[BE] Consider complex as impure for removeSimpleEquations

Belonging to [master]:
  - OpenModelica/OMCompiler#2982
  - OpenModelica/OpenModelica-testsuite#1141

Compiler/BackEnd/RemoveSimpleEquations.mo

@@ -1943,13 +1943,10 @@ algorithm
 
     case (_, _, _, _, _, (vars, shared as BackendDAE.SHARED(functionTree=functions), eqns, seqns, index, mT, _))
       guard
-        not Expression.isImpure(exp) // lochel: this is at least needed for impure functions
+        not Expression.isImpure(exp) and not Expression.containsComplexCall(exp) // lochel: this is at least needed for impure functions
       equation
         //exp2 = Ceval.cevalSimpleWithFunctionTreeReturnExp(exp, functions);
         exp2 = EvaluateFunctions.evaluateConstantFunctionCallExp(exp, functions, false);
-        if not Expression.isConst(exp2) then
-          exp2 = exp;
-        end if;
         if Flags.isSet(Flags.DEBUG_ALIAS) then
           BackendDump.debugStrCrefStrExpStr("Const Equation (through Ceval, case 1) ", cr, " = ", exp, " found.\n");
         end if;
@@ -1961,7 +1958,7 @@ algorithm
       // TODO: Remove or fix this case. We do not want to add function calls here as they are inlined in a very bad way sometimes.
     case (_, _, _, _, _, (vars, shared, eqns, seqns, index, mT, _))
       guard
-        not Expression.isImpure(exp) // lochel: this is at least needed for impure functions
+        not Expression.isImpure(exp) and not Expression.containsComplexCall(exp) // lochel: this is at least needed for impure functions
       equation
         if Flags.isSet(Flags.DEBUG_ALIAS) then
           BackendDump.debugStrCrefStrExpStr("Const Equation (through Ceval, case 2) ", cr, " = ", exp, " found.\n");

Compiler/FrontEnd/Expression.mo

@@ -7857,6 +7857,51 @@ algorithm
   end match;
 end isImpureWork;
 
+public function containsComplexCall "author: kabdelhak
+  Returns true if an expression contains a complex constructor call."
+  input DAE.Exp inExp;
+  output Boolean isCC;
+algorithm
+  (_, isCC) := traverseExpTopDown(inExp, containsComplexCallWork, false);
+end containsComplexCall;
+
+function containsComplexCallWork "author: kabdelhak"
+  input DAE.Exp inExp;
+  input Boolean inCC;
+  output DAE.Exp outExp;
+  output Boolean cont;
+  output Boolean outCC;
+algorithm
+  (outExp,cont,outCC) := match (inExp,inCC)
+    local
+      Absyn.Path path;
+      Boolean isCC;
+    case (_, true) then (inExp,true,true);
+    case (DAE.CALL(path = Absyn.FULLYQUALIFIED(path = path)), _)
+      equation
+        true = isComplexCall(path);
+      then (inExp,false,true);
+    else (inExp,true,false);
+  end match;
+end containsComplexCallWork;
+
+function isComplexCall "author: kabdelhak"
+  input Absyn.Path path;
+  output Boolean isCC;
+algorithm
+  isCC := match path
+    local
+      Absyn.Path innerPath;
+    case (Absyn.FULLYQUALIFIED(path = innerPath))
+      then isComplexCall(innerPath);
+    case (Absyn.QUALIFIED(name=".Complex"))
+      then true;
+    case (Absyn.IDENT(name=".Complex"))
+      then true;
+    else false;
+  end match;
+end isComplexCall;
+
 public function isConst
 "Returns true if an expression is constant"
   input DAE.Exp inExp;