fix(compiler-core): elements with dynamic keys should be forced into blocks

fix #916

packages/compiler-core/__tests__/transforms/__snapshots__/hoistStatic.spec.ts.snap

@@ -292,10 +292,10 @@ exports[`compiler: hoistStatic transform should NOT hoist element with dynamic k
 
 return function render(_ctx, _cache) {
   with (_ctx) {
-    const { createVNode: _createVNode, openBlock: _openBlock, createBlock: _createBlock } = _Vue
+    const { openBlock: _openBlock, createBlock: _createBlock, createVNode: _createVNode } = _Vue
 
     return (_openBlock(), _createBlock(\\"div\\", null, [
-      _createVNode(\\"div\\", { key: foo })
+      (_openBlock(), _createBlock(\\"div\\", { key: foo }))
     ]))
   }
 }"

packages/compiler-core/__tests__/transforms/__snapshots__/vFor.spec.ts.snap

@@ -36,7 +36,7 @@ exports[`compiler: v-for codegen keyed v-for 1`] = `
 
 return function render(_ctx, _cache) {
   with (_ctx) {
-    const { renderList: _renderList, Fragment: _Fragment, openBlock: _openBlock, createBlock: _createBlock, createVNode: _createVNode } = _Vue
+    const { renderList: _renderList, Fragment: _Fragment, openBlock: _openBlock, createBlock: _createBlock } = _Vue
 
     return (_openBlock(true), _createBlock(_Fragment, null, _renderList(items, (item) => {
       return (_openBlock(), _createBlock(\\"span\\", { key: item }))

packages/compiler-core/__tests__/transforms/transformElement.spec.ts

@@ -861,4 +861,17 @@ describe('compiler: element transform', () => {
       isBlock: true
     })
   })
+
+  // #938
+  test('element with dynamic keys should be forced into blocks', () => {
+    const ast = parse(`<div><div :key="foo" /></div>`)
+    transform(ast, {
+      nodeTransforms: [transformElement]
+    })
+    expect((ast as any).children[0].children[0].codegenNode).toMatchObject({
+      type: NodeTypes.VNODE_CALL,
+      tag: `"div"`,
+      isBlock: true
+    })
+  })
 })