Why does MLint issue an inappropriate 'might be growing inside a loop' warning?

The MLint shows a 'might be growing inside a loop' warning when a finite string is concatenated with each line of a file when a loop is used to access the file line by line.

For example, if you type in the following

function lint_2007jul18(fIn, fOut)

while true

tline = fgets(fIn);

if tline == -1, break; end

if ~isempty(strfind(tline,'skip'))

tline = [ '%<skip> ' tline ];

end

fwrite(fOut,'%s', tline);

end

end

MLint shows a warning 'might be growing inside a loop'.

Answer 1

[MathWorks Support Team]

This is a known issue. Mlint runs a test to see if the variable is growing but its result is not guaranteed, which is why the warning says 'might be growing', not 'is growing'.