// run-pass fn main() { named_argument_takes_precedence_to_captured(); formatting_parameters_can_be_captured(); capture_raw_strings_and_idents(); repeated_capture(); #[cfg(panic = "unwind")] { panic_with_single_argument_does_not_get_formatted(); panic_with_multiple_arguments_is_formatted(); } } fn named_argument_takes_precedence_to_captured() { let foo = "captured"; let s = format!("{foo}", foo = "named"); assert_eq!(&s, "named"); let s = format!("{foo}-{foo}-{foo}", foo = "named"); assert_eq!(&s, "named-named-named"); let s = format!("{}-{bar}-{foo}", "positional", bar = "named"); assert_eq!(&s, "positional-named-captured"); } fn capture_raw_strings_and_idents() { let r#type = "apple"; let s = format!(r#"The fruit is an {type}"#); assert_eq!(&s, "The fruit is an apple"); let r#type = "orange"; let s = format!(r"The fruit is an {type}"); assert_eq!(&s, "The fruit is an orange"); } #[cfg(panic = "unwind")] fn panic_with_single_argument_does_not_get_formatted() { // panic! with a single argument does not perform string formatting. // RFC #2795 suggests that this may need to change so that captured arguments are formatted. // For stability reasons this will need to part of an edition change. #[allow(non_fmt_panics)] let msg = std::panic::catch_unwind(|| { panic!("{foo}"); }) .unwrap_err(); assert_eq!(msg.downcast_ref::<&str>(), Some(&"{foo}")) } #[cfg(panic = "unwind")] fn panic_with_multiple_arguments_is_formatted() { let foo = "captured"; let msg = std::panic::catch_unwind(|| { panic!("{}-{bar}-{foo}", "positional", bar = "named"); }) .unwrap_err(); assert_eq!(msg.downcast_ref::(), Some(&"positional-named-captured".to_string())) } fn formatting_parameters_can_be_captured() { let width = 9; let precision = 3; let x = 7.0; let s = format!("{x:width$}"); assert_eq!(&s, " 7"); let s = format!("{x: