Properly disallow yield in bodyless arrows

src/compiler/parser.ts

@@ -5559,12 +5559,15 @@ namespace Parser {
             return parseFunctionBlock(SignatureFlags.IgnoreMissingOpenBrace | (isAsync ? SignatureFlags.Await : SignatureFlags.None));
         }
 
+        const savedYieldContext = inYieldContext();
+        setYieldContext(false);
         const savedTopLevel = topLevel;
         topLevel = false;
         const node = isAsync
             ? doInAwaitContext(() => parseAssignmentExpressionOrHigher(allowReturnTypeInArrowFunction))
             : doOutsideOfAwaitContext(() => parseAssignmentExpressionOrHigher(allowReturnTypeInArrowFunction));
         topLevel = savedTopLevel;
+        setYieldContext(savedYieldContext);
         return node;
     }
 

tests/baselines/reference/YieldExpression20_es6.errors.txt

@@ -0,0 +1,12 @@
+YieldExpression20_es6.ts(3,8): error TS1163: A 'yield' expression is only allowed in a generator body.
+
+
+==== YieldExpression20_es6.ts (1 errors) ====
+    function* test() {
+      return () => ({
+        b: yield 2, // error
+           ~~~~~
+!!! error TS1163: A 'yield' expression is only allowed in a generator body.
+      });
+    }
+

tests/baselines/reference/YieldExpression20_es6.js

@@ -0,0 +1,16 @@
+//// [tests/cases/conformance/es6/yieldExpressions/YieldExpression20_es6.ts] ////
+
+//// [YieldExpression20_es6.ts]
+function* test() {
+  return () => ({
+    b: yield 2, // error
+  });
+}
+
+
+//// [YieldExpression20_es6.js]
+function* test() {
+    return () => ({
+        b: yield 2, // error
+    });
+}

tests/baselines/reference/YieldExpression20_es6.symbols

@@ -0,0 +1,13 @@
+//// [tests/cases/conformance/es6/yieldExpressions/YieldExpression20_es6.ts] ////
+
+=== YieldExpression20_es6.ts ===
+function* test() {
+>test : Symbol(test, Decl(YieldExpression20_es6.ts, 0, 0))
+
+  return () => ({
+    b: yield 2, // error
+>b : Symbol(b, Decl(YieldExpression20_es6.ts, 1, 17))
+
+  });
+}
+

tests/baselines/reference/YieldExpression20_es6.types

@@ -0,0 +1,26 @@
+//// [tests/cases/conformance/es6/yieldExpressions/YieldExpression20_es6.ts] ////
+
+=== YieldExpression20_es6.ts ===
+function* test() {
+>test : () => Generator<never, () => { b: any; }, unknown>
+>     : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+  return () => ({
+>() => ({    b: yield 2, // error  }) : () => { b: any; }
+>                                     : ^^^^^^^^^^^^^^^^^
+>({    b: yield 2, // error  }) : { b: any; }
+>                               : ^^^^^^^^^^^
+>{    b: yield 2, // error  } : { b: any; }
+>                             : ^^^^^^^^^^^
+
+    b: yield 2, // error
+>b : any
+>  : ^^^
+>yield 2 : any
+>        : ^^^
+>2 : 2
+>  : ^
+
+  });
+}
+

tests/cases/conformance/es6/yieldExpressions/YieldExpression20_es6.ts

@@ -0,0 +1,7 @@
+// @target: es6
+
+function* test() {
+  return () => ({
+    b: yield 2, // error
+  });
+}