From 2abd802fe632fa350ab93d2c4cafdc5637c22115 Mon Sep 17 00:00:00 2001
From: Eric Traut <erictr@microsoft.com>
Date: Thu, 18 Apr 2019 07:45:50 -0700
Subject: [PATCH] Added new config feature: reportUntypedBaseClass.

---
 client/schemas/pyrightconfig.schema.json |  6 ++++++
 docs/configuration.md                    |  2 ++
 server/src/analyzer/semanticAnalyzer.ts  |  6 ------
 server/src/analyzer/typeAnalyzer.ts      | 11 +++++++++++
 server/src/common/configOptions.ts       |  7 +++++++
 5 files changed, 26 insertions(+), 6 deletions(-)

diff --git a/client/schemas/pyrightconfig.schema.json b/client/schemas/pyrightconfig.schema.json
index 65b9de218..6d42ce1fd 100644
--- a/client/schemas/pyrightconfig.schema.json
+++ b/client/schemas/pyrightconfig.schema.json
@@ -121,6 +121,12 @@
       "title": "Controls reporting of class decorators without type annotations, which obscure class types",
       "default": "none"
     },
+    "reportUntypedBaseClass": {
+      "$id": "#/properties/reportUntypedBaseClass",
+      "$ref": "#/definitions/diagnostic",
+      "title": "Controls reporting of a base class of an unknown type, which obscures most type checking for the class",
+      "default": "none"
+    },
     "reportPrivateUsage": {
       "$id": "#/properties/reportPrivateUsage",
       "$ref": "#/definitions/diagnostic",
diff --git a/docs/configuration.md b/docs/configuration.md
index a368a9c26..ade1617cf 100644
--- a/docs/configuration.md
+++ b/docs/configuration.md
@@ -48,6 +48,8 @@ The following settings control pyright's diagnostic output (warnings or errors).
 
 **reportUntypedClassDecorator** [boolean or string, optional]: Generate or suppress diagnostics for class decorators that have no type annotations. These obscure the class type, defeating many type analysis features.
 
+**reportUntypedBaseClass** [boolean or string, optional]: Generate or suppress diagnostics for base classes whose type cannot be determined statically. These obscure the class type, defeating many type analysis features.
+
 **reportPrivateUsage** [boolean or string, optional]: Generate or suppress diagnostics for uses of private variables or functions outside of the class or module that declares them. Private variables and functions, by convention, are named starting with a single underscoe (“_”) character.
 
 
diff --git a/server/src/analyzer/semanticAnalyzer.ts b/server/src/analyzer/semanticAnalyzer.ts
index 81f79f6dd..ceca47ad5 100644
--- a/server/src/analyzer/semanticAnalyzer.ts
+++ b/server/src/analyzer/semanticAnalyzer.ts
@@ -203,12 +203,6 @@ export abstract class SemanticAnalyzer extends ParseTreeWalker {
                 }
             }
 
-            if (!argType.isAny()) {
-                if (argType.category !== TypeCategory.Class) {
-                    this._addError(`Argument to class must be a base class`, arg);
-                }
-            }
-
             classType.addBaseClass(argType, isMetaclass);
 
             if (!isMetaclass) {
diff --git a/server/src/analyzer/typeAnalyzer.ts b/server/src/analyzer/typeAnalyzer.ts
index bd5254a40..6e7f143a0 100644
--- a/server/src/analyzer/typeAnalyzer.ts
+++ b/server/src/analyzer/typeAnalyzer.ts
@@ -163,6 +163,17 @@ export class TypeAnalyzer extends ParseTreeWalker {
                 }
             }
 
+            if (this._fileInfo.configOptions.reportUntypedBaseClass !== 'none') {
+                if (argType instanceof UnknownType ||
+                        argType instanceof UnionType && argType.getTypes().some(t => t instanceof UnknownType)) {
+
+                    this._addDiagnostic(
+                        this._fileInfo.configOptions.reportUntypedBaseClass,
+                        `Base class type is unknown, obscuring type of derived class`,
+                        arg);
+                }
+            }
+
             if (classType.updateBaseClassType(index, argType)) {
                 this._setAnalysisChanged();
             }
diff --git a/server/src/common/configOptions.ts b/server/src/common/configOptions.ts
index 6a90d31e3..ebb4236bb 100644
--- a/server/src/common/configOptions.ts
+++ b/server/src/common/configOptions.ts
@@ -106,6 +106,9 @@ export class ConfigOptions {
     // Report untyped class decorators that obscure the class type?
     reportUntypedClassDecorator: DiagnosticLevel = 'none';
 
+    // Report untyped base class that obscure the class type?
+    reportUntypedBaseClass: DiagnosticLevel = 'none';
+
     // Report usage of private variables and functions outside of
     // the owning class or module?
     reportPrivateUsage: DiagnosticLevel = 'none';
@@ -250,6 +253,10 @@ export class ConfigOptions {
         this.reportUntypedClassDecorator = this._convertDiagnosticLevel(
             configObj.reportUntypedClassDecorator, 'reportUntypedClassDecorator', 'none');
 
+        // Read the "reportUntypedBaseClass" entry.
+        this.reportUntypedBaseClass = this._convertDiagnosticLevel(
+            configObj.reportUntypedBaseClass, 'reportUntypedBaseClass', 'none');
+
         // Read the "reportPrivateUsage" entry.
         this.reportPrivateUsage = this._convertDiagnosticLevel(
             configObj.reportPrivateUsage, 'reportPrivateUsage', 'none');