Add test of Display impl nested inside display attribute
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@ -1,4 +1,4 @@
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use std::fmt::Display;
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use std::fmt::{self, Display};
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use thiserror::Error;
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fn assert<T: Display>(expected: &str, value: T) {
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@ -141,6 +141,35 @@ fn test_match() {
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);
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}
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#[test]
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fn test_nested_display() {
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// Same behavior as the one in `test_match`, but without String allocations.
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#[derive(Error, Debug)]
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#[error("{}", {
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struct Msg<'a>(&'a String, &'a Option<usize>);
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impl<'a> Display for Msg<'a> {
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fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
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match self.1 {
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Some(n) => write!(formatter, "error occurred with {}", n),
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None => write!(formatter, "there was an empty error"),
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}?;
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write!(formatter, ": {}", self.0)
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}
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}
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Msg(.0, .1)
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})]
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struct Error(String, Option<usize>);
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assert(
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"error occurred with 1: ...",
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Error("...".to_owned(), Some(1)),
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);
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assert(
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"there was an empty error: ...",
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Error("...".to_owned(), None),
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);
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}
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#[test]
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fn test_void() {
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#[allow(clippy::empty_enum)]
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