Function commonConstantType

pkg/sql/sem/tree/constant.go:379–395

commonConstantType returns the most constrained type which is mutually resolvable between a set of provided constants. The function takes a slice of Exprs and indexes, but expects all the indexed Exprs to wrap a Constant. The reason it does no take a slice of Constants instead is to avoid forcing c

(vals []Expr, idxs []int)

// Exprs to wrap a Constant. The reason it does no take a slice of Constants
// instead is to avoid forcing callers to allocate separate slices of Constant.
func commonConstantType(vals []Expr, idxs []int) (*types.T, bool) {
	var candidates []*types.T

	for _, i := range idxs {
		availableTypes := vals[i].(Constant).DesirableTypes()
		if candidates == nil {
			candidates = availableTypes
		} else {
			candidates = intersectTypeSlices(candidates, availableTypes)
		}
	}

	if len(candidates) > 0 {
		return candidates[0], true
	}
	return nil, false
}

// StrVal represents a constant string value.
type StrVal struct {