Sources from subdirectories in Makefile

Question

I have a C++ library built using a Makefile. Until recently, all the sources were in a single directory, and the Makefile did something like this

SOURCES = $(wildcard *.cpp)

which worked fine.

Now I've added some sources that are in a subdirectory, say subdir. I know I can do this

SOURCES = $(wildcard *.cpp) $(wildcard subdir/*.cpp)

but I'm looking for a way to avoid specifying subdir manually, that is, make wildcard look into subdirectories, or generating a list of subdirectories somehow and expanding it with several wildcard functions. At this point, having a non-recursive solution (that is, expanding only the first level) would be fine.

I haven't found anything - my best guess is using find -type d to list the subdirectories, but it feels like a hack. Is there any built-in way to do this?

Answer 1

This should do it:

SOURCES = $(wildcard *.cpp) $(wildcard */*.cpp) 

If you change you mind and want a recursive solution (i.e. to any depth), it can be done but it involves some of the more powerful Make functions. You know, the ones that allow you to do things you really shouldn't.

EDIT:
Jack Kelly points out that $(wildcard **/*.cpp) works to any depth, at least on some platforms, using GNUMake 3.81. (How he figured that out, I have no idea.)