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Remove need for ResumeTy / get_context in async generators #104828

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Swatinem opened this issue Nov 24, 2022 · 0 comments · Fixed by #105250
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Remove need for ResumeTy / get_context in async generators #104828

Swatinem opened this issue Nov 24, 2022 · 0 comments · Fixed by #105250

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@Swatinem
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#104321 changed async blocks/functions to not go through from_generator / GenFuture, but made those generators implement Future directly.

Though inside those special generators, it is still necessary to hide the &Context<'_> poll argument behind an unsafe ResumeTy wrapper which removes any lifetime constraints.

It should be possible to remove that type, and the unsafe get_context function which turns it back into a &Context<'_> to poll child futures.

With #104321 the compiler already "cheats" and magically turns the &Context<'_> of the Future::poll call into an internal Generator::resume(ResumeTy).
This was referenced Nov 30, 2022
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matthiaskrgr added a commit to matthiaskrgr/rust that referenced this issue Dec 5, 2022
@matthiaskrgr
Rollup merge of rust-lang#105250 - Swatinem:async-rm-resumety, r=oli-obk
b684625 
Replace usage of `ResumeTy` in async lowering with `Context`

Replaces using `ResumeTy` / `get_context` in favor of using `&'static mut Context<'_>`.

Usage of the `'static` lifetime here is technically "cheating", and replaces the raw pointer in `ResumeTy` and the `get_context` fn that pulls the correct lifetimes out of thin air.

fixes rust-lang#104828 and rust-lang#104321 (comment)

r? `@oli-obk`
matthiaskrgr added a commit to matthiaskrgr/rust that referenced this issue Dec 5, 2022
@matthiaskrgr
Rollup merge of rust-lang#105250 - Swatinem:async-rm-resumety, r=oli-obk
3566eb4 
Replace usage of `ResumeTy` in async lowering with `Context`

Replaces using `ResumeTy` / `get_context` in favor of using `&'static mut Context<'_>`.

Usage of the `'static` lifetime here is technically "cheating", and replaces the raw pointer in `ResumeTy` and the `get_context` fn that pulls the correct lifetimes out of thin air.

fixes rust-lang#104828 and rust-lang#104321 (comment)

r? ``@oli-obk``
matthiaskrgr added a commit to matthiaskrgr/rust that referenced this issue Dec 5, 2022
@matthiaskrgr
Rollup merge of rust-lang#105250 - Swatinem:async-rm-resumety, r=oli-obk
90ccb17 
Replace usage of `ResumeTy` in async lowering with `Context`

Replaces using `ResumeTy` / `get_context` in favor of using `&'static mut Context<'_>`.

Usage of the `'static` lifetime here is technically "cheating", and replaces the raw pointer in `ResumeTy` and the `get_context` fn that pulls the correct lifetimes out of thin air.

fixes rust-lang#104828 and rust-lang#104321 (comment)

r? ```@oli-obk```
@bors bors closed this as completed in 967085e Dec 6, 2022
thomcc pushed a commit to tcdi/postgrestd that referenced this issue Feb 10, 2023
@matthiaskrgr
Rollup merge of #105250 - Swatinem:async-rm-resumety, r=oli-obk
43ed205 
Replace usage of `ResumeTy` in async lowering with `Context`

Replaces using `ResumeTy` / `get_context` in favor of using `&'static mut Context<'_>`.

Usage of the `'static` lifetime here is technically "cheating", and replaces the raw pointer in `ResumeTy` and the `get_context` fn that pulls the correct lifetimes out of thin air.

fixes rust-lang/rust#104828 and rust-lang/rust#104321 (comment)

r? `@oli-obk`
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Replace usage of ResumeTy in async lowering with Context Swatinem/rust
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@Swatinem