[Cpp] Use array assign in for loops

Belonging to [master]:
  - #2793
  - OpenModelica/OpenModelica-testsuite#1079

Author: rfranke

Compiler/Template/CodegenCpp.tpl

@@ -11570,7 +11570,10 @@ template equationForLoop(SimEqSystem eq, Context context, Text &varDecls, SimCod
       <<
       for (int <%iterExp%> = <%startExp%>; <%iterExp%> <= <%endExp%>; <%iterExp%>++) {
         <%preExp%>
-        <%crefPart%> = <%expPart%>;
+        <%if isArrayType(crefTypeFull(cref)) then
+          '<%crefPart%>.assign(<%expPart%>);'
+        else
+          '<%crefPart%> = <%expPart%>;'%>
       }
       >>
 end equationForLoop;

Compiler/Template/SimCodeTV.mo

@@ -3233,6 +3233,11 @@ package ComponentReference
     output list<DAE.Subscript> subs;
   end crefSubs;
 
+  function crefTypeFull
+    input DAE.ComponentRef inRef;
+    output DAE.Type res;
+  end crefTypeFull;
+
   function crefLastType
     input DAE.ComponentRef inRef;
     output DAE.Type res;