Class IterationErrorWatcher

mypy/errors.py:391–433

Error watcher that filters and separately collects `unreachable` errors, `redundant-expr` and `redundant-casts` errors, and revealed types and non-overlapping types when analysing code sections iteratively to help avoid making too-hasty reports.

class IterationErrorWatcher(ErrorWatcher):
    """Error watcher that filters and separately collects `unreachable` errors,
    `redundant-expr` and `redundant-casts` errors, and revealed types and
    non-overlapping types when analysing code sections iteratively to help avoid
    making too-hasty reports."""

    iteration_dependent_errors: IterationDependentErrors

    def __init__(
        self,
        errors: Errors,
        iteration_dependent_errors: IterationDependentErrors,
        *,
        filter_errors: bool | Callable[[str, ErrorInfo], bool] = False,
        save_filtered_errors: bool = False,
        filter_deprecated: bool = False,
    ) -> None:
        super().__init__(
            errors,
            filter_errors=filter_errors,
            save_filtered_errors=save_filtered_errors,
            filter_deprecated=filter_deprecated,
        )
        self.iteration_dependent_errors = iteration_dependent_errors
        iteration_dependent_errors.uselessness_errors.append(set())
        iteration_dependent_errors.nonoverlapping_types.append({})
        iteration_dependent_errors.unreachable_lines.append(set())

    def on_error(self, file: str, info: ErrorInfo) -> bool:
        """Filter out the "iteration-dependent" errors and notes and store their
        information to handle them after iteration is completed."""

        iter_errors = self.iteration_dependent_errors

        if info.code in (codes.UNREACHABLE, codes.REDUNDANT_EXPR, codes.REDUNDANT_CAST):
            iter_errors.uselessness_errors[-1].add(
                (info.code, info.message, info.line, info.column, info.end_line, info.end_column)
            )
            if info.code == codes.UNREACHABLE:
                iter_errors.unreachable_lines[-1].update(range(info.line, info.end_line + 1))
            return True

        return super().on_error(file, info)


class Errors: