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Commit fbe98bb9ed3d ("kconfig: Fix defconfig when one choice menu
selects options that another choice menu depends on") fixed defconfig
when two choices interact (i.e. calculating the visibility of a choice
requires to calculate another choice).
The test code in that commit log was based on the real world example,
and complicated. So, I shrunk it down to the following:
defconfig.choice:
---8<---
CONFIG_CHOICE_VAL0=y
---8<---
---8<---
config MODULES
def_bool y
option modules
choice
prompt "Choice"
config CHOICE_VAL0
tristate "Choice 0"
config CHOICE_VAL1
tristate "Choice 1"
endchoice
choice
prompt "Another choice"
depends on CHOICE_VAL0
config DUMMY
bool "dummy"
endchoice
---8<---
Prior to commit fbe98bb9ed3d,
$ scripts/kconfig/conf --defconfig=defconfig.choice Kconfig.choice
resulted in:
CONFIG_MODULES=y
CONFIG_CHOICE_VAL0=m
# CONFIG_CHOICE_VAL1 is not set
CONFIG_DUMMY=y
where the expected result would be:
CONFIG_MODULES=y
CONFIG_CHOICE_VAL0=y
# CONFIG_CHOICE_VAL1 is not set
CONFIG_DUMMY=y
Roughly, this weird behavior happened like this:
Symbols are calculated a couple of times. First, all symbols are
calculated in conf_read(). The first 'choice' is evaluated to 'y'
due to the SYMBOL_DEF_USER flag, but sym_calc_choice() clears it
unless all of its choice values are explicitly set by the user.
conf_set_all_new_symbols() clears all SYMBOL_VALID flags. Then, only
choices are calculated. Here, the SYMBOL_DEF_USER for the first choice
has been forgotten, so it is evaluated to 'm'. set_all_choice_values()
sets SYMBOL_DEF_USER again to choice symbols.
When calculating the second choice, due to 'depends on CHOICE_VAL0',
it triggers the calculation of CHOICE_VAL0. As a result, SYMBOL_VALID
is set for CHOICE_VAL0.
Symbols except choices get the final chance of re-calculation in
conf_write(). In a normal case, CHOICE_VAL0 would be re-calculated,
then the first choice would be indirectly re-calculated with the
SYMBOL_DEF_USER which has been recalled by set_all_choice_values(),
which would be evaluated to 'y'. But, in this case, CHOICE_VAL0 has
already been marked as SYMBOL_VALID, so this re-calculation does not
happen. Then, =m from the conf_set_all_new_symbols() phase is written
out to the .config file.
Add a unit test for this naive case.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Ulf Magnusson <ulfalizer@gmail.com>
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