bazelbuild/bazel · error · OptionsParsingException

Not a valid regular expression: " + e.getMessage()

Error message

Not a valid regular expression: " + e.getMessage()

What it means

Thrown by Converters.RegexPatternConverter.convert when Pattern.compile() rejects the input (after StringEncoding.internalToUnicode unescaping) with a PatternSyntaxException. The converter exists to fail fast at option-parsing time so an invalid regular expression never reaches the code that uses it; the message embeds the underlying Java regex error and position.

Solutions

  1. Fix the regex per the PatternSyntaxException detail in the message (it names the index of the problem).
  2. Escape literal metacharacters: MyTest\.test\[1\].
  3. Test the pattern in isolation first: jshell> Pattern.compile(args[0]).
  4. Mind shell quoting: use single quotes so backslashes survive to Java.

Example fix

# before
bazel test --test_filter='MyTest.test[1]' //...
# after
bazel test --test_filter='MyTest\.test\[1\]' //...
Defensive patterns

Strategy: validation

Validate before calling

boolean isParsableRegex(String s) {
  if (s == null) return false;
  try { Pattern.compile(s, Pattern.DOTALL); return true; }
  catch (PatternSyntaxException e) { return false; }
}

Type guard

boolean isValidRegexFlagValue(String s) {
  if (s == null || s.isEmpty()) return false;
  try { java.util.regex.Pattern.compile(s, java.util.regex.Pattern.DOTALL); return true; }
  catch (java.util.regex.PatternSyntaxException e) { return false; }
}

Try / catch

try {
  RegexPatternOption p = new Converters.RegexPatternConverter().convert(input);
} catch (OptionsParsingException e) {
  // e.getMessage() carries the PatternSyntaxException detail; surface it to the user verbatim
}

Prevention

When it happens

Trigger: Passing --test_filter=Foo( to an option using RegexPatternConverter; unmatched brackets/parens, dangling backslashes, invalid escapes like \y, or malformed repetition like a{2,1}.

Common situations: Method filters with unescaped regex metacharacters (MyTest.test[1]); backslash handling lost through shell quoting; patterns written for a different regex dialect (Perl/POSIX) using unsupported syntax.

Related errors

AI-assisted analysis of bazelbuild/bazel@e6e199d060 (2026-08-14). Data as JSON: /api/errors/74b2c2f8e52fd21e. Report an issue: GitHub.

Appendix: source

Thrown at src/main/java/com/google/devtools/common/options/Converters.java:447

      throw new OptionsParsingException("Not one of " + values);
    }

    @Override
    public String getTypeDescription() {
      return joinEnglishList(values);
    }
  }

  /** Checks whether a string is a valid regex pattern and compiles it. */
  public static class RegexPatternConverter extends Converter.Contextless<RegexPatternOption> {

    @Override
    public RegexPatternOption convert(String input) throws OptionsParsingException {
      try {
        return RegexPatternOption.create(
            Pattern.compile(StringEncoding.internalToUnicode(input), Pattern.DOTALL));
      } catch (PatternSyntaxException e) {
        throw new OptionsParsingException("Not a valid regular expression: " + e.getMessage());
      }
    }

    @Override
    public String getTypeDescription() {
      return "a valid Java regular expression";
    }
  }

  /** Checks whether an integer is in the given range. */
  public static class RangeConverter extends Converter.Contextless<Integer> {
    final int minValue;
    final int maxValue;

    public RangeConverter(int minValue, int maxValue) {
      this.minValue = minValue;
      this.maxValue = maxValue;
    }

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