Fix crash indenting quoted suffix after command substitution

Commit b00899179 (Don't indent multi-line quoted strings; do indent inside
(), 2024-04-28) made parse_util_compute_indents() crash on `echo "$()"'x`.
After recursively indenting the command substitution, we indent the "'x
suffix.  We skip the quoted part by setting "done=2".  Later we wrongly
index "self.indents[done..range.start+offset+1]" (= "self.indents[2..1]").

Fix this by making sure that "start >= done", thus not setting any indents
for the quoted suffix.  There is no need to do so; only the first character
in each line needs an indent.

src/parse_util.rs

@@ -941,42 +941,38 @@ impl<'a> IndentVisitor<'a> {
     }
 
     fn indent_string_part(&mut self, range: Range<usize>, is_double_quoted: bool) {
-        let mut done = range.start;
+        let mut start = range.start;
         let mut quoted = false;
-        {
         if is_double_quoted {
             match quote_end(self.src, range.start, '"') {
                 Some(q_end) => {
                     // We may be (in) a multi-line string, so don't indent.
-                        done = q_end + 1;
+                    start = q_end + 1;
                 }
                 None => quoted = true,
             }
         }
-            let part = &self.src[done..range.end];
+        let mut done = start;
         if !quoted {
+            let part = &self.src[done..range.end];
             let mut callback = |offset| {
                 if !quoted {
                     // Quote open event. Indent unquoted part, including the opening quote.
-                        self.indents[done..range.start + offset + 1].fill(self.indent);
+                    self.indents[done..start + offset + 1].fill(self.indent);
-                        done = range.start + offset + 1;
+                    done = start + offset + 1;
                 } else {
                     // Quote close. Don't indent, in case it's a multiline string.
                     // Mark the first line as indented but only to make tests look prettier.
-                        let first_line_length = self.src[range.start..range.start + offset]
+                    let first_line_length = self.src[start..start + offset]
                         .chars()
                         .take_while(|&c| c != '\n')
                         .count();
-                        self.indents[range.start..range.start + first_line_length]
+                    self.indents[start..start + first_line_length].fill(self.indent);
-                            .fill(self.indent);
+                    done = start + offset;
-                        done = range.start + offset;
                 }
                 quoted = !quoted;
             };
-                for _token in
+            for _token in Tokenizer::with_quote_events(part, TOK_ACCEPT_UNFINISHED, &mut callback) {
-                    Tokenizer::with_quote_events(part, TOK_ACCEPT_UNFINISHED, &mut callback)
-                {
-                }
             }
         }
         if !quoted {

src/tests/parse_util.rs

@@ -435,5 +435,9 @@ fn test_indents() {
             0, "\n) line4",
             0, "\nline5\"",
         );
+        validate!(
+            0, r#"echo "$()"'"#,
+            0, "\n"
+        );
     })();
 }