testsuite: Simplify kernel32 glue logic

On Windows the testsuite driver calls kernel32 to set the current
terminal codepage. The previous implementation of this was significantly
more complex than necessary, and was wrong in the case of MSYS2, which
requires that we explicitly load the library using the name of its
DLL, including its file extension.

Test Plan: Validate on Windows

Reviewers: austin, RyanGlScott, Phyx

Reviewed By: RyanGlScott, Phyx

Subscribers: thomie

Differential Revision: https://phabricator.haskell.org/D2641

GHC Trac Issues: #12661

1 files changed, 6 insertions, 5 deletions

diff --git a/testsuite/driver/runtests.py b/testsuite/driver/runtests.py
index f36725efd5..c97323b810 100644
--- a/testsuite/driver/runtests.py
+++ b/testsuite/driver/runtests.py
@@ -160,17 +160,18 @@ if windows:
 if windows:
     import ctypes
     # Windows and mingw* Python provide windll, msys2 python provides cdll.
-    if hasattr(ctypes, 'windll'):
-        mydll = ctypes.windll
+    if hasattr(ctypes, 'WinDLL'):
+        mydll = ctypes.WinDLL
     else:
-        mydll = ctypes.cdll
+        mydll = ctypes.CDLL
 
     # This actually leaves the terminal in codepage 65001 (UTF8) even
     # after python terminates. We ought really remember the old codepage
     # and set it back.
-    if mydll.kernel32.SetConsoleCP(65001) == 0:
+    kernel32 = mydll('kernel32.dll')
+    if kernel32.SetConsoleCP(65001) == 0:
         raise Exception("Failure calling SetConsoleCP(65001)")
-    if mydll.kernel32.SetConsoleOutputCP(65001) == 0:
+    if kernel32.SetConsoleOutputCP(65001) == 0:
         raise Exception("Failure calling SetConsoleOutputCP(65001)")
 else:
     # Try and find a utf8 locale to use