From 02bcbee245b9b5a0c75345ada0f1d7e70d19b3c0 Mon Sep 17 00:00:00 2001
From: Ian Cordasco <graffatcolmingov@gmail.com>
Date: Mon, 6 Jun 2016 19:46:29 -0500
Subject: [PATCH] Add --stdin-display-name to modify report output

---
 docs/source/user/options.rst | 24 ++++++++++++++++++++++++
 flake8/main/cli.py           |  7 +++++++
 flake8/style_guide.py        |  2 ++
 3 files changed, 33 insertions(+)

diff --git a/docs/source/user/options.rst b/docs/source/user/options.rst
index ce30bdf..e336daa 100644
--- a/docs/source/user/options.rst
+++ b/docs/source/user/options.rst
@@ -192,6 +192,30 @@
             another-example*.py
 
 
+.. option:: --stdin-display-name=<display_name>
+
+    Provide the name to use to report warnings and errors from code on stdin.
+
+    Instead of reporting an error as something like:
+
+    .. code::
+
+        stdin:82:73 E501 line too long
+
+    You can specify this option to have it report whatever value you want
+    instead of stdin.
+
+    This defaults to: ``stdin``
+
+    Command-line example:
+
+    .. prompt:: bash
+
+        cat file.py | flake8 --stdin-display-name=file.py -
+
+    This **can not** be specified in config files.
+
+
 .. option:: --format=<format>
 
     Select the formatter used to display errors to the user.
diff --git a/flake8/main/cli.py b/flake8/main/cli.py
index b426e1e..0b50e27 100644
--- a/flake8/main/cli.py
+++ b/flake8/main/cli.py
@@ -86,6 +86,13 @@ def register_default_options(option_manager):
              'separated list. (Default: %default)',
     )
 
+    add_option(
+        '--stdin-display-name', default='stdin',
+        help='The name used when reporting errors from code passed via stdin.'
+             ' This is useful for editors piping the file contents to flake8.'
+             ' (Default: %default)',
+    )
+
     # TODO(sigmavirus24): Figure out --first/--repeat
 
     add_option(
diff --git a/flake8/style_guide.py b/flake8/style_guide.py
index 57d86b2..6be9ff6 100644
--- a/flake8/style_guide.py
+++ b/flake8/style_guide.py
@@ -237,6 +237,8 @@ class StyleGuide(object):
         """Handle an error reported by a check."""
         error = Error(code, filename, line_number, column_number, text,
                       physical_line)
+        if error.filename is None or error.filename == '-':
+            error = error._replace(filename=self.options.stdin_display_name)
         error_is_selected = (self.should_report_error(error.code) is
                              Decision.Selected)
         is_not_inline_ignored = self.is_inline_ignored(error) is False