feat: Fix pattern type mismatches for bindings, enable pattern type mismatch diagnostics again #14732
Conversation
rustbot
added
the
S-waiting-on-review
HKalbasi
force-pushed
the
pat-type-mismatch
branch
from
8e3dc0d
to
36c9d5c
Compare
| /// It also includes the changes that binding mode makes in the type. For example in | ||
| /// `let ref x @ Some(_) = None` the result of `type_of_pat` is `Option<T>` but the result | ||
| /// of this function is `&mut Option<T>` | ||
| pub fn type_of_binding_in_pat(&self, pat: &ast::IdentPat) -> Option<Type> { |
There was a problem hiding this comment.
Interesting thing to keep in mind that effectively pattern and binding are not always equal in a sense
| @@ -148,7 +148,6 @@ struct Struct { | |||
| field: &'static str, | |||
| } | |||
| fn foo(s @ Struct { field, .. }: &Struct) {} | |||
| //^^^^^^^^^^^^^^^^^^^^^^^^ref | |||
There was a problem hiding this comment.
This seems wrong to me? s is being bound by reference so the ref mode should still be here
There was a problem hiding this comment.
I think s here is binding by moving the reference itself, not binding by ref the thing inside of reference. This example makes the difference clear:
let t @ T = &&&T; // type is `&&&T`, binding mode is `move`
let (t @ T,) = &&&(T,); // type is `&T`, binding mode is `ref`There was a problem hiding this comment.
Aha, turns out I completely misunderstood how binding modes worked for @ bindings! I think you are right here (at least judging from testing with == to avoid coercions from messing things up).
That also explains the pattern type mismatches now. Thanks for clarifying
|
@bors r+ |
|
Also, what do tuples have to do with this PR, isn't this fixing incorrect type inference for bindings? |
|
☀️ Test successful - checks-actions |
Veykril
changed the title
|
The main change in this PR is that |
Reduces pattern type mismatches on self to 4