esmf @7_1_0r +gcc8: build error: 'size_t' does not name a type

[Dave-Allured (Dave Allured)]

port -v install esmf +gcc8 fails with multiple C++ errors like this. I shortened several long sequences for readability. See main.log for the full details:

:info:build /Users/dallured/macports/254/bin/g++-mp-8 -c [OPTIONS] [INCLUDES] [LONG_PATH]/ESMCI_CoordSys.C
:info:build In file included from [LONG_PATH]/ESMC_Util.h:23,
:info:build                  from [LONG_PATH]/ESMCI_Fraction.h:52,
:info:build                  from [LONG_PATH]/ESMCI_Fraction.C:25:
:info:build [LONG_PATH]/ESMC_Conf.h:34:9: error: 'size_t' does not name a type
:info:build  typedef size_t ESMCI_FortranStrLenArg;
:info:build          ^~~~~~
:info:build [LONG_PATH]/ESMC_Conf.h:34:9:
        note: 'size_t' is defined in header '<cstddef>'; did you forget to '#include <cstddef>'?
:info:build [LONG_PATH]/ESMC_Conf.h:1:1:
:info:build +#include <cstddef>
:info:build  #ifdef ESMC_RCS_HEADER

Starting from an empty Macports directory, port -v install esmf installs 58 ports successfully, then ESMF fails as above. The default ESMF variant seems to install fine for me, and does not get these errors. Here is my configuration:

sw_vers:
ProductName:	Mac OS X
ProductVersion:	10.13.6
BuildVersion:	17G65

Xcode 10.0
Build version 10A255

I am installing to a private user directory, not /opt/local. Root privileges are disabled. I ran port selfupdate in advance, of course.

[Dave-Allured (Dave Allured)]

main.log from ESMF build failure