Auto merge of #229 - emilio:core-functions, r=fitzgen

Fix --use-core for functions, since we used the aster helper.

r? @fitzgen, @nox or anyone else?

Author: bors-servo

src/codegen/mod.rs

@@ -1489,7 +1489,8 @@ impl ToRustTy for Type {
             }
             TypeKind::Function(ref fs) => {
                 let ty = fs.to_rust_ty(ctx, item);
-                aster::AstBuilder::new().ty().option().build(ty)
+                let prefix = ctx.trait_prefix();
+                quote_ty!(ctx.ext_cx(), ::$prefix::option::Option<$ty>)
             }
             TypeKind::Array(item, len) => {
                 let inner = item.to_rust_ty(ctx);

tests/expectations/tests/use-core.rs

@@ -20,3 +20,5 @@ fn bindgen_test_layout_foo() {
 impl Clone for foo {
     fn clone(&self) -> Self { *self }
 }
+pub type fooFunction =
+    ::core::option::Option<unsafe extern "C" fn(bar: ::std::os::raw::c_int)>;

tests/headers/use-core.h

@@ -4,3 +4,5 @@ struct foo {
   int a, b;
   void* bar;
 };
+
+typedef void (*fooFunction)(int bar);