What to pass to --with-custom-make-dir?

[Christian Thalinger]

At Twitter we are using the custom extension mechanism to separate our additional code from upstream in order to minimize conflicts.  Yesterday I wanted to add a custom extension for:

jdk/make/lib/ServiceabilityLibraries.gmk

which has this include directive:

# Include custom extensions if available.
-include $(CUSTOM_MAKE_DIR)/lib/ServiceabilityLibraries.gmk

We are already using the mechanism for top-level make files, e.g. make/Main.gmk:

# Include the corresponding custom file, if present.
-include $(CUSTOM_MAKE_DIR)/Main.gmk

and we a configuring with:

--with-custom-make-dir=make/closed

This works fine for make/ but not for jdk/make/:

$ make jdk CUSTOM_MAKE_DIR=make/closed
…

## Starting jdk
lib/ServiceabilityLibraries.gmk:27: make/closed/lib/ServiceabilityLibraries.gmk: No such file or directory
make[2]: *** No rule to make target `make/closed/lib/ServiceabilityLibraries.gmk'.  Stop.
make[1]: *** [libs-only] Error 2
make: *** [jdk-only] Error 2

(I changed "-include" to “include” to provoke the error.)

jdk/make/ files expect CUSTOM_MAKE_DIR to be just “closed” but that doesn’t work for top-level:

$ make jdk CUSTOM_MAKE_DIR=closed
/Users/cthalinger/twitter8//make/Main.gmk:35: closed/Main.gmk: No such file or directory
make: *** No rule to make target `closed/Main.gmk'.  Stop.

How is this supposed to work?