[Octave-bug-tracker] [bug #55363] Global variable in a MEX file

[Guillaume]

Follow-up Comment #9, bug #55363 (project octave):

Adding '-Wl,-Bsymbolic-functions' manually to the Matlab mex compilation
command line does not change the behavior. Matlab seems to use the
'-Wl,--version-script=' flag,  which probably takes precedence.

On Ubuntu, the '-Wl,-Bsymbolic-functions' link option comes from
$OCT_LINK_OPTS. If I redefine it to contain '-Wl,-z,relro' only before calling
mkoctfile, then everything works fine again. $OCT_LINK_OPTS seems to be
populated from $LDFLAGS.

I could find a number of related discussions, where that flag created similar
issues:

https://lists.ubuntu.com/archives/ubuntu-devel/2018-June/040369.html
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=637184
https://bugs.launchpad.net/ubuntu/+source/tango/+bug/1250534
https://github.com/grpc/grpc/issues/11195

Would there be a way to automatically strip '-Wl,-Bsymbolic-functions' from
$LDFLAGS if present? As mentioned in comments #4 and #5, it cannot be assumed
to be able to declare all functions and variables to be static in a MEX file.
For example, I could find this being described here:

http://anadoxin.org/blog/control-over-symbol-exports-in-gcc.html

with the solution to use '-Wl,--version-script='.

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