Keen Yee Liau 5516802142 fix(compiler): avoid undefined expressions in holey array (#36343)
From G3 bug ID: 116443331

The View Engine compiler crashes when it tries to compile a test in JIT mode
that includes the d3-scale-chromatic library [1]. The d3 package initializes
some arrays using the following pattern:

```js
export var scheme = new Array(3).concat(
  "d8b365f5f5f55ab4ac",
  // ... more entries
).map(colors);
```

The stack trace from the crash is as follows:

```
TypeError: Cannot read property 'visitExpression' of undefined
    at ../../../third_party/javascript/angular2/rc/packages/compiler/src/output/abstract_emitter.ts:505:39
    at JitEmitterVisitor.AbstractEmitterVisitor.visitAllObjects third_party/javascript/angular2/rc/packages/compiler/src/output/abstract_emitter.ts?l=526
    at JitEmitterVisitor.AbstractEmitterVisitor.visitAllExpressions third_party/javascript/angular2/rc/packages/compiler/src/output/abstract_emitter.ts?l=505
    at JitEmitterVisitor.AbstractEmitterVisitor.visitLiteralArrayExpr third_party/javascript/angular2/rc/packages/compiler/src/output/abstract_emitter.ts?l=484
    at LiteralArrayExpr.visitExpression third_party/javascript/angular2/rc/packages/compiler/src/output/output_ast.ts?l=791
    at ../../../third_party/javascript/angular2/rc/packages/compiler/src/output/abstract_emitter.ts:492:19
    at JitEmitterVisitor.AbstractEmitterVisitor.visitAllObjects third_party/javascript/angular2/rc/packages/compiler/src/output/abstract_emitter.ts?l=526
    at JitEmitterVisitor.AbstractEmitterVisitor.visitLiteralMapExpr third_party/javascript/angular2/rc/packages/compiler/src/output/abstract_emitter.ts?l=490
    at LiteralMapExpr.visitExpression third_party/javascript/angular2/rc/packages/compiler/src/output/output_ast.ts?l=819
    at ../../../third_party/javascript/angular2/rc/packages/compiler/src/output/abstract_emitter.ts:505:39
    at JitEmitterVisitor.AbstractEmitterVisitor.visitAllObjects third_party/javascript/angular2/rc/packages/compiler/src/output/abstract_emitter.ts?l=526
    at JitEmitterVisitor.AbstractEmitterVisitor.visitAllExpressions third_party/javascript/angular2/rc/packages/compiler/src/output/abstract_emitter.ts?l=505
    at JitEmitterVisitor.AbstractEmitterVisitor.visitInvokeFunctionExpr third_party/javascript/angular2/rc/packages/compiler/src/output/abstract_emitter.ts?l=318
    at JitEmitterVisitor.AbstractJsEmitterVisitor.visitInvokeFunctionExpr third_party/javascript/angular2/rc/packages/compiler/src/output/abstract_js_emitter.ts?l=112
    at InvokeFunctionExpr.visitExpression third_party/javascript/angular2/rc/packages/compiler/src/output/output_ast.ts?l=440
```

This is because the corresponding output AST for the array is of the form

```ts
[
  undefined,
  undefined,
  undefined,
  o.LiteralExpr,
  // ...
]
```

The output AST is clearly malformed and breaks the type representation of
`LiteralArrayExpr` in which every entry is expected to be of type `Expression`.

This commit fixes the bug by using a plain `for` loop to iterate over the
entire length of the holey array and convert undefined elements to
`LiteralExpr`.

[1]: https://github.com/d3/d3-scale-chromatic/blob/master/src/diverging/BrBG.js

PR Close #36343
2020-04-01 13:31:14 -07:00
..
2020-01-13 07:21:43 -08:00

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