Potential bug in CS::add()

[pramsey]

This line

geos/src/geom/CoordinateSequence.cpp

Line 154 in 4767afd

if (cs.stride() == stride() && cs.hasM() == cs.hasM()) {

Seems mighty suspicious, testing cs.hasM() == cs.hasM() ... @mwtoews or @dbaston can you look?

[dbaston]

Definitely incorrect although it would only cause an error with an unpadded XYM sequence which GEOS does not currently use:

geos/src/geom/CoordinateSequence.cpp

Lines 41 to 48 in 4767afd

	// If GEOS_COORDSEQ_PADZ is defined:
	// - XY sequences will be stored as XYZ
	// - XYM sequences will be stored as XYZM
	// This prevents incorrect results when an XYZ Coordinate is read from
	// a sequence storing XY or XYM. When GEOS is changed to check
	// coordinate types throughout the libary, this can be undefined to
	// store coordinates efficiently.
	#define GEOS_COORDSEQ_PADZ