[MacPorts] #58998: port @2.5.99 fails to build a port - in this case ldns.

[MacPorts]

#58998: port @2.5.99 fails to build a port - in this case ldns.
-----------------------+--------------------
 Reporter:  snowflake  |      Owner:  (none)
     Type:  defect     |     Status:  new
 Priority:  Normal     |  Milestone:
Component:  base       |    Version:  2.5.99
 Keywords:             |       Port:
-----------------------+--------------------
 port @2.5.99 does not build some ports, while port @2.5.4 does build them.

 Environment: macOS 10.11.6, Xcode 8.2.1

 Related tickets #58909 for clang-8.0 and #58907 for clang-3.9.

 I have bisected the port command and the failing commit in macports-base
 is:

 {{{
 commit 057ce2b2bfe8d08cafe3f98296546f6a060790ab (refs/bisect/bad)
 Author: Satryaji Aulia <satraul at macports.org>
 Date:   2019-06-13 16:24:38 +0100

     port1.0: Implement use_xcode option

     * implement new option use_xcode to indicate Xcode dependency
     * default DEVELOPER_DIR to Command Line Tools unless port needs Xcode
     * hide Xcode files on trace mode unless port needs Xcode
     * fail fetch phase of Xcode-dependent port if Xcode is not installed

     References https://trac.macports.org/ticket/35045
     References https://trac.macports.org/ticket/58016
 }}}

 In all 3 cases of build failure  -isysroot for clang does not receive an
 argument.

 It seems to be caused by port using commands in /Library/Developer instead
 of Applications/Xcode.app.
 Diff'ing the good and bad logs for the ldns build shows this (logs are
 attached).

 It is entirely possible that my command line tools are out of date or
 something else equally silly.
 I have built many ports in the last two weeks and only three of them have
 failed in this manner.

-- 
Ticket URL: <https://trac.macports.org/ticket/58998>
MacPorts <https://www.macports.org/>
Ports system for macOS