rust-lang/rust · error · Exception

line {}: {}

Error message

line {}: {}

What it means

Raised by get_commands() in htmldocck when shlex.split() on the args portion of a //@ directive throws an exception other than UnicodeEncodeError. The line number (1-based) and the original exception message are embedded so the offending directive in the rustdoc test template can be located. It is a template-authoring error surfaced while parsing the .rs file.

Source

Thrown at src/etc/htmldocck.py:190

                    line,
                    "Deprecated command syntax, replace `// @` with `//@ `",
                )
                continue
            m = LINE_PATTERN.search(line)
            if not m:
                continue

            cmd = m.group("cmd")
            negated = m.group("negated") == "!"
            args = m.group("args") or ""
            try:
                args = shlex.split(args)
            except UnicodeEncodeError:
                args = [
                    arg.decode("utf-8") for arg in shlex.split(args.encode("utf-8"))
                ]
            except Exception as exc:
                raise Exception("line {}: {}".format(lineno + 1, exc)) from None
            yield Command(
                negated=negated, cmd=cmd, args=args, lineno=lineno + 1, context=line
            )


def _flatten(node, acc):
    if node.text:
        acc.append(node.text)
    for e in node:
        _flatten(e, acc)
        if e.tail:
            acc.append(e.tail)


def flatten(node):
    acc = []
    _flatten(node, acc)
    return "".join(acc)

View on GitHub (pinned to 7088e4b63a)

Solutions

1. Open the .rs test file at the reported line and fix the shell syntax of the directive's arguments (balance quotes, remove stray backslashes).
2. Use shlex-safe quoting: wrap literal values in matching single or double quotes.
3. Re-run the test to confirm the parse error is gone.

Example fix

// before (in the .rs file)
//@ has: '//*[@id="foo"]' "bar"   // line with mismatched/odd quoting

// after
//@ has: //*[@id="foo"] bar

import shlex

def directive_args_parse_ok(args_str: str):
    try:
        shlex.split(args_str)
        return True, None
    except Exception as e:
        return False, str(e)

ok, err = directive_args_parse_ok(args_string_from_template)
if not ok:
    raise SystemExit(f"directive has invalid shlex syntax: {err}")

null

try:
    commands = list(get_commands(template))
except Exception as e:
    if e.args and isinstance(e.args[0], str) and e.args[0].startswith("line "):
        lineno_msg = e.args[0]
        logging.error("htmldocck template syntax error: %s", lineno_msg)
    raise

When it happens

Trigger: A //@ directive line whose args string is not valid shell-lex syntax: unbalanced quotes, a stray backslash, an unclosed substitution, etc. Reached at htmldocck.py:189-190 in the generic `except Exception as exc` branch of shlex.split.

Common situations: Editing a rustdoc UI test and adding a directive with an unbalanced quote (e.g. `//@ has: 'foo"`); copy-pasting a directive that contained shell metacharacters; trailing backslash in the args that confuses shlex.

Related errors

• Non-absolute XPath is not supported due to implementation is
• Tried to use the previous path in the first command
• glob path does not resolve to one file
• File does not exist {!r}
• Cannot parse an HTML file {!r}: {}

AI-assisted analysis of rust-lang/rust@7088e4b63a (2026-08-10). Data as JSON: /api/errors/0971493147d2707e. Report an issue: GitHub.