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Checking that they really do use thin pointers.
- Add some explanatory comments. - Rename `OpaqueListContents` as `ExternTy`. I've always found both the "opaque" and "contents" parts of this name to be confusing. Calling it `ExternTy` makes it clear that all that matters is it's an extern type.
- Merge the `List` and `ListWithCachedTypeInfo` impls by referring to the shared underlying type, `RawList`. This required increasing the visibility of `RawList`. - Explain why a separate impl is needed for `RawList`. - Remove an incorrect FIXME comment. Fat reference types will always need a separate impl. (To be sure, one could use `T: ?Sized` to merge the impls for `&T` and `&[T]` and it would compile but it would behave incorrectly because `&T` needs one word of storage and `&[T]` needs two words of storage. I tried it and it did not go well.)
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Works for me! @bors r+ |
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| // FIXME(#151565): Using `T: ?Sized` here should let us remove the separate | ||
| // impls for fat reference types. |
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Here I was thinking we could replace size_of::<&'_ ()>() with size_of::<&'_ T>() and just get the correct size automatically, but that appears to not actually work smoothly since it then complains about needing #![feature(generic_const_exprs)].
So removing this FIXME is probably the right call.
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Rollup of 5 pull requests Successful merges: - #152935 (c-variadic: error when we can't guarantee that the backend does the right thing) - #153207 (std::net: clamp linger timeout value to prevent silent truncation.) - #154592 (Fix `mismatched_lifetime_syntaxes` suggestions for hidden path lifetimes) - #154643 (fix pin docs) - #154648 (Clarify `ty::List`)
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ty::Listis an unusual type. This commit clarifies some things about it. Details in individual commits.r? @cuviper