Unused variables and bugs

[Brendan Zabarauskas via Digitalmars-d]

I use Rust a reasonable amount, and the 'unused variable', 
'unused field' and 'unused item' family of lints help a great 
deal in picking up mistakes early, especially when refactoring. 
Don't ask me to cite specific examples though - because they are 
enabled by default the issues are usually picked up and addressed 
early.

Note that in order not to make the the lint more bearable, 
underscore-prefixed identifiers are ignored and you can also 
disable any lint can be disabled on an item-by-item basis using 
an attribute (although in practice the latter option is rarely 
used). I do think without those options it would be a massive 
pain. The underscore thing might not be an option for D though - 
do preceding underscores have a specific meaning in the 
prevailing D coding style?