1612494 - Pass --no-insert-timestamp to lld when building firefox

Status: NEW

(Firefox Build System :: General, defect)

Description

[Tom Ritter [:tjr] (OOTO until 4/30 at least)]

When building (our regular) Windows builds using lld, we should pass --no-insert-timestamp - this will cause lld to omit the timestamp from object files and make the build that much more reproducible.

Comment 1

[Nathan Froyd [:froydnj]]

Is this a subset or a superset of /Brepro? cc-rs apparently already passes /Brepro, and we weirdly have a number of directories that pass /Brepro...maybe we should just start passing /Brepro everywhere instead? Or do we need to pass /Brepro in addition to the lld flag?

Comment 2

[(Away)]

AIUI, --no-insert-timestamp is the mingw-flavored-lld spelling of the flag. COFF-flavored-lld uses -Brepro. So I guess the request here is really to use the latter.

We should double check that Socorro stuff and minidump-debugging still work as expected with this change. (I'm not expecting any problems, since MS's own binaries went to deterministic timestamps some time ago, but just in case...)

Comment 3

[(Away)]

Also, http://blog.llvm.org/2019/11/deterministic-builds-with-clang-and-lld.html suggests setting an explicit -timestamp rather than a bare -Brepro.

Comment 4

[Tom Ritter [:tjr] (OOTO until 4/30 at least)]

Yes, the conclusion here is we should pass --timestamp with an explicit timestamp.

Comment 5

[(Away)]

glandium, fyi: this might make -Brepro unnecessary in cross builds.