Cython: Tackle some low-hanging fruit in "test_grammar.py"

[scoder]

The latest copy of the CPython grammar tests in test_grammar.py has several @skips and FIXMEs. Some of them seem easy to fix, e.g. some parser bugs or missing warnings that would be helpful, others are entire features. We should fix the easy ones and make sure there are tickets for the rest.

[zdutta]

Attempting to fix use_old_parser(). Trying to use PDB in order to examine the Cython.Compiler.Main.CompilationResult object at 0x7fc06fc49990> created in the compile() method; however, unable to access breakpoints in test_grammar.py when running runtests.py. Any suggestions for debugging?
Thanks!

[da-woods]

If you run runtests.py with --no-capture the debugger should work. --no-fork is probably also a good idea.

[zdutta]

For some reason the breakpoints are still not being stopped at.
Snippet of the commands being run:

[da-woods]

@zdutta Thinking about it more, I think that test_grammar.py is compiled in Cython rather than run as a regular Python module. I wouldn't expect the debugger to work on it.

I think there are some methods to debug Cython code but I've never really tried using them myself (and I especially don't know how to do them with the test-suite). Sorry!

[scoder]

Sorry, the "FIXME" in use_old_parser() is actually a FIXME from CPython (hopefully the only one), not from Cython. The test file is copied from the CPython test suite. Nothing to fix here.

Note that you need to debug Cython itself here, not the test that it compiles.

For debugging, I suggest copying the failing code out of the module and running it through Cython manually, rather than always compiling the huge file completely and trying to end up in the right spot to debug it.

[rh961]

Very good and thank