Import subrepo gcc/:gcc at cf1f00bc038a0df769e14bb85480ab9c12eae08d

4 files changed, 1790 insertions, 0 deletions

diff --git a/gcc/src/bin/gcc-shim.rs b/gcc/src/bin/gcc-shim.rs
new file mode 100644
index 0000000..7fd0ea8
--- /dev/null
+++ b/gcc/src/bin/gcc-shim.rs
@@ -0,0 +1,23 @@
+#![cfg_attr(test, allow(dead_code))]
+
+use std::env;
+use std::fs::File;
+use std::io::prelude::*;
+use std::path::PathBuf;
+
+fn main() {
+    let out_dir = PathBuf::from(env::var_os("GCCTEST_OUT_DIR").unwrap());
+    for i in 0.. {
+        let candidate = out_dir.join(format!("out{}", i));
+        if candidate.exists() {
+            continue;
+        }
+        let mut f = File::create(candidate).unwrap();
+        for arg in env::args().skip(1) {
+            writeln!(f, "{}", arg).unwrap();
+        }
+
+        File::create(out_dir.join("libfoo.a")).unwrap();
+        break;
+    }
+}
diff --git a/gcc/src/lib.rs b/gcc/src/lib.rs
new file mode 100644
index 0000000..85d7d22
--- /dev/null
+++ b/gcc/src/lib.rs
@@ -0,0 +1,1153 @@
+//! A library for build scripts to compile custom C code
+//!
+//! This library is intended to be used as a `build-dependencies` entry in
+//! `Cargo.toml`:
+//!
+//! ```toml
+//! [build-dependencies]
+//! gcc = "0.3"
+//! ```
+//!
+//! The purpose of this crate is to provide the utility functions necessary to
+//! compile C code into a static archive which is then linked into a Rust crate.
+//! The top-level `compile_library` function serves as a convenience and more
+//! advanced configuration is available through the `Config` builder.
+//!
+//! This crate will automatically detect situations such as cross compilation or
+//! other environment variables set by Cargo and will build code appropriately.
+//!
+//! # Examples
+//!
+//! Use the default configuration:
+//!
+//! ```no_run
+//! extern crate gcc;
+//!
+//! fn main() {
+//!     gcc::compile_library("libfoo.a", &["src/foo.c"]);
+//! }
+//! ```
+//!
+//! Use more advanced configuration:
+//!
+//! ```no_run
+//! extern crate gcc;
+//!
+//! fn main() {
+//!     gcc::Config::new()
+//!                 .file("src/foo.c")
+//!                 .define("FOO", Some("bar"))
+//!                 .include("src")
+//!                 .compile("libfoo.a");
+//! }
+//! ```
+
+#![doc(html_root_url = "https://docs.rs/gcc/0.3")]
+#![cfg_attr(test, deny(warnings))]
+#![deny(missing_docs)]
+
+#[cfg(feature = "parallel")]
+extern crate rayon;
+
+use std::env;
+use std::ffi::{OsString, OsStr};
+use std::fs;
+use std::path::{PathBuf, Path};
+use std::process::{Command, Stdio, Child};
+use std::io::{self, BufReader, BufRead, Read, Write};
+use std::thread::{self, JoinHandle};
+
+#[cfg(windows)]
+mod registry;
+pub mod windows_registry;
+
+/// Extra configuration to pass to gcc.
+pub struct Config {
+    include_directories: Vec<PathBuf>,
+    definitions: Vec<(String, Option<String>)>,
+    objects: Vec<PathBuf>,
+    flags: Vec<String>,
+    files: Vec<PathBuf>,
+    cpp: bool,
+    cpp_link_stdlib: Option<Option<String>>,
+    cpp_set_stdlib: Option<String>,
+    target: Option<String>,
+    host: Option<String>,
+    out_dir: Option<PathBuf>,
+    opt_level: Option<String>,
+    debug: Option<bool>,
+    env: Vec<(OsString, OsString)>,
+    compiler: Option<PathBuf>,
+    archiver: Option<PathBuf>,
+    cargo_metadata: bool,
+    pic: Option<bool>,
+}
+
+/// Configuration used to represent an invocation of a C compiler.
+///
+/// This can be used to figure out what compiler is in use, what the arguments
+/// to it are, and what the environment variables look like for the compiler.
+/// This can be used to further configure other build systems (e.g. forward
+/// along CC and/or CFLAGS) or the `to_command` method can be used to run the
+/// compiler itself.
+pub struct Tool {
+    path: PathBuf,
+    args: Vec<OsString>,
+    env: Vec<(OsString, OsString)>,
+    family: ToolFamily
+}
+
+/// Represents the family of tools this tool belongs to.
+///
+/// Each family of tools differs in how and what arguments they accept.
+///
+/// Detection of a family is done on best-effort basis and may not accurately reflect the tool.
+#[derive(Copy, Clone, Debug)]
+enum ToolFamily {
+    /// Tool is GNU Compiler Collection-like.
+    Gnu,
+    /// Tool is Clang-like. It differs from the GCC in a sense that it accepts superset of flags
+    /// and its cross-compilation approach is different.
+    Clang,
+    /// Tool is the MSVC cl.exe.
+    Msvc,
+}
+
+impl ToolFamily {
+    /// What the flag to request debug info for this family of tools look like
+    fn debug_flag(&self) -> &'static str {
+        match *self {
+            ToolFamily::Msvc => "/Z7",
+            ToolFamily::Gnu |
+            ToolFamily::Clang => "-g",
+        }
+    }
+
+    /// What the flag to include directories into header search path looks like
+    fn include_flag(&self) -> &'static str {
+        match *self {
+            ToolFamily::Msvc => "/I",
+            ToolFamily::Gnu |
+            ToolFamily::Clang => "-I",
+        }
+    }
+
+    /// What the flag to request macro-expanded source output looks like
+    fn expand_flag(&self) -> &'static str {
+        match *self {
+            ToolFamily::Msvc => "/E",
+            ToolFamily::Gnu |
+            ToolFamily::Clang => "-E",
+        }
+    }
+}
+
+/// Compile a library from the given set of input C files.
+///
+/// This will simply compile all files into object files and then assemble them
+/// into the output. This will read the standard environment variables to detect
+/// cross compilations and such.
+///
+/// This function will also print all metadata on standard output for Cargo.
+///
+/// # Example
+///
+/// ```no_run
+/// gcc::compile_library("libfoo.a", &["foo.c", "bar.c"]);
+/// ```
+pub fn compile_library(output: &str, files: &[&str]) {
+    let mut c = Config::new();
+    for f in files.iter() {
+        c.file(*f);
+    }
+    c.compile(output);
+}
+
+impl Config {
+    /// Construct a new instance of a blank set of configuration.
+    ///
+    /// This builder is finished with the `compile` function.
+    pub fn new() -> Config {
+        Config {
+            include_directories: Vec::new(),
+            definitions: Vec::new(),
+            objects: Vec::new(),
+            flags: Vec::new(),
+            files: Vec::new(),
+            cpp: false,
+            cpp_link_stdlib: None,
+            cpp_set_stdlib: None,
+            target: None,
+            host: None,
+            out_dir: None,
+            opt_level: None,
+            debug: None,
+            env: Vec::new(),
+            compiler: None,
+            archiver: None,
+            cargo_metadata: true,
+            pic: None,
+        }
+    }
+
+    /// Add a directory to the `-I` or include path for headers
+    pub fn include<P: AsRef<Path>>(&mut self, dir: P) -> &mut Config {
+        self.include_directories.push(dir.as_ref().to_path_buf());
+        self
+    }
+
+    /// Specify a `-D` variable with an optional value.
+    pub fn define(&mut self, var: &str, val: Option<&str>) -> &mut Config {
+        self.definitions.push((var.to_string(), val.map(|s| s.to_string())));
+        self
+    }
+
+    /// Add an arbitrary object file to link in
+    pub fn object<P: AsRef<Path>>(&mut self, obj: P) -> &mut Config {
+        self.objects.push(obj.as_ref().to_path_buf());
+        self
+    }
+
+    /// Add an arbitrary flag to the invocation of the compiler
+    pub fn flag(&mut self, flag: &str) -> &mut Config {
+        self.flags.push(flag.to_string());
+        self
+    }
+
+    /// Add a file which will be compiled
+    pub fn file<P: AsRef<Path>>(&mut self, p: P) -> &mut Config {
+        self.files.push(p.as_ref().to_path_buf());
+        self
+    }
+
+    /// Set C++ support.
+    ///
+    /// The other `cpp_*` options will only become active if this is set to
+    /// `true`.
+    pub fn cpp(&mut self, cpp: bool) -> &mut Config {
+        self.cpp = cpp;
+        self
+    }
+
+    /// Set the standard library to link against when compiling with C++
+    /// support.
+    ///
+    /// The default value of this property depends on the current target: On
+    /// OS X `Some("c++")` is used, when compiling for a Visual Studio based
+    /// target `None` is used and for other targets `Some("stdc++")` is used.
+    ///
+    /// A value of `None` indicates that no automatic linking should happen,
+    /// otherwise cargo will link against the specified library.
+    ///
+    /// The given library name must not contain the `lib` prefix.
+    pub fn cpp_link_stdlib(&mut self, cpp_link_stdlib: Option<&str>) -> &mut Config {
+        self.cpp_link_stdlib = Some(cpp_link_stdlib.map(|s| s.into()));
+        self
+    }
+
+    /// Force the C++ compiler to use the specified standard library.
+    ///
+    /// Setting this option will automatically set `cpp_link_stdlib` to the same
+    /// value.
+    ///
+    /// The default value of this option is always `None`.
+    ///
+    /// This option has no effect when compiling for a Visual Studio based
+    /// target.
+    ///
+    /// This option sets the `-stdlib` flag, which is only supported by some
+    /// compilers (clang, icc) but not by others (gcc). The library will not
+    /// detect which compiler is used, as such it is the responsibility of the
+    /// caller to ensure that this option is only used in conjuction with a
+    /// compiler which supports the `-stdlib` flag.
+    ///
+    /// A value of `None` indicates that no specific C++ standard library should
+    /// be used, otherwise `-stdlib` is added to the compile invocation.
+    ///
+    /// The given library name must not contain the `lib` prefix.
+    pub fn cpp_set_stdlib(&mut self, cpp_set_stdlib: Option<&str>) -> &mut Config {
+        self.cpp_set_stdlib = cpp_set_stdlib.map(|s| s.into());
+        self.cpp_link_stdlib(cpp_set_stdlib);
+        self
+    }
+
+    /// Configures the target this configuration will be compiling for.
+    ///
+    /// This option is automatically scraped from the `TARGET` environment
+    /// variable by build scripts, so it's not required to call this function.
+    pub fn target(&mut self, target: &str) -> &mut Config {
+        self.target = Some(target.to_string());
+        self
+    }
+
+    /// Configures the host assumed by this configuration.
+    ///
+    /// This option is automatically scraped from the `HOST` environment
+    /// variable by build scripts, so it's not required to call this function.
+    pub fn host(&mut self, host: &str) -> &mut Config {
+        self.host = Some(host.to_string());
+        self
+    }
+
+    /// Configures the optimization level of the generated object files.
+    ///
+    /// This option is automatically scraped from the `OPT_LEVEL` environment
+    /// variable by build scripts, so it's not required to call this function.
+    pub fn opt_level(&mut self, opt_level: u32) -> &mut Config {
+        self.opt_level = Some(opt_level.to_string());
+        self
+    }
+
+    /// Configures the optimization level of the generated object files.
+    ///
+    /// This option is automatically scraped from the `OPT_LEVEL` environment
+    /// variable by build scripts, so it's not required to call this function.
+    pub fn opt_level_str(&mut self, opt_level: &str) -> &mut Config {
+        self.opt_level = Some(opt_level.to_string());
+        self
+    }
+
+    /// Configures whether the compiler will emit debug information when
+    /// generating object files.
+    ///
+    /// This option is automatically scraped from the `PROFILE` environment
+    /// variable by build scripts (only enabled when the profile is "debug"), so
+    /// it's not required to call this function.
+    pub fn debug(&mut self, debug: bool) -> &mut Config {
+        self.debug = Some(debug);
+        self
+    }
+
+    /// Configures the output directory where all object files and static
+    /// libraries will be located.
+    ///
+    /// This option is automatically scraped from the `OUT_DIR` environment
+    /// variable by build scripts, so it's not required to call this function.
+    pub fn out_dir<P: AsRef<Path>>(&mut self, out_dir: P) -> &mut Config {
+        self.out_dir = Some(out_dir.as_ref().to_owned());
+        self
+    }
+
+    /// Configures the compiler to be used to produce output.
+    ///
+    /// This option is automatically determined from the target platform or a
+    /// number of environment variables, so it's not required to call this
+    /// function.
+    pub fn compiler<P: AsRef<Path>>(&mut self, compiler: P) -> &mut Config {
+        self.compiler = Some(compiler.as_ref().to_owned());
+        self
+    }
+
+    /// Configures the tool used to assemble archives.
+    ///
+    /// This option is automatically determined from the target platform or a
+    /// number of environment variables, so it's not required to call this
+    /// function.
+    pub fn archiver<P: AsRef<Path>>(&mut self, archiver: P) -> &mut Config {
+        self.archiver = Some(archiver.as_ref().to_owned());
+        self
+    }
+    /// Define whether metadata should be emitted for cargo allowing it to
+    /// automatically link the binary. Defaults to `true`.
+    pub fn cargo_metadata(&mut self, cargo_metadata: bool) -> &mut Config {
+        self.cargo_metadata = cargo_metadata;
+        self
+    }
+
+    /// Configures whether the compiler will emit position independent code.
+    ///
+    /// This option defaults to `false` for `windows-gnu` targets and
+    /// to `true` for all other targets.
+    pub fn pic(&mut self, pic: bool) -> &mut Config {
+        self.pic = Some(pic);
+        self
+    }
+
+
+    #[doc(hidden)]
+    pub fn __set_env<A, B>(&mut self, a: A, b: B) -> &mut Config
+        where A: AsRef<OsStr>,
+              B: AsRef<OsStr>
+    {
+        self.env.push((a.as_ref().to_owned(), b.as_ref().to_owned()));
+        self
+    }
+
+    /// Run the compiler, generating the file `output`
+    ///
+    /// The name `output` must begin with `lib` and end with `.a`
+    pub fn compile(&self, output: &str) {
+        assert!(output.starts_with("lib"));
+        assert!(output.ends_with(".a"));
+        let lib_name = &output[3..output.len() - 2];
+        let dst = self.get_out_dir();
+
+        let mut objects = Vec::new();
+        let mut src_dst = Vec::new();
+        for file in self.files.iter() {
+            let obj = dst.join(file).with_extension("o");
+            let obj = if !obj.starts_with(&dst) {
+                dst.join(obj.file_name().unwrap())
+            } else {
+                obj
+            };
+            fs::create_dir_all(&obj.parent().unwrap()).unwrap();
+            src_dst.push((file.to_path_buf(), obj.clone()));
+            objects.push(obj);
+        }
+        self.compile_objects(&src_dst);
+        self.assemble(lib_name, &dst.join(output), &objects);
+
+        if self.get_target().contains("msvc") {
+            let compiler = self.get_base_compiler();
+            let atlmfc_lib = compiler.env()
+                .iter()
+                .find(|&&(ref var, _)| var.as_os_str() == OsStr::new("LIB"))
+                .and_then(|&(_, ref lib_paths)| {
+                    env::split_paths(lib_paths).find(|path| {
+                        let sub = Path::new("atlmfc/lib");
+                        path.ends_with(sub) || path.parent().map_or(false, |p| p.ends_with(sub))
+                    })
+                });
+
+            if let Some(atlmfc_lib) = atlmfc_lib {
+                self.print(&format!("cargo:rustc-link-search=native={}", atlmfc_lib.display()));
+            }
+        }
+
+        self.print(&format!("cargo:rustc-link-lib=static={}",
+                            &output[3..output.len() - 2]));
+        self.print(&format!("cargo:rustc-link-search=native={}", dst.display()));
+
+        // Add specific C++ libraries, if enabled.
+        if self.cpp {
+            if let Some(stdlib) = self.get_cpp_link_stdlib() {
+                self.print(&format!("cargo:rustc-link-lib={}", stdlib));
+            }
+        }
+    }
+
+    #[cfg(feature = "parallel")]
+    fn compile_objects(&self, objs: &[(PathBuf, PathBuf)]) {
+        use self::rayon::prelude::*;
+
+        let mut cfg = rayon::Configuration::new();
+        if let Ok(amt) = env::var("NUM_JOBS") {
+            if let Ok(amt) = amt.parse() {
+                cfg = cfg.set_num_threads(amt);
+            }
+        }
+        drop(rayon::initialize(cfg));
+
+        objs.par_iter().weight_max().for_each(|&(ref src, ref dst)| self.compile_object(src, dst));
+    }
+
+    #[cfg(not(feature = "parallel"))]
+    fn compile_objects(&self, objs: &[(PathBuf, PathBuf)]) {
+        for &(ref src, ref dst) in objs {
+            self.compile_object(src, dst);
+        }
+    }
+
+    fn compile_object(&self, file: &Path, dst: &Path) {
+        let is_asm = file.extension().and_then(|s| s.to_str()) == Some("asm");
+        let msvc = self.get_target().contains("msvc");
+        let (mut cmd, name) = if msvc && is_asm {
+            self.msvc_macro_assembler()
+        } else {
+            let compiler = self.get_compiler();
+            let mut cmd = compiler.to_command();
+            for &(ref a, ref b) in self.env.iter() {
+                cmd.env(a, b);
+            }
+            (cmd,
+             compiler.path
+                 .file_name()
+                 .unwrap()
+                 .to_string_lossy()
+                 .into_owned())
+        };
+        if msvc && is_asm {
+            cmd.arg("/Fo").arg(dst);
+        } else if msvc {
+            let mut s = OsString::from("/Fo");
+            s.push(&dst);
+            cmd.arg(s);
+        } else {
+            cmd.arg("-o").arg(&dst);
+        }
+        cmd.arg(if msvc { "/c" } else { "-c" });
+        cmd.arg(file);
+
+        run(&mut cmd, &name);
+    }
+
+    /// Run the compiler, returning the macro-expanded version of the input files.
+    ///
+    /// This is only relevant for C and C++ files.
+    pub fn expand(&self) -> Vec<u8> {
+        let compiler = self.get_compiler();
+        let mut cmd = compiler.to_command();
+        for &(ref a, ref b) in self.env.iter() {
+            cmd.env(a, b);
+        }
+        cmd.arg(compiler.family.expand_flag());
+        for file in self.files.iter() {
+            cmd.arg(file);
+        }
+
+        let name = compiler.path
+            .file_name()
+            .unwrap()
+            .to_string_lossy()
+            .into_owned();
+
+        run_output(&mut cmd, &name)
+    }
+
+    /// Get the compiler that's in use for this configuration.
+    ///
+    /// This function will return a `Tool` which represents the culmination
+    /// of this configuration at a snapshot in time. The returned compiler can
+    /// be inspected (e.g. the path, arguments, environment) to forward along to
+    /// other tools, or the `to_command` method can be used to invoke the
+    /// compiler itself.
+    ///
+    /// This method will take into account all configuration such as debug
+    /// information, optimization level, include directories, defines, etc.
+    /// Additionally, the compiler binary in use follows the standard
+    /// conventions for this path, e.g. looking at the explicitly set compiler,
+    /// environment variables (a number of which are inspected here), and then
+    /// falling back to the default configuration.
+    pub fn get_compiler(&self) -> Tool {
+        let opt_level = self.get_opt_level();
+        let target = self.get_target();
+
+        let mut cmd = self.get_base_compiler();
+        let nvcc = cmd.path.file_name()
+            .and_then(|p| p.to_str()).map(|p| p.contains("nvcc"))
+            .unwrap_or(false);
+
+        // Non-target flags
+        // If the flag is not conditioned on target variable, it belongs here :)
+        match cmd.family {
+            ToolFamily::Msvc => {
+                cmd.args.push("/nologo".into());
+                let features = env::var("CARGO_CFG_TARGET_FEATURE")
+                                  .unwrap_or(String::new());
+                if features.contains("crt-static") {
+                    cmd.args.push("/MT".into());
+                } else {
+                    cmd.args.push("/MD".into());
+                }
+                match &opt_level[..] {
+                    "z" | "s" => cmd.args.push("/Os".into()),
+                    "1" => cmd.args.push("/O1".into()),
+                    // -O3 is a valid value for gcc and clang compilers, but not msvc. Cap to /O2.
+                    "2" | "3" => cmd.args.push("/O2".into()),
+                    _ => {}
+                }
+            }
+            ToolFamily::Gnu |
+            ToolFamily::Clang => {
+                cmd.args.push(format!("-O{}", opt_level).into());
+                if !nvcc {
+                    cmd.args.push("-ffunction-sections".into());
+                    cmd.args.push("-fdata-sections".into());
+                    if self.pic.unwrap_or(!target.contains("windows-gnu")) {
+                        cmd.args.push("-fPIC".into());
+                    }
+                } else if self.pic.unwrap_or(false) {
+                    cmd.args.push("-Xcompiler".into());
+                    cmd.args.push("\'-fPIC\'".into());
+                }
+            }
+        }
+        for arg in self.envflags(if self.cpp {"CXXFLAGS"} else {"CFLAGS"}) {
+            cmd.args.push(arg.into());
+        }
+
+        if self.get_debug() {
+            cmd.args.push(cmd.family.debug_flag().into());
+        }
+
+        // Target flags
+        match cmd.family {
+            ToolFamily::Clang => {
+                cmd.args.push(format!("--target={}", target).into());
+            }
+            ToolFamily::Msvc => {
+                if target.contains("i586") {
+                    cmd.args.push("/ARCH:IA32".into());
+                }
+            }
+            ToolFamily::Gnu => {
+                if target.contains("i686") || target.contains("i586") {
+                    cmd.args.push("-m32".into());
+                } else if target.contains("x86_64") || target.contains("powerpc64") {
+                    cmd.args.push("-m64".into());
+                }
+
+                if target.contains("musl") {
+                    cmd.args.push("-static".into());
+                }
+
+                // armv7 targets get to use armv7 instructions
+                if target.starts_with("armv7-unknown-linux-") {
+                    cmd.args.push("-march=armv7-a".into());
+                }
+
+                // On android we can guarantee some extra float instructions
+                // (specified in the android spec online)
+                if target.starts_with("armv7-linux-androideabi") {
+                    cmd.args.push("-march=armv7-a".into());
+                    cmd.args.push("-mfpu=vfpv3-d16".into());
+                }
+
+                // For us arm == armv6 by default
+                if target.starts_with("arm-unknown-linux-") {
+                    cmd.args.push("-march=armv6".into());
+                    cmd.args.push("-marm".into());
+                }
+
+                // Turn codegen down on i586 to avoid some instructions.
+                if target.starts_with("i586-unknown-linux-") {
+                    cmd.args.push("-march=pentium".into());
+                }
+
+                // Set codegen level for i686 correctly
+                if target.starts_with("i686-unknown-linux-") {
+                    cmd.args.push("-march=i686".into());
+                }
+
+                // Looks like `musl-gcc` makes is hard for `-m32` to make its way
+                // all the way to the linker, so we need to actually instruct the
+                // linker that we're generating 32-bit executables as well. This'll
+                // typically only be used for build scripts which transitively use
+                // these flags that try to compile executables.
+                if target == "i686-unknown-linux-musl" {
+                    cmd.args.push("-Wl,-melf_i386".into());
+                }
+
+                if target.starts_with("thumb") {
+                    cmd.args.push("-mthumb".into());
+
+                    if target.ends_with("eabihf") {
+                        cmd.args.push("-mfloat-abi=hard".into())
+                    }
+                }
+                if target.starts_with("thumbv6m") {
+                    cmd.args.push("-march=armv6s-m".into());
+                }
+                if target.starts_with("thumbv7em") {
+                    cmd.args.push("-march=armv7e-m".into());
+
+                    if target.ends_with("eabihf") {
+                        cmd.args.push("-mfpu=fpv4-sp-d16".into())
+                    }
+                }
+                if target.starts_with("thumbv7m") {
+                    cmd.args.push("-march=armv7-m".into());
+                }
+            }
+        }
+
+        if target.contains("-ios") {
+            // FIXME: potential bug. iOS is always compiled with Clang, but Gcc compiler may be
+            // detected instead.
+            self.ios_flags(&mut cmd);
+        }
+
+        if self.cpp {
+            match (self.cpp_set_stdlib.as_ref(), cmd.family) {
+                (None, _) => { }
+                (Some(stdlib), ToolFamily::Gnu) |
+                (Some(stdlib), ToolFamily::Clang) => {
+                    cmd.args.push(format!("-stdlib=lib{}", stdlib).into());
+                }
+                _ => {
+                    println!("cargo:warning=cpp_set_stdlib is specified, but the {:?} compiler \
+                              does not support this option, ignored", cmd.family);
+                }
+            }
+        }
+
+        for directory in self.include_directories.iter() {
+            cmd.args.push(cmd.family.include_flag().into());
+            cmd.args.push(directory.into());
+        }
+
+        for flag in self.flags.iter() {
+            cmd.args.push(flag.into());
+        }
+
+        for &(ref key, ref value) in self.definitions.iter() {
+            let lead = if let ToolFamily::Msvc = cmd.family {"/"} else {"-"};
+            if let &Some(ref value) = value {
+                cmd.args.push(format!("{}D{}={}", lead, key, value).into());
+            } else {
+                cmd.args.push(format!("{}D{}", lead, key).into());
+            }
+        }
+        cmd
+    }
+
+    fn msvc_macro_assembler(&self) -> (Command, String) {
+        let target = self.get_target();
+        let tool = if target.contains("x86_64") {
+            "ml64.exe"
+        } else {
+            "ml.exe"
+        };
+        let mut cmd = windows_registry::find(&target, tool).unwrap_or_else(|| self.cmd(tool));
+        for directory in self.include_directories.iter() {
+            cmd.arg("/I").arg(directory);
+        }
+        for &(ref key, ref value) in self.definitions.iter() {
+            if let &Some(ref value) = value {
+                cmd.arg(&format!("/D{}={}", key, value));
+            } else {
+                cmd.arg(&format!("/D{}", key));
+            }
+        }
+
+        if target.contains("i686") || target.contains("i586") {
+            cmd.arg("/safeseh");
+        }
+        for flag in self.flags.iter() {
+            cmd.arg(flag);
+        }
+
+        (cmd, tool.to_string())
+    }
+
+    fn assemble(&self, lib_name: &str, dst: &Path, objects: &[PathBuf]) {
+        // Delete the destination if it exists as the `ar` tool at least on Unix
+        // appends to it, which we don't want.
+        let _ = fs::remove_file(&dst);
+
+        let target = self.get_target();
+        if target.contains("msvc") {
+            let mut cmd = match self.archiver {
+                Some(ref s) => self.cmd(s),
+                None => windows_registry::find(&target, "lib.exe").unwrap_or(self.cmd("lib.exe")),
+            };
+            let mut out = OsString::from("/OUT:");
+            out.push(dst);
+            run(cmd.arg(out)
+                    .arg("/nologo")
+                    .args(objects)
+                    .args(&self.objects),
+                "lib.exe");
+
+            // The Rust compiler will look for libfoo.a and foo.lib, but the
+            // MSVC linker will also be passed foo.lib, so be sure that both
+            // exist for now.
+            let lib_dst = dst.with_file_name(format!("{}.lib", lib_name));
+            let _ = fs::remove_file(&lib_dst);
+            fs::hard_link(&dst, &lib_dst)
+                .or_else(|_| {
+                    // if hard-link fails, just copy (ignoring the number of bytes written)
+                    fs::copy(&dst, &lib_dst).map(|_| ())
+                })
+                .ok()
+                .expect("Copying from {:?} to {:?} failed.");;
+        } else {
+            let ar = self.get_ar();
+            let cmd = ar.file_name().unwrap().to_string_lossy();
+            run(self.cmd(&ar)
+                    .arg("crs")
+                    .arg(dst)
+                    .args(objects)
+                    .args(&self.objects),
+                &cmd);
+        }
+    }
+
+    fn ios_flags(&self, cmd: &mut Tool) {
+        enum ArchSpec {
+            Device(&'static str),
+            Simulator(&'static str),
+        }
+
+        let target = self.get_target();
+        let arch = target.split('-').nth(0).unwrap();
+        let arch = match arch {
+            "arm" | "armv7" | "thumbv7" => ArchSpec::Device("armv7"),
+            "armv7s" | "thumbv7s" => ArchSpec::Device("armv7s"),
+            "arm64" | "aarch64" => ArchSpec::Device("arm64"),
+            "i386" | "i686" => ArchSpec::Simulator("-m32"),
+            "x86_64" => ArchSpec::Simulator("-m64"),
+            _ => fail("Unknown arch for iOS target"),
+        };
+
+        let sdk = match arch {
+            ArchSpec::Device(arch) => {
+                cmd.args.push("-arch".into());
+                cmd.args.push(arch.into());
+                cmd.args.push("-miphoneos-version-min=7.0".into());
+                "iphoneos"
+            }
+            ArchSpec::Simulator(arch) => {
+                cmd.args.push(arch.into());
+                cmd.args.push("-mios-simulator-version-min=7.0".into());
+                "iphonesimulator"
+            }
+        };
+
+        self.print(&format!("Detecting iOS SDK path for {}", sdk));
+        let sdk_path = self.cmd("xcrun")
+            .arg("--show-sdk-path")
+            .arg("--sdk")
+            .arg(sdk)
+            .stderr(Stdio::inherit())
+            .output()
+            .unwrap()
+            .stdout;
+
+        let sdk_path = String::from_utf8(sdk_path).unwrap();
+
+        cmd.args.push("-isysroot".into());
+        cmd.args.push(sdk_path.trim().into());
+    }
+
+    fn cmd<P: AsRef<OsStr>>(&self, prog: P) -> Command {
+        let mut cmd = Command::new(prog);
+        for &(ref a, ref b) in self.env.iter() {
+            cmd.env(a, b);
+        }
+        return cmd;
+    }
+
+    fn get_base_compiler(&self) -> Tool {
+        if let Some(ref c) = self.compiler {
+            return Tool::new(c.clone());
+        }
+        let host = self.get_host();
+        let target = self.get_target();
+        let (env, msvc, gnu) = if self.cpp {
+            ("CXX", "cl.exe", "g++")
+        } else {
+            ("CC", "cl.exe", "gcc")
+        };
+
+        let default = if host.contains("solaris") {
+            // In this case, c++/cc unlikely to exist or be correct.
+            gnu
+        } else if self.cpp {
+            "c++"
+        } else {
+            "cc"
+        };
+
+        self.env_tool(env)
+            .map(|(tool, args)| {
+                let mut t = Tool::new(PathBuf::from(tool));
+                for arg in args {
+                    t.args.push(arg.into());
+                }
+                return t;
+            })
+            .or_else(|| {
+                if target.contains("emscripten") {
+                    if self.cpp {
+                        Some(Tool::new(PathBuf::from("em++")))
+                    } else {
+                        Some(Tool::new(PathBuf::from("emcc")))
+                    }
+                } else {
+                    None
+                }
+            })
+            .or_else(|| windows_registry::find_tool(&target, "cl.exe"))
+            .unwrap_or_else(|| {
+                let compiler = if host.contains("windows") && target.contains("windows") {
+                    if target.contains("msvc") {
+                        msvc.to_string()
+                    } else {
+                        format!("{}.exe", gnu)
+                    }
+                } else if target.contains("android") {
+                    format!("{}-{}", target.replace("armv7", "arm"), gnu)
+                } else if self.get_host() != target {
+                    // CROSS_COMPILE is of the form: "arm-linux-gnueabi-"
+                    let cc_env = self.getenv("CROSS_COMPILE");
+                    let cross_compile = cc_env.as_ref().map(|s| s.trim_right_matches('-'));
+                    let prefix = cross_compile.or(match &target[..] {
+                        "aarch64-unknown-linux-gnu" => Some("aarch64-linux-gnu"),
+                        "arm-unknown-linux-gnueabi" => Some("arm-linux-gnueabi"),
+                        "arm-unknown-linux-gnueabihf" => Some("arm-linux-gnueabihf"),
+                        "arm-unknown-linux-musleabi" => Some("arm-linux-musleabi"),
+                        "arm-unknown-linux-musleabihf" => Some("arm-linux-musleabihf"),
+                        "arm-unknown-netbsdelf-eabi" => Some("arm--netbsdelf-eabi"),
+                        "armv6-unknown-netbsdelf-eabihf" => Some("armv6--netbsdelf-eabihf"),
+                        "armv7-unknown-linux-gnueabihf" => Some("arm-linux-gnueabihf"),
+                        "armv7-unknown-linux-musleabihf" => Some("arm-linux-musleabihf"),
+                        "armv7-unknown-netbsdelf-eabihf" => Some("armv7--netbsdelf-eabihf"),
+                        "i686-pc-windows-gnu" => Some("i686-w64-mingw32"),
+                        "i686-unknown-linux-musl" => Some("musl"),
+                        "i686-unknown-netbsdelf" => Some("i486--netbsdelf"),
+                        "mips-unknown-linux-gnu" => Some("mips-linux-gnu"),
+                        "mipsel-unknown-linux-gnu" => Some("mipsel-linux-gnu"),
+                        "mips64-unknown-linux-gnuabi64" => Some("mips64-linux-gnuabi64"),
+                        "mips64el-unknown-linux-gnuabi64" => Some("mips64el-linux-gnuabi64"),
+                        "powerpc-unknown-linux-gnu" => Some("powerpc-linux-gnu"),
+                        "powerpc-unknown-netbsd" => Some("powerpc--netbsd"),
+                        "powerpc64-unknown-linux-gnu" => Some("powerpc-linux-gnu"),
+                        "powerpc64le-unknown-linux-gnu" => Some("powerpc64le-linux-gnu"),
+                        "s390x-unknown-linux-gnu" => Some("s390x-linux-gnu"),
+                        "sparc64-unknown-netbsd" => Some("sparc64--netbsd"),
+                        "sparcv9-sun-solaris" => Some("sparcv9-sun-solaris"),
+                        "thumbv6m-none-eabi" => Some("arm-none-eabi"),
+                        "thumbv7em-none-eabi" => Some("arm-none-eabi"),
+                        "thumbv7em-none-eabihf" => Some("arm-none-eabi"),
+                        "thumbv7m-none-eabi" => Some("arm-none-eabi"),
+                        "x86_64-pc-windows-gnu" => Some("x86_64-w64-mingw32"),
+                        "x86_64-rumprun-netbsd" => Some("x86_64-rumprun-netbsd"),
+                        "x86_64-unknown-linux-musl" => Some("musl"),
+                        "x86_64-unknown-netbsd" => Some("x86_64--netbsd"),
+                        _ => None,
+                    });
+                    match prefix {
+                        Some(prefix) => format!("{}-{}", prefix, gnu),
+                        None => default.to_string(),
+                    }
+                } else {
+                    default.to_string()
+                };
+                Tool::new(PathBuf::from(compiler))
+            })
+    }
+
+    fn get_var(&self, var_base: &str) -> Result<String, String> {
+        let target = self.get_target();
+        let host = self.get_host();
+        let kind = if host == target { "HOST" } else { "TARGET" };
+        let target_u = target.replace("-", "_");
+        let res = self.getenv(&format!("{}_{}", var_base, target))
+            .or_else(|| self.getenv(&format!("{}_{}", var_base, target_u)))
+            .or_else(|| self.getenv(&format!("{}_{}", kind, var_base)))
+            .or_else(|| self.getenv(var_base));
+
+        match res {
+            Some(res) => Ok(res),
+            None => Err("could not get environment variable".to_string()),
+        }
+    }
+
+    fn envflags(&self, name: &str) -> Vec<String> {
+        self.get_var(name)
+            .unwrap_or(String::new())
+            .split(|c: char| c.is_whitespace())
+            .filter(|s| !s.is_empty())
+            .map(|s| s.to_string())
+            .collect()
+    }
+
+    fn env_tool(&self, name: &str) -> Option<(String, Vec<String>)> {
+        self.get_var(name).ok().map(|tool| {
+            let whitelist = ["ccache", "distcc"];
+            for t in whitelist.iter() {
+                if tool.starts_with(t) && tool[t.len()..].starts_with(" ") {
+                    return (t.to_string(), vec![tool[t.len()..].trim_left().to_string()]);
+                }
+            }
+            (tool, Vec::new())
+        })
+    }
+
+    /// Returns the default C++ standard library for the current target: `libc++`
+    /// for OS X and `libstdc++` for anything else.
+    fn get_cpp_link_stdlib(&self) -> Option<String> {
+        self.cpp_link_stdlib.clone().unwrap_or_else(|| {
+            let target = self.get_target();
+            if target.contains("msvc") {
+                None
+            } else if target.contains("darwin") {
+                Some("c++".to_string())
+            } else if target.contains("freebsd") {
+                Some("c++".to_string())
+            } else {
+                Some("stdc++".to_string())
+            }
+        })
+    }
+
+    fn get_ar(&self) -> PathBuf {
+        self.archiver
+            .clone()
+            .or_else(|| self.get_var("AR").map(PathBuf::from).ok())
+            .unwrap_or_else(|| {
+                if self.get_target().contains("android") {
+                    PathBuf::from(format!("{}-ar", self.get_target().replace("armv7", "arm")))
+                } else if self.get_target().contains("emscripten") {
+                    PathBuf::from("emar")
+                } else {
+                    PathBuf::from("ar")
+                }
+            })
+    }
+
+    fn get_target(&self) -> String {
+        self.target.clone().unwrap_or_else(|| self.getenv_unwrap("TARGET"))
+    }
+
+    fn get_host(&self) -> String {
+        self.host.clone().unwrap_or_else(|| self.getenv_unwrap("HOST"))
+    }
+
+    fn get_opt_level(&self) -> String {
+        self.opt_level.as_ref().cloned().unwrap_or_else(|| self.getenv_unwrap("OPT_LEVEL"))
+    }
+
+    fn get_debug(&self) -> bool {
+        self.debug.unwrap_or_else(|| self.getenv_unwrap("PROFILE") == "debug")
+    }
+
+    fn get_out_dir(&self) -> PathBuf {
+        self.out_dir.clone().unwrap_or_else(|| env::var_os("OUT_DIR").map(PathBuf::from).unwrap())
+    }
+
+    fn getenv(&self, v: &str) -> Option<String> {
+        let r = env::var(v).ok();
+        self.print(&format!("{} = {:?}", v, r));
+        r
+    }
+
+    fn getenv_unwrap(&self, v: &str) -> String {
+        match self.getenv(v) {
+            Some(s) => s,
+            None => fail(&format!("environment variable `{}` not defined", v)),
+        }
+    }
+
+    fn print(&self, s: &str) {
+        if self.cargo_metadata {
+            println!("{}", s);
+        }
+    }
+}
+
+impl Tool {
+    fn new(path: PathBuf) -> Tool {
+        // Try to detect family of the tool from its name, falling back to Gnu.
+        let family = if let Some(fname) = path.file_name().and_then(|p| p.to_str()) {
+            if fname.contains("clang") {
+                ToolFamily::Clang
+            } else if fname.contains("cl") {
+                ToolFamily::Msvc
+            } else {
+                ToolFamily::Gnu
+            }
+        } else {
+            ToolFamily::Gnu
+        };
+        Tool {
+            path: path,
+            args: Vec::new(),
+            env: Vec::new(),
+            family: family
+        }
+    }
+
+    /// Converts this compiler into a `Command` that's ready to be run.
+    ///
+    /// This is useful for when the compiler needs to be executed and the
+    /// command returned will already have the initial arguments and environment
+    /// variables configured.
+    pub fn to_command(&self) -> Command {
+        let mut cmd = Command::new(&self.path);
+        cmd.args(&self.args);
+        for &(ref k, ref v) in self.env.iter() {
+            cmd.env(k, v);
+        }
+        cmd
+    }
+
+    /// Returns the path for this compiler.
+    ///
+    /// Note that this may not be a path to a file on the filesystem, e.g. "cc",
+    /// but rather something which will be resolved when a process is spawned.
+    pub fn path(&self) -> &Path {
+        &self.path
+    }
+
+    /// Returns the default set of arguments to the compiler needed to produce
+    /// executables for the target this compiler generates.
+    pub fn args(&self) -> &[OsString] {
+        &self.args
+    }
+
+    /// Returns the set of environment variables needed for this compiler to
+    /// operate.
+    ///
+    /// This is typically only used for MSVC compilers currently.
+    pub fn env(&self) -> &[(OsString, OsString)] {
+        &self.env
+    }
+}
+
+fn run(cmd: &mut Command, program: &str) {
+    let (mut child, print) = spawn(cmd, program);
+    let status = child.wait().expect("failed to wait on child process");
+    print.join().unwrap();
+    println!("{:?}", status);
+    if !status.success() {
+        fail(&format!("command did not execute successfully, got: {}", status));
+    }
+}
+
+fn run_output(cmd: &mut Command, program: &str) -> Vec<u8> {
+    cmd.stdout(Stdio::piped());
+    let (mut child, print) = spawn(cmd, program);
+    let mut stdout = vec![];
+    child.stdout.take().unwrap().read_to_end(&mut stdout).unwrap();
+    let status = child.wait().expect("failed to wait on child process");
+    print.join().unwrap();
+    println!("{:?}", status);
+    if !status.success() {
+        fail(&format!("command did not execute successfully, got: {}", status));
+    }
+    return stdout
+}
+
+fn spawn(cmd: &mut Command, program: &str) -> (Child, JoinHandle<()>) {
+    println!("running: {:?}", cmd);
+
+    // Capture the standard error coming from these programs, and write it out
+    // with cargo:warning= prefixes. Note that this is a bit wonky to avoid
+    // requiring the output to be UTF-8, we instead just ship bytes from one
+    // location to another.
+    match cmd.stderr(Stdio::piped()).spawn() {
+        Ok(mut child) => {
+            let stderr = BufReader::new(child.stderr.take().unwrap());
+            let print = thread::spawn(move || {
+                for line in stderr.split(b'\n').filter_map(|l| l.ok()) {
+                    print!("cargo:warning=");
+                    std::io::stdout().write_all(&line).unwrap();
+                    println!("");
+                }
+            });
+            (child, print)
+        }
+        Err(ref e) if e.kind() == io::ErrorKind::NotFound => {
+            let extra = if cfg!(windows) {
+                " (see https://github.com/alexcrichton/gcc-rs#compile-time-requirements \
+                   for help)"
+            } else {
+                ""
+            };
+            fail(&format!("failed to execute command: {}\nIs `{}` \
+                           not installed?{}",
+                          e,
+                          program,
+                          extra));
+        }
+        Err(e) => fail(&format!("failed to execute command: {}", e)),
+    }
+}
+
+fn fail(s: &str) -> ! {
+    println!("\n\n{}\n\n", s);
+    panic!()
+}
diff --git a/gcc/src/registry.rs b/gcc/src/registry.rs
new file mode 100644
index 0000000..a452723
--- /dev/null
+++ b/gcc/src/registry.rs
@@ -0,0 +1,190 @@
+// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use std::ffi::{OsString, OsStr};
+use std::io;
+use std::ops::RangeFrom;
+use std::os::raw;
+use std::os::windows::prelude::*;
+
+pub struct RegistryKey(Repr);
+
+type HKEY = *mut u8;
+type DWORD = u32;
+type LPDWORD = *mut DWORD;
+type LPCWSTR = *const u16;
+type LPWSTR = *mut u16;
+type LONG = raw::c_long;
+type PHKEY = *mut HKEY;
+type PFILETIME = *mut u8;
+type LPBYTE = *mut u8;
+type REGSAM = u32;
+
+const ERROR_SUCCESS: DWORD = 0;
+const ERROR_NO_MORE_ITEMS: DWORD = 259;
+const HKEY_LOCAL_MACHINE: HKEY = 0x80000002 as HKEY;
+const REG_SZ: DWORD = 1;
+const KEY_READ: DWORD = 0x20019;
+const KEY_WOW64_32KEY: DWORD = 0x200;
+
+#[link(name = "advapi32")]
+extern "system" {
+    fn RegOpenKeyExW(key: HKEY,
+                     lpSubKey: LPCWSTR,
+                     ulOptions: DWORD,
+                     samDesired: REGSAM,
+                     phkResult: PHKEY)
+                     -> LONG;
+    fn RegEnumKeyExW(key: HKEY,
+                     dwIndex: DWORD,
+                     lpName: LPWSTR,
+                     lpcName: LPDWORD,
+                     lpReserved: LPDWORD,
+                     lpClass: LPWSTR,
+                     lpcClass: LPDWORD,
+                     lpftLastWriteTime: PFILETIME)
+                     -> LONG;
+    fn RegQueryValueExW(hKey: HKEY,
+                        lpValueName: LPCWSTR,
+                        lpReserved: LPDWORD,
+                        lpType: LPDWORD,
+                        lpData: LPBYTE,
+                        lpcbData: LPDWORD)
+                        -> LONG;
+    fn RegCloseKey(hKey: HKEY) -> LONG;
+}
+
+struct OwnedKey(HKEY);
+
+enum Repr {
+    Const(HKEY),
+    Owned(OwnedKey),
+}
+
+pub struct Iter<'a> {
+    idx: RangeFrom<DWORD>,
+    key: &'a RegistryKey,
+}
+
+unsafe impl Sync for Repr {}
+unsafe impl Send for Repr {}
+
+pub static LOCAL_MACHINE: RegistryKey = RegistryKey(Repr::Const(HKEY_LOCAL_MACHINE));
+
+impl RegistryKey {
+    fn raw(&self) -> HKEY {
+        match self.0 {
+            Repr::Const(val) => val,
+            Repr::Owned(ref val) => val.0,
+        }
+    }
+
+    pub fn open(&self, key: &OsStr) -> io::Result<RegistryKey> {
+        let key = key.encode_wide().chain(Some(0)).collect::<Vec<_>>();
+        let mut ret = 0 as *mut _;
+        let err = unsafe {
+            RegOpenKeyExW(self.raw(),
+                          key.as_ptr(),
+                          0,
+                          KEY_READ | KEY_WOW64_32KEY,
+                          &mut ret)
+        };
+        if err == ERROR_SUCCESS as LONG {
+            Ok(RegistryKey(Repr::Owned(OwnedKey(ret))))
+        } else {
+            Err(io::Error::from_raw_os_error(err as i32))
+        }
+    }
+
+    pub fn iter(&self) -> Iter {
+        Iter {
+            idx: 0..,
+            key: self,
+        }
+    }
+
+    pub fn query_str(&self, name: &str) -> io::Result<OsString> {
+        let name: &OsStr = name.as_ref();
+        let name = name.encode_wide().chain(Some(0)).collect::<Vec<_>>();
+        let mut len = 0;
+        let mut kind = 0;
+        unsafe {
+            let err = RegQueryValueExW(self.raw(),
+                                       name.as_ptr(),
+                                       0 as *mut _,
+                                       &mut kind,
+                                       0 as *mut _,
+                                       &mut len);
+            if err != ERROR_SUCCESS as LONG {
+                return Err(io::Error::from_raw_os_error(err as i32));
+            }
+            if kind != REG_SZ {
+                return Err(io::Error::new(io::ErrorKind::Other, "registry key wasn't a string"));
+            }
+
+            // The length here is the length in bytes, but we're using wide
+            // characters so we need to be sure to halve it for the capacity
+            // passed in.
+            let mut v = Vec::with_capacity(len as usize / 2);
+            let err = RegQueryValueExW(self.raw(),
+                                       name.as_ptr(),
+                                       0 as *mut _,
+                                       0 as *mut _,
+                                       v.as_mut_ptr() as *mut _,
+                                       &mut len);
+            if err != ERROR_SUCCESS as LONG {
+                return Err(io::Error::from_raw_os_error(err as i32));
+            }
+            v.set_len(len as usize / 2);
+
+            // Some registry keys may have a terminating nul character, but
+            // we're not interested in that, so chop it off if it's there.
+            if v[v.len() - 1] == 0 {
+                v.pop();
+            }
+            Ok(OsString::from_wide(&v))
+        }
+    }
+}
+
+impl Drop for OwnedKey {
+    fn drop(&mut self) {
+        unsafe {
+            RegCloseKey(self.0);
+        }
+    }
+}
+
+impl<'a> Iterator for Iter<'a> {
+    type Item = io::Result<OsString>;
+
+    fn next(&mut self) -> Option<io::Result<OsString>> {
+        self.idx.next().and_then(|i| unsafe {
+            let mut v = Vec::with_capacity(256);
+            let mut len = v.capacity() as DWORD;
+            let ret = RegEnumKeyExW(self.key.raw(),
+                                    i,
+                                    v.as_mut_ptr(),
+                                    &mut len,
+                                    0 as *mut _,
+                                    0 as *mut _,
+                                    0 as *mut _,
+                                    0 as *mut _);
+            if ret == ERROR_NO_MORE_ITEMS as LONG {
+                None
+            } else if ret != ERROR_SUCCESS as LONG {
+                Some(Err(io::Error::from_raw_os_error(ret as i32)))
+            } else {
+                v.set_len(len as usize);
+                Some(Ok(OsString::from_wide(&v)))
+            }
+        })
+    }
+}
diff --git a/gcc/src/windows_registry.rs b/gcc/src/windows_registry.rs
new file mode 100644
index 0000000..08b1df5
--- /dev/null
+++ b/gcc/src/windows_registry.rs
@@ -0,0 +1,424 @@
+// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+//! A helper module to probe the Windows Registry when looking for
+//! windows-specific tools.
+
+use std::process::Command;
+
+use Tool;
+
+macro_rules! otry {
+    ($expr:expr) => (match $expr {
+        Some(val) => val,
+        None => return None,
+    })
+}
+
+/// Attempts to find a tool within an MSVC installation using the Windows
+/// registry as a point to search from.
+///
+/// The `target` argument is the target that the tool should work for (e.g.
+/// compile or link for) and the `tool` argument is the tool to find (e.g.
+/// `cl.exe` or `link.exe`).
+///
+/// This function will return `None` if the tool could not be found, or it will
+/// return `Some(cmd)` which represents a command that's ready to execute the
+/// tool with the appropriate environment variables set.
+///
+/// Note that this function always returns `None` for non-MSVC targets.
+pub fn find(target: &str, tool: &str) -> Option<Command> {
+    find_tool(target, tool).map(|c| c.to_command())
+}
+
+/// Similar to the `find` function above, this function will attempt the same
+/// operation (finding a MSVC tool in a local install) but instead returns a
+/// `Tool` which may be introspected.
+#[cfg(not(windows))]
+pub fn find_tool(_target: &str, _tool: &str) -> Option<Tool> {
+    None
+}
+
+/// Documented above.
+#[cfg(windows)]
+pub fn find_tool(target: &str, tool: &str) -> Option<Tool> {
+    use std::env;
+    use std::ffi::OsString;
+    use std::mem;
+    use std::path::{Path, PathBuf};
+    use registry::{RegistryKey, LOCAL_MACHINE};
+
+    struct MsvcTool {
+        tool: PathBuf,
+        libs: Vec<PathBuf>,
+        path: Vec<PathBuf>,
+        include: Vec<PathBuf>,
+    }
+
+    impl MsvcTool {
+        fn new(tool: PathBuf) -> MsvcTool {
+            MsvcTool {
+                tool: tool,
+                libs: Vec::new(),
+                path: Vec::new(),
+                include: Vec::new(),
+            }
+        }
+
+        fn into_tool(self) -> Tool {
+            let MsvcTool { tool, libs, path, include } = self;
+            let mut tool = Tool::new(tool.into());
+            add_env(&mut tool, "LIB", libs);
+            add_env(&mut tool, "PATH", path);
+            add_env(&mut tool, "INCLUDE", include);
+            tool
+        }
+    }
+
+    // This logic is all tailored for MSVC, if we're not that then bail out
+    // early.
+    if !target.contains("msvc") {
+        return None;
+    }
+
+    // Looks like msbuild isn't located in the same location as other tools like
+    // cl.exe and lib.exe. To handle this we probe for it manually with
+    // dedicated registry keys.
+    if tool.contains("msbuild") {
+        return find_msbuild(target);
+    }
+
+    // If VCINSTALLDIR is set, then someone's probably already run vcvars and we
+    // should just find whatever that indicates.
+    if env::var_os("VCINSTALLDIR").is_some() {
+        return env::var_os("PATH")
+            .and_then(|path| env::split_paths(&path).map(|p| p.join(tool)).find(|p| p.exists()))
+            .map(|path| Tool::new(path.into()));
+    }
+
+    // Ok, if we're here, now comes the fun part of the probing. Default shells
+    // or shells like MSYS aren't really configured to execute `cl.exe` and the
+    // various compiler tools shipped as part of Visual Studio. Here we try to
+    // first find the relevant tool, then we also have to be sure to fill in
+    // environment variables like `LIB`, `INCLUDE`, and `PATH` to ensure that
+    // the tool is actually usable.
+
+    return find_msvc_latest(tool, target, "15.0")
+        .or_else(|| find_msvc_latest(tool, target, "14.0"))
+        .or_else(|| find_msvc_12(tool, target))
+        .or_else(|| find_msvc_11(tool, target));
+
+    // For MSVC 14 or newer we need to find the Universal CRT as well as either
+    // the Windows 10 SDK or Windows 8.1 SDK.
+    fn find_msvc_latest(tool: &str, target: &str, ver: &str) -> Option<Tool> {
+        let vcdir = otry!(get_vc_dir(ver));
+        let mut tool = otry!(get_tool(tool, &vcdir, target));
+        let sub = otry!(lib_subdir(target));
+        let (ucrt, ucrt_version) = otry!(get_ucrt_dir());
+
+        let ucrt_include = ucrt.join("include").join(&ucrt_version);
+        tool.include.push(ucrt_include.join("ucrt"));
+
+        let ucrt_lib = ucrt.join("lib").join(&ucrt_version);
+        tool.libs.push(ucrt_lib.join("ucrt").join(sub));
+
+        if let Some((sdk, version)) = get_sdk10_dir() {
+            tool.path.push(sdk.join("bin").join(sub));
+            let sdk_lib = sdk.join("lib").join(&version);
+            tool.libs.push(sdk_lib.join("um").join(sub));
+            let sdk_include = sdk.join("include").join(&version);
+            tool.include.push(sdk_include.join("um"));
+            tool.include.push(sdk_include.join("winrt"));
+            tool.include.push(sdk_include.join("shared"));
+        } else if let Some(sdk) = get_sdk81_dir() {
+            tool.path.push(sdk.join("bin").join(sub));
+            let sdk_lib = sdk.join("lib").join("winv6.3");
+            tool.libs.push(sdk_lib.join("um").join(sub));
+            let sdk_include = sdk.join("include");
+            tool.include.push(sdk_include.join("um"));
+            tool.include.push(sdk_include.join("winrt"));
+            tool.include.push(sdk_include.join("shared"));
+        } else {
+            return None;
+        }
+        Some(tool.into_tool())
+    }
+
+    // For MSVC 12 we need to find the Windows 8.1 SDK.
+    fn find_msvc_12(tool: &str, target: &str) -> Option<Tool> {
+        let vcdir = otry!(get_vc_dir("12.0"));
+        let mut tool = otry!(get_tool(tool, &vcdir, target));
+        let sub = otry!(lib_subdir(target));
+        let sdk81 = otry!(get_sdk81_dir());
+        tool.path.push(sdk81.join("bin").join(sub));
+        let sdk_lib = sdk81.join("lib").join("winv6.3");
+        tool.libs.push(sdk_lib.join("um").join(sub));
+        let sdk_include = sdk81.join("include");
+        tool.include.push(sdk_include.join("shared"));
+        tool.include.push(sdk_include.join("um"));
+        tool.include.push(sdk_include.join("winrt"));
+        Some(tool.into_tool())
+    }
+
+    // For MSVC 11 we need to find the Windows 8 SDK.
+    fn find_msvc_11(tool: &str, target: &str) -> Option<Tool> {
+        let vcdir = otry!(get_vc_dir("11.0"));
+        let mut tool = otry!(get_tool(tool, &vcdir, target));
+        let sub = otry!(lib_subdir(target));
+        let sdk8 = otry!(get_sdk8_dir());
+        tool.path.push(sdk8.join("bin").join(sub));
+        let sdk_lib = sdk8.join("lib").join("win8");
+        tool.libs.push(sdk_lib.join("um").join(sub));
+        let sdk_include = sdk8.join("include");
+        tool.include.push(sdk_include.join("shared"));
+        tool.include.push(sdk_include.join("um"));
+        tool.include.push(sdk_include.join("winrt"));
+        Some(tool.into_tool())
+    }
+
+    fn add_env(tool: &mut Tool, env: &str, paths: Vec<PathBuf>) {
+        let prev = env::var_os(env).unwrap_or(OsString::new());
+        let prev = env::split_paths(&prev);
+        let new = paths.into_iter().chain(prev);
+        tool.env.push((env.to_string().into(), env::join_paths(new).unwrap()));
+    }
+
+    // Given a possible MSVC installation directory, we look for the linker and
+    // then add the MSVC library path.
+    fn get_tool(tool: &str, path: &Path, target: &str) -> Option<MsvcTool> {
+        bin_subdir(target)
+            .into_iter()
+            .map(|(sub, host)| (path.join("bin").join(sub).join(tool), path.join("bin").join(host)))
+            .filter(|&(ref path, _)| path.is_file())
+            .map(|(path, host)| {
+                let mut tool = MsvcTool::new(path);
+                tool.path.push(host);
+                tool
+            })
+            .filter_map(|mut tool| {
+                let sub = otry!(vc_lib_subdir(target));
+                tool.libs.push(path.join("lib").join(sub));
+                tool.include.push(path.join("include"));
+                let atlmfc_path = path.join("atlmfc");
+                if atlmfc_path.exists() {
+                    tool.libs.push(atlmfc_path.join("lib").join(sub));
+                    tool.include.push(atlmfc_path.join("include"));
+                }
+                Some(tool)
+            })
+            .next()
+    }
+
+    // To find MSVC we look in a specific registry key for the version we are
+    // trying to find.
+    fn get_vc_dir(ver: &str) -> Option<PathBuf> {
+        let key = r"SOFTWARE\Microsoft\VisualStudio\SxS\VC7";
+        let key = otry!(LOCAL_MACHINE.open(key.as_ref()).ok());
+        let path = otry!(key.query_str(ver).ok());
+        Some(path.into())
+    }
+
+    // To find the Universal CRT we look in a specific registry key for where
+    // all the Universal CRTs are located and then sort them asciibetically to
+    // find the newest version. While this sort of sorting isn't ideal,  it is
+    // what vcvars does so that's good enough for us.
+    //
+    // Returns a pair of (root, version) for the ucrt dir if found
+    fn get_ucrt_dir() -> Option<(PathBuf, String)> {
+        let key = r"SOFTWARE\Microsoft\Windows Kits\Installed Roots";
+        let key = otry!(LOCAL_MACHINE.open(key.as_ref()).ok());
+        let root = otry!(key.query_str("KitsRoot10").ok());
+        let readdir = otry!(Path::new(&root).join("lib").read_dir().ok());
+        let max_libdir = otry!(readdir.filter_map(|dir| dir.ok())
+            .map(|dir| dir.path())
+            .filter(|dir| {
+                dir.components()
+                    .last()
+                    .and_then(|c| c.as_os_str().to_str())
+                    .map(|c| c.starts_with("10.") && dir.join("ucrt").is_dir())
+                    .unwrap_or(false)
+            })
+            .max());
+        let version = max_libdir.components().last().unwrap();
+        let version = version.as_os_str().to_str().unwrap().to_string();
+        Some((root.into(), version))
+    }
+
+    // Vcvars finds the correct version of the Windows 10 SDK by looking
+    // for the include `um\Windows.h` because sometimes a given version will
+    // only have UCRT bits without the rest of the SDK. Since we only care about
+    // libraries and not includes, we instead look for `um\x64\kernel32.lib`.
+    // Since the 32-bit and 64-bit libraries are always installed together we
+    // only need to bother checking x64, making this code a tiny bit simpler.
+    // Like we do for the Universal CRT, we sort the possibilities
+    // asciibetically to find the newest one as that is what vcvars does.
+    fn get_sdk10_dir() -> Option<(PathBuf, String)> {
+        let key = r"SOFTWARE\Microsoft\Microsoft SDKs\Windows\v10.0";
+        let key = otry!(LOCAL_MACHINE.open(key.as_ref()).ok());
+        let root = otry!(key.query_str("InstallationFolder").ok());
+        let readdir = otry!(Path::new(&root).join("lib").read_dir().ok());
+        let mut dirs = readdir.filter_map(|dir| dir.ok())
+            .map(|dir| dir.path())
+            .collect::<Vec<_>>();
+        dirs.sort();
+        let dir = otry!(dirs.into_iter()
+            .rev()
+            .filter(|dir| dir.join("um").join("x64").join("kernel32.lib").is_file())
+            .next());
+        let version = dir.components().last().unwrap();
+        let version = version.as_os_str().to_str().unwrap().to_string();
+        Some((root.into(), version))
+    }
+
+    // Interestingly there are several subdirectories, `win7` `win8` and
+    // `winv6.3`. Vcvars seems to only care about `winv6.3` though, so the same
+    // applies to us. Note that if we were targetting kernel mode drivers
+    // instead of user mode applications, we would care.
+    fn get_sdk81_dir() -> Option<PathBuf> {
+        let key = r"SOFTWARE\Microsoft\Microsoft SDKs\Windows\v8.1";
+        let key = otry!(LOCAL_MACHINE.open(key.as_ref()).ok());
+        let root = otry!(key.query_str("InstallationFolder").ok());
+        Some(root.into())
+    }
+
+    fn get_sdk8_dir() -> Option<PathBuf> {
+        let key = r"SOFTWARE\Microsoft\Microsoft SDKs\Windows\v8.0";
+        let key = otry!(LOCAL_MACHINE.open(key.as_ref()).ok());
+        let root = otry!(key.query_str("InstallationFolder").ok());
+        Some(root.into())
+    }
+
+    const PROCESSOR_ARCHITECTURE_INTEL: u16 = 0;
+    const PROCESSOR_ARCHITECTURE_AMD64: u16 = 9;
+    const X86: u16 = PROCESSOR_ARCHITECTURE_INTEL;
+    const X86_64: u16 = PROCESSOR_ARCHITECTURE_AMD64;
+
+    // When choosing the tool to use, we have to choose the one which matches
+    // the target architecture. Otherwise we end up in situations where someone
+    // on 32-bit Windows is trying to cross compile to 64-bit and it tries to
+    // invoke the native 64-bit compiler which won't work.
+    //
+    // For the return value of this function, the first member of the tuple is
+    // the folder of the tool we will be invoking, while the second member is
+    // the folder of the host toolchain for that tool which is essential when
+    // using a cross linker. We return a Vec since on x64 there are often two
+    // linkers that can target the architecture we desire. The 64-bit host
+    // linker is preferred, and hence first, due to 64-bit allowing it more
+    // address space to work with and potentially being faster.
+    fn bin_subdir(target: &str) -> Vec<(&'static str, &'static str)> {
+        let arch = target.split('-').next().unwrap();
+        match (arch, host_arch()) {
+            ("i586", X86) | ("i686", X86) => vec![("", "")],
+            ("i586", X86_64) | ("i686", X86_64) => vec![("amd64_x86", "amd64"), ("", "")],
+            ("x86_64", X86) => vec![("x86_amd64", "")],
+            ("x86_64", X86_64) => vec![("amd64", "amd64"), ("x86_amd64", "")],
+            ("arm", X86) => vec![("x86_arm", "")],
+            ("arm", X86_64) => vec![("amd64_arm", "amd64"), ("x86_arm", "")],
+            _ => vec![],
+        }
+    }
+
+    fn lib_subdir(target: &str) -> Option<&'static str> {
+        let arch = target.split('-').next().unwrap();
+        match arch {
+            "i586" | "i686" => Some("x86"),
+            "x86_64" => Some("x64"),
+            "arm" => Some("arm"),
+            _ => None,
+        }
+    }
+
+    // MSVC's x86 libraries are not in a subfolder
+    fn vc_lib_subdir(target: &str) -> Option<&'static str> {
+        let arch = target.split('-').next().unwrap();
+        match arch {
+            "i586" | "i686" => Some(""),
+            "x86_64" => Some("amd64"),
+            "arm" => Some("arm"),
+            _ => None,
+        }
+    }
+
+    #[allow(bad_style)]
+    fn host_arch() -> u16 {
+        type DWORD = u32;
+        type WORD = u16;
+        type LPVOID = *mut u8;
+        type DWORD_PTR = usize;
+
+        #[repr(C)]
+        struct SYSTEM_INFO {
+            wProcessorArchitecture: WORD,
+            _wReserved: WORD,
+            _dwPageSize: DWORD,
+            _lpMinimumApplicationAddress: LPVOID,
+            _lpMaximumApplicationAddress: LPVOID,
+            _dwActiveProcessorMask: DWORD_PTR,
+            _dwNumberOfProcessors: DWORD,
+            _dwProcessorType: DWORD,
+            _dwAllocationGranularity: DWORD,
+            _wProcessorLevel: WORD,
+            _wProcessorRevision: WORD,
+        }
+
+        extern "system" {
+            fn GetNativeSystemInfo(lpSystemInfo: *mut SYSTEM_INFO);
+        }
+
+        unsafe {
+            let mut info = mem::zeroed();
+            GetNativeSystemInfo(&mut info);
+            info.wProcessorArchitecture
+        }
+    }
+
+    // Given a registry key, look at all the sub keys and find the one which has
+    // the maximal numeric value.
+    //
+    // Returns the name of the maximal key as well as the opened maximal key.
+    fn max_version(key: &RegistryKey) -> Option<(OsString, RegistryKey)> {
+        let mut max_vers = 0;
+        let mut max_key = None;
+        for subkey in key.iter().filter_map(|k| k.ok()) {
+            let val = subkey.to_str()
+                .and_then(|s| s.trim_left_matches("v").replace(".", "").parse().ok());
+            let val = match val {
+                Some(s) => s,
+                None => continue,
+            };
+            if val > max_vers {
+                if let Ok(k) = key.open(&subkey) {
+                    max_vers = val;
+                    max_key = Some((subkey, k));
+                }
+            }
+        }
+        max_key
+    }
+
+    // see http://stackoverflow.com/questions/328017/path-to-msbuild
+    fn find_msbuild(target: &str) -> Option<Tool> {
+        let key = r"SOFTWARE\Microsoft\MSBuild\ToolsVersions";
+        LOCAL_MACHINE.open(key.as_ref())
+            .ok()
+            .and_then(|key| {
+                max_version(&key).and_then(|(_vers, key)| key.query_str("MSBuildToolsPath").ok())
+            })
+            .map(|path| {
+                let mut path = PathBuf::from(path);
+                path.push("MSBuild.exe");
+                let mut tool = Tool::new(path);
+                if target.contains("x86_64") {
+                    tool.env.push(("Platform".into(), "X64".into()));
+                }
+                tool
+            })
+    }
+}