use the preference system for nan safe mode

[KristofferC]

No description provided.

[KristofferC]

Closes #181 I think

[codecov-commenter]

Codecov Report

Merging #539 (7639166) into master (80a13d9) will decrease coverage by 0.13%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #539      +/-   ##
==========================================
- Coverage   84.90%   84.76%   -0.14%     
==========================================
  Files           9        9              
  Lines         828      827       -1     
==========================================
- Hits          703      701       -2     
- Misses        125      126       +1     

Impacted Files	Coverage Δ
src/prelude.jl	37.50% <ø> (ø)
src/dual.jl	72.43% <0.00%> (-0.36%)	⬇️
src/apiutils.jl	100.00% <0.00%> (ø)

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[devmotion]

What's holding back this PR? It would be great if switching to NaN-safe mode would be easier.

[KristofferC]

Nothing really. Someone to review it perhaps.

[devmotion]

My knowledge about Preferences is only based on its README, but according to this it looks good to me. Seems to match the instructions in https://github.com/JuliaPackaging/Preferences.jl#conditional-loading.

[chriselrod]

How does one @set_preferences!?

[devmotion]

As a user you would use set_preferences!: https://juliadiff.org/ForwardDiff.jl/dev/user/advanced/#Fixing-NaN/Inf-Issues

[chriselrod]

julia> using ForwardDiff, Preferences

julia> set_preferences!(ForwardDiff, "nansafe_mode" => true)

Ah, thanks!