[NF] Expand complex array crefs.

- Expand crefs where one of the prefix nodes is an array, i.e.
  a.b.c => {a.b[1].c, a.b[2].c}, to work around backend issues.
- Fix order of equations in if-equations.

Belonging to [master]:
  - #2919
  - OpenModelica/OpenModelica-testsuite#1119

Author: perost

3rdParty

@@ -850,5 +850,29 @@ public
     end match;
   end depth;
 
+  function isComplexArray
+    input ComponentRef cref;
+    output Boolean complexArray;
+  algorithm
+    complexArray := match cref
+      case CREF() then isComplexArray2(cref.restCref);
+      else false;
+    end match;
+  end isComplexArray;
+
+  function isComplexArray2
+    input ComponentRef cref;
+    output Boolean complexArray;
+  algorithm
+    complexArray := match cref
+      case CREF(ty = Type.ARRAY())
+        guard Type.isArray(Type.subscript(cref.ty, cref.subscripts))
+        then true;
+
+      case CREF() then isComplexArray2(cref.restCref);
+      else false;
+    end match;
+  end isComplexArray2;
+
 annotation(__OpenModelica_Interface="frontend");
 end NFComponentRef;

Compiler/NFFrontEnd/NFComponentRef.mo

@@ -997,7 +997,7 @@ algorithm
         algorithm
           // Flatten the condition and body of the branch.
           cond := flattenExp(cond, prefix);
-          eql := flattenEquations(eql, prefix);
+          eql := listReverseInPlace(flattenEquations(eql, prefix));
 
           // Evaluate structural conditions.
           if var <= Variability.STRUCTURAL_PARAMETER then

Compiler/NFFrontEnd/NFFlatten.mo

@@ -70,7 +70,9 @@ algorithm
   end for;
 
   flatModel.variables := listReverseInPlace(vars);
+  flatModel.equations := Equation.mapExpList(flatModel.equations, expandComplexCref);
   flatModel.equations := scalarizeEquations(flatModel.equations);
+  flatModel.initialEquations := Equation.mapExpList(flatModel.initialEquations, expandComplexCref);
   flatModel.initialEquations := scalarizeEquations(flatModel.initialEquations);
   flatModel.algorithms := list(scalarizeAlgorithm(a) for a in flatModel.algorithms);
   flatModel.initialAlgorithms := list(scalarizeAlgorithm(a) for a in flatModel.initialAlgorithms);
@@ -111,7 +113,7 @@ algorithm
     (ty_attr_names, ty_attr_iters) := scalarizeTypeAttributes(ty_attr);
 
     if Binding.isBound(binding) then
-      binding_iter := ExpressionIterator.fromExp(Binding.getTypedExp(binding));
+      binding_iter := ExpressionIterator.fromExp(expandComplexCref(Binding.getTypedExp(binding)));
       bind_var := Binding.variability(binding);
 
       for cr in crefs loop
@@ -127,6 +129,7 @@ algorithm
       end for;
     end if;
   else
+    var.binding := Binding.mapExp(var.binding, expandComplexCref);
     vars := var :: vars;
   end if;
 end scalarizeVariable;
@@ -169,6 +172,32 @@ algorithm
   end for;
 end nextTypeAttributes;
 
+function expandComplexCref
+  input output Expression exp;
+algorithm
+  exp := Expression.map(exp, expandComplexCref_traverser);
+end expandComplexCref;
+
+function expandComplexCref_traverser
+  input output Expression exp;
+algorithm
+  () := match exp
+    case Expression.CREF(ty = Type.ARRAY())
+      algorithm
+        // Expand crefs where any of the prefix nodes are arrays. For example if
+        // b in a.b.c is SomeType[2] we expand it into {a.b[1].c, a.b[2].c}.
+        // TODO: This is only done due to backend issues and shouldn't be
+        //       necessary.
+        if ComponentRef.isComplexArray(exp.cref) then
+          exp := ExpandExp.expand(exp);
+        end if;
+      then
+        ();
+
+    else ();
+  end match;
+end expandComplexCref_traverser;
+
 function scalarizeEquations
   input list<Equation> eql;
   output list<Equation> equations = {};