Bug 255640

Description Stephan Herrmann 2008-11-18 08:50:36 EST

Build ID: M20080911-1700

Looking at the javadocs it is not clear how the toCharArray family of
methods in org.eclipse.jdt.core.Signature handles empty char[] as input.
The docs only say:
  @exception IllegalArgumentException if the signature is not syntactically correct
One could argue that an empty string cannot contain syntax errors.

Digging into the implementation one hint is found in appendTypeSignature:
  // need a minimum 1 char

The following snippet from toCharArray(char[]) looks confusing to me:
  int sigLength = signature.length;
  if (sigLength == 0 || signature[0] == C_PARAM_START || signature[0] == C_GENERIC_START) {
    return toCharArray(signature, CharOperation.NO_CHAR, null, true, true);
  }

Note, that the second toCharArray-method is intended for parsing
method signatures only and it fails with an IllegalArgumentException
if no C_PARAM_START is found within the input. For length 0 this
will invariable happen. Without changing the behavior
the same could be achieved (in a less confusing way) by:
  int sigLength = signature.length;
  if (sigLength == 0)
    throw new IllegalArgumentException();
  if (signature[0] == C_PARAM_START || signature[0] == C_GENERIC_START) {
    return toCharArray(signature, CharOperation.NO_CHAR, null, true, true);
  }
If that's indeed the intended behavior I'd suggest to add to the docs that
the input must not be an empty string/char[].