On 02/16/2018 12:43 PM, Daniel Colascione wrote:
> IMHO, we should enable -Wconversion more broadly.

My experience is just the opposite: i.e., that -Wconversion causes more 
trouble than it cures. The pdumper change to INTEGER_TO_CONS is an 
example of trouble. The only reason for that change is to work around a 
compiler bug in GCC that is caused by -Wconversion, a bug that leads to 
a false alarm. I suggest at least the attached patch, which limits the 
damage to pdumper.c instead of letting it spread to other Emacs modules. 
But better yet, I suggest dropping the idea of using -Wconversion even 
on pdumper.c, as it's counterproductive and in high-quality code almost 
inevitably leads to further obfuscation like ALLOW_IMPLICIT_CONVERSION 
and DISALLOW_IMPLICIT_CONVERSION.

PS. Double-parens like that shouldn't be needed in macro bodies, as each 
macro must parenthesize its argument properly anyway.