Merging upstream version 1.71.1+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 21 insertions, 0 deletions

diff --git a/tests/ui/panics/fmt-only-once.rs b/tests/ui/panics/fmt-only-once.rs
new file mode 100644
index 000000000..6211bf961
--- /dev/null
+++ b/tests/ui/panics/fmt-only-once.rs
@@ -0,0 +1,21 @@
+// run-fail
+// check-run-results
+// exec-env:RUST_BACKTRACE=0
+
+// Test that we format the panic message only once.
+// Regression test for https://github.com/rust-lang/rust/issues/110717
+
+use std::fmt;
+
+struct PrintOnFmt;
+
+impl fmt::Display for PrintOnFmt {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        eprintln!("fmt");
+        f.write_str("PrintOnFmt")
+    }
+}
+
+fn main() {
+    panic!("{}", PrintOnFmt)
+}