Method visit_try_stmt

mypy/partially_defined.py:532–562

Note that finding undefined vars in `finally` requires different handling from the rest of the code. In particular, we want to disallow skipping branches due to jump statements in except/else clauses for finally but not for other cases. Imagine a case like: def f() -

(self, o: TryStmt)

        super().visit_expression_stmt(o)

    def visit_try_stmt(self, o: TryStmt) -> None:
        """
        Note that finding undefined vars in `finally` requires different handling from
        the rest of the code. In particular, we want to disallow skipping branches due to jump
        statements in except/else clauses for finally but not for other cases. Imagine a case like:
        def f() -> int:
            try:
                x = 1
            except:
                # This jump statement needs to be handled differently depending on whether or
                # not we're trying to process `finally` or not.
                return 0
            finally:
                # `x` may be undefined here.
                pass
            # `x` is always defined here.
            return x
        """
        self.try_depth += 1
        if o.finally_body is not None:
            # In order to find undefined vars in `finally`, we need to
            # process try/except with branch skipping disabled. However, for the rest of the code
            # after finally, we need to process try/except with branch skipping enabled.
            # Therefore, we need to process try/finally twice.
            # Because processing is not idempotent, we should make a copy of the tracker.
            old_tracker = self.tracker.copy()
            self.tracker.disable_branch_skip = True
            self.process_try_stmt(o)
            self.tracker = old_tracker
        self.process_try_stmt(o)
        self.try_depth -= 1

    def process_try_stmt(self, o: TryStmt) -> None:
        """