Let Rust derive everything but Default for large arrays in 1.47 and later

Fixes #1977 as of rust-lang/rust#74060 is available since Rust 1.47
Fixes #2041.
Closes #2070.

1 files changed, 5 insertions, 2 deletions

diff --git a/src/codegen/mod.rs b/src/codegen/mod.rs
index c70c1064..d49d3248 100644
--- a/src/codegen/mod.rs
+++ b/src/codegen/mod.rs
@@ -1503,7 +1503,8 @@ impl<'a> FieldCodegen<'a> for BitfieldUnit {
 
         // 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;
+        let mut generate_ctor = layout.size <= RUST_DERIVE_IN_ARRAY_LIMIT ||
+            ctx.options().rust_features().larger_arrays;
 
         let mut access_spec = !fields_should_be_private;
         for bf in self.bitfields() {
@@ -1512,7 +1513,9 @@ impl<'a> FieldCodegen<'a> for BitfieldUnit {
                 continue;
             }
 
-            if layout.size > RUST_DERIVE_IN_ARRAY_LIMIT {
+            if layout.size > RUST_DERIVE_IN_ARRAY_LIMIT &&
+                !ctx.options().rust_features().larger_arrays
+            {
                 continue;
             }