Fixes for overload_method

[sklam]

Fix #3489. overload_method now supports keyword arguments.
Fix #3683. attribute dispatcher cache will consider the argument types.

[seibert]

Failing on Python 2.7:

2019-01-22T22:03:06.4366190Z ======================================================================
2019-01-22T22:03:06.4366360Z ERROR: test_overload_method_literal_unpack (numba.tests.test_extending.TestHighLevelExtending)
2019-01-22T22:03:06.4367580Z ----------------------------------------------------------------------
2019-01-22T22:03:06.4367670Z Traceback (most recent call last):
2019-01-22T22:03:06.4367720Z   File "numba/tests/test_extending.py", line 899, in test_overload_method_literal_unpack
2019-01-22T22:03:06.4367870Z     bar(A)
2019-01-22T22:03:06.4367930Z   File "numba/dispatcher.py", line 350, in _compile_for_args
2019-01-22T22:03:06.4368430Z     error_rewrite(e, 'typing')
2019-01-22T22:03:06.4368640Z   File "numba/dispatcher.py", line 315, in error_rewrite
2019-01-22T22:03:06.4368700Z     raise e
2019-01-22T22:03:06.4368750Z TypingError: Caused By:
2019-01-22T22:03:06.4368870Z Traceback (most recent call last):
2019-01-22T22:03:06.4368930Z   File "numba/compiler.py", line 243, in run
2019-01-22T22:03:06.4368980Z     stage()
2019-01-22T22:03:06.4369030Z   File "numba/compiler.py", line 482, in stage_nopython_frontend
2019-01-22T22:03:06.4369150Z     self.locals)
2019-01-22T22:03:06.4369200Z   File "numba/compiler.py", line 1025, in type_inference_stage
2019-01-22T22:03:06.4369240Z     infer.propagate()
2019-01-22T22:03:06.4369370Z   File "numba/typeinfer.py", line 858, in propagate
2019-01-22T22:03:06.4369420Z     raise errors[0]
2019-01-22T22:03:06.4370020Z TypingError: Invalid use of BoundFunction((<class 'numba.types.npytypes.Array'>, 'litfoo') for array(float64, 1d, C)) with parameters (Literal[str](LiTeRaL))
2019-01-22T22:03:06.4370190Z  * parameterized
2019-01-22T22:03:06.4370760Z [1] During: resolving callee type: BoundFunction((<class 'numba.types.npytypes.Array'>, 'litfoo') for array(float64, 1d, C))
2019-01-22T22:03:06.4370850Z [2] During: typing of call at numba/tests/test_extending.py (896)
2019-01-22T22:03:06.4370970Z 
2019-01-22T22:03:06.4371010Z 
2019-01-22T22:03:06.4371050Z File "numba/tests/test_extending.py", line 896:
2019-01-22T22:03:06.4371100Z         def bar(A):
2019-01-22T22:03:06.4371220Z             return A.litfoo("LiTeRaL")
2019-01-22T22:03:06.4371270Z             ^
2019-01-22T22:03:06.4371290Z 
2019-01-22T22:03:06.4371320Z 
2019-01-22T22:03:06.4372030Z Invalid use of BoundFunction((<class 'numba.types.npytypes.Array'>, 'litfoo') for array(float64, 1d, C)) with parameters (Literal[str](LiTeRaL))
2019-01-22T22:03:06.4372090Z 
2019-01-22T22:03:06.4372710Z ----------------------------------------------------------------------

[stuartarchibald]

Thanks for the patch. I've tried it out and it seems to fix the problem, it also unblocks #3468. Couple of minor queries to resolve then good for merge.

[stuartarchibald]

Is this branch ever executed?

[sklam]

Yes, kwargs support requires this branch to patch the arguments. When the signature contains Omitted types, those locations are missing in the actual arguments. This re-adds them as required by anything base on Dispatcher.

[stuartarchibald]

hmmm, the added unit tests do not seem to trip this branch, and if I edit the code locally to remove the call to the branch (i.e. revert the change on this line https://github.com/numba/numba/pull/3704/files#diff-d403faa8b837ae083d77e0cba8abd6c7R648) the unit tests for numba.tests.test_extending still pass, can you reproduce this effect? If you can, I'm wondering, practically, how to trip this....?

[sklam]

you're right. It turns out adjusting the pysignature fixes the actual problem already.

[stuartarchibald]

Out of scope so new ticket added... this needs enhancing to also do validation #3708, it was too easy to create invalid overloads when testing this.

[stuartarchibald]

Thanks for the fixes. Looks good. Can be merged once CI passes.