Delete support for compilers without Iterator::try_for_each

serde/build.rs

@@ -16,12 +16,6 @@ fn main() {
     let target = env::var("TARGET").unwrap();
     let emscripten = target == "asmjs-unknown-emscripten" || target == "wasm32-unknown-emscripten";
 
-    // Iterator::try_for_each stabilized in Rust 1.27:
-    // https://blog.rust-lang.org/2018/06/21/Rust-1.27.html#library-stabilizations
-    if minor < 27 {
-        println!("cargo:rustc-cfg=no_iterator_try_fold");
-    }
-
     // Non-zero integers stabilized in Rust 1.28:
     // https://blog.rust-lang.org/2018/08/02/Rust-1.28.html#library-stabilizations
     if minor < 28 {

serde/src/ser/mod.rs

@@ -1279,22 +1279,9 @@ pub trait Serializer: Sized {
         I: IntoIterator,
         <I as IntoIterator>::Item: Serialize,
     {
-        let iter = iter.into_iter();
+        let mut iter = iter.into_iter();
         let mut serializer = try!(self.serialize_seq(iterator_len_hint(&iter)));
-
+        try!(iter.try_for_each(|item| serializer.serialize_element(&item)));
-        #[cfg(not(no_iterator_try_fold))]
-        {
-            let mut iter = iter;
-            try!(iter.try_for_each(|item| serializer.serialize_element(&item)));
-        }
-
-        #[cfg(no_iterator_try_fold)]
-        {
-            for item in iter {
-                try!(serializer.serialize_element(&item));
-            }
-        }
-
         serializer.end()
     }
 
@@ -1330,22 +1317,9 @@ pub trait Serializer: Sized {
         V: Serialize,
         I: IntoIterator<Item = (K, V)>,
     {
-        let iter = iter.into_iter();
+        let mut iter = iter.into_iter();
         let mut serializer = try!(self.serialize_map(iterator_len_hint(&iter)));
-
+        try!(iter.try_for_each(|(key, value)| serializer.serialize_entry(&key, &value)));
-        #[cfg(not(no_iterator_try_fold))]
-        {
-            let mut iter = iter;
-            try!(iter.try_for_each(|(key, value)| serializer.serialize_entry(&key, &value)));
-        }
-
-        #[cfg(no_iterator_try_fold)]
-        {
-            for (key, value) in iter {
-                try!(serializer.serialize_entry(&key, &value));
-            }
-        }
-
         serializer.end()
     }