better static checks on initializing CheckedDict variables with dictionary literals
Nobody has claimed this yet.
Assessment
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Newbie friendliness
- 42/100
Research direction
Start with cinder/3.8/Lib/test/test_compiler/test_static/tests.py, especially test_compile_checked_dict_with_annotation_wrong_key_type and the similar wrong-value-type test. Run these tests and trace the static checker behavior for a CheckedDict annotation assigned a dictionary literal; done means key expressions are checked against T1 and values against T2, with the key mismatch reported directly.
Written by the indexing model from the issue text.
Description
a4a71ae
2021-12-20
What program did you run?
from __static__ import CheckedDict
class B: pass
def testfunc():
x: CheckedDict[B, int] = {object():42}
return x
This program is found in cinder/3.8/Lib/test/test_compiler/test_static/tests.py. This test is labeled test_compile_checked_dict_with_annotation_wrong_key_type. There is a similar test labeled test_compile_checked_dict_with_annotation_wrong_value_type.
What happened?
compiler.errors.TypedSyntaxError: type mismatch: Exact[chkdict[object, Literal[42]]] cannot be assigned to Exact[chkdict[__main__.B, int]]
What should have happened?
We expected a compile-time error complaining that object cannot be assigned to B. In general, we expect that everytime the type checker sees x: CheckedDict[T1, T2] = { e1: e2, ... }, it checks every key expression e1 against T1, and every e2 against T2.
- Dominant language
- Python
- Stars
- 3.8k
- Forks
- 139
- PR merge metrics
- No merged PRs in 30d
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
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- Open a pull request that references the issue number.
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