Typo in 2024-09-05-impl-trait-capture-rules.md

TBoshoven · web-flow · commit 731332d880da · 2024-09-08T12:21:12.000-04:00
diff --git a/posts/2024-09-05-impl-trait-capture-rules.md b/posts/2024-09-05-impl-trait-capture-rules.md
@@ -102,7 +102,7 @@ fn process<'c, T> {
 }
 ```
 
-Here the `process` function applies `context.process` to each of the elements in `data` (of type `T`). Because the return value uses `context`, it is declared as `+ 'c`. Our real goal here is to allow the return type to use `'c`; writing `+ 'c` achieves that goal because `'c` not appears in the bound listing. However, while writing `+ 'c` is a convenient way to make `'c` appear in the bounds, also means that the hidden type must outlive `'c`. This requirement is not needed and will in fact lead to a compilation error in this example ([try it on the playground](https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=b742fbf9b083a6e837db0b170489f34a)).
+Here the `process` function applies `context.process` to each of the elements in `data` (of type `T`). Because the return value uses `context`, it is declared as `+ 'c`. Our real goal here is to allow the return type to use `'c`; writing `+ 'c` achieves that goal because `'c` now appears in the bound listing. However, while writing `+ 'c` is a convenient way to make `'c` appear in the bounds, also means that the hidden type must outlive `'c`. This requirement is not needed and will in fact lead to a compilation error in this example ([try it on the playground](https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=b742fbf9b083a6e837db0b170489f34a)).
 
 The reason that this error occurs is a bit subtle. The hidden type is an iterator type based on the result of `data.into_iter()`, which will include the type `T`. Because of the `+ 'c` bound, the hidden type must outlive `'c`, which in turn means that `T` must outlive `'c`. But `T` is a generic parameter, so the compiler requires a where-clause like `where T: 'c`. This where-clause means "it is safe to create a reference with lifetime `'c` to the type `T`". But in fact we don't create any such reference, so the where-clause should not be needed. It is only needed because used the convenient-but-sometimes-incorrect workaround of adding `+ 'c` to the bounds of our `impl Trait`.
 

Original file line number	Diff line number	Diff line change
`@@ -102,7 +102,7 @@ fn process<'c, T> {`
`102`	`102`	`}`
`103`	`103`	```
`104`	`104`
`105`		-Here the `process` function applies `context.process` to each of the elements in `data` (of type `T`). Because the return value uses `context`, it is declared as `+ 'c`. Our real goal here is to allow the return type to use `'c`; writing `+ 'c` achieves that goal because `'c` not appears in the bound listing. However, while writing `+ 'c` is a convenient way to make `'c` appear in the bounds, also means that the hidden type must outlive `'c`. This requirement is not needed and will in fact lead to a compilation error in this example ([try it on the playground](https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=b742fbf9b083a6e837db0b170489f34a)).
	`105`	+Here the `process` function applies `context.process` to each of the elements in `data` (of type `T`). Because the return value uses `context`, it is declared as `+ 'c`. Our real goal here is to allow the return type to use `'c`; writing `+ 'c` achieves that goal because `'c` now appears in the bound listing. However, while writing `+ 'c` is a convenient way to make `'c` appear in the bounds, also means that the hidden type must outlive `'c`. This requirement is not needed and will in fact lead to a compilation error in this example ([try it on the playground](https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=b742fbf9b083a6e837db0b170489f34a)).
`106`	`106`
`107`	`107`	The reason that this error occurs is a bit subtle. The hidden type is an iterator type based on the result of `data.into_iter()`, which will include the type `T`. Because of the `+ 'c` bound, the hidden type must outlive `'c`, which in turn means that `T` must outlive `'c`. But `T` is a generic parameter, so the compiler requires a where-clause like `where T: 'c`. This where-clause means "it is safe to create a reference with lifetime `'c` to the type `T`". But in fact we don't create any such reference, so the where-clause should not be needed. It is only needed because used the convenient-but-sometimes-incorrect workaround of adding `+ 'c` to the bounds of our `impl Trait`.
`108`	`108`