Widen tanh_fast signature

[mcabbott]

As noted here #371 (comment) defining as a fallback only tanh_fast(::Real) causes problems for Flux right now. And tanh of course makes sense for complex numbers.

But really, all the other activation functions only make sense for real numbers, since they often compare x>0 etc. In the interests of sanity and sensible guard-rails, they should probably all have signature ::Real not ::Any. But can't be changed just yet.

[mcabbott]

CI fails on unrelated things which worked yesterday?

Test Summary:        | Pass  Total
223
Activation Functions | 1329   1329
224
Test Summary:          | Pass  Total
225
Batched Multiplication | 3327   3327
226
[ Info: Skipping Convolutional fuzzing tests, set NNLIB_TEST_FUZZING=true to run them
227
[ Info: Skipping Depthwise Convolutional fuzzing tests, set NNLIB_TEST_FUZZING=true to run them
228
Grouped Convolutions: Error During Test at /home/runner/work/NNlib.jl/NNlib.jl/test/conv.jl:659
229
  Got exception outside of a @test
230
  type Nothing has no field method
231
  Stacktrace:
232
    [1] getproperty
233
      @ ./Base.jl:42 [inlined]
234
    [2] matching_cr_sig(t::IRTools.Inner.Meta, s::Nothing)
235
      @ Zygote ~/.julia/packages/Zygote/umM0L/src/compiler/chainrules.jl:72
236
    [3] has_chain_rrule(T::Type)
237
      @ Zygote ~/.julia/packages/Zygote/umM0L/src/compiler/chainrules.jl:54
238

[darsnack]

Getting the same issues locally on a completely separate project (getting Metalhead pre-training running).

[darsnack]

The only thing I can see that has changed in this timeframe is ChainRules.jl/ChainRulesCore.jl but those changes seem completely orthogonal to the error.

[mcabbott]

Thanks, that's useful. If just pushed an upper bound to exclude ChainRules v1.18.0, today's version, just to see?

Except that I don't know the syntax it seems...

[mcabbott]

This probably shouldn't wait too long, as the current state breaks Flux's tests.

[darsnack]

Both this and FluxML/Flux.jl#1830 are okay with me, though I think this is safer to merge quickly and get tests up again.