Merge branch 'py38-windows-dll-path' into 'master'

Try to discover CUDA binary path, to add to Py3.8's DLL path (Closes inducergh-213)

See merge request inducer/pycuda!17

pycuda/driver.py

@@ -1,6 +1,63 @@
-from __future__ import absolute_import
-from __future__ import print_function
+from __future__ import absolute_import, print_function
+
+import os
+import sys
+
 import six
+
+import numpy as np
+
+
+# {{{ add cuda lib dir to Python DLL path
+
+def _search_on_path(filenames):
+    """Find file on system path."""
+    # http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/52224
+
+    from os.path import exists, abspath, join
+    from os import pathsep, environ
+
+    search_path = environ["PATH"]
+
+    paths = search_path.split(pathsep)
+    for path in paths:
+        for filename in filenames:
+            if exists(join(path, filename)):
+                return abspath(join(path, filename))
+
+
+def _add_cuda_libdir_to_dll_path():
+    from os.path import join, dirname
+
+    cuda_path = os.environ.get("CUDA_PATH")
+
+    if cuda_path is not None:
+        os.add_dll_directory(join(cuda_path, 'bin'))
+        return
+
+    nvcc_path = _search_on_path(["nvcc.exe"])
+    if nvcc_path is not None:
+        os.add_dll_directory(dirname(nvcc_path))
+
+    from warnings import warn
+    warn("Unable to discover CUDA installation directory "
+            "while attempting to add it to Python's DLL path. "
+            "Either set the 'CUDA_PATH' environment variable "
+            "or ensure that 'nvcc.exe' is on the path.")
+
+
+try:
+    os.add_dll_directory
+except AttributeError:
+    # likely not on Py3.8 and Windows
+    # https://github.com/inducer/pycuda/issues/213
+    pass
+else:
+    _add_cuda_libdir_to_dll_path()
+
+# }}}
+
+
 try:
     from pycuda._driver import *  # noqa
 except ImportError as e:
@@ -11,9 +68,6 @@
                 "does not match the version of your CUDA driver.")
     raise
 
-import numpy as np
-import sys
-
 
 if sys.version_info >= (3,):
     _memoryview = memoryview