C++: Expose block assignment operations in the QL library

Author: jketema

cpp/ql/lib/semmle/code/cpp/exprs/Assignment.qll

@@ -47,6 +47,20 @@ class AssignExpr extends Assignment, @assignexpr {
   override string toString() { result = "... = ..." }
 }
 
+/**
+ * A compiler generated assignment operation that may occur in a compiler generated
+ * copy/move constructor or assignment operator, and which functions like `memcpy`
+ * where the size argument is based on the type of the rvalue of the assignment.
+ */
+class BlockAssignExpr extends Assignment, @blockassignexpr {
+  override string getOperator() { result = "=" }
+
+  override string getAPrimaryQlClass() { result = "BlockAssignExpr" }
+
+  /** Gets a textual representation of this assignment. */
+  override string toString() { result = "... = ..." }
+}
+
 /**
  * A non-overloaded binary assignment operation other than `=`.
  *

cpp/ql/test/library-tests/ir/ir/PrintAST.expected

@@ -13985,7 +13985,7 @@ ir.cpp:
 #-----|         Type = [RValueReferenceType] A &&
 #-----|   getEntryPoint(): [BlockStmt] { ... }
 #-----|     getStmt(0): [ExprStmt] ExprStmt
-#-----|       getExpr(): (no string representation)
+#-----|       getExpr(): [BlockAssignExpr] ... = ...
 #-----|           Type = [VoidType] void
 #-----|           ValueCategory = prvalue
 #-----|         getLValue(): [PointerFieldAccess] e