Readme stuff

Author: nagisa

README.md

@@ -0,0 +1,52 @@
+Ever wanted to build “native” assembly stuff in your cargo build scripts… something gcc crate
+cannot quite handle yet?  Welcome to llvm_build_utils which provides a convenient API to pack your
+.ll or .bc files into a ready to use archive full of machine code! It doesn’t even need LLVM
+installation and works on stable Rust¹!
+
+¹: May break between versions or be incompatible with some versions of Rust, though. We’ll try to
+document such breakages in the table below.
+
+# Compatibility table
+
+| Rustc version | This Library  |
+| ------------- | ------------- |
+| 1.8-1.11      | 0.1.0         |
+
+# Using llvm_build_utils
+
+First, you'll want to both add a build script for your crate (build.rs) and also add this crate to
+your Cargo.toml via:
+
+```toml
+[package]
+# ...
+build = "build.rs"
+
+[build-dependencies]
+llvm_build_utils = "0.1"
+```
+
+Then write your `build.rs` like this:
+
+```rust
+extern crate llvm_build_utils;
+use llvm_build_utils::*;
+
+fn main() {
+    build_archive(&[
+    ("input.ll", BuildOptions {
+        // customise how the file is built
+        ..BuildOptions::default()
+    })/*, ("input2.ll", ...
+        // more .ll files to be built into the archive in same format as first one
+    */], "libyourthing.a").expect("error happened");
+}
+```
+
+Running a `cargo build` should produce `libyourthing.a` which then may be linked to your Rust
+executable/library.
+
+# License
+
+llvm_build_utils is distributed under ISC (MIT-like) or Apache (version 2.0) license at your
+choice.

build.rs

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-use std::io::Write;
-use std::path::{Path, PathBuf};
+use std::path::PathBuf;
 use std::process::Command;
 
 fn main(){