[geos-devel] MSVC Unit Failure

[Mike Taves]

This issue is very tricky. Running the command from a local Windows build:
> test_geos_unit "geos::simplify::TopologyPreservingSimplifier"

will mostly fail (showing "tests summary: failures:1 ok:14"), but
occasionally pass (showing "tests summary: ok:15"), with a pass/fail
ratio close to 1:8. This type of random behaviour can only be
explained by a memory error, but is only an issue with Windows.
(Running the command on Linux with valgrind shows "All heap blocks
were freed -- no leaks are possible")

Looking at the AppVeyor history is slightly revealing:
https://ci.appveyor.com/project/dbaston/geos/history

The first captured instance of this issue was 4 months ago on the
overlay-sr branch:
https://ci.appveyor.com/project/dbaston/geos/builds/34227033/job/pq00xb0pirk5xpe9#L1032

It likely existed before this commit, up to (but not beyond) 6 months
ago, but was obscured by a different preceding error. Nevertheless, it
seems to have originated somewhere in the overlay-sr branch?