Bump version to 2.2.0 and hide MaxEncodedLen behind an additional c…

…rate feature (#282)

* Hide `trait MaxEncodedLen` behind the new `max-encoded-len` feature

* Bump versions to 2.2.0

* Shuffle some cfg feature directives

* ci: Test also using the new feature flag

.gitlab-ci.yml

@@ -81,7 +81,7 @@ test-rust-stable:
   stage:                           test
   <<:                              *docker-env
   script:
-    - time cargo +stable test --verbose --all --features bit-vec,generic-array,derive
+    - time cargo +stable test --verbose --all --features bit-vec,generic-array,derive,max-encoded-len
     - sccache -s
 
 test-rust-stable-no_derive:

Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "parity-scale-codec"
 description = "SCALE - Simple Concatenating Aggregated Little Endians"
-version = "2.2.0-rc.3"
+version = "2.2.0"
 authors = ["Parity Technologies <admin@parity.io>"]
 license = "Apache-2.0"
 repository = "https://github.com/paritytech/parity-scale-codec"
@@ -11,7 +11,7 @@ edition = "2018"
 [dependencies]
 arrayvec = { version = "0.7", default-features = false }
 serde = { version = "1.0.102", optional = true }
-parity-scale-codec-derive = { path = "derive", version = "2.2.0-rc.3", default-features = false, optional = true }
+parity-scale-codec-derive = { path = "derive", version = "2.2.0", default-features = false, optional = true }
 bitvec = { version = "0.20.1", default-features = false, features = ["alloc"], optional = true }
 byte-slice-cast = { version = "1.0.0", default-features = false }
 generic-array = { version = "0.14.4", optional = true }
@@ -21,7 +21,7 @@ impl-trait-for-tuples = "0.2.1"
 [dev-dependencies]
 criterion = "0.3.0"
 serde_derive = { version = "1.0" }
-parity-scale-codec-derive = { path = "derive", version = "2.2.0-rc.1", default-features = false }
+parity-scale-codec-derive = { path = "derive", default-features = false }
 quickcheck = "1.0"
 trybuild = "1.0.42"
 
@@ -39,6 +39,11 @@ std = ["serde", "bitvec/std", "byte-slice-cast/std", "chain-error"]
 bit-vec = ["bitvec"]
 fuzz = ["std", "arbitrary"]
 
+# Enables the new `MaxEncodedLen` trait.
+# NOTE: This is still considered experimental and is exempt from the usual
+# SemVer guarantees. We do not guarantee no code breakage when using this.
+max-encoded-len = ["parity-scale-codec-derive/max-encoded-len"]
+
 # Make error fully descriptive with chaining error message.
 # Should not be used in a constrained environment.
 chain-error = []

derive/Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "parity-scale-codec-derive"
 description = "Serialization and deserialization derive macro for Parity SCALE Codec"
-version = "2.2.0-rc.3"
+version = "2.2.0"
 authors = ["Parity Technologies <admin@parity.io>"]
 license = "Apache-2.0"
 edition = "2018"
@@ -17,3 +17,9 @@ proc-macro-crate = "1.0.0"
 
 [dev-dependencies]
 parity-scale-codec = { path = ".." }
+
+[features]
+# Enables the new `MaxEncodedLen` trait.
+# NOTE: This is still considered experimental and is exempt from the usual
+# SemVer guarantees. We do not guarantee no code breakage when using this.
+max-encoded-len = []

derive/src/lib.rs

@@ -336,6 +336,7 @@ pub fn compact_as_derive(input: proc_macro::TokenStream) -> proc_macro::TokenStr
 }
 
 /// Derive `MaxEncodedLen`.
+#[cfg(feature = "max-encoded-len")]
 #[proc_macro_derive(MaxEncodedLen, attributes(max_encoded_len_mod))]
 pub fn derive_max_encoded_len(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
 	max_encoded_len::derive_max_encoded_len(input)

derive/src/max_encoded_len.rs

@@ -13,6 +13,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+#![cfg(feature = "max-encoded-len")]
+
 use crate::utils::{self, codec_crate_path, custom_mel_trait_bound};
 use quote::{quote, quote_spanned};
 use syn::{

src/lib.rs

@@ -281,6 +281,7 @@ mod depth_limit;
 mod encode_append;
 mod encode_like;
 mod error;
+#[cfg(feature = "max-encoded-len")]
 mod max_encoded_len;
 
 pub use self::error::Error;
@@ -297,6 +298,7 @@ pub use self::decode_all::DecodeAll;
 pub use self::depth_limit::DecodeLimit;
 pub use self::encode_append::EncodeAppend;
 pub use self::encode_like::{EncodeLike, Ref};
+#[cfg(feature = "max-encoded-len")]
 pub use max_encoded_len::MaxEncodedLen;
 /// Derive macro for [`MaxEncodedLen`][max_encoded_len::MaxEncodedLen].
 ///
@@ -341,5 +343,5 @@ pub use max_encoded_len::MaxEncodedLen;
 /// #[codec(crate = $crate::codec)]
 /// struct Example;
 /// ```
-#[cfg(feature = "derive")]
+#[cfg(all(feature = "derive", feature = "max-encoded-len"))]
 pub use parity_scale_codec_derive::MaxEncodedLen;