What about unused variables?

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swestin
Posts: 8
Joined: Wed May 28, 2014 6:53 pm
Company: GrammaTech Inc.

What about unused variables?

Post by swestin » Fri Jul 18, 2014 2:51 pm

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

misra-c
Posts: 548
Joined: Thu Jan 05, 2006 1:11 pm

Re: What about unused variables?

Post by misra-c » Fri Aug 22, 2014 12:30 pm

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.
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Posted by and on behalf of
the MISRA C Working Group

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