From 1f4c8708c251eb0cce31ad527e50fd7a3a7ddae7 Mon Sep 17 00:00:00 2001
From: Oleksandr T <oleksandr.tarasiuk@outlook.com>
Date: Sat, 29 May 2021 00:42:09 +0300
Subject: [PATCH] fix(44123): forbid convert to async for generator callbacks
 (#44147)

---
 src/services/suggestionDiagnostics.ts                  |  5 +++++
 .../unittests/services/convertToAsyncFunction.ts       | 10 ++++++++++
 2 files changed, 15 insertions(+)

diff --git a/src/services/suggestionDiagnostics.ts b/src/services/suggestionDiagnostics.ts
index ade23ff29e7..09740f8f2ee 100644
--- a/src/services/suggestionDiagnostics.ts
+++ b/src/services/suggestionDiagnostics.ts
@@ -174,6 +174,11 @@ namespace ts {
         switch (arg.kind) {
             case SyntaxKind.FunctionDeclaration:
             case SyntaxKind.FunctionExpression:
+                const functionFlags = getFunctionFlags(arg as FunctionDeclaration | FunctionExpression);
+                if (functionFlags & FunctionFlags.Generator) {
+                    return false;
+                }
+                // falls through
             case SyntaxKind.ArrowFunction:
                 visitedNestedConvertibleFunctions.set(getKeyFromNode(arg as FunctionLikeDeclaration), true);
                 // falls through
diff --git a/src/testRunner/unittests/services/convertToAsyncFunction.ts b/src/testRunner/unittests/services/convertToAsyncFunction.ts
index fd2677b029e..d73877b259f 100644
--- a/src/testRunner/unittests/services/convertToAsyncFunction.ts
+++ b/src/testRunner/unittests/services/convertToAsyncFunction.ts
@@ -1706,6 +1706,16 @@ class Foo {
         return Promise.resolve(1).then(n => n);
     }
 }
+`);
+
+        _testConvertToAsyncFunctionFailed("convertToAsyncFunction__NoSuggestionForGeneratorCallbacks", `
+function [#|foo|](p: Promise<string[]>) {
+    return p.then(function* (strings) {
+        for (const s of strings) {
+            yield s.toUpperCase();
+        }
+    });
+}
 `);
 
     });