itpp @4.3.1: version:1:1: error: expected unqualified-id

[tkeep (Tim Keep)]

Fail to install itpp on Big Sur. I've tried a clean install, and even starting again with MacPorts from scratch, installing itpp before anything else.

This is an exert from the main.log file. Any help would be most appreciated.

:info:build [ 13%] Built target itpp_doc
:info:build make[1]: Leaving directory `/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_math_itpp/itpp/work/build'
:info:build make: *** [all] Error 2
:info:build make: Leaving directory `/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_math_itpp/itpp/work/build'
:info:build Command failed:  cd "/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_math_itpp/itpp/work/build" && /usr/bin/make -j16 -w all VERBOSE=ON 
:info:build Exit code: 2
:error:build Failed to build itpp: command execution failed
:debug:build Error code: CHILDSTATUS 14091 2
:debug:build Backtrace: command execution failed
:debug:build     while executing
:debug:build "system {*}$notty {*}$callback {*}$nice $fullcmdstring"
:debug:build     invoked from within
:debug:build "command_exec -callback portprogress::target_progress_callback build"
:debug:build     (procedure "portbuild::build_main" line 8)
:debug:build     invoked from within
:debug:build "$procedure $targetname"

[ryandesign (Ryan Carsten Schmidt)]

The log shows the error is:

version:1:1: error: expected unqualified-id

This is a well-known problem resulting from the collision of the project's VERSION text file with the <version> header in C++20-compatible compilers on case-insensitive filesystems. The solution is for the project not to add a -I flag for the directory that contains the VERSION file or, failing that, renaming the VERSION file to something else, such as VERSION.txt.

This is not a MacPorts- nor macOS-specific problem (though is more prevalent on macOS since Macs usually use a case-insensitive filesystem while other UNIX systems usually do not) and should be ​reported to the developers of itpp. However itpp seems to be rather dormant so we may have to work on a fix for this ourselves.