Vendor dependencies for 0.3.0 release

vendor/thiserror/tests/ui/fallback-impl-with-display.rs

@@ -0,0 +1,14 @@
+use core::fmt::{self, Display};
+use thiserror::Error;
+
+#[derive(Error, Debug)]
+#[error]
+pub struct MyError;
+
+impl Display for MyError {
+    fn fmt(&self, _formatter: &mut fmt::Formatter) -> fmt::Result {
+        unimplemented!()
+    }
+}
+
+fn main() {}