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obey line length limit (part 3)

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Tshepang Mbambo 2022-07-17 23:19:52 +02:00
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27
src/opaque-types-type-alias-impl-trait-inference.md
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@ -43,9 +43,14 @@ pub fn main() {
* `m::produce_singleton`
* `m::produce_doubleton`
* In the `main` function, the opaque type is out of scope:
* When `main` calls `m::produce_singleton`, it gets back a reference to the opaque type `Seq<i32>`.
* The `is_send` call checks that `Seq<i32>: Send`. `Send` is not listed amongst the bounds of the impl trait, but because of auto-trait leakage, we are able to infer that it holds.
* The for loop desugaring requires that `Seq<T>: IntoIterator`, which is provable from the bounds declared on `Seq<T>`.
* When `main` calls `m::produce_singleton`,
it gets back a reference to the opaque type `Seq<i32>`.
* The `is_send` call checks that `Seq<i32>:
Send`. `Send` is not listed amongst the bounds of the impl trait,
but because of auto-trait leakage,
we are able to infer that it holds.
* The for loop desugaring requires that `Seq<T>: IntoIterator`,
which is provable from the bounds declared on `Seq<T>`.
### Type-checking `main`
@ -97,7 +102,9 @@ flowchart TD
### Within the `type_of` query
The `type_of` query, when applied to an opaque type O, returns the hidden type. That hidden type is computed by combining the results from each constraining function within defining scope of O.
The `type_of` query, when applied to an opaque type O, returns the hidden type.
That hidden type is computed by combining the results from each constraining function
within defining scope of O.
```mermaid
flowchart TD
@ -164,7 +171,9 @@ flowchart TD
### Interactions with queries
When queries encounter a `opaque_ty_obligation`, they do not try to process them, but instead just store the constraints into the infcx.
When queries encounter a `opaque_ty_obligation`,
they do not try to process them,
but instead just store the constraints into the infcx.
```mermaid
graph TD
@ -184,9 +193,13 @@ graph TD
end
```
The registered hidden types are stored into the `QueryResponse` struct in the `opaque_types` field (the function `take_opaque_types_for_query_response` reads them out).
The registered hidden types are stored into the `QueryResponse` struct in
the `opaque_types` field
(the function `take_opaque_types_for_query_response` reads them out).
When the `QueryResponse` is instantiated into the surrounding infcx in `query_response_substitution_guess`, we convert each hidden type constraint by invoking `handle_opaque_type` (as above).
When the `QueryResponse` is instantiated into the surrounding infcx in
`query_response_substitution_guess`,
we convert each hidden type constraint by invoking `handle_opaque_type` (as above).
There is one bit of "weirdness".
The instantiated opaque types are stored in a *map*,