When compiling multiple source files

[ProgrammingGhost]

On Monday, 19 August 2013 at 17:35:39 UTC, John Colvin wrote:
> On Monday, 19 August 2013 at 17:15:35 UTC, ProgrammingGhost 
> wrote:
>> On Monday, 19 August 2013 at 11:01:54 UTC, Jacob Carlborg 
>> wrote:
>>> The compiler will start compiling the files passed on the 
>>> command line. It will read the files asynchronously and then 
>>> lex, parse build an AST and do semantic analyze.
>>>
>>> When the semantic analyze is done it will have access to all 
>>> import declarations. It basically starts the same processes 
>>> for all these imports, recursively.
>>>
>>> The reason for waiting until semantic analyze is done because 
>>> you can have code looking like this:
>>>
>>> mixin("import foo;");
>>>
>>> The expansion of the mixin and other similar features are 
>>> done in the semantic analyze phase.
>>
>> So everything is parsed once and kept in memory until the 
>> compiler finish every source file? Is there any ram problems 
>> when compiling large codebases?
>
> Unfortunately, yes, if you give dmd a very large number of 
> files all at once, it will chew through all your free RAM. But 
> dmd does support separate compilation:
>
> $dmd file1.d -c
> $dmd file2.d -c
> $dmd file1.o file2.o
>
> which alleviates the problem.
>
>> My experience with D is limited. Are libraries the same as C 
>> libraries? From my understanding the linker figures that part 
>> out and the compiler needs a separate file for the definition. 
>> If I build a library in D is it the same as a C library or 
>> different which includes function definitions?
>>
>> Sorry if I'm confused I know almost nothing about D. I stick 
>> to .NET, java and C++
>
> Libraries in D use the same formats as C/C++ libraries.

Is it possible that if I just try to compile 1 file it could 
imports enough libraries that import/need the definitions for 
additional large libraries which in turn also imports everything 
causing ram issues? I'm sure in practice this will almost never 
happen. But I don't doubt there are main libraries that use other 
large libraries and everything imports/uses everything