cmake: kconfig: Keep symbol names sorted in EXTRA_KCONFIG_OPTIONS
This makes checksum calculation over Kconfig fragments more consistent,
which prevents writing a new `.config` when nothing really changes.
To explain this, consider the following sequence:
1. west build . -DCONFIG_XXXX=y -DCONFIG_YYYY=y
2. west build . -DCONFIG_YYYY=y
3. west build . -DCONFIG_XXXX=y
At (1), we set new values for XXXX and YYYY, so the `.config` changes.
At (2), we set a value for YYYY, but it's the same value as before, so
the `.config` doesn't get overwritten.
At (3), we set a value for XXXX, but it's the same value as before, so
the `.config` shouldn't get overwritten... but it does. What happened?
The reason is that the generated `extra_kconfig_options.conf` fragment,
which is included in the checksum calculation, was being populated using
two sets of CMake cache variables:
- past assignments, prefixed with `CLI_${KCONFIG_NAMESPACE}_`.
- new assignments, prefixed with just `${KCONFIG_NAMESPACE}_`.
Usually, past assignments would appear before new assignments, because
the default `${KCONFIG_NAMESPACE}` is CONFIG, which goes after CLI in
alphabetical order. As a result, the contents of EXTRA_KCONFIG_OPTIONS
at (1) and (2):
CONFIG_XXXX=y
CONFIG_YYYY=y
were not identical to its contents at (3):
CONFIG_YYYY=y
CONFIG_XXXX=y
resulting in a different checksum.
This is resolved by stripping out the CLI prefix first, then effectively
"mergesorting" the past and new assignments, before starting to populate
EXTRA_KCONFIG_OPTIONS.
Signed-off-by: Grzegorz Swiderski <grzegorz.swiderski@nordicsemi.no>
1 file changed
