Try using libtool to enable building dub static library dependencies per package

[atilaneves]

This ninja rule should do it:

libtool --mode=link --tag=CC cc -o $out $in

[kinke]

This is crucial, I've just stumbled upon this as major blocker for effective parallelization. So currently each static lib dub dependency is built via dmd -lib <all src files>, which makes the compiler compile all modules at once to individual object files and then archive them to a static lib. To replicate this with per-D-package building, the compiler would need to be invoked like this:

dmd -c src/a/a1.d src/a/a2.d -od=objs -op
=> builds package a: objs/src/a/a{1,2}.o
dmd -c src/b/b1.d src/b/b2.d -od=objs -op
=> builds package b: objs/src/b/b{1,2}.o
dmd -lib -ofmylib.a objs/src/a/a{1,2}.o objs/src/b/b{1,2}.o
=> using the D compiler for archiving allows LTO libs to be archived with LDC (not supported by ar)