EigenSolvers as extensions

[pablosanjose]

Closes #297

We introduce extensions for LinearMaps, ArnoldiMethod, KrylovKit and Arpack.

This has revealed yet another issue with FunctionWrappers.jl, similar to #235, but not quite the same. When attempting to call spectrum(h; solver = ...) with an unloaded extension for the solver, it would error as expected. Then, after loading the relevant package, calling spectrum again would yield a weird error such as

julia> spectrum(h, (0,), solver = ES.ShiftInvert(ES.ArnoldiMethod(nev = 4), 0))
ERROR: TypeError: in cfunction, expected Union{}, got a value of type LinearAlgebra.Eigen{ComplexF64, ComplexF64, Matrix{ComplexF64}, Vector{ComplexF64}}
Stacktrace:
 [1] macro expansion
   @ ~/.julia/packages/FunctionWrappers/Q5cBx/src/FunctionWrappers.jl:137 [inlined]
 [2] do_ccall
   @ ~/.julia/packages/FunctionWrappers/Q5cBx/src/FunctionWrappers.jl:125 [inlined]
 [3] FunctionWrapper
   @ ~/.julia/packages/FunctionWrappers/Q5cBx/src/FunctionWrappers.jl:144 [inlined]
 [4] AppliedEigenSolver
   @ ~/.julia/dev/Quantica/src/types.jl:1716 [inlined]
 [5] spectrum(h::Quantica.ParametricHamiltonian{Float64, 1, 1, ComplexF64, Tuple{…}}, φs::Tuple{Int64}; solver::Quantica.EigenSolvers.ShiftInvert{Int64, Quantica.EigenSolvers.ArnoldiMethod{…}}, transform::Missing, kw::@Kwargs{})
   @ Quantica ~/.julia/dev/Quantica/src/bands.jl:11
 [6] top-level scope
   @ REPL[5]:1

This likely stems from FunctionWrappers' issues with the world age system, and is, interestingly, fixed by the same approach as #235. However this impacts also aarch64 (macos) and Julia 1.11, unlike #235, so it seems to be more general.

We have implemented a cheaper fix, trying for the moment to avoid excising FunctionWrappers altogether (which, admittedly, improves compile and runtime performance in Quantica). It consists of always running the wrapped eigensolver with a dryrun=true option to make it almost free, but force it to compile.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.55%. Comparing base (fc93e65) to head (e1b1ddc).

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Additional details and impacted files

@@            Coverage Diff             @@
##           master     #298      +/-   ##
==========================================
- Coverage   92.61%   92.55%   -0.07%     
==========================================
  Files          37       37              
  Lines        6299     6270      -29     
==========================================
- Hits         5834     5803      -31     
- Misses        465      467       +2     

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[pablosanjose]

The test failures on nightly are unrelated, and caused by CairoMakie, so they are not blocking.