Derive from any other trait only when deriving from Copy

It's impossible to #[derive] from any other trait when not deriving from Copy when using the newest Rust nightly. Any attempt to do that results in the following error: error: `#[derive]` can't be used on a `#[repr(packed)]` struct that does not derive Copy (error E0133) Fixes: rust-lang#2083 Signed-off-by: Michal Rostecki <vadorovsky@gmail.com>
vadorovsky · May 4, 2022 · c8bc986 · c8bc986
1 parent ee6ff69
commit c8bc986
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Showing 41 changed files with 482 additions and 126 deletions.
diff --git a/src/codegen/mod.rs b/src/codegen/mod.rs
@@ -113,14 +113,6 @@ bitflags! {
 fn derives_of_item(item: &Item, ctx: &BindgenContext) -> DerivableTraits {
     let mut derivable_traits = DerivableTraits::empty();
 
-    if item.can_derive_debug(ctx) && !item.annotations().disallow_debug() {
-        derivable_traits |= DerivableTraits::DEBUG;
-    }
-
-    if item.can_derive_default(ctx) && !item.annotations().disallow_default() {
-        derivable_traits |= DerivableTraits::DEFAULT;
-    }
-
     let all_template_params = item.all_template_params(ctx);
 
     if item.can_derive_copy(ctx) && !item.annotations().disallow_copy() {
@@ -137,26 +129,36 @@ fn derives_of_item(item: &Item, ctx: &BindgenContext) -> DerivableTraits {
             // It's not hard to fix though.
             derivable_traits |= DerivableTraits::CLONE;
         }
-    }
 
-    if item.can_derive_hash(ctx) {
-        derivable_traits |= DerivableTraits::HASH;
-    }
+        if item.can_derive_debug(ctx) && !item.annotations().disallow_debug() {
+            derivable_traits |= DerivableTraits::DEBUG;
+        }
 
-    if item.can_derive_partialord(ctx) {
-        derivable_traits |= DerivableTraits::PARTIAL_ORD;
-    }
+        if item.can_derive_default(ctx) &&
+            !item.annotations().disallow_default()
+        {
+            derivable_traits |= DerivableTraits::DEFAULT;
+        }
 
-    if item.can_derive_ord(ctx) {
-        derivable_traits |= DerivableTraits::ORD;
-    }
+        if item.can_derive_hash(ctx) {
+            derivable_traits |= DerivableTraits::HASH;
+        }
 
-    if item.can_derive_partialeq(ctx) {
-        derivable_traits |= DerivableTraits::PARTIAL_EQ;
-    }
+        if item.can_derive_partialord(ctx) {
+            derivable_traits |= DerivableTraits::PARTIAL_ORD;
+        }
 
-    if item.can_derive_eq(ctx) {
-        derivable_traits |= DerivableTraits::EQ;
+        if item.can_derive_ord(ctx) {
+            derivable_traits |= DerivableTraits::ORD;
+        }
+
+        if item.can_derive_partialeq(ctx) {
+            derivable_traits |= DerivableTraits::PARTIAL_EQ;
+        }
+
+        if item.can_derive_eq(ctx) {
+            derivable_traits |= DerivableTraits::EQ;
+        }
     }
 
     derivable_traits
@@ -4554,7 +4556,6 @@ pub mod utils {
 
         let incomplete_array_decl = quote! {
             #[repr(C)]
-            #[derive(Default)]
             pub struct __IncompleteArrayField<T>(
                 ::#prefix::marker::PhantomData<T>, [T; 0]);
         };

diff --git a/tests/expectations/tests/allowlisted_item_references_no_copy.rs b/tests/expectations/tests/allowlisted_item_references_no_copy.rs
@@ -6,7 +6,6 @@
 )]
 
 #[repr(C)]
-#[derive(Debug, Default)]
 pub struct NoCopy {
     pub _address: u8,
 }
@@ -23,8 +22,16 @@ fn bindgen_test_layout_NoCopy() {
         concat!("Alignment of ", stringify!(NoCopy))
     );
 }
+impl Default for NoCopy {
+    fn default() -> Self {
+        let mut s = ::std::mem::MaybeUninit::<Self>::uninit();
+        unsafe {
+            ::std::ptr::write_bytes(s.as_mut_ptr(), 0, 1);
+            s.assume_init()
+        }
+    }
+}
 #[repr(C)]
-#[derive(Debug, Default)]
 pub struct AllowlistMe {
     pub a: NoCopy,
 }
@@ -53,3 +60,12 @@ fn bindgen_test_layout_AllowlistMe() {
         )
     );
 }
+impl Default for AllowlistMe {
+    fn default() -> Self {
+        let mut s = ::std::mem::MaybeUninit::<Self>::uninit();
+        unsafe {
+            ::std::ptr::write_bytes(s.as_mut_ptr(), 0, 1);
+            s.assume_init()
+        }
+    }
+}
diff --git a/tests/expectations/tests/class.rs b/tests/expectations/tests/class.rs
@@ -6,7 +6,6 @@
 )]
 
 #[repr(C)]
-#[derive(Default)]
 pub struct __IncompleteArrayField<T>(::std::marker::PhantomData<T>, [T; 0]);
 impl<T> __IncompleteArrayField<T> {
     #[inline]
@@ -190,6 +189,15 @@ fn bindgen_test_layout_C_with_zero_length_array_2() {
         )
     );
 }
+impl Default for C_with_zero_length_array_2 {
+    fn default() -> Self {
+        let mut s = ::std::mem::MaybeUninit::<Self>::uninit();
+        unsafe {
+            ::std::ptr::write_bytes(s.as_mut_ptr(), 0, 1);
+            s.assume_init()
+        }
+    }
+}
 #[repr(C)]
 pub struct C_with_incomplete_array {
     pub a: ::std::os::raw::c_int,
@@ -219,7 +227,6 @@ impl Default for C_with_incomplete_array {
     }
 }
 #[repr(C)]
-#[derive(Debug, Default)]
 pub struct C_with_incomplete_array_2 {
     pub a: ::std::os::raw::c_int,
     pub incomplete_array: __IncompleteArrayField<::std::os::raw::c_char>,
@@ -237,6 +244,15 @@ fn bindgen_test_layout_C_with_incomplete_array_2() {
         concat!("Alignment of ", stringify!(C_with_incomplete_array_2))
     );
 }
+impl Default for C_with_incomplete_array_2 {
+    fn default() -> Self {
+        let mut s = ::std::mem::MaybeUninit::<Self>::uninit();
+        unsafe {
+            ::std::ptr::write_bytes(s.as_mut_ptr(), 0, 1);
+            s.assume_init()
+        }
+    }
+}
 #[repr(C)]
 pub struct C_with_zero_length_array_and_incomplete_array {
     pub a: ::std::os::raw::c_int,
@@ -273,7 +289,6 @@ impl Default for C_with_zero_length_array_and_incomplete_array {
     }
 }
 #[repr(C)]
-#[derive(Debug, Default)]
 pub struct C_with_zero_length_array_and_incomplete_array_2 {
     pub a: ::std::os::raw::c_int,
     pub zero_length_array: __IncompleteArrayField<::std::os::raw::c_char>,
@@ -300,8 +315,16 @@ fn bindgen_test_layout_C_with_zero_length_array_and_incomplete_array_2() {
         )
     );
 }
+impl Default for C_with_zero_length_array_and_incomplete_array_2 {
+    fn default() -> Self {
+        let mut s = ::std::mem::MaybeUninit::<Self>::uninit();
+        unsafe {
+            ::std::ptr::write_bytes(s.as_mut_ptr(), 0, 1);
+            s.assume_init()
+        }
+    }
+}
 #[repr(C)]
-#[derive(Debug, Default, Hash, PartialOrd, Ord, PartialEq, Eq)]
 pub struct WithDtor {
     pub b: ::std::os::raw::c_int,
 }
@@ -328,6 +351,15 @@ fn bindgen_test_layout_WithDtor() {
         )
     );
 }
+impl Default for WithDtor {
+    fn default() -> Self {
+        let mut s = ::std::mem::MaybeUninit::<Self>::uninit();
+        unsafe {
+            ::std::ptr::write_bytes(s.as_mut_ptr(), 0, 1);
+            s.assume_init()
+        }
+    }
+}
 #[repr(C)]
 pub struct IncompleteArrayNonCopiable {
     pub whatever: *mut ::std::os::raw::c_void,

diff --git a/tests/expectations/tests/class_1_0.rs b/tests/expectations/tests/class_1_0.rs
@@ -6,7 +6,6 @@
 )]
 
 #[repr(C)]
-#[derive(Default)]
 pub struct __IncompleteArrayField<T>(::std::marker::PhantomData<T>, [T; 0]);
 impl<T> __IncompleteArrayField<T> {
     #[inline]
@@ -199,7 +198,6 @@ impl Default for C_with_zero_length_array {
     }
 }
 #[repr(C)]
-#[derive(Debug, Default)]
 pub struct C_with_zero_length_array_2 {
     pub a: ::std::os::raw::c_int,
     pub zero_length_array: __IncompleteArrayField<::std::os::raw::c_char>,
@@ -243,6 +241,15 @@ fn bindgen_test_layout_C_with_zero_length_array_2() {
         )
     );
 }
+impl Default for C_with_zero_length_array_2 {
+    fn default() -> Self {
+        unsafe {
+            let mut s: Self = ::std::mem::uninitialized();
+            ::std::ptr::write_bytes(&mut s, 0, 1);
+            s
+        }
+    }
+}
 #[repr(C)]
 pub struct C_with_incomplete_array {
     pub a: ::std::os::raw::c_int,
@@ -272,7 +279,6 @@ impl Default for C_with_incomplete_array {
     }
 }
 #[repr(C)]
-#[derive(Debug, Default)]
 pub struct C_with_incomplete_array_2 {
     pub a: ::std::os::raw::c_int,
     pub incomplete_array: __IncompleteArrayField<::std::os::raw::c_char>,
@@ -290,6 +296,15 @@ fn bindgen_test_layout_C_with_incomplete_array_2() {
         concat!("Alignment of ", stringify!(C_with_incomplete_array_2))
     );
 }
+impl Default for C_with_incomplete_array_2 {
+    fn default() -> Self {
+        unsafe {
+            let mut s: Self = ::std::mem::uninitialized();
+            ::std::ptr::write_bytes(&mut s, 0, 1);
+            s
+        }
+    }
+}
 #[repr(C)]
 pub struct C_with_zero_length_array_and_incomplete_array {
     pub a: ::std::os::raw::c_int,
@@ -326,7 +341,6 @@ impl Default for C_with_zero_length_array_and_incomplete_array {
     }
 }
 #[repr(C)]
-#[derive(Debug, Default)]
 pub struct C_with_zero_length_array_and_incomplete_array_2 {
     pub a: ::std::os::raw::c_int,
     pub zero_length_array: __IncompleteArrayField<::std::os::raw::c_char>,
@@ -353,8 +367,16 @@ fn bindgen_test_layout_C_with_zero_length_array_and_incomplete_array_2() {
         )
     );
 }
+impl Default for C_with_zero_length_array_and_incomplete_array_2 {
+    fn default() -> Self {
+        unsafe {
+            let mut s: Self = ::std::mem::uninitialized();
+            ::std::ptr::write_bytes(&mut s, 0, 1);
+            s
+        }
+    }
+}
 #[repr(C)]
-#[derive(Debug, Default, Hash, PartialEq, Eq)]
 pub struct WithDtor {
     pub b: ::std::os::raw::c_int,
 }
@@ -381,6 +403,15 @@ fn bindgen_test_layout_WithDtor() {
         )
     );
 }
+impl Default for WithDtor {
+    fn default() -> Self {
+        unsafe {
+            let mut s: Self = ::std::mem::uninitialized();
+            ::std::ptr::write_bytes(&mut s, 0, 1);
+            s
+        }
+    }
+}
 #[repr(C)]
 pub struct IncompleteArrayNonCopiable {
     pub whatever: *mut ::std::os::raw::c_void,

diff --git a/tests/expectations/tests/class_with_dtor.rs b/tests/expectations/tests/class_with_dtor.rs
@@ -6,7 +6,6 @@
 )]
 
 #[repr(C)]
-#[derive(Debug, Hash, PartialEq, Eq)]
 pub struct HandleWithDtor<T> {
     pub ptr: *mut T,
     pub _phantom_0: ::std::marker::PhantomData<::std::cell::UnsafeCell<T>>,
@@ -22,7 +21,6 @@ impl<T> Default for HandleWithDtor<T> {
 }
 pub type HandleValue = HandleWithDtor<::std::os::raw::c_int>;
 #[repr(C)]
-#[derive(Debug, Hash, PartialEq, Eq)]
 pub struct WithoutDtor {
     pub shouldBeWithDtor: HandleValue,
 }

diff --git a/tests/expectations/tests/crtp.rs b/tests/expectations/tests/crtp.rs
@@ -29,12 +29,19 @@ fn bindgen_test_layout_Derived() {
     );
 }
 #[repr(C)]
-#[derive(Debug, Default)]
 pub struct BaseWithDestructor {
     pub _address: u8,
 }
+impl Default for BaseWithDestructor {
+    fn default() -> Self {
+        let mut s = ::std::mem::MaybeUninit::<Self>::uninit();
+        unsafe {
+            ::std::ptr::write_bytes(s.as_mut_ptr(), 0, 1);
+            s.assume_init()
+        }
+    }
+}
 #[repr(C)]
-#[derive(Debug, Default)]
 pub struct DerivedFromBaseWithDestructor {
     pub _address: u8,
 }
@@ -51,6 +58,15 @@ fn bindgen_test_layout_DerivedFromBaseWithDestructor() {
         concat!("Alignment of ", stringify!(DerivedFromBaseWithDestructor))
     );
 }
+impl Default for DerivedFromBaseWithDestructor {
+    fn default() -> Self {
+        let mut s = ::std::mem::MaybeUninit::<Self>::uninit();
+        unsafe {
+            ::std::ptr::write_bytes(s.as_mut_ptr(), 0, 1);
+            s.assume_init()
+        }
+    }
+}
 #[test]
 fn __bindgen_test_layout_Base_open0_Derived_close0_instantiation() {
     assert_eq!(