G++ tbb dependency for c++-17 parallel algorithms

["Phil Endecott" <spam_from_debian_gcc@chezphil.org>]

Dear experts,

I've been trying to get C++-17 parallel algorithms working
with g++ 10 on bullseye, on arm64.

In the end, all that I needed to do was "apt-get install libtbb-dev"
and add -ltbb to my link flags.

It took me a while to discover that. It doesn't help that the
upstream gcc docs say next-to-nothing about the subject.

I am wondering if the Debian packages should at least suggest
or recommend the required tbb packages. (I don't think they do
currently, but I guess I may have missed a suggestion in a
another dependency.)

But... I think it still would have taken me a while to discover
what I needed. For one thing, I was surprised that TBB is not
Intel-only.

Would it do mucg harm for a default g++ installation to include
libtbb-dev by default?

While trying to understand this, I looked in
/usr/share/doc/g++/README.Debian to see if it mentioned parallel
algorithm support. It says "FIXME: Needs update for stretch".
Please consider removing it!


Thanks, Phil.


(Please consider Cc:ing me, I am not subscribed but will check
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