From 4602028ba2450903b63f043377cc63ac5e5e36de Mon Sep 17 00:00:00 2001
From: Ulf Magnusson <ulfalizer@gmail.com>
Date: Wed, 3 Oct 2018 07:19:43 +0200
Subject: genconfig: Allow writing a full .config without incremental build
 info

For projects that don't use incremental build information, it's a bit
wasteful to generate it just to get an updated .config file to include
in Makefiles. Add a '--config-out <filename>' option that just writes
the updated .config file, for those cases.

Also remove a redundant default=None argument for --sync-deps. None is
the default value.
---
 README.rst   | 17 ++++++++++-------
 genconfig.py | 25 ++++++++++++++++++++-----
 2 files changed, 30 insertions(+), 12 deletions(-)

diff --git a/README.rst b/README.rst
index 3c38839..44763be 100644
--- a/README.rst
+++ b/README.rst
@@ -121,7 +121,7 @@ Getting started
 3. Generate an initial configuration with e.g. ``menuconfig`` or
    ``alldefconfig``. The configuration is saved as ``.config`` by default.
 
-4. Run ``genconfig`` to generate a header file. By default, it is saved in
+4. Run ``genconfig`` to generate a header file. By default, it is saved as
    ``config.h``.
 
    Normally, ``genconfig`` would be run automatically as part of the build.
@@ -146,12 +146,15 @@ read configuration values from there. This is why ``n``-valued ``bool``/``trista
 values are written out as ``# CONFIG_FOO is not set`` (a Make comment) in ``.config``
 (allowing them to be tested with ``ifdef`` in Make).
 
-If you make use of this, you might want to pass ``--sync-deps`` to
-``genconfig`` and include ``deps/auto.conf`` in your Makefiles instead of
-including ``.config`` directly. This has the advantage that ``deps/auto.conf``
-will always be a "full" configuration file, even if ``.config`` is outdated.
-Otherwise, it might be necessary to run ``old(def)config`` or ``menuconfig``
-before rebuilding with an outdated configuration.
+If you make use of this, you might want to pass ``--config-out <filename>`` to
+``genconfig`` and include the generated configuration file instead of including
+``.config`` directly. This has the advantage that the generated configuration
+file will always be a "full" configuration file, even if ``.config`` is
+outdated. Otherwise, it might be necessary to run ``old(def)config`` or
+``menuconfig`` before rebuilding with an outdated ``.config``.
+
+If you use ``--sync-deps`` to generate incremental build information, you can
+include ``deps/auto.conf`` instead, which is also a full configuration file.
 
 Library documentation
 ---------------------
diff --git a/genconfig.py b/genconfig.py
index c0709e0..4fe84d6 100755
--- a/genconfig.py
+++ b/genconfig.py
@@ -36,7 +36,7 @@ def main():
         "--header-path",
         metavar="HEADER_FILE",
         default=DEFAULT_HEADER_PATH,
-        help="path for the generated header file (default: {})"
+        help="Path for the generated header file (default: {})"
              .format(DEFAULT_HEADER_PATH))
 
     parser.add_argument(
@@ -44,29 +44,44 @@ def main():
         dest="sync_deps_path",
         metavar="OUTPUT_DIR",
         nargs="?",
-        default=None,
         const=DEFAULT_SYNC_DEPS_PATH,
-        help="enable generation of build dependency information for "
+        help="Enable generation of build dependency information for "
              "incremental builds, optionally specifying the output path "
              "(default: {})".format(DEFAULT_SYNC_DEPS_PATH))
 
+    parser.add_argument(
+        "--config-out",
+        dest="config_path",
+        metavar="CONFIG_FILE",
+        help="Write the configuration to the specified filename. "
+             "This is useful if you include .config files in Makefiles, as "
+             "the generated configuration file will be a full .config file "
+             "even if .config is outdated. The generated configuration "
+             "matches what olddefconfig would produce. If you use "
+             "--sync-deps, you can include deps/auto.conf instead. "
+             "--config-out is meant for cases where incremental build "
+             "information isn't needed.")
+
     parser.add_argument(
         "kconfig_filename",
         metavar="KCONFIG_FILENAME",
         nargs="?",
         default="Kconfig",
-        help="top-level Kconfig file (default: Kconfig)")
+        help="Top-level Kconfig file (default: Kconfig)")
 
     args = parser.parse_args()
 
 
     kconf = kconfiglib.Kconfig(args.kconfig_filename)
-
     kconf.load_config(kconfiglib.standard_config_filename())
 
     kconf.write_autoconf(args.header_path)
+
     if args.sync_deps_path is not None:
         kconf.sync_deps(args.sync_deps_path)
 
+    if args.config_path is not None:
+        kconf.write_config(args.config_path)
+
 if __name__ == "__main__":
     main()
-- 
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