feat: in-manifest and in-lib feature documentation (#329)

cargo-features.md

@@ -158,15 +158,7 @@ The _client_ portion of transport can be blocking or async. If none is selected,
 
 ### git-protocol
 
-The _client_ portion of the protocol uses `git-transport` to communicate to a server. For it to be available, one of the following features must
-be selected.
-
-- _mutually exclusive_ 
-    - Specifying both causes a compile error, preventing the use of `--all-features`.
-    * **blocking-client**
-      * If set, blocking command implementations are available and will use the blocking version of the `git-transport` crate.
-    * **async-client**
-      * As above, but provides async implementations instead.
+Documented in [its documentation](https://docs.rs/git-protocol).
 
 ### git-object
 

git-protocol/Cargo.toml

@@ -12,11 +12,22 @@ include = ["src/**/*", "CHANGELOG.md", "!**/tests/**/*"]
 doctest = false
 
 [features]
-## Data structures implement `serde::Serialize` and `serde::Deserialize`.
-serde1 = ["serde", "bstr/serde1", "git-transport/serde1", "git-hash/serde1"]
+
+#! ### _Mutually exclusive client _
+#! The _client_ portion of the protocol uses `git-transport` to communicate to a server. For it to be available, one of the following features must
+#! be selected.
+#!
+#! Specifying both causes a compile error, preventing the use of `--all-features`.
+
+## If set, blocking command implementations are available and will use the blocking version of the `git-transport` crate.
 blocking-client = ["git-transport/blocking-client", "maybe-async/is_sync"]
+## As above, but provides async implementations instead.
 async-client = ["git-transport/async-client", "async-trait", "futures-io", "futures-lite"]
 
+#! ### Other
+## Data structures implement `serde::Serialize` and `serde::Deserialize`.
+serde1 = ["serde", "bstr/serde1", "git-transport/serde1", "git-hash/serde1"]
+
 [[test]]
 name = "blocking-client-protocol"
 path = "tests/blocking-protocol.rs"
@@ -44,10 +55,12 @@ futures-io = { version = "0.3.16", optional = true }
 futures-lite = { version  = "1.12.0", optional = true }
 maybe-async = "0.2.6"
 
+document-features = { version = "0.1.0", optional = true }
+
 [dev-dependencies]
 async-std = { version = "1.9.0", features = ["attributes"] }
 git-packetline = { path = "../git-packetline" ,version = "^0.12.3" }
 git-testtools = { path = "../tests/tools" }
 
 [package.metadata.docs.rs]
-features = ["blocking-client"]
+features = ["blocking-client", "document-features"]

git-protocol/src/lib.rs

@@ -2,6 +2,11 @@
 //!
 //! This implementation hides the transport layer, statefulness and the protocol version to the [fetch delegate][fetch::Delegate],
 //! the actual client implementation.
+//! ## Feature Flags
+#![cfg_attr(
+    feature = "document-features",
+    cfg_attr(doc, doc = ::document_features::document_features!())
+)]
 #![deny(unsafe_code)]
 #![deny(rust_2018_idioms, missing_docs)]