Why doesn't DMD create any redundant symbols?

[Christopher Wright]

Frank Benoit wrote:
> Walter Bright schrieb:
>> Gregor Richards wrote:
>>> Walter Bright wrote:
>>>> Gregor Richards wrote:
>>>>> I have to assume there's a reason for this, so, to summarize: Why 
>>>>> doesn't DMD create any redundant symbols in .o files?
>>>>
>>>> It can improve build speed a lot. With C++, which doesn't do this, 
>>>> huge .obj files can be generated.
>>>>
>>>> The compiler assumes that if there are multiple modules on the 
>>>> command line, they'll all be linked together, so why generate 
>>>> redundant output?
>>>
>>> OK, so how about for those willing to (or required to) take the 
>>> performance penalty, adding an option to create redundant data? I 
>>> imagine the speed difference between compiling one file at a time and 
>>> compiling all at once but with redundant data is greater than the 
>>> speed difference between compiling all at once with and without 
>>> redundant data, so your improvement to build speed significantly 
>>> hinders my build speed.
>>
>> It's a good idea, but it would be a fair bit of work the way dmd is 
>> designed.
> 
> DSSS has the option oneatatime=on as the default now, to avoid problems. 
> But the compile time is no more acceptable.
> 
> Several ppl complained that after 15 min they canceled compilation of 
> DWT. With doing it with oneatatime=off the same took <15 sec.
> 
> See also http://d.puremagic.com/issues/show_bug.cgi?id=1838
> 

The problem being that, without those possibly redundant symbols, you 
get stuff dying at link time because DMD never bothered to include the 
symbol anywhere?

Performance is secondary to correctness.