infinite loop in C code when trying to add a method

[nsajko]

MWE:

struct Frac{T} end
Base.:+(a::Frac{<:T},b::Union{Number,T}) where {T} = nothing
Base.:+(b::Union{Number,T},a::Frac{<:T}) where {T} = nothing

FTR this makes it impossible to compile LaurentPolynomials.jl.

Version info:

Julia Version 1.12.0-DEV.555
Commit 6c17db1ba12 (2024-05-17 23:51 UTC)
Build Info:
  Official https://julialang.org/ release
Platform Info:
  OS: Linux (x86_64-linux-gnu)
  CPU: 8 × AMD Ryzen 3 5300U with Radeon Graphics
  WORD_SIZE: 64
  LLVM: libLLVM-17.0.6 (ORCJIT, znver2)
Threads: 1 default, 0 interactive, 1 GC (on 8 virtual cores)

[nsajko]

When trying to precompile LaurentPolynomials.jl:

julia> using LaurentPolynomials
Precompiling LaurentPolynomials...
^C Interrupted: Exiting precompilation...
Info [ Info: Waiting for another process (pid: 497792) to finish precompiling LaurentPolynomials [10b2801c-d482-41ed-a506-4a825c59e3da]. Pidfile: /home/nsajko/.julia/compiled/v1.12/LaurentPolynomials/9eoeD_u6Ef1.ji.pidfile
Given LaurentPolynomials was explicitly requested, output will be shown live 

[497799] signal 2: Interrupt
[ Info: Precompiling LaurentPolynomials [10b2801c-d482-41ed-a506-4a825c59e3da] 
in expression starting at /home/nsajko/.julia/packages/LaurentPolynomials/Vje2Z/src/LaurentPolynomials.jl:901
jl_has_bound_typevars at /cache/build/builder-amdci5-3/julialang/julia-master/src/jltypes.c:221
finish_unionall at /cache/build/builder-amdci5-3/julialang/julia-master/src/subtype.c:3015
intersect_unionall_ at /cache/build/builder-amdci5-3/julialang/julia-master/src/subtype.c:3194
intersect_unionall at /cache/build/builder-amdci5-3/julialang/julia-master/src/subtype.c:3265
intersect at /cache/build/builder-amdci5-3/julialang/julia-master/src/subtype.c:3865
intersect_all at /cache/build/builder-amdci5-3/julialang/julia-master/src/subtype.c:4126
jl_type_intersection_env_s at /cache/build/builder-amdci5-3/julialang/julia-master/src/subtype.c:4348
jl_typemap_intersection_node_visitor at /cache/build/builder-amdci5-3/julialang/julia-master/src/typemap.c:543
jl_typemap_intersection_visitor at /cache/build/builder-amdci5-3/julialang/julia-master/src/typemap.c:812
jl_typemap_intersection_memory_visitor at /cache/build/builder-amdci5-3/julialang/julia-master/src/typemap.c:500
jl_typemap_intersection_visitor at /cache/build/builder-amdci5-3/julialang/julia-master/src/typemap.c:802
get_intersect_matches at /cache/build/builder-amdci5-3/julialang/julia-master/src/gf.c:1567 [inlined]
jl_method_table_activate at /cache/build/builder-amdci5-3/julialang/julia-master/src/gf.c:2039
ijl_method_table_insert at /cache/build/builder-amdci5-3/julialang/julia-master/src/gf.c:2233
ijl_method_def at /cache/build/builder-amdci5-3/julialang/julia-master/src/method.c:1305
eval_methoddef at /cache/build/builder-amdci5-3/julialang/julia-master/src/interpreter.c:112
eval_body at /cache/build/builder-amdci5-3/julialang/julia-master/src/interpreter.c:619
jl_interpret_toplevel_thunk at /cache/build/builder-amdci5-3/julialang/julia-master/src/interpreter.c:865
jl_toplevel_eval_flex at /cache/build/builder-amdci5-3/julialang/julia-master/src/toplevel.c:969
jl_eval_module_expr at /cache/build/builder-amdci5-3/julialang/julia-master/src/toplevel.c:215 [inlined]
jl_toplevel_eval_flex at /cache/build/builder-amdci5-3/julialang/julia-master/src/toplevel.c:762
jl_toplevel_eval_flex at /cache/build/builder-amdci5-3/julialang/julia-master/src/toplevel.c:909
jl_toplevel_eval_flex at /cache/build/builder-amdci5-3/julialang/julia-master/src/toplevel.c:909
ijl_toplevel_eval at /cache/build/builder-amdci5-3/julialang/julia-master/src/toplevel.c:980
ijl_toplevel_eval_in at /cache/build/builder-amdci5-3/julialang/julia-master/src/toplevel.c:1022
eval at ./boot.jl:432 [inlined]
include_string at ./loading.jl:2591
_include at ./loading.jl:2651
include at ./Base.jl:559 [inlined]
include_package_for_output at ./loading.jl:2769
jfptr_include_package_for_output_68716.1 at /home/nsajko/tmp/jl/jl/julia-6c17db1ba1/lib/julia/sys.so (unknown line)
jl_apply at /cache/build/builder-amdci5-3/julialang/julia-master/src/julia.h:2189 [inlined]
do_call at /cache/build/builder-amdci5-3/julialang/julia-master/src/interpreter.c:127
eval_value at /cache/build/builder-amdci5-3/julialang/julia-master/src/interpreter.c:224
eval_stmt_value at /cache/build/builder-amdci5-3/julialang/julia-master/src/interpreter.c:175 [inlined]
eval_body at /cache/build/builder-amdci5-3/julialang/julia-master/src/interpreter.c:660
jl_interpret_toplevel_thunk at /cache/build/builder-amdci5-3/julialang/julia-master/src/interpreter.c:865
jl_toplevel_eval_flex at /cache/build/builder-amdci5-3/julialang/julia-master/src/toplevel.c:969
jl_toplevel_eval_flex at /cache/build/builder-amdci5-3/julialang/julia-master/src/toplevel.c:909
ijl_toplevel_eval at /cache/build/builder-amdci5-3/julialang/julia-master/src/toplevel.c:980
ijl_toplevel_eval_in at /cache/build/builder-amdci5-3/julialang/julia-master/src/toplevel.c:1022
eval at ./boot.jl:432 [inlined]
include_string at ./loading.jl:2591
include_string at ./loading.jl:2601 [inlined]
exec_options at ./client.jl:323
_start at ./client.jl:533
jfptr__start_70211.1 at /home/nsajko/tmp/jl/jl/julia-6c17db1ba1/lib/julia/sys.so (unknown line)
jl_apply at /cache/build/builder-amdci5-3/julialang/julia-master/src/julia.h:2189 [inlined]
true_main at /cache/build/builder-amdci5-3/julialang/julia-master/src/jlapi.c:900
jl_repl_entrypoint at /cache/build/builder-amdci5-3/julialang/julia-master/src/jlapi.c:1059
main at /cache/build/builder-amdci5-3/julialang/julia-master/cli/loader_exe.c:58
unknown function (ip: 0x7573c61cac87)
__libc_start_main at /usr/lib/libc.so.6 (unknown line)
unknown function (ip: 0x4010b8)
unknown function (ip: (nil))
Allocations: 1 (Pool: 1; Big: 0); GC: 0

[nsajko]

Continuing from above, after second interrupt:

^C
[497804] signal 2: Interrupt
in expression starting at /home/nsajko/.julia/packages/LaurentPolynomials/Vje2Z/src/LaurentPolynomials.jl:901
jl_has_bound_typevars at /cache/build/builder-amdci5-3/julialang/julia-master/src/jltypes.c:271
ijl_has_typevar at /cache/build/builder-amdci5-3/julialang/julia-master/src/jltypes.c:276
finish_unionall at /cache/build/builder-amdci5-3/julialang/julia-master/src/subtype.c:3015
intersect_unionall_ at /cache/build/builder-amdci5-3/julialang/julia-master/src/subtype.c:3194
intersect_unionall at /cache/build/builder-amdci5-3/julialang/julia-master/src/subtype.c:3265
intersect at /cache/build/builder-amdci5-3/julialang/julia-master/src/subtype.c:3865
intersect_all at /cache/build/builder-amdci5-3/julialang/julia-master/src/subtype.c:4126
jl_type_intersection_env_s at /cache/build/builder-amdci5-3/julialang/julia-master/src/subtype.c:4348
jl_typemap_intersection_node_visitor at /cache/build/builder-amdci5-3/julialang/julia-master/src/typemap.c:543
jl_typemap_intersection_visitor at /cache/build/builder-amdci5-3/julialang/julia-master/src/typemap.c:812
jl_typemap_intersection_memory_visitor at /cache/build/builder-amdci5-3/julialang/julia-master/src/typemap.c:500
jl_typemap_intersection_visitor at /cache/build/builder-amdci5-3/julialang/julia-master/src/typemap.c:802
get_intersect_matches at /cache/build/builder-amdci5-3/julialang/julia-master/src/gf.c:1567 [inlined]
jl_method_table_activate at /cache/build/builder-amdci5-3/julialang/julia-master/src/gf.c:2039
ijl_method_table_insert at /cache/build/builder-amdci5-3/julialang/julia-master/src/gf.c:2233
ijl_method_def at /cache/build/builder-amdci5-3/julialang/julia-master/src/method.c:1305
eval_methoddef at /cache/build/builder-amdci5-3/julialang/julia-master/src/interpreter.c:112
eval_body at /cache/build/builder-amdci5-3/julialang/julia-master/src/interpreter.c:619
jl_interpret_toplevel_thunk at /cache/build/builder-amdci5-3/julialang/julia-master/src/interpreter.c:865
jl_toplevel_eval_flex at /cache/build/builder-amdci5-3/julialang/julia-master/src/toplevel.c:969
jl_eval_module_expr at /cache/build/builder-amdci5-3/julialang/julia-master/src/toplevel.c:215 [inlined]
jl_toplevel_eval_flex at /cache/build/builder-amdci5-3/julialang/julia-master/src/toplevel.c:762
jl_toplevel_eval_flex at /cache/build/builder-amdci5-3/julialang/julia-master/src/toplevel.c:909
jl_toplevel_eval_flex at /cache/build/builder-amdci5-3/julialang/julia-master/src/toplevel.c:909
ijl_toplevel_eval at /cache/build/builder-amdci5-3/julialang/julia-master/src/toplevel.c:980
ijl_toplevel_eval_in at /cache/build/builder-amdci5-3/julialang/julia-master/src/toplevel.c:1022
eval at ./boot.jl:432 [inlined]
include_string at ./loading.jl:2591
_include at ./loading.jl:2651
include at ./Base.jl:559 [inlined]
include_package_for_output at ./loading.jl:2769
jfptr_include_package_for_output_68716.1 at /home/nsajko/tmp/jl/jl/julia-6c17db1ba1/lib/julia/sys.so (unknown line)
jl_apply at /cache/build/builder-amdci5-3/julialang/julia-master/src/julia.h:2189 [inlined]
do_call at /cache/build/builder-amdci5-3/julialang/julia-master/src/interpreter.c:127
eval_value at /cache/build/builder-amdci5-3/julialang/julia-master/src/interpreter.c:224
eval_stmt_value at /cache/build/builder-amdci5-3/julialang/julia-master/src/interpreter.c:175 [inlined]
eval_body at /cache/build/builder-amdci5-3/julialang/julia-master/src/interpreter.c:660
jl_interpret_toplevel_thunk at /cache/build/builder-amdci5-3/julialang/julia-master/src/interpreter.c:865
jl_toplevel_eval_flex at /cache/build/builder-amdci5-3/julialang/julia-master/src/toplevel.c:969
jl_toplevel_eval_flex at /cache/build/builder-amdci5-3/julialang/julia-master/src/toplevel.c:909
ijl_toplevel_eval at /cache/build/builder-amdci5-3/julialang/julia-master/src/toplevel.c:980
ijl_toplevel_eval_in at /cache/build/builder-amdci5-3/julialang/julia-master/src/toplevel.c:1022
eval at ./boot.jl:432 [inlined]
include_string at ./loading.jl:2591
include_string at ./loading.jl:2601 [inlined]
exec_options at ./client.jl:323
_start at ./client.jl:533
jfptr__start_70211.1 at /home/nsajko/tmp/jl/jl/julia-6c17db1ba1/lib/julia/sys.so (unknown line)
jl_apply at /cache/build/builder-amdci5-3/julialang/julia-master/src/julia.h:2189 [inlined]
true_main at /cache/build/builder-amdci5-3/julialang/julia-master/src/jlapi.c:900
jl_repl_entrypoint at /cache/build/builder-amdci5-3/julialang/julia-master/src/jlapi.c:1059
main at /cache/build/builder-amdci5-3/julialang/julia-master/cli/loader_exe.c:58
unknown function (ip: 0x76ce340d6c87)
__libc_start_main at /usr/lib/libc.so.6 (unknown line)
unknown function (ip: 0x4010b8)
unknown function (ip: (nil))
Allocations: 1 (Pool: 1; Big: 0); GC: 0
ERROR: InterruptException:
Stacktrace:
  [1] try_yieldto(undo::typeof(Base.ensure_rescheduled))
    @ Base ./task.jl:1100
  [2] wait()
    @ Base ./task.jl:1164
  [3] wait(c::Base.GenericCondition{Base.Threads.SpinLock}; first::Bool)
    @ Base ./condition.jl:139
  [4] wait
    @ ./condition.jl:134 [inlined]
  [5] wait(x::Base.Process, syncd::Bool)
    @ Base ./process.jl:694
  [6] wait
    @ ./process.jl:687 [inlined]
  [7] success(x::Base.Process)
    @ Base ./process.jl:556
  [8] compilecache(pkg::Base.PkgId, path::String, internal_stderr::IO, internal_stdout::IO, keep_loaded_modules::Bool; flags::Cmd, cacheflags::Base.CacheFlags, reasons::Dict{String, Int64})
    @ Base ./loading.jl:2958
  [9] (::Base.var"#1102#1103"{Base.PkgId})()
    @ Base ./loading.jl:2437
 [10] mkpidlock(f::Base.var"#1102#1103"{Base.PkgId}, at::String, pid::Int32; kwopts::@Kwargs{stale_age::Int64, wait::Bool})
    @ FileWatching.Pidfile ~/tmp/jl/jl/julia-6c17db1ba1/share/julia/stdlib/v1.12/FileWatching/src/pidfile.jl:93
 [11] #mkpidlock#6
    @ ~/tmp/jl/jl/julia-6c17db1ba1/share/julia/stdlib/v1.12/FileWatching/src/pidfile.jl:88 [inlined]
 [12] trymkpidlock(::Function, ::Vararg{Any}; kwargs::@Kwargs{stale_age::Int64})
    @ FileWatching.Pidfile ~/tmp/jl/jl/julia-6c17db1ba1/share/julia/stdlib/v1.12/FileWatching/src/pidfile.jl:114
 [13] #invokelatest#2
    @ ./essentials.jl:1035 [inlined]
 [14] invokelatest
    @ ./essentials.jl:1030 [inlined]
 [15] maybe_cachefile_lock(f::Base.var"#1102#1103"{Base.PkgId}, pkg::Base.PkgId, srcpath::String; stale_age::Int64)
    @ Base ./loading.jl:3604
 [16] maybe_cachefile_lock
    @ ./loading.jl:3601 [inlined]
 [17] _require(pkg::Base.PkgId, env::String)
    @ Base ./loading.jl:2433
 [18] __require_prelocked(uuidkey::Base.PkgId, env::String)
    @ Base ./loading.jl:2266
 [19] #invoke_in_world#3
    @ ./essentials.jl:1067 [inlined]
 [20] invoke_in_world
    @ ./essentials.jl:1064 [inlined]
 [21] _require_prelocked(uuidkey::Base.PkgId, env::String)
    @ Base ./loading.jl:2257
 [22] macro expansion
    @ ./loading.jl:2197 [inlined]
 [23] macro expansion
    @ ./lock.jl:273 [inlined]
 [24] __require(into::Module, mod::Symbol)
    @ Base ./loading.jl:2154
 [25] #invoke_in_world#3
    @ ./essentials.jl:1067 [inlined]
 [26] invoke_in_world
    @ ./essentials.jl:1064 [inlined]
 [27] require(into::Module, mod::Symbol)
    @ Base ./loading.jl:2147

[nsajko]

Bisected to #53675, @N5N3. Indeed, this was caught back then by Nanosoldier's PkgEval of the PR, but wasn't noticed.

[N5N3]

Em that loop might be infinite if innervals have circular bounds.
I haven't checked it locally, but this specific intersection has been broken since v1.10

julia> S = Tuple{Val{S1} where {S1<:T1}, Union{Int,T1}} where {T1}
Tuple{Val{S1} where S1<:T1, Union{Int64, T1}} where T1

julia> T = Tuple{Union{Int,T2}, Val{S2} where {S2<:T2}} where {T2}
Tuple{Union{Int64, T2}, Val{S2} where S2<:T2} where T2

julia> typeintersect(S, T) |> Base.has_free_typevars
true

julia> versioninfo()
Julia Version 1.10.3
Commit 0b4590a550 (2024-04-30 10:59 UTC)
Build Info:
  Official https://julialang.org/ release
Platform Info:
  OS: Windows (x86_64-w64-mingw32)
  CPU: 16 × 12th Gen Intel(R) Core(TM) i7-12650H
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-15.0.7 (ORCJIT, alderlake)
Threads: 1 default, 0 interactive, 1 GC (on 16 virtual cores)

[N5N3]

Add the milestone as #53675 has been backported.