//@run-rustfix #![warn(clippy::useless_format)] #![allow( unused_tuple_struct_fields, clippy::print_literal, clippy::redundant_clone, clippy::to_string_in_format_args, clippy::needless_borrow, clippy::uninlined_format_args, clippy::useless_vec )] struct Foo(pub String); macro_rules! foo { ($($t:tt)*) => (Foo(format!($($t)*))) } fn main() { format!("foo"); format!("{{}}"); format!("{{}} abc {{}}"); format!( r##"foo {{}} " bar"## ); let _ = format!(""); format!("{}", "foo"); format!("{:?}", "foo"); // Don't warn about `Debug`. format!("{:8}", "foo"); format!("{:width$}", "foo", width = 8); format!("foo {}", "bar"); format!("{} bar", "foo"); let arg = String::new(); format!("{}", arg); format!("{:?}", arg); // Don't warn about debug. format!("{:8}", arg); format!("{:width$}", arg, width = 8); format!("foo {}", arg); format!("{} bar", arg); // We don’t want to warn for non-string args; see issue #697. format!("{}", 42); format!("{:?}", 42); format!("{:+}", 42); format!("foo {}", 42); format!("{} bar", 42); // We only want to warn about `format!` itself. println!("foo"); println!("{}", "foo"); 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()); // False positive let a = "foo".to_string(); let _ = Some(format!("{}", a + "bar")); // Wrap it with braces let v: Vec<String> = vec!["foo".to_string(), "bar".to_string()]; let _s: String = format!("{}", &*v.join("\n")); format!("prepend {:+}", "s"); // Issue #8290 let x = "foo"; let _ = format!("{x}"); let _ = format!("{x:?}"); // Don't lint on debug let _ = format!("{y}", y = x); // Issue #9234 let abc = "abc"; let _ = format!("{abc}"); let xx = "xx"; let _ = format!("{xx}"); }