[tor-bugs] #31552 [Core Tor]: --disable-module-dirauth broken (missing symbols)

Tor Bug Tracker & Wiki blackhole at torproject.org
Thu Aug 29 13:54:49 UTC 2019


#31552: --disable-module-dirauth broken (missing symbols)
-------------------------------------------------+-------------------------
 Reporter:  LarryBitcoin                         |          Owner:  nickm
     Type:  defect                               |         Status:
                                                 |  accepted
 Priority:  Medium                               |      Milestone:  Tor:
                                                 |  0.4.1.x-final
Component:  Core Tor                             |        Version:  Tor:
                                                 |  0.4.1.5
 Severity:  Normal                               |     Resolution:
 Keywords:  build, configure, features,          |  Actual Points:
  modules, regression                            |
Parent ID:                                       |         Points:
 Reviewer:                                       |        Sponsor:
-------------------------------------------------+-------------------------

Comment (by nickm):

 Bug confirmed.

 What does the compiler do when it sees:
 {{{
    void function();
    // ...
    if (0) {
      function();
    }
 }}}
 but function() is never actually defined?

 Usually, the compiler will remove the code in the if (0) block, so that by
 the time the linker sees it, the call to function() is no longer there.

 But there are at least two circumstances in which the call to function()
 might last long enough for the linker to see that function() doesn't
 exist.

 1. When building with LTO, the call to function() might not get removed
 until later on.
 2. When building with -O0, the call won't get removed at all.

 I've reproduced these warnings by building Tor with -O0.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/31552#comment:7>
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