--disable-tls does not limit functionality, it only determines how std::call_once works

[Jeffrey Walton]

Hi Everyone/Ken,

I was looking through
https://github.com/kencu/LeopardPorts/blob/master/lang/gcc7/Portfile,
and noticed this comment:

# see https://lists.macports.org/pipermail/macports-dev/2017-August/036209.html
# --disable-tls does not limit functionality
# it only determines how std::call_once works

Based on my testing of i686, x86_64, ARM-32, Aarch64 and PowerPC,
std::call_once is completely broken everywhere except x86_64. When I
tired to use std::call_once in my programs I had truckloads of
unexplained crashes everywhere except x86_64. There's GCC bug report
that details the same.

If possible, GCC should be built without std::call_once. Or
std::call_once should throw std::runtime_error("Not implemented!"). I
don't know if GCC ever fixed std::call_once on non-Intel platforms,
but you should avoid std::call_once. Treat it like the coronavirus.

Off topic, here's some interesting reading on coronavirus and its
origins in horseshoe bats in southern asia:
https://www.scientificamerican.com/article/how-chinas-bat-woman-hunted-down-viruses-from-sars-to-the-new-coronavirus1/

Jeff