qpdf fails to configure on Lion - "A compiler with support for C++14 language features is required"

[RobK88]

qpdf fails the configure stage on Lion (10.7.5)

Macports reports "configure: error: * A compiler with support for C++14 language features is required."

Here is an excerpt of the error:

sudo port -v upgrade qpdf
....
checking whether /usr/bin/clang++ supports C++14 features with ... no
checking whether /usr/bin/clang++ supports C++14 features with -std=c++14... no
checking whether /usr/bin/clang++ supports C++14 features with +std=c++14... no
checking whether /usr/bin/clang++ supports C++14 features with -h std=c++14... no
checking whether /usr/bin/clang++ supports C++14 features with ... (cached) no
checking whether /usr/bin/clang++ supports C++14 features with -std=c++1y... no
checking whether /usr/bin/clang++ supports C++14 features with +std=c++1y... no
checking whether /usr/bin/clang++ supports C++14 features with -h std=c++1y... no
configure: error: *** A compiler with support for C++14 language features is required.
Command failed:  cd "/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_release_tarballs_ports_textproc_qpdf/qpdf/work/qpdf-10.2.0" && ./configure --prefix=/opt/local 
Exit code: 1
Error: Failed to configure qpdf, consult /opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_release_tarballs_ports_textproc_qpdf/qpdf/work/qpdf-10.2.0/config.log
Error: Failed to configure qpdf: configure failure: command execution failed
Error: See /opt/local/var/macports/logs/_opt_local_var_macports_sources_rsync.macports.org_release_tarballs_ports_textproc_qpdf/qpdf/main.log for details.
Error: Follow https://guide.macports.org/#project.tickets to report a bug.

Here is the fix -- I was able to configure and build qpdf on Lion using Clang-9.0. (A version of clang earlier that 9.0 might work but I did not test it).

bash-3.2$ sudo port clean qpdf
Password:
--->  Cleaning qpdf
bash-3.2$ 
bash-3.2$ sudo port -v upgrade qpdf configure.compiler=macports-clang-9.0
bash-3.2$ 
bash-3.2$ qpdf --version
qpdf version 10.2.0
Run qpdf --copyright to see copyright and license information.

[jmroot (Joshua Root)]

"A C++-14 compiler is now required to build qpdf." – ​http://qpdf.sourceforge.net/files/qpdf-manual.html#ref.release-notes

[jmroot (Joshua Root)]

In ec17d5597225806f3e7dd7b190de17d531a7244c/macports-ports (master):

qpdf: needs C++14

Fixes: #62381