[fpc-pascal] Compiler option to check return value ignorance

[Jeff Wormsley]

Vinzent Höfler wrote:
> I just grep'ped the actual sources of the project (about 70K LOC) and 
> I found exactly four occurences of my "if Ignore_Result() then 
> {null};" pattern with FPC runtime routines. There are others, but 
> those routines access hardware and on some occasions I really need to 
> ignore failures there.
>
> 2x IOResult
> 1x SysUtils.DeleteFile
> 1x BaseUnix.fpChMod
>
> Twice more of this pattern occured to avoid the compiler hint of 
> unused parameters. So if "false positives" is an indicator for 
> uselessness of a compiler message, I'd tend to doubt the usefulness of 
> that.
So, if I read you correctly, if you call a function that you don't care 
what the result is, instead of:

Begin
  SomeFunction(123); // Ignore result
End;

... you would have us write:

Var Dummy: SomeType;
Begin
  Dummy := SomeFunction(123);
End;

... or else get warnings from the compiler?

I'm afraid there are tons of code out there that this would effect.  I 
don't think any of the maintainers of such code would appreciate that 
change much.  Maybe, just maybe, an optional {$MODE 
ULTRA_STRICT_FUNCTION_RESULT_USE} type compiler option, whose default 
was off, would be ok, but otherwise such a change would be far worse 
than the "problem" you are trying to address (someone improperly not 
using the function result when they were supposed to).

Jeff.

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