Unused variables, better as error or warning?

[Walter Bright]

bearophile wrote:
> Walter Bright:
>> Not every problem is worth using a sledgehammer to deal with.
> Giving a warning where you have not used a variable is not a sledgehammer,
> it's a light thing, that helps keep code tidy and once in a while helps avoid
> bugs.

My point is it is not a light thing. It negatively and irritatingly impacts 
normal coding practices. Adding in pragmas uglifies the code. More compiler 
switches increases the cognitive load.

(I've seen many build scripts for C/C++ that include a long list of switches. I 
ask the developer what those switches do, he often has no idea. He just copied 
the list of switches from some other project.)

So it's a tradeoff. How much time do you save when it finds an actual bug, vs 
how much time it costs you to futz around trying to suppress invalid warnings.