cmake: Sort source files for reproducible builds #5523
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We currently use `FILE(GLOB ...)` in most places to find source and header files. This is problematic in that the order of files returned depends on the operating system's directory iteration order and may thus not be deterministic. As a result, we link object files in unspecified order, which may cause the linker to emit different code across runs. Fix this issue by sorting all code used as input to the libgit2 library to improve the reliability of reproducible builds.
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utkarsh2102
reviewed
May 15, 2020
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Hi Patrick,
With this patch applied, the CI still fails :/
cf: https://salsa.debian.org/debian/libgit2/pipelines/136877
Reprotest is still failing :/
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Additionally, I also wanted you to know that in Debian, we remove the embedded |
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Huh, that's unfortunate, especially so as I can't reproduce locally
anymore: each run produces the exact same binary on my machine. I
wouldn't think that removing "deps/" should break reproducibility, but
they're kind of fragile, so don't take my word for it.
You probably have some custom patches, right? My recommendation would be
to go from the most vanilla configuration of libgit2, check
reproducability, and then iteratively apply the next batch of
modifcications. Rinse and repeat, until you find the culprit. Likely,
it's already happening in the vanilla configuration.
Maybe hard to do, but if you have a minimal script that shows the
un-reproducible build then that might be very helpful to us to reproduce
the issue.
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By the way, this PR should still be merged regardless of whether it
fixes the original issue, as it definitely fixes _some_ unreproducible
builds already. I'll create a separate PR as soon as we find out what
the issue is that Debian is running into.
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ethomson
approved these changes
May 23, 2020
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We currently use
FILE(GLOB ...)in most places to find source andheader files. This is problematic in that the order of files returned
depends on the operating system's directory iteration order and may thus
not be deterministic. As a result, we link object files in unspecified
order, which may cause the linker to emit different code across runs.
Fix this issue by sorting all code used as input to the libgit2 library
to improve the reliability of reproducible builds.
Fixes #5521