--- /dev/null
+// run-rustfix
+#![allow(unused_imports)]
+#![warn(clippy::explicit_write)]
+
+fn stdout() -> String {
+ String::new()
+}
+
+fn stderr() -> String {
+ String::new()
+}
+
+fn main() {
+ // these should warn
+ {
+ use std::io::Write;
+ write!(std::io::stdout(), "test").unwrap();
+ write!(std::io::stderr(), "test").unwrap();
+ writeln!(std::io::stdout(), "test").unwrap();
+ writeln!(std::io::stderr(), "test").unwrap();
+ std::io::stdout().write_fmt(format_args!("test")).unwrap();
+ std::io::stderr().write_fmt(format_args!("test")).unwrap();
+
+ // including newlines
+ writeln!(std::io::stdout(), "test\ntest").unwrap();
+ writeln!(std::io::stderr(), "test\ntest").unwrap();
+ }
+ // these should not warn, different destination
+ {
+ use std::fmt::Write;
+ let mut s = String::new();
+ write!(s, "test").unwrap();
+ write!(s, "test").unwrap();
+ writeln!(s, "test").unwrap();
+ writeln!(s, "test").unwrap();
+ s.write_fmt(format_args!("test")).unwrap();
+ s.write_fmt(format_args!("test")).unwrap();
+ write!(stdout(), "test").unwrap();
+ write!(stderr(), "test").unwrap();
+ writeln!(stdout(), "test").unwrap();
+ writeln!(stderr(), "test").unwrap();
+ stdout().write_fmt(format_args!("test")).unwrap();
+ stderr().write_fmt(format_args!("test")).unwrap();
+ }
+ // these should not warn, no unwrap
+ {
+ use std::io::Write;
+ std::io::stdout().write_fmt(format_args!("test")).expect("no stdout");
+ std::io::stderr().write_fmt(format_args!("test")).expect("no stderr");
+ }
+}