codegen: Don't check large_arrays to generate bitfield ctors because they use the Default trait.

Fixes #2082

Author: emilio

src/codegen/mod.rs

@@ -1502,9 +1502,11 @@ impl<'a> FieldCodegen<'a> for BitfieldUnit {
         let mut ctor_impl = quote! {};
 
         // We cannot generate any constructor if the underlying storage can't
-        // implement AsRef<[u8]> / AsMut<[u8]> / etc.
-        let mut generate_ctor = layout.size <= RUST_DERIVE_IN_ARRAY_LIMIT ||
-            ctx.options().rust_features().larger_arrays;
+        // implement AsRef<[u8]> / AsMut<[u8]> / etc, or can't derive Default.
+        //
+        // We don't check `larger_arrays` here because Default does still have
+        // the 32 items limitation.
+        let mut generate_ctor = layout.size <= RUST_DERIVE_IN_ARRAY_LIMIT;
 
         let mut access_spec = !fields_should_be_private;
         for bf in self.bitfields() {

tests/expectations/tests/timex.rs

@@ -92,7 +92,7 @@ where
     }
 }
 #[repr(C)]
-#[derive(Copy, Clone)]
+#[derive(Debug, Copy, Clone)]
 pub struct timex {
     pub tai: ::std::os::raw::c_int,
     pub _bitfield_align_1: [u8; 0],
@@ -131,7 +131,7 @@ impl Default for timex {
     }
 }
 #[repr(C)]
-#[derive(Copy, Clone)]
+#[derive(Debug, Copy, Clone)]
 pub struct timex_named {
     pub tai: ::std::os::raw::c_int,
     pub _bitfield_align_1: [u32; 0],
@@ -171,3 +171,148 @@ impl Default for timex_named {
         }
     }
 }
+impl timex_named {
+    #[inline]
+    pub fn a(&self) -> ::std::os::raw::c_int {
+        unsafe {
+            ::std::mem::transmute(self._bitfield_1.get(0usize, 32u8) as u32)
+        }
+    }
+    #[inline]
+    pub fn set_a(&mut self, val: ::std::os::raw::c_int) {
+        unsafe {
+            let val: u32 = ::std::mem::transmute(val);
+            self._bitfield_1.set(0usize, 32u8, val as u64)
+        }
+    }
+    #[inline]
+    pub fn b(&self) -> ::std::os::raw::c_int {
+        unsafe {
+            ::std::mem::transmute(self._bitfield_1.get(32usize, 32u8) as u32)
+        }
+    }
+    #[inline]
+    pub fn set_b(&mut self, val: ::std::os::raw::c_int) {
+        unsafe {
+            let val: u32 = ::std::mem::transmute(val);
+            self._bitfield_1.set(32usize, 32u8, val as u64)
+        }
+    }
+    #[inline]
+    pub fn c(&self) -> ::std::os::raw::c_int {
+        unsafe {
+            ::std::mem::transmute(self._bitfield_1.get(64usize, 32u8) as u32)
+        }
+    }
+    #[inline]
+    pub fn set_c(&mut self, val: ::std::os::raw::c_int) {
+        unsafe {
+            let val: u32 = ::std::mem::transmute(val);
+            self._bitfield_1.set(64usize, 32u8, val as u64)
+        }
+    }
+    #[inline]
+    pub fn d(&self) -> ::std::os::raw::c_int {
+        unsafe {
+            ::std::mem::transmute(self._bitfield_1.get(96usize, 32u8) as u32)
+        }
+    }
+    #[inline]
+    pub fn set_d(&mut self, val: ::std::os::raw::c_int) {
+        unsafe {
+            let val: u32 = ::std::mem::transmute(val);
+            self._bitfield_1.set(96usize, 32u8, val as u64)
+        }
+    }
+    #[inline]
+    pub fn e(&self) -> ::std::os::raw::c_int {
+        unsafe {
+            ::std::mem::transmute(self._bitfield_1.get(128usize, 32u8) as u32)
+        }
+    }
+    #[inline]
+    pub fn set_e(&mut self, val: ::std::os::raw::c_int) {
+        unsafe {
+            let val: u32 = ::std::mem::transmute(val);
+            self._bitfield_1.set(128usize, 32u8, val as u64)
+        }
+    }
+    #[inline]
+    pub fn f(&self) -> ::std::os::raw::c_int {
+        unsafe {
+            ::std::mem::transmute(self._bitfield_1.get(160usize, 32u8) as u32)
+        }
+    }
+    #[inline]
+    pub fn set_f(&mut self, val: ::std::os::raw::c_int) {
+        unsafe {
+            let val: u32 = ::std::mem::transmute(val);
+            self._bitfield_1.set(160usize, 32u8, val as u64)
+        }
+    }
+    #[inline]
+    pub fn g(&self) -> ::std::os::raw::c_int {
+        unsafe {
+            ::std::mem::transmute(self._bitfield_1.get(192usize, 32u8) as u32)
+        }
+    }
+    #[inline]
+    pub fn set_g(&mut self, val: ::std::os::raw::c_int) {
+        unsafe {
+            let val: u32 = ::std::mem::transmute(val);
+            self._bitfield_1.set(192usize, 32u8, val as u64)
+        }
+    }
+    #[inline]
+    pub fn h(&self) -> ::std::os::raw::c_int {
+        unsafe {
+            ::std::mem::transmute(self._bitfield_1.get(224usize, 32u8) as u32)
+        }
+    }
+    #[inline]
+    pub fn set_h(&mut self, val: ::std::os::raw::c_int) {
+        unsafe {
+            let val: u32 = ::std::mem::transmute(val);
+            self._bitfield_1.set(224usize, 32u8, val as u64)
+        }
+    }
+    #[inline]
+    pub fn i(&self) -> ::std::os::raw::c_int {
+        unsafe {
+            ::std::mem::transmute(self._bitfield_1.get(256usize, 32u8) as u32)
+        }
+    }
+    #[inline]
+    pub fn set_i(&mut self, val: ::std::os::raw::c_int) {
+        unsafe {
+            let val: u32 = ::std::mem::transmute(val);
+            self._bitfield_1.set(256usize, 32u8, val as u64)
+        }
+    }
+    #[inline]
+    pub fn j(&self) -> ::std::os::raw::c_int {
+        unsafe {
+            ::std::mem::transmute(self._bitfield_1.get(288usize, 32u8) as u32)
+        }
+    }
+    #[inline]
+    pub fn set_j(&mut self, val: ::std::os::raw::c_int) {
+        unsafe {
+            let val: u32 = ::std::mem::transmute(val);
+            self._bitfield_1.set(288usize, 32u8, val as u64)
+        }
+    }
+    #[inline]
+    pub fn k(&self) -> ::std::os::raw::c_int {
+        unsafe {
+            ::std::mem::transmute(self._bitfield_1.get(320usize, 32u8) as u32)
+        }
+    }
+    #[inline]
+    pub fn set_k(&mut self, val: ::std::os::raw::c_int) {
+        unsafe {
+            let val: u32 = ::std::mem::transmute(val);
+            self._bitfield_1.set(320usize, 32u8, val as u64)
+        }
+    }
+}

tests/headers/timex.h

@@ -1,5 +1,3 @@
-// bindgen-flags: --rust-target 1.40
-
 struct timex {
 	int tai;