Please integrate build framework into the compiler

[grauzone]

dsimcha wrote:
> == Quote from grauzone (none at example.net)'s article
>> I claim that we don't even need incremental compilation. It would be
>> better if the compiler would scan for dependencies, and if a source file
>> has changed, recompile the whole project in one go. This would be simple
>> and efficient.
> 
> I'm surprised that this could possibly be more efficient than incremental
> compilation, but I've never worked on a project large enough for compile times to
> be a major issue, so I've never really looked into this.

Maybe incremental compilation could be faster, but dmd has a bug that 
forces tools like dsss/rebuild to use a slower method. Instead of 
invoking the compiler once to recompile all modules that depend from 
changed files, it has to start a new compiler process for each file.

> If incremental compilation were removed from the spec, meaning the compiler would
> always know about the whole program when compiling, I assume (correct me if I'm
> wrong) that would mean the following restrictions could be removed:
> 
> 1.  std.traits could offer a way to get a tuple of all derived classes,
> essentially the opposite of BaseTypeType.
> 2.  Since DMD would know about all derived classes when compiling the base class,
> it would be feasible to allow templates to add virtual functions to classes.
> IMHO, this would be an absolute godsend, as it is currently a _huge_ limitation of
> templates.
> 3.  For the same reason, methods calls to classes with no derived classes could be
> made directly instead of through the vtable.

And you could do all kinds of interprocedural optimizations.

> Of course, these restrictions would still apply to libraries that use .di files.
> If incremental compilation is actually causing more problems than it solves
> anyhow, it would be great to get rid of it along with the annoying restrictions it
> creates.

It seems Microsoft thought the same. C# goes without incremental 
compilation. But for now, D's build model is too similar to C/C++ as 
that you'd completely remove that ability.