Require C++17

[olupton]

Let's see what breaks...

Based on https://en.cppreference.com/w/cpp/compiler_support/17, this will correspond to requiring ~GCC7 or ~Clang5.

TODO:

• Document that flex 2.6+ is required (older versions emit the register keyword)
• Make sure CI plans only use new-enough dependencies.
• Update just before the merge https://hub.docker.com/repository/docker/neuronsimulator/neuron_wheel and https://hub.docker.com/repository/docker/neuronsimulator/neuron_wheel_gpu to include Flex >= 2.6.
• Require C++17 in CoreNEURON too, update submodule after merging Require C++17 BlueBrain/CoreNeuron#834.
• Require C++17 in InterViews too, update submodule. Need to fix Avoid using namespace std in headers. iv#43 first by merging Bump to C++17 iv#44.
• Require C++17 in NMODL too (Require C++17. BlueBrain/nmodl#889)

[alkino]

When you bump version of nrn, you can in the same time bump the one for InterViews. Normally it's already c++17 ready due to: neuronsimulator/iv#39

[pramodk]

Document that flex 2.6+ is required (older versions emit the register keyword)

@olupton: Does any of our CI (images) from nrn-build-ci include flex < 2.6?

Edit: Hmm..Ok, I see the failing CIs.

[olupton]

Document that flex 2.6+ is required (older versions emit the register keyword)

@olupton: Does any of our CI (images) from nrn-build-ci include flex < 2.6?

macOS-10.15 (regular CI + nrn-build-ci) does: https://github.com/neuronsimulator/nrn/runs/7128845752#step:14:216
So does centos:7 in nrn-build-ci: https://github.com/neuronsimulator/nrn-build-ci/runs/7143554190#step:7:184

[codecov-commenter]

Codecov Report

Merging #1893 (12530f3) into master (20c3abe) will decrease coverage by 0.03%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##           master    #1893      +/-   ##
==========================================
- Coverage   47.17%   47.13%   -0.04%     
==========================================
  Files         543      543              
  Lines      112912   112912              
==========================================
- Hits        53264    53219      -45     
- Misses      59648    59693      +45     

Impacted Files	Coverage Δ
src/ivoc/apwindow.cpp	4.46% <0.00%> (ø)
src/ivoc/axis.cpp	0.32% <0.00%> (ø)
src/ivoc/epsprint.cpp	7.14% <0.00%> (ø)
src/ivoc/graph.cpp	10.38% <0.00%> (ø)
src/ivoc/idraw.cpp	0.31% <0.00%> (ø)
src/ivoc/ivoc.h	0.00% <ø> (ø)
src/ivoc/ivocmain.cpp	74.28% <ø> (ø)
src/ivoc/ocbox.cpp	22.22% <0.00%> (ø)
src/ivoc/ocdeck.cpp	13.87% <0.00%> (ø)
src/ivoc/pwman.cpp	2.20% <0.00%> (ø)
... and 15 more

📣 Codecov can now indicate which changes are the most critical in Pull Requests. Learn more

[azure-pipelines]

✔️ 18456416f27b8e0d0bf70b8c9c772d1b5b21c168 -> Azure artifacts URL

[azure-pipelines]

✔️ 58e8ec65c83dd459a96d8ac564460ce802cad037 -> Azure artifacts URL

[azure-pipelines]

✔️ dfdd0a246f99810402323806b92767293a8bdb6b -> Azure artifacts URL

[azure-pipelines]

✔️ ae699d5 -> Azure artifacts URL

[alexsavulescu]

LGTM

[azure-pipelines]

✔️ 12530f3 -> Azure artifacts URL

[azure-pipelines]

✔️ 655d2b1 -> Azure artifacts URL

[olupton]

LGTM, thanks for the finishing touches @alexsavulescu.

[olupton]

✔️ 655d2b1 -> Azure artifacts URL

I checked this URL in https://bbpgitlab.epfl.ch/hpc/personal/neuron-gpu-wheel-testing/-/pipelines/63923 using the test_wheels.sh script with the GPU wheel on BB5.

[ohm314]

lgtm