Module rustc_const_eval::transform::promote_consts

A pass that promotes borrows of constant rvalues.

The rvalues considered constant are trees of temps, each with exactly one initialization, and holding a constant value with no interior mutability. They are placed into a new MIR constant body in promoted and the borrow rvalue is replaced with a Literal::Promoted using the index into promoted of that constant MIR.

This pass assumes that every use is dominated by an initialization and can otherwise silence errors, if move analysis runs after promotion on broken MIR.

Structs

Candidate

A “root candidate” for promotion, which will become the returned value in a promoted MIR, unless it’s a subset of a larger candidate.

Collector 🔒

PromoteTemps

A MirPass for promotion.

Promoter 🔒

Unpromotable 🔒

Validator 🔒

Checks whether locals that appear in a promotion context (Candidate) are actually promotable.

Enums

TempState

State of a temporary during collection and promotion.

Functions

collect_temps_and_candidates

is_const_fn_in_array_repeat_expression

This function returns true if the function being called in the array repeat expression is a const function.

promote_candidates

validate_candidates