Enable warn_unreachable = True for mypyc and all other files as well (#19050)

Achieves a todo, enabling warn_unreachable = True for `mypyc` and all
other files as well

Author: wyattscarpenter

misc/analyze_cache.py

@@ -41,7 +41,7 @@ def extract(chunks: Iterable[JsonDict]) -> Iterable[JsonDict]:
             if isinstance(chunk, dict):
                 yield chunk
                 yield from extract(chunk.values())
-            elif isinstance(chunk, list):
+            elif isinstance(chunk, list):  # type: ignore[unreachable] #TODO: is this actually unreachable, or are our types wrong?
                 yield from extract(chunk)
 
     yield from extract([chunk.data for chunk in chunks])
@@ -93,7 +93,7 @@ def compress(chunk: JsonDict) -> JsonDict:
     def helper(chunk: JsonDict) -> JsonDict:
         nonlocal counter
         if not isinstance(chunk, dict):
-            return chunk
+            return chunk  # type: ignore[unreachable] #TODO: is this actually unreachable, or are our types wrong?
 
         if len(chunk) <= 2:
             return chunk
@@ -124,7 +124,7 @@ def decompress(chunk: JsonDict) -> JsonDict:
 
     def helper(chunk: JsonDict) -> JsonDict:
         if not isinstance(chunk, dict):
-            return chunk
+            return chunk  # type: ignore[unreachable] #TODO: is this actually unreachable, or are our types wrong?
         if ".id" in chunk:
             return cache[chunk[".id"]]
 

misc/profile_check.py

@@ -78,22 +78,22 @@ def check_requirements() -> None:
     if sys.platform != "linux":
         # TODO: How to make this work on other platforms?
         sys.exit("error: Only Linux is supported")
-
-    try:
-        subprocess.run(["perf", "-h"], capture_output=True)
-    except (subprocess.CalledProcessError, FileNotFoundError):
-        print("error: The 'perf' profiler is not installed")
-        sys.exit(1)
-
-    try:
-        subprocess.run(["clang", "--version"], capture_output=True)
-    except (subprocess.CalledProcessError, FileNotFoundError):
-        print("error: The clang compiler is not installed")
-        sys.exit(1)
-
-    if not os.path.isfile("mypy_self_check.ini"):
-        print("error: Run this in the mypy repository root")
-        sys.exit(1)
+    else:  # fun fact/todo: we have to use else here, because of https://github.com/python/mypy/issues/10773
+        try:
+            subprocess.run(["perf", "-h"], capture_output=True)
+        except (subprocess.CalledProcessError, FileNotFoundError):
+            print("error: The 'perf' profiler is not installed")
+            sys.exit(1)
+
+        try:
+            subprocess.run(["clang", "--version"], capture_output=True)
+        except (subprocess.CalledProcessError, FileNotFoundError):
+            print("error: The clang compiler is not installed")
+            sys.exit(1)
+
+        if not os.path.isfile("mypy_self_check.ini"):
+            print("error: Run this in the mypy repository root")
+            sys.exit(1)
 
 
 def main() -> None:

mypy_self_check.ini

@@ -12,7 +12,4 @@ exclude = mypy/typeshed/|mypyc/test-data/|mypyc/lib-rt/
 enable_error_code = ignore-without-code,redundant-expr
 enable_incomplete_feature = PreciseTupleTypes
 show_error_code_links = True
-
-[mypy-mypy.*]
-# TODO: enable for `mypyc` and other files as well
 warn_unreachable = True