More inference-friendly API for lazy #103718
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The signature for new was ``` fn new<F>(f: F) -> Lazy<T, F> ``` Notably, with `F` unconstrained, `T` can be literally anything, and just `let _ = Lazy::new(|| 92)` would not typecheck. This historiacally was a necessity -- `new` is a `const` function, it couldn't have any bounds. Today though, we can move `new` under the `F: FnOnce() -> T` bound, which gives the compiler enough data to infer the type of T from closure.
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…mpiler-errors Rollup of 9 pull requests Successful merges: - rust-lang#103718 (More inference-friendly API for lazy) - rust-lang#105765 (Detect likely `.` -> `..` typo in method calls) - rust-lang#105852 (Suggest rewriting a malformed hex literal if we expect a float) - rust-lang#105965 (Provide local extern function arg names) - rust-lang#106064 (Partially fix `explicit_outlives_requirements` lint in macros) - rust-lang#106179 (Fix a formatting error in Iterator::for_each docs) - rust-lang#106181 (Fix doc comment parsing description in book) - rust-lang#106187 (Update the documentation of `Vec` to use `extend(array)` instead of `extend(array.iter().copied())`) - rust-lang#106189 (Fix UnsafeCell Documentation Spelling Error) Failed merges: r? `@ghost` `@rustbot` modify labels: rollup
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The signature for new was
Notably, with
Funconstrained,Tcan be literally anything, and justlet _ = Lazy::new(|| 92)would not typecheck.This historiacally was a necessity --
newis aconstfunction, it couldn't have any bounds. Today though, we can movenewunder theF: FnOnce() -> Tbound, which gives the compiler enough data to infer the type of T from closure.