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Add known issue of let binding to format_args doc #111106

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Feb 15, 2024
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Add known issue of let binding to format_args doc #111106

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8 changes: 8 additions & 0 deletions library/core/src/macros/mod.rs
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Expand Up @@ -868,6 +868,14 @@ pub(crate) mod builtin {
/// let s = fmt::format(format_args!("hello {}", "world"));
/// assert_eq!(s, format!("hello {}", "world"));
/// ```
///
/// # Lifetime limitation
///
/// Except when no formatting arguments are used,
/// the produced `fmt::Arguments` value borrows temporary values,
/// which means it can only be used within the same expression
/// and cannot be stored for later use.
/// This is a known limitation, see [#92698](https://github.com/rust-lang/rust/issues/92698).
#[stable(feature = "rust1", since = "1.0.0")]
#[cfg_attr(not(test), rustc_diagnostic_item = "format_args_macro")]
#[allow_internal_unsafe]
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