make: Fix makefile depend generation
The main goal of this is to fix "make --question -C cryptoc" behavior
for projects that depend on this library (Chromium EC, Cr50).
Without this fix, when invoking make with the --question flag,
a full build of all *.o was triggered, minus libcryptoc.a.
This was because the "-include $(DEPS)" make step depended on *.d
files. That would then trigger the primary "$(obj)/%.d $(obj)/%.o"
rule, which [yes generated .d files, but] generated the objects.
The following article explains the art of makefile depends quite well:
http://make.mad-scientist.net/papers/advanced-auto-dependency-generation
BUG=none
TEST=make clean; make -q && echo Fail
# No CC builds should occur and no Fail was emitted
# Before this change, the make -q would trigger a build
TEST=make clean; make || echo Fail; make -q || echo Fail
# No Fail should be emitted
TEST=make
touch include/cryptoc/sha.h
make
# See sha.o, hmac.o, and libcryptoc.a being remade
TEST=make
touch include/cryptoc/util.h
make
# See hmac.o, util.o, and libcryptoc.a being remade
TEST=make
mv include/cryptoc/util.h include/cryptoc/utill.h
# Change header reference in util.c and hmac.c
make
# See hmac.o, util.o, and libcryptoc.a being remade
TEST=# Run the following for a few minutes
while true; do \
make clean &>/dev/null; \
make -q && echo Fail; \
make -j &>/dev/null; \
make -q || echo Fail; \
make clean &>/dev/null; \
make -q && echo Fail; \
make &>/dev/null; \
make -q || echo Fail; \
echo -n .; \
done
Change-Id: I1ec8a9acca06d8475011563365b57a16f65b2e84
1 file changed
