1 //! Shim which is passed to Cargo as "rustc" when running the bootstrap.
3 //! This shim will take care of some various tasks that our build process
4 //! requires that Cargo can't quite do through normal configuration:
6 //! 1. When compiling build scripts and build dependencies, we need a guaranteed
7 //! full standard library available. The only compiler which actually has
8 //! this is the snapshot, so we detect this situation and always compile with
9 //! the snapshot compiler.
10 //! 2. We pass a bunch of `--cfg` and other flags based on what we're compiling
11 //! (and this slightly differs based on a whether we're using a snapshot or
12 //! not), so we do that all here.
14 //! This may one day be replaced by RUSTFLAGS, but the dynamic nature of
15 //! switching compilers for the bootstrap and for build scripts will probably
16 //! never get replaced.
18 include!("../dylib_util.rs");
21 use std::path::PathBuf;
22 use std::process::{Child, Command};
23 use std::str::FromStr;
24 use std::time::Instant;
27 let args = env::args_os().skip(1).collect::<Vec<_>>();
28 let arg = |name| args.windows(2).find(|args| args[0] == name).and_then(|args| args[1].to_str());
30 // Detect whether or not we're a build script depending on whether --target
31 // is passed (a bit janky...)
32 let target = arg("--target");
33 let version = args.iter().find(|w| &**w == "-vV");
35 let verbose = match env::var("RUSTC_VERBOSE") {
36 Ok(s) => usize::from_str(&s).expect("RUSTC_VERBOSE should be an integer"),
40 // Use a different compiler for build scripts, since there may not yet be a
41 // libstd for the real compiler to use. However, if Cargo is attempting to
42 // determine the version of the compiler, the real compiler needs to be
43 // used. Currently, these two states are differentiated based on whether
44 // --target and -vV is/isn't passed.
45 let (rustc, libdir) = if target.is_none() && version.is_none() {
46 ("RUSTC_SNAPSHOT", "RUSTC_SNAPSHOT_LIBDIR")
48 ("RUSTC_REAL", "RUSTC_LIBDIR")
50 let stage = env::var("RUSTC_STAGE").expect("RUSTC_STAGE was not set");
51 let sysroot = env::var_os("RUSTC_SYSROOT").expect("RUSTC_SYSROOT was not set");
52 let on_fail = env::var_os("RUSTC_ON_FAIL").map(Command::new);
54 let rustc = env::var_os(rustc).unwrap_or_else(|| panic!("{:?} was not set", rustc));
55 let libdir = env::var_os(libdir).unwrap_or_else(|| panic!("{:?} was not set", libdir));
56 let mut dylib_path = dylib_path();
57 dylib_path.insert(0, PathBuf::from(&libdir));
59 let mut cmd = Command::new(rustc);
60 cmd.args(&args).env(dylib_path_var(), env::join_paths(&dylib_path).unwrap());
62 // Get the name of the crate we're compiling, if any.
63 let crate_name = arg("--crate-name");
65 if let Some(crate_name) = crate_name {
66 if let Some(target) = env::var_os("RUSTC_TIME") {
68 || target.into_string().unwrap().split(',').any(|c| c.trim() == crate_name)
70 cmd.arg("-Ztime-passes");
75 // Print backtrace in case of ICE
76 if env::var("RUSTC_BACKTRACE_ON_ICE").is_ok() && env::var("RUST_BACKTRACE").is_err() {
77 cmd.env("RUST_BACKTRACE", "1");
80 if let Ok(lint_flags) = env::var("RUSTC_LINT_FLAGS") {
81 cmd.args(lint_flags.split_whitespace());
85 // The stage0 compiler has a special sysroot distinct from what we
86 // actually downloaded, so we just always pass the `--sysroot` option,
87 // unless one is already set.
88 if !args.iter().any(|arg| arg == "--sysroot") {
89 cmd.arg("--sysroot").arg(&sysroot);
92 // If we're compiling specifically the `panic_abort` crate then we pass
93 // the `-C panic=abort` option. Note that we do not do this for any
94 // other crate intentionally as this is the only crate for now that we
95 // ship with panic=abort.
97 // This... is a bit of a hack how we detect this. Ideally this
98 // information should be encoded in the crate I guess? Would likely
99 // require an RFC amendment to RFC 1513, however.
100 if crate_name == Some("panic_abort") {
101 cmd.arg("-C").arg("panic=abort");
104 // `-Ztls-model=initial-exec` must not be applied to proc-macros, see
105 // issue https://github.com/rust-lang/rust/issues/100530
106 if env::var("RUSTC_TLS_MODEL_INITIAL_EXEC").is_ok()
107 && arg("--crate-type") != Some("proc-macro")
108 && !matches!(crate_name, Some("proc_macro2" | "quote" | "syn" | "synstructure"))
110 cmd.arg("-Ztls-model=initial-exec");
113 // FIXME(rust-lang/cargo#5754) we shouldn't be using special env vars
114 // here, but rather Cargo should know what flags to pass rustc itself.
116 // Override linker if necessary.
117 if let Ok(host_linker) = env::var("RUSTC_HOST_LINKER") {
118 cmd.arg(format!("-Clinker={}", host_linker));
120 if env::var_os("RUSTC_HOST_FUSE_LD_LLD").is_some() {
121 cmd.arg("-Clink-args=-fuse-ld=lld");
124 if let Ok(s) = env::var("RUSTC_HOST_CRT_STATIC") {
126 cmd.arg("-C").arg("target-feature=+crt-static");
129 cmd.arg("-C").arg("target-feature=-crt-static");
133 // Cargo doesn't pass RUSTFLAGS to proc_macros:
134 // https://github.com/rust-lang/cargo/issues/4423
135 // Thus, if we are on stage 0, we explicitly set `--cfg=bootstrap`.
136 // We also declare that the flag is expected, which we need to do to not
137 // get warnings about it being unexpected.
139 cmd.arg("--cfg=bootstrap");
141 cmd.arg("-Zunstable-options");
142 cmd.arg("--check-cfg=values(bootstrap)");
145 if let Ok(map) = env::var("RUSTC_DEBUGINFO_MAP") {
146 cmd.arg("--remap-path-prefix").arg(&map);
149 // Force all crates compiled by this compiler to (a) be unstable and (b)
150 // allow the `rustc_private` feature to link to other unstable crates
151 // also in the sysroot. We also do this for host crates, since those
152 // may be proc macros, in which case we might ship them.
153 if env::var_os("RUSTC_FORCE_UNSTABLE").is_some() && (stage != "0" || target.is_some()) {
154 cmd.arg("-Z").arg("force-unstable-if-unmarked");
157 // allow-features is handled from within this rustc wrapper because of
158 // issues with build scripts. Some packages use build scripts to
159 // dynamically detect if certain nightly features are available.
160 // There are different ways this causes problems:
162 // * rustix runs `rustc` on a small test program to see if the feature is
163 // available (and sets a `cfg` if it is). It does not honor
164 // CARGO_ENCODED_RUSTFLAGS.
165 // * proc-macro2 detects if `rustc -vV` says "nighty" or "dev" and enables
166 // nightly features. It will scan CARGO_ENCODED_RUSTFLAGS for
167 // -Zallow-features. Unfortunately CARGO_ENCODED_RUSTFLAGS is not set
168 // for build-dependencies when --target is used.
170 // The issues above means we can't just use RUSTFLAGS, and we can't use
171 // `cargo -Zallow-features=…`. Passing it through here ensures that it
172 // always gets set. Unfortunately that also means we need to enable more
173 // features than we really want (like those for proc-macro2), but there
174 // isn't much of a way around it.
176 // I think it is unfortunate that build scripts are doing this at all,
177 // since changes to nightly features can cause crates to break even if the
178 // user didn't want or care about the use of the nightly features. I think
179 // nightly features should be opt-in only. Unfortunately the dynamic
180 // checks are now too wide spread that we just need to deal with it.
182 // If you want to try to remove this, I suggest working with the crate
183 // authors to remove the dynamic checking. Another option is to pursue
184 // https://github.com/rust-lang/cargo/issues/11244 and
185 // https://github.com/rust-lang/cargo/issues/4423, which will likely be
186 // very difficult, but could help expose -Zallow-features into build
187 // scripts so they could try to honor them.
188 if let Ok(allow_features) = env::var("RUSTC_ALLOW_FEATURES") {
189 cmd.arg(format!("-Zallow-features={allow_features}"));
192 if let Ok(flags) = env::var("MAGIC_EXTRA_RUSTFLAGS") {
193 for flag in flags.split(' ') {
198 let is_test = args.iter().any(|a| a == "--test");
201 env::vars().filter(|(k, _)| k.starts_with("RUST") || k.starts_with("CARGO"));
202 let prefix = if is_test { "[RUSTC-SHIM] rustc --test" } else { "[RUSTC-SHIM] rustc" };
203 let prefix = match crate_name {
204 Some(crate_name) => format!("{} {}", prefix, crate_name),
205 None => prefix.to_string(),
207 for (i, (k, v)) in rust_env_vars.enumerate() {
208 eprintln!("{} env[{}]: {:?}={:?}", prefix, i, k, v);
210 eprintln!("{} working directory: {}", prefix, env::current_dir().unwrap().display());
212 "{} command: {:?}={:?} {:?}",
215 env::join_paths(&dylib_path).unwrap(),
218 eprintln!("{} sysroot: {:?}", prefix, sysroot);
219 eprintln!("{} libdir: {:?}", prefix, libdir);
222 let start = Instant::now();
223 let (child, status) = {
224 let errmsg = format!("\nFailed to run:\n{:?}\n-------------", cmd);
225 let mut child = cmd.spawn().expect(&errmsg);
226 let status = child.wait().expect(&errmsg);
230 if env::var_os("RUSTC_PRINT_STEP_TIMINGS").is_some()
231 || env::var_os("RUSTC_PRINT_STEP_RUSAGE").is_some()
233 if let Some(crate_name) = crate_name {
234 let dur = start.elapsed();
235 // If the user requested resource usage data, then
236 // include that in addition to the timing output.
238 env::var_os("RUSTC_PRINT_STEP_RUSAGE").and_then(|_| format_rusage_data(child));
240 "[RUSTC-TIMING] {} test:{} {}.{:03}{}{}",
245 if rusage_data.is_some() { " " } else { "" },
246 rusage_data.unwrap_or(String::new()),
251 if status.success() {
252 std::process::exit(0);
253 // note: everything below here is unreachable. do not put code that
254 // should run on success, after this block.
257 println!("\nDid not run successfully: {}\n{:?}\n-------------", status, cmd);
260 if let Some(mut on_fail) = on_fail {
261 on_fail.status().expect("Could not run the on_fail command");
264 // Preserve the exit code. In case of signal, exit with 0xfe since it's
265 // awkward to preserve this status in a cross-platform way.
266 match status.code() {
267 Some(i) => std::process::exit(i),
269 eprintln!("rustc exited with {}", status);
270 std::process::exit(0xfe);
275 #[cfg(all(not(unix), not(windows)))]
276 // In the future we can add this for more platforms
277 fn format_rusage_data(_child: Child) -> Option<String> {
282 fn format_rusage_data(child: Child) -> Option<String> {
283 use std::os::windows::io::AsRawHandle;
284 use winapi::um::{processthreadsapi, psapi, timezoneapi};
285 let handle = child.as_raw_handle();
286 macro_rules! try_bool {
294 let mut user_filetime = Default::default();
295 let mut user_time = Default::default();
296 let mut kernel_filetime = Default::default();
297 let mut kernel_time = Default::default();
298 let mut memory_counters = psapi::PROCESS_MEMORY_COUNTERS::default();
301 try_bool!(processthreadsapi::GetProcessTimes(
303 &mut Default::default(),
304 &mut Default::default(),
305 &mut kernel_filetime,
308 try_bool!(timezoneapi::FileTimeToSystemTime(&user_filetime, &mut user_time));
309 try_bool!(timezoneapi::FileTimeToSystemTime(&kernel_filetime, &mut kernel_time));
311 // Unlike on Linux with RUSAGE_CHILDREN, this will only return memory information for the process
312 // with the given handle and none of that process's children.
313 try_bool!(psapi::GetProcessMemoryInfo(
315 &mut memory_counters as *mut _ as _,
316 std::mem::size_of::<psapi::PROCESS_MEMORY_COUNTERS_EX>() as u32,
320 // Guide on interpreting these numbers:
321 // https://docs.microsoft.com/en-us/windows/win32/psapi/process-memory-usage-information
322 let peak_working_set = memory_counters.PeakWorkingSetSize / 1024;
323 let peak_page_file = memory_counters.PeakPagefileUsage / 1024;
324 let peak_paged_pool = memory_counters.QuotaPeakPagedPoolUsage / 1024;
325 let peak_nonpaged_pool = memory_counters.QuotaPeakNonPagedPoolUsage / 1024;
327 "user: {USER_SEC}.{USER_USEC:03} \
328 sys: {SYS_SEC}.{SYS_USEC:03} \
329 peak working set (kb): {PEAK_WORKING_SET} \
330 peak page file usage (kb): {PEAK_PAGE_FILE} \
331 peak paged pool usage (kb): {PEAK_PAGED_POOL} \
332 peak non-paged pool usage (kb): {PEAK_NONPAGED_POOL} \
333 page faults: {PAGE_FAULTS}",
334 USER_SEC = user_time.wSecond + (user_time.wMinute * 60),
335 USER_USEC = user_time.wMilliseconds,
336 SYS_SEC = kernel_time.wSecond + (kernel_time.wMinute * 60),
337 SYS_USEC = kernel_time.wMilliseconds,
338 PEAK_WORKING_SET = peak_working_set,
339 PEAK_PAGE_FILE = peak_page_file,
340 PEAK_PAGED_POOL = peak_paged_pool,
341 PEAK_NONPAGED_POOL = peak_nonpaged_pool,
342 PAGE_FAULTS = memory_counters.PageFaultCount,
347 /// Tries to build a string with human readable data for several of the rusage
348 /// fields. Note that we are focusing mainly on data that we believe to be
349 /// supplied on Linux (the `rusage` struct has other fields in it but they are
350 /// currently unsupported by Linux).
351 fn format_rusage_data(_child: Child) -> Option<String> {
352 let rusage: libc::rusage = unsafe {
353 let mut recv = std::mem::zeroed();
354 // -1 is RUSAGE_CHILDREN, which means to get the rusage for all children
355 // (and grandchildren, etc) processes that have respectively terminated
356 // and been waited for.
357 let retval = libc::getrusage(-1, &mut recv);
363 // Mac OS X reports the maxrss in bytes, not kb.
364 let divisor = if env::consts::OS == "macos" { 1024 } else { 1 };
365 let maxrss = (rusage.ru_maxrss + (divisor - 1)) / divisor;
367 let mut init_str = format!(
368 "user: {USER_SEC}.{USER_USEC:03} \
369 sys: {SYS_SEC}.{SYS_USEC:03} \
370 max rss (kb): {MAXRSS}",
371 USER_SEC = rusage.ru_utime.tv_sec,
372 USER_USEC = rusage.ru_utime.tv_usec,
373 SYS_SEC = rusage.ru_stime.tv_sec,
374 SYS_USEC = rusage.ru_stime.tv_usec,
378 // The remaining rusage stats vary in platform support. So we treat
379 // uniformly zero values in each category as "not worth printing", since it
380 // either means no events of that type occurred, or that the platform
381 // does not support it.
383 let minflt = rusage.ru_minflt;
384 let majflt = rusage.ru_majflt;
385 if minflt != 0 || majflt != 0 {
386 init_str.push_str(&format!(" page reclaims: {} page faults: {}", minflt, majflt));
389 let inblock = rusage.ru_inblock;
390 let oublock = rusage.ru_oublock;
391 if inblock != 0 || oublock != 0 {
392 init_str.push_str(&format!(" fs block inputs: {} fs block outputs: {}", inblock, oublock));
395 let nvcsw = rusage.ru_nvcsw;
396 let nivcsw = rusage.ru_nivcsw;
397 if nvcsw != 0 || nivcsw != 0 {
398 init_str.push_str(&format!(
399 " voluntary ctxt switches: {} involuntary ctxt switches: {}",
404 return Some(init_str);