Fix #6069

src/items.rs

@@ -1166,9 +1166,9 @@ pub(crate) fn format_trait(
 
  // FIXME(#2055): rustfmt fails to format when there are comments between trait bounds.
  if !bounds.is_empty() {
- let ident_hi = context
-  .snippet_provider
-  .span_after(item.span, item.ident.as_str());
+ // Retrieve *unnormalized* ident (See #6069)
+ let source_ident = context.snippet(item.ident.span);
+ let ident_hi = context.snippet_provider.span_after(item.span, source_ident);
  let bound_hi = bounds.last().unwrap().span().hi();
  let snippet = context.snippet(mk_sp(ident_hi, bound_hi));
  if contains_comment(snippet) {

tests/rustfmt/main.rs

@@ -176,7 +176,7 @@ fn rustfmt_emits_error_on_line_overflow_true() {
 #[test]
 #[allow(non_snake_case)]
 fn dont_emit_ICE() {
- let files = ["tests/target/issue_5728.rs", "tests/target/issue_5729.rs"];
+ let files = ["tests/target/issue_5728.rs", "tests/target/issue_5729.rs", "tests/target/issue_6069.rs"];
 
  for file in files {
  let args = [file];

tests/target/issue_6069.rs

@@ -0,0 +1,3 @@
+// `Foó` as written here ends with ASCII 6F `'o'` followed by `'\u{0301}'` COMBINING ACUTE ACCENT.
+// The compiler normalizes that combination to NFC form, `'\u{00F3}'` LATIN SMALL LETTER O WITH ACUTE.
+trait Foó: Bar {}