one more Julia crash

[ThomasBreuer]

The following happens in Julia 1.12.0 and seems to be reproducible.
I start Julia, load Oscar, and then enter GAP.Globals.Pc, followed by <TAB>.
All involved Julia packages are the currently released versions,
in particular GAP.jl has version 0.15.4; GAP itself is version 4.14.0.

(The problem disappears if I enter using GAP instead of using Oscar.)

               _
   _       _ _(_)_     |  Documentation: https://docs.julialang.org
  (_)     | (_) (_)    |
   _ _   _| |_  __ _   |  Type "?" for help, "]?" for Pkg help.
  | | | | | | |/ _` |  |
  | | |_| | | | (_| |  |  Version 1.12.0 (2025-10-07)
 _/ |\__'_|_|_|\__'_|  |  Official https://julialang.org release
|__/                   |

julia> using Oscar
  ___   ___   ___    _    ____
 / _ \ / __\ / __\  / \  |  _ \  | Combining and extending ANTIC, GAP,
| |_| |\__ \| |__  / ^ \ |  ´ /  | Polymake and Singular
 \___/ \___/ \___//_/ \_\|_|\_\  | Type "?Oscar" for more information
o--------o-----o-----o--------o  | Documentation: https://docs.oscar-system.org
  S Y M B O L I C   T O O L S    | Version 1.5.0

julia> GAP.Globals.Pc
[20800] signal 11 (128): Segmentation fault
in expression starting at REPL[1]:1
OBJ_LVAR at /workspace/srcdir/gap-4.14.0/src/vars.h:240 [inlined]
OBJ_REF_LVAR at /workspace/srcdir/gap-4.14.0/src/exprs.h:33 [inlined]
EVAL_EXPR at /workspace/srcdir/gap-4.14.0/src/exprs.h:92 [inlined]
EvalOrExecCall at /workspace/srcdir/gap-4.14.0/src/funcs.c:113 [inlined]
ExecProccall0args at /workspace/srcdir/gap-4.14.0/src/funcs.c:212
EXEC_STAT at /workspace/srcdir/gap-4.14.0/src/stats.c:55 [inlined]
ExecSeqStatHelper at /workspace/srcdir/gap-4.14.0/src/stats.c:147 [inlined]
ExecSeqStat3 at /workspace/srcdir/gap-4.14.0/src/stats.c:170
EXEC_STAT at /workspace/srcdir/gap-4.14.0/src/stats.c:55 [inlined]
EXEC_CURR_FUNC at /workspace/srcdir/gap-4.14.0/src/stats.c:61
DoExecFunc at /workspace/srcdir/gap-4.14.0/src/funcs.c:467 [inlined]
DoExecFunc0args at /workspace/srcdir/gap-4.14.0/src/funcs.c:482
_call_gap_func at /home/sam/.julia/packages/GAP/UXSq3/src/ccalls.jl:346 [inlined]
GapObj at /home/sam/.julia/packages/GAP/UXSq3/src/ccalls.jl:329
unknown function (ip: 0x7f769d5ed71f) at (unknown file)
propertynames at /home/sam/.julia/packages/GAP/UXSq3/src/globals.jl:67
unknown function (ip: 0x7f769d64b3e8) at (unknown file)
#complete_symbol!#6 at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-12/usr/share/julia/stdlib/v1.12/REPL/src/REPLCompletions.jl:230
complete_symbol! at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-12/usr/share/julia/stdlib/v1.12/REPL/src/REPLCompletions.jl:184
unknown function (ip: 0x7f769d62afc6) at (unknown file)
completions at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-12/usr/share/julia/stdlib/v1.12/REPL/src/REPLCompletions.jl:1147
#complete_line#66 at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-12/usr/share/julia/stdlib/v1.12/REPL/src/REPL.jl:809
complete_line at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-12/usr/share/julia/stdlib/v1.12/REPL/src/REPL.jl:807
unknown function (ip: 0x7f769d62aedc) at (unknown file)
#complete_line_named#17 at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-12/usr/share/julia/stdlib/v1.12/REPL/src/LineEdit.jl:401
complete_line_named at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-12/usr/share/julia/stdlib/v1.12/REPL/src/LineEdit.jl:400 [inlined]
macro expansion at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-12/usr/share/julia/stdlib/v1.12/REPL/src/LineEdit.jl:442 [inlined]
macro expansion at ./lock.jl:376 [inlined]
#check_show_hint##2 at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-12/usr/share/julia/stdlib/v1.12/REPL/src/LineEdit.jl:439
jfptr_YY.check_show_hintYY.YY.2_17129.1 at /export/home/sam/julia/julia-1.12.0/share/julia/compiled/v1.12/REPL/u0gqU_g0Uq3.so (unknown line)
jl_apply at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-12/src/julia.h:2387 [inlined]
start_task at /cache/build/builder-amdci4-0/julialang/julia-release-1-dot-12/src/task.c:1249
Allocations: 29676167 (Pool: 29642473; Big: 33694); GC: 17
Segmentation fault (core dumped)

[fingolfin]

I can't reproduce this on my Mac and on a Linux machine, with Oscar 1.5.0 (freshly installed) in Julia 1.12.1 and 1.12.0

Could you try deleting your ~/.julia/compiled directory and trying again? Maybe something there got corrupted?

[ThomasBreuer]

I get the same crash with a fresh installation of Julia 1.12.1.

Also after removing ~/.julia/compiled, the problem is still present in Julia 1.12.0.

[ThomasBreuer]

Now I get this crash in Julia 1.12.1 sometimes also after entering using GAP instead of using Oscar, and then entering GAP.Globals.Pc, followed by more than one <TAB>.

[benlorenz]

I can confirm that this crash happens, it doesn't happen every time for me and it might need the REPL TAB-complete hints to be enabled to trigger.

With

atreplinit() do repl
    if VERSION >= v"1.11.0-0"
        repl.options.hint_tab_completes = false
    end
end

in my startup I am unable to reproduce it. Once I comment it I do see such a crash:

julia> GAP.Globals.Pc
[32158] signal 11 (1): Segmentation fault
in expression starting at REPL[1]:1
EXEC_STAT at /workspace/srcdir/gap-4.14.0/src/stats.c:53 [inlined]
ExecSeqStatHelper at /workspace/srcdir/gap-4.14.0/src/stats.c:147 [inlined]
ExecSeqStat3 at /workspace/srcdir/gap-4.14.0/src/stats.c:170
EXEC_STAT at /workspace/srcdir/gap-4.14.0/src/stats.c:55 [inlined]
EXEC_CURR_FUNC at /workspace/srcdir/gap-4.14.0/src/stats.c:61
DoExecFunc at /workspace/srcdir/gap-4.14.0/src/funcs.c:467 [inlined]
DoExecFunc0args at /workspace/srcdir/gap-4.14.0/src/funcs.c:482
_call_gap_func at /home/lorenz/.julia/packages/GAP/UXSq3/src/ccalls.jl:346 [inlined]
GapObj at /home/lorenz/.julia/packages/GAP/UXSq3/src/ccalls.jl:329
unknown function (ip: 0x7f887fd1de3f) at (unknown file)
propertynames at /home/lorenz/.julia/packages/GAP/UXSq3/src/globals.jl:67
unknown function (ip: 0x7f887fd870f8) at (unknown file)
#complete_symbol!#6 at /cache/build/tester-amdci4-14/julialang/julia-release-1-dot-12/usr/share/julia/stdlib/v1.12/REPL/src/REPLCompletions.jl:230
complete_symbol! at /cache/build/tester-amdci4-14/julialang/julia-release-1-dot-12/usr/share/julia/stdlib/v1.12/REPL/src/REPLCompletions.jl:184
unknown function (ip: 0x7f887fd62206) at (unknown file)
completions at /cache/build/tester-amdci4-14/julialang/julia-release-1-dot-12/usr/share/julia/stdlib/v1.12/REPL/src/REPLCompletions.jl:1150
#complete_line#66 at /cache/build/tester-amdci4-14/julialang/julia-release-1-dot-12/usr/share/julia/stdlib/v1.12/REPL/src/REPL.jl:809
complete_line at /cache/build/tester-amdci4-14/julialang/julia-release-1-dot-12/usr/share/julia/stdlib/v1.12/REPL/src/REPL.jl:807
unknown function (ip: 0x7f887fd615cc) at (unknown file)
#complete_line_named#17 at /cache/build/tester-amdci4-14/julialang/julia-release-1-dot-12/usr/share/julia/stdlib/v1.12/REPL/src/LineEdit.jl:401
complete_line_named at /cache/build/tester-amdci4-14/julialang/julia-release-1-dot-12/usr/share/julia/stdlib/v1.12/REPL/src/LineEdit.jl:400 [inlined]
macro expansion at /cache/build/tester-amdci4-14/julialang/julia-release-1-dot-12/usr/share/julia/stdlib/v1.12/REPL/src/LineEdit.jl:442 [inlined]
macro expansion at ./lock.jl:376 [inlined]
#check_show_hint##2 at /cache/build/tester-amdci4-14/julialang/julia-release-1-dot-12/usr/share/julia/stdlib/v1.12/REPL/src/LineEdit.jl:439
jfptr_YY.check_show_hintYY.YY.2_17954.1 at /home/lorenz/software/polymake/julia/julia/julia-1.12.1/share/julia/compiled/v1.12/REPL/u0gqU_UDl4g.so (unknown line)
jl_apply at /cache/build/tester-amdci4-14/julialang/julia-release-1-dot-12/src/julia.h:2391 [inlined]
start_task at /cache/build/tester-amdci4-14/julialang/julia-release-1-dot-12/src/task.c:1249
Allocations: 25072107 (Pool: 25038599; Big: 33508); GC: 15
Segmentation fault

(Linux, julia 1.12.1)

[ThomasBreuer]

With Julia 1.12.2, I cannot reproduce the crash anymore.

[lgoettgens]

I just managed to get the same crash with julia 1.12.2 and GAP.jl 0.16.1, but it's not really reproducible

[fingolfin]

Of course memory management is always a hot candidate for this kind of issue. Perhaps we can turn on printing that notifies us whenever a GC is done, and then see if this crash happens shortly after a GC took place