Expand description
The Rust Core Library
The Rust Core Library is the dependency-free1 foundation of The Rust Standard Library. It is the portable glue between the language and its libraries, defining the intrinsic and primitive building blocks of all Rust code. It links to no upstream libraries, no system libraries, and no libc.
The core library is minimal: it isn’t even aware of heap allocation, nor does it provide concurrency or I/O. These things require platform integration, and this library is platform-agnostic.
How to use the core library
Please note that all of these details are currently not considered stable.
This library is built on the assumption of a few existing symbols:
-
memcpy
,memcmp
,memset
,strlen
- These are core memory routines which are often generated by LLVM. Additionally, this library can make explicit calls to these functions. Their signatures are the same as found in C. These functions are often provided by the system libc, but can also be provided by the compiler-builtins crate. -
rust_begin_panic
- This function takes four arguments, afmt::Arguments
, a&'static str
, and twou32
’s. These four arguments dictate the panic message, the file at which panic was invoked, and the line and column inside the file. It is up to consumers of this core library to define this panic function; it is only required to never return. This requires alang
attribute namedpanic_impl
. -
rust_eh_personality
- is used by the failure mechanisms of the compiler. This is often mapped to GCC’s personality function, but crates which do not trigger a panic can be assured that this function is never called. Thelang
attribute is calledeh_personality
.
Strictly speaking, there are some symbols which are needed but they aren’t always necessary. ↩
Primitive Types
!
type, also called “never”.[T; N]
, for the element type, T
, and the
non-negative compile-time constant size, N
.fn(usize) -> bool
.*const T
, and *mut T
.&T
and &mut T
.[T]
. Contiguous here
means that elements are laid out so that every element is the same
distance from its neighbors.(T, U, ..)
.()
type, also called “unit”.Modules
assert_matches
macro.char
primitive type.Clone
trait for types that cannot be ‘implicitly copied’.Default
trait for types with a default value.f32
single-precision floating point type.f64
double-precision floating point type.Result
type.Macros
format_args
, but can be used in some const contexts.format_args
, but adds a newline in the end.true
at runtime.true
at runtime.