[Buildroot] [PATCH 1 of 6 v2] Config.in.legacy: update description

[Thomas Petazzoni <thomas.petazzoni@free-electrons.com>]

Hello Arnout,

As the author of the Config.in.legacy mechanism, it would be great if
you could review/ack the below patch.

Thanks,

Thomas

On Wed, 24 Jul 2013 09:22:58 +0200, Thomas De Schampheleire wrote:
> The existing comments in Config.in.legacy are not entirely in-line with
> current practice. The comments implies that BR2_LEGACY should not be set when
> the conversion from old-to-new symbol can be done automatically using the
> appropriate 'select' statements. However, none of the existing legacy options
> does it this way. Moreover, I think it's intentional that the user is notified
> of the change, so that the removal of the legacy options in later buildroot
> versions no longer poses a problem.
> 
> Additionally, I have added an example of how to handle the renaming of a string
> config option. Because a string option cannot 'select' something else, a wrapper
> symbol is needed of type bool.
> 
> Signed-off-by: Thomas De Schampheleire <thomas.de.schampheleire@gmail.com>
> 
> ---
> (v2): new patch in this series
> 
>  Config.in.legacy |  22 +++++++++++++++++-----
>  1 files changed, 17 insertions(+), 5 deletions(-)
> 
> diff --git a/Config.in.legacy b/Config.in.legacy
> --- a/Config.in.legacy
> +++ b/Config.in.legacy
> @@ -3,11 +3,10 @@
>  #
>  # When an existing Config.in symbol is removed, it should be added again in this
>  # file, and take appropriate action to approximate backward compatibility. If
> -# there is an equivalent (set of) new symbols, these can just be select'ed by
> -# the old symbol. This makes sure that running 'make oldconfig' will make things
> -# "just work" when upgrading to a new buildroot version. If the change is too
> -# fundamental and cannot be fixed by a simple select, then the old symbol should
> -# select BR2_LEGACY.  If that symbol is set, the build will issue an error.
> +# there is an equivalent (set of) new symbols, these should be select'ed by
> +# the old symbol. This will make the transition for the user more convenient.
> +# The old symbol should select BR2_LEGACY, so that the user is informed at
> +# build-time about selected legacy options.
>  #
>  # When adding legacy symbols to this file, add them to the front. The oldest
>  # symbols will be removed again after about two years.
> @@ -15,6 +14,19 @@
>  # The symbol should be copied as-is from the place where it was previously
>  # defined, but the help text should be removed or replaced with something that
>  # explains how to fix it.
> +# If the old symbol is of type string, and the symbol has been renamed, you
> +# should add it as a bool with another name (BR2_<foo>_WRAP), that defaults
> +# to y if the old string is not set at its default value. For example:
> +#     config BR2_FOO_STRING
> +#             string "Some foo string"
> +# would become:
> +#     config BR2_FOO_STRING_WRAP
> +#             bool "Foo string option has been renamed."
> +#             default y if BR2_FOO_STRING != ""
> +#             depends on BR2_LEGACY
> +#             help
> +#               <suitable help text>
> +#
>  
>  config BR2_LEGACY
>  	bool
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-- 
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com