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kconfig: make 'imply' obey the direct dependency

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The 'imply' statement may create unmet direct dependency when the
implied symbol depends on m.

[Test Code]

  config FOO
          tristate "foo"
          imply BAZ

  config BAZ
          tristate "baz"
          depends on BAR

  config BAR
          def_tristate m

  config MODULES
          def_bool y
          option modules

If you set FOO=y, BAZ is also promoted to y, which results in the
following .config file:

  CONFIG_FOO=y
  CONFIG_BAZ=y
  CONFIG_BAR=m
  CONFIG_MODULES=y

This does not meet the dependency 'BAZ depends on BAR'.

Unlike 'select', what is worse, Kconfig never shows the
'WARNING: unmet direct dependencies detected for ...' for this case.

Because 'imply' is considered to be weaker than 'depends on', Kconfig
should take the direct dependency into account.

For clarification, describe this case in kconfig-language.rst too.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Nicolas Pitre <nico@fluxnic.net>
Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>
This commit is contained in:
Masahiro Yamada 2020-03-02 15:23:40 +09:00
parent def2fbffe6
commit 3a9dd3ecb2
2 changed files with 16 additions and 3 deletions
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15
Documentation/kbuild/kconfig-language.rst
View File

@ -159,11 +159,11 @@ applicable everywhere (see syntax).
Given the following example::
config FOO
tristate
tristate "foo"
imply BAZ
config BAZ
tristate
tristate "baz"
depends on BAR
The following values are possible:
@ -174,6 +174,9 @@ applicable everywhere (see syntax).
n y n N/m/y
m y m M/y/n
y y y Y/m/n
n m n N/m
m m m M/n
y m n M/n
y n * N
=== === ============= ==============
@ -191,6 +194,14 @@ applicable everywhere (see syntax).
...
}
Note: If the feature provided by BAZ is highly desirable for FOO,
FOO should imply not only BAZ, but also its dependency BAR::
config FOO
tristate "foo"
imply BAR
imply BAZ
- limiting menu display: "visible if" <expr>
This attribute is only applicable to menu blocks, if the condition is

4
scripts/kconfig/symbol.c
View File

@ -221,7 +221,7 @@ static void sym_calc_visibility(struct symbol *sym)
sym_set_changed(sym);
}
tri = no;
if (sym->implied.expr && sym->dir_dep.tri != no)
if (sym->implied.expr)
tri = expr_calc_value(sym->implied.expr);
if (tri == mod && sym_get_type(sym) == S_BOOLEAN)
tri = yes;
@ -394,6 +394,8 @@ void sym_calc_value(struct symbol *sym)
if (sym->implied.tri != no) {
sym->flags |= SYMBOL_WRITE;
newval.tri = EXPR_OR(newval.tri, sym->implied.tri);
newval.tri = EXPR_AND(newval.tri,
sym->dir_dep.tri);
}
}
calc_newval: