SONARPY-2424 Document limitation on AliasDescriptor to PythonType conversion (#2226)

Author: guillaume-dequenne

python-frontend/src/main/java/org/sonar/python/semantic/v2/converter/AliasDescriptorToPythonTypeConverter.java

@@ -23,7 +23,7 @@
 public class AliasDescriptorToPythonTypeConverter implements DescriptorToPythonTypeConverter {
   @Override
   public PythonType convert(ConversionContext ctx, Descriptor from) {
-    // We should try to retrieve the original type if possible, instead of recreating it
+    // SONARPY-2423: We should try to retrieve the original type if possible, instead of recreating it
     return ctx.convert(((AliasDescriptor) from).originalDescriptor());
   }
 }

python-frontend/src/test/java/org/sonar/python/types/v2/TypeCheckerTest.java

@@ -300,6 +300,33 @@ class B: pass
     assertThat(localTypeChecker.typeCheckBuilder().isTypeOrInstanceWithName("my_package.unknown.A").check(aType)).isEqualTo(TriBool.UNKNOWN);
   }
 
+  @Test
+  void typesFromAliasDescriptor() {
+    ProjectLevelSymbolTable projectLevelSymbolTable = ProjectLevelSymbolTable.empty();
+    ProjectLevelTypeTable projectLevelTypeTable = new ProjectLevelTypeTable(projectLevelSymbolTable);
+    PythonFile pythonFile = PythonTestUtils.pythonFile("mod.py");
+    TypeChecker localTypeChecker = new TypeChecker(projectLevelTypeTable);
+    var fileInput = parseAndInferTypes(projectLevelTypeTable, pythonFile, """
+      from fastapi.responses import Response as A
+      from starlette.responses import Response as B
+      A
+      B
+      """
+    );
+    var aType = ((ExpressionStatement) fileInput.statements().statements().get(2)).expressions().get(0).typeV2();
+    var bType = ((ExpressionStatement) fileInput.statements().statements().get(3)).expressions().get(0).typeV2();
+
+    // SONARPY-2423, the types for A and B should be identical, since fastapi.responses.Response is an alias to starlette.responses.Response
+    assertThat(localTypeChecker.typeCheckBuilder().isTypeOrInstanceWithName("fastapi.responses.Response").check(aType)).isEqualTo(TriBool.TRUE);
+    assertThat(localTypeChecker.typeCheckBuilder().isTypeOrInstanceWithName("fastapi.responses.Response").check(bType)).isEqualTo(TriBool.FALSE);
+
+    assertThat(localTypeChecker.typeCheckBuilder().isTypeOrInstanceWithName("starlette.responses.Response").check(aType)).isEqualTo(TriBool.FALSE);
+    assertThat(localTypeChecker.typeCheckBuilder().isTypeOrInstanceWithName("starlette.responses.Response").check(bType)).isEqualTo(TriBool.TRUE);
+
+    assertThat(aType).isNotEqualTo(bType);
+  }
+
+
 
   @Test
   void testIsInstance() {