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 +gcc8 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