Add test cases for issue 5657

Closes 5657

PR 5252 resolves 5657

Author: ytmimi

tests/source/issue_5657.rs

@@ -0,0 +1,13 @@
+// rustfmt-max_width: 80
+
+fn omg() {
+fn bar() {
+self.core
+.exchange::<LeaseBufReader<_, BUFSIZ>, _, LeaseBufWriter<_, BUFSIZ>, _>(
+device_index,
+src,
+dest,
+)
+.map_err(RequestError::from)
+}
+}

tests/target/issue_5657.rs

@@ -0,0 +1,14 @@
+// rustfmt-max_width: 80
+
+fn omg() {
+    fn bar() {
+        self.core
+            .exchange::<
+                LeaseBufReader<_, BUFSIZ>,
+                _,
+                LeaseBufWriter<_, BUFSIZ>,
+                _,
+            >(device_index, src, dest)
+            .map_err(RequestError::from)
+    }
+}