Why does the Code Analyzer flag this as an error?

Why does the Code Analyzer flag this code as an error? It runs fine:

try
    error("It's bad")
catch ME
  warning('Error in code: %s', ME.message);
end

Warning: Error in code: It's bad

Answer 1

[Matt J]

Mathworks Support has classified it as a bug.

[dpb]

That's pretty-much what my conclusion was although I said mlint was too picky... :)

Answer 2

[dpb]

Having warning() inside the catch clause is the problem -- the catch clause is executed only when an error condition exists and mixing that up with trying to issue a warning is sorta' like double jeopardy and mlint doesn't like it...

Just output any additional message with disp or fprintf, don't try to throw a warning there...

try
    error("It's bad")
catch ME
  fprintf('Error in code: \n%s\n',ME.message);
end

shows no error or warning.

[Matt J]

That does make a certain amount of sense, but the explanation given by the Code Analyzer doesn't resemble that:

[dpb]

Yeah, @Matt J, I thought about addressing that but decided to not touch it. :)

The suggested solution doesn't work(*) when the warning is inside the catch block, either...I believe the authors of mlint never thought of nor tested the case.

It's probably worth an enhancement/bug report...

(*) Actually, on further exploration using the other format string argument does convert the mlint error into a warning although it may take moving around in the file some first before the red line is replaced by the orange one. You then get a warning that the number of output items may not match the format specification. Either way, there isn't an actual syntax error in the warning statement per se, just a picky mlint false positive, I think.