[tor-bugs] #23602 [Core Tor/Tor]: Fix compilation on macOS

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#23602: Fix compilation on macOS
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 Reporter:  hellais       |          Owner:  (none)
     Type:  defect        |         Status:  needs_revision
 Priority:  Medium        |      Milestone:  Tor: 0.3.3.x-final
Component:  Core Tor/Tor  |        Version:
 Severity:  Normal        |     Resolution:
 Keywords:                |  Actual Points:
Parent ID:                |         Points:
 Reviewer:                |        Sponsor:
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Comment (by hellais):

 > The first problem is that we are detecting OpenSSL by looking for
 RAND_add(). That was once okay, but now that we require OpenSSL 1.0.1, we
 should look for a function that was introduced in OpenSSL 1.0.1. We should
 probably make sure that it's something that libressl also has, if
 possible.

 Correct me if I am wrong, but isn't this a separate issue unrelated to
 making the build system work on macOS with homebrew?

 Even if it were to pass in this case, users will in almost every case want
 to use the homebrew version of libraries if they have it installed.

 > The second problem is that our search path doesn't include
 /usr/local/opt/ and /usr/local/opt/openssl/. But we could fix that just by
 adding them.

 That is actually how I originally implemented the fix for this, but that
 will actually not work since the order in which libraries are searched for
 needs to change in macOS. The lookup order there is made to first look for
 system libraries (in this case the crummy macOS default ones) and only
 after the ones in the special prefixes. On macOS the order should be
 inverted.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/23602#comment:6>
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