Starting with MATLAB R2023a, the behavior of indexing with no subscripts remains the same and does not error, but the warning no longer appears. Using the warning command to turn the warning on or off has no effect. For more information, see the linked MATLAB release note:
The source of a warning with the structure is code that uses indexing into variables with empty parentheses. This warning message is 'off' by default. In MATLAB R2017b, you can reproduce this warning by turning the warning on and indexing into an array without a subscript.
>> a = zeros(1, 3);
>> warning("on", "MATLAB:subscripting:noSubscriptsSpecified")
>> a()
Warning: A value of class "double" was indexed with no subscripts specified. Currently the result of this operation is the indexed value itself, but in a future release, it will
be an error.
ans =
0 0 0
If you are using MATLAB R2022b or earlier releases, you can turn off this warning. Execute this command in MATLAB to turn off the warning:
>> warning("off","MATLAB:subscripting:noSubscriptsSpecified");
