On 06/30/2015 06:23 PM, Manuel López-Ibáñez wrote: > On 30 June 2015 at 17:18, Dhole <dh...@openmailbox.org> wrote: >> In the debian reproducible builds project we have considered several >> options to address this issue. We considered redefining the __DATE__ and >> __TIME__ defines by command line flags passed to gcc, but as you say, >> that triggers warnings, which could become errors when building with >> -Werror and thus may require manual intervention on many packages. > > Well, it would require adding -Wno-something (-Wno-reproducible? > -Wno-unreproducible? or perhaps simply -freproducible? ) to some > CFLAGS/CXXFLAGS. Is that too much manual intervention? (I'm asking > sincerely, perhaps indeed it is).
Our idea with the SOURCE_DATE_EPOCH env var was to find a general solution for all toolchain packages involved in the build process that embed timestamps. We already have a patched version of a package used during Debian builds (debhelper) which sets the SOURCE_DATE_EPOCH in the build environment. With the submitted patch to GCC nothing else would be needed, and we believe it would be useful to other projects working on reproducible builds, as they would only need to set the SOURCE_DATE_EPOCH env var during their build process. Modifying the CFLAGS/CXXFLAGS would need more intervention during the build process, and this would be a solution only useful for GCC and not other toolchain packages. It could be done, but we'd prefer the general approach. As mentioned before, we are trying to create a standard way of modifying timestamp embedding behavior for any package with the SOURCE_DATE_EPOCH. > This could be a big hammer option that simply disables any warning > that is not relevant for reproducible builds (the default being > -Wsomething), for example avoid emitting --Wbuiltin-macro-redefined > warnings in the specific cases of __TIME__ and __DATE. Just an idea, > the maintainers would need to say if they would accept such an option. > > Cheers, > > Manuel. > I'm looking forward to hear opinions from the maintainers :) Regards, -- Dhole
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