Struct ImplicitPrecedence

pub struct ImplicitPrecedence(/* private fields */);

Extra information about sorting of implicit arguments of the function.

In most of the user written code, the implicits are not stated explicitly, but instead are inferred by the compiler. The order on how these implicit arguments are laid out on Sierra level is unspecified though for the users. Currently, the compiler sorts them alphabetically by name for reproducibility, but it can equally just randomize the order on each compilation.

Some compilation targets tend to expect that particular functions accept particular implicit arguments at fixed positions. For example, the Starknet OS has such assumptions. By reading the implicit precedence information attached to functions, the compiler can now reliably generate compatible code.

To set, add the #[implicit_precedence(...)] attribute to function declaration. Only free or impl functions can have this information defined. For extern functions, the compiler raises an error. It is recommended to always create this attribute from compiler plugins, and not force users to write it manually.

Use ImplicitPrecedence::UNSPECIFIED to represent lack of information.

Implementations

impl ImplicitPrecedence

pub const UNSPECIFIED: Self = _

A precedence that does not actually prefer any implicit.

When applied to a sequence of implicits, they will just be reordered alphabetically.

pub fn apply(&self, implicits: &mut [TypeId], db: &dyn SemanticGroup)

Sort implicits according to this precedence: first the ones with precedence (according to it), then the others by their name.

Trait Implementations

impl Clone for ImplicitPrecedence

fn clone(&self) -> ImplicitPrecedence

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for ImplicitPrecedence

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for ImplicitPrecedence

fn default() -> ImplicitPrecedence

Returns the “default value” for a type.

impl FromIterator<TypeId> for ImplicitPrecedence

fn from_iter<T: IntoIterator<Item = TypeId>>(iter: T) -> Self

Creates a value from an iterator.

impl PartialEq for ImplicitPrecedence

fn eq(&self, other: &ImplicitPrecedence) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Eq for ImplicitPrecedence

impl StructuralPartialEq for ImplicitPrecedence