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+--- Forum: MISRA C:2012 and MISRA C:2023 guidelines (https://forum.misra.org.uk/forumdisplay.php?fid=21)
+---- Forum: 8.2 Unused code (https://forum.misra.org.uk/forumdisplay.php?fid=157)
+---- Thread: What about unused variables? (/showthread.php?tid=1080)
What about unused variables? - swestin - 18-07-2014
The guidelines proscribe declaring unused types, tags on structures or enums, macros, or labels.
Shouldn't there be a prohibition of undeclared variables, too?
-Stephen H. Westin
Re: What about unused variables? - misra-c - 22-08-2014
We are assuming that the question is intended to read "Shouldn't there be a prohibition of unused variables, too?"
Rule 2.7 covers variables that are declared as parameters to functions.
MISRA C:2012 permits other variables to be initialised and not used. However, if a variable is assigned a value, which is not used, then dead code will exist and rule 2.2 will be violated.
Unused initialisations are permitted because a common programming style is to use configuration files and conditional compilation. This can lead in some configurations to some variables being initialised but never used.
RE: What about unused variables? - misra-c - 01-07-2024
A new Rule 2.8 "A project should not contain unused object definitions" was added by MISRA C:2012 Amendment 4
Thanks for the suggestion