Bug report: allocating custom abstract types

[wnederpel]

First of all: cool package and thanks for your work!

While I was working with the package I encountered an error starting with
"Please submit a bug report with steps to reproduce this fault, and any error messages that follow (in their entirety). Thanks."
so here is that bug report.

I wanted to allocate some memory for an array with an abstract eltype. Here is a minimal (not) working example:

using Bumper

abstract type MyType end

struct MyStruct <: MyType
    x::Int
end

Base.sizeof(::Type{MyType}) = sizeof(Int)

@no_escape begin
    foo_arr = @alloc(MyType, 10)
    println(foo_arr)
end

I suppose the answer might be 'you cannot define sizeof for your abstract type and expect things to work', but I wanted to open this bug report anyway as requested.

Here is the full stack trace:

Please submit a bug report with steps to reproduce this fault, and any error messages that follow (in their entirety). Thanks.
Exception: EXCEPTION_ACCESS_VIOLATION at 0x15f21dd2f5e -- _show_default at .\show.jl:465
in expression starting at C:\Users\wolf.nederpel\hive\intsect\scripts\random_julia_test.jl:11
_show_default at .\show.jl:465
show_default at .\show.jl:462 [inlined]
show at .\show.jl:457 [inlined]
show_delim_array at .\show.jl:1346
show_delim_array at .\show.jl:1335 [inlined]
show_vector at .\arrayshow.jl:530
show_vector at .\arrayshow.jl:515 [inlined]
show at .\arrayshow.jl:486 [inlined]
print at .\strings\io.jl:35
print at .\strings\io.jl:46
println at .\strings\io.jl:75
unknown function (ip: 0000015f21dd4f1f)
println at .\coreio.jl:4
unknown function (ip: 0000015f21dd2bcb)
jl_apply at C:/workdir/src\julia.h:1982 [inlined]
do_call at C:/workdir/src\interpreter.c:126
eval_value at C:/workdir/src\interpreter.c:223
eval_body at C:/workdir/src\interpreter.c:489
jl_interpret_toplevel_thunk at C:/workdir/src\interpreter.c:775
jl_toplevel_eval_flex at C:/workdir/src\toplevel.c:934
jl_toplevel_eval_flex at C:/workdir/src\toplevel.c:877
ijl_toplevel_eval at C:/workdir/src\toplevel.c:943 [inlined]
ijl_toplevel_eval_in at C:/workdir/src\toplevel.c:985
eval at .\boot.jl:385 [inlined]
include_string at .\loading.jl:2070
_include at .\loading.jl:2130
include at .\client.jl:489
unknown function (ip: 0000015f21dc916b)
jl_apply at C:/workdir/src\julia.h:1982 [inlined]
do_call at C:/workdir/src\interpreter.c:126
eval_value at C:/workdir/src\interpreter.c:223
eval_stmt_value at C:/workdir/src\interpreter.c:174 [inlined]
eval_body at C:/workdir/src\interpreter.c:635
jl_interpret_toplevel_thunk at C:/workdir/src\interpreter.c:775
jl_toplevel_eval_flex at C:/workdir/src\toplevel.c:934
jl_toplevel_eval_flex at C:/workdir/src\toplevel.c:877
ijl_toplevel_eval at C:/workdir/src\toplevel.c:943 [inlined]
ijl_toplevel_eval_in at C:/workdir/src\toplevel.c:985
eval at .\boot.jl:385 [inlined]
eval_user_input at C:\workdir\usr\share\julia\stdlib\v1.10\REPL\src\REPL.jl:150
repl_backend_loop at C:\workdir\usr\share\julia\stdlib\v1.10\REPL\src\REPL.jl:246
#start_repl_backend#46 at C:\workdir\usr\share\julia\stdlib\v1.10\REPL\src\REPL.jl:231
start_repl_backend at C:\workdir\usr\share\julia\stdlib\v1.10\REPL\src\REPL.jl:228
#run_repl#59 at C:\workdir\usr\share\julia\stdlib\v1.10\REPL\src\REPL.jl:389
run_repl at C:\workdir\usr\share\julia\stdlib\v1.10\REPL\src\REPL.jl:375
jfptr_run_repl_95895.1 at C:\Users\wolf.nederpel\AppData\Local\Programs\Julia-1.10.0\lib\julia\sys.dll (unknown line)
#1013 at .\client.jl:432
jfptr_YY.1013_86694.1 at C:\Users\wolf.nederpel\AppData\Local\Programs\Julia-1.10.0\lib\julia\sys.dll (unknown line)
jl_apply at C:/workdir/src\julia.h:1982 [inlined]
jl_f__call_latest at C:/workdir/src\builtins.c:812
#invokelatest#2 at .\essentials.jl:887 [inlined]
invokelatest at .\essentials.jl:884 [inlined]
run_main_repl at .\client.jl:416
exec_options at .\client.jl:333
_start at .\client.jl:552
jfptr__start_86719.1 at C:\Users\wolf.nederpel\AppData\Local\Programs\Julia-1.10.0\lib\julia\sys.dll (unknown line)
jl_apply at C:/workdir/src\julia.h:1982 [inlined]
true_main at C:/workdir/src\jlapi.c:582
jl_repl_entrypoint at C:/workdir/src\jlapi.c:731
mainCRTStartup at C:/workdir/cli\loader_exe.c:58
BaseThreadInitThunk at C:\windows\System32\KERNEL32.DLL (unknown line)
RtlUserThreadStart at C:\windows\SYSTEM32\ntdll.dll (unknown line)
Allocations: 635700 (Pool: 634725; Big: 975); GC: 1

[MasonProtter]

Hi @wnederpel yeah this is not something that Bumper can support, but it should fail in a more graceful way, I'll try to fix this soon.

[MilesCranmer]

@MasonProtter instead, could @alloc just fall back to a normal array allocation?

If I am writing a function for generic input type Vector{T}, right now, I have to write two separate methods:

1. one for Bumper-compatible types, and
2. one for everything else.

But the code itself is basically the same. This leads to dangerous “shotgun edits” where I have to update the code in both places whenever I add a feature.

Can Bumper.jl itself just do a regular allocation if the type is not concrete?

You could then have an @alloc(…, strict=true) to disable fallbacks.

[MasonProtter]

Yeah that sounds pretty reasonable to do.