Jeffrey Walton <noloa...@gmail.com> writes: > This is related to Nick and Mathieu's comments about per-object flags > and use of CXXFLAGS. > > When I change the pattern to: > > CPU_FLAG = -msse2 > libcpu_a_SOURCES = cpu.cpp > libcpu_a_CXXFLAGS += $(CPU_FLAG) > > I encounter: > > Makefile.am:64: error: libcpu_a_CXXFLAGS must be set with '=' before > using '+=' > > I think there are two or three issues with what I am trying to do, and > the issue with "+=" is only the most prominent symptom. > > I think this document may be controlling: > https://www.gnu.org/software/automake/manual/html_node/Flag-Variables-Ordering.html#Flag-Variables-Ordering. > The paragraph that starts with "What we recommend is that you define > extra flags in separate variables...." is especially interesting to > me. It is interesting because `CPU_FLAG` will eventually need to be > computed based on the platform. (Eventually we need: i386 gets -msse2; > x86_64 gets nothing; ARMv7 gets NEON; and PowerPC gets Power4 and > Altivec; others get nothing). > > Please forgive my ignorance, but how do I fix this issue such that it > won't break when I start computing the value of CPU_FLAG in Autoconf?
Maybe I am overlooking something but using '=' shouldn't cause any issue event if CPU_FLAG is computed from Autoconf. -- Mathieu Lirzin GPG: F2A3 8D7E EB2B 6640 5761 070D 0ADE E100 9460 4D37
