generate lockfile when necessary

closes #37

CHANGELOG.md

@@ -9,6 +9,11 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 
 - Support for the `arm-unknown-linux-gnueabi` target
 
+### Changed
+
+- It's no longer necessary to call `cargo generate-lockfile` before using
+  `cross` as `cross` will now take care of creating a lockfile when necessary.
+
 ## [v0.1.3] - 2017-01-01
 
 ### Changed

README.md

@@ -57,11 +57,6 @@ it.
 # Start the Docker daemon, if it's not already running
 $ sudo systemctl start docker
 
-# (ONCE PER CARGO PROJECT)
-# `cross` can't generate .lock files itself (see caveats section)
-# if compiling a library, we'll have to use Cargo to generate the lock file
-$ cargo generate-lockfile
-
 # MAGIC! This Just Works
 $ cross build --target aarch64-unknown-linux-gnu
 
@@ -116,8 +111,6 @@ worst, "hang" (never terminate).
 - `cross` will mount the Cargo project as READ ONLY. Thus, if any crate attempts
   to modify its "source", the build will fail. Well behaved crates should only
   ever write to `$OUT_DIR` and never modify `$CARGO_MANIFEST_DIR` though.
-  - This is the reason why `cross` can't generate .lock files and you have to
-    manually call `cargo generate-lockfile`.
 
 - Versions `0.7.*` and older of the `openssl` crate are NOT supported. `cross`
   supports `openssl` via the `OPENSSL_DIR` "feature", which seems to have been

ci/script.sh

@@ -23,7 +23,6 @@ main() {
                 https://github.com/rust-lang-nursery/compiler-builtins $td
 
             pushd $td
-            cargo generate-lockfile
             cross build --features c --target $TARGET
             popd
 
@@ -73,7 +72,6 @@ main() {
                 $td
 
             pushd $td
-            cargo generate-lockfile
             cross test \
                   --no-default-features \
                   --target $TARGET
@@ -86,7 +84,6 @@ main() {
             cargo init --bin --name hello $td
 
             pushd $td
-            cargo generate-lockfile
             cross run --target $TARGET
             popd
 

src/docker.rs

@@ -59,6 +59,16 @@ pub fn run(target: Target,
         Cow::from(format!("v{}", version))
     };
 
+    let cargo_lock = cargo_root.join("Cargo.lock");
+    if !cargo_lock.exists() {
+        let cargo_toml = cargo_root.join("Cargo.toml");
+        Command::new("cargo").args(&["generate-lockfile",
+                    "--manifest-path",
+                    &cargo_toml.display().to_string()])
+            .run(verbose)
+            .chain_err(|| "couldn't generate Cargo.lock")?;
+    }
+
     Command::new("docker")
         .arg("run")
         .arg("--rm")