Summary

Migrate the field and method descriptor parsing from the generic signature parser to the descriptor parser used by java.lang.invoke package.

Problem

The existing generic signature parser is currently in minimal maintenance, and will likely retire when new signature format is introduced.

The generic parser is also unaware of the difference between descriptor strings and generic signatures:

• Ljava/util/Optional<*>; is the class or interface java.util.Optional with a wildcard type argument in generics; it is a class or interface with the simple name Optional<?> in descriptors.
• TT; is a type variable named T in generics; this is not a valid descriptor string.
• L<Stuff>; is not valid in generics; this is a class or interface named <Stuff> in descriptors.

Solution

Migrate to the descriptor parser used by java.lang.invoke, which is widely tested and maintained and largely behaviorally compatible, and is better for dedicated descriptor parsing.

They both throw TypeNotPresentException for valid class or interface names that are not present; the IllegalArgumentException thrown by the descriptor parser can be converted back to a GenericSignatureFormatError as thrown by the existing generic parser.

Specification

None. This is purely behavioral.

There are some significant behavioral changes:

1. Some valid generic signature strings like TT; that caused ClassCastException are now rejected with a GenericSignatureFormatError;
2. Some valid generic signature strings like Ljava/util/Optional<*>; that caused ClassCastException are now accepted but may cause TypeNotPresentException;
3. Some invalid generic signature stirngs like L<Stuff>; that caused GenericSignatureFormatError are now accepted but may cause TypeNotPresentException;
4. Some valid generic signature strings like Ljava/lang/Object<*>; that caused MalformedParameterizedTypeException are now accepted but may cause TypeNotPresentException.