...configuration (for better error messages):

```
configuration "unittest" {
  dflags "-checkaction=context"
}
```

Error:

```
▶ dub test
             Generating...

...1" ENABLE_UNITTEST="" ENABLE_PROFILE="" ENABLE_COVERAGE="" DFLAGS="" dmd-pgo || exit 1

cp generated/linux...

...run` almost twice faster for me.

```
[Environment32]
DFLAGS=-I%@P%/../../src/phobos -I%@P%/../../src...

...lpthread -lm".

My build options are currently:

```
    "dflags-dmd": [ "-v"],
    "lflags": ["-ld_classic"]
```

I tried...

...can e.g. run *optimized* unittests via `DFLAGS=-O dub run -c unittest -b unittest...

...usr/include, just 'dmd'.

....................cut here....................
[Environment32]
DFLAGS=-I/usr/include/dmd/phobos -I/usr...

...with the path to this file
;

[Environment32]
DFLAGS=-I/usr/include/dlang/dmd -L-L...

...config    ./generated/linux/release/64/dmd.conf
DFLAGS    -I./generated/linux/release/64/../../../../druntime/import...

...DIR/builds/library.di"
	dflags "-Hf=$PACKAGE_DIR/builds/library.di"
	dflags "-o-"
	sourceFiles "library...

...DIR/builds/library.di"
	dflags "-Hf=$PACKAGE_DIR/builds/library.di"
	dflags "-o-"
	SourceFile "library...