Crash 'basis factorization does not exist'

[schillic]

We get an error with a simple unbounded problem.

min -x
s.t.
 x + y <=  1
-x - y <= -1

Below is the code. (Not sure if this helps: The original problem triggered the same error as in #116 but in the extracted example the error changed.)

pkg> st
      Status `~/Project.toml`
  [60bf3e95] GLPK v0.15.2
  [b8f27783] MathOptInterface v0.10.7

using GLPK
using MathOptInterface
const MOI = MathOptInterface
optimizer = GLPK.Optimizer(method=GLPK.EXACT)
c = [-1.0, 0]
A = [1.0 1; -1 -1]
b = [1.0, -1]
x = MOI.add_variables(optimizer, 2)

MOI.set(optimizer,
        MOI.ObjectiveFunction{MOI.ScalarAffineFunction{Float64}}(),
        MOI.ScalarAffineFunction(MOI.ScalarAffineTerm.(c, x), 0.0)
       )
MOI.set(optimizer, MOI.ObjectiveSense(), MOI.MIN_SENSE)
for i in 1:2
    MOI.add_constraint(optimizer,
                       MOI.ScalarAffineFunction(MOI.ScalarAffineTerm.(A[i, :], x), 0.0),
                       MOI.LessThan(b[i])
                      )
end
MOI.optimize!(optimizer)

glp_eval_tab_col: basis factorization does not exist
Error detected in file draft/glpapi12.c at line 923

signal (6): Aborted
in expression starting at REPL[12]:1
gsignal at /lib/x86_64-linux-gnu/libc.so.6 (unknown line)
abort at /lib/x86_64-linux-gnu/libc.so.6 (unknown line)
errfunc at /workspace/srcdir/glpk-5.0/src/env/error.c:53
glp_eval_tab_col at /workspace/srcdir/glpk-5.0/src/draft/glpapi12.c:923
glp_eval_tab_col at ~/.julia/packages/GLPK/mQmKc/src/gen/libglpk_api.jl:446 [inlined]
_get_unbounded_ray at ~/.julia/packages/GLPK/mQmKc/src/MOI_wrapper/infeasibility_certificates.jl:102
optimize! at ~/.julia/packages/GLPK/mQmKc/src/MOI_wrapper/MOI_wrapper.jl:1451
_jl_invoke at /buildworker/worker/package_linux64/build/src/gf.c:2247 [inlined]
jl_apply_generic at /buildworker/worker/package_linux64/build/src/gf.c:2429
jl_apply at /buildworker/worker/package_linux64/build/src/julia.h:1788 [inlined]
do_call at /buildworker/worker/package_linux64/build/src/interpreter.c:126
eval_value at /buildworker/worker/package_linux64/build/src/interpreter.c:215
eval_stmt_value at /buildworker/worker/package_linux64/build/src/interpreter.c:166 [inlined]
eval_body at /buildworker/worker/package_linux64/build/src/interpreter.c:587
jl_interpret_toplevel_thunk at /buildworker/worker/package_linux64/build/src/interpreter.c:731
jl_toplevel_eval_flex at /buildworker/worker/package_linux64/build/src/toplevel.c:885
jl_toplevel_eval_flex at /buildworker/worker/package_linux64/build/src/toplevel.c:830
jl_toplevel_eval_flex at /buildworker/worker/package_linux64/build/src/toplevel.c:830
jl_toplevel_eval_in at /buildworker/worker/package_linux64/build/src/toplevel.c:944
eval at ./boot.jl:373 [inlined]
eval_user_input at /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.7/REPL/src/REPL.jl:150
repl_backend_loop at /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.7/REPL/src/REPL.jl:244
start_repl_backend at /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.7/REPL/src/REPL.jl:229
#run_repl#47 at /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.7/REPL/src/REPL.jl:362
run_repl at /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.7/REPL/src/REPL.jl:349
_jl_invoke at /buildworker/worker/package_linux64/build/src/gf.c:2247 [inlined]
jl_apply_generic at /buildworker/worker/package_linux64/build/src/gf.c:2429
#930 at ./client.jl:394
jfptr_YY.930_32578.clone_1 at ~/programs/julia-1.7.0/lib/julia/sys.so (unknown line)
_jl_invoke at /buildworker/worker/package_linux64/build/src/gf.c:2247 [inlined]
jl_apply_generic at /buildworker/worker/package_linux64/build/src/gf.c:2429
jl_apply at /buildworker/worker/package_linux64/build/src/julia.h:1788 [inlined]
jl_f__call_latest at /buildworker/worker/package_linux64/build/src/builtins.c:757
#invokelatest#2 at ./essentials.jl:716 [inlined]
invokelatest at ./essentials.jl:714 [inlined]
run_main_repl at ./client.jl:379
exec_options at ./client.jl:309
_start at ./client.jl:495
jfptr__start_43127.clone_1 at ~/programs/julia-1.7.0/lib/julia/sys.so (unknown line)
_jl_invoke at /buildworker/worker/package_linux64/build/src/gf.c:2247 [inlined]
jl_apply_generic at /buildworker/worker/package_linux64/build/src/gf.c:2429
jl_apply at /buildworker/worker/package_linux64/build/src/julia.h:1788 [inlined]
true_main at /buildworker/worker/package_linux64/build/src/jlapi.c:559
jl_repl_entrypoint at /buildworker/worker/package_linux64/build/src/jlapi.c:701
main at /buildworker/worker/package_linux64/build/cli/loader_exe.c:42
__libc_start_main at /lib/x86_64-linux-gnu/libc.so.6 (unknown line)
_start at ~/programs/julia-1.7.0/bin/julia (unknown line)
Allocations: 7661027 (Pool: 7658281; Big: 2746); GC: 8
Aborted (core dumped)

[odow]

Thanks for the report. It looks like I need to re-introduce the error handling code: #206 (comment)

[schillic]

Thanks for the prompt fix!