CoordinateSequence: Fix logic error when adding XYM seq to XYZ seq (#999

)

Logic error only causes an incorrect result when GEOS_COORDSEQ_PADZ is
not defined.

Fixes #997

src/geom/CoordinateSequence.cpp

@@ -151,7 +151,7 @@ CoordinateSequence::initialize()
 void
 CoordinateSequence::add(const CoordinateSequence& cs, std::size_t from, std::size_t to)
 {
-    if (cs.stride() == stride() && cs.hasM() == cs.hasM()) {
+    if (cs.stride() == stride() && cs.hasM() == hasM()) {
         m_vect.insert(m_vect.end(),
                       std::next(cs.m_vect.cbegin(), static_cast<std::ptrdiff_t>(from * stride())),
                       std::next(cs.m_vect.cbegin(), static_cast<std::ptrdiff_t>((to + 1u)*stride())));

tests/unit/geom/CoordinateSequenceTest.cpp

@@ -1344,7 +1344,7 @@ void object::test<49>
     ensure_same(c1.z, 2);
 }
 
-// Test move contructor
+// Test move constructor
 template<>
 template<>
 void object::test<50>
@@ -1510,4 +1510,30 @@ void object::test<55>
     ensure_equals(seq1, expected);
 }
 
+// add XYM seq to XYZ seq
+template<>
+template<>
+void object::test<56>
+()
+{
+    CoordinateSequence seq1 = CoordinateSequence::XYZ(0);
+    CoordinateSequence seq2 = CoordinateSequence::XYM(0);
+
+    seq1.add(Coordinate(1, 2, 3));
+    seq1.add(Coordinate(4, 5, 6));
+
+    seq2.add(CoordinateXYM(7, 8, 9));
+    seq2.add(CoordinateXYM(10, 11, 12));
+
+    seq1.add(seq2);
+
+    ensure(seq1.hasZ());
+    ensure(!seq1.hasM());
+
+    ensure_equals_xyz(seq1.getAt(0), Coordinate{1, 2, 3});
+    ensure_equals_xyz(seq1.getAt(1), Coordinate{4, 5, 6});
+    ensure_equals_xyz(seq1.getAt(2), Coordinate{7, 8, DoubleNotANumber});
+    ensure_equals_xyz(seq1.getAt(3), Coordinate{10, 11, DoubleNotANumber});
+}
+
 } // namespace tut