Fix segfault with imports across multiple directories

src/debug.h

@@ -93,6 +93,7 @@ struct Debug
     bool mNewLine;
 };
 
+void listModelsUnits(const ModelPtr &model);
 void printAnalyserModelEquations(const AnalyserModelPtr &model);
 void printAnalyserModelVariables(const AnalyserModelPtr &model);
 void printAstAsTree(const AnalyserEquationAstPtr &ast);
@@ -101,16 +102,15 @@ void printComponentMap(const ComponentMap &map);
 void printConnectionMap(const ConnectionMap &map);
 void printEquivalenceMap(const EquivalenceMap &map);
 void printEquivalenceMapWithModelInfo(const EquivalenceMap &map, const ModelPtr &model);
+void printEquivalences(const VariablePtr &variable);
 void printHistory(const History &history);
 void printHistoryEpoch(const HistoryEpochPtr &historyEpoch);
 void printImportLibrary(const ImportLibrary &importlibrary);
+void printNamedPath(const ParentedEntityPtr &parented);
 void printStack(const IndexStack &stack);
 void printStackWithModelInfo(const IndexStack &stack, const ModelPtr &model);
 void printStringStringMap(const StringStringMap &map);
-void printVariableMap(const VariableMap &map);
 void printUnits(const UnitsPtr &units);
-void listModelsUnits(const ModelPtr &model);
-void printNamedPath(const ParentedEntityPtr &parented);
-void printEquivalences(const VariablePtr &variable);
+void printVariableMap(const VariableMap &map);
 
 } // namespace libcellml

src/importer.cpp

@@ -909,7 +909,7 @@ ComponentPtr flattenComponent(const ComponentEntityPtr &parent, ComponentPtr &co
                 }
             }
 
-            auto replacementUnits = (flattenedUnits != nullptr) ? flattenedUnits->clone() : units;
+            auto replacementUnits = (flattenedUnits != nullptr) ? flattenedUnits : units;
 
             for (size_t unitIndex = 0; unitIndex < replacementUnits->unitCount(); ++unitIndex) {
                 const std::string ref = replacementUnits->unitAttributeReference(unitIndex);

tests/importer/model_flattening.cpp

@@ -1918,3 +1918,28 @@ TEST(ModelFlattening, modelWithCnUnitsNotDefinedInImportedComponent)
     EXPECT_EQ(size_t(1), importer->errorCount());
     EXPECT_EQ("The model is not fully defined.", importer->error(0)->description());
 }
+
+TEST(ModelFlattening, multiLayeredImportOfNonStandardUnits)
+{
+    auto parser = libcellml::Parser::create(false);
+    auto model = parser->parseModel(fileContents("importer/periodicstimulus/experiments/periodic-stimulus.xml"));
+
+    EXPECT_EQ(size_t(0), parser->errorCount());
+
+    auto validator = libcellml::Validator::create();
+
+    validator->validateModel(model);
+
+    EXPECT_EQ(size_t(0), validator->issueCount());
+    EXPECT_TRUE(model->hasUnresolvedImports());
+
+    auto importer = libcellml::Importer::create(false);
+
+    importer->resolveImports(model, resourcePath("importer/periodicstimulus/experiments"));
+
+    EXPECT_FALSE(model->hasUnresolvedImports());
+
+    auto flattenModel = importer->flattenModel(model);
+
+    EXPECT_NE(nullptr, flattenModel);
+}

tests/resources/importer/periodicstimulus/components/INa.xml

@@ -0,0 +1,9 @@
+<?xml version='1.0' encoding='UTF-8'?>
+<model name="INa" xmlns="http://www.cellml.org/cellml/1.1#" xmlns:cellml="http://www.cellml.org/cellml/1.1#" xmlns:cmeta="http://www.cellml.org/metadata/1.0#" xmlns:xlink="http://www.w3.org/1999/xlink">
+    <import xlink:href="units.xml">
+        <units name="uA_per_cmsq" units_ref="uA_per_cmsq"/>
+    </import>
+    <component name="INa">
+        <variable name="INa" private_interface="out" public_interface="out" units="uA_per_cmsq"/>
+    </component>
+</model>

tests/resources/importer/periodicstimulus/components/stimulated.xml

@@ -0,0 +1,23 @@
+<?xml version='1.0' encoding='UTF-8'?>
+<model name="stimulated" xmlns="http://www.cellml.org/cellml/1.1#" xmlns:cellml="http://www.cellml.org/cellml/1.1#" xmlns:cmeta="http://www.cellml.org/metadata/1.0#" xmlns:xlink="http://www.w3.org/1999/xlink">
+    <import xlink:href="units.xml">
+        <units name="uA_per_cmsq" units_ref="uA_per_cmsq"/>
+    </import>
+    <import xlink:href="INa.xml">
+        <component component_ref="INa" name="INa"/>
+    </import>
+    <component name="action_potential">
+<!--        <variable name="Istim" private_interface="out" public_interface="in" units="uA_per_cmsq"/>-->
+        <variable name="INa" private_interface="in" public_interface="out" units="uA_per_cmsq"/>
+    </component>
+    <group>
+        <relationship_ref relationship="encapsulation"/>
+        <component_ref component="action_potential">
+            <component_ref component="INa"/>
+        </component_ref>
+    </group>
+    <connection>
+        <map_components component_1="action_potential" component_2="INa"/>
+        <map_variables variable_1="INa" variable_2="INa"/>
+    </connection>
+</model>

tests/resources/importer/periodicstimulus/components/units.xml

@@ -0,0 +1,13 @@
+<?xml version='1.0' encoding='UTF-8'?>
+<model name="units" xmlns="http://www.cellml.org/cellml/1.1#" xmlns:cellml="http://www.cellml.org/cellml/1.1#">
+    <units name="cm">
+        <unit prefix="centi" units="metre"/>
+    </units>
+    <units name="uA">
+        <unit prefix="micro" units="ampere"/>
+    </units>
+    <units name="uA_per_cmsq">
+        <unit units="uA"/>
+        <unit exponent="-2" units="cm"/>
+    </units>
+</model>

tests/resources/importer/periodicstimulus/experiments/periodic-stimulus.xml

@@ -0,0 +1,9 @@
+<?xml version='1.0' encoding='UTF-8'?>
+<model name="periodic_stimulus" xmlns="http://www.cellml.org/cellml/1.1#" xmlns:cellml="http://www.cellml.org/cellml/1.1#" xmlns:xlink="http://www.w3.org/1999/xlink">
+    <import xlink:href="../components/units.xml">
+        <units name="uA_per_cmsq" units_ref="uA_per_cmsq"/>
+    </import>
+    <import xlink:href="../components/stimulated.xml">
+        <component component_ref="action_potential" name="_model"/>
+    </import>
+</model>

tests/test_utils.cpp

@@ -91,7 +91,7 @@ static const std::string FIXED_INDENT = "    ";
 
 void printComponent(const libcellml::ComponentPtr &component, size_t c, const std::string &indent, bool includeMaths)
 {
-    if (c == -1) {
+    if (c == size_t(-1)) {
         std::cout << "COMPONENT: '" << component->name() << "'";
     } else {
         std::cout << indent << "[" << c + 1 << "]: " << component->name();