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Rollup merge of #95646 - mgeisler:mention-std-env-var, r=Dylan-DPC

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Mention `std::env::var` in `env!`

When searching for how to read an environment variable, I first encountered the `env!` macro. It would have been useful to me if the documentation had included a link to `std::env::var`, which is what I was actually looking for.
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Dylan DPC 2022-04-07 06:04:52 +02:00 committed by GitHub
commit a2df05d4d5
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1 changed files with 8 additions and 2 deletions
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10
library/core/src/macros/mod.rs
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@ -909,7 +909,10 @@ pub(crate) mod builtin {
/// Inspects an environment variable at compile time.
///
/// This macro will expand to the value of the named environment variable at
/// compile time, yielding an expression of type `&'static str`.
/// compile time, yielding an expression of type `&'static str`. Use
/// [`std::env::var`] instead if you want to read the value at runtime.
///
/// [`std::env::var`]: ../std/env/fn.var.html
///
/// If the environment variable is not defined, then a compilation error
/// will be emitted. To not emit a compile error, use the [`option_env!`]
@ -950,7 +953,10 @@ pub(crate) mod builtin {
/// expand into an expression of type `Option<&'static str>` whose value is
/// `Some` of the value of the environment variable. If the environment
/// variable is not present, then this will expand to `None`. See
/// [`Option<T>`][Option] for more information on this type.
/// [`Option<T>`][Option] for more information on this type. Use
/// [`std::env::var`] instead if you want to read the value at runtime.
///
/// [`std::env::var`]: ../std/env/fn.var.html
///
/// A compile time error is never emitted when using this macro regardless
/// of whether the environment variable is present or not.