Make sure inset buffer is correctly set in math grid

Make MathData::setBuffer set the buffer of insets that it contains.
Remove corresponding code from InsetMathNest.

update the buffer() property in the following tabular-feature
actions : copy-row, add-row, copy-col, add-col.

(cherry picked from commit 837bcbb043)

src/mathed/InsetMathGrid.cpp

@@ -809,7 +809,7 @@ void InsetMathGrid::addRow(row_type row)
 {
 	rowinfo_.insert(rowinfo_.begin() + row + 1, RowInfo());
 	cells_.insert
-		(cells_.begin() + (row + 1) * ncols(), ncols(), MathData());
+		(cells_.begin() + (row + 1) * ncols(), ncols(), MathData(buffer_));
 	cellinfo_.insert
 		(cellinfo_.begin() + (row + 1) * ncols(), ncols(), CellInfo());
 }
@@ -833,8 +833,11 @@ void InsetMathGrid::delRow(row_type row)
 void InsetMathGrid::copyRow(row_type row)
 {
 	addRow(row);
-	for (col_type col = 0; col < ncols(); ++col)
+	for (col_type col = 0; col < ncols(); ++col) {
 		cells_[(row + 1) * ncols() + col] = cells_[row * ncols() + col];
+		// copying the cell does not set the buffer
+		cells_[(row + 1) * ncols() + col].setBuffer(*buffer_);
+	}
 }
 
 
@@ -864,6 +867,8 @@ void InsetMathGrid::addCol(col_type newcol)
 				= cellinfo_[row * nc + col];
 		}
 	swap(cells_, new_cells);
+	// copying cells loses the buffer reference
+	setBuffer(*buffer_);
 	swap(cellinfo_, new_cellinfo);
 
 	ColInfo inf;
@@ -895,8 +900,11 @@ void InsetMathGrid::delCol(col_type col)
 void InsetMathGrid::copyCol(col_type col)
 {
 	addCol(col+1);
-	for (row_type row = 0; row < nrows(); ++row)
+	for (row_type row = 0; row < nrows(); ++row) {
 		cells_[row * ncols() + col + 1] = cells_[row * ncols() + col];
+		// copying the cell does not set the buffer
+		cells_[row * ncols() + col + 1].setBuffer(*buffer_);
+	}
 }
 
 

src/mathed/InsetMathNest.cpp

@@ -118,11 +118,8 @@ InsetMathNest & InsetMathNest::operator=(InsetMathNest const & inset)
 void InsetMathNest::setBuffer(Buffer & buffer)
 {
 	InsetMath::setBuffer(buffer);
-	for (idx_type i = 0, n = nargs(); i != n; ++i) {
-		MathData & data = cell(i);
-		for (size_t j = 0; j != data.size(); ++j)
-			data[j].nucleus()->setBuffer(buffer);
-	}
+	for (MathData & data : cells_)
+		data.setBuffer(buffer);
 }
 
 

src/mathed/MathData.cpp

@@ -52,6 +52,14 @@ MathData::MathData(Buffer * buf, const_iterator from, const_iterator to)
 {}
 
 
+void MathData::setBuffer(Buffer & b)
+{
+	buffer_ = &b;
+	for (MathAtom & at : *this)
+		at.nucleus()->setBuffer(b);
+}
+
+
 MathAtom & MathData::operator[](pos_type pos)
 {
 	LBUFERR(pos < size());

src/mathed/MathData.h

@@ -185,7 +185,7 @@ public:
 	///
 	void updateBuffer(ParIterator const &, UpdateType);
 	///
-	void setBuffer(Buffer & b) { buffer_ = &b; }
+	void setBuffer(Buffer & b);
 
 protected:
 	/// cached values for super/subscript placement