[tbb-bugs] #28238 [Applications/Tor Browser]: Use mingw-w64/clang toolchain to build Firefox

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#28238: Use mingw-w64/clang toolchain to build Firefox
-------------------------------------------------+-------------------------
 Reporter:  gk                                   |          Owner:  tbb-
                                                 |  team
     Type:  defect                               |         Status:  new
 Priority:  High                                 |      Milestone:
Component:  Applications/Tor Browser             |        Version:
 Severity:  Normal                               |     Resolution:
 Keywords:  tbb-rbm, TorBrowserTeam201901,       |  Actual Points:
  GeorgKoppen201902                              |
Parent ID:  #29318                               |         Points:
 Reviewer:                                       |        Sponsor:
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Comment (by gk):

 Replying to [comment:6 gk]:
 > Replying to [comment:4 gk]:
 > > Testing `bug_28238` shows that we have some reproducibility issues
 with mingw-w64/clang. It seems we have to deal at least with timestamp
 issues in the COFF header. Comparing e.g. `firefox.exe` from two different
 runs shows:
 > > {{{
 > > --- /dev/fd/63      2019-01-10 09:38:08.159230047 +0100
 > > +++ /dev/fd/62      2019-01-10 09:38:08.159230047 +0100
 > > @@ -6,7 +6,7 @@
 > >  00000050: 6973 2070 726f 6772 616d 2063 616e 6e6f  is program canno
 > >  00000060: 7420 6265 2072 756e 2069 6e20 444f 5320  t be run in DOS
 > >  00000070: 6d6f 6465 2e24 0000 5045 0000 4c01 0600  mode.$..PE..L...
 > > -00000080: 3b1c 365c 003c 0000 a201 0000 e000 2201  ;.6\.<........".
 > > +00000080: 45ff 365c 003c 0000 a201 0000 e000 2201  E.6\.<........".
 > >  00000090: 0b01 0e00 001e 0000 001a 0000 0000 0000  ................
 > >  000000a0: c013 0000 0010 0000 0000 0000 0000 4000  .............. at .
 > >  000000b0: 0010 0000 0002 0000 0600 0000 0000 0000  ................
 > > }}}
 >
 > FWIW: That's still an unsolved issue after bumping the LLVM revision to
 r348363.

 That is solved and in the process of being upstreamed. I now get identical
 builds on one machine. However, compared to the other one I tested they
 significantly differ. Not all .dlls/.exe files are affected, though, just
 `firefox.exe`, `libGLESv2.dll`, `mozglue.dll`, `pingsender.exe`, `plugin-
 container.exe`, `plugin-hang-ui.exe`, and `xul.dll`.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/28238#comment:20>
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