# gcc-rs

A simple library meant to be used as a build dependency with Cargo packages in
order to build a set of C files into a static archive.

```rust
extern crate gcc;

fn main() {
    gcc::compile_library("libfoo.a", &["foo.c", "bar.c"]);
}
```

# External configuration via environment variables

To control the programs and flags used for building, the builder can set a number of different enviroment variables.
* `CFLAGS` - a series of space seperated flags passed to "gcc". Note that
             individual flags cannot currently contain spaces, so doing
             something like: "-L=foo\ bar" is not possible.
* `CC` - the actual c compiler used. Note that this is used as an exact
         executable name, so (for example) no extra flags can be passed inside
         this variable, and the builder must ensure that there aren't any
         trailing spaces. This compiler must understand the `-c` flag. For
         certain `TARGET`s, it also is assumed to know about other flags (most
         common is `-fPIC`).
* `AR` - the `ar` (archiver) executable to use to build the static library.

Each of these variables can also be supplied with certain prefixes and suffixes, in the following prioritized order:

1. `<var>_<target>` - for example, `CC_x86_64-unknown-linux-gnu`
1. `<var>_<target_with_underscores>` - for example, `CC_x86_64_unknown_linux_gnu`
1. `<build-kind>_<var>` - for example, `HOST_CC` or `TARGET_CFLAGS`
1. `<var>` - a plain `CC`, `AR` as above.

If none of these varaibles exist, gcc-rs uses built-in defaults

In addition to the the above optional environment variables, `gcc-rs` has some functions with hard requirements on some variables supplied by [cargo's build-script driver][cargo] that it has the `TARGET`, `OUT_DIR`, `OPT_LEVEL`, and `HOST` variables

[cargo]: http://doc.crates.io/build-script.html#inputs-to-the-build-script

# Windows notes

Currently use of this crate means that Windows users will require gcc to be
installed at compile-time. This is typically acquired through the
[MinGW-w64](http://mingw-w64.sourceforge.net), although we recommend installing
through [MSYS2 instead][msys2]. Make sure to install the appropriate
architecture corresponding to your installation of rustc.

[msys2]: https://github.com/rust-lang/rust/wiki/Note-getting-started-developing-Rust#windows

Once gcc is installed, it also requires that the directory containing gcc is in
the PATH environment variable.

# License

`gcc-rs` is primarily distributed under the terms of both the MIT license and
the Apache License (Version 2.0), with portions covered by various BSD-like
licenses.

See LICENSE-APACHE, and LICENSE-MIT for details.