derive(Debug) on unions.

Related #282

3 files changed, 72 insertions, 1 deletions

diff --git a/src/gen.rs b/src/gen.rs
index 851f1830..3e9934f9 100644
--- a/src/gen.rs
+++ b/src/gen.rs
@@ -671,7 +671,22 @@ fn cunion_to_rs(ctx: &mut GenCtx, name: String, derive_debug: bool, layout: Layo
         empty_generics()
     );
     let union_id = rust_type_id(ctx, name.clone());
-    let union_attrs = vec!(mk_repr_attr(ctx, layout), mk_deriving_copy_attr(ctx, false));
+    let union_attrs = {
+        let mut attrs = vec!(mk_repr_attr(ctx, layout), mk_deriving_copy_attr(ctx, false));
+        if derive_debug {
+            let can_derive_debug = members.iter()
+                .all(|member| match member {
+                    &CompMember::Field(ref f) |
+                    &CompMember::CompField(_, ref f) => f.ty.can_derive_debug(),
+                    _ => true
+                });
+            if can_derive_debug {
+                attrs.push(mk_deriving_debug_attr(ctx))
+            }
+        }
+        attrs
+    };
+
     let union_def = mk_item(ctx, union_id, def, ast::Visibility::Public, union_attrs);
 
     let union_impl = ast::ItemKind::Impl(
diff --git a/tests/test_struct.rs b/tests/test_struct.rs
index 4539be83..2360f208 100644
--- a/tests/test_struct.rs
+++ b/tests/test_struct.rs
@@ -132,6 +132,7 @@ fn with_anon_union() {
         }
         #[repr(C)]
         #[derive(Copy)]
+        #[derive(Debug)]
         pub struct Union_Unnamed1 {
             pub _bindgen_data_: [u32; 1usize],
         }
diff --git a/tests/test_union.rs b/tests/test_union.rs
index 2e1869ac..f35e325a 100644
--- a/tests/test_union.rs
+++ b/tests/test_union.rs
@@ -5,6 +5,7 @@ fn with_anon_struct() {
     assert_bind_eq(Default::default(), "headers/union_with_anon_struct.h", "
         #[repr(C)]
         #[derive(Copy)]
+        #[derive(Debug)]
         pub struct Union_foo {
             pub _bindgen_data_: [u32; 2usize],
         }
@@ -41,6 +42,7 @@ fn with_anon_struct_bitfield() {
     assert_bind_eq(Default::default(), "headers/union_with_anon_struct_bitfield.h", "
         #[repr(C)]
         #[derive(Copy)]
+        #[derive(Debug)]
         pub struct Union_foo {
             pub _bindgen_data_: [u32; 1usize],
         }
@@ -67,6 +69,7 @@ fn with_anon_union() {
     assert_bind_eq(Default::default(), "headers/union_with_anon_union.h", "
         #[repr(C)]
         #[derive(Copy)]
+        #[derive(Debug)]
         pub struct Union_foo {
             pub _bindgen_data_: [u32; 1usize],
         }
@@ -84,6 +87,7 @@ fn with_anon_union() {
         }
         #[repr(C)]
         #[derive(Copy)]
+        #[derive(Debug)]
         pub struct Union_Unnamed1 {
             pub _bindgen_data_: [u32; 1usize],
         }
@@ -111,6 +115,7 @@ fn with_anon_unnamed_struct() {
     assert_bind_eq(Default::default(), "headers/union_with_anon_unnamed_struct.h", "
         #[repr(C)]
         #[derive(Copy)]
+        #[derive(Debug)]
         pub struct Union_pixel {
             pub _bindgen_data_: [u32; 1usize],
         }
@@ -150,6 +155,7 @@ fn with_anon_unnamed_union() {
     assert_bind_eq(Default::default(), "headers/union_with_anon_unnamed_union.h", "
         #[repr(C)]
         #[derive(Copy)]
+        #[derive(Debug)]
         pub struct Union_foo {
             pub _bindgen_data_: [u32; 1usize],
         }
@@ -181,6 +187,7 @@ fn with_nesting() {
     assert_bind_eq(Default::default(), "headers/union_with_nesting.h", "
         #[repr(C)]
         #[derive(Copy)]
+        #[derive(Debug)]
         pub struct Union_foo {
             pub _bindgen_data_: [u32; 1usize],
         }
@@ -214,3 +221,51 @@ fn with_nesting() {
         }
     ");
 }
+
+#[test]
+fn with_derive_debug() {
+    assert_bind_eq(Default::default(), "headers/union_with_big_member.h", "
+        #[repr(C)]
+        #[derive(Copy)]
+        pub struct Union_WithBigArray {
+            pub _bindgen_data_: [u32; 33usize],
+        }
+        impl Union_WithBigArray {
+            pub unsafe fn a(&mut self) -> *mut ::std::os::raw::c_int {
+                let raw: *mut u8 = ::std::mem::transmute(&self._bindgen_data_);
+                ::std::mem::transmute(raw.offset(0))
+            }
+            pub unsafe fn b(&mut self) -> *mut [::std::os::raw::c_int; 33usize] {
+                let raw: *mut u8 = ::std::mem::transmute(&self._bindgen_data_);
+                ::std::mem::transmute(raw.offset(0))
+            }
+        }
+        impl ::std::clone::Clone for Union_WithBigArray {
+            fn clone(&self) -> Self { *self }
+        }
+        impl ::std::default::Default for Union_WithBigArray {
+            fn default() -> Self { unsafe { ::std::mem::zeroed() } }
+        }
+        #[repr(C)]
+        #[derive(Copy)]
+        pub struct Union_WithBigMember {
+            pub _bindgen_data_: [u32; 33usize],
+        }
+        impl Union_WithBigMember {
+            pub unsafe fn a(&mut self) -> *mut ::std::os::raw::c_int {
+                let raw: *mut u8 = ::std::mem::transmute(&self._bindgen_data_);
+                ::std::mem::transmute(raw.offset(0))
+            }
+            pub unsafe fn b(&mut self) -> *mut Union_WithBigArray {
+                let raw: *mut u8 = ::std::mem::transmute(&self._bindgen_data_);
+                ::std::mem::transmute(raw.offset(0))
+            }
+        }
+        impl ::std::clone::Clone for Union_WithBigMember {
+            fn clone(&self) -> Self { *self }
+        }
+        impl ::std::default::Default for Union_WithBigMember {
+            fn default() -> Self { unsafe { ::std::mem::zeroed() } }
+        }
+    ");
+}