On Monday, 22 August 2016 at 11:45:37 UTC, Matthias Klumpp wrote:
One important thing about Ninja is that it will perform split-builds by default, so if you change something, only the changed piece needs to be recompiled. I *think* dub can do that too, but for some reason it never does it (even when using --parallel). That behavior drastically reduces compile times when working on a project.
So if I understand correctly, Meson/Ninja compile each module separately, while dub builds them all in a single command line. This makes quite a big difference. Compiling all at once requires a full rebuild every time a single file is modified and implies full single-threadedness. The advantages are that each file is only loaded and parsed once, but much more importantly, everything is emitted into a single object file, allowing for implicit full cross-module inlining (across the compiled modules). So while compiling each file separately in parallel is potentially much much faster, the produced release binary may be slower due to less/no cross-module inlining (e.g., LDC's option is still experimental and known to have issues).