Fixes destination directory of data_files when 'pip install --target' is used (#4092) (#4152)

news/4092.bugfix

@@ -0,0 +1 @@
+Fixes destination directory of data_files when ``pip install --target`` is used.

pip/commands/install.py

@@ -313,14 +313,21 @@ class InstallCommand(RequirementCommand):
 
             purelib_dir = distutils_scheme('', home=temp_target_dir)['purelib']
             platlib_dir = distutils_scheme('', home=temp_target_dir)['platlib']
+            data_dir = distutils_scheme('', home=temp_target_dir)['data']
 
             if os.path.exists(purelib_dir):
                 lib_dir_list.append(purelib_dir)
             if os.path.exists(platlib_dir) and platlib_dir != purelib_dir:
                 lib_dir_list.append(platlib_dir)
+            if os.path.exists(data_dir):
+                lib_dir_list.append(data_dir)
 
             for lib_dir in lib_dir_list:
                 for item in os.listdir(lib_dir):
+                    if lib_dir == data_dir:
+                        ddir = os.path.join(data_dir, item)
+                        if any(s.startswith(ddir) for s in lib_dir_list[:-1]):
+                            continue
                     target_item_dir = os.path.join(options.target_dir, item)
                     if os.path.exists(target_item_dir):
                         if not options.upgrade:

tests/data/src/prjwithdatafile/prjwithdatafile/README.txt

@@ -0,0 +1,4 @@
+README
+======
+
+Test project file

tests/data/src/prjwithdatafile/setup.py

@@ -0,0 +1,12 @@
+# -*- coding: utf-8 -*-
+from setuptools import setup
+
+setup(
+    name='prjwithdatafile',
+    version="1.0",
+    packages=['prjwithdatafile'],
+    data_files=[
+        (r'packages1', ['prjwithdatafile/README.txt']),
+        (r'packages2', ['prjwithdatafile/README.txt'])
+    ]
+)

tests/functional/test_install_wheel.py

@@ -129,6 +129,42 @@ def test_install_wheel_with_target(script, data):
     )
 
 
+@pytest.mark.network
+def test_install_wheel_with_target_and_data_files(script, data):
+    """
+    Test for issue #4092. It will be checked that a data_files specification in
+    setup.py is handled correctly when a wheel is installed with the --target
+    option.
+
+    The setup() for the wheel 'prjwithdatafile-1.0-py2.py3-none-any.whl' is as
+    follows ::
+
+        setup(
+            name='prjwithdatafile',
+            version='1.0',
+            packages=['prjwithdatafile'],
+            data_files=[
+                (r'packages1', ['prjwithdatafile/README.txt']),
+                (r'packages2', ['prjwithdatafile/README.txt'])
+            ]
+        )
+    """
+    script.pip('install', 'wheel')
+    target_dir = script.scratch_path / 'prjwithdatafile'
+    package = data.packages.join("prjwithdatafile-1.0-py2.py3-none-any.whl")
+    result = script.pip('install', package,
+                        '-t', target_dir,
+                        '--no-index',
+                        expect_error=False)
+
+    assert (Path('scratch') / 'prjwithdatafile' / 'packages1' / 'README.txt'
+            in result.files_created), str(result)
+    assert (Path('scratch') / 'prjwithdatafile' / 'packages2' / 'README.txt'
+            in result.files_created), str(result)
+    assert (Path('scratch') / 'prjwithdatafile' / 'lib' / 'python'
+            not in result.files_created), str(result)
+
+
 def test_install_wheel_with_root(script, data):
     """
     Test installing a wheel using pip install --root