[git-protocol] build should fail if mutually exclusiive features are set

Author: Byron

Makefile

@@ -99,8 +99,6 @@ check: ## Build all code in suitable configurations
 					   && cargo check \
 					   && cargo check --features blocking-io \
 					   && cargo check --features async-io
-	cd git-protocol && cargo check --all-features \
-			   && cargo check
 	cd git-url && cargo check --all-features \
 			   && cargo check
 	cd git-features && cargo check --all-features \
@@ -123,9 +121,10 @@ check: ## Build all code in suitable configurations
 					 && cargo check --features blocking-client \
 					 && cargo check --features async-client \
 					 && cargo check --features http-client-curl
-	cd git-protocol && cargo check --all-features \
-					 && cargo check \
-					 && cargo check --features blocking-client
+	cd git-protocol && cargo check \
+					&& cargo check --features blocking-client \
+					&& cargo check --features async-client
+	cd git-protocol && if cargo check --all-features 2>/dev/null; then false; else true; fi
 	cd git-repository && cargo check --all-features \
 					 && cargo check --no-default-features
 

git-protocol/Cargo.toml

@@ -13,7 +13,7 @@ doctest = false
 
 [features]
 serde1 = ["serde", "bstr/serde1", "git-transport/serde1", "git-hash/serde1"]
-blocking-client = ["git-transport/blocking-client"]
+blocking-client = ["git-transport/blocking-client", "maybe-async/is_sync"]
 async-client = ["git-transport/async-client", "async-trait", "futures-io", "futures-lite"]
 
 [[test]]
@@ -41,8 +41,8 @@ btoi = "0.4.2"
 async-trait = { version = "0.1.50", optional = true }
 futures-io = { version = "0.3.15", optional = true }
 futures-lite = { version  = "1.12.0", optional = true }
+maybe-async = "0.2.6"
 
 [dev-dependencies]
 async-std = { version = "1.9.0", features = ["attributes"] }
-maybe-async = "0.2.6"
 git-packetline = { version = "^0.6.0", path = "../git-packetline" }

git-protocol/src/lib.rs

@@ -26,3 +26,6 @@ pub mod fetch;
 #[doc(inline)]
 #[cfg(feature = "blocking-client")]
 pub use fetch::fetch;
+
+#[cfg(all(feature = "blocking-client", feature = "async-client"))]
+compile_error!("Cannot set both 'blocking-client' and 'async-client' features as they are mutually exclusive");