Fix overriding license header bug

[cmichi]

Closes #4487.

[calebcartwright]

LGTM! Would you mind adding a test case to prevent any future regressions?

This would probably be a good place to put it:

rustfmt/src/config.rs

Lines 547 to 562 in cbe01e4

	#[test]
	fn test_empty_string_license_template_path() {
	let toml = r#"license_template_path = """#;
	let config = Config::from_toml(toml, Path::new("")).unwrap();
	assert!(config.license_template.is_none());
	}
	#[test]
	fn test_valid_license_template_path() {
	if !option_env!("CFG_RELEASE_CHANNEL").map_or(true, |c| c == "nightly" || c == "dev") {
	return;
	}
	let toml = r#"license_template_path = "tests/license-template/lt.txt""#;
	let config = Config::from_toml(toml, Path::new("")).unwrap();
	assert!(config.license_template.is_some());
	}

Using a toml config that sets some value (doesn't really matter what) and then overriding the value with an empty string (this is what the cli override uses) and asserting it's none should suffice. Here's two example tests that respectively each do one of those for reference

rustfmt/src/config.rs

Lines 976 to 990 in cbe01e4

	fn test_single_line_if_else_max_width_config_exceeds_max_width() {
	let toml = r#"
	max_width = 70
	single_line_if_else_max_width = 90
	"#;
	let config = Config::from_toml(toml, Path::new("")).unwrap();
	assert_eq!(config.single_line_if_else_max_width(), 70);
	}
	#[test]
	fn test_override_fn_call_width_exceeds_max_width() {
	let mut config = Config::default();
	config.override_value("fn_call_width", "101");
	assert_eq!(config.fn_call_width(), 100);
	}

[calebcartwright]

Sorry I forgot to mention, add this to the test

if !is_nightly_channel!() {
    // This test requires nightly
    return;
}

[cmichi]

@calebcartwright Thanks, I think the failing tests are due to network latency, could you restart them please?

And if you would be so kind, do you have any idea when this will land in a published release?

[calebcartwright]

Thanks!

[calebcartwright]

And if you would be so kind, do you have any idea when this will land in a published release?

Planning to backport this into the upcoming 1.4.23 release, but no date yet on when that'll hit nightly