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// run-pass
// ignore-wasm32
// ignore-wasm64
#![feature(format_args_capture)]
fn main() {
named_argument_takes_precedence_to_captured();
panic_with_single_argument_does_not_get_formatted();
panic_with_multiple_arguments_is_formatted();
formatting_parameters_can_be_captured();
}
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 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.
let msg = std::panic::catch_unwind(|| {
panic!("{foo}");
}).unwrap_err();
assert_eq!(msg.downcast_ref::<&str>(), Some(&"{foo}"))
}
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::<String>(), 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$}");
assert_eq!(&s, " 7");
let s = format!("{x:<width$}");
assert_eq!(&s, "7 ");
let s = format!("{x:-^width$}");
assert_eq!(&s, "----7----");
let s = format!("{x:-^width$.precision$}");
assert_eq!(&s, "--7.000--");
}
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