Fix the emit when jsx attribute expression is empty

Fixes #12994

Author: sheetalkamat

src/compiler/transformers/jsx.ts

@@ -150,6 +150,9 @@ namespace ts {
                 return decoded ? createLiteral(decoded, /*location*/ node) : node;
             }
             else if (node.kind === SyntaxKind.JsxExpression) {
+                if (node.expression === undefined) {
+                    return createLiteral(true);
+                }
                 return visitJsxExpression(<JsxExpression>node);
             }
             else {

tests/baselines/reference/jsxAttributeWithoutExpressionReact.errors.txt

@@ -0,0 +1,33 @@
+tests/cases/compiler/jsxAttributeWithoutExpressionReact.tsx(3,2): error TS2304: Cannot find name 'View'.
+tests/cases/compiler/jsxAttributeWithoutExpressionReact.tsx(4,6): error TS2304: Cannot find name 'ListView'.
+tests/cases/compiler/jsxAttributeWithoutExpressionReact.tsx(5,10): error TS2304: Cannot find name 'RefreshControl'.
+tests/cases/compiler/jsxAttributeWithoutExpressionReact.tsx(5,35): error TS17000: JSX attributes must only be assigned a non-empty 'expression'.
+tests/cases/compiler/jsxAttributeWithoutExpressionReact.tsx(6,44): error TS17000: JSX attributes must only be assigned a non-empty 'expression'.
+tests/cases/compiler/jsxAttributeWithoutExpressionReact.tsx(7,7): error TS2304: Cannot find name 'ListView'.
+tests/cases/compiler/jsxAttributeWithoutExpressionReact.tsx(8,3): error TS2304: Cannot find name 'View'.
+
+
+==== tests/cases/compiler/jsxAttributeWithoutExpressionReact.tsx (7 errors) ====
+    
+    declare var React: any;
+    <View>
+     ~~~~
+!!! error TS2304: Cannot find name 'View'.
+        <ListView refreshControl={
+         ~~~~~~~~
+!!! error TS2304: Cannot find name 'ListView'.
+            <RefreshControl onRefresh={} refreshing={} />
+             ~~~~~~~~~~~~~~
+!!! error TS2304: Cannot find name 'RefreshControl'.
+                                      ~~
+!!! error TS17000: JSX attributes must only be assigned a non-empty 'expression'.
+        } dataSource={this.state.ds} renderRow={}>
+                                               ~~
+!!! error TS17000: JSX attributes must only be assigned a non-empty 'expression'.
+        </ListView>
+          ~~~~~~~~
+!!! error TS2304: Cannot find name 'ListView'.
+    </View>
+      ~~~~
+!!! error TS2304: Cannot find name 'View'.
+    

tests/baselines/reference/jsxAttributeWithoutExpressionReact.js

@@ -0,0 +1,14 @@
+//// [jsxAttributeWithoutExpressionReact.tsx]
+
+declare var React: any;
+<View>
+    <ListView refreshControl={
+        <RefreshControl onRefresh={} refreshing={} />
+    } dataSource={this.state.ds} renderRow={}>
+    </ListView>
+</View>
+
+
+//// [jsxAttributeWithoutExpressionReact.js]
+React.createElement(View, null,
+    React.createElement(ListView, { refreshControl: React.createElement(RefreshControl, { onRefresh: true, refreshing: true }), dataSource: this.state.ds, renderRow: true }));

tests/cases/compiler/jsxAttributeWithoutExpressionReact.tsx

@@ -0,0 +1,9 @@
+//@jsx: react
+
+declare var React: any;
+<View>
+    <ListView refreshControl={
+        <RefreshControl onRefresh={} refreshing={} />
+    } dataSource={this.state.ds} renderRow={}>
+    </ListView>
+</View>