1 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 //! Shim which is passed to Cargo as "rustc" when running the bootstrap.
13 //! This shim will take care of some various tasks that our build process
14 //! requires that Cargo can't quite do through normal configuration:
16 //! 1. When compiling build scripts and build dependencies, we need a guaranteed
17 //! full standard library available. The only compiler which actually has
18 //! this is the snapshot, so we detect this situation and always compile with
19 //! the snapshot compiler.
20 //! 2. We pass a bunch of `--cfg` and other flags based on what we're compiling
21 //! (and this slightly differs based on a whether we're using a snapshot or
22 //! not), so we do that all here.
24 //! This may one day be replaced by RUSTFLAGS, but the dynamic nature of
25 //! switching compilers for the bootstrap and for build scripts will probably
26 //! never get replaced.
28 extern crate bootstrap;
31 use std::ffi::OsString;
32 use std::path::PathBuf;
33 use std::process::Command;
36 let args = env::args_os().skip(1).collect::<Vec<_>>();
37 // Detect whether or not we're a build script depending on whether --target
38 // is passed (a bit janky...)
39 let target = args.windows(2).find(|w| &*w[0] == "--target")
40 .and_then(|w| w[1].to_str());
41 let version = args.iter().find(|w| &**w == "-vV");
43 // Build scripts always use the snapshot compiler which is guaranteed to be
44 // able to produce an executable, whereas intermediate compilers may not
45 // have the standard library built yet and may not be able to produce an
46 // executable. Otherwise we just use the standard compiler we're
47 // bootstrapping with.
49 // Also note that cargo will detect the version of the compiler to trigger
50 // a rebuild when the compiler changes. If this happens, we want to make
51 // sure to use the actual compiler instead of the snapshot compiler becase
52 // that's the one that's actually changing.
53 let (rustc, libdir) = if target.is_none() && version.is_none() {
54 ("RUSTC_SNAPSHOT", "RUSTC_SNAPSHOT_LIBDIR")
56 ("RUSTC_REAL", "RUSTC_LIBDIR")
58 let stage = env::var("RUSTC_STAGE").unwrap();
60 let rustc = env::var_os(rustc).unwrap();
61 let libdir = env::var_os(libdir).unwrap();
62 let mut dylib_path = bootstrap::util::dylib_path();
63 dylib_path.insert(0, PathBuf::from(libdir));
65 let mut cmd = Command::new(rustc);
67 .arg("--cfg").arg(format!("stage{}", stage))
68 .env(bootstrap::util::dylib_path_var(),
69 env::join_paths(&dylib_path).unwrap());
71 if let Some(target) = target {
72 // The stage0 compiler has a special sysroot distinct from what we
73 // actually downloaded, so we just always pass the `--sysroot` option.
74 cmd.arg("--sysroot").arg(env::var_os("RUSTC_SYSROOT").unwrap());
76 // When we build Rust dylibs they're all intended for intermediate
77 // usage, so make sure we pass the -Cprefer-dynamic flag instead of
78 // linking all deps statically into the dylib.
79 cmd.arg("-Cprefer-dynamic");
81 // Help the libc crate compile by assisting it in finding the MUSL
83 if let Some(s) = env::var_os("MUSL_ROOT") {
84 let mut root = OsString::from("native=");
87 cmd.arg("-L").arg(&root);
90 // Pass down extra flags, commonly used to configure `-Clinker` when
92 if let Ok(s) = env::var("RUSTC_FLAGS") {
93 cmd.args(&s.split(" ").filter(|s| !s.is_empty()).collect::<Vec<_>>());
96 // If we're compiling specifically the `panic_abort` crate then we pass
97 // the `-C panic=abort` option. Note that we do not do this for any
98 // other crate intentionally as this is the only crate for now that we
99 // ship with panic=abort.
101 // This... is a bit of a hack how we detect this. Ideally this
102 // information should be encoded in the crate I guess? Would likely
103 // require an RFC amendment to RFC 1513, however.
104 let is_panic_abort = args.windows(2).any(|a| {
105 &*a[0] == "--crate-name" && &*a[1] == "panic_abort"
107 // FIXME(stage0): remove this `stage != "0"` condition
108 if is_panic_abort && stage != "0" {
109 cmd.arg("-C").arg("panic=abort");
112 // Set various options from config.toml to configure how we're building
114 if env::var("RUSTC_DEBUGINFO") == Ok("true".to_string()) {
117 let debug_assertions = match env::var("RUSTC_DEBUG_ASSERTIONS") {
118 Ok(s) => if s == "true" {"y"} else {"n"},
121 cmd.arg("-C").arg(format!("debug-assertions={}", debug_assertions));
122 if let Ok(s) = env::var("RUSTC_CODEGEN_UNITS") {
123 cmd.arg("-C").arg(format!("codegen-units={}", s));
126 // Dealing with rpath here is a little special, so let's go into some
127 // detail. First off, `-rpath` is a linker option on Unix platforms
128 // which adds to the runtime dynamic loader path when looking for
129 // dynamic libraries. We use this by default on Unix platforms to ensure
130 // that our nightlies behave the same on Windows, that is they work out
131 // of the box. This can be disabled, of course, but basically that's why
132 // we're gated on RUSTC_RPATH here.
134 // Ok, so the astute might be wondering "why isn't `-C rpath` used
135 // here?" and that is indeed a good question to task. This codegen
136 // option is the compiler's current interface to generating an rpath.
137 // Unfortunately it doesn't quite suffice for us. The flag currently
138 // takes no value as an argument, so the compiler calculates what it
139 // should pass to the linker as `-rpath`. This unfortunately is based on
140 // the **compile time** directory structure which when building with
141 // Cargo will be very different than the runtime directory structure.
143 // All that's a really long winded way of saying that if we use
144 // `-Crpath` then the executables generated have the wrong rpath of
145 // something like `$ORIGIN/deps` when in fact the way we distribute
146 // rustc requires the rpath to be `$ORIGIN/../lib`.
148 // So, all in all, to set up the correct rpath we pass the linker
149 // argument manually via `-C link-args=-Wl,-rpath,...`. Plus isn't it
150 // fun to pass a flag to a tool to pass a flag to pass a flag to a tool
151 // to change a flag in a binary?
152 if env::var("RUSTC_RPATH") == Ok("true".to_string()) {
153 let rpath = if target.contains("apple") {
154 Some("-Wl,-rpath,@loader_path/../lib")
155 } else if !target.contains("windows") {
156 Some("-Wl,-rpath,$ORIGIN/../lib")
160 if let Some(rpath) = rpath {
161 cmd.arg("-C").arg(format!("link-args={}", rpath));
166 // Actually run the compiler!
167 std::process::exit(match cmd.status() {
168 Ok(s) => s.code().unwrap_or(1),
169 Err(e) => panic!("\n\nfailed to run {:?}: {}\n\n", cmd, e),