Revert #512 and #508

derive/src/max_encoded_len.rs

@@ -86,9 +86,7 @@ fn fields_length_expr(fields: &Fields, crate_path: &syn::Path) -> proc_macro2::T
 		let ty = &field.ty;
 		if utils::is_compact(field) {
 			quote_spanned! {
-				ty.span() => .saturating_add(
-					<<#ty as #crate_path::HasCompact>::Type as #crate_path::MaxEncodedLen>::max_encoded_len()
-				)
+				ty.span() => .saturating_add(<#crate_path::Compact::<#ty> as #crate_path::MaxEncodedLen>::max_encoded_len())
 			}
 		} else {
 			quote_spanned! {

src/compact.rs

@@ -16,14 +16,13 @@
 
 use arrayvec::ArrayVec;
 
-#[cfg(feature = "max-encoded-len")]
-use crate::MaxEncodedLen;
 use crate::{
 	alloc::vec::Vec,
 	codec::{Decode, Encode, EncodeAsRef, Input, Output},
 	encode_like::EncodeLike,
 	DecodeWithMemTracking, Error,
 };
+
 #[cfg(feature = "fuzz")]
 use arbitrary::Arbitrary;
 
@@ -239,24 +238,10 @@ where
 	}
 }
 
-/// Requires the presence of `MaxEncodedLen` when the `max-encoded-len` feature is active.
-// Remove this trait when the feature is removed.
-#[cfg(feature = "max-encoded-len")]
-pub trait MaybeMaxEncodedLen: MaxEncodedLen {}
-#[cfg(feature = "max-encoded-len")]
-impl<T: MaxEncodedLen> MaybeMaxEncodedLen for T {}
-
-/// Requires the presence of `MaxEncodedLen` when the `max-encoded-len` feature is active.
-// Remove this trait when the feature is removed.
-#[cfg(not(feature = "max-encoded-len"))]
-pub trait MaybeMaxEncodedLen {}
-#[cfg(not(feature = "max-encoded-len"))]
-impl<T> MaybeMaxEncodedLen for T {}
-
 /// Trait that tells you if a given type can be encoded/decoded in a compact way.
 pub trait HasCompact: Sized {
 	/// The compact type; this can be
-	type Type: for<'a> EncodeAsRef<'a, Self> + Decode + From<Self> + Into<Self> + MaybeMaxEncodedLen;
+	type Type: for<'a> EncodeAsRef<'a, Self> + Decode + From<Self> + Into<Self>;
 }
 
 impl<'a, T: 'a> EncodeAsRef<'a, T> for Compact<T>
@@ -266,21 +251,9 @@ where
 	type RefType = CompactRef<'a, T>;
 }
 
-#[cfg(feature = "max-encoded-len")]
-impl<T> MaxEncodedLen for Compact<T>
-where
-	T: CompactAs,
-	Compact<T::As>: MaxEncodedLen,
-	Compact<T>: Encode,
-{
-	fn max_encoded_len() -> usize {
-		Compact::<T::As>::max_encoded_len()
-	}
-}
-
 impl<T: 'static> HasCompact for T
 where
-	Compact<T>: for<'a> EncodeAsRef<'a, T> + Decode + From<Self> + Into<Self> + MaybeMaxEncodedLen,
+	Compact<T>: for<'a> EncodeAsRef<'a, T> + Decode + From<Self> + Into<Self>,
 {
 	type Type = Compact<T>;
 }

src/max_encoded_len.rs

@@ -51,18 +51,9 @@ macro_rules! impl_primitives {
 	};
 }
 
+impl_primitives!(u8, u16, u32, u64, u128, i8, i16, i32, i64, i128, bool);
+
 impl_primitives!(
-	u8,
-	i8,
-	u16,
-	i16,
-	u32,
-	i32,
-	u64,
-	i64,
-	u128,
-	i128,
-	bool,
 	NonZeroU8,
 	NonZeroU16,
 	NonZeroU32,

tests/max_encoded_len.rs

@@ -64,42 +64,6 @@ fn generic_max_length() {
 	assert_eq!(Generic::<u32>::max_encoded_len(), u32::max_encoded_len() * 2);
 }
 
-#[derive(Encode, MaxEncodedLen)]
-struct CompactField {
-	#[codec(compact)]
-	t: u64,
-	v: u64,
-}
-
-#[test]
-fn compact_field_max_length() {
-	assert_eq!(CompactField::max_encoded_len(), 17);
-	assert_eq!(
-		CompactField::max_encoded_len(),
-		Compact::<u64>::max_encoded_len() + u64::max_encoded_len()
-	);
-}
-
-#[derive(Encode, MaxEncodedLen)]
-struct CompactFieldGenerics<T: MaxEncodedLen> {
-	#[codec(compact)]
-	t: T,
-	v: u64,
-}
-
-#[test]
-fn compact_field_generics_max_length() {
-	assert_eq!(CompactFieldGenerics::<u64>::max_encoded_len(), CompactField::max_encoded_len());
-}
-
-#[derive(Encode, MaxEncodedLen)]
-struct CompactStruct(#[codec(compact)] u64);
-
-#[test]
-fn compact_struct_max_length() {
-	assert_eq!(CompactStruct::max_encoded_len(), Compact::<u64>::max_encoded_len());
-}
-
 #[derive(Encode, MaxEncodedLen)]
 struct TwoGenerics<T, U> {
 	t: T,

tests/max_encoded_len_ui/unsupported_variant.stderr

@@ -1,16 +1,12 @@
-error[E0277]: the trait bound `NotMel: MaxEncodedLen` is not satisfied
+error[E0599]: no function or associated item named `max_encoded_len` found for struct `NotMel` in the current scope
  --> tests/max_encoded_len_ui/unsupported_variant.rs:8:9
   |
+4 | struct NotMel;
+  | ------------- function or associated item `max_encoded_len` not found for this struct
+...
 8 |     NotMel(NotMel),
-  |            ^^^^^^ the trait `MaxEncodedLen` is not implemented for `NotMel`
+  |            ^^^^^^ function or associated item not found in `NotMel`
   |
-  = help: the following other types implement trait `MaxEncodedLen`:
-            ()
-            (TupleElement0, TupleElement1)
-            (TupleElement0, TupleElement1, TupleElement2)
-            (TupleElement0, TupleElement1, TupleElement2, TupleElement3)
-            (TupleElement0, TupleElement1, TupleElement2, TupleElement3, TupleElement4)
-            (TupleElement0, TupleElement1, TupleElement2, TupleElement3, TupleElement4, TupleElement5)
-            (TupleElement0, TupleElement1, TupleElement2, TupleElement3, TupleElement4, TupleElement5, TupleElement6)
-            (TupleElement0, TupleElement1, TupleElement2, TupleElement3, TupleElement4, TupleElement5, TupleElement6, TupleElement7)
-          and $N others
+  = help: items from traits can only be used if the trait is implemented and in scope
+  = note: the following trait defines an item `max_encoded_len`, perhaps you need to implement it:
+          candidate #1: `MaxEncodedLen`