use taskgroup to avoid cursed cpython bug (#209)

hauntsaninja · web-flow · commit 25a87147434a · 2025-09-16T13:08:54.000-07:00
Fixes #207 python/cpython#103847
diff --git a/mypy_primer/main.py b/mypy_primer/main.py
@@ -390,36 +390,39 @@ async def primer(ARGS: _Args) -> int:
         old_typeshed_dir=old_typeshed_dir,
     )
 
-    results = [
-        project.primer_result(
-            new_type_checker=new_type_checker,
-            old_type_checker=old_type_checker,
-            new_typeshed=new_typeshed_dir,
-            old_typeshed=old_typeshed_dir,
-            new_prepend_path=ARGS.new_prepend_path,
-            old_prepend_path=ARGS.old_prepend_path,
-        )
-        for project in projects
-    ]
-    retcode = 0
-    for result_fut in asyncio.as_completed(results):
-        result = await result_fut
-        if ARGS.old_success and not result.old_result.success:
-            continue
-        if ARGS.output == "full":
-            print(result.format_full())
-        elif ARGS.output == "diff":
-            print(result.format_diff_only())
-        elif ARGS.output == "concise":
-            # using ARGS.output == "concise" also causes us to:
-            # - always pass in --no-pretty and --no-error-summary
-            concise = result.format_concise()
-            if concise:
-                print(concise)
-                print()
-        if not retcode and result.diff:
-            retcode = 1
-    return retcode
+    async with asyncio.TaskGroup() as tg:
+        results = [
+            tg.create_task(
+                project.primer_result(
+                    new_type_checker=new_type_checker,
+                    old_type_checker=old_type_checker,
+                    new_typeshed=new_typeshed_dir,
+                    old_typeshed=old_typeshed_dir,
+                    new_prepend_path=ARGS.new_prepend_path,
+                    old_prepend_path=ARGS.old_prepend_path,
+                )
+            )
+            for project in projects
+        ]
+        retcode = 0
+        for result_fut in asyncio.as_completed(results):
+            result = await result_fut
+            if ARGS.old_success and not result.old_result.success:
+                continue
+            if ARGS.output == "full":
+                print(result.format_full())
+            elif ARGS.output == "diff":
+                print(result.format_diff_only())
+            elif ARGS.output == "concise":
+                # using ARGS.output == "concise" also causes us to:
+                # - always pass in --no-pretty and --no-error-summary
+                concise = result.format_concise()
+                if concise:
+                    print(concise)
+                    print()
+            if not retcode and result.diff:
+                retcode = 1
+        return retcode
 
 
 def main() -> None:
diff --git a/pyproject.toml b/pyproject.toml
@@ -4,7 +4,7 @@ version = "0.1.0"
 authors = [{ name = "Shantanu Jain" }, { email = "hauntsaninja@gmail.com" }]
 description = "Run mypy over millions of lines of code"
 readme = "README.md"
-requires-python = ">=3.10"
+requires-python = ">=3.11"
 license = {file = "LICENSE"}
 classifiers = [
     "Intended Audience :: Developers",
diff --git a/test.sh b/test.sh
@@ -3,7 +3,7 @@ set -ex
 uv run isort --diff --check --quiet .
 uv run black --diff --check --quiet .
 uv run flake8 --max-line-length=100 --ignore=E203,E501,W503 $(git ls-files | grep "py$")
-uv run mypy -p mypy_primer --strict --python-version 3.10
+uv run mypy -p mypy_primer --strict --python-version 3.11
 # check we have unique projects
 uv run python -c 'from mypy_primer.projects import get_projects; get_projects()'
 # this check was meant to ensure we could programmatically update the projects
