Speeding up importing Phobos files

[Nick Sabalausky (Abscissa)]

On 6/7/19 5:47 AM, Mike Franklin wrote:
> 
> Why not remove the arbitrary limitation that a module or package must be 
> tied to a file or directory respectively?

We don't really have that limitation. The compiler gets the 
package/module name from the `module ...;` statement (if any) at the 
beginning of a *.d file. It's only when the `module` statement is absent 
that the package/module name is inferred from the filepath. (There 
*might* also be such a requirement when importing *but not compiling* a 
given module, but I'm not sure on that.)

Beyond that, any other requirement for packages/modules to match the 
filesystem is purely a convention relied upon by certain buildsystems, 
like rdmd (and now, `dmd -i`), and otherwise has nothing to do with the 
compiler.

TBH, I've always kinda wanted to just do away with the ability to have 
modules/packages that DON'T match the filesystem. I never saw any 
sensible use-cases for supporting such weird mismatches that couldn't 
already be accomplished via -I (not to be confused with the new -i) or 
version/static if.

HOWEVER, that said, you do bring up an interesting point I'd never 
thought of: If concating a bunch of modules/packages into one file would 
improve compile time, than that would certainly be a feature worth 
considering.