Add a newline in patched errors

[jcrist]

Adds a blankline between the original error message and the help
message. This makes it easier to read as a user.

Changes

TypingError: `a` must be a NumPy ndarray
This is not usually a problem with Numba itself but instead often caused by
the use of unsupported features or an issue in resolving types.

To see Python/NumPy features supported by the latest release of Numba visit:
http://numba.pydata.org/numba-doc/latest/reference/pysupported.html
and
http://numba.pydata.org/numba-doc/latest/reference/numpysupported.html

For more information about typing errors and how to debug them visit:
http://numba.pydata.org/numba-doc/latest/user/troubleshoot.html#my-code-doesn-t-compile

If you think your code should work with Numba, please report the error message
and traceback, along with a minimal reproducer at:
https://github.com/numba/numba/issues/new

to

TypingError: `a` must be a NumPy ndarray

This is not usually a problem with Numba itself but instead often caused by
the use of unsupported features or an issue in resolving types.

To see Python/NumPy features supported by the latest release of Numba visit:
http://numba.pydata.org/numba-doc/latest/reference/pysupported.html
and
http://numba.pydata.org/numba-doc/latest/reference/numpysupported.html

For more information about typing errors and how to debug them visit:
http://numba.pydata.org/numba-doc/latest/user/troubleshoot.html#my-code-doesn-t-compile

If you think your code should work with Numba, please report the error message
and traceback, along with a minimal reproducer at:
https://github.com/numba/numba/issues/new

[stuartarchibald]

Thanks for the patch. Please could you share the example that was creating this problem in the first place? Locally I have a module of things that cause TypingErrors for the purposes of looking at error message changes and none of them seem to trip it. Thanks.

[jcrist]

This happens if you ever raise a TypingError manually, e.g. in generated_jit. Contrived fake example:

In [1]: import numba as nb

In [2]: @nb.generated_jit
   ...: def int_only_add(a, b):
   ...:     if not (isinstance(a, nb.types.Integer) and isinstance(b, nb.types.Integer)):
   ...:         raise nb.errors.TypingError("Only ints allowed!")
   ...:     return lambda a, b: a + b
   ...:

In [3]: int_only_add(1, 2)
Out[3]: 3

In [4]: int_only_add(1.0, 2.0)
---------------------------------------------------------------------------
TypingError                               Traceback (most recent call last)
<ipython-input-4-7f86f89ddb41> in <module>
----> 1 int_only_add(1.0, 2.0)

~/miniconda3/envs/numba-blis/lib/python3.7/site-packages/numba/dispatcher.py in _compile_for_args(self, *args, **kws)
    374                 e.patch_message(msg)
    375
--> 376             error_rewrite(e, 'typing')
    377         except errors.UnsupportedError as e:
    378             # Something unsupported is present in the user code, add help info

~/miniconda3/envs/numba-blis/lib/python3.7/site-packages/numba/dispatcher.py in error_rewrite(e, issue_type)
    341                 raise e
    342             else:
--> 343                 reraise(type(e), e, None)
    344
    345         argtypes = []

~/miniconda3/envs/numba-blis/lib/python3.7/site-packages/numba/six.py in reraise(tp, value, tb)
    656             value = tp()
    657         if value.__traceback__ is not tb:
--> 658             raise value.with_traceback(tb)
    659         raise value
    660

TypingError: Only ints allowed!
This is not usually a problem with Numba itself but instead often caused by
the use of unsupported features or an issue in resolving types.

To see Python/NumPy features supported by the latest release of Numba visit:
http://numba.pydata.org/numba-doc/latest/reference/pysupported.html
and
http://numba.pydata.org/numba-doc/latest/reference/numpysupported.html

For more information about typing errors and how to debug them visit:
http://numba.pydata.org/numba-doc/latest/user/troubleshoot.html#my-code-doesn-t-compile

If you think your code should work with Numba, please report the error message
and traceback, along with a minimal reproducer at:
https://github.com/numba/numba/issues/new

[stuartarchibald]

Ah, thanks, the extra line is welcomed there!

[stuartarchibald]

Thanks for the patch.