Method TypeCheck

postgres/parser/sem/tree/type_check.go:658–699

TypeCheck implements the Expr interface.

(
	ctx context.Context, semaCtx *SemaContext, desired *types.T,
)

// TypeCheck implements the Expr interface.
func (expr *ComparisonExpr) TypeCheck(
	ctx context.Context, semaCtx *SemaContext, desired *types.T,
) (TypedExpr, error) {
	var leftTyped, rightTyped TypedExpr
	var cmpOp *CmpOp
	var alwaysNull bool
	var err error
	if expr.Operator.HasSubOperator() {
		leftTyped, rightTyped, cmpOp, alwaysNull, err = typeCheckComparisonOpWithSubOperator(
			ctx,
			semaCtx,
			expr.Operator,
			expr.SubOperator,
			expr.Left,
			expr.Right,
		)
	} else {
		leftTyped, rightTyped, cmpOp, alwaysNull, err = typeCheckComparisonOp(
			ctx,
			semaCtx,
			expr.Operator,
			expr.Left,
			expr.Right,
		)
	}
	if err != nil {
		return nil, err
	}

	if alwaysNull {
		return DNull, nil
	}

	if err := semaCtx.checkVolatility(cmpOp.Volatility); err != nil {
		return nil, pgerror.Wrapf(err, pgcode.InvalidParameterValue, "%s", expr.Operator)
	}

	expr.Left, expr.Right = leftTyped, rightTyped
	expr.Fn = cmpOp
	expr.typ = types.Bool
	return expr, nil
}

var (
	errStarNotAllowed      = pgerror.New(pgcode.Syntax, "cannot use \"*\" in this context")