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Sources from subdirectories in Makefile

Asked 2010-10-27T17:58:45.420
88

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?

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2 Answers

109

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.)

answered 2010-10-27T23:08:50.987
35

Recursive wildcards can be done purely in Make, without calling the shell or the find command. Doing the search using only Make means that this solution works on Windows as well, not just *nix.

# Make does not offer a recursive wildcard function, so here's one:
rwildcard=$(wildcard $1$2) $(foreach d,$(wildcard $1*),$(call rwildcard,$d/,$2))

# How to recursively find all files with the same name in a given folder
ALL_INDEX_HTMLS := $(call rwildcard,foo/,index.html)

# How to recursively find all files that match a pattern
ALL_HTMLS := $(call rwildcard,foo/,*.html)

The trailing slash in the folder name is required. This rwildcard function does not support multiple wildcards the way that Make's built-in wildcard function does, but adding that support would be straightforward with a couple more uses of foreach.

answered 2012-10-18T16:52:00.917

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