Fix CairoMakie erroring when recipes return lists of PlotSpec

[asinghvi17]

Description

CairoMakie suffered from a method ambiguity when a convert_arguments returned a list of plotspecs using the new SpecApi. This PR eliminates that method ambiguity and adds a reference test for it, so we know that all backends support plotlists!

I will probably need some help updating the reference images though!

Type of change

Delete options that do not apply:

• Bug fix (non-breaking change which fixes an issue)

Checklist

• Added an entry in NEWS.md (for new features and breaking changes)
• Added or changed relevant sections in the documentation
• Added unit tests for new algorithms, conversion methods, etc.
• Added reference image tests for new plotting functions, recipes, visual options, etc.

[MakieBot]

Compile Times benchmark

Note, that these numbers may fluctuate on the CI servers, so take them with a grain of salt. All benchmark results are based on the mean time and negative percent mean faster than the base branch. Note, that GLMakie + WGLMakie run on an emulated GPU, so the runtime benchmark is much slower. Results are from running:

using_time = @ctime using Backend
# Compile time
create_time = @ctime fig = scatter(1:4; color=1:4, colormap=:turbo, markersize=20, visible=true)
display_time = @ctime Makie.colorbuffer(display(fig))
# Runtime
create_time = @benchmark fig = scatter(1:4; color=1:4, colormap=:turbo, markersize=20, visible=true)
display_time = @benchmark Makie.colorbuffer(fig)

	using	create	display	create	display
GLMakie	3.38s (3.34, 3.42) 0.03+-	383.30ms (376.53, 411.47) 12.82+-	476.92ms (462.10, 512.97) 21.19+-	7.21ms (6.99, 7.45) 0.15+-	25.37ms (25.26, 25.50) 0.11+-
master	3.37s (3.32, 3.43) 0.04+-	388.63ms (375.25, 397.52) 8.36+-	469.19ms (464.26, 474.68) 3.84+-	7.17ms (7.03, 7.29) 0.10+-	25.38ms (25.22, 25.54) 0.11+-
evaluation	1.00x invariant, 0.0s (0.09d, 0.87p, 0.04std)	1.01x invariant, -5.32ms (-0.49d, 0.38p, 10.59std)	0.98x invariant, 7.73ms (0.51d, 0.38p, 12.51std)	0.99x invariant, 0.05ms (0.38d, 0.50p, 0.13std)	1.00x invariant, -0.01ms (-0.09d, 0.87p, 0.11std)
CairoMakie	3.02s (2.99, 3.05) 0.02+-	318.95ms (316.90, 321.52) 1.76+-	140.74ms (139.39, 141.40) 0.66+-	7.16ms (7.09, 7.21) 0.04+-	604.91μs (598.23, 615.66) 7.02+-
master	3.03s (2.96, 3.14) 0.07+-	319.00ms (314.59, 322.21) 2.47+-	141.33ms (139.76, 144.04) 1.45+-	7.17ms (7.08, 7.28) 0.07+-	606.17μs (602.15, 609.42) 2.46+-
evaluation	1.01x invariant, -0.02s (-0.31d, 0.58p, 0.04std)	1.00x invariant, -0.04ms (-0.02d, 0.97p, 2.12std)	1.00x invariant, -0.59ms (-0.53d, 0.35p, 1.06std)	1.00x invariant, -0.01ms (-0.13d, 0.81p, 0.06std)	1.00x invariant, -1.25μs (-0.24d, 0.67p, 4.74std)
WGLMakie	3.75s (3.67, 3.82) 0.07+-	333.36ms (318.98, 369.55) 18.22+-	9.20s (8.89, 9.83) 0.35+-	10.05ms (9.29, 12.57) 1.13+-	70.94ms (68.11, 83.09) 5.43+-
master	3.74s (3.67, 3.80) 0.05+-	328.30ms (318.60, 336.90) 7.80+-	9.06s (8.97, 9.21) 0.10+-	9.50ms (9.25, 9.76) 0.18+-	73.73ms (68.51, 78.29) 3.80+-
evaluation	1.00x invariant, 0.02s (0.26d, 0.63p, 0.06std)	0.98x invariant, 5.05ms (0.36d, 0.52p, 13.01std)	0.98x invariant, 0.14s (0.54d, 0.35p, 0.22std)	0.95x noisy🤷‍♀️, 0.55ms (0.68d, 0.25p, 0.65std)	1.04x invariant, -2.79ms (-0.60d, 0.29p, 4.61std)

[asinghvi17]

Hey, just want to bump this - would be nice to get it out there!

[SimonDanisch]

On master the test case you added works for me.
Which Julia version did you try?
Also, the test case should be more like:

struct PlotlistTestType end

function Makie.convert_arguments(::Type{<: Makie.Plot}, obj::PlotlistTestType)
    return [
        Makie.SpecApi.Lines([0, 1], [0, 1]),
        Makie.SpecApi.Scatter([0.5], [0.5]),
    ]
end
plot(PlotlistTestType())

Or was there a good reason to define convert_arguments for Lines?

[asinghvi17]

Huh! Yeah I just tested with latest master and this was not an issue there...maybe my local env was misconfigured? Will add the test you suggested at a later point.

About the lines thing: my usecase was specifically allowing plots to "pass-through", so lines seemed like the best candidate just to make sure nothing got in the way there.