Make make rebuild a target when it depends on a deleted file

Question

Suppose I have a make rule like this:

SOURCES := $(wildcard ./text/*.txt)

$(INDEX) : $(SOURCES)
    $(COMPILER) $(SOURCES)

And then one of the text files, ./text/foo.txt, is deleted. The target $(INDEX) does not seem to be rebuilt. How do I make make rebuild in this case?

Answer 1

If your ./text directory contains only your sources and all of them, you can add it as a pre-requisite of your target:

$(INDEX) : $(SOURCES) ./text

Directories are not like regular files: their last modification date is updated when you add, delete or rename a file (or subdirectory) in them, not when an existing file is modified. Think of it as a file containing the list of contained files.