1 use rustc_arena
::TypedArena
;
2 use rustc_ast
::CRATE_NODE_ID
;
3 use rustc_data_structures
::fx
::{FxHashSet, FxIndexMap}
;
4 use rustc_data_structures
::memmap
::Mmap
;
5 use rustc_data_structures
::temp_dir
::MaybeTempDir
;
6 use rustc_errors
::{ErrorGuaranteed, Handler}
;
7 use rustc_fs_util
::fix_windows_verbatim_for_gcc
;
8 use rustc_hir
::def_id
::CrateNum
;
9 use rustc_metadata
::fs
::{emit_metadata, METADATA_FILENAME}
;
10 use rustc_middle
::middle
::dependency_format
::Linkage
;
11 use rustc_middle
::middle
::exported_symbols
::SymbolExportKind
;
12 use rustc_session
::config
::{self, CFGuard, CrateType, DebugInfo, LdImpl, Strip}
;
13 use rustc_session
::config
::{OutputFilenames, OutputType, PrintRequest, SplitDwarfKind}
;
14 use rustc_session
::cstore
::DllImport
;
15 use rustc_session
::output
::{check_file_is_writeable, invalid_output_for_target, out_filename}
;
16 use rustc_session
::search_paths
::PathKind
;
17 use rustc_session
::utils
::NativeLibKind
;
18 /// For all the linkers we support, and information they might
19 /// need out of the shared crate context before we get rid of it.
20 use rustc_session
::{filesearch, Session}
;
21 use rustc_span
::symbol
::Symbol
;
22 use rustc_span
::DebuggerVisualizerFile
;
23 use rustc_target
::spec
::crt_objects
::{CrtObjects, CrtObjectsFallback}
;
24 use rustc_target
::spec
::{LinkOutputKind, LinkerFlavor, LldFlavor, SplitDebuginfo}
;
25 use rustc_target
::spec
::{PanicStrategy, RelocModel, RelroLevel, SanitizerSet, Target}
;
27 use super::archive
::{find_library, ArchiveBuilder, ArchiveBuilderBuilder}
;
28 use super::command
::Command
;
29 use super::linker
::{self, Linker}
;
30 use super::metadata
::{create_rmeta_file, MetadataPosition}
;
31 use super::rpath
::{self, RPathConfig}
;
32 use crate::{looks_like_rust_object_file, CodegenResults, CompiledModule, CrateInfo, NativeLib}
;
34 use cc
::windows_registry
;
36 use tempfile
::Builder
as TempFileBuilder
;
38 use std
::borrow
::Borrow
;
39 use std
::cell
::OnceCell
;
40 use std
::collections
::BTreeSet
;
41 use std
::ffi
::OsString
;
42 use std
::fs
::{File, OpenOptions}
;
43 use std
::io
::{BufWriter, Write}
;
45 use std
::path
::{Path, PathBuf}
;
46 use std
::process
::{ExitStatus, Output, Stdio}
;
47 use std
::{ascii, char, env, fmt, fs, io, mem, str}
;
49 pub fn ensure_removed(diag_handler
: &Handler
, path
: &Path
) {
50 if let Err(e
) = fs
::remove_file(path
) {
51 if e
.kind() != io
::ErrorKind
::NotFound
{
52 diag_handler
.err(&format
!("failed to remove {}: {}", path
.display(), e
));
57 /// Performs the linkage portion of the compilation phase. This will generate all
58 /// of the requested outputs for this compilation session.
59 pub fn link_binary
<'a
>(
61 archive_builder_builder
: &dyn ArchiveBuilderBuilder
,
62 codegen_results
: &CodegenResults
,
63 outputs
: &OutputFilenames
,
64 ) -> Result
<(), ErrorGuaranteed
> {
65 let _timer
= sess
.timer("link_binary");
66 let output_metadata
= sess
.opts
.output_types
.contains_key(&OutputType
::Metadata
);
67 for &crate_type
in sess
.crate_types().iter() {
68 // Ignore executable crates if we have -Z no-codegen, as they will error.
69 if (sess
.opts
.unstable_opts
.no_codegen
|| !sess
.opts
.output_types
.should_codegen())
71 && crate_type
== CrateType
::Executable
76 if invalid_output_for_target(sess
, crate_type
) {
78 "invalid output type `{:?}` for target os `{}`",
80 sess
.opts
.target_triple
84 sess
.time("link_binary_check_files_are_writeable", || {
85 for obj
in codegen_results
.modules
.iter().filter_map(|m
| m
.object
.as_ref()) {
86 check_file_is_writeable(obj
, sess
);
90 if outputs
.outputs
.should_link() {
91 let tmpdir
= TempFileBuilder
::new()
94 .unwrap_or_else(|err
| sess
.fatal(&format
!("couldn't create a temp dir: {}", err
)));
95 let path
= MaybeTempDir
::new(tmpdir
, sess
.opts
.cg
.save_temps
);
96 let out_filename
= out_filename(
100 codegen_results
.crate_info
.local_crate_name
.as_str(),
104 let _timer
= sess
.timer("link_rlib");
105 info
!("preparing rlib to {:?}", out_filename
);
108 archive_builder_builder
,
113 .build(&out_filename
);
115 CrateType
::Staticlib
=> {
118 archive_builder_builder
,
127 archive_builder_builder
,
135 if sess
.opts
.json_artifact_notifications
{
136 sess
.parse_sess
.span_diagnostic
.emit_artifact_notification(&out_filename
, "link");
139 if sess
.prof
.enabled() {
140 if let Some(artifact_name
) = out_filename
.file_name() {
141 // Record size for self-profiling
142 let file_size
= std
::fs
::metadata(&out_filename
).map(|m
| m
.len()).unwrap_or(0);
144 sess
.prof
.artifact_size(
146 artifact_name
.to_string_lossy(),
154 // Remove the temporary object file and metadata if we aren't saving temps.
155 sess
.time("link_binary_remove_temps", || {
156 // If the user requests that temporaries are saved, don't delete any.
157 if sess
.opts
.cg
.save_temps
{
161 let maybe_remove_temps_from_module
=
162 |preserve_objects
: bool
, preserve_dwarf_objects
: bool
, module
: &CompiledModule
| {
163 if !preserve_objects
{
164 if let Some(ref obj
) = module
.object
{
165 ensure_removed(sess
.diagnostic(), obj
);
169 if !preserve_dwarf_objects
{
170 if let Some(ref dwo_obj
) = module
.dwarf_object
{
171 ensure_removed(sess
.diagnostic(), dwo_obj
);
176 let remove_temps_from_module
=
177 |module
: &CompiledModule
| maybe_remove_temps_from_module(false, false, module
);
179 // Otherwise, always remove the metadata and allocator module temporaries.
180 if let Some(ref metadata_module
) = codegen_results
.metadata_module
{
181 remove_temps_from_module(metadata_module
);
184 if let Some(ref allocator_module
) = codegen_results
.allocator_module
{
185 remove_temps_from_module(allocator_module
);
188 // If no requested outputs require linking, then the object temporaries should
190 if !sess
.opts
.output_types
.should_link() {
194 // Potentially keep objects for their debuginfo.
195 let (preserve_objects
, preserve_dwarf_objects
) = preserve_objects_for_their_debuginfo(sess
);
196 debug
!(?preserve_objects
, ?preserve_dwarf_objects
);
198 for module
in &codegen_results
.modules
{
199 maybe_remove_temps_from_module(preserve_objects
, preserve_dwarf_objects
, module
);
206 pub fn each_linked_rlib(
208 f
: &mut dyn FnMut(CrateNum
, &Path
),
209 ) -> Result
<(), String
> {
210 let crates
= info
.used_crates
.iter();
212 for (ty
, list
) in info
.dependency_formats
.iter() {
214 CrateType
::Executable
215 | CrateType
::Staticlib
217 | CrateType
::ProcMacro
=> {
224 let Some(fmts
) = fmts
else {
225 return Err("could not find formats for rlibs".to_string());
227 for &cnum
in crates
{
228 match fmts
.get(cnum
.as_usize() - 1) {
229 Some(&Linkage
::NotLinked
| &Linkage
::IncludedFromDylib
) => continue,
231 None
=> return Err("could not find formats for rlibs".to_string()),
233 let name
= info
.crate_name
[&cnum
];
234 let used_crate_source
= &info
.used_crate_source
[&cnum
];
235 if let Some((path
, _
)) = &used_crate_source
.rlib
{
238 if used_crate_source
.rmeta
.is_some() {
240 "could not find rlib for: `{}`, found rmeta (metadata) file",
244 return Err(format
!("could not find rlib for: `{}`", name
));
251 /// Create an 'rlib'.
253 /// An rlib in its current incarnation is essentially a renamed .a file. The rlib primarily contains
254 /// the object file of the crate, but it also contains all of the object files from native
255 /// libraries. This is done by unzipping native libraries and inserting all of the contents into
259 archive_builder_builder
: &dyn ArchiveBuilderBuilder
,
260 codegen_results
: &CodegenResults
,
262 tmpdir
: &MaybeTempDir
,
263 ) -> Result
<Box
<dyn ArchiveBuilder
<'a
> + 'a
>, ErrorGuaranteed
> {
264 let lib_search_paths
= archive_search_paths(sess
);
266 let mut ab
= archive_builder_builder
.new_archive_builder(sess
);
268 let trailing_metadata
= match flavor
{
269 RlibFlavor
::Normal
=> {
270 let (metadata
, metadata_position
) =
271 create_rmeta_file(sess
, codegen_results
.metadata
.raw_data());
272 let metadata
= emit_metadata(sess
, &metadata
, tmpdir
);
273 match metadata_position
{
274 MetadataPosition
::First
=> {
275 // Most of the time metadata in rlib files is wrapped in a "dummy" object
276 // file for the target platform so the rlib can be processed entirely by
277 // normal linkers for the platform. Sometimes this is not possible however.
278 // If it is possible however, placing the metadata object first improves
279 // performance of getting metadata from rlibs.
280 ab
.add_file(&metadata
);
283 MetadataPosition
::Last
=> Some(metadata
),
287 RlibFlavor
::StaticlibBase
=> None
,
290 for m
in &codegen_results
.modules
{
291 if let Some(obj
) = m
.object
.as_ref() {
295 if let Some(dwarf_obj
) = m
.dwarf_object
.as_ref() {
296 ab
.add_file(dwarf_obj
);
301 RlibFlavor
::Normal
=> {}
302 RlibFlavor
::StaticlibBase
=> {
303 let obj
= codegen_results
.allocator_module
.as_ref().and_then(|m
| m
.object
.as_ref());
304 if let Some(obj
) = obj
{
310 // Note that in this loop we are ignoring the value of `lib.cfg`. That is,
311 // we may not be configured to actually include a static library if we're
312 // adding it here. That's because later when we consume this rlib we'll
313 // decide whether we actually needed the static library or not.
315 // To do this "correctly" we'd need to keep track of which libraries added
316 // which object files to the archive. We don't do that here, however. The
317 // #[link(cfg(..))] feature is unstable, though, and only intended to get
318 // liblibc working. In that sense the check below just indicates that if
319 // there are any libraries we want to omit object files for at link time we
320 // just exclude all custom object files.
322 // Eventually if we want to stabilize or flesh out the #[link(cfg(..))]
323 // feature then we'll need to figure out how to record what objects were
324 // loaded from the libraries found here and then encode that into the
325 // metadata of the rlib we're generating somehow.
326 for lib
in codegen_results
.crate_info
.used_libraries
.iter() {
328 NativeLibKind
::Static { bundle: None | Some(true), whole_archive: Some(true) }
329 if flavor
== RlibFlavor
::Normal
=>
331 // Don't allow mixing +bundle with +whole_archive since an rlib may contain
332 // multiple native libs, some of which are +whole-archive and some of which are
333 // -whole-archive and it isn't clear how we can currently handle such a
334 // situation correctly.
335 // See https://github.com/rust-lang/rust/issues/88085#issuecomment-901050897
337 "the linking modifiers `+bundle` and `+whole-archive` are not compatible \
338 with each other when generating rlibs",
341 NativeLibKind
::Static { bundle: None | Some(true), .. }
=> {}
342 NativeLibKind
::Static { bundle: Some(false), .. }
343 | NativeLibKind
::Dylib { .. }
344 | NativeLibKind
::Framework { .. }
345 | NativeLibKind
::RawDylib
346 | NativeLibKind
::LinkArg
347 | NativeLibKind
::Unspecified
=> continue,
349 if let Some(name
) = lib
.name
{
351 find_library(name
.as_str(), lib
.verbatim
.unwrap_or(false), &lib_search_paths
, sess
);
352 ab
.add_archive(&location
, Box
::new(|_
| false)).unwrap_or_else(|e
| {
354 "failed to add native library {}: {}",
355 location
.to_string_lossy(),
362 for (raw_dylib_name
, raw_dylib_imports
) in
363 collate_raw_dylibs(sess
, &codegen_results
.crate_info
.used_libraries
)?
365 let output_path
= archive_builder_builder
.create_dll_import_lib(
372 ab
.add_archive(&output_path
, Box
::new(|_
| false)).unwrap_or_else(|e
| {
373 sess
.fatal(&format
!("failed to add native library {}: {}", output_path
.display(), e
));
377 if let Some(trailing_metadata
) = trailing_metadata
{
378 // Note that it is important that we add all of our non-object "magical
379 // files" *after* all of the object files in the archive. The reason for
380 // this is as follows:
382 // * When performing LTO, this archive will be modified to remove
383 // objects from above. The reason for this is described below.
385 // * When the system linker looks at an archive, it will attempt to
386 // determine the architecture of the archive in order to see whether its
389 // The algorithm for this detection is: iterate over the files in the
390 // archive. Skip magical SYMDEF names. Interpret the first file as an
391 // object file. Read architecture from the object file.
393 // * As one can probably see, if "metadata" and "foo.bc" were placed
394 // before all of the objects, then the architecture of this archive would
395 // not be correctly inferred once 'foo.o' is removed.
397 // * Most of the time metadata in rlib files is wrapped in a "dummy" object
398 // file for the target platform so the rlib can be processed entirely by
399 // normal linkers for the platform. Sometimes this is not possible however.
401 // Basically, all this means is that this code should not move above the
403 ab
.add_file(&trailing_metadata
);
409 /// Extract all symbols defined in raw-dylib libraries, collated by library name.
411 /// If we have multiple extern blocks that specify symbols defined in the same raw-dylib library,
412 /// then the CodegenResults value contains one NativeLib instance for each block. However, the
413 /// linker appears to expect only a single import library for each library used, so we need to
414 /// collate the symbols together by library name before generating the import libraries.
415 fn collate_raw_dylibs(
417 used_libraries
: &[NativeLib
],
418 ) -> Result
<Vec
<(String
, Vec
<DllImport
>)>, ErrorGuaranteed
> {
419 // Use index maps to preserve original order of imports and libraries.
420 let mut dylib_table
= FxIndexMap
::<String
, FxIndexMap
<Symbol
, &DllImport
>>::default();
422 for lib
in used_libraries
{
423 if lib
.kind
== NativeLibKind
::RawDylib
{
424 let ext
= if matches
!(lib
.verbatim
, Some(true)) { "" }
else { ".dll" }
;
425 let name
= format
!("{}{}", lib
.name
.expect("unnamed raw-dylib library"), ext
);
426 let imports
= dylib_table
.entry(name
.clone()).or_default();
427 for import
in &lib
.dll_imports
{
428 if let Some(old_import
) = imports
.insert(import
.name
, import
) {
429 // FIXME: when we add support for ordinals, figure out if we need to do anything
430 // if we have two DllImport values with the same name but different ordinals.
431 if import
.calling_convention
!= old_import
.calling_convention
{
435 "multiple declarations of external function `{}` from \
436 library `{}` have different calling conventions",
445 sess
.compile_status()?
;
448 .map(|(name
, imports
)| {
449 (name
, imports
.into_iter().map(|(_
, import
)| import
.clone()).collect())
454 /// Create a static archive.
456 /// This is essentially the same thing as an rlib, but it also involves adding all of the upstream
457 /// crates' objects into the archive. This will slurp in all of the native libraries of upstream
458 /// dependencies as well.
460 /// Additionally, there's no way for us to link dynamic libraries, so we warn about all dynamic
461 /// library dependencies that they're not linked in.
463 /// There's no need to include metadata in a static archive, so ensure to not link in the metadata
464 /// object file (and also don't prepare the archive with a metadata file).
465 fn link_staticlib
<'a
>(
467 archive_builder_builder
: &dyn ArchiveBuilderBuilder
,
468 codegen_results
: &CodegenResults
,
470 tempdir
: &MaybeTempDir
,
471 ) -> Result
<(), ErrorGuaranteed
> {
472 info
!("preparing staticlib to {:?}", out_filename
);
473 let mut ab
= link_rlib(
475 archive_builder_builder
,
477 RlibFlavor
::StaticlibBase
,
480 let mut all_native_libs
= vec
![];
482 let res
= each_linked_rlib(&codegen_results
.crate_info
, &mut |cnum
, path
| {
483 let name
= codegen_results
.crate_info
.crate_name
[&cnum
];
484 let native_libs
= &codegen_results
.crate_info
.native_libraries
[&cnum
];
486 // Here when we include the rlib into our staticlib we need to make a
487 // decision whether to include the extra object files along the way.
488 // These extra object files come from statically included native
489 // libraries, but they may be cfg'd away with #[link(cfg(..))].
491 // This unstable feature, though, only needs liblibc to work. The only
492 // use case there is where musl is statically included in liblibc.rlib,
493 // so if we don't want the included version we just need to skip it. As
494 // a result the logic here is that if *any* linked library is cfg'd away
495 // we just skip all object files.
497 // Clearly this is not sufficient for a general purpose feature, and
498 // we'd want to read from the library's metadata to determine which
499 // object files come from where and selectively skip them.
500 let skip_object_files
= native_libs
.iter().any(|lib
| {
501 matches
!(lib
.kind
, NativeLibKind
::Static { bundle: None | Some(true), .. }
)
502 && !relevant_lib(sess
, lib
)
505 let lto
= are_upstream_rust_objects_already_included(sess
)
506 && !ignored_for_lto(sess
, &codegen_results
.crate_info
, cnum
);
508 // Ignoring obj file starting with the crate name
509 // as simple comparison is not enough - there
510 // might be also an extra name suffix
511 let obj_start
= name
.as_str().to_owned();
515 Box
::new(move |fname
: &str| {
516 // Ignore metadata files, no matter the name.
517 if fname
== METADATA_FILENAME
{
521 // Don't include Rust objects if LTO is enabled
522 if lto
&& looks_like_rust_object_file(fname
) {
526 // Otherwise if this is *not* a rust object and we're skipping
527 // objects then skip this file
528 if skip_object_files
&& (!fname
.starts_with(&obj_start
) || !fname
.ends_with(".o")) {
532 // ok, don't skip this
538 all_native_libs
.extend(codegen_results
.crate_info
.native_libraries
[&cnum
].iter().cloned());
540 if let Err(e
) = res
{
544 ab
.build(out_filename
);
546 if !all_native_libs
.is_empty() {
547 if sess
.opts
.prints
.contains(&PrintRequest
::NativeStaticLibs
) {
548 print_native_static_libs(sess
, &all_native_libs
);
555 fn escape_stdout_stderr_string(s
: &[u8]) -> String
{
556 str::from_utf8(s
).map(|s
| s
.to_owned()).unwrap_or_else(|_
| {
557 let mut x
= "Non-UTF-8 output: ".to_string();
558 x
.extend(s
.iter().flat_map(|&b
| ascii
::escape_default(b
)).map(char::from
));
563 /// Use `thorin` (rust implementation of a dwarf packaging utility) to link DWARF objects into a
565 fn link_dwarf_object
<'a
>(
567 cg_results
: &CodegenResults
,
568 executable_out_filename
: &Path
,
570 let dwp_out_filename
= executable_out_filename
.with_extension("dwp");
571 debug
!(?dwp_out_filename
, ?executable_out_filename
);
574 struct ThorinSession
<Relocations
> {
575 arena_data
: TypedArena
<Vec
<u8>>,
576 arena_mmap
: TypedArena
<Mmap
>,
577 arena_relocations
: TypedArena
<Relocations
>,
580 impl<Relocations
> ThorinSession
<Relocations
> {
581 fn alloc_mmap
<'arena
>(&'arena
self, data
: Mmap
) -> &'arena Mmap
{
582 (*self.arena_mmap
.alloc(data
)).borrow()
586 impl<Relocations
> thorin
::Session
<Relocations
> for ThorinSession
<Relocations
> {
587 fn alloc_data
<'arena
>(&'arena
self, data
: Vec
<u8>) -> &'arena
[u8] {
588 (*self.arena_data
.alloc(data
)).borrow()
591 fn alloc_relocation
<'arena
>(&'arena
self, data
: Relocations
) -> &'arena Relocations
{
592 (*self.arena_relocations
.alloc(data
)).borrow()
595 fn read_input
<'arena
>(&'arena
self, path
: &Path
) -> std
::io
::Result
<&'arena
[u8]> {
596 let file
= File
::open(&path
)?
;
597 let mmap
= (unsafe { Mmap::map(file) }
)?
;
598 Ok(self.alloc_mmap(mmap
))
602 match sess
.time("run_thorin", || -> Result
<(), thorin
::Error
> {
603 let thorin_sess
= ThorinSession
::default();
604 let mut package
= thorin
::DwarfPackage
::new(&thorin_sess
);
606 // Input objs contain .o/.dwo files from the current crate.
607 match sess
.opts
.unstable_opts
.split_dwarf_kind
{
608 SplitDwarfKind
::Single
=> {
609 for input_obj
in cg_results
.modules
.iter().filter_map(|m
| m
.object
.as_ref()) {
610 package
.add_input_object(input_obj
)?
;
613 SplitDwarfKind
::Split
=> {
614 for input_obj
in cg_results
.modules
.iter().filter_map(|m
| m
.dwarf_object
.as_ref()) {
615 package
.add_input_object(input_obj
)?
;
620 // Input rlibs contain .o/.dwo files from dependencies.
621 let input_rlibs
= cg_results
625 .filter_map(|csource
| csource
.rlib
.as_ref())
626 .map(|(path
, _
)| path
);
627 for input_rlib
in input_rlibs
{
629 package
.add_input_object(input_rlib
)?
;
632 // Failing to read the referenced objects is expected for dependencies where the path in the
633 // executable will have been cleaned by Cargo, but the referenced objects will be contained
634 // within rlibs provided as inputs.
636 // If paths have been remapped, then .o/.dwo files from the current crate also won't be
637 // found, but are provided explicitly above.
639 // Adding an executable is primarily done to make `thorin` check that all the referenced
640 // dwarf objects are found in the end.
641 package
.add_executable(
642 &executable_out_filename
,
643 thorin
::MissingReferencedObjectBehaviour
::Skip
,
646 let output
= package
.finish()?
.write()?
;
647 let mut output_stream
= BufWriter
::new(
653 .open(dwp_out_filename
)?
,
655 output_stream
.write_all(&output
)?
;
656 output_stream
.flush()?
;
662 sess
.struct_err("linking dwarf objects with thorin failed")
663 .note(&format
!("{:?}", e
))
665 sess
.abort_if_errors();
670 /// Create a dynamic library or executable.
672 /// This will invoke the system linker/cc to create the resulting file. This links to all upstream
674 fn link_natively
<'a
>(
676 archive_builder_builder
: &dyn ArchiveBuilderBuilder
,
677 crate_type
: CrateType
,
679 codegen_results
: &CodegenResults
,
681 ) -> Result
<(), ErrorGuaranteed
> {
682 info
!("preparing {:?} to {:?}", crate_type
, out_filename
);
683 let (linker_path
, flavor
) = linker_and_flavor(sess
);
684 let mut cmd
= linker_with_args(
688 archive_builder_builder
,
695 linker
::disable_localization(&mut cmd
);
697 for &(ref k
, ref v
) in sess
.target
.link_env
.as_ref() {
698 cmd
.env(k
.as_ref(), v
.as_ref());
700 for k
in sess
.target
.link_env_remove
.as_ref() {
701 cmd
.env_remove(k
.as_ref());
704 if sess
.opts
.prints
.contains(&PrintRequest
::LinkArgs
) {
705 println
!("{:?}", &cmd
);
708 // May have not found libraries in the right formats.
709 sess
.abort_if_errors();
711 // Invoke the system linker
713 let retry_on_segfault
= env
::var("RUSTC_RETRY_LINKER_ON_SEGFAULT").is_ok();
714 let unknown_arg_regex
=
715 Regex
::new(r
"(unknown|unrecognized) (command line )?(option|argument)").unwrap();
720 prog
= sess
.time("run_linker", || exec_linker(sess
, &cmd
, out_filename
, tmpdir
));
721 let Ok(ref output
) = prog
else {
724 if output
.status
.success() {
727 let mut out
= output
.stderr
.clone();
728 out
.extend(&output
.stdout
);
729 let out
= String
::from_utf8_lossy(&out
);
731 // Check to see if the link failed with an error message that indicates it
732 // doesn't recognize the -no-pie option. If so, re-perform the link step
733 // without it. This is safe because if the linker doesn't support -no-pie
734 // then it should not default to linking executables as pie. Different
735 // versions of gcc seem to use different quotes in the error message so
736 // don't check for them.
737 if sess
.target
.linker_is_gnu
738 && flavor
!= LinkerFlavor
::Ld
739 && unknown_arg_regex
.is_match(&out
)
740 && out
.contains("-no-pie")
741 && cmd
.get_args().iter().any(|e
| e
.to_string_lossy() == "-no-pie")
743 info
!("linker output: {:?}", out
);
744 warn
!("Linker does not support -no-pie command line option. Retrying without.");
745 for arg
in cmd
.take_args() {
746 if arg
.to_string_lossy() != "-no-pie" {
754 // Detect '-static-pie' used with an older version of gcc or clang not supporting it.
755 // Fallback from '-static-pie' to '-static' in that case.
756 if sess
.target
.linker_is_gnu
757 && flavor
!= LinkerFlavor
::Ld
758 && unknown_arg_regex
.is_match(&out
)
759 && (out
.contains("-static-pie") || out
.contains("--no-dynamic-linker"))
760 && cmd
.get_args().iter().any(|e
| e
.to_string_lossy() == "-static-pie")
762 info
!("linker output: {:?}", out
);
764 "Linker does not support -static-pie command line option. Retrying with -static instead."
766 // Mirror `add_(pre,post)_link_objects` to replace CRT objects.
767 let self_contained
= crt_objects_fallback(sess
, crate_type
);
768 let opts
= &sess
.target
;
769 let pre_objects
= if self_contained
{
770 &opts
.pre_link_objects_fallback
772 &opts
.pre_link_objects
774 let post_objects
= if self_contained
{
775 &opts
.post_link_objects_fallback
777 &opts
.post_link_objects
779 let get_objects
= |objects
: &CrtObjects
, kind
| {
785 .map(|obj
| get_object_file_path(sess
, obj
, self_contained
).into_os_string())
788 let pre_objects_static_pie
= get_objects(pre_objects
, LinkOutputKind
::StaticPicExe
);
789 let post_objects_static_pie
= get_objects(post_objects
, LinkOutputKind
::StaticPicExe
);
790 let mut pre_objects_static
= get_objects(pre_objects
, LinkOutputKind
::StaticNoPicExe
);
791 let mut post_objects_static
= get_objects(post_objects
, LinkOutputKind
::StaticNoPicExe
);
792 // Assume that we know insertion positions for the replacement arguments from replaced
793 // arguments, which is true for all supported targets.
794 assert
!(pre_objects_static
.is_empty() || !pre_objects_static_pie
.is_empty());
795 assert
!(post_objects_static
.is_empty() || !post_objects_static_pie
.is_empty());
796 for arg
in cmd
.take_args() {
797 if arg
.to_string_lossy() == "-static-pie" {
798 // Replace the output kind.
800 } else if pre_objects_static_pie
.contains(&arg
) {
801 // Replace the pre-link objects (replace the first and remove the rest).
802 cmd
.args(mem
::take(&mut pre_objects_static
));
803 } else if post_objects_static_pie
.contains(&arg
) {
804 // Replace the post-link objects (replace the first and remove the rest).
805 cmd
.args(mem
::take(&mut post_objects_static
));
814 // Here's a terribly awful hack that really shouldn't be present in any
815 // compiler. Here an environment variable is supported to automatically
816 // retry the linker invocation if the linker looks like it segfaulted.
818 // Gee that seems odd, normally segfaults are things we want to know
819 // about! Unfortunately though in rust-lang/rust#38878 we're
820 // experiencing the linker segfaulting on Travis quite a bit which is
821 // causing quite a bit of pain to land PRs when they spuriously fail
822 // due to a segfault.
824 // The issue #38878 has some more debugging information on it as well,
825 // but this unfortunately looks like it's just a race condition in
826 // macOS's linker with some thread pool working in the background. It
827 // seems that no one currently knows a fix for this so in the meantime
828 // we're left with this...
829 if !retry_on_segfault
|| i
> 3 {
832 let msg_segv
= "clang: error: unable to execute command: Segmentation fault: 11";
833 let msg_bus
= "clang: error: unable to execute command: Bus error: 10";
834 if out
.contains(msg_segv
) || out
.contains(msg_bus
) {
837 "looks like the linker segfaulted when we tried to call it, \
838 automatically retrying again",
843 if is_illegal_instruction(&output
.status
) {
845 ?cmd
, %out
, status
= %output
.status
,
846 "looks like the linker hit an illegal instruction when we \
847 tried to call it, automatically retrying again.",
853 fn is_illegal_instruction(status
: &ExitStatus
) -> bool
{
854 use std
::os
::unix
::prelude
::*;
855 status
.signal() == Some(libc
::SIGILL
)
859 fn is_illegal_instruction(_status
: &ExitStatus
) -> bool
{
866 if !prog
.status
.success() {
867 let mut output
= prog
.stderr
.clone();
868 output
.extend_from_slice(&prog
.stdout
);
869 let escaped_output
= escape_stdout_stderr_string(&output
);
870 let mut err
= sess
.struct_err(&format
!(
871 "linking with `{}` failed: {}",
872 linker_path
.display(),
875 err
.note(&format
!("{:?}", &cmd
)).note(&escaped_output
);
876 if escaped_output
.contains("undefined reference to") {
878 "some `extern` functions couldn't be found; some native libraries may \
879 need to be installed or have their path specified",
881 err
.note("use the `-l` flag to specify native libraries to link");
882 err
.note("use the `cargo:rustc-link-lib` directive to specify the native \
883 libraries to link with Cargo (see https://doc.rust-lang.org/cargo/reference/build-scripts.html#cargorustc-link-libkindname)");
887 // If MSVC's `link.exe` was expected but the return code
888 // is not a Microsoft LNK error then suggest a way to fix or
889 // install the Visual Studio build tools.
890 if let Some(code
) = prog
.status
.code() {
891 if sess
.target
.is_like_msvc
892 && flavor
== LinkerFlavor
::Msvc
893 // Respect the command line override
894 && sess
.opts
.cg
.linker
.is_none()
895 // Match exactly "link.exe"
896 && linker_path
.to_str() == Some("link.exe")
897 // All Microsoft `link.exe` linking error codes are
898 // four digit numbers in the range 1000 to 9999 inclusive
899 && (code
< 1000 || code
> 9999)
901 let is_vs_installed
= windows_registry
::find_vs_version().is_ok();
902 let has_linker
= windows_registry
::find_tool(
903 &sess
.opts
.target_triple
.triple(),
908 sess
.note_without_error("`link.exe` returned an unexpected error");
909 if is_vs_installed
&& has_linker
{
910 // the linker is broken
911 sess
.note_without_error(
912 "the Visual Studio build tools may need to be repaired \
913 using the Visual Studio installer",
915 sess
.note_without_error(
916 "or a necessary component may be missing from the \
917 \"C++ build tools\" workload",
919 } else if is_vs_installed
{
920 // the linker is not installed
921 sess
.note_without_error(
922 "in the Visual Studio installer, ensure the \
923 \"C++ build tools\" workload is selected",
926 // visual studio is not installed
927 sess
.note_without_error(
928 "you may need to install Visual Studio build tools with the \
929 \"C++ build tools\" workload",
935 sess
.abort_if_errors();
937 info
!("linker stderr:\n{}", escape_stdout_stderr_string(&prog
.stderr
));
938 info
!("linker stdout:\n{}", escape_stdout_stderr_string(&prog
.stdout
));
941 let linker_not_found
= e
.kind() == io
::ErrorKind
::NotFound
;
943 let mut linker_error
= {
944 if linker_not_found
{
945 sess
.struct_err(&format
!("linker `{}` not found", linker_path
.display()))
947 sess
.struct_err(&format
!(
948 "could not exec the linker `{}`",
949 linker_path
.display()
954 linker_error
.note(&e
.to_string());
956 if !linker_not_found
{
957 linker_error
.note(&format
!("{:?}", &cmd
));
962 if sess
.target
.is_like_msvc
&& linker_not_found
{
963 sess
.note_without_error(
964 "the msvc targets depend on the msvc linker \
965 but `link.exe` was not found",
967 sess
.note_without_error(
968 "please ensure that VS 2013, VS 2015, VS 2017, VS 2019 or VS 2022 \
969 was installed with the Visual C++ option",
972 sess
.abort_if_errors();
976 match sess
.split_debuginfo() {
977 // If split debug information is disabled or located in individual files
978 // there's nothing to do here.
979 SplitDebuginfo
::Off
| SplitDebuginfo
::Unpacked
=> {}
981 // If packed split-debuginfo is requested, but the final compilation
982 // doesn't actually have any debug information, then we skip this step.
983 SplitDebuginfo
::Packed
if sess
.opts
.debuginfo
== DebugInfo
::None
=> {}
985 // On macOS the external `dsymutil` tool is used to create the packed
986 // debug information. Note that this will read debug information from
987 // the objects on the filesystem which we'll clean up later.
988 SplitDebuginfo
::Packed
if sess
.target
.is_like_osx
=> {
989 let prog
= Command
::new("dsymutil").arg(out_filename
).output();
992 if !prog
.status
.success() {
993 let mut output
= prog
.stderr
.clone();
994 output
.extend_from_slice(&prog
.stdout
);
995 sess
.struct_warn(&format
!(
996 "processing debug info with `dsymutil` failed: {}",
999 .note(&escape_string(&output
))
1003 Err(e
) => sess
.fatal(&format
!("unable to run `dsymutil`: {}", e
)),
1007 // On MSVC packed debug information is produced by the linker itself so
1008 // there's no need to do anything else here.
1009 SplitDebuginfo
::Packed
if sess
.target
.is_like_windows
=> {}
1011 // ... and otherwise we're processing a `*.dwp` packed dwarf file.
1013 // We cannot rely on the .o paths in the executable because they may have been
1014 // remapped by --remap-path-prefix and therefore invalid, so we need to provide
1015 // the .o/.dwo paths explicitly.
1016 SplitDebuginfo
::Packed
=> link_dwarf_object(sess
, codegen_results
, out_filename
),
1019 let strip
= strip_value(sess
);
1021 if sess
.target
.is_like_osx
{
1022 match (strip
, crate_type
) {
1023 (Strip
::Debuginfo
, _
) => strip_symbols_in_osx(sess
, &out_filename
, Some("-S")),
1024 // Per the manpage, `-x` is the maximum safe strip level for dynamic libraries. (#93988)
1025 (Strip
::Symbols
, CrateType
::Dylib
| CrateType
::Cdylib
| CrateType
::ProcMacro
) => {
1026 strip_symbols_in_osx(sess
, &out_filename
, Some("-x"))
1028 (Strip
::Symbols
, _
) => strip_symbols_in_osx(sess
, &out_filename
, None
),
1029 (Strip
::None
, _
) => {}
1036 // Temporarily support both -Z strip and -C strip
1037 fn strip_value(sess
: &Session
) -> Strip
{
1038 match (sess
.opts
.unstable_opts
.strip
, sess
.opts
.cg
.strip
) {
1039 (s
, Strip
::None
) => s
,
1044 fn strip_symbols_in_osx
<'a
>(sess
: &'a Session
, out_filename
: &Path
, option
: Option
<&str>) {
1045 let mut cmd
= Command
::new("strip");
1046 if let Some(option
) = option
{
1049 let prog
= cmd
.arg(out_filename
).output();
1052 if !prog
.status
.success() {
1053 let mut output
= prog
.stderr
.clone();
1054 output
.extend_from_slice(&prog
.stdout
);
1055 sess
.struct_warn(&format
!(
1056 "stripping debug info with `strip` failed: {}",
1059 .note(&escape_string(&output
))
1063 Err(e
) => sess
.fatal(&format
!("unable to run `strip`: {}", e
)),
1067 fn escape_string(s
: &[u8]) -> String
{
1068 str::from_utf8(s
).map(|s
| s
.to_owned()).unwrap_or_else(|_
| {
1069 let mut x
= "Non-UTF-8 output: ".to_string();
1070 x
.extend(s
.iter().flat_map(|&b
| ascii
::escape_default(b
)).map(char::from
));
1075 fn add_sanitizer_libraries(sess
: &Session
, crate_type
: CrateType
, linker
: &mut dyn Linker
) {
1076 // On macOS the runtimes are distributed as dylibs which should be linked to
1077 // both executables and dynamic shared objects. Everywhere else the runtimes
1078 // are currently distributed as static libraries which should be linked to
1079 // executables only.
1080 let needs_runtime
= match crate_type
{
1081 CrateType
::Executable
=> true,
1082 CrateType
::Dylib
| CrateType
::Cdylib
| CrateType
::ProcMacro
=> sess
.target
.is_like_osx
,
1083 CrateType
::Rlib
| CrateType
::Staticlib
=> false,
1090 let sanitizer
= sess
.opts
.unstable_opts
.sanitizer
;
1091 if sanitizer
.contains(SanitizerSet
::ADDRESS
) {
1092 link_sanitizer_runtime(sess
, linker
, "asan");
1094 if sanitizer
.contains(SanitizerSet
::LEAK
) {
1095 link_sanitizer_runtime(sess
, linker
, "lsan");
1097 if sanitizer
.contains(SanitizerSet
::MEMORY
) {
1098 link_sanitizer_runtime(sess
, linker
, "msan");
1100 if sanitizer
.contains(SanitizerSet
::THREAD
) {
1101 link_sanitizer_runtime(sess
, linker
, "tsan");
1103 if sanitizer
.contains(SanitizerSet
::HWADDRESS
) {
1104 link_sanitizer_runtime(sess
, linker
, "hwasan");
1108 fn link_sanitizer_runtime(sess
: &Session
, linker
: &mut dyn Linker
, name
: &str) {
1109 fn find_sanitizer_runtime(sess
: &Session
, filename
: &str) -> PathBuf
{
1111 filesearch
::make_target_lib_path(&sess
.sysroot
, sess
.opts
.target_triple
.triple());
1112 let path
= session_tlib
.join(filename
);
1114 return session_tlib
;
1116 let default_sysroot
= filesearch
::get_or_default_sysroot();
1117 let default_tlib
= filesearch
::make_target_lib_path(
1119 sess
.opts
.target_triple
.triple(),
1121 return default_tlib
;
1125 let channel
= option_env
!("CFG_RELEASE_CHANNEL")
1126 .map(|channel
| format
!("-{}", channel
))
1127 .unwrap_or_default();
1129 if sess
.target
.is_like_osx
{
1130 // On Apple platforms, the sanitizer is always built as a dylib, and
1131 // LLVM will link to `@rpath/*.dylib`, so we need to specify an
1132 // rpath to the library as well (the rpath should be absolute, see
1133 // PR #41352 for details).
1134 let filename
= format
!("rustc{}_rt.{}", channel
, name
);
1135 let path
= find_sanitizer_runtime(&sess
, &filename
);
1136 let rpath
= path
.to_str().expect("non-utf8 component in path");
1137 linker
.args(&["-Wl,-rpath", "-Xlinker", rpath
]);
1138 linker
.link_dylib(&filename
, false, true);
1140 let filename
= format
!("librustc{}_rt.{}.a", channel
, name
);
1141 let path
= find_sanitizer_runtime(&sess
, &filename
).join(&filename
);
1142 linker
.link_whole_rlib(&path
);
1146 /// Returns a boolean indicating whether the specified crate should be ignored
1149 /// Crates ignored during LTO are not lumped together in the "massive object
1150 /// file" that we create and are linked in their normal rlib states. See
1151 /// comments below for what crates do not participate in LTO.
1153 /// It's unusual for a crate to not participate in LTO. Typically only
1154 /// compiler-specific and unstable crates have a reason to not participate in
1156 pub fn ignored_for_lto(sess
: &Session
, info
: &CrateInfo
, cnum
: CrateNum
) -> bool
{
1157 // If our target enables builtin function lowering in LLVM then the
1158 // crates providing these functions don't participate in LTO (e.g.
1159 // no_builtins or compiler builtins crates).
1160 !sess
.target
.no_builtins
1161 && (info
.compiler_builtins
== Some(cnum
) || info
.is_no_builtins
.contains(&cnum
))
1164 // This functions tries to determine the appropriate linker (and corresponding LinkerFlavor) to use
1165 pub fn linker_and_flavor(sess
: &Session
) -> (PathBuf
, LinkerFlavor
) {
1168 linker
: Option
<PathBuf
>,
1169 flavor
: Option
<LinkerFlavor
>,
1170 ) -> Option
<(PathBuf
, LinkerFlavor
)> {
1171 match (linker
, flavor
) {
1172 (Some(linker
), Some(flavor
)) => Some((linker
, flavor
)),
1173 // only the linker flavor is known; use the default linker for the selected flavor
1174 (None
, Some(flavor
)) => Some((
1175 PathBuf
::from(match flavor
{
1176 LinkerFlavor
::Em
=> {
1183 LinkerFlavor
::Gcc
=> {
1184 if cfg
!(any(target_os
= "solaris", target_os
= "illumos")) {
1185 // On historical Solaris systems, "cc" may have
1186 // been Sun Studio, which is not flag-compatible
1187 // with "gcc". This history casts a long shadow,
1188 // and many modern illumos distributions today
1189 // ship GCC as "gcc" without also making it
1190 // available as "cc".
1196 LinkerFlavor
::Ld
=> "ld",
1197 LinkerFlavor
::Msvc
=> "link.exe",
1198 LinkerFlavor
::Lld(_
) => "lld",
1199 LinkerFlavor
::PtxLinker
=> "rust-ptx-linker",
1200 LinkerFlavor
::BpfLinker
=> "bpf-linker",
1201 LinkerFlavor
::L4Bender
=> "l4-bender",
1205 (Some(linker
), None
) => {
1206 let stem
= linker
.file_stem().and_then(|stem
| stem
.to_str()).unwrap_or_else(|| {
1207 sess
.fatal("couldn't extract file stem from specified linker")
1210 let flavor
= if stem
== "emcc" {
1212 } else if stem
== "gcc"
1213 || stem
.ends_with("-gcc")
1215 || stem
.ends_with("-clang")
1218 } else if stem
== "wasm-ld" || stem
.ends_with("-wasm-ld") {
1219 LinkerFlavor
::Lld(LldFlavor
::Wasm
)
1220 } else if stem
== "ld" || stem
== "ld.lld" || stem
.ends_with("-ld") {
1222 } else if stem
== "link" || stem
== "lld-link" {
1224 } else if stem
== "lld" || stem
== "rust-lld" {
1225 LinkerFlavor
::Lld(sess
.target
.lld_flavor
)
1227 // fall back to the value in the target spec
1228 sess
.target
.linker_flavor
1231 Some((linker
, flavor
))
1233 (None
, None
) => None
,
1237 // linker and linker flavor specified via command line have precedence over what the target
1238 // specification specifies
1239 if let Some(ret
) = infer_from(sess
, sess
.opts
.cg
.linker
.clone(), sess
.opts
.cg
.linker_flavor
) {
1243 if let Some(ret
) = infer_from(
1245 sess
.target
.linker
.as_deref().map(PathBuf
::from
),
1246 Some(sess
.target
.linker_flavor
),
1251 bug
!("Not enough information provided to determine how to invoke the linker");
1254 /// Returns a pair of boolean indicating whether we should preserve the object and
1255 /// dwarf object files on the filesystem for their debug information. This is often
1256 /// useful with split-dwarf like schemes.
1257 fn preserve_objects_for_their_debuginfo(sess
: &Session
) -> (bool
, bool
) {
1258 // If the objects don't have debuginfo there's nothing to preserve.
1259 if sess
.opts
.debuginfo
== config
::DebugInfo
::None
{
1260 return (false, false);
1263 // If we're only producing artifacts that are archives, no need to preserve
1264 // the objects as they're losslessly contained inside the archives.
1265 if sess
.crate_types().iter().all(|&x
| x
.is_archive()) {
1266 return (false, false);
1269 match (sess
.split_debuginfo(), sess
.opts
.unstable_opts
.split_dwarf_kind
) {
1270 // If there is no split debuginfo then do not preserve objects.
1271 (SplitDebuginfo
::Off
, _
) => (false, false),
1272 // If there is packed split debuginfo, then the debuginfo in the objects
1273 // has been packaged and the objects can be deleted.
1274 (SplitDebuginfo
::Packed
, _
) => (false, false),
1275 // If there is unpacked split debuginfo and the current target can not use
1276 // split dwarf, then keep objects.
1277 (SplitDebuginfo
::Unpacked
, _
) if !sess
.target_can_use_split_dwarf() => (true, false),
1278 // If there is unpacked split debuginfo and the target can use split dwarf, then
1279 // keep the object containing that debuginfo (whether that is an object file or
1280 // dwarf object file depends on the split dwarf kind).
1281 (SplitDebuginfo
::Unpacked
, SplitDwarfKind
::Single
) => (true, false),
1282 (SplitDebuginfo
::Unpacked
, SplitDwarfKind
::Split
) => (false, true),
1286 fn archive_search_paths(sess
: &Session
) -> Vec
<PathBuf
> {
1287 sess
.target_filesearch(PathKind
::Native
).search_path_dirs()
1290 #[derive(PartialEq)]
1296 fn print_native_static_libs(sess
: &Session
, all_native_libs
: &[NativeLib
]) {
1297 let lib_args
: Vec
<_
> = all_native_libs
1299 .filter(|l
| relevant_lib(sess
, l
))
1301 let name
= lib
.name?
;
1303 NativeLibKind
::Static { bundle: Some(false), .. }
1304 | NativeLibKind
::Dylib { .. }
1305 | NativeLibKind
::Unspecified
=> {
1306 let verbatim
= lib
.verbatim
.unwrap_or(false);
1307 if sess
.target
.is_like_msvc
{
1308 Some(format
!("{}{}", name
, if verbatim { "" }
else { ".lib" }
))
1309 } else if sess
.target
.linker_is_gnu
{
1310 Some(format
!("-l{}{}", if verbatim { ":" }
else { "" }
, name
))
1312 Some(format
!("-l{}", name
))
1315 NativeLibKind
::Framework { .. }
=> {
1316 // ld-only syntax, since there are no frameworks in MSVC
1317 Some(format
!("-framework {}", name
))
1319 // These are included, no need to print them
1320 NativeLibKind
::Static { bundle: None | Some(true), .. }
1321 | NativeLibKind
::LinkArg
1322 | NativeLibKind
::RawDylib
=> None
,
1326 if !lib_args
.is_empty() {
1327 sess
.note_without_error(
1328 "Link against the following native artifacts when linking \
1329 against this static library. The order and any duplication \
1330 can be significant on some platforms.",
1332 // Prefix for greppability
1333 sess
.note_without_error(&format
!("native-static-libs: {}", &lib_args
.join(" ")));
1337 fn get_object_file_path(sess
: &Session
, name
: &str, self_contained
: bool
) -> PathBuf
{
1338 let fs
= sess
.target_filesearch(PathKind
::Native
);
1339 let file_path
= fs
.get_lib_path().join(name
);
1340 if file_path
.exists() {
1343 // Special directory with objects used only in self-contained linkage mode
1345 let file_path
= fs
.get_self_contained_lib_path().join(name
);
1346 if file_path
.exists() {
1350 for search_path
in fs
.search_paths() {
1351 let file_path
= search_path
.dir
.join(name
);
1352 if file_path
.exists() {
1362 out_filename
: &Path
,
1364 ) -> io
::Result
<Output
> {
1365 // When attempting to spawn the linker we run a risk of blowing out the
1366 // size limits for spawning a new process with respect to the arguments
1367 // we pass on the command line.
1369 // Here we attempt to handle errors from the OS saying "your list of
1370 // arguments is too big" by reinvoking the linker again with an `@`-file
1371 // that contains all the arguments. The theory is that this is then
1372 // accepted on all linkers and the linker will read all its options out of
1373 // there instead of looking at the command line.
1374 if !cmd
.very_likely_to_exceed_some_spawn_limit() {
1375 match cmd
.command().stdout(Stdio
::piped()).stderr(Stdio
::piped()).spawn() {
1377 let output
= child
.wait_with_output();
1378 flush_linked_file(&output
, out_filename
)?
;
1381 Err(ref e
) if command_line_too_big(e
) => {
1382 info
!("command line to linker was too big: {}", e
);
1384 Err(e
) => return Err(e
),
1388 info
!("falling back to passing arguments to linker via an @-file");
1389 let mut cmd2
= cmd
.clone();
1390 let mut args
= String
::new();
1391 for arg
in cmd2
.take_args() {
1393 &Escape { arg: arg.to_str().unwrap(), is_like_msvc: sess.target.is_like_msvc }
1398 let file
= tmpdir
.join("linker-arguments");
1399 let bytes
= if sess
.target
.is_like_msvc
{
1400 let mut out
= Vec
::with_capacity((1 + args
.len()) * 2);
1401 // start the stream with a UTF-16 BOM
1402 for c
in std
::iter
::once(0xFEFF).chain(args
.encode_utf16()) {
1403 // encode in little endian
1405 out
.push((c
>> 8) as u8);
1411 fs
::write(&file
, &bytes
)?
;
1412 cmd2
.arg(format
!("@{}", file
.display()));
1413 info
!("invoking linker {:?}", cmd2
);
1414 let output
= cmd2
.output();
1415 flush_linked_file(&output
, out_filename
)?
;
1418 #[cfg(not(windows))]
1419 fn flush_linked_file(_
: &io
::Result
<Output
>, _
: &Path
) -> io
::Result
<()> {
1424 fn flush_linked_file(
1425 command_output
: &io
::Result
<Output
>,
1426 out_filename
: &Path
,
1427 ) -> io
::Result
<()> {
1428 // On Windows, under high I/O load, output buffers are sometimes not flushed,
1429 // even long after process exit, causing nasty, non-reproducible output bugs.
1431 // File::sync_all() calls FlushFileBuffers() down the line, which solves the problem.
1433 // А full writeup of the original Chrome bug can be found at
1434 // randomascii.wordpress.com/2018/02/25/compiler-bug-linker-bug-windows-kernel-bug/amp
1436 if let &Ok(ref out
) = command_output
{
1437 if out
.status
.success() {
1438 if let Ok(of
) = fs
::OpenOptions
::new().write(true).open(out_filename
) {
1448 fn command_line_too_big(err
: &io
::Error
) -> bool
{
1449 err
.raw_os_error() == Some(::libc
::E2BIG
)
1453 fn command_line_too_big(err
: &io
::Error
) -> bool
{
1454 const ERROR_FILENAME_EXCED_RANGE
: i32 = 206;
1455 err
.raw_os_error() == Some(ERROR_FILENAME_EXCED_RANGE
)
1458 #[cfg(not(any(unix, windows)))]
1459 fn command_line_too_big(_
: &io
::Error
) -> bool
{
1468 impl<'a
> fmt
::Display
for Escape
<'a
> {
1469 fn fmt(&self, f
: &mut fmt
::Formatter
<'_
>) -> fmt
::Result
{
1470 if self.is_like_msvc
{
1471 // This is "documented" at
1472 // https://docs.microsoft.com/en-us/cpp/build/reference/at-specify-a-linker-response-file
1474 // Unfortunately there's not a great specification of the
1475 // syntax I could find online (at least) but some local
1476 // testing showed that this seemed sufficient-ish to catch
1477 // at least a few edge cases.
1479 for c
in self.arg
.chars() {
1481 '
"' => write!(f, "\\{}
", c)?,
1482 c => write!(f, "{}
", c)?,
1487 // This is documented at https://linux.die.net/man/1/ld, namely:
1489 // > Options in file are separated by whitespace. A whitespace
1490 // > character may be included in an option by surrounding the
1491 // > entire option in either single or double quotes. Any
1492 // > character (including a backslash) may be included by
1493 // > prefixing the character to be included with a backslash.
1495 // We put an argument on each line, so all we need to do is
1496 // ensure the line is interpreted as one whole argument.
1497 for c in self.arg.chars() {
1499 '\\' | ' ' => write!(f, "\\{}
", c)?,
1500 c => write!(f, "{}
", c)?,
1509 fn link_output_kind(sess: &Session, crate_type: CrateType) -> LinkOutputKind {
1510 let kind = match (crate_type, sess.crt_static(Some(crate_type)), sess.relocation_model()) {
1511 (CrateType::Executable, _, _) if sess.is_wasi_reactor() => LinkOutputKind::WasiReactorExe,
1512 (CrateType::Executable, false, RelocModel::Pic | RelocModel::Pie) => {
1513 LinkOutputKind::DynamicPicExe
1515 (CrateType::Executable, false, _) => LinkOutputKind::DynamicNoPicExe,
1516 (CrateType::Executable, true, RelocModel::Pic | RelocModel::Pie) => {
1517 LinkOutputKind::StaticPicExe
1519 (CrateType::Executable, true, _) => LinkOutputKind::StaticNoPicExe,
1520 (_, true, _) => LinkOutputKind::StaticDylib,
1521 (_, false, _) => LinkOutputKind::DynamicDylib,
1524 // Adjust the output kind to target capabilities.
1525 let opts = &sess.target;
1526 let pic_exe_supported = opts.position_independent_executables;
1527 let static_pic_exe_supported = opts.static_position_independent_executables;
1528 let static_dylib_supported = opts.crt_static_allows_dylibs;
1530 LinkOutputKind::DynamicPicExe if !pic_exe_supported => LinkOutputKind::DynamicNoPicExe,
1531 LinkOutputKind::StaticPicExe if !static_pic_exe_supported => LinkOutputKind::StaticNoPicExe,
1532 LinkOutputKind::StaticDylib if !static_dylib_supported => LinkOutputKind::DynamicDylib,
1537 // Returns true if linker is located within sysroot
1538 fn detect_self_contained_mingw(sess: &Session) -> bool {
1539 let (linker, _) = linker_and_flavor(&sess);
1540 // Assume `-C linker=rust-lld` as self-contained mode
1541 if linker == Path::new("rust
-lld
") {
1544 let linker_with_extension = if cfg!(windows) && linker.extension().is_none() {
1545 linker.with_extension("exe
")
1549 for dir in env::split_paths(&env::var_os("PATH
").unwrap_or_default()) {
1550 let full_path = dir.join(&linker_with_extension);
1551 // If linker comes from sysroot assume self-contained mode
1552 if full_path.is_file() && !full_path.starts_with(&sess.sysroot) {
1559 /// Whether we link to our own CRT objects instead of relying on gcc to pull them.
1560 /// We only provide such support for a very limited number of targets.
1561 fn crt_objects_fallback(sess: &Session, crate_type: CrateType) -> bool {
1562 if let Some(self_contained) = sess.opts.cg.link_self_contained {
1563 return self_contained;
1566 match sess.target.crt_objects_fallback {
1567 // FIXME: Find a better heuristic for "native musl toolchain is available
",
1568 // based on host and linker path, for example.
1569 // (https://github.com/rust-lang/rust/pull/71769#issuecomment-626330237).
1570 Some(CrtObjectsFallback::Musl) => sess.crt_static(Some(crate_type)),
1571 Some(CrtObjectsFallback::Mingw) => {
1572 sess.host == sess.target
1573 && sess.target.vendor != "uwp
"
1574 && detect_self_contained_mingw(&sess)
1576 // FIXME: Figure out cases in which WASM needs to link with a native toolchain.
1577 Some(CrtObjectsFallback::Wasm) => true,
1582 /// Add pre-link object files defined by the target spec.
1583 fn add_pre_link_objects(
1584 cmd: &mut dyn Linker,
1586 link_output_kind: LinkOutputKind,
1587 self_contained: bool,
1589 let opts = &sess.target;
1591 if self_contained { &opts.pre_link_objects_fallback } else { &opts.pre_link_objects };
1592 for obj in objects.get(&link_output_kind).iter().copied().flatten() {
1593 cmd.add_object(&get_object_file_path(sess, obj, self_contained));
1597 /// Add post-link object files defined by the target spec.
1598 fn add_post_link_objects(
1599 cmd: &mut dyn Linker,
1601 link_output_kind: LinkOutputKind,
1602 self_contained: bool,
1604 let opts = &sess.target;
1606 if self_contained { &opts.post_link_objects_fallback } else { &opts.post_link_objects };
1607 for obj in objects.get(&link_output_kind).iter().copied().flatten() {
1608 cmd.add_object(&get_object_file_path(sess, obj, self_contained));
1612 /// Add arbitrary "pre
-link
" args defined by the target spec or from command line.
1613 /// FIXME: Determine where exactly these args need to be inserted.
1614 fn add_pre_link_args(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavor) {
1615 if let Some(args) = sess.target.pre_link_args.get(&flavor) {
1616 cmd.args(args.iter().map(Deref::deref));
1618 cmd.args(&sess.opts.unstable_opts.pre_link_args);
1621 /// Add a link script embedded in the target, if applicable.
1622 fn add_link_script(cmd: &mut dyn Linker, sess: &Session, tmpdir: &Path, crate_type: CrateType) {
1623 match (crate_type, &sess.target.link_script) {
1624 (CrateType::Cdylib | CrateType::Executable, Some(script)) => {
1625 if !sess.target.linker_is_gnu {
1626 sess.fatal("can only
use link script when linking with GNU
-like linker
");
1629 let file_name = ["rustc
", &sess.target.llvm_target, "linkfile
.ld
"].join("-");
1631 let path = tmpdir.join(file_name);
1632 if let Err(e) = fs::write(&path, script.as_ref()) {
1633 sess.fatal(&format!("failed to write link script to {}
: {}
", path.display(), e));
1636 cmd.arg("--script
");
1643 /// Add arbitrary "user defined
" args defined from command line.
1644 /// FIXME: Determine where exactly these args need to be inserted.
1645 fn add_user_defined_link_args(cmd: &mut dyn Linker, sess: &Session) {
1646 cmd.args(&sess.opts.cg.link_args);
1649 /// Add arbitrary "late link
" args defined by the target spec.
1650 /// FIXME: Determine where exactly these args need to be inserted.
1651 fn add_late_link_args(
1652 cmd: &mut dyn Linker,
1654 flavor: LinkerFlavor,
1655 crate_type: CrateType,
1656 codegen_results: &CodegenResults,
1658 let any_dynamic_crate = crate_type == CrateType::Dylib
1659 || codegen_results.crate_info.dependency_formats.iter().any(|(ty, list)| {
1660 *ty == crate_type && list.iter().any(|&linkage| linkage == Linkage::Dynamic)
1662 if any_dynamic_crate {
1663 if let Some(args) = sess.target.late_link_args_dynamic.get(&flavor) {
1664 cmd.args(args.iter().map(Deref::deref));
1667 if let Some(args) = sess.target.late_link_args_static.get(&flavor) {
1668 cmd.args(args.iter().map(Deref::deref));
1671 if let Some(args) = sess.target.late_link_args.get(&flavor) {
1672 cmd.args(args.iter().map(Deref::deref));
1676 /// Add arbitrary "post
-link
" args defined by the target spec.
1677 /// FIXME: Determine where exactly these args need to be inserted.
1678 fn add_post_link_args(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavor) {
1679 if let Some(args) = sess.target.post_link_args.get(&flavor) {
1680 cmd.args(args.iter().map(Deref::deref));
1684 /// Add a synthetic object file that contains reference to all symbols that we want to expose to
1687 /// Background: we implement rlibs as static library (archives). Linkers treat archives
1688 /// differently from object files: all object files participate in linking, while archives will
1689 /// only participate in linking if they can satisfy at least one undefined reference (version
1690 /// scripts doesn't count). This causes `#[no_mangle]` or `#[used]` items to be ignored by the
1691 /// linker, and since they never participate in the linking, using `KEEP` in the linker scripts
1692 /// can't keep them either. This causes #47384.
1694 /// To keep them around, we could use `--whole-archive` and equivalents to force rlib to
1695 /// participate in linking like object files, but this proves to be expensive (#93791). Therefore
1696 /// we instead just introduce an undefined reference to them. This could be done by `-u` command
1697 /// line option to the linker or `EXTERN(...)` in linker scripts, however they does not only
1698 /// introduce an undefined reference, but also make them the GC roots, preventing `--gc-sections`
1699 /// from removing them, and this is especially problematic for embedded programming where every
1702 /// This method creates a synthetic object file, which contains undefined references to all symbols
1703 /// that are necessary for the linking. They are only present in symbol table but not actually
1704 /// used in any sections, so the linker will therefore pick relevant rlibs for linking, but
1705 /// unused `#[no_mangle]` or `#[used]` can still be discard by GC sections.
1706 fn add_linked_symbol_object(
1707 cmd: &mut dyn Linker,
1710 symbols: &[(String, SymbolExportKind)],
1712 if symbols.is_empty() {
1716 let Some(mut file) = super::metadata::create_object_file(sess) else {
1720 // NOTE(nbdd0121): MSVC will hang if the input object file contains no sections,
1721 // so add an empty section.
1722 if file.format() == object::BinaryFormat::Coff {
1723 file.add_section(Vec::new(), ".text
".into(), object::SectionKind::Text);
1725 // We handle the name decoration of COFF targets in `symbol_export.rs`, so disable the
1726 // default mangler in `object` crate.
1727 file.set_mangling(object::write::Mangling::None);
1729 // Add feature flags to the object file. On MSVC this is optional but LLD will complain if
1731 let mut feature = 0;
1733 if file.architecture() == object::Architecture::I386 {
1734 // Indicate that all SEH handlers are registered in .sxdata section.
1735 // We don't have generate any code, so we don't need .sxdata section but LLD still
1736 // expects us to set this bit (see #96498).
1737 // Reference: https://docs.microsoft.com/en-us/windows/win32/debug/pe-format
1741 file.add_symbol(object::write::Symbol {
1742 name: "@feat
.00".into(),
1745 kind: object::SymbolKind::Data,
1746 scope: object::SymbolScope::Compilation,
1748 section: object::write::SymbolSection::Absolute,
1749 flags: object::SymbolFlags::None,
1753 for (sym, kind) in symbols.iter() {
1754 file.add_symbol(object::write::Symbol {
1755 name: sym.clone().into(),
1759 SymbolExportKind::Text => object::SymbolKind::Text,
1760 SymbolExportKind::Data => object::SymbolKind::Data,
1761 SymbolExportKind::Tls => object::SymbolKind::Tls,
1763 scope: object::SymbolScope::Unknown,
1765 section: object::write::SymbolSection::Undefined,
1766 flags: object::SymbolFlags::None,
1770 let path = tmpdir.join("symbols
.o
");
1771 let result = std::fs::write(&path, file.write().unwrap());
1772 if let Err(e) = result {
1773 sess.fatal(&format!("failed to write {}
: {}
", path.display(), e));
1775 cmd.add_object(&path);
1778 /// Add object files containing code from the current crate.
1779 fn add_local_crate_regular_objects(cmd: &mut dyn Linker, codegen_results: &CodegenResults) {
1780 for obj in codegen_results.modules.iter().filter_map(|m| m.object.as_ref()) {
1781 cmd.add_object(obj);
1785 /// Add object files for allocator code linked once for the whole crate tree.
1786 fn add_local_crate_allocator_objects(cmd: &mut dyn Linker, codegen_results: &CodegenResults) {
1787 if let Some(obj) = codegen_results.allocator_module.as_ref().and_then(|m| m.object.as_ref()) {
1788 cmd.add_object(obj);
1792 /// Add object files containing metadata for the current crate.
1793 fn add_local_crate_metadata_objects(
1794 cmd: &mut dyn Linker,
1795 crate_type: CrateType,
1796 codegen_results: &CodegenResults,
1798 // When linking a dynamic library, we put the metadata into a section of the
1799 // executable. This metadata is in a separate object file from the main
1800 // object file, so we link that in here.
1801 if crate_type == CrateType::Dylib || crate_type == CrateType::ProcMacro {
1802 if let Some(obj) = codegen_results.metadata_module.as_ref().and_then(|m| m.object.as_ref())
1804 cmd.add_object(obj);
1809 /// Add sysroot and other globally set directories to the directory search list.
1810 fn add_library_search_dirs(cmd: &mut dyn Linker, sess: &Session, self_contained: bool) {
1811 // The default library location, we need this to find the runtime.
1812 // The location of crates will be determined as needed.
1813 let lib_path = sess.target_filesearch(PathKind::All).get_lib_path();
1814 cmd.include_path(&fix_windows_verbatim_for_gcc(&lib_path));
1816 // Special directory with libraries used only in self-contained linkage mode
1818 let lib_path = sess.target_filesearch(PathKind::All).get_self_contained_lib_path();
1819 cmd.include_path(&fix_windows_verbatim_for_gcc(&lib_path));
1823 /// Add options making relocation sections in the produced ELF files read-only
1824 /// and suppressing lazy binding.
1825 fn add_relro_args(cmd: &mut dyn Linker, sess: &Session) {
1826 match sess.opts.unstable_opts.relro_level.unwrap_or(sess.target.relro_level) {
1827 RelroLevel::Full => cmd.full_relro(),
1828 RelroLevel::Partial => cmd.partial_relro(),
1829 RelroLevel::Off => cmd.no_relro(),
1830 RelroLevel::None => {}
1834 /// Add library search paths used at runtime by dynamic linkers.
1836 cmd: &mut dyn Linker,
1838 codegen_results: &CodegenResults,
1839 out_filename: &Path,
1841 // FIXME (#2397): At some point we want to rpath our guesses as to
1842 // where extern libraries might live, based on the
1843 // add_lib_search_paths
1844 if sess.opts.cg.rpath {
1845 let libs = codegen_results
1849 .filter_map(|cnum| {
1850 codegen_results.crate_info.used_crate_source[cnum]
1853 .map(|(path, _)| &**path)
1855 .collect::<Vec<_>>();
1856 let mut rpath_config = RPathConfig {
1858 out_filename: out_filename.to_path_buf(),
1859 has_rpath: sess.target.has_rpath,
1860 is_like_osx: sess.target.is_like_osx,
1861 linker_is_gnu: sess.target.linker_is_gnu,
1863 cmd.args(&rpath::get_rpath_flags(&mut rpath_config));
1867 /// Produce the linker command line containing linker path and arguments.
1869 /// When comments in the function say "order
-(in)dependent
" they mean order-dependence between
1870 /// options and libraries/object files. For example `--whole-archive` (order-dependent) applies
1871 /// to specific libraries passed after it, and `-o` (output file, order-independent) applies
1872 /// to the linking process as a whole.
1873 /// Order-independent options may still override each other in order-dependent fashion,
1874 /// e.g `--foo=yes --foo=no` may be equivalent to `--foo=no`.
1875 fn linker_with_args<'a>(
1877 flavor: LinkerFlavor,
1879 archive_builder_builder: &dyn ArchiveBuilderBuilder,
1880 crate_type: CrateType,
1882 out_filename: &Path,
1883 codegen_results: &CodegenResults,
1884 ) -> Result<Command, ErrorGuaranteed> {
1885 let crt_objects_fallback = crt_objects_fallback(sess, crate_type);
1886 let cmd = &mut *super::linker::get_linker(
1890 crt_objects_fallback,
1891 &codegen_results.crate_info.target_cpu,
1893 let link_output_kind = link_output_kind(sess, crate_type);
1895 // ------------ Early order-dependent options ------------
1897 // If we're building something like a dynamic library then some platforms
1898 // need to make sure that all symbols are exported correctly from the
1900 // Must be passed before any libraries to prevent the symbols to export from being thrown away,
1901 // at least on some platforms (e.g. windows-gnu).
1905 &codegen_results.crate_info.exported_symbols[&crate_type],
1908 // Can be used for adding custom CRT objects or overriding order-dependent options above.
1909 // FIXME: In practice built-in target specs use this for arbitrary order-independent options,
1910 // introduce a target spec option for order-independent linker options and migrate built-in
1912 add_pre_link_args(cmd, sess, flavor);
1914 // ------------ Object code and libraries, order-dependent ------------
1916 // Pre-link CRT objects.
1917 add_pre_link_objects(cmd, sess, link_output_kind, crt_objects_fallback);
1919 add_linked_symbol_object(
1923 &codegen_results.crate_info.linked_symbols[&crate_type],
1926 // Sanitizer libraries.
1927 add_sanitizer_libraries(sess, crate_type, cmd);
1929 // Object code from the current crate.
1930 // Take careful note of the ordering of the arguments we pass to the linker
1931 // here. Linkers will assume that things on the left depend on things to the
1932 // right. Things on the right cannot depend on things on the left. This is
1933 // all formally implemented in terms of resolving symbols (libs on the right
1934 // resolve unknown symbols of libs on the left, but not vice versa).
1936 // For this reason, we have organized the arguments we pass to the linker as
1939 // 1. The local object that LLVM just generated
1940 // 2. Local native libraries
1941 // 3. Upstream rust libraries
1942 // 4. Upstream native libraries
1944 // The rationale behind this ordering is that those items lower down in the
1945 // list can't depend on items higher up in the list. For example nothing can
1946 // depend on what we just generated (e.g., that'd be a circular dependency).
1947 // Upstream rust libraries are not supposed to depend on our local native
1948 // libraries as that would violate the structure of the DAG, in that
1949 // scenario they are required to link to them as well in a shared fashion.
1950 // (The current implementation still doesn't prevent it though, see the FIXME below.)
1952 // Note that upstream rust libraries may contain native dependencies as
1953 // well, but they also can't depend on what we just started to add to the
1954 // link line. And finally upstream native libraries can't depend on anything
1955 // in this DAG so far because they can only depend on other native libraries
1956 // and such dependencies are also required to be specified.
1957 add_local_crate_regular_objects(cmd, codegen_results);
1958 add_local_crate_metadata_objects(cmd, crate_type, codegen_results);
1959 add_local_crate_allocator_objects(cmd, codegen_results);
1961 // Avoid linking to dynamic libraries unless they satisfy some undefined symbols
1962 // at the point at which they are specified on the command line.
1963 // Must be passed before any (dynamic) libraries to have effect on them.
1964 // On Solaris-like systems, `-z ignore` acts as both `--as-needed` and `--gc-sections`
1965 // so it will ignore unreferenced ELF sections from relocatable objects.
1966 // For that reason, we put this flag after metadata objects as they would otherwise be removed.
1967 // FIXME: Support more fine-grained dead code removal on Solaris/illumos
1968 // and move this option back to the top.
1969 cmd.add_as_needed();
1971 // FIXME: Move this below to other native libraries
1972 // (or alternatively link all native libraries after their respective crates).
1973 // This change is somewhat breaking in practice due to local static libraries being linked
1974 // as whole-archive (#85144), so removing whole-archive may be a pre-requisite.
1975 if sess.opts.unstable_opts.link_native_libraries {
1976 add_local_native_libraries(cmd, sess, codegen_results);
1979 // Upstream rust libraries and their non-bundled static libraries
1980 add_upstream_rust_crates(
1983 archive_builder_builder,
1989 // Upstream dynamic native libraries linked with `#[link]` attributes at and `-l`
1990 // command line options.
1991 // If -Zlink-native-libraries=false is set, then the assumption is that an
1992 // external build system already has the native dependencies defined, and it
1993 // will provide them to the linker itself.
1994 if sess.opts.unstable_opts.link_native_libraries {
1995 add_upstream_native_libraries(cmd, sess, codegen_results);
1998 // Link with the import library generated for any raw-dylib functions.
1999 for (raw_dylib_name, raw_dylib_imports) in
2000 collate_raw_dylibs(sess, &codegen_results.crate_info.used_libraries)?
2002 cmd.add_object(&archive_builder_builder.create_dll_import_lib(
2010 // Library linking above uses some global state for things like `-Bstatic`/`-Bdynamic` to make
2011 // command line shorter, reset it to default here before adding more libraries.
2012 cmd.reset_per_library_state();
2014 // FIXME: Built-in target specs occasionally use this for linking system libraries,
2015 // eliminate all such uses by migrating them to `#[link]` attributes in `lib(std,c,unwind)`
2016 // and remove the option.
2017 add_late_link_args(cmd, sess, flavor, crate_type, codegen_results);
2019 // ------------ Arbitrary order-independent options ------------
2021 // Add order-independent options determined by rustc from its compiler options,
2022 // target properties and source code.
2023 add_order_independent_options(
2027 crt_objects_fallback,
2035 // Can be used for arbitrary order-independent options.
2036 // In practice may also be occasionally used for linking native libraries.
2037 // Passed after compiler-generated options to support manual overriding when necessary.
2038 add_user_defined_link_args(cmd, sess);
2040 // ------------ Object code and libraries, order-dependent ------------
2042 // Post-link CRT objects.
2043 add_post_link_objects(cmd, sess, link_output_kind, crt_objects_fallback);
2045 // ------------ Late order-dependent options ------------
2047 // Doesn't really make sense.
2048 // FIXME: In practice built-in target specs use this for arbitrary order-independent options,
2049 // introduce a target spec option for order-independent linker options, migrate built-in specs
2050 // to it and remove the option.
2051 add_post_link_args(cmd, sess, flavor);
2056 fn add_order_independent_options(
2057 cmd: &mut dyn Linker,
2059 link_output_kind: LinkOutputKind,
2060 crt_objects_fallback: bool,
2061 flavor: LinkerFlavor,
2062 crate_type: CrateType,
2063 codegen_results: &CodegenResults,
2064 out_filename: &Path,
2067 add_gcc_ld_path(cmd, sess, flavor);
2069 add_apple_sdk(cmd, sess, flavor);
2071 add_link_script(cmd, sess, tmpdir, crate_type);
2073 if sess.target.os == "fuchsia
" && crate_type == CrateType::Executable {
2074 let prefix = if sess.opts.unstable_opts.sanitizer.contains(SanitizerSet::ADDRESS) {
2079 cmd.arg(format!("--dynamic
-linker
={}ld
.so
.1", prefix));
2082 if sess.target.eh_frame_header {
2083 cmd.add_eh_frame_header();
2086 // Make the binary compatible with data execution prevention schemes.
2089 if crt_objects_fallback {
2090 cmd.no_crt_objects();
2093 if sess.target.os == "emscripten
" {
2095 cmd.arg(if sess.panic_strategy() == PanicStrategy::Abort {
2096 "DISABLE_EXCEPTION_CATCHING
=1"
2098 "DISABLE_EXCEPTION_CATCHING
=0"
2102 if flavor == LinkerFlavor::PtxLinker {
2103 // Provide the linker with fallback to internal `target-cpu`.
2104 cmd.arg("--fallback
-arch
");
2105 cmd.arg(&codegen_results.crate_info.target_cpu);
2106 } else if flavor == LinkerFlavor::BpfLinker {
2108 cmd.arg(&codegen_results.crate_info.target_cpu);
2109 cmd.arg("--cpu
-features
");
2110 cmd.arg(match &sess.opts.cg.target_feature {
2111 feat if !feat.is_empty() => feat.as_ref(),
2112 _ => sess.target.options.features.as_ref(),
2116 cmd.linker_plugin_lto();
2118 add_library_search_dirs(cmd, sess, crt_objects_fallback);
2120 cmd.output_filename(out_filename);
2122 if crate_type == CrateType::Executable && sess.target.is_like_windows {
2123 if let Some(ref s) = codegen_results.crate_info.windows_subsystem {
2128 // Try to strip as much out of the generated object by removing unused
2129 // sections if possible. See more comments in linker.rs
2130 if !sess.link_dead_code() {
2131 // If PGO is enabled sometimes gc_sections will remove the profile data section
2132 // as it appears to be unused. This can then cause the PGO profile file to lose
2133 // some functions. If we are generating a profile we shouldn't strip those metadata
2134 // sections to ensure we have all the data for PGO.
2136 crate_type == CrateType::Dylib || sess.opts.cg.profile_generate.enabled();
2137 if crate_type != CrateType::Executable || !sess.opts.unstable_opts.export_executable_symbols
2139 cmd.gc_sections(keep_metadata);
2141 cmd.no_gc_sections();
2145 cmd.set_output_kind(link_output_kind, out_filename);
2147 add_relro_args(cmd, sess);
2149 // Pass optimization flags down to the linker.
2152 // Gather the set of NatVis files, if any, and write them out to a temp directory.
2153 let natvis_visualizers = collect_natvis_visualizers(
2156 &codegen_results.crate_info.local_crate_name,
2157 &codegen_results.crate_info.natvis_debugger_visualizers,
2160 // Pass debuginfo, NatVis debugger visualizers and strip flags down to the linker.
2161 cmd.debuginfo(strip_value(sess), &natvis_visualizers);
2163 // We want to prevent the compiler from accidentally leaking in any system libraries,
2164 // so by default we tell linkers not to link to any default libraries.
2165 if !sess.opts.cg.default_linker_libraries && sess.target.no_default_libraries {
2166 cmd.no_default_libraries();
2169 if sess.opts.cg.profile_generate.enabled() || sess.instrument_coverage() {
2173 if sess.opts.cg.control_flow_guard != CFGuard::Disabled {
2174 cmd.control_flow_guard();
2177 add_rpath_args(cmd, sess, codegen_results, out_filename);
2180 // Write the NatVis debugger visualizer files for each crate to the temp directory and gather the file paths.
2181 fn collect_natvis_visualizers(
2184 crate_name: &Symbol,
2185 natvis_debugger_visualizers: &BTreeSet<DebuggerVisualizerFile>,
2187 let mut visualizer_paths = Vec::with_capacity(natvis_debugger_visualizers.len());
2189 for (index, visualizer) in natvis_debugger_visualizers.iter().enumerate() {
2190 let visualizer_out_file = tmpdir.join(format!("{}
-{}
.natvis
", crate_name.as_str(), index));
2192 match fs::write(&visualizer_out_file, &visualizer.src) {
2194 visualizer_paths.push(visualizer_out_file);
2199 "Unable to write debugger visualizer file `{}`
: {}
",
2200 visualizer_out_file.display(),
2211 /// # Native library linking
2213 /// User-supplied library search paths (-L on the command line). These are the same paths used to
2214 /// find Rust crates, so some of them may have been added already by the previous crate linking
2215 /// code. This only allows them to be found at compile time so it is still entirely up to outside
2216 /// forces to make sure that library can be found at runtime.
2218 /// Also note that the native libraries linked here are only the ones located in the current crate.
2219 /// Upstream crates with native library dependencies may have their native library pulled in above.
2220 fn add_local_native_libraries(
2221 cmd: &mut dyn Linker,
2223 codegen_results: &CodegenResults,
2225 let filesearch = sess.target_filesearch(PathKind::All);
2226 for search_path in filesearch.search_paths() {
2227 match search_path.kind {
2228 PathKind::Framework => {
2229 cmd.framework_path(&search_path.dir);
2232 cmd.include_path(&fix_windows_verbatim_for_gcc(&search_path.dir));
2238 codegen_results.crate_info.used_libraries.iter().filter(|l| relevant_lib(sess, l));
2240 let search_path = OnceCell::new();
2241 let mut last = (None, NativeLibKind::Unspecified, None);
2242 for lib in relevant_libs {
2243 let Some(name) = lib.name else {
2246 let name = name.as_str();
2248 // Skip if this library is the same as the last.
2249 last = if (lib.name, lib.kind, lib.verbatim) == last {
2252 (lib.name, lib.kind, lib.verbatim)
2255 let verbatim = lib.verbatim.unwrap_or(false);
2257 NativeLibKind::Dylib { as_needed } => {
2258 cmd.link_dylib(name, verbatim, as_needed.unwrap_or(true))
2260 NativeLibKind::Unspecified => cmd.link_dylib(name, verbatim, true),
2261 NativeLibKind::Framework { as_needed } => {
2262 cmd.link_framework(name, as_needed.unwrap_or(true))
2264 NativeLibKind::Static { whole_archive, bundle, .. } => {
2265 if whole_archive == Some(true)
2266 // Backward compatibility case: this can be a rlib (so `+whole-archive` cannot
2267 // be added explicitly if necessary, see the error in `fn link_rlib`) compiled
2268 // as an executable due to `--test`. Use whole-archive implicitly, like before
2269 // the introduction of native lib modifiers.
2270 || (whole_archive == None && bundle != Some(false) && sess.opts.test)
2272 cmd.link_whole_staticlib(
2275 &search_path.get_or_init(|| archive_search_paths(sess)),
2278 cmd.link_staticlib(name, verbatim)
2281 NativeLibKind::RawDylib => {
2282 // Ignore RawDylib here, they are handled separately in linker_with_args().
2284 NativeLibKind::LinkArg => {
2291 /// # Linking Rust crates and their non-bundled static libraries
2293 /// Rust crates are not considered at all when creating an rlib output. All dependencies will be
2294 /// linked when producing the final output (instead of the intermediate rlib version).
2295 fn add_upstream_rust_crates<'a>(
2296 cmd: &mut dyn Linker,
2298 archive_builder_builder: &dyn ArchiveBuilderBuilder,
2299 codegen_results: &CodegenResults,
2300 crate_type: CrateType,
2303 // All of the heavy lifting has previously been accomplished by the
2304 // dependency_format module of the compiler. This is just crawling the
2305 // output of that module, adding crates as necessary.
2307 // Linking to a rlib involves just passing it to the linker (the linker
2308 // will slurp up the object files inside), and linking to a dynamic library
2309 // involves just passing the right -l flag.
2311 let (_, data) = codegen_results
2315 .find(|(ty, _)| *ty == crate_type)
2316 .expect("failed to find
crate type in dependency format list
");
2318 // Invoke get_used_crates to ensure that we get a topological sorting of
2320 let deps = &codegen_results.crate_info.used_crates;
2322 // There's a few internal crates in the standard library (aka libcore and
2323 // libstd) which actually have a circular dependence upon one another. This
2324 // currently arises through "weak lang items
" where libcore requires things
2325 // like `rust_begin_unwind` but libstd ends up defining it. To get this
2326 // circular dependence to work correctly in all situations we'll need to be
2327 // sure to correctly apply the `--start-group` and `--end-group` options to
2328 // GNU linkers, otherwise if we don't use any other symbol from the standard
2329 // library it'll get discarded and the whole application won't link.
2331 // In this loop we're calculating the `group_end`, after which crate to
2332 // pass `--end-group` and `group_start`, before which crate to pass
2333 // `--start-group`. We currently do this by passing `--end-group` after
2334 // the first crate (when iterating backwards) that requires a lang item
2335 // defined somewhere else. Once that's set then when we've defined all the
2336 // necessary lang items we'll pass `--start-group`.
2338 // Note that this isn't amazing logic for now but it should do the trick
2339 // for the current implementation of the standard library.
2340 let mut group_end = None;
2341 let mut group_start = None;
2342 // Crates available for linking thus far.
2343 let mut available = FxHashSet::default();
2344 // Crates required to satisfy dependencies discovered so far.
2345 let mut required = FxHashSet::default();
2347 let info = &codegen_results.crate_info;
2348 for &cnum in deps.iter().rev() {
2349 if let Some(missing) = info.missing_lang_items.get(&cnum) {
2350 let missing_crates = missing.iter().map(|i| info.lang_item_to_crate.get(i).copied());
2351 required.extend(missing_crates);
2354 required.insert(Some(cnum));
2355 available.insert(Some(cnum));
2357 if required.len() > available.len() && group_end.is_none() {
2358 group_end = Some(cnum);
2360 if required.len() == available.len() && group_end.is_some() {
2361 group_start = Some(cnum);
2366 // If we didn't end up filling in all lang items from upstream crates then
2367 // we'll be filling it in with our crate. This probably means we're the
2368 // standard library itself, so skip this for now.
2369 if group_end.is_some() && group_start.is_none() {
2373 let mut compiler_builtins = None;
2374 let search_path = OnceCell::new();
2376 for &cnum in deps.iter() {
2377 if group_start == Some(cnum) {
2381 // We may not pass all crates through to the linker. Some crates may
2382 // appear statically in an existing dylib, meaning we'll pick up all the
2383 // symbols from the dylib.
2384 let src = &codegen_results.crate_info.used_crate_source[&cnum];
2385 match data[cnum.as_usize() - 1] {
2386 _ if codegen_results.crate_info.profiler_runtime == Some(cnum) => {
2387 add_static_crate(cmd, sess, archive_builder_builder, codegen_results, tmpdir, cnum);
2389 // compiler-builtins are always placed last to ensure that they're
2390 // linked correctly.
2391 _ if codegen_results.crate_info.compiler_builtins == Some(cnum) => {
2392 assert!(compiler_builtins.is_none());
2393 compiler_builtins = Some(cnum);
2395 Linkage::NotLinked | Linkage::IncludedFromDylib => {}
2396 Linkage::Static => {
2397 add_static_crate(cmd, sess, archive_builder_builder, codegen_results, tmpdir, cnum);
2399 // Link static native libs with "-bundle
" modifier only if the crate they originate from
2400 // is being linked statically to the current crate. If it's linked dynamically
2401 // or is an rlib already included via some other dylib crate, the symbols from
2402 // native libs will have already been included in that dylib.
2404 // If -Zlink-native-libraries=false is set, then the assumption is that an
2405 // external build system already has the native dependencies defined, and it
2406 // will provide them to the linker itself.
2407 if sess.opts.unstable_opts.link_native_libraries {
2408 let mut last = (None, NativeLibKind::Unspecified, None);
2409 for lib in &codegen_results.crate_info.native_libraries[&cnum] {
2410 let Some(name) = lib.name else {
2413 let name = name.as_str();
2414 if !relevant_lib(sess, lib) {
2418 // Skip if this library is the same as the last.
2419 last = if (lib.name, lib.kind, lib.verbatim) == last {
2422 (lib.name, lib.kind, lib.verbatim)
2426 NativeLibKind::Static {
2427 bundle: Some(false),
2428 whole_archive: Some(true),
2430 cmd.link_whole_staticlib(
2432 lib.verbatim.unwrap_or(false),
2433 search_path.get_or_init(|| archive_search_paths(sess)),
2436 NativeLibKind::Static {
2437 bundle: Some(false),
2438 whole_archive: Some(false) | None,
2440 cmd.link_staticlib(name, lib.verbatim.unwrap_or(false));
2442 NativeLibKind::LinkArg => {
2445 NativeLibKind::Dylib { .. }
2446 | NativeLibKind::Framework { .. }
2447 | NativeLibKind::Unspecified
2448 | NativeLibKind::RawDylib => {}
2449 NativeLibKind::Static {
2450 bundle: Some(true) | None,
2457 Linkage::Dynamic => add_dynamic_crate(cmd, sess, &src.dylib.as_ref().unwrap().0),
2460 if group_end == Some(cnum) {
2465 // compiler-builtins are always placed last to ensure that they're
2466 // linked correctly.
2467 // We must always link the `compiler_builtins` crate statically. Even if it
2468 // was already "included
" in a dylib (e.g., `libstd` when `-C prefer-dynamic`
2470 if let Some(cnum) = compiler_builtins {
2471 add_static_crate(cmd, sess, archive_builder_builder, codegen_results, tmpdir, cnum);
2474 // Converts a library file-stem into a cc -l argument
2475 fn unlib<'a>(target: &Target, stem: &'a str) -> &'a str {
2476 if stem.starts_with("lib
") && !target.is_like_windows { &stem[3..] } else { stem }
2479 // Adds the static "rlib
" versions of all crates to the command line.
2480 // There's a bit of magic which happens here specifically related to LTO,
2481 // namely that we remove upstream object files.
2483 // When performing LTO, almost(*) all of the bytecode from the upstream
2484 // libraries has already been included in our object file output. As a
2485 // result we need to remove the object files in the upstream libraries so
2486 // the linker doesn't try to include them twice (or whine about duplicate
2487 // symbols). We must continue to include the rest of the rlib, however, as
2488 // it may contain static native libraries which must be linked in.
2490 // (*) Crates marked with `#![no_builtins]` don't participate in LTO and
2491 // their bytecode wasn't included. The object files in those libraries must
2492 // still be passed to the linker.
2494 // Note, however, that if we're not doing LTO we can just pass the rlib
2495 // blindly to the linker (fast) because it's fine if it's not actually
2496 // included as we're at the end of the dependency chain.
2497 fn add_static_crate<'a>(
2498 cmd: &mut dyn Linker,
2500 archive_builder_builder: &dyn ArchiveBuilderBuilder,
2501 codegen_results: &CodegenResults,
2505 let src = &codegen_results.crate_info.used_crate_source[&cnum];
2506 let cratepath = &src.rlib.as_ref().unwrap().0;
2508 let mut link_upstream = |path: &Path| {
2509 cmd.link_rlib(&fix_windows_verbatim_for_gcc(path));
2512 // See the comment above in `link_staticlib` and `link_rlib` for why if
2513 // there's a static library that's not relevant we skip all object
2515 let native_libs = &codegen_results.crate_info.native_libraries[&cnum];
2516 let skip_native = native_libs.iter().any(|lib| {
2517 matches!(lib.kind, NativeLibKind::Static { bundle: None | Some(true), .. })
2518 && !relevant_lib(sess, lib)
2521 if (!are_upstream_rust_objects_already_included(sess)
2522 || ignored_for_lto(sess, &codegen_results.crate_info, cnum))
2525 link_upstream(cratepath);
2529 let dst = tmpdir.join(cratepath.file_name().unwrap());
2530 let name = cratepath.file_name().unwrap().to_str().unwrap();
2531 let name = &name[3..name.len() - 5]; // chop off lib/.rlib
2533 sess.prof.generic_activity_with_arg("link_altering_rlib
", name).run(|| {
2534 let canonical_name = name.replace('-', "_
");
2535 let upstream_rust_objects_already_included =
2536 are_upstream_rust_objects_already_included(sess);
2537 let is_builtins = sess.target.no_builtins
2538 || !codegen_results.crate_info.is_no_builtins.contains(&cnum);
2540 let mut archive = archive_builder_builder.new_archive_builder(sess);
2541 if let Err(e) = archive.add_archive(
2544 if f == METADATA_FILENAME {
2548 let canonical = f.replace('-', "_
");
2550 let is_rust_object =
2551 canonical.starts_with(&canonical_name) && looks_like_rust_object_file(&f);
2553 // If we've been requested to skip all native object files
2554 // (those not generated by the rust compiler) then we can skip
2555 // this file. See above for why we may want to do this.
2556 let skip_because_cfg_say_so = skip_native && !is_rust_object;
2558 // If we're performing LTO and this is a rust-generated object
2559 // file, then we don't need the object file as it's part of the
2560 // LTO module. Note that `#![no_builtins]` is excluded from LTO,
2561 // though, so we let that object file slide.
2562 let skip_because_lto =
2563 upstream_rust_objects_already_included && is_rust_object && is_builtins;
2565 if skip_because_cfg_say_so || skip_because_lto {
2572 sess.fatal(&format!("failed to build archive from rlib
: {}
", e));
2574 if archive.build(&dst) {
2575 link_upstream(&dst);
2580 // Same thing as above, but for dynamic crates instead of static crates.
2581 fn add_dynamic_crate(cmd: &mut dyn Linker, sess: &Session, cratepath: &Path) {
2582 // Just need to tell the linker about where the library lives and
2584 let parent = cratepath.parent();
2585 if let Some(dir) = parent {
2586 cmd.include_path(&fix_windows_verbatim_for_gcc(dir));
2588 let filestem = cratepath.file_stem().unwrap().to_str().unwrap();
2589 cmd.link_rust_dylib(
2590 &unlib(&sess.target, filestem),
2591 parent.unwrap_or_else(|| Path::new("")),
2596 /// Link in all of our upstream crates' native dependencies. Remember that all of these upstream
2597 /// native dependencies are all non-static dependencies. We've got two cases then:
2599 /// 1. The upstream crate is an rlib. In this case we *must* link in the native dependency because
2600 /// the rlib is just an archive.
2602 /// 2. The upstream crate is a dylib. In order to use the dylib, we have to have the dependency
2603 /// present on the system somewhere. Thus, we don't gain a whole lot from not linking in the
2604 /// dynamic dependency to this crate as well.
2606 /// The use case for this is a little subtle. In theory the native dependencies of a crate are
2607 /// purely an implementation detail of the crate itself, but the problem arises with generic and
2608 /// inlined functions. If a generic function calls a native function, then the generic function
2609 /// must be instantiated in the target crate, meaning that the native symbol must also be resolved
2610 /// in the target crate.
2611 fn add_upstream_native_libraries(
2612 cmd: &mut dyn Linker,
2614 codegen_results: &CodegenResults,
2616 let mut last = (None, NativeLibKind::Unspecified, None);
2617 for &cnum in &codegen_results.crate_info.used_crates {
2618 for lib in codegen_results.crate_info.native_libraries[&cnum].iter() {
2619 let Some(name) = lib.name else {
2622 let name = name.as_str();
2623 if !relevant_lib(sess, &lib) {
2627 // Skip if this library is the same as the last.
2628 last = if (lib.name, lib.kind, lib.verbatim) == last {
2631 (lib.name, lib.kind, lib.verbatim)
2634 let verbatim = lib.verbatim.unwrap_or(false);
2636 NativeLibKind::Dylib { as_needed } => {
2637 cmd.link_dylib(name, verbatim, as_needed.unwrap_or(true))
2639 NativeLibKind::Unspecified => cmd.link_dylib(name, verbatim, true),
2640 NativeLibKind::Framework { as_needed } => {
2641 cmd.link_framework(name, as_needed.unwrap_or(true))
2643 // ignore static native libraries here as we've
2644 // already included them in add_local_native_libraries and
2645 // add_upstream_rust_crates
2646 NativeLibKind::Static { .. } => {}
2647 NativeLibKind::RawDylib | NativeLibKind::LinkArg => {}
2653 fn relevant_lib(sess: &Session, lib: &NativeLib) -> bool {
2655 Some(ref cfg) => rustc_attr::cfg_matches(cfg, &sess.parse_sess, CRATE_NODE_ID, None),
2660 fn are_upstream_rust_objects_already_included(sess: &Session) -> bool {
2662 config::Lto::Fat => true,
2663 config::Lto::Thin => {
2664 // If we defer LTO to the linker, we haven't run LTO ourselves, so
2665 // any upstream object files have not been copied yet.
2666 !sess.opts.cg.linker_plugin_lto.enabled()
2668 config::Lto::No | config::Lto::ThinLocal => false,
2672 fn add_apple_sdk(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavor) {
2673 let arch = &sess.target.arch;
2674 let os = &sess.target.os;
2675 let llvm_target = &sess.target.llvm_target;
2676 if sess.target.vendor != "apple
"
2677 || !matches!(os.as_ref(), "ios
" | "tvos
" | "watchos
")
2678 || (flavor != LinkerFlavor::Gcc && flavor != LinkerFlavor::Lld(LldFlavor::Ld64))
2682 let sdk_name = match (arch.as_ref(), os.as_ref()) {
2683 ("aarch64
", "tvos
") => "appletvos
",
2684 ("x86_64
", "tvos
") => "appletvsimulator
",
2685 ("arm
", "ios
") => "iphoneos
",
2686 ("aarch64
", "ios
") if llvm_target.contains("macabi
") => "macosx
",
2687 ("aarch64
", "ios
") if llvm_target.ends_with("-simulator
") => "iphonesimulator
",
2688 ("aarch64
", "ios
") => "iphoneos
",
2689 ("x86
", "ios
") => "iphonesimulator
",
2690 ("x86_64
", "ios
") if llvm_target.contains("macabi
") => "macosx
",
2691 ("x86_64
", "ios
") => "iphonesimulator
",
2692 ("x86_64
", "watchos
") => "watchsimulator
",
2693 ("arm64_32
", "watchos
") => "watchos
",
2694 ("aarch64
", "watchos
") if llvm_target.ends_with("-simulator
") => "watchsimulator
",
2695 ("aarch64
", "watchos
") => "watchos
",
2696 ("arm
", "watchos
") => "watchos
",
2698 sess.err(&format!("unsupported arch `{}`
for os `{}`
", arch, os));
2702 let sdk_root = match get_apple_sdk_root(sdk_name) {
2711 LinkerFlavor::Gcc => {
2712 cmd.args(&["-isysroot
", &sdk_root, "-Wl
,-syslibroot
", &sdk_root]);
2714 LinkerFlavor::Lld(LldFlavor::Ld64) => {
2715 cmd.args(&["-syslibroot
", &sdk_root]);
2717 _ => unreachable!(),
2721 fn get_apple_sdk_root(sdk_name: &str) -> Result<String, String> {
2722 // Following what clang does
2723 // (https://github.com/llvm/llvm-project/blob/
2724 // 296a80102a9b72c3eda80558fb78a3ed8849b341/clang/lib/Driver/ToolChains/Darwin.cpp#L1661-L1678)
2725 // to allow the SDK path to be set. (For clang, xcrun sets
2726 // SDKROOT; for rustc, the user or build system can set it, or we
2727 // can fall back to checking for xcrun on PATH.)
2728 if let Ok(sdkroot) = env::var("SDKROOT
") {
2729 let p = Path::new(&sdkroot);
2731 // Ignore `SDKROOT` if it's clearly set for the wrong platform.
2733 if sdkroot.contains("TVSimulator
.platform
")
2734 || sdkroot.contains("MacOSX
.platform
") => {}
2736 if sdkroot.contains("TVOS
.platform
") || sdkroot.contains("MacOSX
.platform
") => {}
2738 if sdkroot.contains("iPhoneSimulator
.platform
")
2739 || sdkroot.contains("MacOSX
.platform
") => {}
2741 if sdkroot.contains("iPhoneOS
.platform
") || sdkroot.contains("MacOSX
.platform
") => {
2744 if sdkroot.contains("iPhoneOS
.platform
")
2745 || sdkroot.contains("iPhoneSimulator
.platform
") => {}
2747 if sdkroot.contains("WatchSimulator
.platform
")
2748 || sdkroot.contains("MacOSX
.platform
") => {}
2750 if sdkroot.contains("WatchOS
.platform
") || sdkroot.contains("MacOSX
.platform
") => {}
2751 // Ignore `SDKROOT` if it's not a valid path.
2752 _ if !p.is_absolute() || p == Path::new("/") || !p.exists() => {}
2753 _ => return Ok(sdkroot),
2757 Command::new("xcrun
").arg("--show
-sdk
-path
").arg("-sdk
").arg(sdk_name).output().and_then(
2759 if output.status.success() {
2760 Ok(String::from_utf8(output.stdout).unwrap())
2762 let error = String::from_utf8(output.stderr);
2763 let error = format!("process exit with error
: {}
", error.unwrap());
2764 Err(io::Error::new(io::ErrorKind::Other, &error[..]))
2770 Ok(output) => Ok(output.trim().to_string()),
2771 Err(e) => Err(format!("failed to get {} SDK path
: {}
", sdk_name, e)),
2775 fn add_gcc_ld_path(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavor) {
2776 if let Some(ld_impl) = sess.opts.unstable_opts.gcc_ld {
2777 if let LinkerFlavor::Gcc = flavor {
2780 let tools_path = sess.get_tools_search_paths(false);
2781 let gcc_ld_dir = tools_path
2783 .map(|p| p.join("gcc
-ld
"))
2785 p.join(if sess.host.is_like_windows { "ld.exe" } else { "ld" }).exists()
2787 .unwrap_or_else(|| sess.fatal("rust
-lld (as ld
) not found
"));
2789 let mut arg = OsString::from("-B
");
2790 arg.push(gcc_ld_dir);
2793 cmd.arg(format!("-Wl
,-rustc
-lld
-flavor
={}
", sess.target.lld_flavor.as_str()));
2797 sess.fatal("option `
-Z gcc
-ld` is used even though linker flavor is not gcc
");