Kconfig simplifies expressions, but redundant '&&' and '||' operators
involving constant symbols 'y' and 'n' are sometimes trimmed and
sometimes not.
[Test Code]
config DEP
def_bool y
config A
bool "A"
depends on DEP && y
config B
bool "B"
depends on DEP && y && y
[Result]
$ make helpnewconfig
[ snip ]
-----
There is no help available for this option.
Symbol: A [=n]
Type : bool
Defined at Kconfig:4
Prompt: A
Depends on: DEP [=y] && y [=y]
Location:
-> A (A [=n])
-----
-----
There is no help available for this option.
Symbol: B [=n]
Type : bool
Defined at Kconfig:8
Prompt: B
Depends on: DEP [=y]
Location:
-> B (B [=n])
-----
The dependency for A, 'DEP && y', remains as-is, while that for B,
'DEP && y && y', has been reduced to 'DEP'.
Currently, expr_eliminate_dups() calls expr_eliminate_yn() only when
trans_count != 0, in other words, only when expr_eliminate_dups1() has
trimmed at least one leaf. It fails to trim a single '&& y', etc.
To fix this inconsistent behavior, expr_eliminate_yn() should be called
at least once even if no leaf has been trimmed.
Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx>
---
scripts/kconfig/expr.c | 7 ++-----
1 file changed, 2 insertions(+), 5 deletions(-)
diff --git a/scripts/kconfig/expr.c b/scripts/kconfig/expr.c
index 6d4b5a5a1e62..b2dfd3123a5d 100644
--- a/scripts/kconfig/expr.c
+++ b/scripts/kconfig/expr.c
@@ -637,7 +637,7 @@ struct expr *expr_eliminate_dups(struct expr *e)
return e;
oldcount = trans_count;
- while (1) {
+ do {
trans_count = 0;
switch (e->type) {
case E_OR: case E_AND:
@@ -645,11 +645,8 @@ struct expr *expr_eliminate_dups(struct expr *e)
default:
;
}
- if (!trans_count)
- /* No simplifications done in this pass. We're done */
- break;
e = expr_eliminate_yn(e);
- }
+ } while (trans_count); /* repeat until we get no more simplifications */
trans_count = oldcount;
return e;
}
--
2.43.0
