Add a test for #2956

Author: topecongiro

tests/source/fn-simple.rs

@@ -67,3 +67,8 @@ crate fn init() {}
 
 // #2630
 fn make_map<T, F: (Fn(&T) -> String)>(records: &Vec<T>, key_fn: F) -> HashMap<String, usize> {}
+
+// #2956
+fn bar(beans: Asdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdf, spam: bool, eggs: bool) -> bool{
+    unimplemented!();
+}

tests/target/fn-simple.rs

@@ -108,3 +108,12 @@ crate fn init() {}
 
 // #2630
 fn make_map<T, F: (Fn(&T) -> String)>(records: &Vec<T>, key_fn: F) -> HashMap<String, usize> {}
+
+// #2956
+fn bar(
+    beans: Asdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdfasdf,
+    spam: bool,
+    eggs: bool,
+) -> bool {
+    unimplemented!();
+}