Fix the crate parsing order

Since cbindgen ignores the ident namespaces and the expected behavior is
to have it generate bindings for the idents declared in the root crate,
parse first the root crate and then its dependencies.

Fixes #337.

src/bindgen/parser.rs

@@ -156,9 +156,27 @@ impl<'a> Parser<'a> {
         assert!(self.lib.is_some());
         self.parsed_crates.insert(pkg.name.clone());
 
-        // Before we do anything with this crate, we must first parse all of its dependencies.
-        // This is guaranteed to terminate because the crate-graph is acyclic (and even if it
-        // wasn't, we've already marked the crate as parsed in the line above).
+        // Check if we should use cargo expand for this crate
+        if self.expand.contains(&pkg.name) {
+            return self.parse_expand_crate(pkg);
+        }
+
+        // Parse the crate before the dependencies otherwise the same-named idents we
+        // want to generate bindings for would be replaced by the ones provided
+        // by the first dependency containing it.
+        let crate_src = self.lib.as_ref().unwrap().find_crate_src(pkg);
+
+        match crate_src {
+            Some(crate_src) => self.parse_mod(pkg, crate_src.as_path())?,
+            None => {
+                // This should be an error, but is common enough to just elicit a warning
+                warn!(
+                    "Parsing crate `{}`: can't find lib.rs with `cargo metadata`.",
+                    pkg.name
+                );
+            }
+        }
+
         for (dep_pkg, cfg) in self.lib.as_ref().unwrap().dependencies(&pkg) {
             if !self.should_parse_dependency(&dep_pkg.name) {
                 continue;
@@ -175,25 +193,7 @@ impl<'a> Parser<'a> {
             }
         }
 
-        // Check if we should use cargo expand for this crate
-        if self.expand.contains(&pkg.name) {
-            return self.parse_expand_crate(pkg);
-        }
-
-        // Otherwise do our normal parse
-        let crate_src = self.lib.as_ref().unwrap().find_crate_src(pkg);
-
-        match crate_src {
-            Some(crate_src) => self.parse_mod(pkg, crate_src.as_path()),
-            None => {
-                // This should be an error, but is common enough to just elicit a warning
-                warn!(
-                    "Parsing crate `{}`: can't find lib.rs with `cargo metadata`.",
-                    pkg.name
-                );
-                Ok(())
-            }
-        }
+        Ok(())
     }
 
     fn parse_expand_crate(&mut self, pkg: &PackageRef) -> Result<(), Error> {