Crate core

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 - 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 rlibc crate.

• rust_begin_panic - This function takes three arguments, a fmt::Arguments, a &'static str, and a u32. These three arguments dictate the panic message, the file at which panic was invoked, and the line. It is up to consumers of this core library to define this panic function; it is only required to never return. This requires a lang attribute named panic_fmt.

---

1. Strictly speaking, there are some symbols which are needed but they aren't always necessary. ↩

Modules

any	This module implements the Any trait, which enables dynamic typing of any 'static type through runtime reflection.
borrow	A module for working with borrowed data.
cell	Shareable mutable containers.
char	Character manipulation.
clone	The Clone trait for types that cannot be 'implicitly copied'.
cmp	Functionality for ordering and comparison.
convert	Traits for conversions between types.
default	The Default trait for types which may have meaningful default values.
f32	Operations and constants for 32-bits floats (f32 type)
f64	Operations and constants for 64-bits floats (f64 type)
fmt	Utilities for formatting and printing strings.
hash	Generic hashing support.
i16	The 16-bit signed integer type.
i32	The 32-bit signed integer type.
i64	The 64-bit signed integer type.
i8	The 8-bit signed integer type.
isize	The pointer-sized signed integer type.
iter	Composable external iteration.
marker	Primitive traits and marker types representing basic 'kinds' of types.
mem	Basic functions for dealing with memory.
num	Numeric traits and functions for the built-in numeric types.
ops	Overloadable operators.
option	Optional values.
prelude	The libcore prelude
ptr	Raw, unsafe pointers, *const T, and *mut T.
result	Error handling with the Result type.
slice	Slice management and manipulation
str	String manipulation
sync	Synchronization primitives
u16	The 16-bit unsigned integer type.
u32	The 32-bit unsigned integer type.
u64	The 64-bit unsigned integer type.
u8	The 8-bit unsigned integer type.
usize	The pointer-sized unsigned integer type.
array	[Unstable] Implementations of things like Eq for fixed-length arrays up to a certain length. Eventually we should able to generalize to all lengths.
intrinsics	[Unstable] rustc compiler intrinsics.
nonzero	[Unstable] Exposes the NonZero lang item which provides optimization hints.
panicking	[Unstable] Panic support for libcore
raw	[Unstable] Contains struct definitions for the layout of compiler built-in types.

Macros

assert!	Ensure that a boolean expression is true at runtime.
assert_eq!	Asserts that two expressions are equal to each other.
debug_assert!	Ensure that a boolean expression is true at runtime.
debug_assert_eq!	Asserts that two expressions are equal to each other.
panic!	Entry point of thread panic, for details, see std::macros
try!	Helper macro for unwrapping Result values while returning early with an error if the value of the expression is Err. Can only be used in functions that return Result because of the early return of Err that it provides.
unimplemented!	A standardized placeholder for marking unfinished code. It panics with the message "not yet implemented" when executed.
unreachable!	A utility macro for indicating unreachable code.
write!	Use the format! syntax to write data into a buffer.
writeln!	Use the format! syntax to write data into a buffer, appending a newline. On all platforms, the newline is the LINE FEED character (\n/U+000A) alone (no additional CARRIAGE RETURN (\r/U+000D).