[tor-bugs] #26475 [Applications/Tor Browser]: ESR60-based .dmg images are not built reproducibly with Stylo enabled using rustc > 1.25.0

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#26475: ESR60-based .dmg images are not built reproducibly with Stylo enabled using
rustc > 1.25.0
-------------------------------------------------+-------------------------
 Reporter:  gk                                   |          Owner:  tbb-
                                                 |  team
     Type:  defect                               |         Status:
                                                 |  needs_information
 Priority:  Very High                            |      Milestone:
Component:  Applications/Tor Browser             |        Version:
 Severity:  Normal                               |     Resolution:
 Keywords:  tbb-rbm, GeorgKoppen201808,          |  Actual Points:
  TorBrowserTeam201808                           |
Parent ID:                                       |         Points:
 Reviewer:                                       |        Sponsor:
-------------------------------------------------+-------------------------

Comment (by alexcrichton):

 Nice! Bisecting to the LLVM upgrade definitely makes sense to me. That was
 a massive LLVM upgrade though (from LLVM 4.0 to LLVM 6.0), so that would
 be quite the bisection range for a regression to be introduced in :(

 If it works, though, when you build LLVM yourself that's quite curious.
 The command we use to build LLVM though is pretty huge. Looking at one of
 our  recent builds (https://travis-ci.org/rust-lang/rust/builds/411219658)
 the command we use on OSX is:

 {{{
 "cmake" "/Users/travis/build/rust-lang/rust/src/llvm"
 "-DLLVM_ENABLE_ASSERTIONS=OFF"
 "-DLLVM_TARGETS_TO_BUILD=X86;ARM;AArch64;Mips;PowerPC;SystemZ;MSP430;Sparc;NVPTX;Hexagon"
 "-DLLVM_EXPERIMENTAL_TARGETS_TO_BUILD=WebAssembly;RISCV"
 "-DLLVM_INCLUDE_EXAMPLES=OFF" "-DLLVM_INCLUDE_TESTS=OFF"
 "-DLLVM_INCLUDE_DOCS=OFF" "-DLLVM_ENABLE_ZLIB=OFF" "-DWITH_POLLY=OFF"
 "-DLLVM_ENABLE_TERMINFO=OFF" "-DLLVM_ENABLE_LIBEDIT=OFF"
 "-DLLVM_ENABLE_LIBXML2=OFF" "-DLLVM_PARALLEL_COMPILE_JOBS=4"
 "-DLLVM_TARGET_ARCH=x86_64" "-DLLVM_DEFAULT_TARGET_TRIPLE=x86_64-apple-
 darwin" "-DLLVM_OCAML_INSTALL_PATH=usr/lib/ocaml"
 "-DCMAKE_EXE_LINKER_FLAGS=-static-libstdc++" "-DCMAKE_C_COMPILER=sccache"
 "-DCMAKE_C_COMPILER_ARG1=/Users/travis/build/rust-
 lang/rust/clang+llvm-6.0.0-x86_64-apple-darwin/bin/clang"
 "-DCMAKE_CXX_COMPILER=sccache"
 "-DCMAKE_CXX_COMPILER_ARG1=/Users/travis/build/rust-
 lang/rust/clang+llvm-6.0.0-x86_64-apple-darwin/bin/clang++"
 "-DCMAKE_C_FLAGS=-ffunction-sections -fdata-sections -fPIC --target=x86_64
 -apple-darwin -stdlib=libc++" "-DCMAKE_CXX_FLAGS=-ffunction-sections
 -fdata-sections -fPIC --target=x86_64-apple-darwin -stdlib=libc++"
 "-DCMAKE_INSTALL_PREFIX=/Users/travis/build/rust-lang/rust/build/x86_64
 -apple-darwin/llvm" "-DCMAKE_BUILD_TYPE=Release"
 }}}

 I wonder if perhaps the way we compile LLVM is affecting this? Maybe some
 flag or maybe our own compiler we use on automation is introducing bugs?
 Or maybe it has to do with the C++ standard library and which is used?

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/26475#comment:34>
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