Enum rustc_trait_selection::infer::region_constraints::Constraint

pub enum Constraint<'tcx> {
    VarSubVar(RegionVid, RegionVid),
    RegSubVar(Region<'tcx>, RegionVid),
    VarSubReg(RegionVid, Region<'tcx>),
    RegSubReg(Region<'tcx>, Region<'tcx>),
}

Represents a constraint that influences the inference process.

Variants

VarSubVar(RegionVid, RegionVid)

A region variable is a subregion of another.

RegSubVar(Region<'tcx>, RegionVid)

A concrete region is a subregion of region variable.

VarSubReg(RegionVid, Region<'tcx>)

A region variable is a subregion of a concrete region. This does not directly affect inference, but instead is checked after inference is complete.

RegSubReg(Region<'tcx>, Region<'tcx>)

A constraint where neither side is a variable. This does not directly affect inference, but instead is checked after inference is complete.

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

Size for each variant:

• VarSubVar: 8 bytes
• RegSubVar: 12 bytes
• VarSubReg: 12 bytes
• RegSubReg: 20 bytes