compiletest: Better error message for bad normalize-* headers

src/tools/compiletest/src/header.rs

@@ -991,13 +991,19 @@ impl Config {
  }
 
  fn parse_custom_normalization(&self, line: &str, prefix: &str) -> Option<(String, String)> {
- if parse_cfg_name_directive(self, line, prefix).outcome == MatchOutcome::Match {
- let (regex, replacement) = parse_normalize_rule(line)
- .unwrap_or_else(|| panic!("couldn't parse custom normalization rule: `{line}`"));
- Some((regex, replacement))
- } else {
- None
+ let parsed = parse_cfg_name_directive(self, line, prefix);
+ if parsed.outcome != MatchOutcome::Match {
+ return None;
  }
+ let name = parsed.name.expect("successful match always has a name");
+
+ let Some((regex, replacement)) = parse_normalize_rule(line) else {
+ panic!(
+ "couldn't parse custom normalization rule: `{line}`\n\
+ help: expected syntax is: `{prefix}-{name}: \"REGEX\" -> \"REPLACEMENT\"`"
+ );
+ };
+ Some((regex, replacement))
  }
 
  fn parse_name_directive(&self, line: &str, directive: &str) -> bool {