Add false positive test for iterator method

tests/ui/auxiliary/option_helpers.rs

@@ -53,3 +53,12 @@ impl IteratorFalsePositives {
         self.foo as usize
     }
 }
+
+#[derive(Copy, Clone)]
+pub struct IteratorMethodFalsePositives;
+
+impl IteratorMethodFalsePositives {
+    pub fn filter(&self, _s: i32) -> std::vec::IntoIter<i32> {
+        unimplemented!();
+    }
+}

tests/ui/methods.rs

@@ -32,7 +32,7 @@ use std::ops::Mul;
 use std::rc::{self, Rc};
 use std::sync::{self, Arc};
 
-use option_helpers::IteratorFalsePositives;
+use option_helpers::{IteratorFalsePositives, IteratorMethodFalsePositives};
 
 struct Lt<'a> {
     foo: &'a u32,
@@ -131,6 +131,9 @@ fn filter_next() {
     // Check that we don't lint if the caller is not an `Iterator`.
     let foo = IteratorFalsePositives { foo: 0 };
     let _ = foo.filter().next();
+
+    let foo = IteratorMethodFalsePositives {};
+    let _ = foo.filter(42).next();
 }
 
 fn main() {