1 use super::command::Command;
2 use super::symbol_export;
4 use rustc_span::symbol::sym;
6 use std::ffi::{OsStr, OsString};
7 use std::fs::{self, File};
8 use std::io::prelude::*;
9 use std::io::{self, BufWriter};
10 use std::path::{Path, PathBuf};
11 use std::{env, mem, str};
13 use rustc_hir::def_id::{CrateNum, LOCAL_CRATE};
14 use rustc_metadata::find_native_static_library;
15 use rustc_middle::middle::dependency_format::Linkage;
16 use rustc_middle::middle::exported_symbols::{ExportedSymbol, SymbolExportInfo, SymbolExportKind};
17 use rustc_middle::ty::TyCtxt;
18 use rustc_session::config::{self, CrateType, DebugInfo, LinkerPluginLto, Lto, OptLevel, Strip};
19 use rustc_session::Session;
20 use rustc_target::spec::{Cc, LinkOutputKind, LinkerFlavor, Lld};
22 use cc::windows_registry;
24 /// Disables non-English messages from localized linkers.
25 /// Such messages may cause issues with text encoding on Windows (#35785)
26 /// and prevent inspection of linker output in case of errors, which we occasionally do.
27 /// This should be acceptable because other messages from rustc are in English anyway,
28 /// and may also be desirable to improve searchability of the linker diagnostics.
29 pub fn disable_localization(linker: &mut Command) {
30 // No harm in setting both env vars simultaneously.
31 // Unix-style linkers.
32 linker.env("LC_ALL", "C");
34 linker.env("VSLANG", "1033");
37 // The third parameter is for env vars, used on windows to set up the
38 // path for MSVC to find its DLLs, and gcc to find its bundled
40 pub fn get_linker<'a>(
46 ) -> Box<dyn Linker + 'a> {
47 let msvc_tool = windows_registry::find_tool(&sess.opts.target_triple.triple(), "link.exe");
49 // If our linker looks like a batch script on Windows then to execute this
50 // we'll need to spawn `cmd` explicitly. This is primarily done to handle
51 // emscripten where the linker is `emcc.bat` and needs to be spawned as
52 // `cmd /c emcc.bat ...`.
54 // This worked historically but is needed manually since #42436 (regression
55 // was tagged as #42791) and some more info can be found on #44443 for
57 let mut cmd = match linker.to_str() {
58 Some(linker) if cfg!(windows) && linker.ends_with(".bat") => Command::bat_script(linker),
60 LinkerFlavor::Gnu(Cc::No, Lld::Yes)
61 | LinkerFlavor::Darwin(Cc::No, Lld::Yes)
62 | LinkerFlavor::WasmLld(Cc::No)
63 | LinkerFlavor::Msvc(Lld::Yes) => Command::lld(linker, flavor.lld_flavor()),
64 LinkerFlavor::Msvc(Lld::No)
65 if sess.opts.cg.linker.is_none() && sess.target.linker.is_none() =>
67 Command::new(msvc_tool.as_ref().map_or(linker, |t| t.path()))
69 _ => Command::new(linker),
73 // UWP apps have API restrictions enforced during Store submissions.
74 // To comply with the Windows App Certification Kit,
75 // MSVC needs to link with the Store versions of the runtime libraries (vcruntime, msvcrt, etc).
77 if matches!(flavor, LinkerFlavor::Msvc(..)) && t.vendor == "uwp" {
78 if let Some(ref tool) = msvc_tool {
79 let original_path = tool.path();
80 if let Some(ref root_lib_path) = original_path.ancestors().nth(4) {
81 let arch = match t.arch.as_ref() {
82 "x86_64" => Some("x64"),
84 "aarch64" => Some("arm64"),
88 if let Some(ref a) = arch {
89 // FIXME: Move this to `fn linker_with_args`.
90 let mut arg = OsString::from("/LIBPATH:");
91 arg.push(format!("{}\\lib\\{}\\store", root_lib_path.display(), a));
94 warn!("arch is not supported");
97 warn!("MSVC root path lib location not found");
100 warn!("link.exe not found");
104 // The compiler's sysroot often has some bundled tools, so add it to the
105 // PATH for the child.
106 let mut new_path = sess.get_tools_search_paths(self_contained);
107 let mut msvc_changed_path = false;
108 if sess.target.is_like_msvc {
109 if let Some(ref tool) = msvc_tool {
110 cmd.args(tool.args());
111 for &(ref k, ref v) in tool.env() {
113 new_path.extend(env::split_paths(v));
114 msvc_changed_path = true;
122 if !msvc_changed_path {
123 if let Some(path) = env::var_os("PATH") {
124 new_path.extend(env::split_paths(&path));
127 cmd.env("PATH", env::join_paths(new_path).unwrap());
129 // FIXME: Move `/LIBPATH` addition for uwp targets from the linker construction
130 // to the linker args construction.
131 assert!(cmd.get_args().is_empty() || sess.target.vendor == "uwp");
133 LinkerFlavor::Unix(Cc::No) if sess.target.os == "l4re" => {
134 Box::new(L4Bender::new(cmd, sess)) as Box<dyn Linker>
136 LinkerFlavor::WasmLld(Cc::No) => Box::new(WasmLd::new(cmd, sess)) as Box<dyn Linker>,
137 LinkerFlavor::Gnu(cc, _)
138 | LinkerFlavor::Darwin(cc, _)
139 | LinkerFlavor::WasmLld(cc)
140 | LinkerFlavor::Unix(cc) => Box::new(GccLinker {
144 hinted_static: false,
146 is_gnu: flavor.is_gnu(),
147 }) as Box<dyn Linker>,
148 LinkerFlavor::Msvc(..) => Box::new(MsvcLinker { cmd, sess }) as Box<dyn Linker>,
149 LinkerFlavor::EmCc => Box::new(EmLinker { cmd, sess }) as Box<dyn Linker>,
150 LinkerFlavor::Bpf => Box::new(BpfLinker { cmd, sess }) as Box<dyn Linker>,
151 LinkerFlavor::Ptx => Box::new(PtxLinker { cmd, sess }) as Box<dyn Linker>,
155 /// Linker abstraction used by `back::link` to build up the command to invoke a
158 /// This trait is the total list of requirements needed by `back::link` and
159 /// represents the meaning of each option being passed down. This trait is then
160 /// used to dispatch on whether a GNU-like linker (generally `ld.exe`) or an
161 /// MSVC linker (e.g., `link.exe`) is being used.
163 fn cmd(&mut self) -> &mut Command;
164 fn set_output_kind(&mut self, output_kind: LinkOutputKind, out_filename: &Path);
165 fn link_dylib(&mut self, lib: &str, verbatim: bool, as_needed: bool);
166 fn link_rust_dylib(&mut self, lib: &str, path: &Path);
167 fn link_framework(&mut self, framework: &str, as_needed: bool);
168 fn link_staticlib(&mut self, lib: &str, verbatim: bool);
169 fn link_rlib(&mut self, lib: &Path);
170 fn link_whole_rlib(&mut self, lib: &Path);
171 fn link_whole_staticlib(&mut self, lib: &str, verbatim: bool, search_path: &[PathBuf]);
172 fn include_path(&mut self, path: &Path);
173 fn framework_path(&mut self, path: &Path);
174 fn output_filename(&mut self, path: &Path);
175 fn add_object(&mut self, path: &Path);
176 fn gc_sections(&mut self, keep_metadata: bool);
177 fn no_gc_sections(&mut self);
178 fn full_relro(&mut self);
179 fn partial_relro(&mut self);
180 fn no_relro(&mut self);
181 fn optimize(&mut self);
182 fn pgo_gen(&mut self);
183 fn control_flow_guard(&mut self);
184 fn debuginfo(&mut self, strip: Strip, natvis_debugger_visualizers: &[PathBuf]);
185 fn no_crt_objects(&mut self);
186 fn no_default_libraries(&mut self);
187 fn export_symbols(&mut self, tmpdir: &Path, crate_type: CrateType, symbols: &[String]);
188 fn subsystem(&mut self, subsystem: &str);
189 fn linker_plugin_lto(&mut self);
190 fn add_eh_frame_header(&mut self) {}
191 fn add_no_exec(&mut self) {}
192 fn add_as_needed(&mut self) {}
193 fn reset_per_library_state(&mut self) {}
196 impl dyn Linker + '_ {
197 pub fn arg(&mut self, arg: impl AsRef<OsStr>) {
201 pub fn args(&mut self, args: impl IntoIterator<Item: AsRef<OsStr>>) {
202 self.cmd().args(args);
205 pub fn take_cmd(&mut self) -> Command {
206 mem::replace(self.cmd(), Command::new(""))
210 pub struct GccLinker<'a> {
214 hinted_static: bool, // Keeps track of the current hinting mode.
220 impl<'a> GccLinker<'a> {
221 /// Passes an argument directly to the linker.
223 /// When the linker is not ld-like such as when using a compiler as a linker, the argument is
224 /// prepended by `-Wl,`.
225 fn linker_arg(&mut self, arg: impl AsRef<OsStr>) -> &mut Self {
226 self.linker_args(&[arg]);
230 /// Passes a series of arguments directly to the linker.
232 /// When the linker is ld-like, the arguments are simply appended to the command. When the
233 /// linker is not ld-like such as when using a compiler as a linker, the arguments are joined by
234 /// commas to form an argument that is then prepended with `-Wl`. In this situation, only a
235 /// single argument is appended to the command to ensure that the order of the arguments is
236 /// preserved by the compiler.
237 fn linker_args(&mut self, args: &[impl AsRef<OsStr>]) -> &mut Self {
239 args.into_iter().for_each(|a| {
243 if !args.is_empty() {
244 let mut s = OsString::from("-Wl");
255 fn takes_hints(&self) -> bool {
256 // Really this function only returns true if the underlying linker
257 // configured for a compiler is binutils `ld.bfd` and `ld.gold`. We
258 // don't really have a foolproof way to detect that, so rule out some
259 // platforms where currently this is guaranteed to *not* be the case:
261 // * On OSX they have their own linker, not binutils'
262 // * For WebAssembly the only functional linker is LLD, which doesn't
263 // support hint flags
264 !self.sess.target.is_like_osx && !self.sess.target.is_like_wasm
267 // Some platforms take hints about whether a library is static or dynamic.
268 // For those that support this, we ensure we pass the option if the library
269 // was flagged "static" (most defaults are dynamic) to ensure that if
270 // libfoo.a and libfoo.so both exist that the right one is chosen.
271 fn hint_static(&mut self) {
272 if !self.takes_hints() {
275 if !self.hinted_static {
276 self.linker_arg("-Bstatic");
277 self.hinted_static = true;
281 fn hint_dynamic(&mut self) {
282 if !self.takes_hints() {
285 if self.hinted_static {
286 self.linker_arg("-Bdynamic");
287 self.hinted_static = false;
291 fn push_linker_plugin_lto_args(&mut self, plugin_path: Option<&OsStr>) {
292 if let Some(plugin_path) = plugin_path {
293 let mut arg = OsString::from("-plugin=");
294 arg.push(plugin_path);
295 self.linker_arg(&arg);
298 let opt_level = match self.sess.opts.optimize {
299 config::OptLevel::No => "O0",
300 config::OptLevel::Less => "O1",
301 config::OptLevel::Default | config::OptLevel::Size | config::OptLevel::SizeMin => "O2",
302 config::OptLevel::Aggressive => "O3",
305 if let Some(path) = &self.sess.opts.unstable_opts.profile_sample_use {
306 self.linker_arg(&format!("-plugin-opt=sample-profile={}", path.display()));
309 &format!("-plugin-opt={}", opt_level),
310 &format!("-plugin-opt=mcpu={}", self.target_cpu),
314 fn build_dylib(&mut self, out_filename: &Path) {
315 // On mac we need to tell the linker to let this library be rpathed
316 if self.sess.target.is_like_osx {
318 self.cmd.arg("-dynamiclib");
321 self.linker_arg("-dylib");
323 // Note that the `osx_rpath_install_name` option here is a hack
324 // purely to support rustbuild right now, we should get a more
325 // principled solution at some point to force the compiler to pass
326 // the right `-Wl,-install_name` with an `@rpath` in it.
327 if self.sess.opts.cg.rpath || self.sess.opts.unstable_opts.osx_rpath_install_name {
328 let mut rpath = OsString::from("@rpath/");
329 rpath.push(out_filename.file_name().unwrap());
330 self.linker_args(&[OsString::from("-install_name"), rpath]);
333 self.cmd.arg("-shared");
334 if self.sess.target.is_like_windows {
335 // The output filename already contains `dll_suffix` so
336 // the resulting import library will have a name in the
337 // form of libfoo.dll.a
339 out_filename.file_name().and_then(|file| file.to_str()).map(|file| {
342 self.sess.target.staticlib_prefix,
344 self.sess.target.staticlib_suffix
347 if let Some(implib_name) = implib_name {
348 let implib = out_filename.parent().map(|dir| dir.join(&implib_name));
349 if let Some(implib) = implib {
350 self.linker_arg(&format!("--out-implib={}", (*implib).to_str().unwrap()));
358 impl<'a> Linker for GccLinker<'a> {
359 fn cmd(&mut self) -> &mut Command {
363 fn set_output_kind(&mut self, output_kind: LinkOutputKind, out_filename: &Path) {
365 LinkOutputKind::DynamicNoPicExe => {
366 if !self.is_ld && self.is_gnu {
367 self.cmd.arg("-no-pie");
370 LinkOutputKind::DynamicPicExe => {
371 // noop on windows w/ gcc & ld, error w/ lld
372 if !self.sess.target.is_like_windows {
373 // `-pie` works for both gcc wrapper and ld.
374 self.cmd.arg("-pie");
377 LinkOutputKind::StaticNoPicExe => {
378 // `-static` works for both gcc wrapper and ld.
379 self.cmd.arg("-static");
380 if !self.is_ld && self.is_gnu {
381 self.cmd.arg("-no-pie");
384 LinkOutputKind::StaticPicExe => {
386 // Note that combination `-static -pie` doesn't work as expected
387 // for the gcc wrapper, `-static` in that case suppresses `-pie`.
388 self.cmd.arg("-static-pie");
390 // `--no-dynamic-linker` and `-z text` are not strictly necessary for producing
391 // a static pie, but currently passed because gcc and clang pass them.
392 // The former suppresses the `INTERP` ELF header specifying dynamic linker,
393 // which is otherwise implicitly injected by ld (but not lld).
394 // The latter doesn't change anything, only ensures that everything is pic.
395 self.cmd.args(&["-static", "-pie", "--no-dynamic-linker", "-z", "text"]);
398 LinkOutputKind::DynamicDylib => self.build_dylib(out_filename),
399 LinkOutputKind::StaticDylib => {
400 self.cmd.arg("-static");
401 self.build_dylib(out_filename);
403 LinkOutputKind::WasiReactorExe => {
404 self.linker_args(&["--entry", "_initialize"]);
407 // VxWorks compiler driver introduced `--static-crt` flag specifically for rustc,
408 // it switches linking for libc and similar system libraries to static without using
409 // any `#[link]` attributes in the `libc` crate, see #72782 for details.
410 // FIXME: Switch to using `#[link]` attributes in the `libc` crate
411 // similarly to other targets.
412 if self.sess.target.os == "vxworks"
415 LinkOutputKind::StaticNoPicExe
416 | LinkOutputKind::StaticPicExe
417 | LinkOutputKind::StaticDylib
420 self.cmd.arg("--static-crt");
424 fn link_dylib(&mut self, lib: &str, verbatim: bool, as_needed: bool) {
425 if self.sess.target.os == "illumos" && lib == "c" {
426 // libc will be added via late_link_args on illumos so that it will
427 // appear last in the library search order.
428 // FIXME: This should be replaced by a more complete and generic
429 // mechanism for controlling the order of library arguments passed
434 if self.sess.target.is_like_osx {
435 // FIXME(81490): ld64 doesn't support these flags but macOS 11
436 // has -needed-l{} / -needed_library {}
437 // but we have no way to detect that here.
438 self.sess.emit_warning(errors::Ld64UnimplementedModifier);
439 } else if self.is_gnu && !self.sess.target.is_like_windows {
440 self.linker_arg("--no-as-needed");
442 self.sess.emit_warning(errors::LinkerUnsupportedModifier);
446 self.cmd.arg(format!("-l{}{lib}", if verbatim && self.is_gnu { ":" } else { "" },));
448 if self.sess.target.is_like_osx {
449 // See above FIXME comment
450 } else if self.is_gnu && !self.sess.target.is_like_windows {
451 self.linker_arg("--as-needed");
455 fn link_staticlib(&mut self, lib: &str, verbatim: bool) {
457 self.cmd.arg(format!("-l{}{lib}", if verbatim && self.is_gnu { ":" } else { "" },));
459 fn link_rlib(&mut self, lib: &Path) {
463 fn include_path(&mut self, path: &Path) {
464 self.cmd.arg("-L").arg(path);
466 fn framework_path(&mut self, path: &Path) {
467 self.cmd.arg("-F").arg(path);
469 fn output_filename(&mut self, path: &Path) {
470 self.cmd.arg("-o").arg(path);
472 fn add_object(&mut self, path: &Path) {
475 fn full_relro(&mut self) {
476 self.linker_args(&["-zrelro", "-znow"]);
478 fn partial_relro(&mut self) {
479 self.linker_arg("-zrelro");
481 fn no_relro(&mut self) {
482 self.linker_arg("-znorelro");
485 fn link_rust_dylib(&mut self, lib: &str, _path: &Path) {
487 self.cmd.arg(format!("-l{}", lib));
490 fn link_framework(&mut self, framework: &str, as_needed: bool) {
493 // FIXME(81490): ld64 as of macOS 11 supports the -needed_framework
494 // flag but we have no way to detect that here.
495 // self.cmd.arg("-needed_framework").arg(framework);
496 self.sess.emit_warning(errors::Ld64UnimplementedModifier);
498 self.cmd.arg("-framework").arg(framework);
501 // Here we explicitly ask that the entire archive is included into the
502 // result artifact. For more details see #15460, but the gist is that
503 // the linker will strip away any unused objects in the archive if we
504 // don't otherwise explicitly reference them. This can occur for
505 // libraries which are just providing bindings, libraries with generic
507 fn link_whole_staticlib(&mut self, lib: &str, verbatim: bool, search_path: &[PathBuf]) {
509 let target = &self.sess.target;
510 if !target.is_like_osx {
511 self.linker_arg("--whole-archive");
512 self.cmd.arg(format!("-l{}{lib}", if verbatim && self.is_gnu { ":" } else { "" },));
513 self.linker_arg("--no-whole-archive");
515 // -force_load is the macOS equivalent of --whole-archive, but it
516 // involves passing the full path to the library to link.
517 self.linker_arg("-force_load");
518 let lib = find_native_static_library(lib, Some(verbatim), search_path, &self.sess);
519 self.linker_arg(&lib);
523 fn link_whole_rlib(&mut self, lib: &Path) {
525 if self.sess.target.is_like_osx {
526 self.linker_arg("-force_load");
527 self.linker_arg(&lib);
529 self.linker_arg("--whole-archive").cmd.arg(lib);
530 self.linker_arg("--no-whole-archive");
534 fn gc_sections(&mut self, keep_metadata: bool) {
535 // The dead_strip option to the linker specifies that functions and data
536 // unreachable by the entry point will be removed. This is quite useful
537 // with Rust's compilation model of compiling libraries at a time into
538 // one object file. For example, this brings hello world from 1.7MB to
541 // Note that this is done for both executables and dynamic libraries. We
542 // won't get much benefit from dylibs because LLVM will have already
543 // stripped away as much as it could. This has not been seen to impact
544 // link times negatively.
546 // -dead_strip can't be part of the pre_link_args because it's also used
547 // for partial linking when using multiple codegen units (-r). So we
549 if self.sess.target.is_like_osx {
550 self.linker_arg("-dead_strip");
552 // If we're building a dylib, we don't use --gc-sections because LLVM
553 // has already done the best it can do, and we also don't want to
554 // eliminate the metadata. If we're building an executable, however,
555 // --gc-sections drops the size of hello world from 1.8MB to 597K, a 67%
557 } else if (self.is_gnu || self.sess.target.is_like_wasm) && !keep_metadata {
558 self.linker_arg("--gc-sections");
562 fn no_gc_sections(&mut self) {
563 if self.is_gnu || self.sess.target.is_like_wasm {
564 self.linker_arg("--no-gc-sections");
568 fn optimize(&mut self) {
569 if !self.is_gnu && !self.sess.target.is_like_wasm {
573 // GNU-style linkers support optimization with -O. GNU ld doesn't
574 // need a numeric argument, but other linkers do.
575 if self.sess.opts.optimize == config::OptLevel::Default
576 || self.sess.opts.optimize == config::OptLevel::Aggressive
578 self.linker_arg("-O1");
582 fn pgo_gen(&mut self) {
587 // If we're doing PGO generation stuff and on a GNU-like linker, use the
588 // "-u" flag to properly pull in the profiler runtime bits.
590 // This is because LLVM otherwise won't add the needed initialization
591 // for us on Linux (though the extra flag should be harmless if it
594 // See https://reviews.llvm.org/D14033 and https://reviews.llvm.org/D14030.
596 // Though it may be worth to try to revert those changes upstream, since
597 // the overhead of the initialization should be minor.
599 self.cmd.arg("__llvm_profile_runtime");
602 fn control_flow_guard(&mut self) {}
604 fn debuginfo(&mut self, strip: Strip, _: &[PathBuf]) {
605 // MacOS linker doesn't support stripping symbols directly anymore.
606 if self.sess.target.is_like_osx {
612 Strip::Debuginfo => {
613 // The illumos linker does not support --strip-debug although
614 // it does support --strip-all as a compatibility alias for -s.
615 // The --strip-debug case is handled by running an external
616 // `strip` utility as a separate step after linking.
617 if self.sess.target.os != "illumos" {
618 self.linker_arg("--strip-debug");
622 self.linker_arg("--strip-all");
627 fn no_crt_objects(&mut self) {
629 self.cmd.arg("-nostartfiles");
633 fn no_default_libraries(&mut self) {
635 self.cmd.arg("-nodefaultlibs");
639 fn export_symbols(&mut self, tmpdir: &Path, crate_type: CrateType, symbols: &[String]) {
640 // Symbol visibility in object files typically takes care of this.
641 if crate_type == CrateType::Executable {
642 let should_export_executable_symbols =
643 self.sess.opts.unstable_opts.export_executable_symbols;
644 if self.sess.target.override_export_symbols.is_none()
645 && !should_export_executable_symbols
651 // We manually create a list of exported symbols to ensure we don't expose any more.
652 // The object files have far more public symbols than we actually want to export,
653 // so we hide them all here.
655 if !self.sess.target.limit_rdylib_exports {
659 // FIXME(#99978) hide #[no_mangle] symbols for proc-macros
661 let is_windows = self.sess.target.is_like_windows;
662 let path = tmpdir.join(if is_windows { "list.def" } else { "list" });
664 debug!("EXPORTED SYMBOLS:");
666 if self.sess.target.is_like_osx {
667 // Write a plain, newline-separated list of symbols
668 let res: io::Result<()> = try {
669 let mut f = BufWriter::new(File::create(&path)?);
672 writeln!(f, "_{}", sym)?;
675 if let Err(error) = res {
676 self.sess.emit_fatal(errors::LibDefWriteFailure { error });
678 } else if is_windows {
679 let res: io::Result<()> = try {
680 let mut f = BufWriter::new(File::create(&path)?);
682 // .def file similar to MSVC one but without LIBRARY section
683 // because LD doesn't like when it's empty
684 writeln!(f, "EXPORTS")?;
685 for symbol in symbols {
686 debug!(" _{}", symbol);
687 writeln!(f, " {}", symbol)?;
690 if let Err(error) = res {
691 self.sess.emit_fatal(errors::LibDefWriteFailure { error });
694 // Write an LD version script
695 let res: io::Result<()> = try {
696 let mut f = BufWriter::new(File::create(&path)?);
698 if !symbols.is_empty() {
699 writeln!(f, " global:")?;
702 writeln!(f, " {};", sym)?;
705 writeln!(f, "\n local:\n *;\n}};")?;
707 if let Err(error) = res {
708 self.sess.emit_fatal(errors::VersionScriptWriteFailure { error });
712 if self.sess.target.is_like_osx {
713 self.linker_args(&[OsString::from("-exported_symbols_list"), path.into()]);
714 } else if self.sess.target.is_like_solaris {
715 self.linker_args(&[OsString::from("-M"), path.into()]);
718 self.linker_arg(path);
720 let mut arg = OsString::from("--version-script=");
722 self.linker_arg(arg);
727 fn subsystem(&mut self, subsystem: &str) {
728 self.linker_arg("--subsystem");
729 self.linker_arg(&subsystem);
732 fn reset_per_library_state(&mut self) {
733 self.hint_dynamic(); // Reset to default before returning the composed command line.
736 fn linker_plugin_lto(&mut self) {
737 match self.sess.opts.cg.linker_plugin_lto {
738 LinkerPluginLto::Disabled => {
741 LinkerPluginLto::LinkerPluginAuto => {
742 self.push_linker_plugin_lto_args(None);
744 LinkerPluginLto::LinkerPlugin(ref path) => {
745 self.push_linker_plugin_lto_args(Some(path.as_os_str()));
750 // Add the `GNU_EH_FRAME` program header which is required to locate unwinding information.
751 // Some versions of `gcc` add it implicitly, some (e.g. `musl-gcc`) don't,
752 // so we just always add it.
753 fn add_eh_frame_header(&mut self) {
754 self.linker_arg("--eh-frame-hdr");
757 fn add_no_exec(&mut self) {
758 if self.sess.target.is_like_windows {
759 self.linker_arg("--nxcompat");
760 } else if self.is_gnu {
761 self.linker_arg("-znoexecstack");
765 fn add_as_needed(&mut self) {
766 if self.is_gnu && !self.sess.target.is_like_windows {
767 self.linker_arg("--as-needed");
768 } else if self.sess.target.is_like_solaris {
769 // -z ignore is the Solaris equivalent to the GNU ld --as-needed option
770 self.linker_args(&["-z", "ignore"]);
775 pub struct MsvcLinker<'a> {
780 impl<'a> Linker for MsvcLinker<'a> {
781 fn cmd(&mut self) -> &mut Command {
785 fn set_output_kind(&mut self, output_kind: LinkOutputKind, out_filename: &Path) {
787 LinkOutputKind::DynamicNoPicExe
788 | LinkOutputKind::DynamicPicExe
789 | LinkOutputKind::StaticNoPicExe
790 | LinkOutputKind::StaticPicExe => {}
791 LinkOutputKind::DynamicDylib | LinkOutputKind::StaticDylib => {
792 self.cmd.arg("/DLL");
793 let mut arg: OsString = "/IMPLIB:".into();
794 arg.push(out_filename.with_extension("dll.lib"));
797 LinkOutputKind::WasiReactorExe => {
798 panic!("can't link as reactor on non-wasi target");
803 fn link_rlib(&mut self, lib: &Path) {
806 fn add_object(&mut self, path: &Path) {
810 fn gc_sections(&mut self, _keep_metadata: bool) {
811 // MSVC's ICF (Identical COMDAT Folding) link optimization is
812 // slow for Rust and thus we disable it by default when not in
813 // optimization build.
814 if self.sess.opts.optimize != config::OptLevel::No {
815 self.cmd.arg("/OPT:REF,ICF");
817 // It is necessary to specify NOICF here, because /OPT:REF
818 // implies ICF by default.
819 self.cmd.arg("/OPT:REF,NOICF");
823 fn no_gc_sections(&mut self) {
824 self.cmd.arg("/OPT:NOREF,NOICF");
827 fn link_dylib(&mut self, lib: &str, verbatim: bool, _as_needed: bool) {
828 self.cmd.arg(format!("{}{}", lib, if verbatim { "" } else { ".lib" }));
831 fn link_rust_dylib(&mut self, lib: &str, path: &Path) {
832 // When producing a dll, the MSVC linker may not actually emit a
833 // `foo.lib` file if the dll doesn't actually export any symbols, so we
834 // check to see if the file is there and just omit linking to it if it's
836 let name = format!("{}.dll.lib", lib);
837 if path.join(&name).exists() {
842 fn link_staticlib(&mut self, lib: &str, verbatim: bool) {
843 self.cmd.arg(format!("{}{}", lib, if verbatim { "" } else { ".lib" }));
846 fn full_relro(&mut self) {
850 fn partial_relro(&mut self) {
854 fn no_relro(&mut self) {
858 fn no_crt_objects(&mut self) {
862 fn no_default_libraries(&mut self) {
863 self.cmd.arg("/NODEFAULTLIB");
866 fn include_path(&mut self, path: &Path) {
867 let mut arg = OsString::from("/LIBPATH:");
872 fn output_filename(&mut self, path: &Path) {
873 let mut arg = OsString::from("/OUT:");
878 fn framework_path(&mut self, _path: &Path) {
879 bug!("frameworks are not supported on windows")
881 fn link_framework(&mut self, _framework: &str, _as_needed: bool) {
882 bug!("frameworks are not supported on windows")
885 fn link_whole_staticlib(&mut self, lib: &str, verbatim: bool, _search_path: &[PathBuf]) {
886 self.cmd.arg(format!("/WHOLEARCHIVE:{}{}", lib, if verbatim { "" } else { ".lib" }));
888 fn link_whole_rlib(&mut self, path: &Path) {
889 let mut arg = OsString::from("/WHOLEARCHIVE:");
893 fn optimize(&mut self) {
894 // Needs more investigation of `/OPT` arguments
897 fn pgo_gen(&mut self) {
898 // Nothing needed here.
901 fn control_flow_guard(&mut self) {
902 self.cmd.arg("/guard:cf");
905 fn debuginfo(&mut self, strip: Strip, natvis_debugger_visualizers: &[PathBuf]) {
908 // This will cause the Microsoft linker to generate a PDB file
909 // from the CodeView line tables in the object files.
910 self.cmd.arg("/DEBUG");
912 // This will cause the Microsoft linker to embed .natvis info into the PDB file
913 let natvis_dir_path = self.sess.sysroot.join("lib\\rustlib\\etc");
914 if let Ok(natvis_dir) = fs::read_dir(&natvis_dir_path) {
915 for entry in natvis_dir {
918 let path = entry.path();
919 if path.extension() == Some("natvis".as_ref()) {
920 let mut arg = OsString::from("/NATVIS:");
926 self.sess.emit_warning(errors::NoNatvisDirectory { error });
932 // This will cause the Microsoft linker to embed .natvis info for all crates into the PDB file
933 for path in natvis_debugger_visualizers {
934 let mut arg = OsString::from("/NATVIS:");
939 Strip::Debuginfo | Strip::Symbols => {
940 self.cmd.arg("/DEBUG:NONE");
945 // Currently the compiler doesn't use `dllexport` (an LLVM attribute) to
946 // export symbols from a dynamic library. When building a dynamic library,
947 // however, we're going to want some symbols exported, so this function
948 // generates a DEF file which lists all the symbols.
950 // The linker will read this `*.def` file and export all the symbols from
951 // the dynamic library. Note that this is not as simple as just exporting
952 // all the symbols in the current crate (as specified by `codegen.reachable`)
953 // but rather we also need to possibly export the symbols of upstream
954 // crates. Upstream rlibs may be linked statically to this dynamic library,
955 // in which case they may continue to transitively be used and hence need
956 // their symbols exported.
957 fn export_symbols(&mut self, tmpdir: &Path, crate_type: CrateType, symbols: &[String]) {
958 // Symbol visibility takes care of this typically
959 if crate_type == CrateType::Executable {
960 let should_export_executable_symbols =
961 self.sess.opts.unstable_opts.export_executable_symbols;
962 if !should_export_executable_symbols {
967 let path = tmpdir.join("lib.def");
968 let res: io::Result<()> = try {
969 let mut f = BufWriter::new(File::create(&path)?);
971 // Start off with the standard module name header and then go
972 // straight to exports.
973 writeln!(f, "LIBRARY")?;
974 writeln!(f, "EXPORTS")?;
975 for symbol in symbols {
976 debug!(" _{}", symbol);
977 writeln!(f, " {}", symbol)?;
980 if let Err(error) = res {
981 self.sess.emit_fatal(errors::LibDefWriteFailure { error });
983 let mut arg = OsString::from("/DEF:");
988 fn subsystem(&mut self, subsystem: &str) {
989 // Note that previous passes of the compiler validated this subsystem,
990 // so we just blindly pass it to the linker.
991 self.cmd.arg(&format!("/SUBSYSTEM:{}", subsystem));
993 // Windows has two subsystems we're interested in right now, the console
994 // and windows subsystems. These both implicitly have different entry
995 // points (starting symbols). The console entry point starts with
996 // `mainCRTStartup` and the windows entry point starts with
997 // `WinMainCRTStartup`. These entry points, defined in system libraries,
998 // will then later probe for either `main` or `WinMain`, respectively to
999 // start the application.
1001 // In Rust we just always generate a `main` function so we want control
1002 // to always start there, so we force the entry point on the windows
1003 // subsystem to be `mainCRTStartup` to get everything booted up
1006 // For more information see RFC #1665
1007 if subsystem == "windows" {
1008 self.cmd.arg("/ENTRY:mainCRTStartup");
1012 fn linker_plugin_lto(&mut self) {
1016 fn add_no_exec(&mut self) {
1017 self.cmd.arg("/NXCOMPAT");
1021 pub struct EmLinker<'a> {
1026 impl<'a> Linker for EmLinker<'a> {
1027 fn cmd(&mut self) -> &mut Command {
1031 fn set_output_kind(&mut self, _output_kind: LinkOutputKind, _out_filename: &Path) {}
1033 fn include_path(&mut self, path: &Path) {
1034 self.cmd.arg("-L").arg(path);
1037 fn link_staticlib(&mut self, lib: &str, _verbatim: bool) {
1038 self.cmd.arg("-l").arg(lib);
1041 fn output_filename(&mut self, path: &Path) {
1042 self.cmd.arg("-o").arg(path);
1045 fn add_object(&mut self, path: &Path) {
1049 fn link_dylib(&mut self, lib: &str, verbatim: bool, _as_needed: bool) {
1050 // Emscripten always links statically
1051 self.link_staticlib(lib, verbatim);
1054 fn link_whole_staticlib(&mut self, lib: &str, verbatim: bool, _search_path: &[PathBuf]) {
1056 self.link_staticlib(lib, verbatim);
1059 fn link_whole_rlib(&mut self, lib: &Path) {
1061 self.link_rlib(lib);
1064 fn link_rust_dylib(&mut self, lib: &str, _path: &Path) {
1065 self.link_dylib(lib, false, true);
1068 fn link_rlib(&mut self, lib: &Path) {
1069 self.add_object(lib);
1072 fn full_relro(&mut self) {
1076 fn partial_relro(&mut self) {
1080 fn no_relro(&mut self) {
1084 fn framework_path(&mut self, _path: &Path) {
1085 bug!("frameworks are not supported on Emscripten")
1088 fn link_framework(&mut self, _framework: &str, _as_needed: bool) {
1089 bug!("frameworks are not supported on Emscripten")
1092 fn gc_sections(&mut self, _keep_metadata: bool) {
1096 fn no_gc_sections(&mut self) {
1100 fn optimize(&mut self) {
1101 // Emscripten performs own optimizations
1102 self.cmd.arg(match self.sess.opts.optimize {
1103 OptLevel::No => "-O0",
1104 OptLevel::Less => "-O1",
1105 OptLevel::Default => "-O2",
1106 OptLevel::Aggressive => "-O3",
1107 OptLevel::Size => "-Os",
1108 OptLevel::SizeMin => "-Oz",
1112 fn pgo_gen(&mut self) {
1113 // noop, but maybe we need something like the gnu linker?
1116 fn control_flow_guard(&mut self) {}
1118 fn debuginfo(&mut self, _strip: Strip, _: &[PathBuf]) {
1119 // Preserve names or generate source maps depending on debug info
1120 self.cmd.arg(match self.sess.opts.debuginfo {
1121 DebugInfo::None => "-g0",
1122 DebugInfo::Limited => "--profiling-funcs",
1123 DebugInfo::Full => "-g",
1127 fn no_crt_objects(&mut self) {}
1129 fn no_default_libraries(&mut self) {
1130 self.cmd.arg("-nodefaultlibs");
1133 fn export_symbols(&mut self, _tmpdir: &Path, _crate_type: CrateType, symbols: &[String]) {
1134 debug!("EXPORTED SYMBOLS:");
1138 let mut arg = OsString::from("EXPORTED_FUNCTIONS=");
1139 let encoded = serde_json::to_string(
1140 &symbols.iter().map(|sym| "_".to_owned() + sym).collect::<Vec<_>>(),
1143 debug!("{}", encoded);
1150 fn subsystem(&mut self, _subsystem: &str) {
1154 fn linker_plugin_lto(&mut self) {
1159 pub struct WasmLd<'a> {
1164 impl<'a> WasmLd<'a> {
1165 fn new(mut cmd: Command, sess: &'a Session) -> WasmLd<'a> {
1166 // If the atomics feature is enabled for wasm then we need a whole bunch
1169 // * `--shared-memory` - the link won't even succeed without this, flags
1170 // the one linear memory as `shared`
1172 // * `--max-memory=1G` - when specifying a shared memory this must also
1173 // be specified. We conservatively choose 1GB but users should be able
1174 // to override this with `-C link-arg`.
1176 // * `--import-memory` - it doesn't make much sense for memory to be
1177 // exported in a threaded module because typically you're
1178 // sharing memory and instantiating the module multiple times. As a
1179 // result if it were exported then we'd just have no sharing.
1181 // On wasm32-unknown-unknown, we also export symbols for glue code to use:
1182 // * `--export=*tls*` - when `#[thread_local]` symbols are used these
1183 // symbols are how the TLS segments are initialized and configured.
1184 if sess.target_features.contains(&sym::atomics) {
1185 cmd.arg("--shared-memory");
1186 cmd.arg("--max-memory=1073741824");
1187 cmd.arg("--import-memory");
1188 if sess.target.os == "unknown" {
1189 cmd.arg("--export=__wasm_init_tls");
1190 cmd.arg("--export=__tls_size");
1191 cmd.arg("--export=__tls_align");
1192 cmd.arg("--export=__tls_base");
1195 WasmLd { cmd, sess }
1199 impl<'a> Linker for WasmLd<'a> {
1200 fn cmd(&mut self) -> &mut Command {
1204 fn set_output_kind(&mut self, output_kind: LinkOutputKind, _out_filename: &Path) {
1206 LinkOutputKind::DynamicNoPicExe
1207 | LinkOutputKind::DynamicPicExe
1208 | LinkOutputKind::StaticNoPicExe
1209 | LinkOutputKind::StaticPicExe => {}
1210 LinkOutputKind::DynamicDylib | LinkOutputKind::StaticDylib => {
1211 self.cmd.arg("--no-entry");
1213 LinkOutputKind::WasiReactorExe => {
1214 self.cmd.arg("--entry");
1215 self.cmd.arg("_initialize");
1220 fn link_dylib(&mut self, lib: &str, _verbatim: bool, _as_needed: bool) {
1221 self.cmd.arg("-l").arg(lib);
1224 fn link_staticlib(&mut self, lib: &str, _verbatim: bool) {
1225 self.cmd.arg("-l").arg(lib);
1228 fn link_rlib(&mut self, lib: &Path) {
1232 fn include_path(&mut self, path: &Path) {
1233 self.cmd.arg("-L").arg(path);
1236 fn framework_path(&mut self, _path: &Path) {
1237 panic!("frameworks not supported")
1240 fn output_filename(&mut self, path: &Path) {
1241 self.cmd.arg("-o").arg(path);
1244 fn add_object(&mut self, path: &Path) {
1248 fn full_relro(&mut self) {}
1250 fn partial_relro(&mut self) {}
1252 fn no_relro(&mut self) {}
1254 fn link_rust_dylib(&mut self, lib: &str, _path: &Path) {
1255 self.cmd.arg("-l").arg(lib);
1258 fn link_framework(&mut self, _framework: &str, _as_needed: bool) {
1259 panic!("frameworks not supported")
1262 fn link_whole_staticlib(&mut self, lib: &str, _verbatim: bool, _search_path: &[PathBuf]) {
1263 self.cmd.arg("-l").arg(lib);
1266 fn link_whole_rlib(&mut self, lib: &Path) {
1270 fn gc_sections(&mut self, _keep_metadata: bool) {
1271 self.cmd.arg("--gc-sections");
1274 fn no_gc_sections(&mut self) {
1275 self.cmd.arg("--no-gc-sections");
1278 fn optimize(&mut self) {
1279 self.cmd.arg(match self.sess.opts.optimize {
1280 OptLevel::No => "-O0",
1281 OptLevel::Less => "-O1",
1282 OptLevel::Default => "-O2",
1283 OptLevel::Aggressive => "-O3",
1284 // Currently LLD doesn't support `Os` and `Oz`, so pass through `O2`
1286 OptLevel::Size => "-O2",
1287 OptLevel::SizeMin => "-O2",
1291 fn pgo_gen(&mut self) {}
1293 fn debuginfo(&mut self, strip: Strip, _: &[PathBuf]) {
1296 Strip::Debuginfo => {
1297 self.cmd.arg("--strip-debug");
1300 self.cmd.arg("--strip-all");
1305 fn control_flow_guard(&mut self) {}
1307 fn no_crt_objects(&mut self) {}
1309 fn no_default_libraries(&mut self) {}
1311 fn export_symbols(&mut self, _tmpdir: &Path, _crate_type: CrateType, symbols: &[String]) {
1312 for sym in symbols {
1313 self.cmd.arg("--export").arg(&sym);
1316 // LLD will hide these otherwise-internal symbols since it only exports
1317 // symbols explicitly passed via the `--export` flags above and hides all
1318 // others. Various bits and pieces of wasm32-unknown-unknown tooling use
1319 // this, so be sure these symbols make their way out of the linker as well.
1320 if self.sess.target.os == "unknown" {
1321 self.cmd.arg("--export=__heap_base");
1322 self.cmd.arg("--export=__data_end");
1326 fn subsystem(&mut self, _subsystem: &str) {}
1328 fn linker_plugin_lto(&mut self) {
1329 // Do nothing for now
1333 /// Linker shepherd script for L4Re (Fiasco)
1334 pub struct L4Bender<'a> {
1337 hinted_static: bool,
1340 impl<'a> Linker for L4Bender<'a> {
1341 fn link_dylib(&mut self, _lib: &str, _verbatim: bool, _as_needed: bool) {
1342 bug!("dylibs are not supported on L4Re");
1344 fn link_staticlib(&mut self, lib: &str, _verbatim: bool) {
1346 self.cmd.arg(format!("-PC{}", lib));
1348 fn link_rlib(&mut self, lib: &Path) {
1352 fn include_path(&mut self, path: &Path) {
1353 self.cmd.arg("-L").arg(path);
1355 fn framework_path(&mut self, _: &Path) {
1356 bug!("frameworks are not supported on L4Re");
1358 fn output_filename(&mut self, path: &Path) {
1359 self.cmd.arg("-o").arg(path);
1362 fn add_object(&mut self, path: &Path) {
1366 fn full_relro(&mut self) {
1367 self.cmd.arg("-zrelro");
1368 self.cmd.arg("-znow");
1371 fn partial_relro(&mut self) {
1372 self.cmd.arg("-zrelro");
1375 fn no_relro(&mut self) {
1376 self.cmd.arg("-znorelro");
1379 fn cmd(&mut self) -> &mut Command {
1383 fn set_output_kind(&mut self, _output_kind: LinkOutputKind, _out_filename: &Path) {}
1385 fn link_rust_dylib(&mut self, _: &str, _: &Path) {
1386 panic!("Rust dylibs not supported");
1389 fn link_framework(&mut self, _framework: &str, _as_needed: bool) {
1390 bug!("frameworks not supported on L4Re");
1393 fn link_whole_staticlib(&mut self, lib: &str, _verbatim: bool, _search_path: &[PathBuf]) {
1395 self.cmd.arg("--whole-archive").arg(format!("-l{}", lib));
1396 self.cmd.arg("--no-whole-archive");
1399 fn link_whole_rlib(&mut self, lib: &Path) {
1401 self.cmd.arg("--whole-archive").arg(lib).arg("--no-whole-archive");
1404 fn gc_sections(&mut self, keep_metadata: bool) {
1406 self.cmd.arg("--gc-sections");
1410 fn no_gc_sections(&mut self) {
1411 self.cmd.arg("--no-gc-sections");
1414 fn optimize(&mut self) {
1415 // GNU-style linkers support optimization with -O. GNU ld doesn't
1416 // need a numeric argument, but other linkers do.
1417 if self.sess.opts.optimize == config::OptLevel::Default
1418 || self.sess.opts.optimize == config::OptLevel::Aggressive
1420 self.cmd.arg("-O1");
1424 fn pgo_gen(&mut self) {}
1426 fn debuginfo(&mut self, strip: Strip, _: &[PathBuf]) {
1429 Strip::Debuginfo => {
1430 self.cmd().arg("--strip-debug");
1433 self.cmd().arg("--strip-all");
1438 fn no_default_libraries(&mut self) {
1439 self.cmd.arg("-nostdlib");
1442 fn export_symbols(&mut self, _: &Path, _: CrateType, _: &[String]) {
1443 // ToDo, not implemented, copy from GCC
1444 self.sess.emit_warning(errors::L4BenderExportingSymbolsUnimplemented);
1448 fn subsystem(&mut self, subsystem: &str) {
1449 self.cmd.arg(&format!("--subsystem {}", subsystem));
1452 fn reset_per_library_state(&mut self) {
1453 self.hint_static(); // Reset to default before returning the composed command line.
1456 fn linker_plugin_lto(&mut self) {}
1458 fn control_flow_guard(&mut self) {}
1460 fn no_crt_objects(&mut self) {}
1463 impl<'a> L4Bender<'a> {
1464 pub fn new(cmd: Command, sess: &'a Session) -> L4Bender<'a> {
1465 L4Bender { cmd: cmd, sess: sess, hinted_static: false }
1468 fn hint_static(&mut self) {
1469 if !self.hinted_static {
1470 self.cmd.arg("-static");
1471 self.hinted_static = true;
1476 fn for_each_exported_symbols_include_dep<'tcx>(
1478 crate_type: CrateType,
1479 mut callback: impl FnMut(ExportedSymbol<'tcx>, SymbolExportInfo, CrateNum),
1481 for &(symbol, info) in tcx.exported_symbols(LOCAL_CRATE).iter() {
1482 callback(symbol, info, LOCAL_CRATE);
1485 let formats = tcx.dependency_formats(());
1486 let deps = formats.iter().find_map(|(t, list)| (*t == crate_type).then_some(list)).unwrap();
1488 for (index, dep_format) in deps.iter().enumerate() {
1489 let cnum = CrateNum::new(index + 1);
1490 // For each dependency that we are linking to statically ...
1491 if *dep_format == Linkage::Static {
1492 for &(symbol, info) in tcx.exported_symbols(cnum).iter() {
1493 callback(symbol, info, cnum);
1499 pub(crate) fn exported_symbols(tcx: TyCtxt<'_>, crate_type: CrateType) -> Vec<String> {
1500 if let Some(ref exports) = tcx.sess.target.override_export_symbols {
1501 return exports.iter().map(ToString::to_string).collect();
1504 let mut symbols = Vec::new();
1506 let export_threshold = symbol_export::crates_export_threshold(&[crate_type]);
1507 for_each_exported_symbols_include_dep(tcx, crate_type, |symbol, info, cnum| {
1508 if info.level.is_below_threshold(export_threshold) {
1509 symbols.push(symbol_export::symbol_name_for_instance_in_crate(tcx, symbol, cnum));
1516 pub(crate) fn linked_symbols(
1518 crate_type: CrateType,
1519 ) -> Vec<(String, SymbolExportKind)> {
1521 CrateType::Executable | CrateType::Cdylib | CrateType::Dylib => (),
1522 CrateType::Staticlib | CrateType::ProcMacro | CrateType::Rlib => {
1527 let mut symbols = Vec::new();
1529 let export_threshold = symbol_export::crates_export_threshold(&[crate_type]);
1530 for_each_exported_symbols_include_dep(tcx, crate_type, |symbol, info, cnum| {
1531 if info.level.is_below_threshold(export_threshold) || info.used {
1533 symbol_export::linking_symbol_name_for_instance_in_crate(tcx, symbol, cnum),
1542 /// Much simplified and explicit CLI for the NVPTX linker. The linker operates
1543 /// with bitcode and uses LLVM backend to generate a PTX assembly.
1544 pub struct PtxLinker<'a> {
1549 impl<'a> Linker for PtxLinker<'a> {
1550 fn cmd(&mut self) -> &mut Command {
1554 fn set_output_kind(&mut self, _output_kind: LinkOutputKind, _out_filename: &Path) {}
1556 fn link_rlib(&mut self, path: &Path) {
1557 self.cmd.arg("--rlib").arg(path);
1560 fn link_whole_rlib(&mut self, path: &Path) {
1561 self.cmd.arg("--rlib").arg(path);
1564 fn include_path(&mut self, path: &Path) {
1565 self.cmd.arg("-L").arg(path);
1568 fn debuginfo(&mut self, _strip: Strip, _: &[PathBuf]) {
1569 self.cmd.arg("--debug");
1572 fn add_object(&mut self, path: &Path) {
1573 self.cmd.arg("--bitcode").arg(path);
1576 fn optimize(&mut self) {
1577 match self.sess.lto() {
1578 Lto::Thin | Lto::Fat | Lto::ThinLocal => {
1579 self.cmd.arg("-Olto");
1586 fn output_filename(&mut self, path: &Path) {
1587 self.cmd.arg("-o").arg(path);
1590 fn link_dylib(&mut self, _lib: &str, _verbatim: bool, _as_needed: bool) {
1591 panic!("external dylibs not supported")
1594 fn link_rust_dylib(&mut self, _lib: &str, _path: &Path) {
1595 panic!("external dylibs not supported")
1598 fn link_staticlib(&mut self, _lib: &str, _verbatim: bool) {
1599 panic!("staticlibs not supported")
1602 fn link_whole_staticlib(&mut self, _lib: &str, _verbatim: bool, _search_path: &[PathBuf]) {
1603 panic!("staticlibs not supported")
1606 fn framework_path(&mut self, _path: &Path) {
1607 panic!("frameworks not supported")
1610 fn link_framework(&mut self, _framework: &str, _as_needed: bool) {
1611 panic!("frameworks not supported")
1614 fn full_relro(&mut self) {}
1616 fn partial_relro(&mut self) {}
1618 fn no_relro(&mut self) {}
1620 fn gc_sections(&mut self, _keep_metadata: bool) {}
1622 fn no_gc_sections(&mut self) {}
1624 fn pgo_gen(&mut self) {}
1626 fn no_crt_objects(&mut self) {}
1628 fn no_default_libraries(&mut self) {}
1630 fn control_flow_guard(&mut self) {}
1632 fn export_symbols(&mut self, _tmpdir: &Path, _crate_type: CrateType, _symbols: &[String]) {}
1634 fn subsystem(&mut self, _subsystem: &str) {}
1636 fn linker_plugin_lto(&mut self) {}
1639 pub struct BpfLinker<'a> {
1644 impl<'a> Linker for BpfLinker<'a> {
1645 fn cmd(&mut self) -> &mut Command {
1649 fn set_output_kind(&mut self, _output_kind: LinkOutputKind, _out_filename: &Path) {}
1651 fn link_rlib(&mut self, path: &Path) {
1655 fn link_whole_rlib(&mut self, path: &Path) {
1659 fn include_path(&mut self, path: &Path) {
1660 self.cmd.arg("-L").arg(path);
1663 fn debuginfo(&mut self, _strip: Strip, _: &[PathBuf]) {
1664 self.cmd.arg("--debug");
1667 fn add_object(&mut self, path: &Path) {
1671 fn optimize(&mut self) {
1672 self.cmd.arg(match self.sess.opts.optimize {
1673 OptLevel::No => "-O0",
1674 OptLevel::Less => "-O1",
1675 OptLevel::Default => "-O2",
1676 OptLevel::Aggressive => "-O3",
1677 OptLevel::Size => "-Os",
1678 OptLevel::SizeMin => "-Oz",
1682 fn output_filename(&mut self, path: &Path) {
1683 self.cmd.arg("-o").arg(path);
1686 fn link_dylib(&mut self, _lib: &str, _verbatim: bool, _as_needed: bool) {
1687 panic!("external dylibs not supported")
1690 fn link_rust_dylib(&mut self, _lib: &str, _path: &Path) {
1691 panic!("external dylibs not supported")
1694 fn link_staticlib(&mut self, _lib: &str, _verbatim: bool) {
1695 panic!("staticlibs not supported")
1698 fn link_whole_staticlib(&mut self, _lib: &str, _verbatim: bool, _search_path: &[PathBuf]) {
1699 panic!("staticlibs not supported")
1702 fn framework_path(&mut self, _path: &Path) {
1703 panic!("frameworks not supported")
1706 fn link_framework(&mut self, _framework: &str, _as_needed: bool) {
1707 panic!("frameworks not supported")
1710 fn full_relro(&mut self) {}
1712 fn partial_relro(&mut self) {}
1714 fn no_relro(&mut self) {}
1716 fn gc_sections(&mut self, _keep_metadata: bool) {}
1718 fn no_gc_sections(&mut self) {}
1720 fn pgo_gen(&mut self) {}
1722 fn no_crt_objects(&mut self) {}
1724 fn no_default_libraries(&mut self) {}
1726 fn control_flow_guard(&mut self) {}
1728 fn export_symbols(&mut self, tmpdir: &Path, _crate_type: CrateType, symbols: &[String]) {
1729 let path = tmpdir.join("symbols");
1730 let res: io::Result<()> = try {
1731 let mut f = BufWriter::new(File::create(&path)?);
1732 for sym in symbols {
1733 writeln!(f, "{}", sym)?;
1736 if let Err(error) = res {
1737 self.sess.emit_fatal(errors::SymbolFileWriteFailure { error });
1739 self.cmd.arg("--export-symbols").arg(&path);
1743 fn subsystem(&mut self, _subsystem: &str) {}
1745 fn linker_plugin_lto(&mut self) {}