gh-108455: peg_generator: make the mypy config slightly stricter (#108627)

* Enable `--no-implicit-reexport`

* Enable the `truthy-bool` error code

* Enable the `ignore-without-code` error code

* Explicitly note that `--warn-unreachable` cannot yet be enabled

Author: AlexWaygood

Tools/peg_generator/mypy.ini

@@ -8,10 +8,11 @@ python_version = 3.10
 
 # Be strict...
 strict = True
+enable_error_code = truthy-bool,ignore-without-code
 
 # except for a few settings that can't yet be enabled:
 warn_return_any = False
-no_implicit_reexport = False
+warn_unreachable = False
 
 [mypy-pegen.grammar_parser]
 strict_optional = False

Tools/peg_generator/pegen/__main__.py

@@ -12,7 +12,10 @@
 import traceback
 from typing import Tuple
 
-from pegen.build import Grammar, Parser, ParserGenerator, Tokenizer
+from pegen.grammar import Grammar
+from pegen.parser import Parser
+from pegen.parser_generator import ParserGenerator
+from pegen.tokenizer import Tokenizer
 from pegen.validator import validate_grammar
 
 

Tools/peg_generator/pegen/parser.py

@@ -32,7 +32,7 @@ def logger_wrapper(self: "Parser", *args: object) -> Any:
         print(f"{fill}... {method_name}({argsr}) --> {tree!s:.200}")
         return tree
 
-    logger_wrapper.__wrapped__ = method  # type: ignore
+    logger_wrapper.__wrapped__ = method  # type: ignore[attr-defined]
     return cast(F, logger_wrapper)
 
 
@@ -69,7 +69,7 @@ def memoize_wrapper(self: "Parser", *args: object) -> Any:
             self._reset(endmark)
         return tree
 
-    memoize_wrapper.__wrapped__ = method  # type: ignore
+    memoize_wrapper.__wrapped__ = method  # type: ignore[attr-defined]
     return cast(F, memoize_wrapper)
 
 
@@ -153,7 +153,7 @@ def memoize_left_rec_wrapper(self: "Parser") -> Optional[T]:
                 self._reset(endmark)
         return tree
 
-    memoize_left_rec_wrapper.__wrapped__ = method  # type: ignore
+    memoize_left_rec_wrapper.__wrapped__ = method  # type: ignore[attr-defined]
     return memoize_left_rec_wrapper
 
 

Tools/peg_generator/pegen/testutil.py

@@ -37,7 +37,7 @@ def generate_parser(grammar: Grammar) -> Type[Parser]:
 
 def run_parser(file: IO[bytes], parser_class: Type[Parser], *, verbose: bool = False) -> Any:
     # Run a parser on a file (stream).
-    tokenizer = Tokenizer(tokenize.generate_tokens(file.readline))  # type: ignore # typeshed issue #3515
+    tokenizer = Tokenizer(tokenize.generate_tokens(file.readline))  # type: ignore[arg-type] # typeshed issue #3515
     parser = parser_class(tokenizer, verbose=verbose)
     result = parser.start()
     if result is None:
@@ -52,7 +52,7 @@ def parse_string(
     if dedent:
         source = textwrap.dedent(source)
     file = io.StringIO(source)
-    return run_parser(file, parser_class, verbose=verbose)  # type: ignore # typeshed issue #3515
+    return run_parser(file, parser_class, verbose=verbose)  # type: ignore[arg-type] # typeshed issue #3515
 
 
 def make_parser(source: str) -> Type[Parser]:
@@ -116,7 +116,7 @@ def generate_parser_c_extension(
 def print_memstats() -> bool:
     MiB: Final = 2**20
     try:
-        import psutil  # type: ignore
+        import psutil  # type: ignore[import]
     except ImportError:
         return False
     print("Memory stats:")