Bring back rustc-args

But instead of passing it to cargo with ops::CompileOptions, crate
RUSTFLAGS environment variable.

Author: onur

src/docbuilder/metadata.rs

@@ -21,6 +21,7 @@ use error::Result;
 /// all-features = true
 /// no-default-features = true
 /// default-target = "x86_64-unknown-linux-gnu"
+/// rustc-args = [ "--example-rustc-arg" ]
 /// rustdoc-args = [ "--example-rustdoc-arg" ]
 /// dependencies = [ "example-system-dependency" ]
 /// ```
@@ -44,6 +45,9 @@ pub struct Metadata {
     /// is always built on this target. You can change default target by setting this.
     pub default_target: Option<String>,
 
+    /// List of command line arguments for `rustc`.
+    pub rustc_args: Option<Vec<String>>,
+
     /// List of command line arguments for `rustdoc`.
     pub rustdoc_args: Option<Vec<String>>,
 
@@ -89,6 +93,7 @@ impl Metadata {
             all_features: false,
             no_default_features: false,
             default_target: None,
+            rustc_args: None,
             rustdoc_args: None,
             dependencies: None,
         }
@@ -115,6 +120,8 @@ impl Metadata {
                         .and_then(|v| v.as_bool()).unwrap_or(metadata.all_features);
                     metadata.default_target = table.get("default-target")
                         .and_then(|v| v.as_str()).map(|v| v.to_owned());
+                    metadata.rustc_args = table.get("rustc-args").and_then(|f| f.as_array())
+                        .and_then(|f| f.iter().map(|v| v.as_str().map(|v| v.to_owned())).collect());
                     metadata.rustdoc_args = table.get("rustdoc-args").and_then(|f| f.as_array())
                         .and_then(|f| f.iter().map(|v| v.as_str().map(|v| v.to_owned())).collect());
                     metadata.dependencies = table.get("dependencies").and_then(|f| f.as_array())
@@ -164,6 +171,10 @@ mod test {
 
         assert_eq!(metadata.default_target.unwrap(), "x86_64-unknown-linux-gnu".to_owned());
 
+        let rustc_args = metadata.rustc_args.unwrap();
+        assert_eq!(rustc_args.len(), 1);
+        assert_eq!(rustc_args[0], "--example-rustc-arg".to_owned());
+
         let rustdoc_args = metadata.rustdoc_args.unwrap();
         assert_eq!(rustdoc_args.len(), 1);
         assert_eq!(rustdoc_args[0], "--example-rustdoc-arg".to_owned());

src/utils/build_doc.rs

@@ -46,6 +46,15 @@ pub fn build_doc(name: &str, vers: Option<&str>, target: Option<&str>) -> CargoR
 
     let metadata = Metadata::from_package(&pkg).map_err(|e| human(e.description()))?;
 
+    // This is only way to pass rustc_args to cargo.
+    // CompileOptions::target_rustc_args is used only for the current crate,
+    // and since docs.rs never runs rustc on the current crate, we assume rustc_args
+    // will be used for the dependencies. That is why we are creating RUSTFLAGS environment
+    // variable instead of using target_rustc_args.
+    if let Some(rustc_args) = metadata.rustc_args {
+        env::set_var("RUSTFLAGS", rustc_args.join(" "));
+    }
+
     let opts = ops::CompileOptions {
         config: &config,
         jobs: None,