segfault : data labels

Recipe 1: Read in the attached file data-labels-crash-del.gnumeric. Select the A1 cell and hit the <Delete> key. Observe immediate segmentation fault.

Recipe 2: Read in the slightly less boiled-down file data-labels-crash-pos.gnumeric. Observe many hundreds of messages such as the following:

 ** (gnumeric:13805): CRITICAL **: 17:29:33.592: go_data_vector_get_str: assertion '(int)i < vec-len' failed

 ** (gnumeric:13805): CRITICAL **: 17:29:33.593: go_data_vector_get_markup: assertion '(int)i < vec-len' failed

Select the A1 cell, then either

• hit the <Delete> key, or
• enter a smallish non-negative number.

Observe hundreds of additional CRITICAL messages, followed by an immediate segmentation fault.

Discussion: I don't know whether this is two manifestations of the same bug, or two completely different bugs. The presentation is similar but not identical. In particular, recipe 1 requires (not a plain number) and does not scribble error messages on the terminal.

This is not a newly-introduced bug. It has been bugging me for a long time. It's only now that I took the time to create a stripped-down test/demonstration case. Its is observed with the lastest git version of gnumeric, and with a variety of previous versions.

:; /usr/src/gnome/install/bin/gnumeric --version
gnumeric version '1.12.47'
datadir := '/usr/src/gnome/install/share/gnumeric/1.12.47'
libdir := '/usr/src/gnome/install/lib/gnumeric/1.12.47'

:; uname -srmo
Linux 4.19.42+ x86_64 GNU/Linux

:; lsb_release -a
LSB Version:    core-9.20170808ubuntu1-noarch:cxx-3.0-amd64:cxx-3.0-noarch:cxx-3.1-amd64:cxx-3.1-noarch:cxx-3.2-amd64:cxx-3.2-noarch:cxx-4.0-amd64:cxx-4.0-noarch:cxx-4.1-amd64:cxx-4.1-noarch:desktop-3.1-amd64:desktop-3.1-noarch:desktop-3.2-amd64:desktop-3.2-noarch:desktop-4.0-amd64:desktop-4.0-noarch:desktop-4.1-amd64:desktop-4.1-noarch:graphics-2.0-amd64:graphics-2.0-noarch:graphics-3.0-amd64:graphics-3.0-noarch:graphics-3.1-amd64:graphics-3.1-noarch:graphics-3.2-amd64:graphics-3.2-noarch:graphics-4.0-amd64:graphics-4.0-noarch:graphics-4.1-amd64:graphics-4.1-noarch:multimedia-3.2-amd64:multimedia-3.2-noarch:multimedia-4.0-amd64:multimedia-4.0-noarch:multimedia-4.1-amd64:multimedia-4.1-noarch:printing-9.20170808ubuntu1-noarch:qt4-3.1-amd64:qt4-3.1-noarch:security-9.20170808ubuntu1-noarch
Distributor ID: Ubuntu
Description:    Ubuntu 18.04.3 LTS
Release:        18.04
Codename:       bionic