remove --diff option

docs/source/internal/utils.rst

@@ -66,11 +66,3 @@ The standard library's :func:`fnmatch.fnmatch` is excellent at deciding if a
 filename matches a single pattern. In our use case, however, we typically have
 a list of patterns and want to know if the filename matches any of them. This
 function abstracts that logic away with a little extra logic.
-
-.. autofunction:: flake8.utils.parse_unified_diff
-
-To handle usage of :option:`flake8 --diff`, |Flake8| needs to be able
-to parse the name of the files in the diff as well as the ranges indicated the
-sections that have been changed. This function either accepts the diff as an
-argument or reads the diff from standard-in. It then returns a dictionary with
-filenames as the keys and sets of line numbers as the value.

docs/source/user/options.rst

@@ -44,8 +44,6 @@ Index of Options
 
 - :option:`flake8 --count`
 
-- :option:`flake8 --diff`
-
 - :option:`flake8 --exclude`
 
 - :option:`flake8 --filename`
@@ -230,27 +228,6 @@ Options and their Descriptions
         count = True
 
 
-.. option:: --diff
-
-    :ref:`Go back to index <top>`
-
-    .. warning::
-
-        Due to hiding potential errors, this option is deprecated and will be
-        removed in a future version.
-
-    Use the unified diff provided on standard in to only check the modified
-    files and report errors included in the diff.
-
-    Command-line example:
-
-    .. prompt:: bash
-
-        git diff -u | flake8 --diff
-
-    This **can not** be specified in config files.
-
-
 .. option:: --exclude=<patterns>
 
     :ref:`Go back to index <top>`