diff options
Diffstat (limited to 'compiler/rustc_codegen_ssa/src/back/link.rs')
| -rw-r--r-- | compiler/rustc_codegen_ssa/src/back/link.rs | 2152 |
1 files changed, 2152 insertions, 0 deletions
diff --git a/compiler/rustc_codegen_ssa/src/back/link.rs b/compiler/rustc_codegen_ssa/src/back/link.rs new file mode 100644 index 00000000000..bfcf979d125 --- /dev/null +++ b/compiler/rustc_codegen_ssa/src/back/link.rs @@ -0,0 +1,2152 @@ +use rustc_data_structures::fx::FxHashSet; +use rustc_data_structures::temp_dir::MaybeTempDir; +use rustc_fs_util::fix_windows_verbatim_for_gcc; +use rustc_hir::def_id::CrateNum; +use rustc_middle::middle::cstore::{EncodedMetadata, LibSource, NativeLib}; +use rustc_middle::middle::dependency_format::Linkage; +use rustc_session::config::{self, CFGuard, CrateType, DebugInfo}; +use rustc_session::config::{OutputFilenames, OutputType, PrintRequest, SanitizerSet}; +use rustc_session::output::{check_file_is_writeable, invalid_output_for_target, out_filename}; +use rustc_session::search_paths::PathKind; +use rustc_session::utils::NativeLibKind; +/// For all the linkers we support, and information they might +/// need out of the shared crate context before we get rid of it. +use rustc_session::{filesearch, Session}; +use rustc_span::symbol::Symbol; +use rustc_target::spec::crt_objects::{CrtObjects, CrtObjectsFallback}; +use rustc_target::spec::{LinkOutputKind, LinkerFlavor, LldFlavor}; +use rustc_target::spec::{PanicStrategy, RelocModel, RelroLevel}; + +use super::archive::ArchiveBuilder; +use super::command::Command; +use super::linker::{self, Linker}; +use super::rpath::{self, RPathConfig}; +use crate::{looks_like_rust_object_file, CodegenResults, CrateInfo, METADATA_FILENAME}; + +use cc::windows_registry; +use tempfile::Builder as TempFileBuilder; + +use std::ffi::OsString; +use std::path::{Path, PathBuf}; +use std::process::{ExitStatus, Output, Stdio}; +use std::{ascii, char, env, fmt, fs, io, mem, str}; + +pub fn remove(sess: &Session, path: &Path) { + if let Err(e) = fs::remove_file(path) { + sess.err(&format!("failed to remove {}: {}", path.display(), e)); + } +} + +/// Performs the linkage portion of the compilation phase. This will generate all +/// of the requested outputs for this compilation session. +pub fn link_binary<'a, B: ArchiveBuilder<'a>>( + sess: &'a Session, + codegen_results: &CodegenResults, + outputs: &OutputFilenames, + crate_name: &str, + target_cpu: &str, +) { + let _timer = sess.timer("link_binary"); + let output_metadata = sess.opts.output_types.contains_key(&OutputType::Metadata); + for &crate_type in sess.crate_types().iter() { + // Ignore executable crates if we have -Z no-codegen, as they will error. + if (sess.opts.debugging_opts.no_codegen || !sess.opts.output_types.should_codegen()) + && !output_metadata + && crate_type == CrateType::Executable + { + continue; + } + + if invalid_output_for_target(sess, crate_type) { + bug!( + "invalid output type `{:?}` for target os `{}`", + crate_type, + sess.opts.target_triple + ); + } + + sess.time("link_binary_check_files_are_writeable", || { + for obj in codegen_results.modules.iter().filter_map(|m| m.object.as_ref()) { + check_file_is_writeable(obj, sess); + } + }); + + if outputs.outputs.should_codegen() { + let tmpdir = TempFileBuilder::new() + .prefix("rustc") + .tempdir() + .unwrap_or_else(|err| sess.fatal(&format!("couldn't create a temp dir: {}", err))); + let path = MaybeTempDir::new(tmpdir, sess.opts.cg.save_temps); + let out_filename = out_filename(sess, crate_type, outputs, crate_name); + match crate_type { + CrateType::Rlib => { + let _timer = sess.timer("link_rlib"); + link_rlib::<B>(sess, codegen_results, RlibFlavor::Normal, &out_filename, &path) + .build(); + } + CrateType::Staticlib => { + link_staticlib::<B>(sess, codegen_results, &out_filename, &path); + } + _ => { + link_natively::<B>( + sess, + crate_type, + &out_filename, + codegen_results, + path.as_ref(), + target_cpu, + ); + } + } + if sess.opts.json_artifact_notifications { + sess.parse_sess.span_diagnostic.emit_artifact_notification(&out_filename, "link"); + } + } + } + + // Remove the temporary object file and metadata if we aren't saving temps + sess.time("link_binary_remove_temps", || { + if !sess.opts.cg.save_temps { + if sess.opts.output_types.should_codegen() + && !preserve_objects_for_their_debuginfo(sess) + { + for obj in codegen_results.modules.iter().filter_map(|m| m.object.as_ref()) { + remove(sess, obj); + } + } + if let Some(ref metadata_module) = codegen_results.metadata_module { + if let Some(ref obj) = metadata_module.object { + remove(sess, obj); + } + } + if let Some(ref allocator_module) = codegen_results.allocator_module { + if let Some(ref obj) = allocator_module.object { + remove(sess, obj); + } + } + } + }); +} + +// The third parameter is for env vars, used on windows to set up the +// path for MSVC to find its DLLs, and gcc to find its bundled +// toolchain +fn get_linker( + sess: &Session, + linker: &Path, + flavor: LinkerFlavor, + self_contained: bool, +) -> Command { + let msvc_tool = windows_registry::find_tool(&sess.opts.target_triple.triple(), "link.exe"); + + // If our linker looks like a batch script on Windows then to execute this + // we'll need to spawn `cmd` explicitly. This is primarily done to handle + // emscripten where the linker is `emcc.bat` and needs to be spawned as + // `cmd /c emcc.bat ...`. + // + // This worked historically but is needed manually since #42436 (regression + // was tagged as #42791) and some more info can be found on #44443 for + // emscripten itself. + let mut cmd = match linker.to_str() { + Some(linker) if cfg!(windows) && linker.ends_with(".bat") => Command::bat_script(linker), + _ => match flavor { + LinkerFlavor::Lld(f) => Command::lld(linker, f), + LinkerFlavor::Msvc + if sess.opts.cg.linker.is_none() && sess.target.target.options.linker.is_none() => + { + Command::new(msvc_tool.as_ref().map(|t| t.path()).unwrap_or(linker)) + } + _ => Command::new(linker), + }, + }; + + // UWP apps have API restrictions enforced during Store submissions. + // To comply with the Windows App Certification Kit, + // MSVC needs to link with the Store versions of the runtime libraries (vcruntime, msvcrt, etc). + let t = &sess.target.target; + if (flavor == LinkerFlavor::Msvc || flavor == LinkerFlavor::Lld(LldFlavor::Link)) + && t.target_vendor == "uwp" + { + if let Some(ref tool) = msvc_tool { + let original_path = tool.path(); + if let Some(ref root_lib_path) = original_path.ancestors().nth(4) { + let arch = match t.arch.as_str() { + "x86_64" => Some("x64".to_string()), + "x86" => Some("x86".to_string()), + "aarch64" => Some("arm64".to_string()), + "arm" => Some("arm".to_string()), + _ => None, + }; + if let Some(ref a) = arch { + // FIXME: Move this to `fn linker_with_args`. + let mut arg = OsString::from("/LIBPATH:"); + arg.push(format!("{}\\lib\\{}\\store", root_lib_path.display(), a.to_string())); + cmd.arg(&arg); + } else { + warn!("arch is not supported"); + } + } else { + warn!("MSVC root path lib location not found"); + } + } else { + warn!("link.exe not found"); + } + } + + // The compiler's sysroot often has some bundled tools, so add it to the + // PATH for the child. + let mut new_path = sess.host_filesearch(PathKind::All).get_tools_search_paths(self_contained); + let mut msvc_changed_path = false; + if sess.target.target.options.is_like_msvc { + if let Some(ref tool) = msvc_tool { + cmd.args(tool.args()); + for &(ref k, ref v) in tool.env() { + if k == "PATH" { + new_path.extend(env::split_paths(v)); + msvc_changed_path = true; + } else { + cmd.env(k, v); + } + } + } + } + + if !msvc_changed_path { + if let Some(path) = env::var_os("PATH") { + new_path.extend(env::split_paths(&path)); + } + } + cmd.env("PATH", env::join_paths(new_path).unwrap()); + + cmd +} + +pub fn each_linked_rlib( + info: &CrateInfo, + f: &mut dyn FnMut(CrateNum, &Path), +) -> Result<(), String> { + let crates = info.used_crates_static.iter(); + let mut fmts = None; + for (ty, list) in info.dependency_formats.iter() { + match ty { + CrateType::Executable + | CrateType::Staticlib + | CrateType::Cdylib + | CrateType::ProcMacro => { + fmts = Some(list); + break; + } + _ => {} + } + } + let fmts = match fmts { + Some(f) => f, + None => return Err("could not find formats for rlibs".to_string()), + }; + for &(cnum, ref path) in crates { + match fmts.get(cnum.as_usize() - 1) { + Some(&Linkage::NotLinked | &Linkage::IncludedFromDylib) => continue, + Some(_) => {} + None => return Err("could not find formats for rlibs".to_string()), + } + let name = &info.crate_name[&cnum]; + let path = match *path { + LibSource::Some(ref p) => p, + LibSource::MetadataOnly => { + return Err(format!( + "could not find rlib for: `{}`, found rmeta (metadata) file", + name + )); + } + LibSource::None => return Err(format!("could not find rlib for: `{}`", name)), + }; + f(cnum, &path); + } + Ok(()) +} + +/// We use a temp directory here to avoid races between concurrent rustc processes, +/// such as builds in the same directory using the same filename for metadata while +/// building an `.rlib` (stomping over one another), or writing an `.rmeta` into a +/// directory being searched for `extern crate` (observing an incomplete file). +/// The returned path is the temporary file containing the complete metadata. +pub fn emit_metadata(sess: &Session, metadata: &EncodedMetadata, tmpdir: &MaybeTempDir) -> PathBuf { + let out_filename = tmpdir.as_ref().join(METADATA_FILENAME); + let result = fs::write(&out_filename, &metadata.raw_data); + + if let Err(e) = result { + sess.fatal(&format!("failed to write {}: {}", out_filename.display(), e)); + } + + out_filename +} + +// Create an 'rlib' +// +// An rlib in its current incarnation is essentially a renamed .a file. The +// rlib primarily contains the object file of the crate, but it also contains +// all of the object files from native libraries. This is done by unzipping +// native libraries and inserting all of the contents into this archive. +fn link_rlib<'a, B: ArchiveBuilder<'a>>( + sess: &'a Session, + codegen_results: &CodegenResults, + flavor: RlibFlavor, + out_filename: &Path, + tmpdir: &MaybeTempDir, +) -> B { + info!("preparing rlib to {:?}", out_filename); + let mut ab = <B as ArchiveBuilder>::new(sess, out_filename, None); + + for obj in codegen_results.modules.iter().filter_map(|m| m.object.as_ref()) { + ab.add_file(obj); + } + + // Note that in this loop we are ignoring the value of `lib.cfg`. That is, + // we may not be configured to actually include a static library if we're + // adding it here. That's because later when we consume this rlib we'll + // decide whether we actually needed the static library or not. + // + // To do this "correctly" we'd need to keep track of which libraries added + // which object files to the archive. We don't do that here, however. The + // #[link(cfg(..))] feature is unstable, though, and only intended to get + // liblibc working. In that sense the check below just indicates that if + // there are any libraries we want to omit object files for at link time we + // just exclude all custom object files. + // + // Eventually if we want to stabilize or flesh out the #[link(cfg(..))] + // feature then we'll need to figure out how to record what objects were + // loaded from the libraries found here and then encode that into the + // metadata of the rlib we're generating somehow. + for lib in codegen_results.crate_info.used_libraries.iter() { + match lib.kind { + NativeLibKind::StaticBundle => {} + NativeLibKind::StaticNoBundle + | NativeLibKind::Dylib + | NativeLibKind::Framework + | NativeLibKind::RawDylib + | NativeLibKind::Unspecified => continue, + } + if let Some(name) = lib.name { + ab.add_native_library(name); + } + } + + // After adding all files to the archive, we need to update the + // symbol table of the archive. + ab.update_symbols(); + + // Note that it is important that we add all of our non-object "magical + // files" *after* all of the object files in the archive. The reason for + // this is as follows: + // + // * When performing LTO, this archive will be modified to remove + // objects from above. The reason for this is described below. + // + // * When the system linker looks at an archive, it will attempt to + // determine the architecture of the archive in order to see whether its + // linkable. + // + // The algorithm for this detection is: iterate over the files in the + // archive. Skip magical SYMDEF names. Interpret the first file as an + // object file. Read architecture from the object file. + // + // * As one can probably see, if "metadata" and "foo.bc" were placed + // before all of the objects, then the architecture of this archive would + // not be correctly inferred once 'foo.o' is removed. + // + // Basically, all this means is that this code should not move above the + // code above. + match flavor { + RlibFlavor::Normal => { + // Instead of putting the metadata in an object file section, rlibs + // contain the metadata in a separate file. + ab.add_file(&emit_metadata(sess, &codegen_results.metadata, tmpdir)); + + // After adding all files to the archive, we need to update the + // symbol table of the archive. This currently dies on macOS (see + // #11162), and isn't necessary there anyway + if !sess.target.target.options.is_like_osx { + ab.update_symbols(); + } + } + + RlibFlavor::StaticlibBase => { + let obj = codegen_results.allocator_module.as_ref().and_then(|m| m.object.as_ref()); + if let Some(obj) = obj { + ab.add_file(obj); + } + } + } + + ab +} + +// Create a static archive +// +// This is essentially the same thing as an rlib, but it also involves adding +// all of the upstream crates' objects into the archive. This will slurp in +// all of the native libraries of upstream dependencies as well. +// +// Additionally, there's no way for us to link dynamic libraries, so we warn +// about all dynamic library dependencies that they're not linked in. +// +// There's no need to include metadata in a static archive, so ensure to not +// link in the metadata object file (and also don't prepare the archive with a +// metadata file). +fn link_staticlib<'a, B: ArchiveBuilder<'a>>( + sess: &'a Session, + codegen_results: &CodegenResults, + out_filename: &Path, + tempdir: &MaybeTempDir, +) { + let mut ab = + link_rlib::<B>(sess, codegen_results, RlibFlavor::StaticlibBase, out_filename, tempdir); + let mut all_native_libs = vec![]; + + let res = each_linked_rlib(&codegen_results.crate_info, &mut |cnum, path| { + let name = &codegen_results.crate_info.crate_name[&cnum]; + let native_libs = &codegen_results.crate_info.native_libraries[&cnum]; + + // Here when we include the rlib into our staticlib we need to make a + // decision whether to include the extra object files along the way. + // These extra object files come from statically included native + // libraries, but they may be cfg'd away with #[link(cfg(..))]. + // + // This unstable feature, though, only needs liblibc to work. The only + // use case there is where musl is statically included in liblibc.rlib, + // so if we don't want the included version we just need to skip it. As + // a result the logic here is that if *any* linked library is cfg'd away + // we just skip all object files. + // + // Clearly this is not sufficient for a general purpose feature, and + // we'd want to read from the library's metadata to determine which + // object files come from where and selectively skip them. + let skip_object_files = native_libs + .iter() + .any(|lib| lib.kind == NativeLibKind::StaticBundle && !relevant_lib(sess, lib)); + ab.add_rlib( + path, + &name.as_str(), + are_upstream_rust_objects_already_included(sess) + && !ignored_for_lto(sess, &codegen_results.crate_info, cnum), + skip_object_files, + ) + .unwrap(); + + all_native_libs.extend(codegen_results.crate_info.native_libraries[&cnum].iter().cloned()); + }); + if let Err(e) = res { + sess.fatal(&e); + } + + ab.update_symbols(); + ab.build(); + + if !all_native_libs.is_empty() { + if sess.opts.prints.contains(&PrintRequest::NativeStaticLibs) { + print_native_static_libs(sess, &all_native_libs); + } + } +} + +// Create a dynamic library or executable +// +// This will invoke the system linker/cc to create the resulting file. This +// links to all upstream files as well. +fn link_natively<'a, B: ArchiveBuilder<'a>>( + sess: &'a Session, + crate_type: CrateType, + out_filename: &Path, + codegen_results: &CodegenResults, + tmpdir: &Path, + target_cpu: &str, +) { + info!("preparing {:?} to {:?}", crate_type, out_filename); + let (linker_path, flavor) = linker_and_flavor(sess); + let mut cmd = linker_with_args::<B>( + &linker_path, + flavor, + sess, + crate_type, + tmpdir, + out_filename, + codegen_results, + target_cpu, + ); + + linker::disable_localization(&mut cmd); + + for &(ref k, ref v) in &sess.target.target.options.link_env { + cmd.env(k, v); + } + for k in &sess.target.target.options.link_env_remove { + cmd.env_remove(k); + } + + if sess.opts.debugging_opts.print_link_args { + println!("{:?}", &cmd); + } + + // May have not found libraries in the right formats. + sess.abort_if_errors(); + + // Invoke the system linker + info!("{:?}", &cmd); + let retry_on_segfault = env::var("RUSTC_RETRY_LINKER_ON_SEGFAULT").is_ok(); + let mut prog; + let mut i = 0; + loop { + i += 1; + prog = sess.time("run_linker", || exec_linker(sess, &cmd, out_filename, tmpdir)); + let output = match prog { + Ok(ref output) => output, + Err(_) => break, + }; + if output.status.success() { + break; + } + let mut out = output.stderr.clone(); + out.extend(&output.stdout); + let out = String::from_utf8_lossy(&out); + + // Check to see if the link failed with "unrecognized command line option: + // '-no-pie'" for gcc or "unknown argument: '-no-pie'" for clang. If so, + // reperform the link step without the -no-pie option. This is safe because + // if the linker doesn't support -no-pie then it should not default to + // linking executables as pie. Different versions of gcc seem to use + // different quotes in the error message so don't check for them. + if sess.target.target.options.linker_is_gnu + && flavor != LinkerFlavor::Ld + && (out.contains("unrecognized command line option") + || out.contains("unknown argument")) + && out.contains("-no-pie") + && cmd.get_args().iter().any(|e| e.to_string_lossy() == "-no-pie") + { + info!("linker output: {:?}", out); + warn!("Linker does not support -no-pie command line option. Retrying without."); + for arg in cmd.take_args() { + if arg.to_string_lossy() != "-no-pie" { + cmd.arg(arg); + } + } + info!("{:?}", &cmd); + continue; + } + + // Detect '-static-pie' used with an older version of gcc or clang not supporting it. + // Fallback from '-static-pie' to '-static' in that case. + if sess.target.target.options.linker_is_gnu + && flavor != LinkerFlavor::Ld + && (out.contains("unrecognized command line option") + || out.contains("unknown argument")) + && (out.contains("-static-pie") || out.contains("--no-dynamic-linker")) + && cmd.get_args().iter().any(|e| e.to_string_lossy() == "-static-pie") + { + info!("linker output: {:?}", out); + warn!( + "Linker does not support -static-pie command line option. Retrying with -static instead." + ); + // Mirror `add_(pre,post)_link_objects` to replace CRT objects. + let self_contained = crt_objects_fallback(sess, crate_type); + let opts = &sess.target.target.options; + let pre_objects = if self_contained { + &opts.pre_link_objects_fallback + } else { + &opts.pre_link_objects + }; + let post_objects = if self_contained { + &opts.post_link_objects_fallback + } else { + &opts.post_link_objects + }; + let get_objects = |objects: &CrtObjects, kind| { + objects + .get(&kind) + .iter() + .copied() + .flatten() + .map(|obj| get_object_file_path(sess, obj, self_contained).into_os_string()) + .collect::<Vec<_>>() + }; + let pre_objects_static_pie = get_objects(pre_objects, LinkOutputKind::StaticPicExe); + let post_objects_static_pie = get_objects(post_objects, LinkOutputKind::StaticPicExe); + let mut pre_objects_static = get_objects(pre_objects, LinkOutputKind::StaticNoPicExe); + let mut post_objects_static = get_objects(post_objects, LinkOutputKind::StaticNoPicExe); + // Assume that we know insertion positions for the replacement arguments from replaced + // arguments, which is true for all supported targets. + assert!(pre_objects_static.is_empty() || !pre_objects_static_pie.is_empty()); + assert!(post_objects_static.is_empty() || !post_objects_static_pie.is_empty()); + for arg in cmd.take_args() { + if arg.to_string_lossy() == "-static-pie" { + // Replace the output kind. + cmd.arg("-static"); + } else if pre_objects_static_pie.contains(&arg) { + // Replace the pre-link objects (replace the first and remove the rest). + cmd.args(mem::take(&mut pre_objects_static)); + } else if post_objects_static_pie.contains(&arg) { + // Replace the post-link objects (replace the first and remove the rest). + cmd.args(mem::take(&mut post_objects_static)); + } else { + cmd.arg(arg); + } + } + info!("{:?}", &cmd); + continue; + } + + // Here's a terribly awful hack that really shouldn't be present in any + // compiler. Here an environment variable is supported to automatically + // retry the linker invocation if the linker looks like it segfaulted. + // + // Gee that seems odd, normally segfaults are things we want to know + // about! Unfortunately though in rust-lang/rust#38878 we're + // experiencing the linker segfaulting on Travis quite a bit which is + // causing quite a bit of pain to land PRs when they spuriously fail + // due to a segfault. + // + // The issue #38878 has some more debugging information on it as well, + // but this unfortunately looks like it's just a race condition in + // macOS's linker with some thread pool working in the background. It + // seems that no one currently knows a fix for this so in the meantime + // we're left with this... + if !retry_on_segfault || i > 3 { + break; + } + let msg_segv = "clang: error: unable to execute command: Segmentation fault: 11"; + let msg_bus = "clang: error: unable to execute command: Bus error: 10"; + if out.contains(msg_segv) || out.contains(msg_bus) { + warn!( + "looks like the linker segfaulted when we tried to call it, \ + automatically retrying again. cmd = {:?}, out = {}.", + cmd, out, + ); + continue; + } + + if is_illegal_instruction(&output.status) { + warn!( + "looks like the linker hit an illegal instruction when we \ + tried to call it, automatically retrying again. cmd = {:?}, ]\ + out = {}, status = {}.", + cmd, out, output.status, + ); + continue; + } + + #[cfg(unix)] + fn is_illegal_instruction(status: &ExitStatus) -> bool { + use std::os::unix::prelude::*; + status.signal() == Some(libc::SIGILL) + } + + #[cfg(windows)] + fn is_illegal_instruction(_status: &ExitStatus) -> bool { + false + } + } + + match prog { + Ok(prog) => { + fn escape_string(s: &[u8]) -> String { + str::from_utf8(s).map(|s| s.to_owned()).unwrap_or_else(|_| { + let mut x = "Non-UTF-8 output: ".to_string(); + x.extend(s.iter().flat_map(|&b| ascii::escape_default(b)).map(char::from)); + x + }) + } + if !prog.status.success() { + let mut output = prog.stderr.clone(); + output.extend_from_slice(&prog.stdout); + sess.struct_err(&format!( + "linking with `{}` failed: {}", + linker_path.display(), + prog.status + )) + .note(&format!("{:?}", &cmd)) + .note(&escape_string(&output)) + .emit(); + + // If MSVC's `link.exe` was expected but the return code + // is not a Microsoft LNK error then suggest a way to fix or + // install the Visual Studio build tools. + if let Some(code) = prog.status.code() { + if sess.target.target.options.is_like_msvc + && flavor == LinkerFlavor::Msvc + // Respect the command line override + && sess.opts.cg.linker.is_none() + // Match exactly "link.exe" + && linker_path.to_str() == Some("link.exe") + // All Microsoft `link.exe` linking error codes are + // four digit numbers in the range 1000 to 9999 inclusive + && (code < 1000 || code > 9999) + { + let is_vs_installed = windows_registry::find_vs_version().is_ok(); + let has_linker = windows_registry::find_tool( + &sess.opts.target_triple.triple(), + "link.exe", + ) + .is_some(); + + sess.note_without_error("`link.exe` returned an unexpected error"); + if is_vs_installed && has_linker { + // the linker is broken + sess.note_without_error( + "the Visual Studio build tools may need to be repaired \ + using the Visual Studio installer", + ); + sess.note_without_error( + "or a necessary component may be missing from the \ + \"C++ build tools\" workload", + ); + } else if is_vs_installed { + // the linker is not installed + sess.note_without_error( + "in the Visual Studio installer, ensure the \ + \"C++ build tools\" workload is selected", + ); + } else { + // visual studio is not installed + sess.note_without_error( + "you may need to install Visual Studio build tools with the \ + \"C++ build tools\" workload", + ); + } + } + } + + sess.abort_if_errors(); + } + info!("linker stderr:\n{}", escape_string(&prog.stderr)); + info!("linker stdout:\n{}", escape_string(&prog.stdout)); + } + Err(e) => { + let linker_not_found = e.kind() == io::ErrorKind::NotFound; + + let mut linker_error = { + if linker_not_found { + sess.struct_err(&format!("linker `{}` not found", linker_path.display())) + } else { + sess.struct_err(&format!( + "could not exec the linker `{}`", + linker_path.display() + )) + } + }; + + linker_error.note(&e.to_string()); + + if !linker_not_found { + linker_error.note(&format!("{:?}", &cmd)); + } + + linker_error.emit(); + + if sess.target.target.options.is_like_msvc && linker_not_found { + sess.note_without_error( + "the msvc targets depend on the msvc linker \ + but `link.exe` was not found", + ); + sess.note_without_error( + "please ensure that VS 2013, VS 2015, VS 2017 or VS 2019 \ + was installed with the Visual C++ option", + ); + } + sess.abort_if_errors(); + } + } + + // On macOS, debuggers need this utility to get run to do some munging of + // the symbols. Note, though, that if the object files are being preserved + // for their debug information there's no need for us to run dsymutil. + if sess.target.target.options.is_like_osx + && sess.opts.debuginfo != DebugInfo::None + && !preserve_objects_for_their_debuginfo(sess) + { + if let Err(e) = Command::new("dsymutil").arg(out_filename).output() { + sess.fatal(&format!("failed to run dsymutil: {}", e)) + } + } +} + +fn link_sanitizers(sess: &Session, crate_type: CrateType, linker: &mut dyn Linker) { + // On macOS the runtimes are distributed as dylibs which should be linked to + // both executables and dynamic shared objects. Everywhere else the runtimes + // are currently distributed as static liraries which should be linked to + // executables only. + let needs_runtime = match crate_type { + CrateType::Executable => true, + CrateType::Dylib | CrateType::Cdylib | CrateType::ProcMacro => { + sess.target.target.options.is_like_osx + } + CrateType::Rlib | CrateType::Staticlib => false, + }; + + if !needs_runtime { + return; + } + + let sanitizer = sess.opts.debugging_opts.sanitizer; + if sanitizer.contains(SanitizerSet::ADDRESS) { + link_sanitizer_runtime(sess, linker, "asan"); + } + if sanitizer.contains(SanitizerSet::LEAK) { + link_sanitizer_runtime(sess, linker, "lsan"); + } + if sanitizer.contains(SanitizerSet::MEMORY) { + link_sanitizer_runtime(sess, linker, "msan"); + } + if sanitizer.contains(SanitizerSet::THREAD) { + link_sanitizer_runtime(sess, linker, "tsan"); + } +} + +fn link_sanitizer_runtime(sess: &Session, linker: &mut dyn Linker, name: &str) { + let default_sysroot = filesearch::get_or_default_sysroot(); + let default_tlib = + filesearch::make_target_lib_path(&default_sysroot, sess.opts.target_triple.triple()); + let channel = option_env!("CFG_RELEASE_CHANNEL") + .map(|channel| format!("-{}", channel)) + .unwrap_or_default(); + + match sess.opts.target_triple.triple() { + "x86_64-apple-darwin" => { + // On Apple platforms, the sanitizer is always built as a dylib, and + // LLVM will link to `@rpath/*.dylib`, so we need to specify an + // rpath to the library as well (the rpath should be absolute, see + // PR #41352 for details). + let libname = format!("rustc{}_rt.{}", channel, name); + let rpath = default_tlib.to_str().expect("non-utf8 component in path"); + linker.args(&["-Wl,-rpath", "-Xlinker", rpath]); + linker.link_dylib(Symbol::intern(&libname)); + } + "aarch64-fuchsia" + | "aarch64-unknown-linux-gnu" + | "x86_64-fuchsia" + | "x86_64-unknown-freebsd" + | "x86_64-unknown-linux-gnu" => { + let filename = format!("librustc{}_rt.{}.a", channel, name); + let path = default_tlib.join(&filename); + linker.link_whole_rlib(&path); + } + _ => {} + } +} + +/// Returns a boolean indicating whether the specified crate should be ignored +/// during LTO. +/// +/// Crates ignored during LTO are not lumped together in the "massive object +/// file" that we create and are linked in their normal rlib states. See +/// comments below for what crates do not participate in LTO. +/// +/// It's unusual for a crate to not participate in LTO. Typically only +/// compiler-specific and unstable crates have a reason to not participate in +/// LTO. +pub fn ignored_for_lto(sess: &Session, info: &CrateInfo, cnum: CrateNum) -> bool { + // If our target enables builtin function lowering in LLVM then the + // crates providing these functions don't participate in LTO (e.g. + // no_builtins or compiler builtins crates). + !sess.target.target.options.no_builtins + && (info.compiler_builtins == Some(cnum) || info.is_no_builtins.contains(&cnum)) +} + +fn linker_and_flavor(sess: &Session) -> (PathBuf, LinkerFlavor) { + fn infer_from( + sess: &Session, + linker: Option<PathBuf>, + flavor: Option<LinkerFlavor>, + ) -> Option<(PathBuf, LinkerFlavor)> { + match (linker, flavor) { + (Some(linker), Some(flavor)) => Some((linker, flavor)), + // only the linker flavor is known; use the default linker for the selected flavor + (None, Some(flavor)) => Some(( + PathBuf::from(match flavor { + LinkerFlavor::Em => { + if cfg!(windows) { + "emcc.bat" + } else { + "emcc" + } + } + LinkerFlavor::Gcc => { + if cfg!(any(target_os = "solaris", target_os = "illumos")) { + // On historical Solaris systems, "cc" may have + // been Sun Studio, which is not flag-compatible + // with "gcc". This history casts a long shadow, + // and many modern illumos distributions today + // ship GCC as "gcc" without also making it + // available as "cc". + "gcc" + } else { + "cc" + } + } + LinkerFlavor::Ld => "ld", + LinkerFlavor::Msvc => "link.exe", + LinkerFlavor::Lld(_) => "lld", + LinkerFlavor::PtxLinker => "rust-ptx-linker", + }), + flavor, + )), + (Some(linker), None) => { + let stem = linker.file_stem().and_then(|stem| stem.to_str()).unwrap_or_else(|| { + sess.fatal("couldn't extract file stem from specified linker") + }); + + let flavor = if stem == "emcc" { + LinkerFlavor::Em + } else if stem == "gcc" + || stem.ends_with("-gcc") + || stem == "clang" + || stem.ends_with("-clang") + { + LinkerFlavor::Gcc + } else if stem == "ld" || stem == "ld.lld" || stem.ends_with("-ld") { + LinkerFlavor::Ld + } else if stem == "link" || stem == "lld-link" { + LinkerFlavor::Msvc + } else if stem == "lld" || stem == "rust-lld" { + LinkerFlavor::Lld(sess.target.target.options.lld_flavor) + } else { + // fall back to the value in the target spec + sess.target.target.linker_flavor + }; + + Some((linker, flavor)) + } + (None, None) => None, + } + } + + // linker and linker flavor specified via command line have precedence over what the target + // specification specifies + if let Some(ret) = infer_from(sess, sess.opts.cg.linker.clone(), sess.opts.cg.linker_flavor) { + return ret; + } + + if let Some(ret) = infer_from( + sess, + sess.target.target.options.linker.clone().map(PathBuf::from), + Some(sess.target.target.linker_flavor), + ) { + return ret; + } + + bug!("Not enough information provided to determine how to invoke the linker"); +} + +/// Returns a boolean indicating whether we should preserve the object files on +/// the filesystem for their debug information. This is often useful with +/// split-dwarf like schemes. +fn preserve_objects_for_their_debuginfo(sess: &Session) -> bool { + // If the objects don't have debuginfo there's nothing to preserve. + if sess.opts.debuginfo == config::DebugInfo::None { + return false; + } + + // If we're only producing artifacts that are archives, no need to preserve + // the objects as they're losslessly contained inside the archives. + let output_linked = + sess.crate_types().iter().any(|&x| x != CrateType::Rlib && x != CrateType::Staticlib); + if !output_linked { + return false; + } + + // If we're on OSX then the equivalent of split dwarf is turned on by + // default. The final executable won't actually have any debug information + // except it'll have pointers to elsewhere. Historically we've always run + // `dsymutil` to "link all the dwarf together" but this is actually sort of + // a bummer for incremental compilation! (the whole point of split dwarf is + // that you don't do this sort of dwarf link). + // + // Basically as a result this just means that if we're on OSX and we're + // *not* running dsymutil then the object files are the only source of truth + // for debug information, so we must preserve them. + if sess.target.target.options.is_like_osx { + return !sess.opts.debugging_opts.run_dsymutil; + } + + false +} + +pub fn archive_search_paths(sess: &Session) -> Vec<PathBuf> { + sess.target_filesearch(PathKind::Native).search_path_dirs() +} + +enum RlibFlavor { + Normal, + StaticlibBase, +} + +fn print_native_static_libs(sess: &Session, all_native_libs: &[NativeLib]) { + let lib_args: Vec<_> = all_native_libs + .iter() + .filter(|l| relevant_lib(sess, l)) + .filter_map(|lib| { + let name = lib.name?; + match lib.kind { + NativeLibKind::StaticNoBundle + | NativeLibKind::Dylib + | NativeLibKind::Unspecified => { + if sess.target.target.options.is_like_msvc { + Some(format!("{}.lib", name)) + } else { + Some(format!("-l{}", name)) + } + } + NativeLibKind::Framework => { + // ld-only syntax, since there are no frameworks in MSVC + Some(format!("-framework {}", name)) + } + // These are included, no need to print them + NativeLibKind::StaticBundle | NativeLibKind::RawDylib => None, + } + }) + .collect(); + if !lib_args.is_empty() { + sess.note_without_error( + "Link against the following native artifacts when linking \ + against this static library. The order and any duplication \ + can be significant on some platforms.", + ); + // Prefix for greppability + sess.note_without_error(&format!("native-static-libs: {}", &lib_args.join(" "))); + } +} + +// Because windows-gnu target is meant to be self-contained for pure Rust code it bundles +// own mingw-w64 libraries. These libraries are usually not compatible with mingw-w64 +// installed in the system. This breaks many cases where Rust is mixed with other languages +// (e.g. *-sys crates). +// We prefer system mingw-w64 libraries if they are available to avoid this issue. +fn get_crt_libs_path(sess: &Session) -> Option<PathBuf> { + fn find_exe_in_path<P>(exe_name: P) -> Option<PathBuf> + where + P: AsRef<Path>, + { + for dir in env::split_paths(&env::var_os("PATH")?) { + let full_path = dir.join(&exe_name); + if full_path.is_file() { + return Some(fix_windows_verbatim_for_gcc(&full_path)); + } + } + None + } + + fn probe(sess: &Session) -> Option<PathBuf> { + if let (linker, LinkerFlavor::Gcc) = linker_and_flavor(&sess) { + let linker_path = if cfg!(windows) && linker.extension().is_none() { + linker.with_extension("exe") + } else { + linker + }; + if let Some(linker_path) = find_exe_in_path(linker_path) { + let mingw_arch = match &sess.target.target.arch { + x if x == "x86" => "i686", + x => x, + }; + let mingw_bits = &sess.target.target.target_pointer_width; + let mingw_dir = format!("{}-w64-mingw32", mingw_arch); + // Here we have path/bin/gcc but we need path/ + let mut path = linker_path; + path.pop(); + path.pop(); + // Loosely based on Clang MinGW driver + let probe_paths = vec![ + path.join(&mingw_dir).join("lib"), // Typical path + path.join(&mingw_dir).join("sys-root/mingw/lib"), // Rare path + path.join(format!( + "lib/mingw/tools/install/mingw{}/{}/lib", + &mingw_bits, &mingw_dir + )), // Chocolatey is creative + ]; + for probe_path in probe_paths { + if probe_path.join("crt2.o").exists() { + return Some(probe_path); + }; + } + }; + }; + None + } + + let mut system_library_path = sess.system_library_path.borrow_mut(); + match &*system_library_path { + Some(Some(compiler_libs_path)) => Some(compiler_libs_path.clone()), + Some(None) => None, + None => { + let path = probe(sess); + *system_library_path = Some(path.clone()); + path + } + } +} + +fn get_object_file_path(sess: &Session, name: &str, self_contained: bool) -> PathBuf { + // prefer system {,dll}crt2.o libs, see get_crt_libs_path comment for more details + if sess.opts.debugging_opts.link_self_contained.is_none() + && sess.target.target.llvm_target.contains("windows-gnu") + { + if let Some(compiler_libs_path) = get_crt_libs_path(sess) { + let file_path = compiler_libs_path.join(name); + if file_path.exists() { + return file_path; + } + } + } + let fs = sess.target_filesearch(PathKind::Native); + let file_path = fs.get_lib_path().join(name); + if file_path.exists() { + return file_path; + } + // Special directory with objects used only in self-contained linkage mode + if self_contained { + let file_path = fs.get_self_contained_lib_path().join(name); + if file_path.exists() { + return file_path; + } + } + for search_path in fs.search_paths() { + let file_path = search_path.dir.join(name); + if file_path.exists() { + return file_path; + } + } + PathBuf::from(name) +} + +fn exec_linker( + sess: &Session, + cmd: &Command, + out_filename: &Path, + tmpdir: &Path, +) -> io::Result<Output> { + // When attempting to spawn the linker we run a risk of blowing out the + // size limits for spawning a new process with respect to the arguments + // we pass on the command line. + // + // Here we attempt to handle errors from the OS saying "your list of + // arguments is too big" by reinvoking the linker again with an `@`-file + // that contains all the arguments. The theory is that this is then + // accepted on all linkers and the linker will read all its options out of + // there instead of looking at the command line. + if !cmd.very_likely_to_exceed_some_spawn_limit() { + match cmd.command().stdout(Stdio::piped()).stderr(Stdio::piped()).spawn() { + Ok(child) => { + let output = child.wait_with_output(); + flush_linked_file(&output, out_filename)?; + return output; + } + Err(ref e) if command_line_too_big(e) => { + info!("command line to linker was too big: {}", e); + } + Err(e) => return Err(e), + } + } + + info!("falling back to passing arguments to linker via an @-file"); + let mut cmd2 = cmd.clone(); + let mut args = String::new(); + for arg in cmd2.take_args() { + args.push_str( + &Escape { + arg: arg.to_str().unwrap(), + is_like_msvc: sess.target.target.options.is_like_msvc, + } + .to_string(), + ); + args.push_str("\n"); + } + let file = tmpdir.join("linker-arguments"); + let bytes = if sess.target.target.options.is_like_msvc { + let mut out = Vec::with_capacity((1 + args.len()) * 2); + // start the stream with a UTF-16 BOM + for c in std::iter::once(0xFEFF).chain(args.encode_utf16()) { + // encode in little endian + out.push(c as u8); + out.push((c >> 8) as u8); + } + out + } else { + args.into_bytes() + }; + fs::write(&file, &bytes)?; + cmd2.arg(format!("@{}", file.display())); + info!("invoking linker {:?}", cmd2); + let output = cmd2.output(); + flush_linked_file(&output, out_filename)?; + return output; + + #[cfg(unix)] + fn flush_linked_file(_: &io::Result<Output>, _: &Path) -> io::Result<()> { + Ok(()) + } + + #[cfg(windows)] + fn flush_linked_file( + command_output: &io::Result<Output>, + out_filename: &Path, + ) -> io::Result<()> { + // On Windows, under high I/O load, output buffers are sometimes not flushed, + // even long after process exit, causing nasty, non-reproducible output bugs. + // + // File::sync_all() calls FlushFileBuffers() down the line, which solves the problem. + // + // А full writeup of the original Chrome bug can be found at + // randomascii.wordpress.com/2018/02/25/compiler-bug-linker-bug-windows-kernel-bug/amp + + if let &Ok(ref out) = command_output { + if out.status.success() { + if let Ok(of) = fs::OpenOptions::new().write(true).open(out_filename) { + of.sync_all()?; + } + } + } + + Ok(()) + } + + #[cfg(unix)] + fn command_line_too_big(err: &io::Error) -> bool { + err.raw_os_error() == Some(::libc::E2BIG) + } + + #[cfg(windows)] + fn command_line_too_big(err: &io::Error) -> bool { + const ERROR_FILENAME_EXCED_RANGE: i32 = 206; + err.raw_os_error() == Some(ERROR_FILENAME_EXCED_RANGE) + } + + struct Escape<'a> { + arg: &'a str, + is_like_msvc: bool, + } + + impl<'a> fmt::Display for Escape<'a> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + if self.is_like_msvc { + // This is "documented" at + // https://docs.microsoft.com/en-us/cpp/build/reference/at-specify-a-linker-response-file + // + // Unfortunately there's not a great specification of the + // syntax I could find online (at least) but some local + // testing showed that this seemed sufficient-ish to catch + // at least a few edge cases. + write!(f, "\"")?; + for c in self.arg.chars() { + match c { + '"' => write!(f, "\\{}", c)?, + c => write!(f, "{}", c)?, + } + } + write!(f, "\"")?; + } else { + // This is documented at https://linux.die.net/man/1/ld, namely: + // + // > Options in file are separated by whitespace. A whitespace + // > character may be included in an option by surrounding the + // > entire option in either single or double quotes. Any + // > character (including a backslash) may be included by + // > prefixing the character to be included with a backslash. + // + // We put an argument on each line, so all we need to do is + // ensure the line is interpreted as one whole argument. + for c in self.arg.chars() { + match c { + '\\' | ' ' => write!(f, "\\{}", c)?, + c => write!(f, "{}", c)?, + } + } + } + Ok(()) + } + } +} + +fn link_output_kind(sess: &Session, crate_type: CrateType) -> LinkOutputKind { + let kind = match (crate_type, sess.crt_static(Some(crate_type)), sess.relocation_model()) { + (CrateType::Executable, false, RelocModel::Pic) => LinkOutputKind::DynamicPicExe, + (CrateType::Executable, false, _) => LinkOutputKind::DynamicNoPicExe, + (CrateType::Executable, true, RelocModel::Pic) => LinkOutputKind::StaticPicExe, + (CrateType::Executable, true, _) => LinkOutputKind::StaticNoPicExe, + (_, true, _) => LinkOutputKind::StaticDylib, + (_, false, _) => LinkOutputKind::DynamicDylib, + }; + + // Adjust the output kind to target capabilities. + let opts = &sess.target.target.options; + let pic_exe_supported = opts.position_independent_executables; + let static_pic_exe_supported = opts.static_position_independent_executables; + let static_dylib_supported = opts.crt_static_allows_dylibs; + match kind { + LinkOutputKind::DynamicPicExe if !pic_exe_supported => LinkOutputKind::DynamicNoPicExe, + LinkOutputKind::StaticPicExe if !static_pic_exe_supported => LinkOutputKind::StaticNoPicExe, + LinkOutputKind::StaticDylib if !static_dylib_supported => LinkOutputKind::DynamicDylib, + _ => kind, + } +} + +/// Whether we link to our own CRT objects instead of relying on gcc to pull them. +/// We only provide such support for a very limited number of targets. +fn crt_objects_fallback(sess: &Session, crate_type: CrateType) -> bool { + if let Some(self_contained) = sess.opts.debugging_opts.link_self_contained { + return self_contained; + } + + match sess.target.target.options.crt_objects_fallback { + // FIXME: Find a better heuristic for "native musl toolchain is available", + // based on host and linker path, for example. + // (https://github.com/rust-lang/rust/pull/71769#issuecomment-626330237). + Some(CrtObjectsFallback::Musl) => sess.crt_static(Some(crate_type)), + // FIXME: Find some heuristic for "native mingw toolchain is available", + // likely based on `get_crt_libs_path` (https://github.com/rust-lang/rust/pull/67429). + Some(CrtObjectsFallback::Mingw) => { + sess.host == sess.target.target && sess.target.target.target_vendor != "uwp" + } + // FIXME: Figure out cases in which WASM needs to link with a native toolchain. + Some(CrtObjectsFallback::Wasm) => true, + None => false, + } +} + +/// Add pre-link object files defined by the target spec. +fn add_pre_link_objects( + cmd: &mut dyn Linker, + sess: &Session, + link_output_kind: LinkOutputKind, + self_contained: bool, +) { + let opts = &sess.target.target.options; + let objects = + if self_contained { &opts.pre_link_objects_fallback } else { &opts.pre_link_objects }; + for obj in objects.get(&link_output_kind).iter().copied().flatten() { + cmd.add_object(&get_object_file_path(sess, obj, self_contained)); + } +} + +/// Add post-link object files defined by the target spec. +fn add_post_link_objects( + cmd: &mut dyn Linker, + sess: &Session, + link_output_kind: LinkOutputKind, + self_contained: bool, +) { + let opts = &sess.target.target.options; + let objects = + if self_contained { &opts.post_link_objects_fallback } else { &opts.post_link_objects }; + for obj in objects.get(&link_output_kind).iter().copied().flatten() { + cmd.add_object(&get_object_file_path(sess, obj, self_contained)); + } +} + +/// Add arbitrary "pre-link" args defined by the target spec or from command line. +/// FIXME: Determine where exactly these args need to be inserted. +fn add_pre_link_args(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavor) { + if let Some(args) = sess.target.target.options.pre_link_args.get(&flavor) { + cmd.args(args); + } + cmd.args(&sess.opts.debugging_opts.pre_link_args); +} + +/// Add a link script embedded in the target, if applicable. +fn add_link_script(cmd: &mut dyn Linker, sess: &Session, tmpdir: &Path, crate_type: CrateType) { + match (crate_type, &sess.target.target.options.link_script) { + (CrateType::Cdylib | CrateType::Executable, Some(script)) => { + if !sess.target.target.options.linker_is_gnu { + sess.fatal("can only use link script when linking with GNU-like linker"); + } + + let file_name = ["rustc", &sess.target.target.llvm_target, "linkfile.ld"].join("-"); + + let path = tmpdir.join(file_name); + if let Err(e) = fs::write(&path, script) { + sess.fatal(&format!("failed to write link script to {}: {}", path.display(), e)); + } + + cmd.arg("--script"); + cmd.arg(path); + } + _ => {} + } +} + +/// Add arbitrary "user defined" args defined from command line and by `#[link_args]` attributes. +/// FIXME: Determine where exactly these args need to be inserted. +fn add_user_defined_link_args( + cmd: &mut dyn Linker, + sess: &Session, + codegen_results: &CodegenResults, +) { + cmd.args(&sess.opts.cg.link_args); + cmd.args(&*codegen_results.crate_info.link_args); +} + +/// Add arbitrary "late link" args defined by the target spec. +/// FIXME: Determine where exactly these args need to be inserted. +fn add_late_link_args( + cmd: &mut dyn Linker, + sess: &Session, + flavor: LinkerFlavor, + crate_type: CrateType, + codegen_results: &CodegenResults, +) { + if let Some(args) = sess.target.target.options.late_link_args.get(&flavor) { + cmd.args(args); + } + let any_dynamic_crate = crate_type == CrateType::Dylib + || codegen_results.crate_info.dependency_formats.iter().any(|(ty, list)| { + *ty == crate_type && list.iter().any(|&linkage| linkage == Linkage::Dynamic) + }); + if any_dynamic_crate { + if let Some(args) = sess.target.target.options.late_link_args_dynamic.get(&flavor) { + cmd.args(args); + } + } else { + if let Some(args) = sess.target.target.options.late_link_args_static.get(&flavor) { + cmd.args(args); + } + } +} + +/// Add arbitrary "post-link" args defined by the target spec. +/// FIXME: Determine where exactly these args need to be inserted. +fn add_post_link_args(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavor) { + if let Some(args) = sess.target.target.options.post_link_args.get(&flavor) { + cmd.args(args); + } +} + +/// Add object files containing code from the current crate. +fn add_local_crate_regular_objects(cmd: &mut dyn Linker, codegen_results: &CodegenResults) { + for obj in codegen_results.modules.iter().filter_map(|m| m.object.as_ref()) { + cmd.add_object(obj); + } +} + +/// Add object files for allocator code linked once for the whole crate tree. +fn add_local_crate_allocator_objects(cmd: &mut dyn Linker, codegen_results: &CodegenResults) { + if let Some(obj) = codegen_results.allocator_module.as_ref().and_then(|m| m.object.as_ref()) { + cmd.add_object(obj); + } +} + +/// Add object files containing metadata for the current crate. +fn add_local_crate_metadata_objects( + cmd: &mut dyn Linker, + crate_type: CrateType, + codegen_results: &CodegenResults, +) { + // When linking a dynamic library, we put the metadata into a section of the + // executable. This metadata is in a separate object file from the main + // object file, so we link that in here. + if crate_type == CrateType::Dylib || crate_type == CrateType::ProcMacro { + if let Some(obj) = codegen_results.metadata_module.as_ref().and_then(|m| m.object.as_ref()) + { + cmd.add_object(obj); + } + } +} + +/// Link native libraries corresponding to the current crate and all libraries corresponding to +/// all its dependency crates. +/// FIXME: Consider combining this with the functions above adding object files for the local crate. +fn link_local_crate_native_libs_and_dependent_crate_libs<'a, B: ArchiveBuilder<'a>>( + cmd: &mut dyn Linker, + sess: &'a Session, + crate_type: CrateType, + codegen_results: &CodegenResults, + tmpdir: &Path, +) { + // Take careful note of the ordering of the arguments we pass to the linker + // here. Linkers will assume that things on the left depend on things to the + // right. Things on the right cannot depend on things on the left. This is + // all formally implemented in terms of resolving symbols (libs on the right + // resolve unknown symbols of libs on the left, but not vice versa). + // + // For this reason, we have organized the arguments we pass to the linker as + // such: + // + // 1. The local object that LLVM just generated + // 2. Local native libraries + // 3. Upstream rust libraries + // 4. Upstream native libraries + // + // The rationale behind this ordering is that those items lower down in the + // list can't depend on items higher up in the list. For example nothing can + // depend on what we just generated (e.g., that'd be a circular dependency). + // Upstream rust libraries are not allowed to depend on our local native + // libraries as that would violate the structure of the DAG, in that + // scenario they are required to link to them as well in a shared fashion. + // + // Note that upstream rust libraries may contain native dependencies as + // well, but they also can't depend on what we just started to add to the + // link line. And finally upstream native libraries can't depend on anything + // in this DAG so far because they're only dylibs and dylibs can only depend + // on other dylibs (e.g., other native deps). + // + // If -Zlink-native-libraries=false is set, then the assumption is that an + // external build system already has the native dependencies defined, and it + // will provide them to the linker itself. + if sess.opts.debugging_opts.link_native_libraries { + add_local_native_libraries(cmd, sess, codegen_results); + } + add_upstream_rust_crates::<B>(cmd, sess, codegen_results, crate_type, tmpdir); + if sess.opts.debugging_opts.link_native_libraries { + add_upstream_native_libraries(cmd, sess, codegen_results, crate_type); + } +} + +/// Add sysroot and other globally set directories to the directory search list. +fn add_library_search_dirs(cmd: &mut dyn Linker, sess: &Session, self_contained: bool) { + // Prefer system mingw-w64 libs, see get_crt_libs_path comment for more details. + if sess.opts.debugging_opts.link_self_contained.is_none() + && cfg!(windows) + && sess.target.target.llvm_target.contains("windows-gnu") + { + if let Some(compiler_libs_path) = get_crt_libs_path(sess) { + cmd.include_path(&compiler_libs_path); + } + } + + // The default library location, we need this to find the runtime. + // The location of crates will be determined as needed. + let lib_path = sess.target_filesearch(PathKind::All).get_lib_path(); + cmd.include_path(&fix_windows_verbatim_for_gcc(&lib_path)); + + // Special directory with libraries used only in self-contained linkage mode + if self_contained { + let lib_path = sess.target_filesearch(PathKind::All).get_self_contained_lib_path(); + cmd.include_path(&fix_windows_verbatim_for_gcc(&lib_path)); + } +} + +/// Add options making relocation sections in the produced ELF files read-only +/// and suppressing lazy binding. +fn add_relro_args(cmd: &mut dyn Linker, sess: &Session) { + match sess.opts.debugging_opts.relro_level.unwrap_or(sess.target.target.options.relro_level) { + RelroLevel::Full => cmd.full_relro(), + RelroLevel::Partial => cmd.partial_relro(), + RelroLevel::Off => cmd.no_relro(), + RelroLevel::None => {} + } +} + +/// Add library search paths used at runtime by dynamic linkers. +fn add_rpath_args( + cmd: &mut dyn Linker, + sess: &Session, + codegen_results: &CodegenResults, + out_filename: &Path, +) { + // FIXME (#2397): At some point we want to rpath our guesses as to + // where extern libraries might live, based on the + // addl_lib_search_paths + if sess.opts.cg.rpath { + let target_triple = sess.opts.target_triple.triple(); + let mut get_install_prefix_lib_path = || { + let install_prefix = option_env!("CFG_PREFIX").expect("CFG_PREFIX"); + let tlib = filesearch::relative_target_lib_path(&sess.sysroot, target_triple); + let mut path = PathBuf::from(install_prefix); + path.push(&tlib); + + path + }; + let mut rpath_config = RPathConfig { + used_crates: &codegen_results.crate_info.used_crates_dynamic, + out_filename: out_filename.to_path_buf(), + has_rpath: sess.target.target.options.has_rpath, + is_like_osx: sess.target.target.options.is_like_osx, + linker_is_gnu: sess.target.target.options.linker_is_gnu, + get_install_prefix_lib_path: &mut get_install_prefix_lib_path, + }; + cmd.args(&rpath::get_rpath_flags(&mut rpath_config)); + } +} + +/// Produce the linker command line containing linker path and arguments. +/// `NO-OPT-OUT` marks the arguments that cannot be removed from the command line +/// by the user without creating a custom target specification. +/// `OBJECT-FILES` specify whether the arguments can add object files. +/// `CUSTOMIZATION-POINT` means that arbitrary arguments defined by the user +/// or by the target spec can be inserted here. +/// `AUDIT-ORDER` - need to figure out whether the option is order-dependent or not. +fn linker_with_args<'a, B: ArchiveBuilder<'a>>( + path: &Path, + flavor: LinkerFlavor, + sess: &'a Session, + crate_type: CrateType, + tmpdir: &Path, + out_filename: &Path, + codegen_results: &CodegenResults, + target_cpu: &str, +) -> Command { + let crt_objects_fallback = crt_objects_fallback(sess, crate_type); + let base_cmd = get_linker(sess, path, flavor, crt_objects_fallback); + // FIXME: Move `/LIBPATH` addition for uwp targets from the linker construction + // to the linker args construction. + assert!(base_cmd.get_args().is_empty() || sess.target.target.target_vendor == "uwp"); + let cmd = &mut *codegen_results.linker_info.to_linker(base_cmd, &sess, flavor, target_cpu); + let link_output_kind = link_output_kind(sess, crate_type); + + // NO-OPT-OUT, OBJECT-FILES-MAYBE, CUSTOMIZATION-POINT + add_pre_link_args(cmd, sess, flavor); + + // NO-OPT-OUT + add_link_script(cmd, sess, tmpdir, crate_type); + + // NO-OPT-OUT, OBJECT-FILES-NO, AUDIT-ORDER + if sess.target.target.options.is_like_fuchsia && crate_type == CrateType::Executable { + let prefix = if sess.opts.debugging_opts.sanitizer.contains(SanitizerSet::ADDRESS) { + "asan/" + } else { + "" + }; + cmd.arg(format!("--dynamic-linker={}ld.so.1", prefix)); + } + + // NO-OPT-OUT, OBJECT-FILES-NO, AUDIT-ORDER + if sess.target.target.options.eh_frame_header { + cmd.add_eh_frame_header(); + } + + // NO-OPT-OUT, OBJECT-FILES-NO + if crt_objects_fallback { + cmd.no_crt_objects(); + } + + // NO-OPT-OUT, OBJECT-FILES-YES + add_pre_link_objects(cmd, sess, link_output_kind, crt_objects_fallback); + + // NO-OPT-OUT, OBJECT-FILES-NO, AUDIT-ORDER + if sess.target.target.options.is_like_emscripten { + cmd.arg("-s"); + cmd.arg(if sess.panic_strategy() == PanicStrategy::Abort { + "DISABLE_EXCEPTION_CATCHING=1" + } else { + "DISABLE_EXCEPTION_CATCHING=0" + }); + } + + // OBJECT-FILES-YES, AUDIT-ORDER + link_sanitizers(sess, crate_type, cmd); + + // OBJECT-FILES-NO, AUDIT-ORDER + // Linker plugins should be specified early in the list of arguments + // FIXME: How "early" exactly? + cmd.linker_plugin_lto(); + + // NO-OPT-OUT, OBJECT-FILES-NO, AUDIT-ORDER + // FIXME: Order-dependent, at least relatively to other args adding searh directories. + add_library_search_dirs(cmd, sess, crt_objects_fallback); + + // OBJECT-FILES-YES + add_local_crate_regular_objects(cmd, codegen_results); + + // NO-OPT-OUT, OBJECT-FILES-NO, AUDIT-ORDER + cmd.output_filename(out_filename); + + // OBJECT-FILES-NO, AUDIT-ORDER + if crate_type == CrateType::Executable && sess.target.target.options.is_like_windows { + if let Some(ref s) = codegen_results.windows_subsystem { + cmd.subsystem(s); + } + } + + // NO-OPT-OUT, OBJECT-FILES-NO, AUDIT-ORDER + // If we're building something like a dynamic library then some platforms + // need to make sure that all symbols are exported correctly from the + // dynamic library. + cmd.export_symbols(tmpdir, crate_type); + + // OBJECT-FILES-YES + add_local_crate_metadata_objects(cmd, crate_type, codegen_results); + + // OBJECT-FILES-YES + add_local_crate_allocator_objects(cmd, codegen_results); + + // OBJECT-FILES-NO, AUDIT-ORDER + // FIXME: Order dependent, applies to the following objects. Where should it be placed? + // Try to strip as much out of the generated object by removing unused + // sections if possible. See more comments in linker.rs + if sess.opts.cg.link_dead_code != Some(true) { + let keep_metadata = crate_type == CrateType::Dylib; + cmd.gc_sections(keep_metadata); + } + + // NO-OPT-OUT, OBJECT-FILES-NO, AUDIT-ORDER + cmd.set_output_kind(link_output_kind, out_filename); + + // OBJECT-FILES-NO, AUDIT-ORDER + add_relro_args(cmd, sess); + + // OBJECT-FILES-NO, AUDIT-ORDER + // Pass optimization flags down to the linker. + cmd.optimize(); + + // OBJECT-FILES-NO, AUDIT-ORDER + // Pass debuginfo and strip flags down to the linker. + cmd.debuginfo(sess.opts.debugging_opts.strip); + + // OBJECT-FILES-NO, AUDIT-ORDER + // We want to prevent the compiler from accidentally leaking in any system libraries, + // so by default we tell linkers not to link to any default libraries. + if !sess.opts.cg.default_linker_libraries && sess.target.target.options.no_default_libraries { + cmd.no_default_libraries(); + } + + // OBJECT-FILES-YES + link_local_crate_native_libs_and_dependent_crate_libs::<B>( + cmd, + sess, + crate_type, + codegen_results, + tmpdir, + ); + + // OBJECT-FILES-NO, AUDIT-ORDER + if sess.opts.cg.profile_generate.enabled() || sess.opts.debugging_opts.instrument_coverage { + cmd.pgo_gen(); + } + + // OBJECT-FILES-NO, AUDIT-ORDER + if sess.opts.cg.control_flow_guard != CFGuard::Disabled { + cmd.control_flow_guard(); + } + + // OBJECT-FILES-NO, AUDIT-ORDER + add_rpath_args(cmd, sess, codegen_results, out_filename); + + // OBJECT-FILES-MAYBE, CUSTOMIZATION-POINT + add_user_defined_link_args(cmd, sess, codegen_results); + + // NO-OPT-OUT, OBJECT-FILES-NO, AUDIT-ORDER + cmd.finalize(); + + // NO-OPT-OUT, OBJECT-FILES-MAYBE, CUSTOMIZATION-POINT + add_late_link_args(cmd, sess, flavor, crate_type, codegen_results); + + // NO-OPT-OUT, OBJECT-FILES-YES + add_post_link_objects(cmd, sess, link_output_kind, crt_objects_fallback); + + // NO-OPT-OUT, OBJECT-FILES-MAYBE, CUSTOMIZATION-POINT + add_post_link_args(cmd, sess, flavor); + + cmd.take_cmd() +} + +// # Native library linking +// +// User-supplied library search paths (-L on the command line). These are +// the same paths used to find Rust crates, so some of them may have been +// added already by the previous crate linking code. This only allows them +// to be found at compile time so it is still entirely up to outside +// forces to make sure that library can be found at runtime. +// +// Also note that the native libraries linked here are only the ones located +// in the current crate. Upstream crates with native library dependencies +// may have their native library pulled in above. +fn add_local_native_libraries( + cmd: &mut dyn Linker, + sess: &Session, + codegen_results: &CodegenResults, +) { + let filesearch = sess.target_filesearch(PathKind::All); + for search_path in filesearch.search_paths() { + match search_path.kind { + PathKind::Framework => { + cmd.framework_path(&search_path.dir); + } + _ => { + cmd.include_path(&fix_windows_verbatim_for_gcc(&search_path.dir)); + } + } + } + + let relevant_libs = + codegen_results.crate_info.used_libraries.iter().filter(|l| relevant_lib(sess, l)); + + let search_path = archive_search_paths(sess); + for lib in relevant_libs { + let name = match lib.name { + Some(l) => l, + None => continue, + }; + match lib.kind { + NativeLibKind::Dylib | NativeLibKind::Unspecified => cmd.link_dylib(name), + NativeLibKind::Framework => cmd.link_framework(name), + NativeLibKind::StaticNoBundle => cmd.link_staticlib(name), + NativeLibKind::StaticBundle => cmd.link_whole_staticlib(name, &search_path), + NativeLibKind::RawDylib => { + // FIXME(#58713): Proper handling for raw dylibs. + bug!("raw_dylib feature not yet implemented"); + } + } + } +} + +// # Rust Crate linking +// +// Rust crates are not considered at all when creating an rlib output. All +// dependencies will be linked when producing the final output (instead of +// the intermediate rlib version) +fn add_upstream_rust_crates<'a, B: ArchiveBuilder<'a>>( + cmd: &mut dyn Linker, + sess: &'a Session, + codegen_results: &CodegenResults, + crate_type: CrateType, + tmpdir: &Path, +) { + // All of the heavy lifting has previously been accomplished by the + // dependency_format module of the compiler. This is just crawling the + // output of that module, adding crates as necessary. + // + // Linking to a rlib involves just passing it to the linker (the linker + // will slurp up the object files inside), and linking to a dynamic library + // involves just passing the right -l flag. + + let (_, data) = codegen_results + .crate_info + .dependency_formats + .iter() + .find(|(ty, _)| *ty == crate_type) + .expect("failed to find crate type in dependency format list"); + + // Invoke get_used_crates to ensure that we get a topological sorting of + // crates. + let deps = &codegen_results.crate_info.used_crates_dynamic; + + // There's a few internal crates in the standard library (aka libcore and + // libstd) which actually have a circular dependence upon one another. This + // currently arises through "weak lang items" where libcore requires things + // like `rust_begin_unwind` but libstd ends up defining it. To get this + // circular dependence to work correctly in all situations we'll need to be + // sure to correctly apply the `--start-group` and `--end-group` options to + // GNU linkers, otherwise if we don't use any other symbol from the standard + // library it'll get discarded and the whole application won't link. + // + // In this loop we're calculating the `group_end`, after which crate to + // pass `--end-group` and `group_start`, before which crate to pass + // `--start-group`. We currently do this by passing `--end-group` after + // the first crate (when iterating backwards) that requires a lang item + // defined somewhere else. Once that's set then when we've defined all the + // necessary lang items we'll pass `--start-group`. + // + // Note that this isn't amazing logic for now but it should do the trick + // for the current implementation of the standard library. + let mut group_end = None; + let mut group_start = None; + // Crates available for linking thus far. + let mut available = FxHashSet::default(); + // Crates required to satisfy dependencies discovered so far. + let mut required = FxHashSet::default(); + + let info = &codegen_results.crate_info; + for &(cnum, _) in deps.iter().rev() { + if let Some(missing) = info.missing_lang_items.get(&cnum) { + let missing_crates = missing.iter().map(|i| info.lang_item_to_crate.get(i).copied()); + required.extend(missing_crates); + } + + required.insert(Some(cnum)); + available.insert(Some(cnum)); + + if required.len() > available.len() && group_end.is_none() { + group_end = Some(cnum); + } + if required.len() == available.len() && group_end.is_some() { + group_start = Some(cnum); + break; + } + } + + // If we didn't end up filling in all lang items from upstream crates then + // we'll be filling it in with our crate. This probably means we're the + // standard library itself, so skip this for now. + if group_end.is_some() && group_start.is_none() { + group_end = None; + } + + let mut compiler_builtins = None; + + for &(cnum, _) in deps.iter() { + if group_start == Some(cnum) { + cmd.group_start(); + } + + // We may not pass all crates through to the linker. Some crates may + // appear statically in an existing dylib, meaning we'll pick up all the + // symbols from the dylib. + let src = &codegen_results.crate_info.used_crate_source[&cnum]; + match data[cnum.as_usize() - 1] { + _ if codegen_results.crate_info.profiler_runtime == Some(cnum) => { + add_static_crate::<B>(cmd, sess, codegen_results, tmpdir, crate_type, cnum); + } + // compiler-builtins are always placed last to ensure that they're + // linked correctly. + _ if codegen_results.crate_info.compiler_builtins == Some(cnum) => { + assert!(compiler_builtins.is_none()); + compiler_builtins = Some(cnum); + } + Linkage::NotLinked | Linkage::IncludedFromDylib => {} + Linkage::Static => { + add_static_crate::<B>(cmd, sess, codegen_results, tmpdir, crate_type, cnum); + } + Linkage::Dynamic => add_dynamic_crate(cmd, sess, &src.dylib.as_ref().unwrap().0), + } + + if group_end == Some(cnum) { + cmd.group_end(); + } + } + + // compiler-builtins are always placed last to ensure that they're + // linked correctly. + // We must always link the `compiler_builtins` crate statically. Even if it + // was already "included" in a dylib (e.g., `libstd` when `-C prefer-dynamic` + // is used) + if let Some(cnum) = compiler_builtins { + add_static_crate::<B>(cmd, sess, codegen_results, tmpdir, crate_type, cnum); + } + + // Converts a library file-stem into a cc -l argument + fn unlib<'a>(config: &config::Config, stem: &'a str) -> &'a str { + if stem.starts_with("lib") && !config.target.options.is_like_windows { + &stem[3..] + } else { + stem + } + } + + // Adds the static "rlib" versions of all crates to the command line. + // There's a bit of magic which happens here specifically related to LTO and + // dynamic libraries. Specifically: + // + // * For LTO, we remove upstream object files. + // * For dylibs we remove metadata and bytecode from upstream rlibs + // + // When performing LTO, almost(*) all of the bytecode from the upstream + // libraries has already been included in our object file output. As a + // result we need to remove the object files in the upstream libraries so + // the linker doesn't try to include them twice (or whine about duplicate + // symbols). We must continue to include the rest of the rlib, however, as + // it may contain static native libraries which must be linked in. + // + // (*) Crates marked with `#![no_builtins]` don't participate in LTO and + // their bytecode wasn't included. The object files in those libraries must + // still be passed to the linker. + // + // When making a dynamic library, linkers by default don't include any + // object files in an archive if they're not necessary to resolve the link. + // We basically want to convert the archive (rlib) to a dylib, though, so we + // *do* want everything included in the output, regardless of whether the + // linker thinks it's needed or not. As a result we must use the + // --whole-archive option (or the platform equivalent). When using this + // option the linker will fail if there are non-objects in the archive (such + // as our own metadata and/or bytecode). All in all, for rlibs to be + // entirely included in dylibs, we need to remove all non-object files. + // + // Note, however, that if we're not doing LTO or we're not producing a dylib + // (aka we're making an executable), we can just pass the rlib blindly to + // the linker (fast) because it's fine if it's not actually included as + // we're at the end of the dependency chain. + fn add_static_crate<'a, B: ArchiveBuilder<'a>>( + cmd: &mut dyn Linker, + sess: &'a Session, + codegen_results: &CodegenResults, + tmpdir: &Path, + crate_type: CrateType, + cnum: CrateNum, + ) { + let src = &codegen_results.crate_info.used_crate_source[&cnum]; + let cratepath = &src.rlib.as_ref().unwrap().0; + + // See the comment above in `link_staticlib` and `link_rlib` for why if + // there's a static library that's not relevant we skip all object + // files. + let native_libs = &codegen_results.crate_info.native_libraries[&cnum]; + let skip_native = native_libs + .iter() + .any(|lib| lib.kind == NativeLibKind::StaticBundle && !relevant_lib(sess, lib)); + + if (!are_upstream_rust_objects_already_included(sess) + || ignored_for_lto(sess, &codegen_results.crate_info, cnum)) + && crate_type != CrateType::Dylib + && !skip_native + { + cmd.link_rlib(&fix_windows_verbatim_for_gcc(cratepath)); + return; + } + + let dst = tmpdir.join(cratepath.file_name().unwrap()); + let name = cratepath.file_name().unwrap().to_str().unwrap(); + let name = &name[3..name.len() - 5]; // chop off lib/.rlib + + sess.prof.generic_activity_with_arg("link_altering_rlib", name).run(|| { + let mut archive = <B as ArchiveBuilder>::new(sess, &dst, Some(cratepath)); + archive.update_symbols(); + + let mut any_objects = false; + for f in archive.src_files() { + if f == METADATA_FILENAME { + archive.remove_file(&f); + continue; + } + + let canonical = f.replace("-", "_"); + let canonical_name = name.replace("-", "_"); + + let is_rust_object = + canonical.starts_with(&canonical_name) && looks_like_rust_object_file(&f); + + // If we've been requested to skip all native object files + // (those not generated by the rust compiler) then we can skip + // this file. See above for why we may want to do this. + let skip_because_cfg_say_so = skip_native && !is_rust_object; + + // If we're performing LTO and this is a rust-generated object + // file, then we don't need the object file as it's part of the + // LTO module. Note that `#![no_builtins]` is excluded from LTO, + // though, so we let that object file slide. + let skip_because_lto = are_upstream_rust_objects_already_included(sess) + && is_rust_object + && (sess.target.target.options.no_builtins + || !codegen_results.crate_info.is_no_builtins.contains(&cnum)); + + if skip_because_cfg_say_so || skip_because_lto { + archive.remove_file(&f); + } else { + any_objects = true; + } + } + + if !any_objects { + return; + } + archive.build(); + + // If we're creating a dylib, then we need to include the + // whole of each object in our archive into that artifact. This is + // because a `dylib` can be reused as an intermediate artifact. + // + // Note, though, that we don't want to include the whole of a + // compiler-builtins crate (e.g., compiler-rt) because it'll get + // repeatedly linked anyway. + if crate_type == CrateType::Dylib + && codegen_results.crate_info.compiler_builtins != Some(cnum) + { + cmd.link_whole_rlib(&fix_windows_verbatim_for_gcc(&dst)); + } else { + cmd.link_rlib(&fix_windows_verbatim_for_gcc(&dst)); + } + }); + } + + // Same thing as above, but for dynamic crates instead of static crates. + fn add_dynamic_crate(cmd: &mut dyn Linker, sess: &Session, cratepath: &Path) { + // Just need to tell the linker about where the library lives and + // what its name is + let parent = cratepath.parent(); + if let Some(dir) = parent { + cmd.include_path(&fix_windows_verbatim_for_gcc(dir)); + } + let filestem = cratepath.file_stem().unwrap().to_str().unwrap(); + cmd.link_rust_dylib( + Symbol::intern(&unlib(&sess.target, filestem)), + parent.unwrap_or(Path::new("")), + ); + } +} + +// Link in all of our upstream crates' native dependencies. Remember that +// all of these upstream native dependencies are all non-static +// dependencies. We've got two cases then: +// +// 1. The upstream crate is an rlib. In this case we *must* link in the +// native dependency because the rlib is just an archive. +// +// 2. The upstream crate is a dylib. In order to use the dylib, we have to +// have the dependency present on the system somewhere. Thus, we don't +// gain a whole lot from not linking in the dynamic dependency to this +// crate as well. +// +// The use case for this is a little subtle. In theory the native +// dependencies of a crate are purely an implementation detail of the crate +// itself, but the problem arises with generic and inlined functions. If a +// generic function calls a native function, then the generic function must +// be instantiated in the target crate, meaning that the native symbol must +// also be resolved in the target crate. +fn add_upstream_native_libraries( + cmd: &mut dyn Linker, + sess: &Session, + codegen_results: &CodegenResults, + crate_type: CrateType, +) { + // Be sure to use a topological sorting of crates because there may be + // interdependencies between native libraries. When passing -nodefaultlibs, + // for example, almost all native libraries depend on libc, so we have to + // make sure that's all the way at the right (liblibc is near the base of + // the dependency chain). + // + // This passes RequireStatic, but the actual requirement doesn't matter, + // we're just getting an ordering of crate numbers, we're not worried about + // the paths. + let (_, data) = codegen_results + .crate_info + .dependency_formats + .iter() + .find(|(ty, _)| *ty == crate_type) + .expect("failed to find crate type in dependency format list"); + + let crates = &codegen_results.crate_info.used_crates_static; + for &(cnum, _) in crates { + for lib in codegen_results.crate_info.native_libraries[&cnum].iter() { + let name = match lib.name { + Some(l) => l, + None => continue, + }; + if !relevant_lib(sess, &lib) { + continue; + } + match lib.kind { + NativeLibKind::Dylib | NativeLibKind::Unspecified => cmd.link_dylib(name), + NativeLibKind::Framework => cmd.link_framework(name), + NativeLibKind::StaticNoBundle => { + // Link "static-nobundle" native libs only if the crate they originate from + // is being linked statically to the current crate. If it's linked dynamically + // or is an rlib already included via some other dylib crate, the symbols from + // native libs will have already been included in that dylib. + if data[cnum.as_usize() - 1] == Linkage::Static { + cmd.link_staticlib(name) + } + } + // ignore statically included native libraries here as we've + // already included them when we included the rust library + // previously + NativeLibKind::StaticBundle => {} + NativeLibKind::RawDylib => { + // FIXME(#58713): Proper handling for raw dylibs. + bug!("raw_dylib feature not yet implemented"); + } + } + } + } +} + +fn relevant_lib(sess: &Session, lib: &NativeLib) -> bool { + match lib.cfg { + Some(ref cfg) => rustc_attr::cfg_matches(cfg, &sess.parse_sess, None), + None => true, + } +} + +fn are_upstream_rust_objects_already_included(sess: &Session) -> bool { + match sess.lto() { + config::Lto::Fat => true, + config::Lto::Thin => { + // If we defer LTO to the linker, we haven't run LTO ourselves, so + // any upstream object files have not been copied yet. + !sess.opts.cg.linker_plugin_lto.enabled() + } + config::Lto::No | config::Lto::ThinLocal => false, + } +} |