Macaulay2 / Macaulay2/M2

Segfault in GBRing::gbvector_remove

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Dominant language
Macaulay2
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435
Forks
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Avg merge
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Merged PRs (30d)
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Description

I got the following segfault in an [Ubuntu 18.04 PPA build for amd64](https://launchpadlibrarian.net/650800080/buildlog_ubuntu-bionic-amd64.macaulay2_1.20.0.1+git202302100922-0ppa202302030935~ubuntu18.04.1_BUILDING.txt.gz). Is this some of the code that was just updated in #2769?

```m2
-- capturing check(12, "SubalgebraBases") -- SIGSEGV
-* stack trace, pid: 156733
0# stack_trace(std::ostream&, bool) at ./M2/Macaulay2/d/main.cpp:127
1# segv_handler at ./M2/Macaulay2/d/main.cpp:244
2# 0x00007F144EC83F10 in /lib/x86_64-linux-gnu/libc.so.6
3# GBRing::gbvector_remove(gbvector*) at ./M2/Macaulay2/e/gbring.cpp:289
4# ReducedGB::~ReducedGB() at ./M2/Macaulay2/e/reducedgb.cpp:47
5# 0x00007F14504FE74D in /usr/lib/x86_64-linux-gnu/libgc.so.1
6# 0x00007F14504FE9D4 in /usr/lib/x86_64-linux-gnu/libgc.so.1
```

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  3. Fork the repository and make your change on a branch.
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Research direction

Start by reproducing the `check(12, "SubalgebraBases")` failure from the Ubuntu 18.04 build, then read `M2/Macaulay2/e/gbring.cpp` around `GBRing::gbvector_remove` and `M2/Macaulay2/e/reducedgb.cpp` around `ReducedGB::~ReducedGB()`. Compare the relevant code with the update mentioned in issue #2769 and confirm that the check completes without a segmentation fault.

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Assessment

Tech stack
cpp
Domain
backend
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
35/100

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