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Make function literal return type inference infer void from context #1092

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Jul 15, 2020
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Make function literal return type inference infer void from context #1092

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11 changes: 8 additions & 3 deletions resources/type-system/inference.md
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Expand Up @@ -6,6 +6,9 @@ Status: Draft

## CHANGELOG

2020.07.14:
- Infer return type `void` from context with function literals.

2020.06.04:
- Make conflict resolution for override inference explicit.

Expand Down Expand Up @@ -318,9 +321,11 @@ The **actual returned type** of the function literal is the value of `T` after
all `return` and `yield` statements in the block body have been considered.

Let `T` be the **actual returned type** of a function literal as computed above.
Let `R` be the greatest closure of the typing context `K` as computed above. If
`T <: R` then let `S` be `T`. Otherwise, let `S` be `R`. The inferred return
type of the function literal is then defined as follows:
Let `R` be the greatest closure of the typing context `K` as computed above.
If `R` is `void`, or the function literal is marked `async` and `R` is
`FutureOr<void>`, let `S` be `void`. Otherwise, if `T <: R` then let `S` be
`T`. Otherwise, let `S` be `R`. The inferred return type of the function
literal is then defined as follows:
- If the function literal is marked `async` then the inferred return type is
`Future<flatten(S)>`.
- If the function literal is marked `async*` then the inferred return type is
Expand Down