Unused variables and bugs

[bearophile via Digitalmars-d]

Apparently there is evidence that unused variables in C-like 
languages correlate with bugs:

https://kev.inburke.com/slides/errors/#error-correlations

One problem with ruling out some classes of unused variables 
(like unused function arguments, unused private module-level 
variables, unused function-local variables, and so on) is that 
when you are writing code you sometimes add some unused 
variables, that you usually will use or remove later.

So you usually don't want an error or warning for unused 
variables when you are writing code, but later there is a moment 
when you probably want to clean up your code and remove any 
unused variable to make the code more clean and tight.

A simple solution in C-languages is to add a compiler switch that 
allows to disallow or allow the unused variables according to the 
phase of your working on the code. But compiler switch 
proliferation can be a problem (unless you use an IDE, that 
offers you a button to enable/disable such tests).

Another solution is to leave such tests out of the core compiler, 
and put them in a lint tool that you run when you think your code 
is in good shape.

Bye,
bearophile