Question

I know that

Make figures out automatically which files it needs to update, based on which source files have changed. It also automatically determines the proper order for updating files, in case one non-source file depends on another non-source file.

As a result, if you change a few source files and then run Make, it does not need to recompile all of your program. It updates only those non-source files that depend directly or indirectly on the source files that you changed.

Now I want to know whether I can ask Make to list out these modified sources?

Answer 1

You’ll need a dummy file which uses all of your sources as prerequisites:

mod_list: foo.c bar.cc baz.cpp
    @echo modified sources: $?
    @touch $@

You can keep the list of sources as a separate variable:

WATCHED_SOURCES = foo.c bar.cc baz.cpp
mod_list: $(WATCHED_SOURCES)
    @echo modified sources: $?
    @touch $@

Or use a wildcard to look at all sources present:

WATCHED_SOURCES = $(wildcard *.c *.cc *.cpp *.whatever)
mod_list: $(WATCHED_SOURCES)
    @echo modified sources: $?
    @touch $@