Make multipart an optional feature (default off) (#1128)

src/async_impl/body.rs

@@ -152,6 +152,7 @@ impl Body {
         ImplStream(self)
     }
 
+    #[cfg(feature = "multipart")]
     pub(crate) fn content_length(&self) -> Option<u64> {
         match self.inner {
             Inner::Reusable(ref bytes) => Some(bytes.len() as u64),

src/async_impl/mod.rs

@@ -9,6 +9,7 @@ pub(crate) use self::decoder::Decoder;
 pub mod body;
 pub mod client;
 pub mod decoder;
+#[cfg(feature = "multipart")]
 pub mod multipart;
 pub(crate) mod request;
 mod response;

src/async_impl/request.rs

@@ -11,9 +11,12 @@ use serde_json;
 
 use super::body::Body;
 use super::client::{Client, Pending};
+#[cfg(feature = "multipart")]
 use super::multipart;
 use super::response::Response;
-use crate::header::{HeaderMap, HeaderName, HeaderValue, CONTENT_LENGTH, CONTENT_TYPE};
+use crate::header::{HeaderMap, HeaderName, HeaderValue, CONTENT_TYPE};
+#[cfg(feature = "multipart")]
+use crate::header::CONTENT_LENGTH;
 use crate::{Method, Url};
 use http::{Request as HttpRequest, request::Parts};
 
@@ -260,6 +263,7 @@ impl RequestBuilder {
     /// # Ok(())
     /// # }
     /// ```
+    #[cfg(feature = "multipart")]
     pub fn multipart(self, mut multipart: multipart::Form) -> RequestBuilder {
         let mut builder = self.header(
             CONTENT_TYPE,