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Update no_builtins to use the attribute template #1909

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Update no_builtins to use the attribute template #1909

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241c383
Unwrap no_builtins
ehuss Jun 3, 2025
c7788ac
Update no_builtins to use attribute template
ehuss Jun 3, 2025
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24 changes: 21 additions & 3 deletions src/attributes/codegen.md
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Expand Up @@ -85,9 +85,27 @@ The [testing attributes](testing.md) cannot be applied to a naked function.
r[attributes.codegen.no_builtins]
## The `no_builtins` attribute

The *`no_builtins` [attribute]* may be applied at the crate level to disable
optimizing certain code patterns to invocations of library functions that are
assumed to exist.
r[attributes.codegen.no_builtins.intro]
The *`no_builtins` [attribute]* disables optimizing certain code patterns to invocations of library functions that are assumed to exist.

<!-- TODO: This needs expanding, see https://github.com/rust-lang/reference/issues/542 -->

> [!EXAMPLE]
> ```rust
> #![no_builtins]
> ```

r[attributes.codegen.no_builtins.syntax]
The `no_builtins` attribute uses the [MetaWord] syntax and thus does not take any inputs.

r[attributes.codegen.no_builtins.allowed-positions]
The `no_builtins` attribute can only be applied to the crate root.

r[attributes.codegen.no_builtins.duplicates]
Duplicate instances of the `no_builtins` attribute have no effect.

> [!NOTE]
> `rustc` currently warns on subsequent duplicate `no_builtins` attributes.

r[attributes.codegen.target_feature]
## The `target_feature` attribute
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