cffi: run stubtest on Windows

stubs/cffi/@tests/stubtest_allowlist.txt

@@ -1,6 +1,3 @@
-# technically exists on all OSs, but crashes on all but windows
-cffi.(api.)?FFI.getwinerror
-
 # added dynamically and not detected by stubtest
 cffi.(api.)?FFI.CData
 cffi.(api.)?FFI.CType
@@ -11,4 +8,4 @@ cffi.vengine_cpy.__warningregistry__
 
 # Unnecessary re-exports
 cffi.cparser.COMMON_TYPES
-cffi.verifier.__version_verifier_modules__
+cffi.verifier.__version_verifier_modules__

stubs/cffi/@tests/stubtest_allowlist_darwin.txt

@@ -0,0 +1,2 @@
+# Technically exists on all OSs, but crashes on all but Windows. So we hide it in stubs
+cffi.(api.)?FFI.getwinerror

stubs/cffi/@tests/stubtest_allowlist_linux.txt

@@ -0,0 +1,2 @@
+# Technically exists on all OSs, but crashes on all but Windows. So we hide it in stubs
+cffi.(api.)?FFI.getwinerror

stubs/cffi/METADATA.toml

@@ -2,3 +2,5 @@ version = "1.15.*"
 
 [tool.stubtest]
 ignore_missing_stub = false
+# linux and darwin are mostly equivalent, except for a single `RTLD_DEEPBIND` variable
+platforms = ["linux", "win32"]

stubs/cffi/_cffi_backend.pyi

@@ -18,8 +18,9 @@ RTLD_GLOBAL: int
 RTLD_LAZY: int
 RTLD_LOCAL: int
 RTLD_NOW: int
-if sys.platform != "win32":
+if sys.platform == "linux":
     RTLD_DEEPBIND: int
+if sys.platform != "win32":
     RTLD_NODELETE: int
     RTLD_NOLOAD: int
 

stubs/cffi/cffi/api.pyi

@@ -72,6 +72,7 @@ class FFI:
     @overload
     def gc(self, cdata: CData, destructor: None, size: int = ...) -> None: ...
     def verify(self, source: str = ..., tmpdir: str | None = ..., **kwargs: Any) -> _cffi_backend.Lib: ...
+    # Technically exists on all OSs, but crashes on all but Windows. So we hide it in stubs
     if sys.platform == "win32":
         def getwinerror(self, code: int = ...) -> tuple[int, str] | None: ...