Spurious warnings when reading shapefiles

[dopplershift]

With GDAL >=3.7.3, I'm seeing the following when loading any of the US Census Bureau county borders files, for instance the 1:20m file:

Warning 1: us_counties_20m.shp contains polygon(s) with rings with invalid winding order. Autocorrecting them, but that shapefile should be corrected using ogr2ogr for example.

This warning came in with #8483, but for all I can tell, there's nothing wrong with the geometry in that file (ids 1524 and 1973 in the 1:20m file at least). Looking at the relevant code:

gdal/ogr/ogrsf_frmts/shape/shape2ogr.cpp

Lines 352 to 418 in 6133cf3

	for (int iRing = 1; iRing < psShape->nParts; iRing++)
	{
	tabPolygons[iRing]->getEnvelope(&sCurEnvelope);
	if (!sFirstEnvelope.Intersects(sCurEnvelope))
	{
	// If the envelopes of the rings don't intersect,
	// then it is clearly a multi-part polygon
	bUseSlowMethod = true;
	break;
	}
	else
	{
	// Otherwise take 4 points at each extremity of
	// the inner rings and check if there are in the
	// outer ring. If none are within it, then it is
	// very likely a outer ring (or an invalid ring
	// which is neither a outer nor a inner ring)
	auto poRing = tabPolygons[iRing]->getExteriorRing();
	const auto nNumPoints = poRing->getNumPoints();
	OGRPoint p;
	OGRPoint leftPoint(
	std::numeric_limits<double>::infinity(), 0);
	OGRPoint rightPoint(
	-std::numeric_limits<double>::infinity(), 0);
	OGRPoint bottomPoint(
	0, std::numeric_limits<double>::infinity());
	OGRPoint topPoint(
	0, -std::numeric_limits<double>::infinity());
	for (int iPoint = 0; iPoint < nNumPoints - 1;
	++iPoint)
	{
	poRing->getPoint(iPoint, &p);
	if (p.getX() < leftPoint.getX() ||
	(p.getX() == leftPoint.getX() &&
	p.getY() < leftPoint.getY()))
	{
	leftPoint = p;
	}
	if (p.getX() > rightPoint.getX() ||
	(p.getX() == rightPoint.getX() &&
	p.getY() > rightPoint.getY()))
	{
	rightPoint = p;
	}
	if (p.getY() < bottomPoint.getY() ||
	(p.getY() == bottomPoint.getY() &&
	p.getX() > bottomPoint.getX()))
	{
	bottomPoint = p;
	}
	if (p.getY() > topPoint.getY() ||
	(p.getY() == topPoint.getY() &&
	p.getX() < topPoint.getX()))
	{
	topPoint = p;
	}
	}
	if (!poRing->isPointInRing(&leftPoint) &&
	!poRing->isPointInRing(&rightPoint) &&
	!poRing->isPointInRing(&bottomPoint) &&
	!poRing->isPointInRing(&topPoint))
	{
	bUseSlowMethod = true;
	break;
	}
	}
	}

it says it's checking that points are in the "exterior ring", but near as I can tell the polygons in tabPolygons are all individual rings, so the exterior ring of any of those is polygons is itself. Is perhaps the correct line instead:

auto poRing = tabPolygons[0]->getExteriorRing();

? Otherwise, am I missing something here as to why the warning is actually correct?