[TTR fails] to install with gcc trunk which is due to be released as gcc
10.0.x early in 2020. It defaults to -fno-common, which stricter on
some multiply-defined symbols -- see §1.6.4.1 of 'Writing R Extensions'
in current R-devel.
We expect the issues to also be seen when compiling with earlier
versions of gcc using the (non-default) flag -fno-common: this has been
confirmed for gcc 9 on Linux, and also for clang on macOS.
Add -fno-common to PKG_CFLAGS in ~/.R/Makevars to reproduce.
From Prof Ripley:
Add
-fno-common
toPKG_CFLAGS
in~/.R/Makevars
to reproduce.