Bug#950008: gfan: assertion fails on riscv64

[Torrance, Douglas]

On Tue, 28 Jan 2020 10:29:07 +0100 Tobias Hansen <thansen at debian.org> wrote:
> many of sagemath's doctests in the interface to gfan fail on riscv64 with the following error:
> 
> gfan_*: src/application.cpp:42: char* tail(char*): Assertion `*p==*m' failed.
> 
> It looks like the pointer arithmetic in the function tail() in application.cpp does not work like this on riscv64. Unfortunately there are no porterboxes for riscv64 yet, so I can't come up with a minimal example triggering the bug.

This is also causing macaulay2 to FTBFS in riscv64 [1]:

    checking whether the package gfan is installed... gfan: src/application.cpp:42: char* tail(char*): Assertion `*p==*m' failed.
    yes, but < 0.6, will build
    
    ...
    
    make -C gfan fetch
    make[3]: Entering directory '/<<PKGBUILDDIR>>/M2/libraries/gfan'
    error: for the third-party library or program source "gfan"
           the source code is not present in the file "/<<PKGBUILDDIR>>/M2/BUILD/tarfiles/gfan0.6.2.tar.gz"
           so either download a "fat" tar file of the Macaulay2 source code
           or rerun the Macaulay2 "configure" command with the added option "--enable-download"
           to enable automatic downloading of the source code over the internet
    make[3]: *** [../Makefile.library:235: /<<PKGBUILDDIR>>/M2/BUILD/tarfiles/gfan0.6.2.tar.gz] Error 1

[1] https://buildd.debian.org/status/fetch.php?pkg=macaulay2&arch=riscv64&ver=1.18%2Bds-1%7Eexp1&stamp=1625665959&raw=0