First off, that’s impressive. Only thing I would suggest is commenting out multiple lines between #= and =# instead of # leading each line to make copy-pasting convenient.
Second, I tried @code_warntype right out the gate before any execution, and it appears as type-stable as your reports after benchmarks. However, if we Cthulhu.@descend deeper, we run into recursion with changing argument types:
305 all(f::Main.Euler2D_MWE.var"#1#2"{SClosedPolygon{4, Float64}}::Function, a::SVector{4, SVector{2, Float64}}::StaticArray; dims::Core.Const(Colon())=:)::Bool = _mapreduce(x->f(x)::Bool, &::Core.Const(&), dims::Core.Const(Colon()), true, Size(a::SVector{4, SVector{2, Float64}})::Core.Const(Size(4,)), a::SVector{4, SVector{2, Float64}})
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Size(a::SVector{4, SVector{2, Float64}})
• _mapreduce(x->f(x)::Bool, &::Core.Const(&), dims::Core.Const(Colon()), true, Size(a::SVector{4, SVector{2, Float64}})::Core.Const(Size(4,)), a::SVec…
↩
_mapreduce(args::Vararg{Any, N}) where N @ StaticArrays C:\Users\Benny\.julia\packages\StaticArrays\DsPgf\src\mapreduce.jl:153
┌ Warning: Inference terminated in an incomplete state due to argument-type changes during recursion
despite the ultimate return value of all being inferred as Bool. The implied recursion isn’t clear because some metaprogramming obscured calls on top of the compromised type information; in other words, it’s hard to pick which lines to manually descend further.
Fortunately, `JET.@reportopt` automatically ''descends'' into all the calls to filter out instability and dispatch issues, and it spots an explicit recursion becoming unoptimized and runtime-dispatched. It seems to corroborate your comment about `all(Base.Fix2(...),...)` being a potential issue for `point_inside_strict`, a function called in the input function for `all` in the benchmarked function.
julia> @report_opt Euler2D_MWE.is_cell_contained_by(test_cell, test_poly1)
═════ 8 possible errors found ═════
┌ is_cell_contained_by(cell1::TangentQuadCell_MWE{Float64, 3, 12}, poly::SClosedPolygon{4, Float64}) @ Main.Euler2D_MWE ./REPL[7]:35
│┌ all(f::Main.Euler2D_MWE.var"#1#2"{SClosedPolygon{4, Float64}}, a::SVector{4, SVector{2, Float64}}) @ StaticArrays C:\Users\Benny\.julia\packages\StaticArrays\DsPgf\src\mapreduce.jl:305
││┌ all(f::Main.Euler2D_MWE.var"#1#2"{SClosedPolygon{4, Float64}}, a::SVector{4, SVector{2, Float64}}; dims::Colon) @ StaticArrays C:\Users\Benny\.julia\packages\StaticArrays\DsPgf\src\mapreduce.jl:305
│││┌ _mapreduce(::StaticArrays.var"#214#215"{…}, ::typeof(&), ::Colon, ::Bool, ::Size{…}, ::SVector{…}) @ StaticArrays C:\Users\Benny\.julia\packages\StaticArrays\DsPgf\src\mapreduce.jl:153
││││┌ _mapfoldl(f::StaticArrays.var"#214#215"{…}, op::typeof(&), dims::Colon, init::Bool, ::Size{…}, a::SVector{…}) @ StaticArrays C:\Users\Benny\.julia\packages\StaticArrays\DsPgf\src\mapreduce.jl:180
│││││┌ (::StaticArrays.var"#214#215"{Main.Euler2D_MWE.var"#1#2"{SClosedPolygon{4, Float64}}})(x::SVector{2, Float64}) @ StaticArrays C:\Users\Benny\.julia\packages\StaticArrays\DsPgf\src\mapreduce.jl:305
││││││┌ (::Main.Euler2D_MWE.var"#1#2"{SClosedPolygon{4, Float64}})(pt::SVector{2, Float64}) @ Main.Euler2D_MWE ./REPL[7]:36
│││││││┌ point_inside_strict(poly::SClosedPolygon{4, Float64}, pt::SVector{2, Float64}) @ Main.PlanePolygons_MWE ./REPL[6]:71
││││││││┌ all(f::Base.Fix2{…}, a::SVector{…}) @ StaticArrays C:\Users\Benny\.julia\packages\StaticArrays\DsPgf\src\mapreduce.jl:305
│││││││││┌ all(f::Base.Fix2{…}, a::SVector{…}; dims::Colon) @ StaticArrays C:\Users\Benny\.julia\packages\StaticArrays\DsPgf\src\mapreduce.jl:305
││││││││││┌ _mapreduce(::StaticArrays.var"#214#215", ::typeof(&), ::Colon, ::Bool, ::Size{…}, ::SVector{…}) @ StaticArrays C:\Users\Benny\.julia\packages\StaticArrays\DsPgf\src\mapreduce.jl:153
│││││││││││ runtime dispatch detected: StaticArrays._mapfoldl(%1::StaticArrays.var"#214#215", &, Colon(), %2::Bool, [quote]::Size{(4,)}, %3::SVector{4, Main.PlanePolygons_MWE.Line{Float64}})::Bool
││││││││││└────────────────────
│││││││││┌ all(f::Base.Fix2{…}, a::SVector{…}; dims::Colon) @ StaticArrays C:\Users\Benny\.julia\packages\StaticArrays\DsPgf\src\mapreduce.jl:305
││││││││││ failed to optimize due to recursion: StaticArrays.var"#all#213"(::Colon, ::typeof(all), ::Base.Fix2{…}, ::SVector{…})
│││││││││└────────────────────
││││││││┌ all(f::Base.Fix2{…}, a::SVector{…}) @ StaticArrays C:\Users\Benny\.julia\packages\StaticArrays\DsPgf\src\mapreduce.jl:305
│││││││││ failed to optimize due to recursion: all(::Base.Fix2{…}, ::SVector{…})
││││││││└────────────────────
│││││││┌ point_inside_strict(poly::SClosedPolygon{4, Float64}, pt::SVector{2, Float64}) @ Main.PlanePolygons_MWE ./REPL[6]:70
││││││││ failed to optimize due to recursion: Main.PlanePolygons_MWE.point_inside_strict(::SClosedPolygon{4, Float64}, ::SVector{2, Float64})
│││││││└────────────────────
││││││┌ (::Main.Euler2D_MWE.var"#1#2"{SClosedPolygon{4, Float64}})(pt::SVector{2, Float64}) @ Main.Euler2D_MWE ./REPL[7]:36
│││││││ failed to optimize due to recursion: (::Main.Euler2D_MWE.var"#1#2"{SClosedPolygon{4, Float64}})(::SVector{2, Float64})
││││││└────────────────────
│││││┌ (::StaticArrays.var"#214#215"{Main.Euler2D_MWE.var"#1#2"{SClosedPolygon{4, Float64}}})(x::SVector{2, Float64}) @ StaticArrays C:\Users\Benny\.julia\packages\StaticArrays\DsPgf\src\mapreduce.jl:305
││││││ failed to optimize due to recursion: (::StaticArrays.var"#214#215"{Main.Euler2D_MWE.var"#1#2"{SClosedPolygon{4, Float64}}})(::SVector{2, Float64})
│││││└────────────────────
││││┌ _mapfoldl(f::StaticArrays.var"#214#215"{…}, op::typeof(&), dims::Colon, init::Bool, ::Size{…}, a::SVector{…}) @ StaticArrays C:\Users\Benny\.julia\packages\StaticArrays\DsPgf\src\mapreduce.jl:155
│││││ failed to optimize due to recursion: StaticArrays._mapfoldl(::StaticArrays.var"#214#215"{…}, ::typeof(&), ::Colon, ::Bool, ::Size{…}, ::SVector{…})
││││└────────────────────
│││┌ _mapreduce(::StaticArrays.var"#214#215"{…}, ::typeof(&), ::Colon, ::Bool, ::Size{…}, ::SVector{…}) @ StaticArrays C:\Users\Benny\.julia\packages\StaticArrays\DsPgf\src\mapreduce.jl:153
││││ failed to optimize due to recursion: StaticArrays._mapreduce(::StaticArrays.var"#214#215"{…}, ::typeof(&), ::Colon, ::Bool, ::Size{…}, ::SVector{…})
│││└────────────────────
These reports persist after the 0 allocation benchmark. These reports also show up if run fresh after your MWE completed the 0 allocation benchmark. Like @code_warntype etc, these packages seem to perform type inference fresh, so it’s still possible it diverges from the actually compiled code. Not great in the exceptional cases like these where state matters.