Issue #20035: Reimplement tkinter._fix module as a C function.

The new private C function makes no permanent changes to the environment
and is #ifdef'd out on non-Windows platforms.

Lib/tkinter/__init__.py

@@ -31,9 +31,6 @@ tk.mainloop()
 """
 
 import sys
-if sys.platform == "win32":
-    # Attempt to configure Tcl/Tk without requiring PATH
-    from tkinter import _fix
 
 import _tkinter # If this fails your Python may not be configured for Tk
 TclError = _tkinter.TclError

Lib/tkinter/_fix.py

@@ -1,78 +0,0 @@
-import sys, os
-
-# Delay import _tkinter until we have set TCL_LIBRARY,
-# so that Tcl_FindExecutable has a chance to locate its
-# encoding directory.
-
-# Unfortunately, we cannot know the TCL_LIBRARY directory
-# if we don't know the tcl version, which we cannot find out
-# without import Tcl. Fortunately, Tcl will itself look in
-# <TCL_LIBRARY>\..\tcl<TCL_VERSION>, so anything close to
-# the real Tcl library will do.
-
-# Expand symbolic links on Vista
-try:
-    import ctypes
-    ctypes.windll.kernel32.GetFinalPathNameByHandleW
-except (ImportError, AttributeError):
-    def convert_path(s):
-        return s
-else:
-    def convert_path(s):
-        if isinstance(s, bytes):
-            s = s.decode("mbcs")
-        hdir = ctypes.windll.kernel32.\
-            CreateFileW(s, 0x80,    # FILE_READ_ATTRIBUTES
-                        1,          # FILE_SHARE_READ
-                        None, 3,    # OPEN_EXISTING
-                        0x02000000, # FILE_FLAG_BACKUP_SEMANTICS
-                        None)
-        if hdir == -1:
-            # Cannot open directory, give up
-            return s
-        buf = ctypes.create_unicode_buffer("", 32768)
-        res = ctypes.windll.kernel32.\
-            GetFinalPathNameByHandleW(hdir, buf, len(buf),
-                                      0) # VOLUME_NAME_DOS
-        ctypes.windll.kernel32.CloseHandle(hdir)
-        if res == 0:
-            # Conversion failed (e.g. network location)
-            return s
-        s = buf[:res]
-        # Ignore leading \\?\
-        if s.startswith("\\\\?\\"):
-            s = s[4:]
-        if s.startswith("UNC"):
-            s = "\\" + s[3:]
-        return s
-
-prefix = os.path.join(sys.base_prefix,"tcl")
-if not os.path.exists(prefix):
-    # devdir/externals/tcltk/lib
-    prefix = os.path.join(sys.base_prefix, "externals", "tcltk", "lib")
-    prefix = os.path.abspath(prefix)
-# if this does not exist, no further search is needed
-if os.path.exists(prefix):
-    prefix = convert_path(prefix)
-    if "TCL_LIBRARY" not in os.environ:
-        for name in os.listdir(prefix):
-            if name.startswith("tcl"):
-                tcldir = os.path.join(prefix,name)
-                if os.path.isdir(tcldir):
-                    os.environ["TCL_LIBRARY"] = tcldir
-    # Compute TK_LIBRARY, knowing that it has the same version
-    # as Tcl
-    import _tkinter
-    ver = str(_tkinter.TCL_VERSION)
-    if "TK_LIBRARY" not in os.environ:
-        v = os.path.join(prefix, 'tk'+ver)
-        if os.path.exists(os.path.join(v, "tclIndex")):
-            os.environ['TK_LIBRARY'] = v
-    # We don't know the Tix version, so we must search the entire
-    # directory
-    if "TIX_LIBRARY" not in os.environ:
-        for name in os.listdir(prefix):
-            if name.startswith("tix"):
-                tixdir = os.path.join(prefix,name)
-                if os.path.isdir(tixdir):
-                    os.environ["TIX_LIBRARY"] = tixdir