if sig == nil {
		check.errorf(x, InvalidCall, invalidOp+"cannot call non-function %s", x)
		x.mode = invalid
		x.expr = call
		return statement
	}

	// Capture wasGeneric before sig is potentially instantiated below.
	wasGeneric := sig.TypeParams().Len() > 0

	// evaluate type arguments, if any
	var xlist []syntax.Expr
	var targs []Type
	if inst != nil {
		xlist = syntax.UnpackListExpr(inst.Index)

	if sig == nil {
		check.errorf(x, InvalidCall, invalidOp+"cannot call non-function %s", x)
		x.mode = invalid
		x.expr = call
		return statement
	}

	// Capture wasGeneric before sig is potentially instantiated below.
	wasGeneric := sig.TypeParams().Len() > 0

	// evaluate type arguments, if any
	var xlist []ast.Expr
	var targs []Type
	if ix != nil {
		xlist = ix.Indices
		targs = check.typeList(xlist)