fix: use ExprIsRead::Yes for rhs of binary operators#21654
fix: use ExprIsRead::Yes for rhs of binary operators#21654Albab-Hasan wants to merge 4 commits intorust-lang:masterfrom
ExprIsRead::Yes for rhs of binary operators#21654Conversation
rustbot
added
the
S-waiting-on-review
Albab-Hasan
force-pushed
the
fix/binop-rhs-never-coercion
branch
from
d91ef9c to
0bed4fb
Compare
both operands of binary operators (including compound assignments like `+=`) were inferred with `ExprIsRead::No`, which prevented divergence detection for place expressions of type `!`. this caused false type mismatches when a function's return type depended on the block diverging after something like `x += *never_ptr` or `let _ = *never_ptr + 1`. both operands of any binary operator are always consumed (read), so this uses `ExprIsRead::Yes` to be consistent with the ordinary assignment and let binding paths.
Albab-Hasan
force-pushed
the
fix/binop-rhs-never-coercion
branch
from
0bed4fb to
b3feb5f
Compare
| } | ||
|
|
||
| #[test] | ||
| fn binop_lhs_never_place_diverges() { |
There was a problem hiding this comment.
This... does not check what it declares?
There was a problem hiding this comment.
my bad. one sec, ill fix it
There was a problem hiding this comment.
Did you fix it?
yes
There was a problem hiding this comment.
How? It still does not test coercion in the LHS.
The other comment was my mistake.
There was a problem hiding this comment.
sorry i just switched to check_infer_with_mismatches thinking that showingthe inferred types was enough.
There was a problem hiding this comment.
It seems there is a misunderstanding. The LHS in the assignment a = b is a. Asserting that a never coercion happens in the LHS means something like *p += 1 where *p is *const !.
There was a problem hiding this comment.
This test is still not correct as there is no assignment now.
Albab-Hasan
force-pushed
the
fix/binop-rhs-never-coercion
branch
from
8006f04 to
2f12839
Compare
|
@ChayimFriedman2 hey, so im really confused rn.
I get this. i pushed the fix. but im not sure what ur trying to say in the first comment. the changes on lines 181 and 183 are in the _ => branch thats regular binops like + not assignments. both operands of + are consumed by |
|
@ChayimFriedman2 can i get some instructions or should i close this pr and work on one liners again? |
|
@ChayimFriedman2 sorry for wasting your time |
|
The change is good, only the test is problematic. A good test will be something like (not verified): let a: *const ! = 0 as _;
*a += 1; |
|
@ChayimFriedman2 ok ill try to fix the test |
|
@ChayimFriedman2 can you review the changes? the test is fixed |
3 participants
the rhs of binary operators (including compound assignments like
+=) was inferred withExprIsRead::No, which prevented divergence detection for place expressions of type!. this caused false type mismatches when a function's return type depended on the block diverging after something likex += *never_ptr. the rhs of any binary operator is always consumed (read), so this usesExprIsRead::Yesto be consistent with the ordinary assignment and let binding paths.