Improved parse recovery for ternary expressions that are missing an `…

…else` or a post-else expression. This addresses microsoft/pylance-release#3635.
microsoft · Nov 16, 2022 · 8b2f908 · 8b2f908
1 parent e9d29ce
commit 8b2f908
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Showing 2 changed files with 8 additions and 7 deletions.
diff --git a/packages/pyright-internal/src/parser/parser.ts b/packages/pyright-internal/src/parser/parser.ts
@@ -3014,16 +3014,17 @@ export class Parser {
         }
 
         if (!this._consumeTokenIfKeyword(KeywordType.Else)) {
-            return this._handleExpressionParseError(
-                ErrorExpressionCategory.MissingElse,
-                Localizer.Diagnostic.expectedElse()
+            return TernaryNode.create(
+                ifExpr,
+                testExpr,
+                this._handleExpressionParseError(
+                    ErrorExpressionCategory.MissingElse,
+                    Localizer.Diagnostic.expectedElse()
+                )
             );
         }
 
         const elseExpr = this._parseTestExpression(/* allowAssignmentExpression */ true);
-        if (elseExpr.nodeType === ParseNodeType.Error) {
-            return elseExpr;
-        }
 
         return TernaryNode.create(ifExpr, testExpr, elseExpr);
     }

diff --git a/packages/pyright-internal/src/tests/typeEvaluator4.test.ts b/packages/pyright-internal/src/tests/typeEvaluator4.test.ts
@@ -88,7 +88,7 @@ test('Metaclass9', () => {
 
 test('AssignmentExpr1', () => {
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['assignmentExpr1.py']);
-    TestUtils.validateResults(analysisResults, 5);
+    TestUtils.validateResults(analysisResults, 7);
 });
 
 test('AssignmentExpr2', () => {