How to get a Makefile’s directory for including other Makefiles

I experience this problem:

I have a file common.mk that includes release.mk which in the same directory. common.mk is included by the top-level Makefile. common.mk and release.mk are shared by multiple projects and the top-level Makefile may stay in different directories with {common,release}.mk.

Now, include in make use the pwd as base directory. So, simply include release.mk does not work if the top-level Makefile is not in the same directory as releas.mk.

For example, in a directory structure like

Makefile
common.mk
release.mk

it is find. But for

Makefile
external/common.mk
external/release.mk

The same include release.mk in commin.mk will reports that release.mk does not exists.

In bash, we can use $(dirname $0) to get the current script’s directory. How to achieve the similar thing in Makefile so that I can use include $(self_dir)/release.mk?

The key is to find the “current” makefile’s directory:

SELF_DIR := $(dir $(lastword $(MAKEFILE_LIST)))

SELF_DIR will contain the directory of the makefile which contains this piece of code. So you can include the release.mk by:

include $(SELF_DIR)/release.mk

This will not reply on which directory the top-level Makefile stay in anymore.