[Python-checkins] gh-104504: cases generator: Add `--warn-unreachable` to the mypy config (#108112)
AlexWaygood
webhook-mailer at python.org
Sun Aug 20 19:40:44 EDT 2023
https://github.com/python/cpython/commit/05ef4ca94c694bc50e6fd221fe648d05d227f3a4
commit: 05ef4ca94c694bc50e6fd221fe648d05d227f3a4
branch: main
author: Alex Waygood <Alex.Waygood at Gmail.com>
committer: AlexWaygood <Alex.Waygood at Gmail.com>
date: 2023-08-21T00:40:41+01:00
summary:
gh-104504: cases generator: Add `--warn-unreachable` to the mypy config (#108112)
files:
A Tools/cases_generator/_typing_backports.py
M Tools/cases_generator/analysis.py
M Tools/cases_generator/generate_cases.py
M Tools/cases_generator/mypy.ini
diff --git a/Tools/cases_generator/_typing_backports.py b/Tools/cases_generator/_typing_backports.py
new file mode 100644
index 0000000000000..c2aa50804cefe
--- /dev/null
+++ b/Tools/cases_generator/_typing_backports.py
@@ -0,0 +1,15 @@
+"""Backports from newer versions of the typing module.
+
+We backport these features here so that Python can still build
+while using an older Python version for PYTHON_FOR_REGEN.
+"""
+
+from typing import NoReturn
+
+
+def assert_never(obj: NoReturn) -> NoReturn:
+ """Statically assert that a line of code is unreachable.
+
+ Backport of typing.assert_never (introduced in Python 3.11).
+ """
+ raise AssertionError(f"Expected code to be unreachable, but got: {obj}")
diff --git a/Tools/cases_generator/analysis.py b/Tools/cases_generator/analysis.py
index 48f2db981c95b..72fb2d761dbfa 100644
--- a/Tools/cases_generator/analysis.py
+++ b/Tools/cases_generator/analysis.py
@@ -2,6 +2,7 @@
import sys
import typing
+from _typing_backports import assert_never
from flags import InstructionFlags, variable_used
from formatting import prettify_filename, UNUSED
from instructions import (
@@ -172,7 +173,7 @@ def parse_file(self, filename: str, instrs_idx: dict[str, int]) -> None:
self.pseudos[name] = thing
self.everything.append(thing)
case _:
- typing.assert_never(thing)
+ assert_never(thing)
if not psr.eof():
raise psr.make_syntax_error(f"Extra stuff at the end of {filename}")
@@ -368,7 +369,7 @@ def analyze_macro(self, macro: parsing.Macro) -> MacroInstruction:
# SAVE_IP in a macro is a no-op in Tier 1
flags.add(instr.instr_flags)
case _:
- typing.assert_never(component)
+ assert_never(component)
format = "IB" if flags.HAS_ARG_FLAG else "IX"
if offset:
format += "C" + "0" * (offset - 1)
@@ -409,5 +410,5 @@ def check_macro_components(
case parsing.CacheEffect():
components.append(uop)
case _:
- typing.assert_never(uop)
+ assert_never(uop)
return components
diff --git a/Tools/cases_generator/generate_cases.py b/Tools/cases_generator/generate_cases.py
index de31129ac0548..7b1880b98a8fe 100644
--- a/Tools/cases_generator/generate_cases.py
+++ b/Tools/cases_generator/generate_cases.py
@@ -13,6 +13,7 @@
from collections.abc import Iterator
import stacking # Early import to avoid circular import
+from _typing_backports import assert_never
from analysis import Analyzer
from formatting import Formatter, list_effect_size
from flags import InstructionFlags, variable_used
@@ -146,7 +147,7 @@
class Generator(Analyzer):
def get_stack_effect_info(
self, thing: parsing.InstDef | parsing.Macro | parsing.Pseudo
- ) -> tuple[AnyInstruction | None, str | None, str | None]:
+ ) -> tuple[AnyInstruction | None, str, str]:
def effect_str(effects: list[StackEffect]) -> str:
n_effect, sym_effect = list_effect_size(effects)
if sym_effect:
@@ -154,8 +155,6 @@ def effect_str(effects: list[StackEffect]) -> str:
return str(n_effect)
instr: AnyInstruction | None
- popped: str | None
- pushed: str | None
match thing:
case parsing.InstDef():
if thing.kind != "op" or self.instrs[thing.name].is_viable_uop():
@@ -171,10 +170,9 @@ def effect_str(effects: list[StackEffect]) -> str:
popped, pushed = stacking.get_stack_effect_info_for_macro(instr)
case parsing.Pseudo():
instr = self.pseudo_instrs[thing.name]
- popped = pushed = None
# Calculate stack effect, and check that it's the the same
# for all targets.
- for target in self.pseudos[thing.name].targets:
+ for idx, target in enumerate(self.pseudos[thing.name].targets):
target_instr = self.instrs.get(target)
# Currently target is always an instr. This could change
# in the future, e.g., if we have a pseudo targetting a
@@ -182,14 +180,13 @@ def effect_str(effects: list[StackEffect]) -> str:
assert target_instr
target_popped = effect_str(target_instr.input_effects)
target_pushed = effect_str(target_instr.output_effects)
- if pushed is None:
- assert popped is None
+ if idx == 0:
popped, pushed = target_popped, target_pushed
else:
assert popped == target_popped
assert pushed == target_pushed
case _:
- typing.assert_never(thing)
+ assert_never(thing)
return instr, popped, pushed
@contextlib.contextmanager
@@ -209,7 +206,6 @@ def write_stack_effect_functions(self) -> None:
continue
instr, popped, pushed = self.get_stack_effect_info(thing)
if instr is not None:
- assert popped is not None and pushed is not None
popped_data.append((instr, popped))
pushed_data.append((instr, pushed))
@@ -379,7 +375,6 @@ def write_metadata(self, metadata_filename: str, pymetadata_filename: str) -> No
# Compute the set of all instruction formats.
all_formats: set[str] = set()
for thing in self.everything:
- format: str | None
match thing:
case OverriddenInstructionPlaceHolder():
continue
@@ -388,17 +383,15 @@ def write_metadata(self, metadata_filename: str, pymetadata_filename: str) -> No
case parsing.Macro():
format = self.macro_instrs[thing.name].instr_fmt
case parsing.Pseudo():
- format = None
- for target in self.pseudos[thing.name].targets:
+ for idx, target in enumerate(self.pseudos[thing.name].targets):
target_instr = self.instrs.get(target)
assert target_instr
- if format is None:
+ if idx == 0:
format = target_instr.instr_fmt
else:
assert format == target_instr.instr_fmt
- assert format is not None
case _:
- typing.assert_never(thing)
+ assert_never(thing)
all_formats.add(format)
# Turn it into a sorted list of enum values.
@@ -488,7 +481,7 @@ def write_metadata(self, metadata_filename: str, pymetadata_filename: str) -> No
self.pseudo_instrs[thing.name]
)
case _:
- typing.assert_never(thing)
+ assert_never(thing)
with self.metadata_item(
"const struct opcode_macro_expansion "
@@ -525,7 +518,7 @@ def write_metadata(self, metadata_filename: str, pymetadata_filename: str) -> No
case parsing.Pseudo():
pass
case _:
- typing.assert_never(thing)
+ assert_never(thing)
with self.metadata_item(
"const char * const _PyOpcode_uop_name[OPCODE_UOP_NAME_SIZE]", "=", ";"
@@ -774,7 +767,7 @@ def write_instructions(
case parsing.Pseudo():
pass
case _:
- typing.assert_never(thing)
+ assert_never(thing)
print(
f"Wrote {n_instrs} instructions and {n_macros} macros "
@@ -818,7 +811,7 @@ def write_executor_instructions(
case parsing.Pseudo():
pass
case _:
- typing.assert_never(thing)
+ assert_never(thing)
print(
f"Wrote {n_instrs} instructions and {n_uops} ops to {executor_filename}",
file=sys.stderr,
@@ -850,7 +843,7 @@ def write_abstract_interpreter_instructions(
case parsing.Pseudo():
pass
case _:
- typing.assert_never(thing)
+ assert_never(thing)
print(
f"Wrote some stuff to {abstract_interpreter_filename}",
file=sys.stderr,
diff --git a/Tools/cases_generator/mypy.ini b/Tools/cases_generator/mypy.ini
index 7480841bf07ed..54ccb8c5c1a3a 100644
--- a/Tools/cases_generator/mypy.ini
+++ b/Tools/cases_generator/mypy.ini
@@ -2,13 +2,12 @@
files = Tools/cases_generator/
pretty = True
+# Make sure Python can still be built
+# using Python 3.10 for `PYTHON_FOR_REGEN`...
python_version = 3.10
-# Be strict:
+# ...And be strict:
strict = True
strict_concatenate = True
enable_error_code = ignore-without-code,redundant-expr,truthy-bool
-
-# Don't enable this one yet;
-# it has a lot of false positives on `cases_generator`
-warn_unreachable = False
+warn_unreachable = True
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