Hi, I want to add "EXTRA_CFLAGS += -Werror=date-time" to the Makefile of my kernel module project (https://github.com/diederikdehaas/rtl8812AU) to support Reproducible Builds. But this makes the build fail when using Jessie (or older) since that flag isn't supported on GCC < 4.9. While gcc-4.9 is the default on Jessie, it looks like gcc-4.8 is used by default, which matches the value from /proc/version. There's a similar mismatch on Sid (and probably Stretch). I thought to be able to handle my situation by doing "$(CC) -dumpversion" and this seems to work when make is invoked like "make CC=/usr/bin/gcc-4.9". But when it's invoked with just "make" then $(CC) is reported back as "cc" and "cc -dumpversion" reports back the version of the _default_ compiler version, but as I described above that's not the same as the one actually used to compile my module. How can I make my Makefile work across different Debian versions and also when make is invoked as just "make" and "make CC=/usr/bin/gcc-<version>" ? (Preferably across distributions, but my main concern is Debian/Raspbian) TIA, Diederik PS: I also want to add other compiler flags conditionally, but I guess the principle would be the same for all.
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