fix: use valid add-to-list expression fixture

Symptom: PR #362 passed parser and unit tests but failed the integration mx check on add_expression_to_list.mdl with CE0117 at the generated ChangeListAction.

Root cause: the CI doctype fixture used head($SourceItems) directly as a ChangeListAction.Value. Studio Pro 11.9 rejects that expression in this slot even though the MDL parser accepts list-operation syntax as a generic expression. The branch-scope validator test also switched to an if expression and exposed that exprVarRefs did not recurse through IfThenElseExpr or SourceExpr.

Fix: change the doctype fixture and proposal example to an object-valued conditional expression that validates in Studio Pro, and teach exprVarRefs to recurse through IfThenElseExpr and SourceExpr so add-to-list expression references are still checked.

Tests: verified mxcli check for the fixture, the targeted integration subtest TestMxCheck_DoctypeScripts/add_expression_to_list.mdl, focused add-to-list validator tests, make build, make test, and make lint-go.

Author: hjothamendix

docs/11-proposals/PROPOSAL_microflow_add_expression_to_list.md

@@ -7,7 +7,7 @@ Status: Draft
 Allow `add` microflow statements to use any expression as the value being added to a list:
 
 ```mdl
-add head($SourceList) to $TargetList;
+add if $UseFirst then $FirstItem else $SecondItem to $TargetList;
 ```
 
 The existing variable-only form remains valid:
@@ -26,7 +26,7 @@ The parser stores the add value as an expression. For compatibility, a bare vari
 
 ## Tests And Examples
 
-`mdl-examples/doctype-tests/add_expression_to_list.test.mdl` demonstrates adding `head($SourceList)` to another list. Go regression tests cover parser behavior and builder output for both expression and simple-variable forms.
+`mdl-examples/doctype-tests/add_expression_to_list.mdl` demonstrates adding an object-valued conditional expression to another list. Go regression tests cover parser behavior and builder output for both expression and simple-variable forms.
 
 ## Open Questions
 

mdl-examples/doctype-tests/add_expression_to_list.mdl

@@ -5,13 +5,15 @@ create persistent entity AddListExample.Item (
 );
 /
 
-create microflow AddListExample.AddFirstItem (
-  $SourceItems: list of AddListExample.Item
+create microflow AddListExample.AddChosenItem (
+  $UseFirst: Boolean
 )
 returns list of AddListExample.Item as $Items
 begin
+  $First = create AddListExample.Item (Name = 'first');
+  $Second = create AddListExample.Item (Name = 'second');
   $Items = create list of AddListExample.Item;
-  add head($SourceItems) to $Items;
+  add if $UseFirst then $First else $Second to $Items;
   return $Items;
 end;
 /

mdl/executor/validate_microflow.go

@@ -537,6 +537,12 @@ func exprVarRefs(expr ast.Expression) []string {
 		}
 	case *ast.ParenExpr:
 		refs = append(refs, exprVarRefs(e.Inner)...)
+	case *ast.IfThenElseExpr:
+		refs = append(refs, exprVarRefs(e.Condition)...)
+		refs = append(refs, exprVarRefs(e.ThenExpr)...)
+		refs = append(refs, exprVarRefs(e.ElseExpr)...)
+	case *ast.SourceExpr:
+		refs = append(refs, exprVarRefs(e.Expression)...)
 	}
 	return refs
 }

mdl/executor/validate_microflow_add_to_list_test.go

@@ -15,10 +15,11 @@ func TestValidateMicroflowReferencesAddExpressionValue(t *testing.T) {
 returns Boolean
 begin
   declare $Items List of Synthetic.Item = empty;
+  declare $Fallback Synthetic.Item = empty;
   if true then
-    declare $SourceItems List of Synthetic.Item = empty;
+    declare $SourceItem Synthetic.Item = empty;
   end if;
-  add head($SourceItems) to $Items;
+  add if true then $SourceItem else $Fallback to $Items;
   return true;
 end;`
 
@@ -30,7 +31,7 @@ end;`
 
 	violations := ValidateMicroflow(stmt)
 	for _, violation := range violations {
-		if violation.RuleID == "MDL005" && strings.Contains(violation.Message, "$SourceItems") {
+		if violation.RuleID == "MDL005" && strings.Contains(violation.Message, "$SourceItem") {
 			return
 		}
 	}