chore(client): place the use of new rust features behind cfg

build.rs

@@ -0,0 +1,14 @@
+extern crate rustc_version;
+use rustc_version::{version, Version};
+
+fn main() {
+
+    // Check for a minimum version to see if new rust features can be used
+    let version = version().unwrap();
+    if version >= Version::parse("1.26.0").unwrap() {
+        println!("cargo:rustc-cfg=impl_trait_available");
+    }
+    if version >= Version::parse("1.23.0").unwrap() {
+        println!("cargo:rustc-cfg=inherent_ascii");
+    }
+}