based on the
1565 // addl_lib_search_paths
1566 if sess.opts.cg.rpath {
1567 let target_triple = sess.opts.target_triple.triple();
1568 let mut get_install_prefix_lib_path = || {
1569 let install_prefix = option_env!("CFG_PREFIX").expect("CFG_PREFIX");
1570 let tlib = filesearch::relative_target_lib_path(&sess.sysroot, target_triple);
1571 let mut path = PathBuf::from(install_prefix);
1576 let mut rpath_config = RPathConfig {
1577 used_crates: &codegen_results.crate_info.used_crates_dynamic,
1578 out_filename: out_filename.to_path_buf(),
1579 has_rpath: sess.target.has_rpath,
1580 is_like_osx: sess.target.is_like_osx,
1581 linker_is_gnu: sess.target.linker_is_gnu,
1582 get_install_prefix_lib_path: &mut get_install_prefix_lib_path,
1584 cmd.args(&rpath::get_rpath_flags(&mut rpath_config));
1588 /// Produce the linker command line containing linker path and arguments.
1589 /// `NO-OPT-OUT` marks the arguments that cannot be removed from the command line
1590 /// by the user without creating a custom target specification.
1591 /// `OBJECT-FILES` specify whether the arguments can add object files.
1592 /// `CUSTOMIZATION-POINT` means that arbitrary arguments defined by the user
1593 /// or by the target spec can be inserted here.
1594 /// `AUDIT-ORDER` - need to figure out whether the option is order-dependent or not.
1595 fn linker_with_args<'a, B: ArchiveBuilder<'a>>(
1597 flavor: LinkerFlavor,
1599 crate_type: CrateType,
1601 out_filename: &Path,
1602 codegen_results: &CodegenResults,
1605 let crt_objects_fallback = crt_objects_fallback(sess, crate_type);
1606 let base_cmd = get_linker(sess, path, flavor, crt_objects_fallback);
1607 // FIXME: Move `/LIBPATH` addition for uwp targets from the linker construction
1608 // to the linker args construction.
1609 assert!(base_cmd.get_args().is_empty() || sess.target.vendor == "uwp");
1610 let cmd = &mut *codegen_results.linker_info.to_linker(base_cmd, &sess, flavor, target_cpu);
1611 let link_output_kind = link_output_kind(sess, crate_type);
1613 // NO-OPT-OUT, OBJECT-FILES-MAYBE, CUSTOMIZATION-POINT
1614 add_pre_link_args(cmd, sess, flavor);
1616 // NO-OPT-OUT, OBJECT-FILES-NO
1617 add_apple_sdk(cmd, sess, flavor);
1620 add_link_script(cmd, sess, tmpdir, crate_type);
1622 // NO-OPT-OUT, OBJECT-FILES-NO, AUDIT-ORDER
1623 if sess.target.is_like_fuchsia && crate_type == CrateType::Executable {
1624 let prefix = if sess.opts.debugging_opts.sanitizer.contains(SanitizerSet::ADDRESS) {
1629 cmd.arg(format!("--dynamic-linker={}ld.so.1", prefix));
1632 // NO-OPT-OUT, OBJECT-FILES-NO, AUDIT-ORDER
1633 if sess.target.eh_frame_header {
1634 cmd.add_eh_frame_header();
1637 // NO-OPT-OUT, OBJECT-FILES-NO
1638 if crt_objects_fallback {
1639 cmd.no_crt_objects();
1642 // NO-OPT-OUT, OBJECT-FILES-YES
1643 add_pre_link_objects(cmd, sess, link_output_kind, crt_objects_fallback);
1645 // NO-OPT-OUT, OBJECT-FILES-NO, AUDIT-ORDER
1646 if sess.target.is_like_emscripten {
1648 cmd.arg(if sess.panic_strategy() == PanicStrategy::Abort {
1649 "DISABLE_EXCEPTION_CATCHING=1"
1651 "DISABLE_EXCEPTION_CATCHING=0"
1655 // OBJECT-FILES-YES, AUDIT-ORDER
1656 link_sanitizers(sess, crate_type, cmd);
1658 // OBJECT-FILES-NO, AUDIT-ORDER
1659 // Linker plugins should be specified early in the list of arguments
1660 // FIXME: How "early" exactly?
1661 cmd.linker_plugin_lto();
1663 // NO-OPT-OUT, OBJECT-FILES-NO, AUDIT-ORDER
1664 // FIXME: Order-dependent, at least relatively to other args adding searh directories.
1665 add_library_search_dirs(cmd, sess, crt_objects_fallback);
1668 add_local_crate_regular_objects(cmd, codegen_results);
1670 // NO-OPT-OUT, OBJECT-FILES-NO, AUDIT-ORDER
1671 cmd.output_filename(out_filename);
1673 // OBJECT-FILES-NO, AUDIT-ORDER
1674 if crate_type == CrateType::Executable && sess.target.is_like_windows {
1675 if let Some(ref s) = codegen_results.windows_subsystem {
1680 // NO-OPT-OUT, OBJECT-FILES-NO, AUDIT-ORDER
1681 // If we're building something like a dynamic library then some platforms
1682 // need to make sure that all symbols are exported correctly from the
1684 cmd.export_symbols(tmpdir, crate_type);
1687 add_local_crate_metadata_objects(cmd, crate_type, codegen_results);
1690 add_local_crate_allocator_objects(cmd, codegen_results);
1692 // OBJECT-FILES-NO, AUDIT-ORDER
1693 // FIXME: Order dependent, applies to the following objects. Where should it be placed?
1694 // Try to strip as much out of the generated object by removing unused
1695 // sections if possible. See more comments in linker.rs
1696 if !sess.link_dead_code() {
1697 let keep_metadata = crate_type == CrateType::Dylib;
1698 cmd.gc_sections(keep_metadata);
1701 // NO-OPT-OUT, OBJECT-FILES-NO, AUDIT-ORDER
1702 cmd.set_output_kind(link_output_kind, out_filename);
1704 // OBJECT-FILES-NO, AUDIT-ORDER
1705 add_relro_args(cmd, sess);
1707 // OBJECT-FILES-NO, AUDIT-ORDER
1708 // Pass optimization flags down to the linker.
1711 // OBJECT-FILES-NO, AUDIT-ORDER
1712 // Pass debuginfo and strip flags down to the linker.
1713 cmd.debuginfo(sess.opts.debugging_opts.strip);
1715 // OBJECT-FILES-NO, AUDIT-ORDER
1716 // We want to prevent the compiler from accidentally leaking in any system libraries,
1717 // so by default we tell linkers not to link to any default libraries.
1718 if !sess.opts.cg.default_linker_libraries && sess.target.no_default_libraries {
1719 cmd.no_default_libraries();
1723 link_local_crate_native_libs_and_dependent_crate_libs::<B>(
1731 // OBJECT-FILES-NO, AUDIT-ORDER
1732 if sess.opts.cg.profile_generate.enabled() || sess.opts.debugging_opts.instrument_coverage {
1736 // OBJECT-FILES-NO, AUDIT-ORDER
1737 if sess.opts.cg.control_flow_guard != CFGuard::Disabled {
1738 cmd.control_flow_guard();
1741 // OBJECT-FILES-NO, AUDIT-ORDER
1742 add_rpath_args(cmd, sess, codegen_results, out_filename);
1744 // OBJECT-FILES-MAYBE, CUSTOMIZATION-POINT
1745 add_user_defined_link_args(cmd, sess, codegen_results);
1747 // NO-OPT-OUT, OBJECT-FILES-NO, AUDIT-ORDER
1750 // NO-OPT-OUT, OBJECT-FILES-MAYBE, CUSTOMIZATION-POINT
1751 add_late_link_args(cmd, sess, flavor, crate_type, codegen_results);
1753 // NO-OPT-OUT, OBJECT-FILES-YES
1754 add_post_link_objects(cmd, sess, link_output_kind, crt_objects_fallback);
1756 // NO-OPT-OUT, OBJECT-FILES-MAYBE, CUSTOMIZATION-POINT
1757 add_post_link_args(cmd, sess, flavor);
1762 /// # Native library linking
1764 /// User-supplied library search paths (-L on the command line). These are the same paths used to
1765 /// find Rust crates, so some of them may have been added already by the previous crate linking
1766 /// code. This only allows them to be found at compile time so it is still entirely up to outside
1767 /// forces to make sure that library can be found at runtime.
1769 /// Also note that the native libraries linked here are only the ones located in the current crate.
1770 /// Upstream crates with native library dependencies may have their native library pulled in above.
1771 fn add_local_native_libraries(
1772 cmd: &mut dyn Linker,
1774 codegen_results: &CodegenResults,
1776 let filesearch = sess.target_filesearch(PathKind::All);
1777 for search_path in filesearch.search_paths() {
1778 match search_path.kind {
1779 PathKind::Framework => {
1780 cmd.framework_path(&search_path.dir);
1783 cmd.include_path(&fix_windows_verbatim_for_gcc(&search_path.dir));
1789 codegen_results.crate_info.used_libraries.iter().filter(|l| relevant_lib(sess, l));
1791 let search_path = archive_search_paths(sess);
1792 for lib in relevant_libs {
1793 let name = match lib.name {
1798 NativeLibKind::Dylib | NativeLibKind::Unspecified => cmd.link_dylib(name),
1799 NativeLibKind::Framework => cmd.link_framework(name),
1800 NativeLibKind::StaticNoBundle => cmd.link_staticlib(name),
1801 NativeLibKind::StaticBundle => cmd.link_whole_staticlib(name, &search_path),
1802 NativeLibKind::RawDylib => {
1803 // FIXME(#58713): Proper handling for raw dylibs.
1804 bug!("raw_dylib feature not yet implemented");
1810 /// # Rust Crate linking
1812 /// Rust crates are not considered at all when creating an rlib output. All dependencies will be
1813 /// linked when producing the final output (instead of the intermediate rlib version).
1814 fn add_upstream_rust_crates<'a, B: ArchiveBuilder<'a>>(
1815 cmd: &mut dyn Linker,
1817 codegen_results: &CodegenResults,
1818 crate_type: CrateType,
1821 // All of the heavy lifting has previously been accomplished by the
1822 // dependency_format module of the compiler. This is just crawling the
1823 // output of that module, adding crates as necessary.
1825 // Linking to a rlib involves just passing it to the linker (the linker
1826 // will slurp up the object files inside), and linking to a dynamic library
1827 // involves just passing the right -l flag.
1829 let (_, data) = codegen_results
1833 .find(|(ty, _)| *ty == crate_type)
1834 .expect("failed to find crate type in dependency format list");
1836 // Invoke get_used_crates to ensure that we get a topological sorting of
1838 let deps = &codegen_results.crate_info.used_crates_dynamic;
1840 // There's a few internal crates in the standard library (aka libcore and
1841 // libstd) which actually have a circular dependence upon one another. This
1842 // currently arises through "weak lang items" where libcore requires things
1843 // like `rust_begin_unwind` but libstd ends up defining it. To get this
1844 // circular dependence to work correctly in all situations we'll need to be
1845 // sure to correctly apply the `--start-group` and `--end-group` options to
1846 // GNU linkers, otherwise if we don't use any other symbol from the standard
1847 // library it'll get discarded and the whole application won't link.
1849 // In this loop we're calculating the `group_end`, after which crate to
1850 // pass `--end-group` and `group_start`, before which crate to pass
1851 // `--start-group`. We currently do this by passing `--end-group` after
1852 // the first crate (when iterating backwards) that requires a lang item
1853 // defined somewhere else. Once that's set then when we've defined all the
1854 // necessary lang items we'll pass `--start-group`.
1856 // Note that this isn't amazing logic for now but it should do the trick
1857 // for the current implementation of the standard library.
1858 let mut group_end = None;
1859 let mut group_start = None;
1860 // Crates available for linking thus far.
1861 let mut available = FxHashSet::default();
1862 // Crates required to satisfy dependencies discovered so far.
1863 let mut required = FxHashSet::default();
1865 let info = &codegen_results.crate_info;
1866 for &(cnum, _) in deps.iter().rev() {
1867 if let Some(missing) = info.missing_lang_items.get(&cnum) {
1868 let missing_crates = missing.iter().map(|i| info.lang_item_to_crate.get(i).copied());
1869 required.extend(missing_crates);
1872 required.insert(Some(cnum));
1873 available.insert(Some(cnum));
1875 if required.len() > available.len() && group_end.is_none() {
1876 group_end = Some(cnum);
1878 if required.len() == available.len() && group_end.is_some() {
1879 group_start = Some(cnum);
1884 // If we didn't end up filling in all lang items from upstream crates then
1885 // we'll be filling it in with our crate. This probably means we're the
1886 // standard library itself, so skip this for now.
1887 if group_end.is_some() && group_start.is_none() {
1891 let mut compiler_builtins = None;
1893 for &(cnum, _) in deps.iter() {
1894 if group_start == Some(cnum) {
1898 // We may not pass all crates through to the linker. Some crates may
1899 // appear statically in an existing dylib, meaning we'll pick up all the
1900 // symbols from the dylib.
1901 let src = &codegen_results.crate_info.used_crate_source[&cnum];
1902 match data[cnum.as_usize() - 1] {
1903 _ if codegen_results.crate_info.profiler_runtime == Some(cnum) => {
1904 add_static_crate::<B>(cmd, sess, codegen_results, tmpdir, crate_type, cnum);
1906 // compiler-builtins are always placed last to ensure that they're
1907 // linked correctly.
1908 _ if codegen_results.crate_info.compiler_builtins == Some(cnum) => {
1909 assert!(compiler_builtins.is_none());
1910 compiler_builtins = Some(cnum);
1912 Linkage::NotLinked | Linkage::IncludedFromDylib => {}
1913 Linkage::Static => {
1914 add_static_crate::<B>(cmd, sess, codegen_results, tmpdir, crate_type, cnum);
1916 Linkage::Dynamic => add_dynamic_crate(cmd, sess, &src.dylib.as_ref().unwrap().0),
1919 if group_end == Some(cnum) {
1924 // compiler-builtins are always placed last to ensure that they're
1925 // linked correctly.
1926 // We must always link the `compiler_builtins` crate statically. Even if it
1927 // was already "included" in a dylib (e.g., `libstd` when `-C prefer-dynamic`
1929 if let Some(cnum) = compiler_builtins {
1930 add_static_crate::<B>(cmd, sess, codegen_results, tmpdir, crate_type, cnum);
1933 // Converts a library file-stem into a cc -l argument
1934 fn unlib<'a>(target: &Target, stem: &'a str) -> &'a str {
1935 if stem.starts_with("lib") && !target.is_like_windows { &stem[3..] } else { stem }
1938 // Adds the static "rlib" versions of all crates to the command line.
1939 // There's a bit of magic which happens here specifically related to LTO and
1940 // dynamic libraries. Specifically:
1942 // * For LTO, we remove upstream object files.
1943 // * For dylibs we remove metadata and bytecode from upstream rlibs
1945 // When performing LTO, almost(*) all of the bytecode from the upstream
1946 // libraries has already been included in our object file output. As a
1947 // result we need to remove the object files in the upstream libraries so
1948 // the linker doesn't try to include them twice (or whine about duplicate
1949 // symbols). We must continue to include the rest of the rlib, however, as
1950 // it may contain static native libraries which must be linked in.
1952 // (*) Crates marked with `#![no_builtins]` don't participate in LTO and
1953 // their bytecode wasn't included. The object files in those libraries must
1954 // still be passed to the linker.
1956 // When making a dynamic library, linkers by default don't include any
1957 // object files in an archive if they're not necessary to resolve the link.
1958 // We basically want to convert the archive (rlib) to a dylib, though, so we
1959 // *do* want everything included in the output, regardless of whether the
1960 // linker thinks it's needed or not. As a result we must use the
1961 // --whole-archive option (or the platform equivalent). When using this
1962 // option the linker will fail if there are non-objects in the archive (such
1963 // as our own metadata and/or bytecode). All in all, for rlibs to be
1964 // entirely included in dylibs, we need to remove all non-object files.
1966 // Note, however, that if we're not doing LTO or we're not producing a dylib
1967 // (aka we're making an executable), we can just pass the rlib blindly to
1968 // the linker (fast) because it's fine if it's not actually included as
1969 // we're at the end of the dependency chain.
1970 fn add_static_crate<'a, B: ArchiveBuilder<'a>>(
1971 cmd: &mut dyn Linker,
1973 codegen_results: &CodegenResults,
1975 crate_type: CrateType,
1978 let src = &codegen_results.crate_info.used_crate_source[&cnum];
1979 let cratepath = &src.rlib.as_ref().unwrap().0;
1981 // See the comment above in `link_staticlib` and `link_rlib` for why if
1982 // there's a static library that's not relevant we skip all object
1984 let native_libs = &codegen_results.crate_info.native_libraries[&cnum];
1985 let skip_native = native_libs
1987 .any(|lib| lib.kind == NativeLibKind::StaticBundle && !relevant_lib(sess, lib));
1989 if (!are_upstream_rust_objects_already_included(sess)
1990 || ignored_for_lto(sess, &codegen_results.crate_info, cnum))
1991 && crate_type != CrateType::Dylib
1994 cmd.link_rlib(&fix_windows_verbatim_for_gcc(cratepath));
1998 let dst = tmpdir.join(cratepath.file_name().unwrap());
1999 let name = cratepath.file_name().unwrap().to_str().unwrap();
2000 let name = &name[3..name.len() - 5]; // chop off lib/.rlib
2002 sess.prof.generic_activity_with_arg("link_altering_rlib", name).run(|| {
2003 let mut archive = <B as ArchiveBuilder>::new(sess, &dst, Some(cratepath));
2004 archive.update_symbols();
2006 let mut any_objects = false;
2007 for f in archive.src_files() {
2008 if f == METADATA_FILENAME {
2009 archive.remove_file(&f);
2013 let canonical = f.replace("-", "_");
2014 let canonical_name = name.replace("-", "_");
2016 let is_rust_object =
2017 canonical.starts_with(&canonical_name) && looks_like_rust_object_file(&f);
2019 // If we've been requested to skip all native object files
2020 // (those not generated by the rust compiler) then we can skip
2021 // this file. See above for why we may want to do this.
2022 let skip_because_cfg_say_so = skip_native && !is_rust_object;
2024 // If we're performing LTO and this is a rust-generated object
2025 // file, then we don't need the object file as it's part of the
2026 // LTO module. Note that `#![no_builtins]` is excluded from LTO,
2027 // though, so we let that object file slide.
2028 let skip_because_lto = are_upstream_rust_objects_already_included(sess)
2030 && (sess.target.no_builtins
2031 || !codegen_results.crate_info.is_no_builtins.contains(&cnum));
2033 if skip_because_cfg_say_so || skip_because_lto {
2034 archive.remove_file(&f);
2045 // If we're creating a dylib, then we need to include the
2046 // whole of each object in our archive into that artifact. This is
2047 // because a `dylib` can be reused as an intermediate artifact.
2049 // Note, though, that we don't want to include the whole of a
2050 // compiler-builtins crate (e.g., compiler-rt) because it'll get
2051 // repeatedly linked anyway.
2052 if crate_type == CrateType::Dylib
2053 && codegen_results.crate_info.compiler_builtins != Some(cnum)
2055 cmd.link_whole_rlib(&fix_windows_verbatim_for_gcc(&dst));
2057 cmd.link_rlib(&fix_windows_verbatim_for_gcc(&dst));
2062 // Same thing as above, but for dynamic crates instead of static crates.
2063 fn add_dynamic_crate(cmd: &mut dyn Linker, sess: &Session, cratepath: &Path) {
2064 // Just need to tell the linker about where the library lives and
2066 let parent = cratepath.parent();
2067 if let Some(dir) = parent {
2068 cmd.include_path(&fix_windows_verbatim_for_gcc(dir));
2070 let filestem = cratepath.file_stem().unwrap().to_str().unwrap();
2071 cmd.link_rust_dylib(
2072 Symbol::intern(&unlib(&sess.target, filestem)),
2073 parent.unwrap_or(Path::new("")),
2078 /// Link in all of our upstream crates' native dependencies. Remember that all of these upstream
2079 /// native dependencies are all non-static dependencies. We've got two cases then:
2081 /// 1. The upstream crate is an rlib. In this case we *must* link in the native dependency because
2082 /// the rlib is just an archive.
2084 /// 2. The upstream crate is a dylib. In order to use the dylib, we have to have the dependency
2085 /// present on the system somewhere. Thus, we don't gain a whole lot from not linking in the
2086 /// dynamic dependency to this crate as well.
2088 /// The use case for this is a little subtle. In theory the native dependencies of a crate are
2089 /// purely an implementation detail of the crate itself, but the problem arises with generic and
2090 /// inlined functions. If a generic function calls a native function, then the generic function
2091 /// must be instantiated in the target crate, meaning that the native symbol must also be resolved
2092 /// in the target crate.
2093 fn add_upstream_native_libraries(
2094 cmd: &mut dyn Linker,
2096 codegen_results: &CodegenResults,
2097 crate_type: CrateType,
2099 // Be sure to use a topological sorting of crates because there may be
2100 // interdependencies between native libraries. When passing -nodefaultlibs,
2101 // for example, almost all native libraries depend on libc, so we have to
2102 // make sure that's all the way at the right (liblibc is near the base of
2103 // the dependency chain).
2105 // This passes RequireStatic, but the actual requirement doesn't matter,
2106 // we're just getting an ordering of crate numbers, we're not worried about
2108 let (_, data) = codegen_results
2112 .find(|(ty, _)| *ty == crate_type)
2113 .expect("failed to find crate type in dependency format list");
2115 let crates = &codegen_results.crate_info.used_crates_static;
2116 for &(cnum, _) in crates {
2117 for lib in codegen_results.crate_info.native_libraries[&cnum].iter() {
2118 let name = match lib.name {
2122 if !relevant_lib(sess, &lib) {
2126 NativeLibKind::Dylib | NativeLibKind::Unspecified => cmd.link_dylib(name),
2127 NativeLibKind::Framework => cmd.link_framework(name),
2128 NativeLibKind::StaticNoBundle => {
2129 // Link "static-nobundle" native libs only if the crate they originate from
2130 // is being linked statically to the current crate. If it's linked dynamically
2131 // or is an rlib already included via some other dylib crate, the symbols from
2132 // native libs will have already been included in that dylib.
2133 if data[cnum.as_usize() - 1] == Linkage::Static {
2134 cmd.link_staticlib(name)
2137 // ignore statically included native libraries here as we've
2138 // already included them when we included the rust library
2140 NativeLibKind::StaticBundle => {}
2141 NativeLibKind::RawDylib => {
2142 // FIXME(#58713): Proper handling for raw dylibs.
2143 bug!("raw_dylib feature not yet implemented");
2150 fn relevant_lib(sess: &Session, lib: &NativeLib) -> bool {
2152 Some(ref cfg) => rustc_attr::cfg_matches(cfg, &sess.parse_sess, None),
2157 fn are_upstream_rust_objects_already_included(sess: &Session) -> bool {
2159 config::Lto::Fat => true,
2160 config::Lto::Thin => {
2161 // If we defer LTO to the linker, we haven't run LTO ourselves, so
2162 // any upstream object files have not been copied yet.
2163 !sess.opts.cg.linker_plugin_lto.enabled()
2165 config::Lto::No | config::Lto::ThinLocal => false,
2169 fn add_apple_sdk(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavor) {
2170 let arch = &sess.target.arch;
2171 let os = &sess.target.os;
2172 let llvm_target = &sess.target.llvm_target;
2173 if sess.target.vendor != "apple"
2174 || !matches!(os.as_str(), "ios" | "tvos")
2175 || flavor != LinkerFlavor::Gcc
2179 let sdk_name = match (arch.as_str(), os.as_str()) {
2180 ("aarch64", "tvos") => "appletvos",
2181 ("x86_64", "tvos") => "appletvsimulator",
2182 ("arm", "ios") => "iphoneos",
2183 ("aarch64", "ios") if llvm_target.contains("macabi") => "macosx",
2184 ("aarch64", "ios") => "iphoneos",
2185 ("x86", "ios") => "iphonesimulator",
2186 ("x86_64", "ios") if llvm_target.contains("macabi") => "macosx",
2187 ("x86_64", "ios") => "iphonesimulator",
2189 sess.err(&format!("unsupported arch `{}` for os `{}`", arch, os));
2193 let sdk_root = match get_apple_sdk_root(sdk_name) {
2200 let arch_name = llvm_target.split('-').next().expect("LLVM target must have a hyphen");
2201 cmd.args(&["-arch", arch_name, "-isysroot", &sdk_root, "-Wl,-syslibroot", &sdk_root]);
2204 fn get_apple_sdk_root(sdk_name: &str) -> Result<String, String> {
2205 // Following what clang does
2206 // (https://github.com/llvm/llvm-project/blob/
2207 // 296a80102a9b72c3eda80558fb78a3ed8849b341/clang/lib/Driver/ToolChains/Darwin.cpp#L1661-L1678)
2208 // to allow the SDK path to be set. (For clang, xcrun sets
2209 // SDKROOT; for rustc, the user or build system can set it, or we
2210 // can fall back to checking for xcrun on PATH.)
2211 if let Ok(sdkroot) = env::var("SDKROOT") {
2212 let p = Path::new(&sdkroot);
2214 // Ignore `SDKROOT` if it's clearly set for the wrong platform.
2216 if sdkroot.contains("TVSimulator.platform")
2217 || sdkroot.contains("MacOSX.platform") => {}
2219 if sdkroot.contains("TVOS.platform") || sdkroot.contains("MacOSX.platform") => {}
2221 if sdkroot.contains("iPhoneSimulator.platform")
2222 || sdkroot.contains("MacOSX.platform") => {}
2224 if sdkroot.contains("iPhoneOS.platform") || sdkroot.contains("MacOSX.platform") => {
2227 if sdkroot.contains("iPhoneOS.platform")
2228 || sdkroot.contains("iPhoneSimulator.platform") => {}
2229 // Ignore `SDKROOT` if it's not a valid path.
2230 _ if !p.is_absolute() || p == Path::new("/") || !p.exists() => {}
2231 _ => return Ok(sdkroot),
2235 Command::new("xcrun").arg("--show-sdk-path").arg("-sdk").arg(sdk_name).output().and_then(
2237 if output.status.success() {
2238 Ok(String::from_utf8(output.stdout).unwrap())
2240 let error = String::from_utf8(output.stderr);
2241 let error = format!("process exit with error: {}", error.unwrap());
2242 Err(io::Error::new(io::ErrorKind::Other, &error[..]))
2248 Ok(output) => Ok(output.trim().to_string()),
2249 Err(e) => Err(format!("failed to get {} SDK path: {}", sdk_name, e)),