Followup changes to fix ruff & pyright warnings (#203)

* Annotate error_codes with Mapping instead of dict to silence warnings about mutable classvar, Write __hash__ for Statement

flake8_trio/base.py

@@ -29,18 +29,22 @@ class Statement(NamedTuple):
     lineno: int
     col_offset: int = -1
 
-    # pyright is unhappy about defining __eq__ but not __hash__ .. which it should
-    # but it works :tm: and needs changing in a couple places to avoid it.
     def __eq__(self, other: object) -> bool:
         return (
             isinstance(other, Statement)
-            and self[:2] == other[:2]
+            and self.name == other.name
+            and self.lineno == other.lineno
             and (
                 self.col_offset == other.col_offset
                 or -1 in (self.col_offset, other.col_offset)
             )
         )
 
+    # Objects that are equal needs to have the same hash, so we don't hash on
+    # `col_offset` since it's a "wildcard" value
+    def __hash__(self) -> int:
+        return hash((self.name, self.lineno))
+
 
 class Error:
     def __init__(

flake8_trio/runner.py

@@ -21,7 +21,7 @@
 from .visitors.visitor_utility import NoqaHandler
 
 if TYPE_CHECKING:
-    from collections.abc import Iterable
+    from collections.abc import Iterable, Mapping
 
     from libcst import Module
 
@@ -46,7 +46,7 @@ def __init__(self, options: Options):
         super().__init__()
         self.state = SharedState(options)
 
-    def selected(self, error_codes: dict[str, str]) -> bool:
+    def selected(self, error_codes: Mapping[str, str]) -> bool:
         enabled_or_autofix = (
             self.state.options.enabled_codes | self.state.options.autofix_codes
         )

flake8_trio/visitors/flake8triovisitor.py

@@ -4,15 +4,15 @@
 
 import ast
 from abc import ABC
-from typing import TYPE_CHECKING, Any, ClassVar, Union
+from typing import TYPE_CHECKING, Any, Union
 
 import libcst as cst
 from libcst.metadata import PositionProvider
 
 from ..base import Error, Statement
 
 if TYPE_CHECKING:
-    from collections.abc import Iterable
+    from collections.abc import Iterable, Mapping
 
     from ..runner import SharedState
 
@@ -23,7 +23,7 @@
 
 class Flake8TrioVisitor(ast.NodeVisitor, ABC):
     # abstract attribute by not providing a value
-    error_codes: ClassVar[dict[str, str]]
+    error_codes: Mapping[str, str]
 
     def __init__(self, shared_state: SharedState):
         super().__init__()
@@ -158,7 +158,7 @@ def add_library(self, name: str) -> None:
 
 class Flake8TrioVisitor_cst(cst.CSTTransformer, ABC):
     # abstract attribute by not providing a value
-    error_codes: dict[str, str]
+    error_codes: Mapping[str, str]
     METADATA_DEPENDENCIES = (PositionProvider,)
 
     def __init__(self, shared_state: SharedState):

flake8_trio/visitors/visitor100.py

@@ -8,7 +8,7 @@
 
 from __future__ import annotations
 
-from typing import Any
+from typing import TYPE_CHECKING, Any
 
 import libcst as cst
 import libcst.matchers as m
@@ -21,10 +21,13 @@
     with_has_call,
 )
 
+if TYPE_CHECKING:
+    from collections.abc import Mapping
+
 
 @error_class_cst
 class Visitor100_libcst(Flake8TrioVisitor_cst):
-    error_codes = {
+    error_codes: Mapping[str, str] = {
         "TRIO100": (
             "{0}.{1} context contains no checkpoints, remove the context or add"
             " `await {0}.lowlevel.checkpoint()`."

flake8_trio/visitors/visitor101.py

@@ -17,12 +17,14 @@
 )
 
 if TYPE_CHECKING:
+    from collections.abc import Mapping
+
     import libcst as cst
 
 
 @error_class_cst
 class Visitor101(Flake8TrioVisitor_cst):
-    error_codes = {
+    error_codes: Mapping[str, str] = {
         "TRIO101": (
             "`yield` inside a nursery or cancel scope is only safe when implementing "
             "a context manager - otherwise, it breaks exception handling."

flake8_trio/visitors/visitor102.py

@@ -6,16 +6,19 @@
 from __future__ import annotations
 
 import ast
-from typing import Any
+from typing import TYPE_CHECKING, Any
 
 from ..base import Statement
 from .flake8triovisitor import Flake8TrioVisitor
 from .helpers import cancel_scope_names, critical_except, error_class, get_matching_call
 
+if TYPE_CHECKING:
+    from collections.abc import Mapping
+
 
 @error_class
 class Visitor102(Flake8TrioVisitor):
-    error_codes = {
+    error_codes: Mapping[str, str] = {
         "TRIO102": (
             "await inside {0.name} on line {0.lineno} must have shielded cancel "
             "scope with a timeout."

flake8_trio/visitors/visitor103_104.py

@@ -9,11 +9,14 @@
 from __future__ import annotations
 
 import ast
-from typing import Any
+from typing import TYPE_CHECKING, Any
 
 from .flake8triovisitor import Flake8TrioVisitor
 from .helpers import critical_except, error_class, iter_guaranteed_once
 
+if TYPE_CHECKING:
+    from collections.abc import Mapping
+
 _trio103_common_msg = "{} block with a code path that doesn't re-raise the error."
 _suggestion = " Consider adding an `except {}: raise` before this exception handler."
 _suggestion_dict: dict[tuple[str, ...], str] = {
@@ -22,17 +25,19 @@
 }
 _suggestion_dict[("anyio", "trio")] = "[" + "|".join(_suggestion_dict.values()) + "]"
 
+_error_codes = {
+    "TRIO103": _trio103_common_msg,
+    "TRIO104": "Cancelled (and therefore BaseException) must be re-raised.",
+}
+for poss_library in _suggestion_dict:
+    _error_codes[f"TRIO103_{'_'.join(poss_library)}"] = (
+        _trio103_common_msg + _suggestion.format(_suggestion_dict[poss_library])
+    )
+
 
 @error_class
 class Visitor103_104(Flake8TrioVisitor):
-    error_codes = {
-        "TRIO103": _trio103_common_msg,
-        "TRIO104": "Cancelled (and therefore BaseException) must be re-raised.",
-    }
-    for poss_library in _suggestion_dict:
-        error_codes[f"TRIO103_{'_'.join(poss_library)}"] = (
-            _trio103_common_msg + _suggestion.format(_suggestion_dict[poss_library])
-        )
+    error_codes: Mapping[str, str] = _error_codes
 
     def __init__(self, *args: Any, **kwargs: Any):
         super().__init__(*args, **kwargs)

flake8_trio/visitors/visitor105.py

@@ -3,11 +3,15 @@
 from __future__ import annotations
 
 import ast
-from typing import Any
+from typing import TYPE_CHECKING, Any
 
 from .flake8triovisitor import Flake8TrioVisitor
 from .helpers import error_class
 
+if TYPE_CHECKING:
+    from collections.abc import Mapping
+
+
 # used in 105
 trio_async_funcs = (
     "trio.aclose_forcefully",
@@ -39,7 +43,7 @@
 
 @error_class
 class Visitor105(Flake8TrioVisitor):
-    error_codes = {
+    error_codes: Mapping[str, str] = {
         "TRIO105": "{0} async {1} must be immediately awaited.",
     }
 

flake8_trio/visitors/visitor111.py

@@ -3,15 +3,18 @@
 from __future__ import annotations
 
 import ast
-from typing import Any, NamedTuple
+from typing import TYPE_CHECKING, Any, NamedTuple
 
 from .flake8triovisitor import Flake8TrioVisitor
 from .helpers import error_class, get_matching_call
 
+if TYPE_CHECKING:
+    from collections.abc import Mapping
+
 
 @error_class
 class Visitor111(Flake8TrioVisitor):
-    error_codes = {
+    error_codes: Mapping[str, str] = {
         "TRIO111": (
             "variable {2} is usable within the context manager on line {0}, but that "
             "will close before nursery opened on line {1} - this is usually a bug.  "

flake8_trio/visitors/visitor118.py

@@ -8,14 +8,18 @@
 
 import ast
 import re
+from typing import TYPE_CHECKING
 
 from .flake8triovisitor import Flake8TrioVisitor
 from .helpers import error_class
 
+if TYPE_CHECKING:
+    from collections.abc import Mapping
+
 
 @error_class
 class Visitor118(Flake8TrioVisitor):
-    error_codes = {
+    error_codes: Mapping[str, str] = {
         "TRIO118": (
             "Don't assign the value of `anyio.get_cancelled_exc_class()` to a variable,"
             " since that breaks linter checks and multi-backend programs."

flake8_trio/visitors/visitor2xx.py

@@ -12,15 +12,18 @@
 
 import ast
 import re
-from typing import Any
+from typing import TYPE_CHECKING, Any
 
 from .flake8triovisitor import Flake8TrioVisitor
 from .helpers import error_class, fnmatch_qualified_name, get_matching_call
 
+if TYPE_CHECKING:
+    from collections.abc import Mapping
+
 
 @error_class
 class Visitor200(Flake8TrioVisitor):
-    error_codes = {
+    error_codes: Mapping[str, str] = {
         "TRIO200": (
             "User-configured blocking sync call {0} in async function, consider "
             "replacing with {1}."
@@ -55,7 +58,7 @@ def visit_blocking_call(self, node: ast.Call):
 
 @error_class
 class Visitor21X(Visitor200):
-    error_codes = {
+    error_codes: Mapping[str, str] = {
         "TRIO210": "Sync HTTP call {} in async function, use `httpx.AsyncClient`.",
         "TRIO211": (
             "Likely sync HTTP call {} in async function, use `httpx.AsyncClient`."
@@ -114,7 +117,7 @@ def visit_blocking_call(self, node: ast.Call):
 
 @error_class
 class Visitor212(Visitor200):
-    error_codes = {
+    error_codes: Mapping[str, str] = {
         "TRIO212": (
             "Blocking sync HTTP call {1} on httpx object {0}, use httpx.AsyncClient."
         )
@@ -166,7 +169,7 @@ def visit_blocking_call(self, node: ast.Call):
 # Process invocations 202
 @error_class
 class Visitor22X(Visitor200):
-    error_codes = {
+    error_codes: Mapping[str, str] = {
         "TRIO220": (
             "Sync call {} in async function, use "
             "`await nursery.start({}.run_process, ...)`."
@@ -225,7 +228,7 @@ def is_p_wait(arg: ast.expr) -> bool:
 
 @error_class
 class Visitor23X(Visitor200):
-    error_codes = {
+    error_codes: Mapping[str, str] = {
         "TRIO230": "Sync call {0} in async function, use `{1}.open_file(...)`.",
         "TRIO231": "Sync call {0} in async function, use `{1}.wrap_file({0})`.",
     }
@@ -251,7 +254,7 @@ def visit_blocking_call(self, node: ast.Call):
 
 @error_class
 class Visitor232(Visitor200):
-    error_codes = {
+    error_codes: Mapping[str, str] = {
         "TRIO232": (
             "Blocking sync call {1} on file object {0}, wrap the file object"
             "in `{2}.wrap_file()` to get an async file object."
@@ -281,7 +284,7 @@ def visit_blocking_call(self, node: ast.Call):
 
 @error_class
 class Visitor24X(Visitor200):
-    error_codes = {
+    error_codes: Mapping[str, str] = {
         "TRIO240": "Avoid using os.path, prefer using {1}.Path objects.",
     }
 

flake8_trio/visitors/visitor91x.py

@@ -26,9 +26,10 @@
 )
 
 if TYPE_CHECKING:
-    from collections.abc import Sequence
+    from collections.abc import Mapping, Sequence
 
 
+# Statement injected at the start of loops to track missed checkpoints.
 ARTIFICIAL_STATEMENT = Statement("artificial", -1)
 
 
@@ -226,7 +227,7 @@ def leave_Yield(
 @error_class_cst
 @disabled_by_default
 class Visitor91X(Flake8TrioVisitor_cst, CommonVisitors):
-    error_codes = {
+    error_codes: Mapping[str, str] = {
         "TRIO910": (
             "{0} from async function with no guaranteed checkpoint or exception "
             "since function definition on line {1.lineno}."
@@ -591,10 +592,7 @@ def visit_While_body(self, node: cst.For | cst.While):
         if getattr(node, "asynchronous", None):
             self.uncheckpointed_statements = set()
         else:
-            # pyright correctly dislikes Statement defining __eq__ but not __hash__
-            # but it works:tm:, and changing it touches on various bits of code, so
-            # leaving it for another time.
-            self.uncheckpointed_statements = {ARTIFICIAL_STATEMENT}  # pyright: ignore
+            self.uncheckpointed_statements = {ARTIFICIAL_STATEMENT}
 
         self.loop_state.uncheckpointed_before_continue = set()
         self.loop_state.uncheckpointed_before_break = set()