1 files changed, 59 insertions, 0 deletions
diff --git a/src/tools/clippy/tests/ui/write_with_newline.rs b/src/tools/clippy/tests/ui/write_with_newline.rs
new file mode 100644
index 000000000..446d6914d
--- /dev/null
+++ b/src/tools/clippy/tests/ui/write_with_newline.rs
@@ -0,0 +1,59 @@
+// FIXME: Ideally these suggestions would be fixed via rustfix. Blocked by rust-lang/rust#53934
+// // run-rustfix
+
+#![allow(clippy::write_literal)]
+#![warn(clippy::write_with_newline)]
+
+use std::io::Write;
+
+fn main() {
+    let mut v = Vec::new();
+
+    // These should fail
+    write!(v, "Hello\n");
+    write!(v, "Hello {}\n", "world");
+    write!(v, "Hello {} {}\n", "world", "#2");
+    write!(v, "{}\n", 1265);
+    write!(v, "\n");
+
+    // These should be fine
+    write!(v, "");
+    write!(v, "Hello");
+    writeln!(v, "Hello");
+    writeln!(v, "Hello\n");
+    writeln!(v, "Hello {}\n", "world");
+    write!(v, "Issue\n{}", 1265);
+    write!(v, "{}", 1265);
+    write!(v, "\n{}", 1275);
+    write!(v, "\n\n");
+    write!(v, "like eof\n\n");
+    write!(v, "Hello {} {}\n\n", "world", "#2");
+    writeln!(v, "\ndon't\nwarn\nfor\nmultiple\nnewlines\n"); // #3126
+    writeln!(v, "\nbla\n\n"); // #3126
+
+    // Escaping
+    write!(v, "\\n"); // #3514
+    write!(v, "\\\n"); // should fail
+    write!(v, "\\\\n");
+
+    // Raw strings
+    write!(v, r"\n"); // #3778
+
+    // Literal newlines should also fail
+    write!(
+        v,
+        "
+"
+    );
+    write!(
+        v,
+        r"
+"
+    );
+
+    // Don't warn on CRLF (#4208)
+    write!(v, "\r\n");
+    write!(v, "foo\r\n");
+    write!(v, "\\r\n"); //~ ERROR
+    write!(v, "foo\rbar\n");
+}