[MacPorts] #62440: perl5: invalid SDK path hardcoded on macOS 11

[MacPorts]

#62440: perl5: invalid SDK path hardcoded on macOS 11
--------------------------+----------------------
 Reporter:  chrstphrchvz  |      Owner:  mojca
     Type:  defect        |     Status:  assigned
 Priority:  Normal        |  Milestone:
Component:  ports         |    Version:
 Keywords:                |       Port:  perl5
--------------------------+----------------------
 While [https://github.com/macports/macports-ports/pull/10181 trying to
 update] `p5-tk` I observed CI builds fail on macOS 11 Big Sur.

 {{{
 /usr/bin/clang -o perlrx -fno-common -DPERL_DARWIN -mmacosx-version-
 min=10.16 -pipe -Os
 -isysroot/Library/Developer/CommandLineTools/SDKs/MacOSX11.0.sdk  -fno-
 strict-aliasing -fstack-protector-strong -I/opt/local/include
 -DPERL_USE_SAFE_PUTENV -I/opt/local/lib/perl5/5.26/darwin-thread-multi-
 2level/CORE config/perlrx.c  -mmacosx-version-min=10.16 -L/opt/local/lib
 -Wl,-headerpad_max_install_names
 -Wl,-syslibroot,/Library/Developer/CommandLineTools/SDKs/MacOSX11.0.sdk
 -fstack-protector-strong  -c
 clang: warning: -Wl,-headerpad_max_install_names: 'linker' input unused
 [-Wunused-command-line-argument]
 clang: warning:
 -Wl,-syslibroot,/Library/Developer/CommandLineTools/SDKs/MacOSX11.0.sdk:
 'linker' input unused [-Wunused-command-line-argument]
 clang: warning: no such sysroot directory:
 '/Library/Developer/CommandLineTools/SDKs/MacOSX11.0.sdk' [-Wmissing-
 sysroot]
 clang: warning: argument unused during compilation: '-L/opt/local/lib'
 [-Wunused-command-line-argument]
 In file included from config/perlrx.c:2:
 /opt/local/lib/perl5/5.26/darwin-thread-multi-2level/CORE/perl.h:694:10:
 fatal error: 'sys/types.h' file not found
 #include <sys/types.h>
          ^~~~~~~~~~~~~
 1 error generated.
 }}}

 The `p5-tk` port (and likely others) currently relies on the compiler and
 flags hardcoded in Perl itself (I am struggling to get `p5-tk` to
 completely respect custom compiler/flags settings). The MacOSX11.0.sdk
 directory is reportedly no longer present on an up-to-date macOS 11
 system, but it is hardcoded in the already-built packages of `perl5.xx`
 ports e.g. in Config_heavy.pl. Ideally an unversioned SDK path can get
 hardcoded instead.

 I'm not sure exactly which version of MacPorts base the packages were
 built with (either 2.6.3 or 2.6.4), and whether that has an effect here. I
 personally do not use macOS 11.

-- 
Ticket URL: <https://trac.macports.org/ticket/62440>
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