Docs: add section on resolving the aliasing issue.
diff --git a/doc/snippets/TopicAliasing_block.cpp b/doc/snippets/TopicAliasing_block.cpp
index 7d40cfa..03282f4 100644
--- a/doc/snippets/TopicAliasing_block.cpp
+++ b/doc/snippets/TopicAliasing_block.cpp
@@ -1,5 +1,7 @@
MatrixXi mat(3,3);
mat << 1, 2, 3, 4, 5, 6, 7, 8, 9;
cout << "Here is the matrix mat:\n" << mat << endl;
+
+// This assignment shows the aliasing problem
mat.bottomRightCorner(2,2) = mat.topLeftCorner(2,2);
cout << "After the assignment, mat = \n" << mat << endl;
diff --git a/doc/snippets/TopicAliasing_block_correct.cpp b/doc/snippets/TopicAliasing_block_correct.cpp
new file mode 100644
index 0000000..6fee580
--- /dev/null
+++ b/doc/snippets/TopicAliasing_block_correct.cpp
@@ -0,0 +1,7 @@
+MatrixXi mat(3,3);
+mat << 1, 2, 3, 4, 5, 6, 7, 8, 9;
+cout << "Here is the matrix mat:\n" << mat << endl;
+
+// The eval() solves the aliasing problem
+mat.bottomRightCorner(2,2) = mat.topLeftCorner(2,2).eval();
+cout << "After the assignment, mat = \n" << mat << endl;