+// run-rustfix
+#![allow(clippy::print_literal)]
+#![warn(clippy::useless_format)]
-#![warn(useless_format)]
+struct Foo(pub String);
+
+macro_rules! foo {
+ ($($t:tt)*) => (Foo(format!($($t)*)))
+}
fn main() {
format!("foo");
format!("{}", "foo");
- format!("{:?}", "foo"); // we only want to warn about `{}`
- format!("{:+}", "foo"); // we only want to warn about `{}`
+ format!("{:?}", "foo"); // don't warn about debug
+ format!("{:8}", "foo");
+ format!("{:width$}", "foo", width = 8);
+ format!("{:+}", "foo"); // warn when the format makes no difference
+ format!("{:<}", "foo"); // warn when the format makes no difference
format!("foo {}", "bar");
format!("{} bar", "foo");
let arg: String = "".to_owned();
format!("{}", arg);
- format!("{:?}", arg); // we only want to warn about `{}`
- format!("{:+}", arg); // we only want to warn about `{}`
+ format!("{:?}", arg); // don't warn about debug
+ format!("{:8}", arg);
+ format!("{:width$}", arg, width = 8);
+ format!("{:+}", arg); // warn when the format makes no difference
+ format!("{:<}", arg); // warn when the format makes no difference
format!("foo {}", arg);
format!("{} bar", arg);
println!("foo {}", "foo");
println!("{}", 42);
println!("foo {}", 42);
+
+ // A format! inside a macro should not trigger a warning
+ foo!("should not warn");
+
+ // precision on string means slicing without panicking on size:
+ format!("{:.1}", "foo"); // could be "foo"[..1]
+ format!("{:.10}", "foo"); // could not be "foo"[..10]
+ format!("{:.prec$}", "foo", prec = 1);
+ format!("{:.prec$}", "foo", prec = 10);
+
+ format!("{}", 42.to_string());
+ let x = std::path::PathBuf::from("/bar/foo/qux");
+ format!("{}", x.display().to_string());
}