[MacPorts] #59108: mercurial 5.1: fails to build with "ld: library not found for -lSystem"

[MacPorts]

#59108: mercurial 5.1: fails to build with "ld: library not found for -lSystem"
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  Reporter:  ylluminarious  |      Owner:  (none)
      Type:  defect         |     Status:  new
  Priority:  Normal         |  Milestone:
 Component:  ports          |    Version:  2.6.0
Resolution:                 |   Keywords:
      Port:  mercurial      |
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Comment (by ylluminarious):

 Replying to [comment:2 ryandesign]:
 > Well, the log shows you're using Xcode 11, yet the build is using flags
 like
 `-Wl,-syslibroot,/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.14.sdk`.
 Xcode 11 does not contain the 10.14 SDK; it only contains the 10.15 SDK.
 There are many other tickets for this issue already.

 Are there any known solutions or workarounds to this problem? Could you
 point me to one of these tickets?

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Ticket URL: <https://trac.macports.org/ticket/59108#comment:3>
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