On Tue, Jun 28, 2016 at 19:21:45 +0200, Grégory Pakosz wrote: > Hello, > > What's the rationale behind Automake passing CFLAGS or CXXFLAGS when linking? > > LINK = $(LIBTOOL) $(AM_V_lt) --tag=CC $(AM_LIBTOOLFLAGS) \ > $(LIBTOOLFLAGS) --mode=link $(CCLD) $(AM_CFLAGS) $(CFLAGS) \ > $(AM_LDFLAGS) $(LDFLAGS) -o $@ > > CXXLINK = $(LIBTOOL) $(AM_V_lt) --tag=CXX $(AM_LIBTOOLFLAGS) \ > $(LIBTOOLFLAGS) --mode=link $(CXXLD) $(AM_CXXFLAGS) \ > $(CXXFLAGS) $(AM_LDFLAGS) $(LDFLAGS) -o $@ > > In comparison, GNU Make's default linking rule is > > .o: > $(LINK.o) $^ $(LOADLIBES) $(LDLIBS) -o $@ > > where LINK.o = $(CC) $(LDFLAGS) $(TARGET_ARCH)
I don't know if I can tell you an offical project rationale, but I can give a couple examples of options that you really do want to appear in both places, -pthread and -fopenmp. If automake did not invoke the link stage this way, building with CFLAGS=-fopenmp but forgetting to include it in LDFLAGS might cause serious problems. OTOH asking the compiler to link some object code and including a few options that have nothing to do with linking should be harmless. -- mike
