Conversion to pointer not defined for `Base.ReinterpretArray` on v1.11 and above

[jishnub]

I suspect this might have been discussed before, but I couldn't find it.

julia> VERSION
v"1.10.4"

julia> Base.unsafe_convert(Ptr{Float64}, reinterpret(Float64, ComplexF64[1.0]))
Ptr{Float64} @0x00007fc192837e20

but on v"1.11.0-beta2"

julia> Base.unsafe_convert(Ptr{Float64}, reinterpret(Float64, ComplexF64[1.0]))
ERROR: conversion to pointer not defined for Base.ReinterpretArray{Float64, 1, ComplexF64, Vector{ComplexF64}, false}
Stacktrace:
 [1] error(s::String)
   @ Base ./error.jl:35
 [2] unsafe_convert(::Type{Ptr{Float64}}, a::Base.ReinterpretArray{Float64, 1, ComplexF64, Vector{ComplexF64}, false})
   @ Base ./pointer.jl:68
 [3] top-level scope
   @ REPL[1]:1

This occurs in ccall operations when trying to pass a ReinterpretArray to a C function (e.g. in https://github.com/JuliaAstro/FITSIO.jl/actions/runs/8897458859/job/24432396258?pr=196). The selevant snippet of the stacktrace is

     [1] error(s::String)
      @ Base ./error.jl:44
    [2] unsafe_convert(::Type{Ptr{Float64}}, a::Base.ReinterpretArray{Float64, 1, ComplexF64, Vector{ComplexF64}, false})
      @ Base ./pointer.jl:68
    [3] unsafe_convert(::Type{Ptr{Nothing}}, a::Base.ReinterpretArray{Float64, 1, ComplexF64, Vector{ComplexF64}, false})
      @ Base ./pointer.jl:66
    [4] fits_write_pix(f::FITSFile, fpixel::Tuple{Int64}, nelements::Int64, data::Base.ReinterpretArray{Float64, 1, ComplexF64, Vector{ComplexF64}, false})
      @ CFITSIO ~/.julia/packages/CFITSIO/zfTMn/src/CFITSIO.jl:1219
    [5] fits_write_pix(f::FITSFile, data::Base.ReinterpretArray{Float64, 1, ComplexF64, Vector{ComplexF64}, false})
      @ CFITSIO ~/.julia/packages/CFITSIO/zfTMn/src/CFITSIO.jl:1244

Here, the ccall in fits_write_pix on line 1219 takes the form

ccall(
        (:ffppxll, libcfitsio),
        Cint,
        (Ptr{Cvoid}, Cint, Ptr{NTuple{N,Int64}}, Int64, Ptr{Cvoid}, Ref{Cint}),
        f.ptr,
        cfitsio_typecode(eltype(data)),
        fpixelr,
        nelements,
        data,
        status,
    )

where data is a ReinterpretArray array.

Some other info:

julia> versioninfo()
Julia Version 1.11.0-beta2
Commit edb3c92d6a6 (2024-05-29 09:37 UTC)
Build Info:
  Official https://julialang.org/ release
Platform Info:
  OS: Linux (x86_64-linux-gnu)
  CPU: 8 × 11th Gen Intel(R) Core(TM) i5-1135G7 @ 2.40GHz
  WORD_SIZE: 64
  LLVM: libLLVM-16.0.6 (ORCJIT, tigerlake)
Threads: 1 default, 0 interactive, 1 GC (on 8 virtual cores)
Environment:
  LD_LIBRARY_PATH = :/usr/lib/x86_64-linux-gnu/gtk-3.0/modules
  JULIA_EDITOR = subl

and julia is installed through juliaup.

[nsajko]

xref #51962?

[jishnub]

It's probably a different issue, as cconvert is defined for a ReinterpretArray and a pointer may be obtained from it, but a direct unsafe_convert isn't defined anymore. It may simply be a matter of redefining the method, but I wonder if it was removed for a reason.

[vchuravy]

I ran into this just now as well.

 Error: Error in render loop!
│   exception = conversion to pointer not defined for Base.ReinterpretArray{ColorTypes.RGB{Float32}, 2, Float32, Array{Float32, 3}, true}
└ @ NeuralGraphicsGL ~/.julia/packages/NeuralGraphicsGL/5ny5N/src/NeuralGraphicsGL.jl:285

Stacktrace:
  [1] error(s::String)
    @ Base ./error.jl:35
  [2] unsafe_convert(::Type{Ptr{ColorTypes.RGB{Float32}}}, a::Base.ReinterpretArray{ColorTypes.RGB{Float32}, 2, Float32, Array{Float32, 3}, true})
    @ Base ./pointer.jl:68
  [3] unsafe_convert(::Type{Ptr{Nothing}}, a::Base.ReinterpretArray{ColorTypes.RGB{Float32}, 2, Float32, Array{Float32, 3}, true})
    @ Base ./pointer.jl:66
  [4] glTexImage2D(target::UInt32, level::Int64, internalformat::UInt32, width::UInt32, height::UInt32, border::Int64, format::UInt32, type_::UInt32, pixels::Base.ReinterpretArray{ColorTypes.RGB{Float32}, 2, Float32, Array{Float32, 3}, true})
    @ ModernGL ~/.julia/packages/ModernGL/yNrOu/src/functionloading.jl:64
  [5] macro expansion
    @ ~/.julia/packages/NeuralGraphicsGL/5ny5N/src/NeuralGraphicsGL.jl:72 [inlined]
  [6] set_data!(t::NeuralGraphicsGL.Texture, data::Base.ReinterpretArray{ColorTypes.RGB{Float32}, 2, Float32, Array{Float32, 3}, true})
    @ NeuralGraphicsGL ~/.julia/packages/NeuralGraphicsGL/5ny5N/src/texture.jl:89
  [7] set_data!
    @ ~/.julia/packages/NeuralGraphicsGL/5ny5N/src/quad.jl:77 [inlined]
  [8] render!(ngui::NerfGUI.NGUI)
    @ NerfGUI ~/src/NerfGUI/src/NerfGUI.jl:206
  [9] loop!(ngui::NerfGUI.NGUI)
    @ NerfGUI ~/src/NerfGUI/src/NerfGUI.jl:446
 [10] #32
    @ ~/src/NerfGUI/src/NerfGUI.jl:213 [inlined]
 [11] render_loop(draw_function::NerfGUI.var"#32#33"{NerfGUI.NGUI}, c::NeuralGraphicsGL.Context; destroy_context::Bool)
    @ NeuralGraphicsGL ~/.julia/packages/NeuralGraphicsGL/5ny5N/src/NeuralGraphicsGL.jl:281
 [12] render_loop
    @ ~/.julia/packages/NeuralGraphicsGL/5ny5N/src/NeuralGraphicsGL.jl:278 [inlined]
 [13] launch!
    @ ~/src/NerfGUI/src/NerfGUI.jl:211 [inlined]
 [14] main()
    @ NerfGUI ~/src/NerfGUI/src/NerfGUI.jl:487

Weirdly enough there is no direct call to unsafe_convert in sight.

https://github.com/JuliaGL/ModernGL.jl/blob/90200d81d1d0194f9855163524ecb499b8f2c881/src/functionloading.jl#L64

julia> @macroexpand ModernGL.@glfunc glTexImage2D(target::GLenum, level::GLint, internalformat::GLint, width::GLsizei, height::GLsizei, border::GLint, format::GLenum, type_::GLenum, pixels::Ptr{Cvoid})::Cvoid
quote
    #= /home/vchuravy/.julia/packages/ModernGL/yNrOu/src/functionloading.jl:59 =#
    const var"##glTexImage2D_func_pointer#231" = Ref{Ptr{Cvoid}}(C_NULL)
    #= /home/vchuravy/.julia/packages/ModernGL/yNrOu/src/functionloading.jl:60 =#
    function glTexImage2D(target, level, internalformat, width, height, border, format, type_, pixels)
        #= /home/vchuravy/.julia/packages/ModernGL/yNrOu/src/functionloading.jl:60 =#
        #= /home/vchuravy/.julia/packages/ModernGL/yNrOu/src/functionloading.jl:61 =#
        if var"##glTexImage2D_func_pointer#231"[]::Ptr{Cvoid} == C_NULL
            #= /home/vchuravy/.julia/packages/ModernGL/yNrOu/src/functionloading.jl:62 =#
            var"##glTexImage2D_func_pointer#231"[]::Ptr{Cvoid} = getprocaddress_e("glTexImage2D")
        end
        #= /home/vchuravy/.julia/packages/ModernGL/yNrOu/src/functionloading.jl:64 =#
        result = ccall(var"##glTexImage2D_func_pointer#231"[]::Ptr{Cvoid}, Cvoid, (GLenum, GLint, GLint, GLsizei, GLsizei, GLint, GLenum, GLenum, Ptr{Cvoid}), target, level, internalformat, width, height, border, format, type_, pixels)
        #= /home/vchuravy/.julia/packages/ModernGL/yNrOu/src/functionloading.jl:65 =#
        ()
        #= /home/vchuravy/.julia/packages/ModernGL/yNrOu/src/functionloading.jl:66 =#
        result
    end
    #= /home/vchuravy/.julia/packages/ModernGL/yNrOu/src/functionloading.jl:68 =#
    export glTexImage2D
end

-- edit:

cconvert

julia/base/reinterpretarray.jl

Line 375 in 8791d54

cconvert(::Type{Ptr{T}}, a::ReinterpretArray{T,N,S} where N) where {T,S} = cconvert(Ptr{S}, a.parent)

is only defined for Ptr{T}