Fallback to function when property's declaringType is unknown (#1416)

Author: jakebailey

src/Analysis/Ast/Impl/Analyzer/Symbols/SymbolCollector.cs

@@ -150,6 +150,12 @@ private PythonFunctionOverload GetOverloadFromStub(FunctionDefinition node) {
         }
 
         private bool TryAddProperty(FunctionDefinition node, IPythonType declaringType) {
+            // We can't add a property to an unknown type. Fallback to a regular function for now.
+            // TOOD: Decouple declaring types from the property.
+            if (declaringType.IsUnknown()) {
+                return false;
+            }
+
             var dec = node.Decorators?.Decorators;
             var decorators = dec != null ? dec.ExcludeDefault().ToArray() : Array.Empty<Expression>();
 

src/Analysis/Ast/Impl/Types/PythonFunctionType.cs

@@ -143,7 +143,9 @@ private void ProcessDecorators(FunctionDefinition fd) {
                         break;
                     case @"property":
                     case @"abstractproperty":
-                        Debug.Assert(false, "Found property attribute while processing function. Properties should be handled in the respective class.");
+                        // Ignore property decorators if the declaring type is unknown.
+                        // TODO: Restore this to a hard failure once property can handle not having a declaring type.
+                        Debug.Assert(DeclaringType.IsUnknown(), "Found property attribute while processing function. Properties should be handled in the respective class.");
                         break;
                 }
             }

src/Analysis/Ast/Test/ClassesTests.cs

@@ -634,5 +634,21 @@ def __init__(self):
             // Test run time: typically ~ 20 sec.
             sw.ElapsedMilliseconds.Should().BeLessThan(60000); 
         }
+
+        [TestMethod, Priority(0)]
+        public async Task NestedProperty() {
+            const string code = @"
+class x(object):
+    def func(self):
+        @property
+        def foo(*args, **kwargs):
+            pass
+        return 42
+
+a = x().func()
+";
+            var analysis = await GetAnalysisAsync(code);
+            analysis.Should().HaveVariable("a").OfType(BuiltinTypeId.Int);
+        }
     }
 }