Struct rustc_trait_selection::solve::search_graph::overflow::OverflowData

pub(super) struct OverflowData {
    default_limit: Limit,
    current_limit: Limit,
    additional_depth: usize,
}

When detecting a solver overflow, we return ambiguity. Overflow can be hidden by either a fatal error in an AND or a trivial success in an OR.

This is in issue in case of exponential blowup, e.g. if each goal on the stack has multiple nested (overflowing) candidates. To deal with this, we reduce the limit used by the solver when hitting the default limit for the first time.

FIXME: Get tests where always using the default_limit results in a hang and refer to them here. We can also improve the overflow strategy if necessary.

Fields

default_limit: Limit

current_limit: Limit

additional_depth: usize

When proving an AND we have to repeatedly iterate over the yet unproven goals.

Because of this each iteration also increases the depth in addition to the stack depth.

Implementations

impl OverflowData

pub(super) fn new(tcx: TyCtxt<'_>) -> OverflowData

pub(super) fn did_overflow(&self) -> bool

pub(super) fn has_overflow(&self, depth: usize) -> bool

fn deal_with_overflow(&mut self)

Updating the current limit when hitting overflow.

Layout

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain repr(...) attributes. Please see the Rust Reference’s “Type Layout” chapter for details on type layout guarantees.

Size:24 bytes