Update hidapi-sys crate to 0.1.4

This change updates the hidapi-sys crate to version 0.1.4. In this
version the cc crate (the stable and renamed version of the gcc crate)
is used.

Import subrepo hidapi-sys/:hidapi-sys at c01043da72c0cac898660017e4c4115278c14369
Import subrepo cc/:cc at 500c65b03775cecf55bd358e616963bc3222acca

1 files changed, 1998 insertions, 0 deletions

diff --git a/cc/src/lib.rs b/cc/src/lib.rs
new file mode 100644
index 0000000..67d8f6f
--- /dev/null
+++ b/cc/src/lib.rs
@@ -0,0 +1,1998 @@
+//! 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]
+//! cc = "1.0"
+//! ```
+//!
+//! 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.
+//! Configuration is available through the `Build` struct.
+//!
+//! This crate will automatically detect situations such as cross compilation or
+//! other environment variables set by Cargo and will build code appropriately.
+//!
+//! The crate is not limited to C code, it can accept any source code that can
+//! be passed to a C or C++ compiler. As such, assembly files with extensions
+//! `.s` (gcc/clang) and `.asm` (MSVC) can also be compiled.
+//!
+//! [`Build`]: struct.Build.html
+//!
+//! # Parallelism
+//!
+//! To parallelize computation, enable the `parallel` feature for the crate.
+//!
+//! ```toml
+//! [build-dependencies]
+//! cc = { version = "1.0", features = ["parallel"] }
+//! ```
+//! To specify the max number of concurrent compilation jobs, set the `NUM_JOBS`
+//! environment variable to the desired amount.
+//!
+//! Cargo will also set this environment variable when executed with the `-jN` flag.
+//!
+//! If `NUM_JOBS` is not set, the `RAYON_NUM_THREADS` environment variable can
+//! also specify the build paralellism.
+//!
+//! # Examples
+//!
+//! Use the `Build` struct to compile `src/foo.c`:
+//!
+//! ```no_run
+//! extern crate cc;
+//!
+//! fn main() {
+//!     cc::Build::new()
+//!         .file("src/foo.c")
+//!         .define("FOO", Some("bar"))
+//!         .include("src")
+//!         .compile("foo");
+//! }
+//! ```
+
+#![doc(html_root_url = "https://docs.rs/cc/1.0")]
+#![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(feature = "parallel")]
+use std::sync::Mutex;
+
+// These modules are all glue to support reading the MSVC version from
+// the registry and from COM interfaces
+#[cfg(windows)]
+mod registry;
+#[cfg(windows)]
+#[macro_use]
+mod winapi;
+#[cfg(windows)]
+mod com;
+#[cfg(windows)]
+mod setup_config;
+
+pub mod windows_registry;
+
+/// A builder for compilation of a native static library.
+///
+/// A `Build` is the main type of the `cc` crate and is used to control all the
+/// various configuration options and such of a compile. You'll find more
+/// documentation on each method itself.
+#[derive(Clone, Debug)]
+pub struct Build {
+    include_directories: Vec<PathBuf>,
+    definitions: Vec<(String, Option<String>)>,
+    objects: Vec<PathBuf>,
+    flags: Vec<String>,
+    flags_supported: Vec<String>,
+    files: Vec<PathBuf>,
+    cpp: bool,
+    cpp_link_stdlib: Option<Option<String>>,
+    cpp_set_stdlib: Option<String>,
+    cuda: bool,
+    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>,
+    static_crt: Option<bool>,
+    shared_flag: Option<bool>,
+    static_flag: Option<bool>,
+    warnings_into_errors: bool,
+    warnings: bool,
+}
+
+/// Represents the types of errors that may occur while using cc-rs.
+#[derive(Clone, Debug)]
+enum ErrorKind {
+    /// Error occurred while performing I/O.
+    IOError,
+    /// Invalid architecture supplied.
+    ArchitectureInvalid,
+    /// Environment variable not found, with the var in question as extra info.
+    EnvVarNotFound,
+    /// Error occurred while using external tools (ie: invocation of compiler).
+    ToolExecError,
+    /// Error occurred due to missing external tools.
+    ToolNotFound,
+}
+
+/// Represents an internal error that occurred, with an explanation.
+#[derive(Clone, Debug)]
+pub struct Error {
+    /// Describes the kind of error that occurred.
+    kind: ErrorKind,
+    /// More explanation of error that occurred.
+    message: String,
+}
+
+impl Error {
+    fn new(kind: ErrorKind, message: &str) -> Error {
+        Error {
+            kind: kind,
+            message: message.to_owned(),
+        }
+    }
+}
+
+impl From<io::Error> for Error {
+    fn from(e: io::Error) -> Error {
+        Error::new(ErrorKind::IOError, &format!("{}", e))
+    }
+}
+
+/// 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.
+#[derive(Clone, Debug)]
+pub struct Tool {
+    path: PathBuf,
+    cc_wrapper_path: Option<PathBuf>,
+    cc_wrapper_args: Vec<OsString>,
+    args: Vec<OsString>,
+    env: Vec<(OsString, OsString)>,
+    family: ToolFamily,
+    cuda: bool,
+}
+
+/// 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, PartialEq)]
+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",
+        }
+    }
+
+    /// What the flags to enable all warnings
+    fn warnings_flags(&self) -> &'static [&'static str] {
+        static MSVC_FLAGS: &'static [&'static str] = &["/W4"];
+        static GNU_CLANG_FLAGS: &'static [&'static str] = &["-Wall", "-Wextra"];
+
+        match *self {
+            ToolFamily::Msvc => &MSVC_FLAGS,
+            ToolFamily::Gnu | ToolFamily::Clang => &GNU_CLANG_FLAGS,
+        }
+    }
+
+    /// What the flag to turn warning into errors
+    fn warnings_to_errors_flag(&self) -> &'static str {
+        match *self {
+            ToolFamily::Msvc => "/WX",
+            ToolFamily::Gnu | ToolFamily::Clang => "-Werror",
+        }
+    }
+
+    /// NVCC-specific. Device code debug info flag. This is separate from the
+    /// debug info flag passed to the C++ compiler.
+    fn nvcc_debug_flag(&self) -> &'static str {
+        match *self {
+            ToolFamily::Msvc => unimplemented!(),
+            ToolFamily::Gnu |
+            ToolFamily::Clang => "-G",
+        }
+    }
+
+    /// NVCC-specific. Redirect the following flag to the underlying C++
+    /// compiler.
+    fn nvcc_redirect_flag(&self) -> &'static str {
+        match *self {
+            ToolFamily::Msvc => unimplemented!(),
+            ToolFamily::Gnu |
+            ToolFamily::Clang => "-Xcompiler",
+        }
+    }
+}
+
+/// Represents an object.
+///
+/// This is a source file -> object file pair.
+#[derive(Clone, Debug)]
+struct Object {
+    src: PathBuf,
+    dst: PathBuf,
+}
+
+impl Object {
+    /// Create a new source file -> object file pair.
+    fn new(src: PathBuf, dst: PathBuf) -> Object {
+        Object {
+            src: src,
+            dst: dst,
+        }
+    }
+}
+
+impl Build {
+    /// Construct a new instance of a blank set of configuration.
+    ///
+    /// This builder is finished with the [`compile`] function.
+    ///
+    /// [`compile`]: struct.Build.html#method.compile
+    pub fn new() -> Build {
+        Build {
+            include_directories: Vec::new(),
+            definitions: Vec::new(),
+            objects: Vec::new(),
+            flags: Vec::new(),
+            flags_supported: Vec::new(),
+            files: Vec::new(),
+            shared_flag: None,
+            static_flag: None,
+            cpp: false,
+            cpp_link_stdlib: None,
+            cpp_set_stdlib: None,
+            cuda: false,
+            target: None,
+            host: None,
+            out_dir: None,
+            opt_level: None,
+            debug: None,
+            env: Vec::new(),
+            compiler: None,
+            archiver: None,
+            cargo_metadata: true,
+            pic: None,
+            static_crt: None,
+            warnings: true,
+            warnings_into_errors: false,
+        }
+    }
+
+    /// Add a directory to the `-I` or include path for headers
+    ///
+    /// # Example
+    ///
+    /// ```no_run
+    /// use std::path::Path;
+    ///
+    /// let library_path = Path::new("/path/to/library");
+    ///
+    /// cc::Build::new()
+    ///     .file("src/foo.c")
+    ///     .include(library_path)
+    ///     .include("src")
+    ///     .compile("foo");
+    /// ```
+    pub fn include<P: AsRef<Path>>(&mut self, dir: P) -> &mut Build {
+        self.include_directories.push(dir.as_ref().to_path_buf());
+        self
+    }
+
+    /// Specify a `-D` variable with an optional value.
+    ///
+    /// # Example
+    ///
+    /// ```no_run
+    /// cc::Build::new()
+    ///     .file("src/foo.c")
+    ///     .define("FOO", "BAR")
+    ///     .define("BAZ", None)
+    ///     .compile("foo");
+    /// ```
+    pub fn define<'a, V: Into<Option<&'a str>>>(&mut self, var: &str, val: V) -> &mut Build {
+        self.definitions.push((
+            var.to_string(),
+            val.into().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 Build {
+        self.objects.push(obj.as_ref().to_path_buf());
+        self
+    }
+
+    /// Add an arbitrary flag to the invocation of the compiler
+    ///
+    /// # Example
+    ///
+    /// ```no_run
+    /// cc::Build::new()
+    ///     .file("src/foo.c")
+    ///     .flag("-ffunction-sections")
+    ///     .compile("foo");
+    /// ```
+    pub fn flag(&mut self, flag: &str) -> &mut Build {
+        self.flags.push(flag.to_string());
+        self
+    }
+
+    fn ensure_check_file(&self) -> Result<PathBuf, Error> {
+        let out_dir = self.get_out_dir()?;
+        let src = if self.cuda {
+            assert!(self.cpp);
+            out_dir.join("flag_check.cu")
+        } else if self.cpp {
+            out_dir.join("flag_check.cpp")
+        } else {
+            out_dir.join("flag_check.c")
+        };
+
+        if !src.exists() {
+            let mut f = fs::File::create(&src)?;
+            write!(f, "int main(void) {{ return 0; }}")?;
+        }
+
+        Ok(src)
+    }
+
+    /// Run the compiler to test if it accepts the given flag.
+    ///
+    /// For a convenience method for setting flags conditionally,
+    /// see `flag_if_supported()`.
+    ///
+    /// It may return error if it's unable to run the compilier with a test file
+    /// (e.g. the compiler is missing or a write to the `out_dir` failed).
+    pub fn is_flag_supported(&self, flag: &str) -> Result<bool, Error> {
+        let out_dir = self.get_out_dir()?;
+        let src = self.ensure_check_file()?;
+        let obj = out_dir.join("flag_check");
+        let target = self.get_target()?;
+        let mut cfg = Build::new();
+        cfg.flag(flag)
+            .target(&target)
+            .opt_level(0)
+            .host(&target)
+            .debug(false)
+            .cpp(self.cpp)
+            .cuda(self.cuda);
+        let compiler = cfg.try_get_compiler()?;
+        let mut cmd = compiler.to_command();
+        command_add_output_file(&mut cmd, &obj, target.contains("msvc"), false);
+
+        // We need to explicitly tell msvc not to link and create an exe
+        // in the root directory of the crate
+        if target.contains("msvc") {
+            cmd.arg("/c");
+        }
+
+        cmd.arg(&src);
+
+        let output = cmd.output()?;
+        Ok(output.stderr.is_empty())
+    }
+
+    /// Add an arbitrary flag to the invocation of the compiler if it supports it
+    ///
+    /// # Example
+    ///
+    /// ```no_run
+    /// cc::Build::new()
+    ///     .file("src/foo.c")
+    ///     .flag_if_supported("-Wlogical-op") // only supported by GCC
+    ///     .flag_if_supported("-Wunreachable-code") // only supported by clang
+    ///     .compile("foo");
+    /// ```
+    pub fn flag_if_supported(&mut self, flag: &str) -> &mut Build {
+        self.flags_supported.push(flag.to_string());
+        self
+    }
+
+    /// Set the `-shared` flag.
+    ///
+    /// When enabled, the compiler will produce a shared object which can
+    /// then be linked with other objects to form an executable.
+    ///
+    /// # Example
+    ///
+    /// ```no_run
+    /// cc::Build::new()
+    ///     .file("src/foo.c")
+    ///     .shared_flag(true)
+    ///     .compile("libfoo.so");
+    /// ```
+
+    pub fn shared_flag(&mut self, shared_flag: bool) -> &mut Build {
+        self.shared_flag = Some(shared_flag);
+        self
+    }
+
+    /// Set the `-static` flag.
+    ///
+    /// When enabled on systems that support dynamic linking, this prevents
+    /// linking with the shared libraries.
+    ///
+    /// # Example
+    ///
+    /// ```no_run
+    /// cc::Build::new()
+    ///     .file("src/foo.c")
+    ///     .shared_flag(true)
+    ///     .static_flag(true)
+    ///     .compile("foo");
+    /// ```
+    pub fn static_flag(&mut self, static_flag: bool) -> &mut Build {
+        self.static_flag = Some(static_flag);
+        self
+    }
+
+    /// Add a file which will be compiled
+    pub fn file<P: AsRef<Path>>(&mut self, p: P) -> &mut Build {
+        self.files.push(p.as_ref().to_path_buf());
+        self
+    }
+
+    /// Add files which will be compiled
+    pub fn files<P>(&mut self, p: P) -> &mut Build
+    where
+        P: IntoIterator,
+        P::Item: AsRef<Path>,
+    {
+        for file in p.into_iter() {
+            self.file(file);
+        }
+        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 Build {
+        self.cpp = cpp;
+        self
+    }
+
+    /// Set CUDA C++ support.
+    ///
+    /// Enabling CUDA will pass the detected C/C++ toolchain as an argument to
+    /// the CUDA compiler, NVCC. NVCC itself accepts some limited GNU-like args;
+    /// any other arguments for the C/C++ toolchain will be redirected using
+    /// "-Xcompiler" flags.
+    ///
+    /// If enabled, this also implicitly enables C++ support.
+    pub fn cuda(&mut self, cuda: bool) -> &mut Build {
+        self.cuda = cuda;
+        if cuda {
+            self.cpp = true;
+        }
+        self
+    }
+
+    /// Set warnings into errors flag.
+    ///
+    /// Disabled by default.
+    ///
+    /// Warning: turning warnings into errors only make sense
+    /// if you are a developer of the crate using cc-rs.
+    /// Some warnings only appear on some architecture or
+    /// specific version of the compiler. Any user of this crate,
+    /// or any other crate depending on it, could fail during
+    /// compile time.
+    ///
+    /// # Example
+    ///
+    /// ```no_run
+    /// cc::Build::new()
+    ///     .file("src/foo.c")
+    ///     .warnings_into_errors(true)
+    ///     .compile("libfoo.a");
+    /// ```
+    pub fn warnings_into_errors(&mut self, warnings_into_errors: bool) -> &mut Build {
+        self.warnings_into_errors = warnings_into_errors;
+        self
+    }
+
+    /// Set warnings flags.
+    ///
+    /// Adds some flags:
+    /// - "/Wall" for MSVC.
+    /// - "-Wall", "-Wextra" for GNU and Clang.
+    ///
+    /// Enabled by default.
+    ///
+    /// # Example
+    ///
+    /// ```no_run
+    /// cc::Build::new()
+    ///     .file("src/foo.c")
+    ///     .warnings(false)
+    ///     .compile("libfoo.a");
+    /// ```
+    pub fn warnings(&mut self, warnings: bool) -> &mut Build {
+        self.warnings = warnings;
+        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.
+    ///
+    /// Common values:
+    /// - `stdc++` for GNU
+    /// - `c++` for Clang
+    ///
+    /// # Example
+    ///
+    /// ```no_run
+    /// cc::Build::new()
+    ///     .file("src/foo.c")
+    ///     .shared_flag(true)
+    ///     .cpp_link_stdlib("stdc++")
+    ///     .compile("libfoo.so");
+    /// ```
+    pub fn cpp_link_stdlib<'a, V: Into<Option<&'a str>>>(
+        &mut self,
+        cpp_link_stdlib: V,
+    ) -> &mut Build {
+        self.cpp_link_stdlib = Some(cpp_link_stdlib.into().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.
+    ///
+    /// Common values:
+    /// - `stdc++` for GNU
+    /// - `c++` for Clang
+    ///
+    /// # Example
+    ///
+    /// ```no_run
+    /// cc::Build::new()
+    ///     .file("src/foo.c")
+    ///     .cpp_set_stdlib("c++")
+    ///     .compile("libfoo.a");
+    /// ```
+    pub fn cpp_set_stdlib<'a, V: Into<Option<&'a str>>>(
+        &mut self,
+        cpp_set_stdlib: V,
+    ) -> &mut Build {
+        let cpp_set_stdlib = cpp_set_stdlib.into();
+        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.
+    ///
+    /// # Example
+    ///
+    /// ```no_run
+    /// cc::Build::new()
+    ///     .file("src/foo.c")
+    ///     .target("aarch64-linux-android")
+    ///     .compile("foo");
+    /// ```
+    pub fn target(&mut self, target: &str) -> &mut Build {
+        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.
+    ///
+    /// # Example
+    ///
+    /// ```no_run
+    /// cc::Build::new()
+    ///     .file("src/foo.c")
+    ///     .host("arm-linux-gnueabihf")
+    ///     .compile("foo");
+    /// ```
+    pub fn host(&mut self, host: &str) -> &mut Build {
+        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 Build {
+        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 Build {
+        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 Build {
+        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 Build {
+        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 Build {
+        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 Build {
+        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`.
+    ///
+    /// The emitted metadata is:
+    ///
+    ///  - `rustc-link-lib=static=`*compiled lib*
+    ///  - `rustc-link-search=native=`*target folder*
+    ///  - When target is MSVC, the ATL-MFC libs are added via `rustc-link-search=native=`
+    ///  - When C++ is enabled, the C++ stdlib is added via `rustc-link-lib`
+    ///
+    pub fn cargo_metadata(&mut self, cargo_metadata: bool) -> &mut Build {
+        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 Build {
+        self.pic = Some(pic);
+        self
+    }
+
+    /// Configures whether the /MT flag or the /MD flag will be passed to msvc build tools.
+    ///
+    /// This option defaults to `false`, and affect only msvc targets.
+    pub fn static_crt(&mut self, static_crt: bool) -> &mut Build {
+        self.static_crt = Some(static_crt);
+        self
+    }
+
+    #[doc(hidden)]
+    pub fn __set_env<A, B>(&mut self, a: A, b: B) -> &mut Build
+    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`
+    ///
+    /// This will return a result instead of panicing; see compile() for the complete description.
+    pub fn try_compile(&self, output: &str) -> Result<(), Error> {
+        let (lib_name, gnu_lib_name) = if output.starts_with("lib") && output.ends_with(".a") {
+            (&output[3..output.len() - 2], output.to_owned())
+        } else {
+            let mut gnu = String::with_capacity(5 + output.len());
+            gnu.push_str("lib");
+            gnu.push_str(&output);
+            gnu.push_str(".a");
+            (output, gnu)
+        };
+        let dst = self.get_out_dir()?;
+
+        let mut objects = 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().ok_or_else(|| {
+                    Error::new(ErrorKind::IOError, "Getting object file details failed.")
+                })?)
+            } else {
+                obj
+            };
+
+            match obj.parent() {
+                Some(s) => fs::create_dir_all(s)?,
+                None => {
+                    return Err(Error::new(
+                        ErrorKind::IOError,
+                        "Getting object file details failed.",
+                    ))
+                }
+            };
+
+            objects.push(Object::new(file.to_path_buf(), obj));
+        }
+        self.compile_objects(&objects)?;
+        self.assemble(lib_name, &dst.join(gnu_lib_name), &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={}", lib_name));
+        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));
+            }
+        }
+
+        Ok(())
+    }
+
+    /// Run the compiler, generating the file `output`
+    ///
+    /// The name `output` should be the name of the library.  For backwards compatibility,
+    /// the `output` may start with `lib` and end with `.a`.  The Rust compilier will create
+    /// the assembly with the lib prefix and .a extension.  MSVC will create a file without prefix,
+    /// ending with `.lib`.
+    ///
+    /// # Panics
+    ///
+    /// Panics if `output` is not formatted correctly or if one of the underlying
+    /// compiler commands fails. It can also panic if it fails reading file names
+    /// or creating directories.
+    pub fn compile(&self, output: &str) {
+        if let Err(e) = self.try_compile(output) {
+            fail(&e.message);
+        }
+    }
+
+    #[cfg(feature = "parallel")]
+    fn compile_objects(&self, objs: &[Object]) -> Result<(), Error> {
+        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.num_threads(amt);
+            }
+        }
+        drop(rayon::initialize(cfg));
+
+        let results: Mutex<Vec<Result<(), Error>>> = Mutex::new(Vec::new());
+
+        objs.par_iter().with_max_len(1).for_each(
+            |obj| {
+                let res = self.compile_object(obj);
+                results.lock().unwrap().push(res)
+            },
+        );
+
+        // Check for any errors and return the first one found.
+        for result in results.into_inner().unwrap().iter() {
+            if result.is_err() {
+                return result.clone();
+            }
+        }
+
+        Ok(())
+    }
+
+    #[cfg(not(feature = "parallel"))]
+    fn compile_objects(&self, objs: &[Object]) -> Result<(), Error> {
+        for obj in objs {
+            self.compile_object(obj)?;
+        }
+        Ok(())
+    }
+
+    fn compile_object(&self, obj: &Object) -> Result<(), Error> {
+        let is_asm = obj.src.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.try_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()
+                    .ok_or_else(|| {
+                        Error::new(ErrorKind::IOError, "Failed to get compiler path.")
+                    })?
+                    .to_string_lossy()
+                    .into_owned(),
+            )
+        };
+        command_add_output_file(&mut cmd, &obj.dst, msvc, is_asm);
+        cmd.arg(if msvc { "/c" } else { "-c" });
+        cmd.arg(&obj.src);
+
+        run(&mut cmd, &name)?;
+        Ok(())
+    }
+
+    /// This will return a result instead of panicing; see expand() for the complete description.
+    pub fn try_expand(&self) -> Result<Vec<u8>, Error> {
+        let compiler = self.try_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());
+
+        assert!(
+            self.files.len() <= 1,
+            "Expand may only be called for a single file"
+        );
+
+        for file in self.files.iter() {
+            cmd.arg(file);
+        }
+
+        let name = compiler
+            .path
+            .file_name()
+            .ok_or_else(|| {
+                Error::new(ErrorKind::IOError, "Failed to get compiler path.")
+            })?
+            .to_string_lossy()
+            .into_owned();
+
+        Ok(run_output(&mut cmd, &name)?)
+    }
+
+    /// Run the compiler, returning the macro-expanded version of the input files.
+    ///
+    /// This is only relevant for C and C++ files.
+    ///
+    /// # Panics
+    /// Panics if more than one file is present in the config, or if compiler
+    /// path has an invalid file name.
+    ///
+    /// # Example
+    /// ```no_run
+    /// let out = cc::Build::new().file("src/foo.c").expand();
+    /// ```
+    pub fn expand(&self) -> Vec<u8> {
+        match self.try_expand() {
+            Err(e) => fail(&e.message),
+            Ok(v) => v,
+        }
+    }
+
+    /// 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.
+    ///
+    /// # Panics
+    ///
+    /// Panics if an error occurred while determining the architecture.
+    pub fn get_compiler(&self) -> Tool {
+        match self.try_get_compiler() {
+            Ok(tool) => tool,
+            Err(e) => fail(&e.message),
+        }
+    }
+
+    /// Get the compiler that's in use for this configuration.
+    ///
+    /// This will return a result instead of panicing; see get_compiler() for the complete description.
+    pub fn try_get_compiler(&self) -> Result<Tool, Error> {
+        let opt_level = self.get_opt_level()?;
+        let target = self.get_target()?;
+
+        let mut cmd = self.get_base_compiler()?;
+
+        // Non-target flags
+        // If the flag is not conditioned on target variable, it belongs here :)
+        match cmd.family {
+            ToolFamily::Msvc => {
+                assert!(!self.cuda,
+                    "CUDA C++ compilation not supported for MSVC, yet... but you are welcome to implement it :)");
+
+                cmd.args.push("/nologo".into());
+
+                let crt_flag = match self.static_crt {
+                    Some(true) => "/MT",
+                    Some(false) => "/MD",
+                    None => {
+                        let features =
+                            env::var("CARGO_CFG_TARGET_FEATURE").unwrap_or(String::new());
+                        if features.contains("crt-static") {
+                            "/MT"
+                        } else {
+                            "/MD"
+                        }
+                    }
+                };
+                cmd.args.push(crt_flag.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 => {
+                // arm-linux-androideabi-gcc 4.8 shipped with Android NDK does
+                // not support '-Oz'
+                if opt_level == "z" && cmd.family != ToolFamily::Clang {
+                    cmd.args.push("-Os".into());
+                } else {
+                    cmd.args.push(format!("-O{}", opt_level).into());
+                }
+
+                cmd.push_cc_arg("-ffunction-sections".into());
+                cmd.push_cc_arg("-fdata-sections".into());
+                if self.pic.unwrap_or(!target.contains("windows-gnu")) {
+                    cmd.push_cc_arg("-fPIC".into());
+                }
+            }
+        }
+        for arg in self.envflags(if self.cpp { "CXXFLAGS" } else { "CFLAGS" }) {
+            cmd.args.push(arg.into());
+        }
+
+        if self.get_debug() {
+            if self.cuda {
+                let nvcc_debug_flag = cmd.family.nvcc_debug_flag().into();
+                cmd.args.push(nvcc_debug_flag);
+            }
+            let debug_flag = cmd.family.debug_flag().into();
+            cmd.push_cc_arg(debug_flag);
+        }
+
+        // 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 == "x86_64-unknown-linux-gnux32" {
+                    cmd.args.push("-mx32".into());
+                } else if target.contains("x86_64") || target.contains("powerpc64") {
+                    cmd.args.push("-m64".into());
+                }
+
+                if self.static_flag.is_none() && target.contains("musl") {
+                    cmd.args.push("-static".into());
+                }
+
+                // armv7 targets get to use armv7 instructions
+                if target.starts_with("armv7-") && target.contains("-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("-mthumb".into());
+                    cmd.args.push("-mfpu=vfpv3-d16".into());
+                    cmd.args.push("-mfloat-abi=softfp".into());
+                }
+
+                if target.starts_with("armv4t-unknown-linux-") {
+                    cmd.args.push("-march=armv4t".into());
+                    cmd.args.push("-marm".into());
+                    cmd.args.push("-mfloat-abi=soft".into());
+                }
+
+                if target.starts_with("armv5te-unknown-linux-") {
+                    cmd.args.push("-march=armv5te".into());
+                    cmd.args.push("-marm".into());
+                    cmd.args.push("-mfloat-abi=soft".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());
+                }
+
+                // We can guarantee some settings for FRC
+                if target.starts_with("arm-frc-") {
+                    cmd.args.push("-march=armv7-a".into());
+                    cmd.args.push("-mcpu=cortex-a9".into());
+                    cmd.args.push("-mfpu=vfpv3".into());
+                    cmd.args.push("-mfloat-abi=softfp".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.static_flag.unwrap_or(false) {
+            cmd.args.push("-static".into());
+        }
+        if self.shared_flag.unwrap_or(false) {
+            cmd.args.push("-shared".into());
+        }
+
+        if self.cpp {
+            match (self.cpp_set_stdlib.as_ref(), cmd.family) {
+                (None, _) => {}
+                (Some(stdlib), ToolFamily::Gnu) |
+                (Some(stdlib), ToolFamily::Clang) => {
+                    cmd.push_cc_arg(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());
+        }
+
+        if self.warnings {
+            for flag in cmd.family.warnings_flags().iter() {
+                cmd.push_cc_arg(flag.into());
+            }
+        }
+
+        for flag in self.flags.iter() {
+            cmd.args.push(flag.into());
+        }
+
+        for flag in self.flags_supported.iter() {
+            if self.is_flag_supported(flag).unwrap_or(false) {
+                cmd.push_cc_arg(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());
+            }
+        }
+
+        if self.warnings_into_errors {
+            let warnings_to_errors_flag = cmd.family.warnings_to_errors_flag().into();
+            cmd.push_cc_arg(warnings_to_errors_flag);
+        }
+
+        Ok(cmd)
+    }
+
+    fn msvc_macro_assembler(&self) -> Result<(Command, String), Error> {
+        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);
+        }
+
+        Ok((cmd, tool.to_string()))
+    }
+
+    fn assemble(&self, lib_name: &str, dst: &Path, objs: &[Object]) -> Result<(), Error> {
+        // 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 objects: Vec<_> = objs.iter().map(|obj| obj.dst.clone()).collect();
+        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_else(
+                        || {
+                            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);
+            match 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(_) => (),
+                Err(_) => {
+                    return Err(Error::new(
+                        ErrorKind::IOError,
+                        "Could not copy or create a hard-link to the generated lib file.",
+                    ))
+                }
+            };
+        } else {
+            let (mut ar, cmd) = self.get_ar()?;
+            run(
+                ar.arg("crs").arg(dst).args(&objects).args(&self.objects),
+                &cmd,
+            )?;
+        }
+
+        Ok(())
+    }
+
+    fn ios_flags(&self, cmd: &mut Tool) -> Result<(), Error> {
+        enum ArchSpec {
+            Device(&'static str),
+            Simulator(&'static str),
+        }
+
+        let target = self.get_target()?;
+        let arch = target.split('-').nth(0).ok_or_else(|| {
+            Error::new(
+                ErrorKind::ArchitectureInvalid,
+                "Unknown architecture for iOS target.",
+            )
+        })?;
+        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"),
+            _ => {
+                return Err(Error::new(
+                    ErrorKind::ArchitectureInvalid,
+                    "Unknown architecture 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()?
+            .stdout;
+
+        let sdk_path = match String::from_utf8(sdk_path) {
+            Ok(p) => p,
+            Err(_) => {
+                return Err(Error::new(
+                    ErrorKind::IOError,
+                    "Unable to determine iOS SDK path.",
+                ))
+            }
+        };
+
+        cmd.args.push("-isysroot".into());
+        cmd.args.push(sdk_path.trim().into());
+
+        Ok(())
+    }
+
+    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);
+        }
+        cmd
+    }
+
+    fn get_base_compiler(&self) -> Result<Tool, Error> {
+        if let Some(ref c) = self.compiler {
+            return Ok(Tool::new(c.clone()));
+        }
+        let host = self.get_host()?;
+        let target = self.get_target()?;
+        let (env, msvc, gnu, traditional) = if self.cpp {
+            ("CXX", "cl.exe", "g++", "c++")
+        } else {
+            ("CC", "cl.exe", "gcc", "cc")
+        };
+
+        // On Solaris, c++/cc unlikely to exist or be correct.
+        let default = if host.contains("solaris") { gnu } else { traditional };
+
+        let tool_opt: Option<Tool> =
+            self.env_tool(env)
+                .map(|(tool, cc, args)| {
+                    let mut t = Tool::new(PathBuf::from(tool));
+                    if let Some(cc) = cc {
+                        t.cc_wrapper_path = Some(PathBuf::from(cc));
+                    }
+                    for arg in args {
+                        t.cc_wrapper_args.push(arg.into());
+                    }
+                    t
+                })
+                .or_else(|| {
+                    if target.contains("emscripten") {
+                        let tool = if self.cpp { "em++" } else { "emcc" };
+                        // Windows uses bat file so we have to be a bit more specific
+                        if cfg!(windows) {
+                            let mut t = Tool::new(PathBuf::from("cmd"));
+                            t.args.push("/c".into());
+                            t.args.push(format!("{}.bat", tool).into());
+                            Some(t)
+                        } else {
+                            Some(Tool::new(PathBuf::from(tool)))
+                        }
+                    } else {
+                        None
+                    }
+                })
+                .or_else(|| windows_registry::find_tool(&target, "cl.exe"));
+
+        let tool = match tool_opt {
+            Some(t) => t,
+            None => {
+                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 target.contains("cloudabi") {
+                    format!("{}-{}", target, traditional)
+                } 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"),
+                        "aarch64-unknown-linux-musl" => Some("aarch64-linux-musl"),
+                        "arm-unknown-linux-gnueabi" => Some("arm-linux-gnueabi"),
+                        "armv4t-unknown-linux-gnueabi" => Some("arm-linux-gnueabi"),
+                        "armv5te-unknown-linux-gnueabi" => Some("arm-linux-gnueabi"),
+                        "arm-frc-linux-gnueabi" => Some("arm-frc-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-netbsd-eabi" => Some("arm--netbsdelf-eabi"),
+                        "armv6-unknown-netbsd-eabihf" => Some("armv6--netbsdelf-eabihf"),
+                        "armv7-unknown-linux-gnueabihf" => Some("arm-linux-gnueabihf"),
+                        "armv7-unknown-linux-musleabihf" => Some("arm-linux-musleabihf"),
+                        "armv7-unknown-netbsd-eabihf" => Some("armv7--netbsdelf-eabihf"),
+                        "i686-pc-windows-gnu" => Some("i686-w64-mingw32"),
+                        "i686-unknown-linux-musl" => Some("musl"),
+                        "i686-unknown-netbsd" => 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-linux-gnu" => Some("sparc64-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))
+            }
+        };
+
+        let tool = if self.cuda {
+            assert!(tool.args.is_empty(),
+                "CUDA compilation currently assumes empty pre-existing args");
+            let nvcc = match self.get_var("NVCC") {
+                Err(_) => "nvcc".into(),
+                Ok(nvcc) => nvcc,
+            };
+            let mut nvcc_tool = Tool::with_features(PathBuf::from(nvcc), self.cuda);
+            nvcc_tool.args.push(format!("-ccbin={}", tool.path.display()).into());
+            nvcc_tool
+        } else {
+            tool
+        };
+
+        Ok(tool)
+    }
+
+    fn get_var(&self, var_base: &str) -> Result<String, Error> {
+        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(Error::new(
+                ErrorKind::EnvVarNotFound,
+                &format!(
+                    "Could not find environment variable {}.",
+                    var_base
+                ),
+            )),
+        }
+    }
+
+    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()
+    }
+
+
+    /// Returns compiler path, optional modifier name from whitelist, and arguments vec
+    fn env_tool(&self, name: &str) -> Option<(String, Option<String>, Vec<String>)> {
+        self.get_var(name).ok().map(|tool| {
+            let whitelist = ["ccache", "distcc", "sccache"];
+
+            for t in whitelist.iter() {
+                if tool.starts_with(t) && tool[t.len()..].starts_with(' ')  {
+                    let args = tool.split_whitespace().collect::<Vec<_>>();
+
+                    return (args[1].to_string(), Some(t.to_string()), args[2..].iter().map(|s| s.to_string()).collect());
+                }
+            }
+            (tool, None, 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) -> Result<Option<String>, Error> {
+        match self.cpp_link_stdlib.clone() {
+            Some(s) => Ok(s),
+            None => {
+                let target = self.get_target()?;
+                if target.contains("msvc") {
+                    Ok(None)
+                } else if target.contains("darwin") {
+                    Ok(Some("c++".to_string()))
+                } else if target.contains("freebsd") {
+                    Ok(Some("c++".to_string()))
+                } else if target.contains("openbsd") {
+                    Ok(Some("c++".to_string()))
+                } else {
+                    Ok(Some("stdc++".to_string()))
+                }
+            }
+        }
+    }
+
+    fn get_ar(&self) -> Result<(Command, String), Error> {
+        if let Some(ref p) = self.archiver {
+            let name = p.file_name().and_then(|s| s.to_str()).unwrap_or("ar");
+            return Ok((self.cmd(p), name.to_string()));
+        }
+        if let Ok(p) = self.get_var("AR") {
+            return Ok((self.cmd(&p), p));
+        }
+        let program = if self.get_target()?.contains("android") {
+            format!("{}-ar", self.get_target()?.replace("armv7", "arm"))
+        } else if self.get_target()?.contains("emscripten") {
+            // Windows use bat files so we have to be a bit more specific
+            if cfg!(windows) {
+                let mut cmd = self.cmd("cmd");
+                cmd.arg("/c").arg("emar.bat");
+                return Ok((cmd, "emar.bat".to_string()));
+            }
+
+            "emar".to_string()
+        } else {
+            "ar".to_string()
+        };
+        Ok((self.cmd(&program), program))
+    }
+
+    fn get_target(&self) -> Result<String, Error> {
+        match self.target.clone() {
+            Some(t) => Ok(t),
+            None => Ok(self.getenv_unwrap("TARGET")?),
+        }
+    }
+
+    fn get_host(&self) -> Result<String, Error> {
+        match self.host.clone() {
+            Some(h) => Ok(h),
+            None => Ok(self.getenv_unwrap("HOST")?),
+        }
+    }
+
+    fn get_opt_level(&self) -> Result<String, Error> {
+        match self.opt_level.as_ref().cloned() {
+            Some(ol) => Ok(ol),
+            None => Ok(self.getenv_unwrap("OPT_LEVEL")?),
+        }
+    }
+
+    fn get_debug(&self) -> bool {
+        self.debug.unwrap_or_else(|| match self.getenv("DEBUG") {
+            Some(s) => s != "false",
+            None => false,
+        })
+    }
+
+    fn get_out_dir(&self) -> Result<PathBuf, Error> {
+        match self.out_dir.clone() {
+            Some(p) => Ok(p),
+            None => Ok(env::var_os("OUT_DIR").map(PathBuf::from).ok_or_else(|| {
+                Error::new(
+                    ErrorKind::EnvVarNotFound,
+                    "Environment variable OUT_DIR not defined.",
+                )
+            })?),
+        }
+    }
+
+    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) -> Result<String, Error> {
+        match self.getenv(v) {
+            Some(s) => Ok(s),
+            None => Err(Error::new(
+                ErrorKind::EnvVarNotFound,
+                &format!(
+                    "Environment variable {} not defined.",
+                    v.to_string()
+                ),
+            )),
+        }
+    }
+
+    fn print(&self, s: &str) {
+        if self.cargo_metadata {
+            println!("{}", s);
+        }
+    }
+}
+
+impl Default for Build {
+    fn default() -> Build {
+        Build::new()
+    }
+}
+
+impl Tool {
+    fn new(path: PathBuf) -> Tool {
+        Tool::with_features(path, false)
+    }
+
+    fn with_features(path: PathBuf, cuda: bool) -> 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") && !fname.contains("cloudabi") &&
+                      !fname.contains("uclibc") {
+                ToolFamily::Msvc
+            } else {
+                ToolFamily::Gnu
+            }
+        } else {
+            ToolFamily::Gnu
+        };
+        Tool {
+            path: path,
+            cc_wrapper_path: None,
+            cc_wrapper_args: Vec::new(),
+            args: Vec::new(),
+            env: Vec::new(),
+            family: family,
+            cuda: cuda,
+        }
+    }
+
+    /// Add a flag, and optionally prepend the NVCC wrapper flag "-Xcompiler".
+    ///
+    /// Currently this is only used for compiling CUDA sources, since NVCC only
+    /// accepts a limited set of GNU-like flags, and the rest must be prefixed
+    /// with a "-Xcompiler" flag to get passed to the underlying C++ compiler.
+    fn push_cc_arg(&mut self, flag: OsString) {
+        if self.cuda {
+            self.args.push(self.family.nvcc_redirect_flag().into());
+        }
+        self.args.push(flag);
+    }
+
+    /// 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 = match self.cc_wrapper_path {
+            Some(ref cc_wrapper_path) => {
+                let mut cmd = Command::new(&cc_wrapper_path);
+                cmd.arg(&self.path);
+                cmd.args(&self.cc_wrapper_args);
+                cmd
+            },
+            None => 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
+    }
+
+    /// Returns the compiler command in format of CC environment variable.
+    /// Or empty string if CC env was not present
+    ///
+    /// This is typically used by configure script
+    pub fn cc_env(&self) -> OsString {
+        match self.cc_wrapper_path {
+            Some(ref cc_wrapper_path) => {
+                let mut cc_env = cc_wrapper_path.as_os_str().to_owned();
+                cc_env.push(" ");
+                cc_env.push(self.path.to_path_buf().into_os_string());
+                for arg in self.cc_wrapper_args.iter() {
+                    cc_env.push(" ");
+                    cc_env.push(arg);
+                }
+                cc_env
+            },
+            None => {
+                OsString::from("")
+            }
+        }
+    }
+
+    /// Returns the compiler flags in format of CFLAGS environment variable.
+    /// Important here - this will not be CFLAGS from env, its internal gcc's flags to use as CFLAGS
+    /// This is typically used by configure script
+    pub fn cflags_env(&self) -> OsString {
+        let mut flags = OsString::new();
+        for (i, arg) in self.args.iter().enumerate() {
+            if i > 0 {
+                flags.push(" ");
+            }
+            flags.push(arg);
+        }
+        flags
+    }
+
+    /// Whether the tool is GNU Compiler Collection-like.
+    pub fn is_like_gnu(&self) -> bool {
+        self.family == ToolFamily::Gnu
+    }
+
+    /// Whether the tool is Clang-like.
+    pub fn is_like_clang(&self) -> bool {
+        self.family == ToolFamily::Clang
+    }
+
+    /// Whether the tool is MSVC-like.
+    pub fn is_like_msvc(&self) -> bool {
+        self.family == ToolFamily::Msvc
+    }
+}
+
+fn run(cmd: &mut Command, program: &str) -> Result<(), Error> {
+    let (mut child, print) = spawn(cmd, program)?;
+    let status = match child.wait() {
+        Ok(s) => s,
+        Err(_) => {
+            return Err(Error::new(
+                ErrorKind::ToolExecError,
+                &format!(
+                    "Failed to wait on spawned child process, command {:?} with args {:?}.",
+                    cmd,
+                    program
+                ),
+            ))
+        }
+    };
+    print.join().unwrap();
+    println!("{}", status);
+
+    if status.success() {
+        Ok(())
+    } else {
+        Err(Error::new(
+            ErrorKind::ToolExecError,
+            &format!(
+                "Command {:?} with args {:?} did not execute successfully (status code {}).",
+                cmd,
+                program,
+                status
+            ),
+        ))
+    }
+}
+
+fn run_output(cmd: &mut Command, program: &str) -> Result<Vec<u8>, Error> {
+    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 = match child.wait() {
+        Ok(s) => s,
+        Err(_) => {
+            return Err(Error::new(
+                ErrorKind::ToolExecError,
+                &format!(
+                    "Failed to wait on spawned child process, command {:?} with args {:?}.",
+                    cmd,
+                    program
+                ),
+            ))
+        }
+    };
+    print.join().unwrap();
+    println!("{}", status);
+
+    if status.success() {
+        Ok(stdout)
+    } else {
+        Err(Error::new(
+            ErrorKind::ToolExecError,
+            &format!(
+                "Command {:?} with args {:?} did not execute successfully (status code {}).",
+                cmd,
+                program,
+                status
+            ),
+        ))
+    }
+}
+
+fn spawn(cmd: &mut Command, program: &str) -> Result<(Child, JoinHandle<()>), Error> {
+    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!("");
+            });
+            Ok((child, print))
+        }
+        Err(ref e) if e.kind() == io::ErrorKind::NotFound => {
+            let extra = if cfg!(windows) {
+                " (see https://github.com/alexcrichton/cc-rs#compile-time-requirements \
+                   for help)"
+            } else {
+                ""
+            };
+            Err(Error::new(
+                ErrorKind::ToolNotFound,
+                &format!(
+                    "Failed to find tool. Is `{}` installed?{}",
+                    program,
+                    extra
+                ),
+            ))
+        }
+        Err(_) => Err(Error::new(
+            ErrorKind::ToolExecError,
+            &format!(
+                "Command {:?} with args {:?} failed to start.",
+                cmd,
+                program
+            ),
+        )),
+    }
+}
+
+fn fail(s: &str) -> ! {
+    panic!("\n\nInternal error occurred: {}\n\n", s)
+}
+
+
+fn command_add_output_file(cmd: &mut Command, dst: &Path, msvc: bool, is_asm: bool) {
+    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);
+    }
+}