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-rw-r--r--tests/ui/fmt/format-args-capture.rs89
1 files changed, 89 insertions, 0 deletions
diff --git a/tests/ui/fmt/format-args-capture.rs b/tests/ui/fmt/format-args-capture.rs
new file mode 100644
index 000000000..560352b5c
--- /dev/null
+++ b/tests/ui/fmt/format-args-capture.rs
@@ -0,0 +1,89 @@
+// 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::<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--");
+}
+
+fn repeated_capture() {
+ let a = 1;
+ let b = 2;
+ let s = format!("{a} {b} {a}");
+ assert_eq!(&s, "1 2 1");
+}