feat: fail build if both tls-native and tls-rustls are enabled

Cargo.toml

@@ -39,7 +39,7 @@ default = ["tls-rustls"]
 cli = ["merge", "clap"]
 merge = ["dep:merge"]
 clap = ["dep:clap"]
-# The tls-* features should be treated as mutually exclusive.
+# tls-native and tls-rustls are mutually exclusive.
 tls-native = ["reqwest/native-tls"]
 tls-rustls = ["reqwest/rustls-tls-native-roots"]
 

README.md

@@ -55,11 +55,11 @@ This crate exposes a few features for controlling dependency usage:
 - **clap** - Enables a dependency on the `clap` crate and enables parsing from
   the commandline. *This feature is disabled by default*.
 - **tls-native** - Builds with native TLS support (i.e. link against system TLS
-  library). This feature should be treated as mutually exclusive with
-  `tls-rustls`. *This features is disabled by default*.
+  library). *This feature is mutually exclusive with `tls-rustls` and it is
+  disabled by default*.
 - **tls-rustls** - Builds with Rustls support (i.e. with bundled TLS library).
-  This feature should be treated as mutually exclusive with `tls-native`. *This
-  feature is enabled by default*.
+  *This feature is mutually exclusive with `tls-native` and it is enabled by
+  default*.
 
 ## Examples
 

src/lib.rs

@@ -139,6 +139,9 @@ This crate exposes a few features for controlling dependency usage.
 #![allow(rustdoc::private_intra_doc_links)]
 #![allow(clippy::needless_raw_string_hashes)]
 
+#[cfg(all(feature = "tls-native", feature = "tls-rustls "))]
+compile_error!("features \"tls-native\" and \"tls-rustls \" cannot be enabled at the same time. Please disable one of them.");
+
 pub(crate) mod archiver;
 pub(crate) mod backend;
 pub(crate) mod blob;