Use a tempdir with cargo expand for hygenic purposes

Cargo.lock

@@ -8,6 +8,7 @@ dependencies = [
  "serde_derive 0.9.15 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_json 0.9.10 (registry+https://github.com/rust-lang/crates.io-index)",
  "syn 0.11.11 (registry+https://github.com/rust-lang/crates.io-index)",
+ "tempdir 0.3.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "toml 0.3.2 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -85,6 +86,14 @@ name = "quote"
 version = "0.3.15"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
+[[package]]
+name = "rand"
+version = "0.3.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "libc 0.2.23 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "serde"
 version = "0.9.15"
@@ -142,6 +151,14 @@ dependencies = [
  "unicode-xid 0.0.4 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "tempdir"
+version = "0.3.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "rand 0.3.15 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "term_size"
 version = "0.3.0"
@@ -202,6 +219,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum log 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)" = "5141eca02775a762cc6cd564d8d2c50f67c0ea3a372cbf1c51592b3e029e10ad"
 "checksum num-traits 0.1.37 (registry+https://github.com/rust-lang/crates.io-index)" = "e1cbfa3781f3fe73dc05321bed52a06d2d491eaa764c52335cf4399f046ece99"
 "checksum quote 0.3.15 (registry+https://github.com/rust-lang/crates.io-index)" = "7a6e920b65c65f10b2ae65c831a81a073a89edd28c7cce89475bff467ab4167a"
+"checksum rand 0.3.15 (registry+https://github.com/rust-lang/crates.io-index)" = "022e0636ec2519ddae48154b028864bdce4eaf7d35226ab8e65c611be97b189d"
 "checksum serde 0.9.15 (registry+https://github.com/rust-lang/crates.io-index)" = "34b623917345a631dc9608d5194cc206b3fe6c3554cd1c75b937e55e285254af"
 "checksum serde_codegen_internals 0.14.2 (registry+https://github.com/rust-lang/crates.io-index)" = "bc888bd283bd2420b16ad0d860e35ad8acb21941180a83a189bb2046f9d00400"
 "checksum serde_derive 0.9.15 (registry+https://github.com/rust-lang/crates.io-index)" = "978fd866f4d4872084a81ccc35e275158351d3b9fe620074e7d7504b816b74ba"
@@ -209,6 +227,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum strsim 0.6.0 (registry+https://github.com/rust-lang/crates.io-index)" = "b4d15c810519a91cf877e7e36e63fe068815c678181439f2f29e2562147c3694"
 "checksum syn 0.11.11 (registry+https://github.com/rust-lang/crates.io-index)" = "d3b891b9015c88c576343b9b3e41c2c11a51c219ef067b264bd9c8aa9b441dad"
 "checksum synom 0.11.3 (registry+https://github.com/rust-lang/crates.io-index)" = "a393066ed9010ebaed60b9eafa373d4b1baac186dd7e008555b0f702b51945b6"
+"checksum tempdir 0.3.5 (registry+https://github.com/rust-lang/crates.io-index)" = "87974a6f5c1dfb344d733055601650059a3363de2a6104819293baff662132d6"
 "checksum term_size 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "e2b6b55df3198cc93372e85dd2ed817f0e38ce8cc0f22eb32391bfad9c4bf209"
 "checksum toml 0.3.2 (registry+https://github.com/rust-lang/crates.io-index)" = "bd86ad9ebee246fdedd610e0f6d0587b754a3d81438db930a244d0480ed7878f"
 "checksum unicode-segmentation 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "a8083c594e02b8ae1654ae26f0ade5158b119bd88ad0e8227a5d8fcd72407946"

Cargo.toml

@@ -16,7 +16,7 @@ log = "0.3"
 serde = "0.9"
 serde_derive = "0.9"
 serde_json = "0.9"
-
+tempdir = "0.3"
 toml = "0.3"
 
 [dependencies.syn]

src/bindgen/cargo/cargo_expand.rs

@@ -7,6 +7,9 @@ use std::path::Path;
 use std::process::Command;
 use std::str::from_utf8;
 
+extern crate tempdir;
+use self::tempdir::TempDir;
+
 /// Use rustc to expand and pretty print the crate into a single file,
 /// removing any macros in the process.
 pub fn expand(manifest_path: &Path,
@@ -14,7 +17,13 @@ pub fn expand(manifest_path: &Path,
               version: &str) -> Result<String, String> {
     let cargo = env::var("CARGO").unwrap_or_else(|_| String::from("cargo"));
 
+    // Create a temp directory to use as a target dir for cargo expand, for
+    // hygenic purposes.
+    let target_dir = TempDir::new("cbindgen-expand")
+                             .map_err(|_| format!("couldn't create a temp target directory"))?;
+
     let mut cmd = Command::new(cargo);
+    cmd.env("CARGO_TARGET_DIR", target_dir.path());
     cmd.arg("rustc");
     cmd.arg("--frozen");
     cmd.arg("--manifest-path");