[PATCH v4 00/19] qapi: static typing conversion, pt3

[John Snow]

Hi, this series adds static types to the QAPI module.
This is part three, and it focuses on expr.py.

Environment:
- Python >= 3.6, <= 3.8 *
- mypy >= 0.770
- pylint >= 2.6.0
- flake8
- isort

Every commit should pass with (from ./scripts/):
 - flake8 qapi/
 - pylint --rcfile=qapi/pylintrc qapi/
 - mypy --config-file=qapi/mypy.ini qapi/
 - pushd qapi && isort -c . && popd

V4:

Patch 2 is exploratory.
Patch 8 is broken and should be merged into Patch 9.
Patches 17-19 are optional and I'd sooner you drop them than have to respin.

001/19:[down] 'qapi/expr: Comment cleanup'
002/19:[down] 'flake8: Enforce shorter line length for comments and docstrings'
003/19:[----] [--] 'qapi/expr.py: Remove 'info' argument from nested 
check_if_str'
004/19:[----] [--] 'qapi/expr.py: Check for dict instead of OrderedDict'
005/19:[0011] [FC] 'qapi/expr.py: constrain incoming expression types'
006/19:[0006] [FC] 'qapi/expr.py: Add assertion for union type 'check_dict''
007/19:[----] [--] 'qapi/expr.py: move string check upwards in check_type'
008/19:[down] 'qapi: add tests for invalid 'data' field type'
009/19:[0004] [FC] 'qapi/expr.py: Check type of 'data' member'
010/19:[0008] [FC] 'qapi/expr.py: Add casts in a few select cases'
011/19:[0005] [FC] 'qapi/expr.py: Modify check_keys to accept any Collection'
012/19:[0057] [FC] 'qapi/expr.py: add type hint annotations'
013/19:[0032] [FC] 'qapi/expr.py: Consolidate check_if_str calls in check_if'
014/19:[0016] [FC] 'qapi/expr.py: Remove single-letter variable'
015/19:[----] [--] 'qapi/expr.py: enable pylint checks'
016/19:[0168] [FC] 'qapi/expr.py: Add docstrings'
017/19:[----] [-C] 'qapi/expr.py: Use tuples instead of lists for static data'
018/19:[----] [-C] 'qapi/expr.py: move related checks inside check_xxx 
functions'
019/19:[0003] [FC] 'qapi/expr.py: Use an expression checker dispatch table'

- Add test patch to demonstrate 72col docstring enforcement. (Not a fan.)
- Changed MutableMapping type to regular ol' dict.
- Added tests for alternate and union to see what happens when we pass a list
  for 'data' instead. (It crashes.)
- Rewrote a bunch of the docstrings.
- Updated type hints for rc0
- Rebased on latest master, incorporating latest qapi changes.
- Addressed most feedback, some exceptions;
  - Kept isinstance check for dict; it is strictly more convenient to me and it
    does not cause breakages. It won't cause breakages.

RFCs/notes:

- I'd be flabbergasted if anyone reads these.

John Snow (19):
  qapi/expr: Comment cleanup
  flake8: Enforce shorter line length for comments and docstrings
  qapi/expr.py: Remove 'info' argument from nested check_if_str
  qapi/expr.py: Check for dict instead of OrderedDict
  qapi/expr.py: constrain incoming expression types
  qapi/expr.py: Add assertion for union type 'check_dict'
  qapi/expr.py: move string check upwards in check_type
  qapi: add tests for invalid 'data' field type
  qapi/expr.py: Check type of 'data' member
  qapi/expr.py: Add casts in a few select cases
  qapi/expr.py: Modify check_keys to accept any Collection
  qapi/expr.py: add type hint annotations
  qapi/expr.py: Consolidate check_if_str calls in check_if
  qapi/expr.py: Remove single-letter variable
  qapi/expr.py: enable pylint checks
  qapi/expr.py: Add docstrings
  qapi/expr.py: Use tuples instead of lists for static data
  qapi/expr.py: move related checks inside check_xxx functions
  qapi/expr.py: Use an expression checker dispatch table

 scripts/qapi/.flake8                          |   1 +
 scripts/qapi/common.py                        |   8 +-
 scripts/qapi/events.py                        |   9 +-
 scripts/qapi/expr.py                          | 499 +++++++++++++-----
 scripts/qapi/gen.py                           |   8 +-
 scripts/qapi/introspect.py                    |   8 +-
 scripts/qapi/main.py                          |   4 +-
 scripts/qapi/mypy.ini                         |   5 -
 scripts/qapi/parser.py                        |  15 +-
 scripts/qapi/pylintrc                         |   1 -
 scripts/qapi/schema.py                        |  23 +-
 scripts/qapi/types.py                         |   7 +-
 .../alternate-invalid-data-type.err           |   2 +
 .../alternate-invalid-data-type.json          |   4 +
 .../alternate-invalid-data-type.out           |   0
 tests/qapi-schema/meson.build                 |   2 +
 tests/qapi-schema/union-invalid-data-type.err |   2 +
 .../qapi-schema/union-invalid-data-type.json  |  13 +
 tests/qapi-schema/union-invalid-data-type.out |   0
 19 files changed, 449 insertions(+), 162 deletions(-)
 create mode 100644 tests/qapi-schema/alternate-invalid-data-type.err
 create mode 100644 tests/qapi-schema/alternate-invalid-data-type.json
 create mode 100644 tests/qapi-schema/alternate-invalid-data-type.out
 create mode 100644 tests/qapi-schema/union-invalid-data-type.err
 create mode 100644 tests/qapi-schema/union-invalid-data-type.json
 create mode 100644 tests/qapi-schema/union-invalid-data-type.out

-- 
2.30.2