3 files changed, 69 insertions, 0 deletions
diff --git a/tests/ui/read_line_without_trim.fixed b/tests/ui/read_line_without_trim.fixed
new file mode 100644
index 00000000000..5995c8f523e
--- /dev/null
+++ b/tests/ui/read_line_without_trim.fixed
@@ -0,0 +1,19 @@
+//@run-rustfix
+
+#![allow(unused)]
+#![warn(clippy::read_line_without_trim)]
+
+fn main() {
+    let mut input = String::new();
+    std::io::stdin().read_line(&mut input).unwrap();
+    input.pop();
+    let _x: i32 = input.parse().unwrap(); // don't trigger here, newline character is popped
+
+    let mut input = String::new();
+    std::io::stdin().read_line(&mut input).unwrap();
+    let _x: i32 = input.trim_end().parse().unwrap();
+
+    let mut input = String::new();
+    std::io::stdin().read_line(&mut input).unwrap();
+    let _x = input.trim_end().parse::<i32>().unwrap();
+}
diff --git a/tests/ui/read_line_without_trim.rs b/tests/ui/read_line_without_trim.rs
new file mode 100644
index 00000000000..84527b624b6
--- /dev/null
+++ b/tests/ui/read_line_without_trim.rs
@@ -0,0 +1,19 @@
+//@run-rustfix
+
+#![allow(unused)]
+#![warn(clippy::read_line_without_trim)]
+
+fn main() {
+    let mut input = String::new();
+    std::io::stdin().read_line(&mut input).unwrap();
+    input.pop();
+    let _x: i32 = input.parse().unwrap(); // don't trigger here, newline character is popped
+
+    let mut input = String::new();
+    std::io::stdin().read_line(&mut input).unwrap();
+    let _x: i32 = input.parse().unwrap();
+
+    let mut input = String::new();
+    std::io::stdin().read_line(&mut input).unwrap();
+    let _x = input.parse::<i32>().unwrap();
+}
diff --git a/tests/ui/read_line_without_trim.stderr b/tests/ui/read_line_without_trim.stderr
new file mode 100644
index 00000000000..f0f7a61e9ff
--- /dev/null
+++ b/tests/ui/read_line_without_trim.stderr
@@ -0,0 +1,31 @@
+error: calling `.parse()` without trimming the trailing newline character
+  --> $DIR/read_line_without_trim.rs:14:25
+   |
+LL |     let _x: i32 = input.parse().unwrap();
+   |                   ----- ^^^^^^^
+   |                   |
+   |                   help: try: `input.trim_end()`
+   |
+note: call to `.read_line()` here, which leaves a trailing newline character in the buffer, which in turn will cause `.parse()` to fail
+  --> $DIR/read_line_without_trim.rs:13:5
+   |
+LL |     std::io::stdin().read_line(&mut input).unwrap();
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   = note: `-D clippy::read-line-without-trim` implied by `-D warnings`
+
+error: calling `.parse()` without trimming the trailing newline character
+  --> $DIR/read_line_without_trim.rs:18:20
+   |
+LL |     let _x = input.parse::<i32>().unwrap();
+   |              ----- ^^^^^^^^^^^^^^
+   |              |
+   |              help: try: `input.trim_end()`
+   |
+note: call to `.read_line()` here, which leaves a trailing newline character in the buffer, which in turn will cause `.parse()` to fail
+  --> $DIR/read_line_without_trim.rs:17:5
+   |
+LL |     std::io::stdin().read_line(&mut input).unwrap();
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 2 previous errors
+