1 files changed, 29 insertions, 0 deletions
diff --git a/src/tools/clippy/tests/ui/map_err.rs b/src/tools/clippy/tests/ui/map_err.rs
new file mode 100644
index 000000000..bb35ab1a1
--- /dev/null
+++ b/src/tools/clippy/tests/ui/map_err.rs
@@ -0,0 +1,29 @@
+#![warn(clippy::map_err_ignore)]
+#![allow(clippy::unnecessary_wraps)]
+use std::error::Error;
+use std::fmt;
+
+#[derive(Debug)]
+enum Errors {
+    Ignored,
+}
+
+impl Error for Errors {}
+
+impl fmt::Display for Errors {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "Error")
+    }
+}
+
+fn main() -> Result<(), Errors> {
+    let x = u32::try_from(-123_i32);
+
+    println!("{:?}", x.map_err(|_| Errors::Ignored));
+
+    // Should not warn you because you explicitly ignore the parameter
+    // using a named wildcard value
+    println!("{:?}", x.map_err(|_foo| Errors::Ignored));
+
+    Ok(())
+}