Make gzip an optional feature (default off)

src/async_impl/client.rs

@@ -97,7 +97,7 @@ impl ClientBuilder {
 
         ClientBuilder {
             config: Config {
-                gzip: true,
+                gzip: cfg!(feature = "gzip"),
                 headers,
                 #[cfg(feature = "default-tls")]
                 hostname_verification: true,
@@ -312,22 +312,45 @@ impl ClientBuilder {
         self
     }
 
-    /// Enable auto gzip decompression by checking the ContentEncoding response header.
+    /// Enable auto gzip decompression by checking the `Content-Encoding` response header.
     ///
     /// If auto gzip decompresson is turned on:
+    ///
     /// - When sending a request and if the request's headers do not already contain
     ///   an `Accept-Encoding` **and** `Range` values, the `Accept-Encoding` header is set to `gzip`.
-    ///   The body is **not** automatically compressed.
+    ///   The request body is **not** automatically compressed.
     /// - When receiving a response, if it's headers contain a `Content-Encoding` value that
     ///   equals to `gzip`, both values `Content-Encoding` and `Content-Length` are removed from the
-    ///   headers' set. The body is automatically decompressed.
+    ///   headers' set. The response body is automatically decompressed.
     ///
-    /// Default is enabled.
+    /// If the `gzip` feature is turned on, the default option is enabled.
+    ///
+    /// # Optional
+    ///
+    /// This requires the optional `gzip` feature to be enabled
+    #[cfg(feature = "gzip")]
     pub fn gzip(mut self, enable: bool) -> ClientBuilder {
         self.config.gzip = enable;
         self
     }
 
+    /// Disable auto response body gzip decompression.
+    ///
+    /// This method exists even if the optional `gzip` feature is not enabled.
+    /// This can be used to ensure a `Client` doesn't use gzip decompression
+    /// even if another dependency were to enable the optional `gzip` feature.
+    pub fn no_gzip(self) -> ClientBuilder {
+        #[cfg(feature = "gzip")]
+        {
+            self.gzip(false)
+        }
+
+        #[cfg(not(feature = "gzip"))]
+        {
+            self
+        }
+    }
+
     /// Add a `Proxy` to the list of proxies the `Client` will use.
     pub fn proxy(mut self, proxy: Proxy) -> ClientBuilder {
         self.config.proxies.push(proxy);