1 use rustc_data_structures::fx::FxHashSet;
2 use rustc_data_structures::temp_dir::MaybeTempDir;
3 use rustc_errors::Handler;
4 use rustc_fs_util::fix_windows_verbatim_for_gcc;
5 use rustc_hir::def_id::CrateNum;
6 use rustc_middle::middle::cstore::{EncodedMetadata, LibSource};
7 use rustc_middle::middle::dependency_format::Linkage;
8 use rustc_session::config::{self, CFGuard, CrateType, DebugInfo};
9 use rustc_session::config::{OutputFilenames, OutputType, PrintRequest};
10 use rustc_session::output::{check_file_is_writeable, invalid_output_for_target, out_filename};
11 use rustc_session::search_paths::PathKind;
12 use rustc_session::utils::NativeLibKind;
13 /// For all the linkers we support, and information they might
14 /// need out of the shared crate context before we get rid of it.
15 use rustc_session::{filesearch, Session};
16 use rustc_span::symbol::Symbol;
17 use rustc_target::spec::crt_objects::{CrtObjects, CrtObjectsFallback};
18 use rustc_target::spec::{LinkOutputKind, LinkerFlavor, LldFlavor, SplitDebuginfo};
19 use rustc_target::spec::{PanicStrategy, RelocModel, RelroLevel, SanitizerSet, Target};
21 use super::archive::ArchiveBuilder;
22 use super::command::Command;
23 use super::linker::{self, Linker};
24 use super::rpath::{self, RPathConfig};
26 looks_like_rust_object_file, CodegenResults, CompiledModule, CrateInfo, NativeLib,
30 use cc::windows_registry;
31 use tempfile::Builder as TempFileBuilder;
33 use std::ffi::OsString;
34 use std::path::{Path, PathBuf};
35 use std::process::{ExitStatus, Output, Stdio};
36 use std::{ascii, char, env, fmt, fs, io, mem, str};
38 pub fn ensure_removed(diag_handler: &Handler, path: &Path) {
39 if let Err(e) = fs::remove_file(path) {
40 if e.kind() != io::ErrorKind::NotFound {
41 diag_handler.err(&format!("failed to remove {}: {}", path.display(), e));
46 /// Performs the linkage portion of the compilation phase. This will generate all
47 /// of the requested outputs for this compilation session.
48 pub fn link_binary<'a, B: ArchiveBuilder<'a>>(
50 codegen_results: &CodegenResults,
51 outputs: &OutputFilenames,
54 let _timer = sess.timer("link_binary");
55 let output_metadata = sess.opts.output_types.contains_key(&OutputType::Metadata);
56 for &crate_type in sess.crate_types().iter() {
57 // Ignore executable crates if we have -Z no-codegen, as they will error.
58 if (sess.opts.debugging_opts.no_codegen || !sess.opts.output_types.should_codegen())
60 && crate_type == CrateType::Executable
65 if invalid_output_for_target(sess, crate_type) {
67 "invalid output type `{:?}` for target os `{}`",
69 sess.opts.target_triple
73 sess.time("link_binary_check_files_are_writeable", || {
74 for obj in codegen_results.modules.iter().filter_map(|m| m.object.as_ref()) {
75 check_file_is_writeable(obj, sess);
79 if outputs.outputs.should_link() {
80 let tmpdir = TempFileBuilder::new()
83 .unwrap_or_else(|err| sess.fatal(&format!("couldn't create a temp dir: {}", err)));
84 let path = MaybeTempDir::new(tmpdir, sess.opts.cg.save_temps);
85 let out_filename = out_filename(sess, crate_type, outputs, crate_name);
88 let _timer = sess.timer("link_rlib");
89 link_rlib::<B>(sess, codegen_results, RlibFlavor::Normal, &out_filename, &path)
92 CrateType::Staticlib => {
93 link_staticlib::<B>(sess, codegen_results, &out_filename, &path);
105 if sess.opts.json_artifact_notifications {
106 sess.parse_sess.span_diagnostic.emit_artifact_notification(&out_filename, "link");
111 // Remove the temporary object file and metadata if we aren't saving temps
112 sess.time("link_binary_remove_temps", || {
113 if !sess.opts.cg.save_temps {
114 let remove_temps_from_module = |module: &CompiledModule| {
115 if let Some(ref obj) = module.object {
116 ensure_removed(sess.diagnostic(), obj);
119 if let Some(ref obj) = module.dwarf_object {
120 ensure_removed(sess.diagnostic(), obj);
124 if sess.opts.output_types.should_link() && !preserve_objects_for_their_debuginfo(sess) {
125 for module in &codegen_results.modules {
126 remove_temps_from_module(module);
130 if let Some(ref metadata_module) = codegen_results.metadata_module {
131 remove_temps_from_module(metadata_module);
134 if let Some(ref allocator_module) = codegen_results.allocator_module {
135 remove_temps_from_module(allocator_module);
141 // The third parameter is for env vars, used on windows to set up the
142 // path for MSVC to find its DLLs, and gcc to find its bundled
147 flavor: LinkerFlavor,
148 self_contained: bool,
150 let msvc_tool = windows_registry::find_tool(&sess.opts.target_triple.triple(), "link.exe");
152 // If our linker looks like a batch script on Windows then to execute this
153 // we'll need to spawn `cmd` explicitly. This is primarily done to handle
154 // emscripten where the linker is `emcc.bat` and needs to be spawned as
155 // `cmd /c emcc.bat ...`.
157 // This worked historically but is needed manually since #42436 (regression
158 // was tagged as #42791) and some more info can be found on #44443 for
159 // emscripten itself.
160 let mut cmd = match linker.to_str() {
161 Some(linker) if cfg!(windows) && linker.ends_with(".bat") => Command::bat_script(linker),
163 LinkerFlavor::Lld(f) => Command::lld(linker, f),
164 LinkerFlavor::Msvc if sess.opts.cg.linker.is_none() && sess.target.linker.is_none() => {
165 Command::new(msvc_tool.as_ref().map_or(linker, |t| t.path()))
167 _ => Command::new(linker),
171 // UWP apps have API restrictions enforced during Store submissions.
172 // To comply with the Windows App Certification Kit,
173 // MSVC needs to link with the Store versions of the runtime libraries (vcruntime, msvcrt, etc).
174 let t = &sess.target;
175 if (flavor == LinkerFlavor::Msvc || flavor == LinkerFlavor::Lld(LldFlavor::Link))
178 if let Some(ref tool) = msvc_tool {
179 let original_path = tool.path();
180 if let Some(ref root_lib_path) = original_path.ancestors().nth(4) {
181 let arch = match t.arch.as_str() {
182 "x86_64" => Some("x64"),
183 "x86" => Some("x86"),
184 "aarch64" => Some("arm64"),
185 "arm" => Some("arm"),
188 if let Some(ref a) = arch {
189 // FIXME: Move this to `fn linker_with_args`.
190 let mut arg = OsString::from("/LIBPATH:");
191 arg.push(format!("{}\\lib\\{}\\store", root_lib_path.display(), a));
194 warn!("arch is not supported");
197 warn!("MSVC root path lib location not found");
200 warn!("link.exe not found");
204 // The compiler's sysroot often has some bundled tools, so add it to the
205 // PATH for the child.
206 let mut new_path = sess.host_filesearch(PathKind::All).get_tools_search_paths(self_contained);
207 let mut msvc_changed_path = false;
208 if sess.target.is_like_msvc {
209 if let Some(ref tool) = msvc_tool {
210 cmd.args(tool.args());
211 for &(ref k, ref v) in tool.env() {
213 new_path.extend(env::split_paths(v));
214 msvc_changed_path = true;
222 if !msvc_changed_path {
223 if let Some(path) = env::var_os("PATH") {
224 new_path.extend(env::split_paths(&path));
227 cmd.env("PATH", env::join_paths(new_path).unwrap());
232 pub fn each_linked_rlib(
234 f: &mut dyn FnMut(CrateNum, &Path),
235 ) -> Result<(), String> {
236 let crates = info.used_crates_static.iter();
238 for (ty, list) in info.dependency_formats.iter() {
240 CrateType::Executable
241 | CrateType::Staticlib
243 | CrateType::ProcMacro => {
250 let fmts = match fmts {
252 None => return Err("could not find formats for rlibs".to_string()),
254 for &(cnum, ref path) in crates {
255 match fmts.get(cnum.as_usize() - 1) {
256 Some(&Linkage::NotLinked | &Linkage::IncludedFromDylib) => continue,
258 None => return Err("could not find formats for rlibs".to_string()),
260 let name = &info.crate_name[&cnum];
261 let path = match *path {
262 LibSource::Some(ref p) => p,
263 LibSource::MetadataOnly => {
265 "could not find rlib for: `{}`, found rmeta (metadata) file",
269 LibSource::None => return Err(format!("could not find rlib for: `{}`", name)),
276 /// We use a temp directory here to avoid races between concurrent rustc processes,
277 /// such as builds in the same directory using the same filename for metadata while
278 /// building an `.rlib` (stomping over one another), or writing an `.rmeta` into a
279 /// directory being searched for `extern crate` (observing an incomplete file).
280 /// The returned path is the temporary file containing the complete metadata.
281 pub fn emit_metadata(sess: &Session, metadata: &EncodedMetadata, tmpdir: &MaybeTempDir) -> PathBuf {
282 let out_filename = tmpdir.as_ref().join(METADATA_FILENAME);
283 let result = fs::write(&out_filename, &metadata.raw_data);
285 if let Err(e) = result {
286 sess.fatal(&format!("failed to write {}: {}", out_filename.display(), e));
292 /// Create an 'rlib'.
294 /// An rlib in its current incarnation is essentially a renamed .a file. The rlib primarily contains
295 /// the object file of the crate, but it also contains all of the object files from native
296 /// libraries. This is done by unzipping native libraries and inserting all of the contents into
298 fn link_rlib<'a, B: ArchiveBuilder<'a>>(
300 codegen_results: &CodegenResults,
303 tmpdir: &MaybeTempDir,
305 info!("preparing rlib to {:?}", out_filename);
306 let mut ab = <B as ArchiveBuilder>::new(sess, out_filename, None);
308 for obj in codegen_results.modules.iter().filter_map(|m| m.object.as_ref()) {
312 // Note that in this loop we are ignoring the value of `lib.cfg`. That is,
313 // we may not be configured to actually include a static library if we're
314 // adding it here. That's because later when we consume this rlib we'll
315 // decide whether we actually needed the static library or not.
317 // To do this "correctly" we'd need to keep track of which libraries added
318 // which object files to the archive. We don't do that here, however. The
319 // #[link(cfg(..))] feature is unstable, though, and only intended to get
320 // liblibc working. In that sense the check below just indicates that if
321 // there are any libraries we want to omit object files for at link time we
322 // just exclude all custom object files.
324 // Eventually if we want to stabilize or flesh out the #[link(cfg(..))]
325 // feature then we'll need to figure out how to record what objects were
326 // loaded from the libraries found here and then encode that into the
327 // metadata of the rlib we're generating somehow.
328 for lib in codegen_results.crate_info.used_libraries.iter() {
330 NativeLibKind::Static { bundle: None | Some(true), .. } => {}
331 NativeLibKind::Static { bundle: Some(false), .. }
332 | NativeLibKind::Dylib { .. }
333 | NativeLibKind::Framework { .. }
334 | NativeLibKind::RawDylib
335 | NativeLibKind::Unspecified => continue,
337 if let Some(name) = lib.name {
338 ab.add_native_library(name, lib.verbatim.unwrap_or(false));
342 // After adding all files to the archive, we need to update the
343 // symbol table of the archive.
346 // Note that it is important that we add all of our non-object "magical
347 // files" *after* all of the object files in the archive. The reason for
348 // this is as follows:
350 // * When performing LTO, this archive will be modified to remove
351 // objects from above. The reason for this is described below.
353 // * When the system linker looks at an archive, it will attempt to
354 // determine the architecture of the archive in order to see whether its
357 // The algorithm for this detection is: iterate over the files in the
358 // archive. Skip magical SYMDEF names. Interpret the first file as an
359 // object file. Read architecture from the object file.
361 // * As one can probably see, if "metadata" and "foo.bc" were placed
362 // before all of the objects, then the architecture of this archive would
363 // not be correctly inferred once 'foo.o' is removed.
365 // Basically, all this means is that this code should not move above the
368 RlibFlavor::Normal => {
369 // Instead of putting the metadata in an object file section, rlibs
370 // contain the metadata in a separate file.
371 ab.add_file(&emit_metadata(sess, &codegen_results.metadata, tmpdir));
373 // After adding all files to the archive, we need to update the
374 // symbol table of the archive. This currently dies on macOS (see
375 // #11162), and isn't necessary there anyway
376 if !sess.target.is_like_osx {
381 RlibFlavor::StaticlibBase => {
382 let obj = codegen_results.allocator_module.as_ref().and_then(|m| m.object.as_ref());
383 if let Some(obj) = obj {
392 /// Create a static archive.
394 /// This is essentially the same thing as an rlib, but it also involves adding all of the upstream
395 /// crates' objects into the archive. This will slurp in all of the native libraries of upstream
396 /// dependencies as well.
398 /// Additionally, there's no way for us to link dynamic libraries, so we warn about all dynamic
399 /// library dependencies that they're not linked in.
401 /// There's no need to include metadata in a static archive, so ensure to not link in the metadata
402 /// object file (and also don't prepare the archive with a metadata file).
403 fn link_staticlib<'a, B: ArchiveBuilder<'a>>(
405 codegen_results: &CodegenResults,
407 tempdir: &MaybeTempDir,
410 link_rlib::<B>(sess, codegen_results, RlibFlavor::StaticlibBase, out_filename, tempdir);
411 let mut all_native_libs = vec![];
413 let res = each_linked_rlib(&codegen_results.crate_info, &mut |cnum, path| {
414 let name = &codegen_results.crate_info.crate_name[&cnum];
415 let native_libs = &codegen_results.crate_info.native_libraries[&cnum];
417 // Here when we include the rlib into our staticlib we need to make a
418 // decision whether to include the extra object files along the way.
419 // These extra object files come from statically included native
420 // libraries, but they may be cfg'd away with #[link(cfg(..))].
422 // This unstable feature, though, only needs liblibc to work. The only
423 // use case there is where musl is statically included in liblibc.rlib,
424 // so if we don't want the included version we just need to skip it. As
425 // a result the logic here is that if *any* linked library is cfg'd away
426 // we just skip all object files.
428 // Clearly this is not sufficient for a general purpose feature, and
429 // we'd want to read from the library's metadata to determine which
430 // object files come from where and selectively skip them.
431 let skip_object_files = native_libs.iter().any(|lib| {
432 matches!(lib.kind, NativeLibKind::Static { bundle: None | Some(true), .. })
433 && !relevant_lib(sess, lib)
438 are_upstream_rust_objects_already_included(sess)
439 && !ignored_for_lto(sess, &codegen_results.crate_info, cnum),
444 all_native_libs.extend(codegen_results.crate_info.native_libraries[&cnum].iter().cloned());
446 if let Err(e) = res {
453 if !all_native_libs.is_empty() {
454 if sess.opts.prints.contains(&PrintRequest::NativeStaticLibs) {
455 print_native_static_libs(sess, &all_native_libs);
460 fn escape_stdout_stderr_string(s: &[u8]) -> String {
461 str::from_utf8(s).map(|s| s.to_owned()).unwrap_or_else(|_| {
462 let mut x = "Non-UTF-8 output: ".to_string();
463 x.extend(s.iter().flat_map(|&b| ascii::escape_default(b)).map(char::from));
468 const LLVM_DWP_EXECUTABLE: &'static str = "rust-llvm-dwp";
470 /// Invoke `llvm-dwp` (shipped alongside rustc) to link `dwo` files from Split DWARF into a `dwp`
472 fn link_dwarf_object<'a>(sess: &'a Session, executable_out_filename: &Path) {
473 info!("preparing dwp to {}.dwp", executable_out_filename.to_str().unwrap());
475 let dwp_out_filename = executable_out_filename.with_extension("dwp");
476 let mut cmd = Command::new(LLVM_DWP_EXECUTABLE);
478 cmd.arg(executable_out_filename);
480 cmd.arg(&dwp_out_filename);
482 let mut new_path = sess.host_filesearch(PathKind::All).get_tools_search_paths(false);
483 if let Some(path) = env::var_os("PATH") {
484 new_path.extend(env::split_paths(&path));
486 let new_path = env::join_paths(new_path).unwrap();
487 cmd.env("PATH", new_path);
490 match sess.time("run_dwp", || cmd.output()) {
491 Ok(prog) if !prog.status.success() => {
492 sess.struct_err(&format!(
493 "linking dwarf objects with `{}` failed: {}",
494 LLVM_DWP_EXECUTABLE, prog.status
496 .note(&format!("{:?}", &cmd))
497 .note(&escape_stdout_stderr_string(&prog.stdout))
498 .note(&escape_stdout_stderr_string(&prog.stderr))
500 info!("linker stderr:\n{}", escape_stdout_stderr_string(&prog.stderr));
501 info!("linker stdout:\n{}", escape_stdout_stderr_string(&prog.stdout));
505 let dwp_not_found = e.kind() == io::ErrorKind::NotFound;
506 let mut err = if dwp_not_found {
507 sess.struct_err(&format!("linker `{}` not found", LLVM_DWP_EXECUTABLE))
509 sess.struct_err(&format!("could not exec the linker `{}`", LLVM_DWP_EXECUTABLE))
512 err.note(&e.to_string());
515 err.note(&format!("{:?}", &cmd));
523 /// Create a dynamic library or executable.
525 /// This will invoke the system linker/cc to create the resulting file. This links to all upstream
527 fn link_natively<'a, B: ArchiveBuilder<'a>>(
529 crate_type: CrateType,
531 codegen_results: &CodegenResults,
534 info!("preparing {:?} to {:?}", crate_type, out_filename);
535 let (linker_path, flavor) = linker_and_flavor(sess);
536 let mut cmd = linker_with_args::<B>(
546 linker::disable_localization(&mut cmd);
548 for &(ref k, ref v) in &sess.target.link_env {
551 for k in &sess.target.link_env_remove {
555 if sess.opts.debugging_opts.print_link_args {
556 println!("{:?}", &cmd);
559 // May have not found libraries in the right formats.
560 sess.abort_if_errors();
562 // Invoke the system linker
564 let retry_on_segfault = env::var("RUSTC_RETRY_LINKER_ON_SEGFAULT").is_ok();
569 prog = sess.time("run_linker", || exec_linker(sess, &cmd, out_filename, tmpdir));
570 let output = match prog {
571 Ok(ref output) => output,
574 if output.status.success() {
577 let mut out = output.stderr.clone();
578 out.extend(&output.stdout);
579 let out = String::from_utf8_lossy(&out);
581 // Check to see if the link failed with "unrecognized command line option:
582 // '-no-pie'" for gcc or "unknown argument: '-no-pie'" for clang. If so,
583 // reperform the link step without the -no-pie option. This is safe because
584 // if the linker doesn't support -no-pie then it should not default to
585 // linking executables as pie. Different versions of gcc seem to use
586 // different quotes in the error message so don't check for them.
587 if sess.target.linker_is_gnu
588 && flavor != LinkerFlavor::Ld
589 && (out.contains("unrecognized command line option")
590 || out.contains("unknown argument"))
591 && out.contains("-no-pie")
592 && cmd.get_args().iter().any(|e| e.to_string_lossy() == "-no-pie")
594 info!("linker output: {:?}", out);
595 warn!("Linker does not support -no-pie command line option. Retrying without.");
596 for arg in cmd.take_args() {
597 if arg.to_string_lossy() != "-no-pie" {
605 // Detect '-static-pie' used with an older version of gcc or clang not supporting it.
606 // Fallback from '-static-pie' to '-static' in that case.
607 if sess.target.linker_is_gnu
608 && flavor != LinkerFlavor::Ld
609 && (out.contains("unrecognized command line option")
610 || out.contains("unknown argument"))
611 && (out.contains("-static-pie") || out.contains("--no-dynamic-linker"))
612 && cmd.get_args().iter().any(|e| e.to_string_lossy() == "-static-pie")
614 info!("linker output: {:?}", out);
616 "Linker does not support -static-pie command line option. Retrying with -static instead."
618 // Mirror `add_(pre,post)_link_objects` to replace CRT objects.
619 let self_contained = crt_objects_fallback(sess, crate_type);
620 let opts = &sess.target;
621 let pre_objects = if self_contained {
622 &opts.pre_link_objects_fallback
624 &opts.pre_link_objects
626 let post_objects = if self_contained {
627 &opts.post_link_objects_fallback
629 &opts.post_link_objects
631 let get_objects = |objects: &CrtObjects, kind| {
637 .map(|obj| get_object_file_path(sess, obj, self_contained).into_os_string())
640 let pre_objects_static_pie = get_objects(pre_objects, LinkOutputKind::StaticPicExe);
641 let post_objects_static_pie = get_objects(post_objects, LinkOutputKind::StaticPicExe);
642 let mut pre_objects_static = get_objects(pre_objects, LinkOutputKind::StaticNoPicExe);
643 let mut post_objects_static = get_objects(post_objects, LinkOutputKind::StaticNoPicExe);
644 // Assume that we know insertion positions for the replacement arguments from replaced
645 // arguments, which is true for all supported targets.
646 assert!(pre_objects_static.is_empty() || !pre_objects_static_pie.is_empty());
647 assert!(post_objects_static.is_empty() || !post_objects_static_pie.is_empty());
648 for arg in cmd.take_args() {
649 if arg.to_string_lossy() == "-static-pie" {
650 // Replace the output kind.
652 } else if pre_objects_static_pie.contains(&arg) {
653 // Replace the pre-link objects (replace the first and remove the rest).
654 cmd.args(mem::take(&mut pre_objects_static));
655 } else if post_objects_static_pie.contains(&arg) {
656 // Replace the post-link objects (replace the first and remove the rest).
657 cmd.args(mem::take(&mut post_objects_static));
666 // Here's a terribly awful hack that really shouldn't be present in any
667 // compiler. Here an environment variable is supported to automatically
668 // retry the linker invocation if the linker looks like it segfaulted.
670 // Gee that seems odd, normally segfaults are things we want to know
671 // about! Unfortunately though in rust-lang/rust#38878 we're
672 // experiencing the linker segfaulting on Travis quite a bit which is
673 // causing quite a bit of pain to land PRs when they spuriously fail
674 // due to a segfault.
676 // The issue #38878 has some more debugging information on it as well,
677 // but this unfortunately looks like it's just a race condition in
678 // macOS's linker with some thread pool working in the background. It
679 // seems that no one currently knows a fix for this so in the meantime
680 // we're left with this...
681 if !retry_on_segfault || i > 3 {
684 let msg_segv = "clang: error: unable to execute command: Segmentation fault: 11";
685 let msg_bus = "clang: error: unable to execute command: Bus error: 10";
686 if out.contains(msg_segv) || out.contains(msg_bus) {
688 "looks like the linker segfaulted when we tried to call it, \
689 automatically retrying again. cmd = {:?}, out = {}.",
695 if is_illegal_instruction(&output.status) {
697 "looks like the linker hit an illegal instruction when we \
698 tried to call it, automatically retrying again. cmd = {:?}, ]\
699 out = {}, status = {}.",
700 cmd, out, output.status,
706 fn is_illegal_instruction(status: &ExitStatus) -> bool {
707 use std::os::unix::prelude::*;
708 status.signal() == Some(libc::SIGILL)
712 fn is_illegal_instruction(_status: &ExitStatus) -> bool {
717 fn escape_string(s: &[u8]) -> String {
718 str::from_utf8(s).map(|s| s.to_owned()).unwrap_or_else(|_| {
719 let mut x = "Non-UTF-8 output: ".to_string();
720 x.extend(s.iter().flat_map(|&b| ascii::escape_default(b)).map(char::from));
727 if !prog.status.success() {
728 let mut output = prog.stderr.clone();
729 output.extend_from_slice(&prog.stdout);
730 sess.struct_err(&format!(
731 "linking with `{}` failed: {}",
732 linker_path.display(),
735 .note(&format!("{:?}", &cmd))
736 .note(&escape_stdout_stderr_string(&output))
739 // If MSVC's `link.exe` was expected but the return code
740 // is not a Microsoft LNK error then suggest a way to fix or
741 // install the Visual Studio build tools.
742 if let Some(code) = prog.status.code() {
743 if sess.target.is_like_msvc
744 && flavor == LinkerFlavor::Msvc
745 // Respect the command line override
746 && sess.opts.cg.linker.is_none()
747 // Match exactly "link.exe"
748 && linker_path.to_str() == Some("link.exe")
749 // All Microsoft `link.exe` linking error codes are
750 // four digit numbers in the range 1000 to 9999 inclusive
751 && (code < 1000 || code > 9999)
753 let is_vs_installed = windows_registry::find_vs_version().is_ok();
754 let has_linker = windows_registry::find_tool(
755 &sess.opts.target_triple.triple(),
760 sess.note_without_error("`link.exe` returned an unexpected error");
761 if is_vs_installed && has_linker {
762 // the linker is broken
763 sess.note_without_error(
764 "the Visual Studio build tools may need to be repaired \
765 using the Visual Studio installer",
767 sess.note_without_error(
768 "or a necessary component may be missing from the \
769 \"C++ build tools\" workload",
771 } else if is_vs_installed {
772 // the linker is not installed
773 sess.note_without_error(
774 "in the Visual Studio installer, ensure the \
775 \"C++ build tools\" workload is selected",
778 // visual studio is not installed
779 sess.note_without_error(
780 "you may need to install Visual Studio build tools with the \
781 \"C++ build tools\" workload",
787 sess.abort_if_errors();
789 info!("linker stderr:\n{}", escape_stdout_stderr_string(&prog.stderr));
790 info!("linker stdout:\n{}", escape_stdout_stderr_string(&prog.stdout));
793 let linker_not_found = e.kind() == io::ErrorKind::NotFound;
795 let mut linker_error = {
796 if linker_not_found {
797 sess.struct_err(&format!("linker `{}` not found", linker_path.display()))
799 sess.struct_err(&format!(
800 "could not exec the linker `{}`",
801 linker_path.display()
806 linker_error.note(&e.to_string());
808 if !linker_not_found {
809 linker_error.note(&format!("{:?}", &cmd));
814 if sess.target.is_like_msvc && linker_not_found {
815 sess.note_without_error(
816 "the msvc targets depend on the msvc linker \
817 but `link.exe` was not found",
819 sess.note_without_error(
820 "please ensure that VS 2013, VS 2015, VS 2017 or VS 2019 \
821 was installed with the Visual C++ option",
824 sess.abort_if_errors();
828 match sess.split_debuginfo() {
829 // If split debug information is disabled or located in individual files
830 // there's nothing to do here.
831 SplitDebuginfo::Off | SplitDebuginfo::Unpacked => {}
833 // If packed split-debuginfo is requested, but the final compilation
834 // doesn't actually have any debug information, then we skip this step.
835 SplitDebuginfo::Packed if sess.opts.debuginfo == DebugInfo::None => {}
837 // On macOS the external `dsymutil` tool is used to create the packed
838 // debug information. Note that this will read debug information from
839 // the objects on the filesystem which we'll clean up later.
840 SplitDebuginfo::Packed if sess.target.is_like_osx => {
841 let prog = Command::new("dsymutil").arg(out_filename).output();
844 if !prog.status.success() {
845 let mut output = prog.stderr.clone();
846 output.extend_from_slice(&prog.stdout);
847 sess.struct_warn(&format!(
848 "processing debug info with `dsymutil` failed: {}",
851 .note(&escape_string(&output))
855 Err(e) => sess.fatal(&format!("unable to run `dsymutil`: {}", e)),
859 // On MSVC packed debug information is produced by the linker itself so
860 // there's no need to do anything else here.
861 SplitDebuginfo::Packed if sess.target.is_like_msvc => {}
863 // ... and otherwise we're processing a `*.dwp` packed dwarf file.
864 SplitDebuginfo::Packed => link_dwarf_object(sess, &out_filename),
868 fn link_sanitizers(sess: &Session, crate_type: CrateType, linker: &mut dyn Linker) {
869 // On macOS the runtimes are distributed as dylibs which should be linked to
870 // both executables and dynamic shared objects. Everywhere else the runtimes
871 // are currently distributed as static liraries which should be linked to
873 let needs_runtime = match crate_type {
874 CrateType::Executable => true,
875 CrateType::Dylib | CrateType::Cdylib | CrateType::ProcMacro => sess.target.is_like_osx,
876 CrateType::Rlib | CrateType::Staticlib => false,
883 let sanitizer = sess.opts.debugging_opts.sanitizer;
884 if sanitizer.contains(SanitizerSet::ADDRESS) {
885 link_sanitizer_runtime(sess, linker, "asan");
887 if sanitizer.contains(SanitizerSet::LEAK) {
888 link_sanitizer_runtime(sess, linker, "lsan");
890 if sanitizer.contains(SanitizerSet::MEMORY) {
891 link_sanitizer_runtime(sess, linker, "msan");
893 if sanitizer.contains(SanitizerSet::THREAD) {
894 link_sanitizer_runtime(sess, linker, "tsan");
896 if sanitizer.contains(SanitizerSet::HWADDRESS) {
897 link_sanitizer_runtime(sess, linker, "hwasan");
901 fn link_sanitizer_runtime(sess: &Session, linker: &mut dyn Linker, name: &str) {
902 fn find_sanitizer_runtime(sess: &Session, filename: &String) -> PathBuf {
904 filesearch::make_target_lib_path(&sess.sysroot, sess.opts.target_triple.triple());
905 let path = session_tlib.join(&filename);
909 let default_sysroot = filesearch::get_or_default_sysroot();
910 let default_tlib = filesearch::make_target_lib_path(
912 sess.opts.target_triple.triple(),
918 let channel = option_env!("CFG_RELEASE_CHANNEL")
919 .map(|channel| format!("-{}", channel))
920 .unwrap_or_default();
922 if sess.target.is_like_osx {
923 // On Apple platforms, the sanitizer is always built as a dylib, and
924 // LLVM will link to `@rpath/*.dylib`, so we need to specify an
925 // rpath to the library as well (the rpath should be absolute, see
926 // PR #41352 for details).
927 let filename = format!("rustc{}_rt.{}", channel, name);
928 let path = find_sanitizer_runtime(&sess, &filename);
929 let rpath = path.to_str().expect("non-utf8 component in path");
930 linker.args(&["-Wl,-rpath", "-Xlinker", rpath]);
931 linker.link_dylib(Symbol::intern(&filename), false, true);
933 let filename = format!("librustc{}_rt.{}.a", channel, name);
934 let path = find_sanitizer_runtime(&sess, &filename).join(&filename);
935 linker.link_whole_rlib(&path);
939 /// Returns a boolean indicating whether the specified crate should be ignored
942 /// Crates ignored during LTO are not lumped together in the "massive object
943 /// file" that we create and are linked in their normal rlib states. See
944 /// comments below for what crates do not participate in LTO.
946 /// It's unusual for a crate to not participate in LTO. Typically only
947 /// compiler-specific and unstable crates have a reason to not participate in
949 pub fn ignored_for_lto(sess: &Session, info: &CrateInfo, cnum: CrateNum) -> bool {
950 // If our target enables builtin function lowering in LLVM then the
951 // crates providing these functions don't participate in LTO (e.g.
952 // no_builtins or compiler builtins crates).
953 !sess.target.no_builtins
954 && (info.compiler_builtins == Some(cnum) || info.is_no_builtins.contains(&cnum))
957 fn linker_and_flavor(sess: &Session) -> (PathBuf, LinkerFlavor) {
960 linker: Option<PathBuf>,
961 flavor: Option<LinkerFlavor>,
962 ) -> Option<(PathBuf, LinkerFlavor)> {
963 match (linker, flavor) {
964 (Some(linker), Some(flavor)) => Some((linker, flavor)),
965 // only the linker flavor is known; use the default linker for the selected flavor
966 (None, Some(flavor)) => Some((
967 PathBuf::from(match flavor {
968 LinkerFlavor::Em => {
975 LinkerFlavor::Gcc => {
976 if cfg!(any(target_os = "solaris", target_os = "illumos")) {
977 // On historical Solaris systems, "cc" may have
978 // been Sun Studio, which is not flag-compatible
979 // with "gcc". This history casts a long shadow,
980 // and many modern illumos distributions today
981 // ship GCC as "gcc" without also making it
982 // available as "cc".
988 LinkerFlavor::Ld => "ld",
989 LinkerFlavor::Msvc => "link.exe",
990 LinkerFlavor::Lld(_) => "lld",
991 LinkerFlavor::PtxLinker => "rust-ptx-linker",
995 (Some(linker), None) => {
996 let stem = linker.file_stem().and_then(|stem| stem.to_str()).unwrap_or_else(|| {
997 sess.fatal("couldn't extract file stem from specified linker")
1000 let flavor = if stem == "emcc" {
1002 } else if stem == "gcc"
1003 || stem.ends_with("-gcc")
1005 || stem.ends_with("-clang")
1008 } else if stem == "ld" || stem == "ld.lld" || stem.ends_with("-ld") {
1010 } else if stem == "link" || stem == "lld-link" {
1012 } else if stem == "lld" || stem == "rust-lld" {
1013 LinkerFlavor::Lld(sess.target.lld_flavor)
1015 // fall back to the value in the target spec
1016 sess.target.linker_flavor
1019 Some((linker, flavor))
1021 (None, None) => None,
1025 // linker and linker flavor specified via command line have precedence over what the target
1026 // specification specifies
1027 if let Some(ret) = infer_from(sess, sess.opts.cg.linker.clone(), sess.opts.cg.linker_flavor) {
1031 if let Some(ret) = infer_from(
1033 sess.target.linker.clone().map(PathBuf::from),
1034 Some(sess.target.linker_flavor),
1039 bug!("Not enough information provided to determine how to invoke the linker");
1042 /// Returns a boolean indicating whether we should preserve the object files on
1043 /// the filesystem for their debug information. This is often useful with
1044 /// split-dwarf like schemes.
1045 fn preserve_objects_for_their_debuginfo(sess: &Session) -> bool {
1046 // If the objects don't have debuginfo there's nothing to preserve.
1047 if sess.opts.debuginfo == config::DebugInfo::None {
1051 // If we're only producing artifacts that are archives, no need to preserve
1052 // the objects as they're losslessly contained inside the archives.
1054 sess.crate_types().iter().any(|&x| x != CrateType::Rlib && x != CrateType::Staticlib);
1059 // "unpacked" split debuginfo means that we leave object files as the
1060 // debuginfo is found in the original object files themselves
1061 sess.split_debuginfo() == SplitDebuginfo::Unpacked
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::Static { bundle: Some(false), .. }
1081 | NativeLibKind::Dylib { .. }
1082 | NativeLibKind::Unspecified => {
1083 let verbatim = lib.verbatim.unwrap_or(false);
1084 if sess.target.is_like_msvc {
1085 Some(format!("{}{}", name, if verbatim { "" } else { ".lib" }))
1086 } else if sess.target.linker_is_gnu {
1087 Some(format!("-l{}{}", if verbatim { ":" } else { "" }, name))
1089 Some(format!("-l{}", name))
1092 NativeLibKind::Framework { .. } => {
1093 // ld-only syntax, since there are no frameworks in MSVC
1094 Some(format!("-framework {}", name))
1096 // These are included, no need to print them
1097 NativeLibKind::Static { bundle: None | Some(true), .. }
1098 | NativeLibKind::RawDylib => None,
1102 if !lib_args.is_empty() {
1103 sess.note_without_error(
1104 "Link against the following native artifacts when linking \
1105 against this static library. The order and any duplication \
1106 can be significant on some platforms.",
1108 // Prefix for greppability
1109 sess.note_without_error(&format!("native-static-libs: {}", &lib_args.join(" ")));
1113 fn get_object_file_path(sess: &Session, name: &str, self_contained: bool) -> PathBuf {
1114 let fs = sess.target_filesearch(PathKind::Native);
1115 let file_path = fs.get_lib_path().join(name);
1116 if file_path.exists() {
1119 // Special directory with objects used only in self-contained linkage mode
1121 let file_path = fs.get_self_contained_lib_path().join(name);
1122 if file_path.exists() {
1126 for search_path in fs.search_paths() {
1127 let file_path = search_path.dir.join(name);
1128 if file_path.exists() {
1138 out_filename: &Path,
1140 ) -> io::Result<Output> {
1141 // When attempting to spawn the linker we run a risk of blowing out the
1142 // size limits for spawning a new process with respect to the arguments
1143 // we pass on the command line.
1145 // Here we attempt to handle errors from the OS saying "your list of
1146 // arguments is too big" by reinvoking the linker again with an `@`-file
1147 // that contains all the arguments. The theory is that this is then
1148 // accepted on all linkers and the linker will read all its options out of
1149 // there instead of looking at the command line.
1150 if !cmd.very_likely_to_exceed_some_spawn_limit() {
1151 match cmd.command().stdout(Stdio::piped()).stderr(Stdio::piped()).spawn() {
1153 let output = child.wait_with_output();
1154 flush_linked_file(&output, out_filename)?;
1157 Err(ref e) if command_line_too_big(e) => {
1158 info!("command line to linker was too big: {}", e);
1160 Err(e) => return Err(e),
1164 info!("falling back to passing arguments to linker via an @-file");
1165 let mut cmd2 = cmd.clone();
1166 let mut args = String::new();
1167 for arg in cmd2.take_args() {
1169 &Escape { arg: arg.to_str().unwrap(), is_like_msvc: sess.target.is_like_msvc }
1174 let file = tmpdir.join("linker-arguments");
1175 let bytes = if sess.target.is_like_msvc {
1176 let mut out = Vec::with_capacity((1 + args.len()) * 2);
1177 // start the stream with a UTF-16 BOM
1178 for c in std::iter::once(0xFEFF).chain(args.encode_utf16()) {
1179 // encode in little endian
1181 out.push((c >> 8) as u8);
1187 fs::write(&file, &bytes)?;
1188 cmd2.arg(format!("@{}", file.display()));
1189 info!("invoking linker {:?}", cmd2);
1190 let output = cmd2.output();
1191 flush_linked_file(&output, out_filename)?;
1194 #[cfg(not(windows))]
1195 fn flush_linked_file(_: &io::Result<Output>, _: &Path) -> io::Result<()> {
1200 fn flush_linked_file(
1201 command_output: &io::Result<Output>,
1202 out_filename: &Path,
1203 ) -> io::Result<()> {
1204 // On Windows, under high I/O load, output buffers are sometimes not flushed,
1205 // even long after process exit, causing nasty, non-reproducible output bugs.
1207 // File::sync_all() calls FlushFileBuffers() down the line, which solves the problem.
1209 // А full writeup of the original Chrome bug can be found at
1210 // randomascii.wordpress.com/2018/02/25/compiler-bug-linker-bug-windows-kernel-bug/amp
1212 if let &Ok(ref out) = command_output {
1213 if out.status.success() {
1214 if let Ok(of) = fs::OpenOptions::new().write(true).open(out_filename) {
1224 fn command_line_too_big(err: &io::Error) -> bool {
1225 err.raw_os_error() == Some(::libc::E2BIG)
1229 fn command_line_too_big(err: &io::Error) -> bool {
1230 const ERROR_FILENAME_EXCED_RANGE: i32 = 206;
1231 err.raw_os_error() == Some(ERROR_FILENAME_EXCED_RANGE)
1234 #[cfg(not(any(unix, windows)))]
1235 fn command_line_too_big(_: &io::Error) -> bool {
1244 impl<'a> fmt::Display for Escape<'a> {
1245 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1246 if self.is_like_msvc {
1247 // This is "documented" at
1248 // https://docs.microsoft.com/en-us/cpp/build/reference/at-specify-a-linker-response-file
1250 // Unfortunately there's not a great specification of the
1251 // syntax I could find online (at least) but some local
1252 // testing showed that this seemed sufficient-ish to catch
1253 // at least a few edge cases.
1255 for c in self.arg.chars() {
1257 '"' => write!(f, "\\{}", c)?,
1258 c => write!(f, "{}", c)?,
1263 // This is documented at https://linux.die.net/man/1/ld, namely:
1265 // > Options in file are separated by whitespace. A whitespace
1266 // > character may be included in an option by surrounding the
1267 // > entire option in either single or double quotes. Any
1268 // > character (including a backslash) may be included by
1269 // > prefixing the character to be included with a backslash.
1271 // We put an argument on each line, so all we need to do is
1272 // ensure the line is interpreted as one whole argument.
1273 for c in self.arg.chars() {
1275 '\\' | ' ' => write!(f, "\\{}", c)?,
1276 c => write!(f, "{}", c)?,
1285 fn link_output_kind(sess: &Session, crate_type: CrateType) -> LinkOutputKind {
1286 let kind = match (crate_type, sess.crt_static(Some(crate_type)), sess.relocation_model()) {
1287 (CrateType::Executable, _, _) if sess.is_wasi_reactor() => LinkOutputKind::WasiReactorExe,
1288 (CrateType::Executable, false, RelocModel::Pic) => LinkOutputKind::DynamicPicExe,
1289 (CrateType::Executable, false, _) => LinkOutputKind::DynamicNoPicExe,
1290 (CrateType::Executable, true, RelocModel::Pic) => LinkOutputKind::StaticPicExe,
1291 (CrateType::Executable, true, _) => LinkOutputKind::StaticNoPicExe,
1292 (_, true, _) => LinkOutputKind::StaticDylib,
1293 (_, false, _) => LinkOutputKind::DynamicDylib,
1296 // Adjust the output kind to target capabilities.
1297 let opts = &sess.target;
1298 let pic_exe_supported = opts.position_independent_executables;
1299 let static_pic_exe_supported = opts.static_position_independent_executables;
1300 let static_dylib_supported = opts.crt_static_allows_dylibs;
1302 LinkOutputKind::DynamicPicExe if !pic_exe_supported => LinkOutputKind::DynamicNoPicExe,
1303 LinkOutputKind::StaticPicExe if !static_pic_exe_supported => LinkOutputKind::StaticNoPicExe,
1304 LinkOutputKind::StaticDylib if !static_dylib_supported => LinkOutputKind::DynamicDylib,
1309 // Returns true if linker is located within sysroot
1310 fn detect_self_contained_mingw(sess: &Session) -> bool {
1311 let (linker, _) = linker_and_flavor(&sess);
1312 // Assume `-C linker=rust-lld` as self-contained mode
1313 if linker == Path::new("rust-lld") {
1316 let linker_with_extension = if cfg!(windows) && linker.extension().is_none() {
1317 linker.with_extension("exe")
1321 for dir in env::split_paths(&env::var_os("PATH").unwrap_or_default()) {
1322 let full_path = dir.join(&linker_with_extension);
1323 // If linker comes from sysroot assume self-contained mode
1324 if full_path.is_file() && !full_path.starts_with(&sess.sysroot) {
1331 /// Whether we link to our own CRT objects instead of relying on gcc to pull them.
1332 /// We only provide such support for a very limited number of targets.
1333 fn crt_objects_fallback(sess: &Session, crate_type: CrateType) -> bool {
1334 if let Some(self_contained) = sess.opts.cg.link_self_contained {
1335 return self_contained;
1338 match sess.target.crt_objects_fallback {
1339 // FIXME: Find a better heuristic for "native musl toolchain is available",
1340 // based on host and linker path, for example.
1341 // (https://github.com/rust-lang/rust/pull/71769#issuecomment-626330237).
1342 Some(CrtObjectsFallback::Musl) => sess.crt_static(Some(crate_type)),
1343 Some(CrtObjectsFallback::Mingw) => {
1344 sess.host == sess.target
1345 && sess.target.vendor != "uwp"
1346 && detect_self_contained_mingw(&sess)
1348 // FIXME: Figure out cases in which WASM needs to link with a native toolchain.
1349 Some(CrtObjectsFallback::Wasm) => true,
1354 /// Add pre-link object files defined by the target spec.
1355 fn add_pre_link_objects(
1356 cmd: &mut dyn Linker,
1358 link_output_kind: LinkOutputKind,
1359 self_contained: bool,
1361 let opts = &sess.target;
1363 if self_contained { &opts.pre_link_objects_fallback } else { &opts.pre_link_objects };
1364 for obj in objects.get(&link_output_kind).iter().copied().flatten() {
1365 cmd.add_object(&get_object_file_path(sess, obj, self_contained));
1369 /// Add post-link object files defined by the target spec.
1370 fn add_post_link_objects(
1371 cmd: &mut dyn Linker,
1373 link_output_kind: LinkOutputKind,
1374 self_contained: bool,
1376 let opts = &sess.target;
1378 if self_contained { &opts.post_link_objects_fallback } else { &opts.post_link_objects };
1379 for obj in objects.get(&link_output_kind).iter().copied().flatten() {
1380 cmd.add_object(&get_object_file_path(sess, obj, self_contained));
1384 /// Add arbitrary "pre-link" args defined by the target spec or from command line.
1385 /// FIXME: Determine where exactly these args need to be inserted.
1386 fn add_pre_link_args(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavor) {
1387 if let Some(args) = sess.target.pre_link_args.get(&flavor) {
1390 cmd.args(&sess.opts.debugging_opts.pre_link_args);
1393 /// Add a link script embedded in the target, if applicable.
1394 fn add_link_script(cmd: &mut dyn Linker, sess: &Session, tmpdir: &Path, crate_type: CrateType) {
1395 match (crate_type, &sess.target.link_script) {
1396 (CrateType::Cdylib | CrateType::Executable, Some(script)) => {
1397 if !sess.target.linker_is_gnu {
1398 sess.fatal("can only use link script when linking with GNU-like linker");
1401 let file_name = ["rustc", &sess.target.llvm_target, "linkfile.ld"].join("-");
1403 let path = tmpdir.join(file_name);
1404 if let Err(e) = fs::write(&path, script) {
1405 sess.fatal(&format!("failed to write link script to {}: {}", path.display(), e));
1408 cmd.arg("--script");
1415 /// Add arbitrary "user defined" args defined from command line.
1416 /// FIXME: Determine where exactly these args need to be inserted.
1417 fn add_user_defined_link_args(cmd: &mut dyn Linker, sess: &Session) {
1418 cmd.args(&sess.opts.cg.link_args);
1421 /// Add arbitrary "late link" args defined by the target spec.
1422 /// FIXME: Determine where exactly these args need to be inserted.
1423 fn add_late_link_args(
1424 cmd: &mut dyn Linker,
1426 flavor: LinkerFlavor,
1427 crate_type: CrateType,
1428 codegen_results: &CodegenResults,
1430 let any_dynamic_crate = crate_type == CrateType::Dylib
1431 || codegen_results.crate_info.dependency_formats.iter().any(|(ty, list)| {
1432 *ty == crate_type && list.iter().any(|&linkage| linkage == Linkage::Dynamic)
1434 if any_dynamic_crate {
1435 if let Some(args) = sess.target.late_link_args_dynamic.get(&flavor) {
1439 if let Some(args) = sess.target.late_link_args_static.get(&flavor) {
1443 if let Some(args) = sess.target.late_link_args.get(&flavor) {
1448 /// Add arbitrary "post-link" args defined by the target spec.
1449 /// FIXME: Determine where exactly these args need to be inserted.
1450 fn add_post_link_args(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavor) {
1451 if let Some(args) = sess.target.post_link_args.get(&flavor) {
1456 /// Add object files containing code from the current crate.
1457 fn add_local_crate_regular_objects(cmd: &mut dyn Linker, codegen_results: &CodegenResults) {
1458 for obj in codegen_results.modules.iter().filter_map(|m| m.object.as_ref()) {
1459 cmd.add_object(obj);
1463 /// Add object files for allocator code linked once for the whole crate tree.
1464 fn add_local_crate_allocator_objects(cmd: &mut dyn Linker, codegen_results: &CodegenResults) {
1465 if let Some(obj) = codegen_results.allocator_module.as_ref().and_then(|m| m.object.as_ref()) {
1466 cmd.add_object(obj);
1470 /// Add object files containing metadata for the current crate.
1471 fn add_local_crate_metadata_objects(
1472 cmd: &mut dyn Linker,
1473 crate_type: CrateType,
1474 codegen_results: &CodegenResults,
1476 // When linking a dynamic library, we put the metadata into a section of the
1477 // executable. This metadata is in a separate object file from the main
1478 // object file, so we link that in here.
1479 if crate_type == CrateType::Dylib || crate_type == CrateType::ProcMacro {
1480 if let Some(obj) = codegen_results.metadata_module.as_ref().and_then(|m| m.object.as_ref())
1482 cmd.add_object(obj);
1487 /// Link native libraries corresponding to the current crate and all libraries corresponding to
1488 /// all its dependency crates.
1489 /// FIXME: Consider combining this with the functions above adding object files for the local crate.
1490 fn link_local_crate_native_libs_and_dependent_crate_libs<'a, B: ArchiveBuilder<'a>>(
1491 cmd: &mut dyn Linker,
1493 crate_type: CrateType,
1494 codegen_results: &CodegenResults,
1497 // Take careful note of the ordering of the arguments we pass to the linker
1498 // here. Linkers will assume that things on the left depend on things to the
1499 // right. Things on the right cannot depend on things on the left. This is
1500 // all formally implemented in terms of resolving symbols (libs on the right
1501 // resolve unknown symbols of libs on the left, but not vice versa).
1503 // For this reason, we have organized the arguments we pass to the linker as
1506 // 1. The local object that LLVM just generated
1507 // 2. Local native libraries
1508 // 3. Upstream rust libraries
1509 // 4. Upstream native libraries
1511 // The rationale behind this ordering is that those items lower down in the
1512 // list can't depend on items higher up in the list. For example nothing can
1513 // depend on what we just generated (e.g., that'd be a circular dependency).
1514 // Upstream rust libraries are not allowed to depend on our local native
1515 // libraries as that would violate the structure of the DAG, in that
1516 // scenario they are required to link to them as well in a shared fashion.
1518 // Note that upstream rust libraries may contain native dependencies as
1519 // well, but they also can't depend on what we just started to add to the
1520 // link line. And finally upstream native libraries can't depend on anything
1521 // in this DAG so far because they're only dylibs and dylibs can only depend
1522 // on other dylibs (e.g., other native deps).
1524 // If -Zlink-native-libraries=false is set, then the assumption is that an
1525 // external build system already has the native dependencies defined, and it
1526 // will provide them to the linker itself.
1527 if sess.opts.debugging_opts.link_native_libraries {
1528 add_local_native_libraries(cmd, sess, codegen_results);
1530 add_upstream_rust_crates::<B>(cmd, sess, codegen_results, crate_type, tmpdir);
1531 if sess.opts.debugging_opts.link_native_libraries {
1532 add_upstream_native_libraries(cmd, sess, codegen_results, crate_type);
1536 /// Add sysroot and other globally set directories to the directory search list.
1537 fn add_library_search_dirs(cmd: &mut dyn Linker, sess: &Session, self_contained: bool) {
1538 // The default library location, we need this to find the runtime.
1539 // The location of crates will be determined as needed.
1540 let lib_path = sess.target_filesearch(PathKind::All).get_lib_path();
1541 cmd.include_path(&fix_windows_verbatim_for_gcc(&lib_path));
1543 // Special directory with libraries used only in self-contained linkage mode
1545 let lib_path = sess.target_filesearch(PathKind::All).get_self_contained_lib_path();
1546 cmd.include_path(&fix_windows_verbatim_for_gcc(&lib_path));
1550 /// Add options making relocation sections in the produced ELF files read-only
1551 /// and suppressing lazy binding.
1552 fn add_relro_args(cmd: &mut dyn Linker, sess: &Session) {
1553 match sess.opts.debugging_opts.relro_level.unwrap_or(sess.target.relro_level) {
1554 RelroLevel::Full => cmd.full_relro(),
1555 RelroLevel::Partial => cmd.partial_relro(),
1556 RelroLevel::Off => cmd.no_relro(),
1557 RelroLevel::None => {}
1561 /// Add library search paths used at runtime by dynamic linkers.
1563 cmd: &mut dyn Linker,
1565 codegen_results: &CodegenResults,
1566 out_filename: &Path,
1568 // FIXME (#2397): At some point we want to rpath our guesses as to
1569 // where extern libraries might live, based on the
1570 // addl_lib_search_paths
1571 if sess.opts.cg.rpath {
1572 let target_triple = sess.opts.target_triple.triple();
1573 let mut get_install_prefix_lib_path = || {
1574 let install_prefix = option_env!("CFG_PREFIX").expect("CFG_PREFIX");
1575 let tlib = rustc_target::target_rustlib_path(&sess.sysroot, target_triple).join("lib");
1576 let mut path = PathBuf::from(install_prefix);
1581 let mut rpath_config = RPathConfig {
1582 used_crates: &codegen_results.crate_info.used_crates_dynamic,
1583 out_filename: out_filename.to_path_buf(),
1584 has_rpath: sess.target.has_rpath,
1585 is_like_osx: sess.target.is_like_osx,
1586 linker_is_gnu: sess.target.linker_is_gnu,
1587 get_install_prefix_lib_path: &mut get_install_prefix_lib_path,
1589 cmd.args(&rpath::get_rpath_flags(&mut rpath_config));
1593 /// Produce the linker command line containing linker path and arguments.
1594 /// `NO-OPT-OUT` marks the arguments that cannot be removed from the command line
1595 /// by the user without creating a custom target specification.
1596 /// `OBJECT-FILES` specify whether the arguments can add object files.
1597 /// `CUSTOMIZATION-POINT` means that arbitrary arguments defined by the user
1598 /// or by the target spec can be inserted here.
1599 /// `AUDIT-ORDER` - need to figure out whether the option is order-dependent or not.
1600 fn linker_with_args<'a, B: ArchiveBuilder<'a>>(
1602 flavor: LinkerFlavor,
1604 crate_type: CrateType,
1606 out_filename: &Path,
1607 codegen_results: &CodegenResults,
1609 let crt_objects_fallback = crt_objects_fallback(sess, crate_type);
1610 let base_cmd = get_linker(sess, path, flavor, crt_objects_fallback);
1611 // FIXME: Move `/LIBPATH` addition for uwp targets from the linker construction
1612 // to the linker args construction.
1613 assert!(base_cmd.get_args().is_empty() || sess.target.vendor == "uwp");
1614 let cmd = &mut *codegen_results.linker_info.to_linker(base_cmd, &sess, flavor);
1615 let link_output_kind = link_output_kind(sess, crate_type);
1617 // NO-OPT-OUT, OBJECT-FILES-MAYBE, CUSTOMIZATION-POINT
1618 add_pre_link_args(cmd, sess, flavor);
1620 // NO-OPT-OUT, OBJECT-FILES-NO
1621 add_apple_sdk(cmd, sess, flavor);
1624 add_link_script(cmd, sess, tmpdir, crate_type);
1626 // NO-OPT-OUT, OBJECT-FILES-NO, AUDIT-ORDER
1627 if sess.target.is_like_fuchsia && crate_type == CrateType::Executable {
1628 let prefix = if sess.opts.debugging_opts.sanitizer.contains(SanitizerSet::ADDRESS) {
1633 cmd.arg(format!("--dynamic-linker={}ld.so.1", prefix));
1636 // NO-OPT-OUT, OBJECT-FILES-NO, AUDIT-ORDER
1637 if sess.target.eh_frame_header {
1638 cmd.add_eh_frame_header();
1641 // NO-OPT-OUT, OBJECT-FILES-NO, AUDIT-ORDER
1642 // Make the binary compatible with data execution prevention schemes.
1645 // NO-OPT-OUT, OBJECT-FILES-NO
1646 // Avoid linking to dynamic libraries unless they satisfy some undefined symbols
1647 // at the point at which they are specified on the command line.
1648 // Must be passed before any dynamic libraries.
1649 cmd.add_as_needed();
1651 // NO-OPT-OUT, OBJECT-FILES-NO
1652 if crt_objects_fallback {
1653 cmd.no_crt_objects();
1656 // NO-OPT-OUT, OBJECT-FILES-YES
1657 add_pre_link_objects(cmd, sess, link_output_kind, crt_objects_fallback);
1659 // NO-OPT-OUT, OBJECT-FILES-NO, AUDIT-ORDER
1660 if sess.target.is_like_emscripten {
1662 cmd.arg(if sess.panic_strategy() == PanicStrategy::Abort {
1663 "DISABLE_EXCEPTION_CATCHING=1"
1665 "DISABLE_EXCEPTION_CATCHING=0"
1669 // OBJECT-FILES-YES, AUDIT-ORDER
1670 link_sanitizers(sess, crate_type, cmd);
1672 // OBJECT-FILES-NO, AUDIT-ORDER
1673 // Linker plugins should be specified early in the list of arguments
1674 // FIXME: How "early" exactly?
1675 cmd.linker_plugin_lto();
1677 // NO-OPT-OUT, OBJECT-FILES-NO, AUDIT-ORDER
1678 // FIXME: Order-dependent, at least relatively to other args adding searh directories.
1679 add_library_search_dirs(cmd, sess, crt_objects_fallback);
1682 add_local_crate_regular_objects(cmd, codegen_results);
1684 // NO-OPT-OUT, OBJECT-FILES-NO, AUDIT-ORDER
1685 cmd.output_filename(out_filename);
1687 // OBJECT-FILES-NO, AUDIT-ORDER
1688 if crate_type == CrateType::Executable && sess.target.is_like_windows {
1689 if let Some(ref s) = codegen_results.windows_subsystem {
1694 // NO-OPT-OUT, OBJECT-FILES-NO, AUDIT-ORDER
1695 // If we're building something like a dynamic library then some platforms
1696 // need to make sure that all symbols are exported correctly from the
1698 cmd.export_symbols(tmpdir, crate_type);
1701 add_local_crate_metadata_objects(cmd, crate_type, codegen_results);
1704 add_local_crate_allocator_objects(cmd, codegen_results);
1706 // OBJECT-FILES-NO, AUDIT-ORDER
1707 // FIXME: Order dependent, applies to the following objects. Where should it be placed?
1708 // Try to strip as much out of the generated object by removing unused
1709 // sections if possible. See more comments in linker.rs
1710 if !sess.link_dead_code() {
1711 let keep_metadata = crate_type == CrateType::Dylib;
1712 cmd.gc_sections(keep_metadata);
1715 // NO-OPT-OUT, OBJECT-FILES-NO, AUDIT-ORDER
1716 cmd.set_output_kind(link_output_kind, out_filename);
1718 // OBJECT-FILES-NO, AUDIT-ORDER
1719 add_relro_args(cmd, sess);
1721 // OBJECT-FILES-NO, AUDIT-ORDER
1722 // Pass optimization flags down to the linker.
1725 // OBJECT-FILES-NO, AUDIT-ORDER
1726 // Pass debuginfo and strip flags down to the linker.
1727 cmd.debuginfo(sess.opts.debugging_opts.strip);
1729 // OBJECT-FILES-NO, AUDIT-ORDER
1730 // We want to prevent the compiler from accidentally leaking in any system libraries,
1731 // so by default we tell linkers not to link to any default libraries.
1732 if !sess.opts.cg.default_linker_libraries && sess.target.no_default_libraries {
1733 cmd.no_default_libraries();
1737 link_local_crate_native_libs_and_dependent_crate_libs::<B>(
1745 // OBJECT-FILES-NO, AUDIT-ORDER
1746 if sess.opts.cg.profile_generate.enabled() || sess.instrument_coverage() {
1750 // OBJECT-FILES-NO, AUDIT-ORDER
1751 if sess.opts.cg.control_flow_guard != CFGuard::Disabled {
1752 cmd.control_flow_guard();
1755 // OBJECT-FILES-NO, AUDIT-ORDER
1756 add_rpath_args(cmd, sess, codegen_results, out_filename);
1758 // OBJECT-FILES-MAYBE, CUSTOMIZATION-POINT
1759 add_user_defined_link_args(cmd, sess);
1761 // NO-OPT-OUT, OBJECT-FILES-NO, AUDIT-ORDER
1764 // NO-OPT-OUT, OBJECT-FILES-MAYBE, CUSTOMIZATION-POINT
1765 add_late_link_args(cmd, sess, flavor, crate_type, codegen_results);
1767 // NO-OPT-OUT, OBJECT-FILES-YES
1768 add_post_link_objects(cmd, sess, link_output_kind, crt_objects_fallback);
1770 // NO-OPT-OUT, OBJECT-FILES-MAYBE, CUSTOMIZATION-POINT
1771 add_post_link_args(cmd, sess, flavor);
1776 /// # Native library linking
1778 /// User-supplied library search paths (-L on the command line). These are the same paths used to
1779 /// find Rust crates, so some of them may have been added already by the previous crate linking
1780 /// code. This only allows them to be found at compile time so it is still entirely up to outside
1781 /// forces to make sure that library can be found at runtime.
1783 /// Also note that the native libraries linked here are only the ones located in the current crate.
1784 /// Upstream crates with native library dependencies may have their native library pulled in above.
1785 fn add_local_native_libraries(
1786 cmd: &mut dyn Linker,
1788 codegen_results: &CodegenResults,
1790 let filesearch = sess.target_filesearch(PathKind::All);
1791 for search_path in filesearch.search_paths() {
1792 match search_path.kind {
1793 PathKind::Framework => {
1794 cmd.framework_path(&search_path.dir);
1797 cmd.include_path(&fix_windows_verbatim_for_gcc(&search_path.dir));
1803 codegen_results.crate_info.used_libraries.iter().filter(|l| relevant_lib(sess, l));
1805 let search_path = archive_search_paths(sess);
1806 let mut last = (NativeLibKind::Unspecified, None);
1807 for lib in relevant_libs {
1808 // Skip if this library is the same as the last.
1809 last = if (lib.kind, lib.name) == last { continue } else { (lib.kind, lib.name) };
1811 let name = match lib.name {
1815 let verbatim = lib.verbatim.unwrap_or(false);
1817 NativeLibKind::Dylib { as_needed } => {
1818 cmd.link_dylib(name, verbatim, as_needed.unwrap_or(true))
1820 NativeLibKind::Unspecified => cmd.link_dylib(name, verbatim, true),
1821 NativeLibKind::Framework { as_needed } => {
1822 cmd.link_framework(name, as_needed.unwrap_or(true))
1824 NativeLibKind::Static { bundle: None | Some(true), .. }
1825 | NativeLibKind::Static { whole_archive: Some(true), .. } => {
1826 cmd.link_whole_staticlib(name, verbatim, &search_path);
1828 NativeLibKind::Static { .. } => cmd.link_staticlib(name, verbatim),
1829 NativeLibKind::RawDylib => {
1830 // FIXME(#58713): Proper handling for raw dylibs.
1831 bug!("raw_dylib feature not yet implemented");
1837 /// # Rust Crate linking
1839 /// Rust crates are not considered at all when creating an rlib output. All dependencies will be
1840 /// linked when producing the final output (instead of the intermediate rlib version).
1841 fn add_upstream_rust_crates<'a, B: ArchiveBuilder<'a>>(
1842 cmd: &mut dyn Linker,
1844 codegen_results: &CodegenResults,
1845 crate_type: CrateType,
1848 // All of the heavy lifting has previously been accomplished by the
1849 // dependency_format module of the compiler. This is just crawling the
1850 // output of that module, adding crates as necessary.
1852 // Linking to a rlib involves just passing it to the linker (the linker
1853 // will slurp up the object files inside), and linking to a dynamic library
1854 // involves just passing the right -l flag.
1856 let (_, data) = codegen_results
1860 .find(|(ty, _)| *ty == crate_type)
1861 .expect("failed to find crate type in dependency format list");
1863 // Invoke get_used_crates to ensure that we get a topological sorting of
1865 let deps = &codegen_results.crate_info.used_crates_dynamic;
1867 // There's a few internal crates in the standard library (aka libcore and
1868 // libstd) which actually have a circular dependence upon one another. This
1869 // currently arises through "weak lang items" where libcore requires things
1870 // like `rust_begin_unwind` but libstd ends up defining it. To get this
1871 // circular dependence to work correctly in all situations we'll need to be
1872 // sure to correctly apply the `--start-group` and `--end-group` options to
1873 // GNU linkers, otherwise if we don't use any other symbol from the standard
1874 // library it'll get discarded and the whole application won't link.
1876 // In this loop we're calculating the `group_end`, after which crate to
1877 // pass `--end-group` and `group_start`, before which crate to pass
1878 // `--start-group`. We currently do this by passing `--end-group` after
1879 // the first crate (when iterating backwards) that requires a lang item
1880 // defined somewhere else. Once that's set then when we've defined all the
1881 // necessary lang items we'll pass `--start-group`.
1883 // Note that this isn't amazing logic for now but it should do the trick
1884 // for the current implementation of the standard library.
1885 let mut group_end = None;
1886 let mut group_start = None;
1887 // Crates available for linking thus far.
1888 let mut available = FxHashSet::default();
1889 // Crates required to satisfy dependencies discovered so far.
1890 let mut required = FxHashSet::default();
1892 let info = &codegen_results.crate_info;
1893 for &(cnum, _) in deps.iter().rev() {
1894 if let Some(missing) = info.missing_lang_items.get(&cnum) {
1895 let missing_crates = missing.iter().map(|i| info.lang_item_to_crate.get(i).copied());
1896 required.extend(missing_crates);
1899 required.insert(Some(cnum));
1900 available.insert(Some(cnum));
1902 if required.len() > available.len() && group_end.is_none() {
1903 group_end = Some(cnum);
1905 if required.len() == available.len() && group_end.is_some() {
1906 group_start = Some(cnum);
1911 // If we didn't end up filling in all lang items from upstream crates then
1912 // we'll be filling it in with our crate. This probably means we're the
1913 // standard library itself, so skip this for now.
1914 if group_end.is_some() && group_start.is_none() {
1918 let mut compiler_builtins = None;
1920 for &(cnum, _) in deps.iter() {
1921 if group_start == Some(cnum) {
1925 // We may not pass all crates through to the linker. Some crates may
1926 // appear statically in an existing dylib, meaning we'll pick up all the
1927 // symbols from the dylib.
1928 let src = &codegen_results.crate_info.used_crate_source[&cnum];
1929 match data[cnum.as_usize() - 1] {
1930 _ if codegen_results.crate_info.profiler_runtime == Some(cnum) => {
1931 add_static_crate::<B>(cmd, sess, codegen_results, tmpdir, crate_type, cnum);
1933 // compiler-builtins are always placed last to ensure that they're
1934 // linked correctly.
1935 _ if codegen_results.crate_info.compiler_builtins == Some(cnum) => {
1936 assert!(compiler_builtins.is_none());
1937 compiler_builtins = Some(cnum);
1939 Linkage::NotLinked | Linkage::IncludedFromDylib => {}
1940 Linkage::Static => {
1941 add_static_crate::<B>(cmd, sess, codegen_results, tmpdir, crate_type, cnum);
1943 Linkage::Dynamic => add_dynamic_crate(cmd, sess, &src.dylib.as_ref().unwrap().0),
1946 if group_end == Some(cnum) {
1951 // compiler-builtins are always placed last to ensure that they're
1952 // linked correctly.
1953 // We must always link the `compiler_builtins` crate statically. Even if it
1954 // was already "included" in a dylib (e.g., `libstd` when `-C prefer-dynamic`
1956 if let Some(cnum) = compiler_builtins {
1957 add_static_crate::<B>(cmd, sess, codegen_results, tmpdir, crate_type, cnum);
1960 // Converts a library file-stem into a cc -l argument
1961 fn unlib<'a>(target: &Target, stem: &'a str) -> &'a str {
1962 if stem.starts_with("lib") && !target.is_like_windows { &stem[3..] } else { stem }
1965 // Adds the static "rlib" versions of all crates to the command line.
1966 // There's a bit of magic which happens here specifically related to LTO and
1967 // dynamic libraries. Specifically:
1969 // * For LTO, we remove upstream object files.
1970 // * For dylibs we remove metadata and bytecode from upstream rlibs
1972 // When performing LTO, almost(*) all of the bytecode from the upstream
1973 // libraries has already been included in our object file output. As a
1974 // result we need to remove the object files in the upstream libraries so
1975 // the linker doesn't try to include them twice (or whine about duplicate
1976 // symbols). We must continue to include the rest of the rlib, however, as
1977 // it may contain static native libraries which must be linked in.
1979 // (*) Crates marked with `#![no_builtins]` don't participate in LTO and
1980 // their bytecode wasn't included. The object files in those libraries must
1981 // still be passed to the linker.
1983 // When making a dynamic library, linkers by default don't include any
1984 // object files in an archive if they're not necessary to resolve the link.
1985 // We basically want to convert the archive (rlib) to a dylib, though, so we
1986 // *do* want everything included in the output, regardless of whether the
1987 // linker thinks it's needed or not. As a result we must use the
1988 // --whole-archive option (or the platform equivalent). When using this
1989 // option the linker will fail if there are non-objects in the archive (such
1990 // as our own metadata and/or bytecode). All in all, for rlibs to be
1991 // entirely included in dylibs, we need to remove all non-object files.
1993 // Note, however, that if we're not doing LTO or we're not producing a dylib
1994 // (aka we're making an executable), we can just pass the rlib blindly to
1995 // the linker (fast) because it's fine if it's not actually included as
1996 // we're at the end of the dependency chain.
1997 fn add_static_crate<'a, B: ArchiveBuilder<'a>>(
1998 cmd: &mut dyn Linker,
2000 codegen_results: &CodegenResults,
2002 crate_type: CrateType,
2005 let src = &codegen_results.crate_info.used_crate_source[&cnum];
2006 let cratepath = &src.rlib.as_ref().unwrap().0;
2008 // See the comment above in `link_staticlib` and `link_rlib` for why if
2009 // there's a static library that's not relevant we skip all object
2011 let native_libs = &codegen_results.crate_info.native_libraries[&cnum];
2012 let skip_native = native_libs.iter().any(|lib| {
2013 matches!(lib.kind, NativeLibKind::Static { bundle: None | Some(true), .. })
2014 && !relevant_lib(sess, lib)
2017 if (!are_upstream_rust_objects_already_included(sess)
2018 || ignored_for_lto(sess, &codegen_results.crate_info, cnum))
2019 && crate_type != CrateType::Dylib
2022 cmd.link_rlib(&fix_windows_verbatim_for_gcc(cratepath));
2026 let dst = tmpdir.join(cratepath.file_name().unwrap());
2027 let name = cratepath.file_name().unwrap().to_str().unwrap();
2028 let name = &name[3..name.len() - 5]; // chop off lib/.rlib
2030 sess.prof.generic_activity_with_arg("link_altering_rlib", name).run(|| {
2031 let mut archive = <B as ArchiveBuilder>::new(sess, &dst, Some(cratepath));
2032 archive.update_symbols();
2034 let mut any_objects = false;
2035 for f in archive.src_files() {
2036 if f == METADATA_FILENAME {
2037 archive.remove_file(&f);
2041 let canonical = f.replace("-", "_");
2042 let canonical_name = name.replace("-", "_");
2044 let is_rust_object =
2045 canonical.starts_with(&canonical_name) && looks_like_rust_object_file(&f);
2047 // If we've been requested to skip all native object files
2048 // (those not generated by the rust compiler) then we can skip
2049 // this file. See above for why we may want to do this.
2050 let skip_because_cfg_say_so = skip_native && !is_rust_object;
2052 // If we're performing LTO and this is a rust-generated object
2053 // file, then we don't need the object file as it's part of the
2054 // LTO module. Note that `#![no_builtins]` is excluded from LTO,
2055 // though, so we let that object file slide.
2056 let skip_because_lto = are_upstream_rust_objects_already_included(sess)
2058 && (sess.target.no_builtins
2059 || !codegen_results.crate_info.is_no_builtins.contains(&cnum));
2061 if skip_because_cfg_say_so || skip_because_lto {
2062 archive.remove_file(&f);
2073 // If we're creating a dylib, then we need to include the
2074 // whole of each object in our archive into that artifact. This is
2075 // because a `dylib` can be reused as an intermediate artifact.
2077 // Note, though, that we don't want to include the whole of a
2078 // compiler-builtins crate (e.g., compiler-rt) because it'll get
2079 // repeatedly linked anyway.
2080 if crate_type == CrateType::Dylib
2081 && codegen_results.crate_info.compiler_builtins != Some(cnum)
2083 cmd.link_whole_rlib(&fix_windows_verbatim_for_gcc(&dst));
2085 cmd.link_rlib(&fix_windows_verbatim_for_gcc(&dst));
2090 // Same thing as above, but for dynamic crates instead of static crates.
2091 fn add_dynamic_crate(cmd: &mut dyn Linker, sess: &Session, cratepath: &Path) {
2092 // Just need to tell the linker about where the library lives and
2094 let parent = cratepath.parent();
2095 if let Some(dir) = parent {
2096 cmd.include_path(&fix_windows_verbatim_for_gcc(dir));
2098 let filestem = cratepath.file_stem().unwrap().to_str().unwrap();
2099 cmd.link_rust_dylib(
2100 Symbol::intern(&unlib(&sess.target, filestem)),
2101 parent.unwrap_or_else(|| Path::new("")),
2106 /// Link in all of our upstream crates' native dependencies. Remember that all of these upstream
2107 /// native dependencies are all non-static dependencies. We've got two cases then:
2109 /// 1. The upstream crate is an rlib. In this case we *must* link in the native dependency because
2110 /// the rlib is just an archive.
2112 /// 2. The upstream crate is a dylib. In order to use the dylib, we have to have the dependency
2113 /// present on the system somewhere. Thus, we don't gain a whole lot from not linking in the
2114 /// dynamic dependency to this crate as well.
2116 /// The use case for this is a little subtle. In theory the native dependencies of a crate are
2117 /// purely an implementation detail of the crate itself, but the problem arises with generic and
2118 /// inlined functions. If a generic function calls a native function, then the generic function
2119 /// must be instantiated in the target crate, meaning that the native symbol must also be resolved
2120 /// in the target crate.
2121 fn add_upstream_native_libraries(
2122 cmd: &mut dyn Linker,
2124 codegen_results: &CodegenResults,
2125 crate_type: CrateType,
2127 // Be sure to use a topological sorting of crates because there may be
2128 // interdependencies between native libraries. When passing -nodefaultlibs,
2129 // for example, almost all native libraries depend on libc, so we have to
2130 // make sure that's all the way at the right (liblibc is near the base of
2131 // the dependency chain).
2133 // This passes RequireStatic, but the actual requirement doesn't matter,
2134 // we're just getting an ordering of crate numbers, we're not worried about
2136 let (_, data) = codegen_results
2140 .find(|(ty, _)| *ty == crate_type)
2141 .expect("failed to find crate type in dependency format list");
2143 let crates = &codegen_results.crate_info.used_crates_static;
2144 let mut last = (NativeLibKind::Unspecified, None);
2145 for &(cnum, _) in crates {
2146 for lib in codegen_results.crate_info.native_libraries[&cnum].iter() {
2147 // Skip if this library is the same as the last.
2148 last = if (lib.kind, lib.name) == last { continue } else { (lib.kind, lib.name) };
2150 let name = match lib.name {
2154 if !relevant_lib(sess, &lib) {
2157 let verbatim = lib.verbatim.unwrap_or(false);
2159 NativeLibKind::Dylib { as_needed } => {
2160 cmd.link_dylib(name, verbatim, as_needed.unwrap_or(true))
2162 NativeLibKind::Unspecified => cmd.link_dylib(name, verbatim, true),
2163 NativeLibKind::Framework { as_needed } => {
2164 cmd.link_framework(name, as_needed.unwrap_or(true))
2166 NativeLibKind::Static { bundle: Some(false), .. } => {
2167 // Link "static-nobundle" native libs only if the crate they originate from
2168 // is being linked statically to the current crate. If it's linked dynamically
2169 // or is an rlib already included via some other dylib crate, the symbols from
2170 // native libs will have already been included in that dylib.
2171 if data[cnum.as_usize() - 1] == Linkage::Static {
2172 cmd.link_staticlib(name, verbatim)
2175 // ignore statically included native libraries here as we've
2176 // already included them when we included the rust library
2178 NativeLibKind::Static { bundle: None | Some(true), .. } => {}
2179 NativeLibKind::RawDylib => {
2180 // FIXME(#58713): Proper handling for raw dylibs.
2181 bug!("raw_dylib feature not yet implemented");
2188 fn relevant_lib(sess: &Session, lib: &NativeLib) -> bool {
2190 Some(ref cfg) => rustc_attr::cfg_matches(cfg, &sess.parse_sess, None),
2195 fn are_upstream_rust_objects_already_included(sess: &Session) -> bool {
2197 config::Lto::Fat => true,
2198 config::Lto::Thin => {
2199 // If we defer LTO to the linker, we haven't run LTO ourselves, so
2200 // any upstream object files have not been copied yet.
2201 !sess.opts.cg.linker_plugin_lto.enabled()
2203 config::Lto::No | config::Lto::ThinLocal => false,
2207 fn add_apple_sdk(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavor) {
2208 let arch = &sess.target.arch;
2209 let os = &sess.target.os;
2210 let llvm_target = &sess.target.llvm_target;
2211 if sess.target.vendor != "apple"
2212 || !matches!(os.as_str(), "ios" | "tvos")
2213 || flavor != LinkerFlavor::Gcc
2217 let sdk_name = match (arch.as_str(), os.as_str()) {
2218 ("aarch64", "tvos") => "appletvos",
2219 ("x86_64", "tvos") => "appletvsimulator",
2220 ("arm", "ios") => "iphoneos",
2221 ("aarch64", "ios") if llvm_target.contains("macabi") => "macosx",
2222 ("aarch64", "ios") if llvm_target.contains("sim") => "iphonesimulator",
2223 ("aarch64", "ios") => "iphoneos",
2224 ("x86", "ios") => "iphonesimulator",
2225 ("x86_64", "ios") if llvm_target.contains("macabi") => "macosx",
2226 ("x86_64", "ios") => "iphonesimulator",
2228 sess.err(&format!("unsupported arch `{}` for os `{}`", arch, os));
2232 let sdk_root = match get_apple_sdk_root(sdk_name) {
2239 if llvm_target.contains("macabi") {
2240 cmd.args(&["-target", llvm_target])
2242 let arch_name = llvm_target.split('-').next().expect("LLVM target must have a hyphen");
2243 cmd.args(&["-arch", arch_name])
2245 cmd.args(&["-isysroot", &sdk_root, "-Wl,-syslibroot", &sdk_root]);
2248 fn get_apple_sdk_root(sdk_name: &str) -> Result<String, String> {
2249 // Following what clang does
2250 // (https://github.com/llvm/llvm-project/blob/
2251 // 296a80102a9b72c3eda80558fb78a3ed8849b341/clang/lib/Driver/ToolChains/Darwin.cpp#L1661-L1678)
2252 // to allow the SDK path to be set. (For clang, xcrun sets
2253 // SDKROOT; for rustc, the user or build system can set it, or we
2254 // can fall back to checking for xcrun on PATH.)
2255 if let Ok(sdkroot) = env::var("SDKROOT") {
2256 let p = Path::new(&sdkroot);
2258 // Ignore `SDKROOT` if it's clearly set for the wrong platform.
2260 if sdkroot.contains("TVSimulator.platform")
2261 || sdkroot.contains("MacOSX.platform") => {}
2263 if sdkroot.contains("TVOS.platform") || sdkroot.contains("MacOSX.platform") => {}
2265 if sdkroot.contains("iPhoneSimulator.platform")
2266 || sdkroot.contains("MacOSX.platform") => {}
2268 if sdkroot.contains("iPhoneOS.platform") || sdkroot.contains("MacOSX.platform") => {
2271 if sdkroot.contains("iPhoneOS.platform")
2272 || sdkroot.contains("iPhoneSimulator.platform") => {}
2273 // Ignore `SDKROOT` if it's not a valid path.
2274 _ if !p.is_absolute() || p == Path::new("/") || !p.exists() => {}
2275 _ => return Ok(sdkroot),
2279 Command::new("xcrun").arg("--show-sdk-path").arg("-sdk").arg(sdk_name).output().and_then(
2281 if output.status.success() {
2282 Ok(String::from_utf8(output.stdout).unwrap())
2284 let error = String::from_utf8(output.stderr);
2285 let error = format!("process exit with error: {}", error.unwrap());
2286 Err(io::Error::new(io::ErrorKind::Other, &error[..]))
2292 Ok(output) => Ok(output.trim().to_string()),
2293 Err(e) => Err(format!("failed to get {} SDK path: {}", sdk_name, e)),