See https://github.com/cython/cython/issues/4187

Rewrite the section on fused types in function signatures to make it clearer how multiple fused types interact here.

Refactor function to make it less verbose and simpler to change: error cases first, then special cases, then normal behaviour.

Make code more readable by changing the order of a condition and moving the simple return case first.

For example, if they're called on entry/exit to a decorated function they pick up the directives.
They should really be independent of most user defined settings, especially local ones.

Add --skip-interpreter option to cygdb

* Fix class attributes access where cpp_locals=False.
* Add "no-cpp-locals" tag to mark a test as not suitable for running with "cpp_locals=True".
* Add a list of "extra_directives" to runtests as additional test mode.

Resolves some issues in https://github.com/cython/cython/issues/4266

Seems a remanant of an earlier implementation, but generator expressions *never* use "GeneratorExpressionScope" and in fact it's only used for comprehensions.

Set the "is_target" attribute for names, attributes and temps (anything name-like) to preserve that information for later pipeline steps.

Avoid going through an attribute assignment for an intermediate node result since it may not be the end result.

Closes https://github.com/cython/cython/issues/4268

Closes https://github.com/cython/cython/issues/4268