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

Signed-off-by: Emilio Cobos Álvarez <ecoal95@gmail.com>

3 files changed, 6 insertions, 1 deletions

diff --git a/src/codegen/mod.rs b/src/codegen/mod.rs
index bf6af82b..7fa8b19c 100755
--- a/src/codegen/mod.rs
+++ b/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);
diff --git a/tests/expectations/tests/use-core.rs b/tests/expectations/tests/use-core.rs
index 484105ea..b0900f5f 100644
--- a/tests/expectations/tests/use-core.rs
+++ b/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)>;
diff --git a/tests/headers/use-core.h b/tests/headers/use-core.h
index 535d2b15..42bb10d9 100644
--- a/tests/headers/use-core.h
+++ b/tests/headers/use-core.h
@@ -4,3 +4,5 @@ struct foo {
   int a, b;
   void* bar;
 };
+
+typedef void (*fooFunction)(int bar);