Remove the package_data.dlls setup.cfg entry.

See changelog for details.

DLLs won't end up in the source tree unless one explicitly copies them
there, so let's assume that whoever does this knows what they're doing.

INSTALL.rst

@@ -284,6 +284,9 @@ There are a few possibilities to build Matplotlib on Windows:
 * Wheels by using conda packages (see below)
 * Conda packages (see below)
 
+If you are building your own Matplotlib wheels (or sdists), note that any DLLs
+that you copy into the source tree will be packaged too.
+
 Wheel builds using conda packages
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
@@ -304,7 +307,6 @@ repository::
 
   build_alllocal.cmd
 
-
 Conda packages
 ^^^^^^^^^^^^^^
 

doc/api/next_api_changes/2019-05-30-AL.rst

@@ -0,0 +1,10 @@
+Changes to the Matplotlib build
+```````````````````````````````
+
+Previously, it was possible to package Windows DLLs into the Maptlotlib
+wheel (or sdist) by copying them into the source tree and setting the
+``package_data.dlls`` entry in ``setup.cfg``.
+
+DLLs copied in the source tree are now always packaged; the
+``package_data.dlls`` entry has no effect anymore.  If you do not want to
+include the DLLs, don't copy them into the source tree.

setup.cfg.template

@@ -66,9 +66,3 @@
 # modules.  The default is determined by fallback.
 #
 #backend = Agg
-
-[package_data]
-# Package additional files found in the lib/matplotlib directories.
-#
-# On Windows, package DLL files.
-#dlls = True

setup.py

@@ -75,8 +75,6 @@
     setupext.BackendAgg(),
     setupext.BackendTkAgg(),
     setupext.BackendMacOSX(),
-    'Optional package data',
-    setupext.Dlls(),
     ]
 
 

setupext.py

@@ -401,6 +401,7 @@ def get_package_data(self):
                 *_pkg_data_helper('matplotlib', 'mpl-data/images'),
                 *_pkg_data_helper('matplotlib', 'mpl-data/stylelib'),
                 *_pkg_data_helper('matplotlib', 'backends/web_backend'),
+                '*.dll',  # Only actually matters on Windows.
             ],
         }
 
@@ -816,35 +817,3 @@ def get_extension(self):
         if platform.python_implementation().lower() == 'pypy':
             ext.extra_compile_args.append('-DPYPY=1')
         return ext
-
-
-class OptionalPackageData(OptionalPackage):
-    config_category = "package_data"
-
-
-class Dlls(OptionalPackageData):
-    """
-    On Windows, this packages any DLL files that can be found in the
-    lib/matplotlib/* directories.
-    """
-    name = "dlls"
-
-    def check(self):
-        if sys.platform != 'win32':
-            raise CheckFailed("Microsoft Windows only")
-        return super().check()
-
-    def get_package_data(self):
-        return {'': ['*.dll']}
-
-    @classmethod
-    def get_config(cls):
-        """
-        Look at `setup.cfg` and return one of ["auto", True, False] indicating
-        if the package is at default state ("auto"), forced by the user (True)
-        or opted-out (False).
-        """
-        try:
-            return config.getboolean(cls.config_category, cls.name)
-        except Exception:
-            return False  # <-- default