Exhaustiveness of type tuple[bool, bool]
Open
Nobody has claimed this yet.
bug
topic-match-statement
topic-reachability
- Dominant language
- Python
- Stars
- 20.6k
- Forks
- 3.3k
- PR merge metrics
- PR metrics pending
Description
Bug Report
It looks like the exhaustiveness of tuples of bools is not checked in match statements.
To Reproduce
def measure(a: bool, b: bool) -> float:
match a, b:
case True, True:
return 1
case True, False:
return 0.9
case False, True:
return 0.5
case False, False:
return 0
Expected Behavior
Should pass, looks exhaustive to me (or I should go take a nap).
Actual Behavior
$ mypy --enable-error-code exhaustive-match repro.py
repro.py:1: error: Missing return statement [return]
repro.py:2: error: Match statement has unhandled case for values of type "tuple[bool, bool]" [exhaustive-match]
repro.py:2: note: If match statement is intended to be non-exhaustive, add `case _: pass`
Found 2 errors in 1 file (checked 1 source file)
Your Environment
- Mypy version used: mypy 2.3.1 (compiled: yes)
- Mypy command-line flags:
--enable-error-code exhaustive-match - Mypy configuration options from
mypy.ini(and other config files): ø - Python version used: 3.14.7
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.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Run the provided repro with Python 3.14.7 and --enable-error-code exhaustive-match, then trace how exhaustive-match analysis handles tuple[bool, bool] in match statements. Done means the four boolean cases are recognized as exhaustive without a missing-return or unhandled-case error, while genuinely incomplete matches still report errors.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- python
- Domain
- compilers
- Issue type
- Bug
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Activity status
- Active
- Clarity
- Mostly clear
- Newbie friendliness
- 68/100