rust/tests/rustdoc/synthetic_auto/no-redundancy.rs

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Generate documentation for auto-trait impls A new section is added to both both struct and trait doc pages. On struct/enum pages, a new 'Auto Trait Implementations' section displays any synthetic implementations for auto traits. Currently, this is only done for Send and Sync. On trait pages, a new 'Auto Implementors' section displays all types which automatically implement the trait. Effectively, this is a list of all public types in the standard library. Synthesized impls for a particular auto trait ('synthetic impls') take into account generic bounds. For example, a type 'struct Foo<T>(T)' will have 'impl<T> Send for Foo<T> where T: Send' generated for it. Manual implementations of auto traits are also taken into account. If we have the following types: 'struct Foo<T>(T)' 'struct Wrapper<T>(Foo<T>)' 'unsafe impl<T> Send for Wrapper<T>' // pretend that Wrapper<T> makes this sound somehow Then Wrapper will have the following impl generated: 'impl<T> Send for Wrapper<T>' reflecting the fact that 'T: Send' need not hold for 'Wrapper<T>: Send' to hold Lifetimes, HRTBS, and projections (e.g. '<T as Iterator>::Item') are taken into account by synthetic impls However, if a type can *never* implement a particular auto trait (e.g. 'struct MyStruct<T>(*const T)'), then a negative impl will be generated (in this case, 'impl<T> !Send for MyStruct<T>') All of this means that a user should be able to copy-paste a synthetic impl into their code, without any observable changes in behavior (assuming the rest of the program remains unchanged).
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pub struct Inner<T> {
field: T,
}
unsafe impl<T> Send for Inner<T>
where
T: Copy + Send,
{
}
// @has no_redundancy/struct.Outer.html
// @has - '//*[@id="synthetic-implementations-list"]//*[@class="impl"]//h3[@class="code-header"]' \
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// "impl<T> Send for Outer<T>where T: Send + Copy"
Generate documentation for auto-trait impls A new section is added to both both struct and trait doc pages. On struct/enum pages, a new 'Auto Trait Implementations' section displays any synthetic implementations for auto traits. Currently, this is only done for Send and Sync. On trait pages, a new 'Auto Implementors' section displays all types which automatically implement the trait. Effectively, this is a list of all public types in the standard library. Synthesized impls for a particular auto trait ('synthetic impls') take into account generic bounds. For example, a type 'struct Foo<T>(T)' will have 'impl<T> Send for Foo<T> where T: Send' generated for it. Manual implementations of auto traits are also taken into account. If we have the following types: 'struct Foo<T>(T)' 'struct Wrapper<T>(Foo<T>)' 'unsafe impl<T> Send for Wrapper<T>' // pretend that Wrapper<T> makes this sound somehow Then Wrapper will have the following impl generated: 'impl<T> Send for Wrapper<T>' reflecting the fact that 'T: Send' need not hold for 'Wrapper<T>: Send' to hold Lifetimes, HRTBS, and projections (e.g. '<T as Iterator>::Item') are taken into account by synthetic impls However, if a type can *never* implement a particular auto trait (e.g. 'struct MyStruct<T>(*const T)'), then a negative impl will be generated (in this case, 'impl<T> !Send for MyStruct<T>') All of this means that a user should be able to copy-paste a synthetic impl into their code, without any observable changes in behavior (assuming the rest of the program remains unchanged).
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pub struct Outer<T> {
inner_field: Inner<T>,
}