DMD Source Guidance: Unused Return Values of Strictly Pure Function Calls

[Timon Gehr]

On 02/28/2014 12:38 AM, "Nordlöw" wrote:
> Does anybody know where in the DMD source I can figure out if the return
> value of a function call is used or not?

I'm not familiar with the DMD source code, but a good way to proceed is 
usually to grep for existing error messages that are somehow related. In 
this case, DMD already complains about some cases of unused values:

$ grep "no effect" *.c
declaration.c:       error("storage class 'auto' has no effect if type 
is not inferred, did you mean 'scope'?");
expression.c:            e = new CastExp(loc, e, Type::tvoid);   // 
avoid "has no effect" error
mtype.c:        // substitution has no effect on function pointer type.
sideeffect.c:                     * Don't complain about an expression 
with no effect if it was cast to void
sideeffect.c:                /* Don't complain about calling functions 
with no effect,
sideeffect.c:                error("%s has no effect", toChars());
sideeffect.c:                error("%s has no effect in expression (%s)",

This leads directly to sideeffect.c: Expression::discardValue(), which 
seems to be the place where you want to insert your detection code.