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VaArgSafe

std::ffi

Trait VaArgSafe 

Source 
pub unsafe trait VaArgSafe: Copy { }
ⓘ This trait cannot be implemented outside core.
🔬This is a nightly-only experimental API. (c_variadic #44930)
Expand description

Types that are valid to read using VaList::next_arg.

This trait is implemented for primitive types that have a variable argument application-binary interface (ABI) on the current platform. It is always implemented for:

Implementations for e.g. i32 or usize shouldn’t be relied upon directly, because they may not be available on all platforms.

§Safety

When C passes variable arguments, signed integers smaller than c_int are promoted to c_int, unsigned integers smaller than c_uint are promoted to c_uint, and c_float is promoted to c_double. Implementing this trait for types that are subject to this promotion rule is invalid.

This trait is only implemented for 128-bit integers when the platform defines the __int128 type.

Dyn Compatibility§

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors§