Bug #10388
closedOperator precedence problem in multiple assignment (massign)
Description
I understand it wouldn't be easy to fix this, but since I happened to find it here it goes.
-
a, b = c = 1, 2
is currently taken asa, b = (c = 1), 2
; I'd expect it to be taken asa, b = (c = 1, 2)
. -
a, b = *c = 1, 2
is currently taken asa, b = *(c = 1), 2
; I'd expect it to be taken asa, b = *(c = 1, 2)
or evena, b = (*c = 1, 2)
. -
a, b = c, d = 1, 2
is currently taken asa, b = (c), (d = 1), 2
; I'd expect it to be taken asa, b = (c, d = 1, 2)
.
Should they be fixed/changed or not, issuing a warning would be greatly helpful.
Updated by jeremyevans0 (Jeremy Evans) about 5 years ago
I tried working on this a couple weeks ago and I don't believe the current LALR(1) parser can support it. Attempting to modify the parser to support the behavior you desire leads to many shift/reduce or reduce/reduce conflicts. It is possible that switching from the default LALR(1) parser to a GLR parser (which bison also supports) may allow for the behavior your desire, but I'm not sure what the ramifications of that are. It's also possible there is a way to introduce this behavior with the existing LALR(1) parser, and I am just not aware of it, as I do not have much experience in this area.
Updated by hsbt (Hiroshi SHIBATA) almost 5 years ago
- Tags set to unfixable, parser
Updated by matz (Yukihiro Matsumoto) almost 5 years ago
We are not going to change the behavior. We may warn (with -W
) if we see the simple assignments on the right-hand side of multiple assignments.
Matz.
Updated by matz (Yukihiro Matsumoto) almost 5 years ago
- Status changed from Open to Rejected