In https://github.com/babel/babel/issues/9511 (and #9495 is another symptom), @PavelKastornyy reported a node crash becaue the JavaScript heap run out of memory. The problem was that their code was adding enumerable properties to `Object.prototype`: it is something that shouldn't be done, but Babel shouldn't make node crash if someone adds them.
I reduced down the problem to `for...in` loops in `@babel/traverse` that grew the memory consumption exponentially because of that unexpected properties.
* Return inserted/replaced paths
This gives `Path`’s replacement and insertion methods a consistent
return value: the inserted/replaced paths.
Before, they could return `undefined`, a `node`, or a the current path
inside an array. It was kinda pointless. But now they always return an
array of paths, which is useful for solving
https://github.com/babel/babel/pull/4935#discussion_r96151368.
* Return inserted nodes and not BlockStatement
Addded test for bug #4363
* Cleanups
- `#replaceWith` will now return the current path if it's the same node
- `#insertAfter` and `#insertBefore` use public Path APIs now
- Makes container insertion faster (single splice call)
- Use public APIs in container insertion
- Replacing a statement with an expression returns the expression's path
- Replacing an expression with multiple statements returns the inserted
closure's body's paths.
* Handle arrow function processing via shared API rather than default plugin.
* Fix a few small PR comments.
* Preserve existing spec arrow 'this' rewrites, and support spec in subclass constructors.
Original PR: https://github.com/babel/babel/pull/2469. Seems this got
lost in the v6 changes.
- - -
Without this, the only way to replace the arrow function is to either
manually override its `node.body`, or duplicate the arrow:
```js
// Old
ArrowFunctionExpression: function (node) {
node.body = t.blockStatement(...);
// Or
return t.ArrowFunctionExpression(
node.params,
t.blockStatement(...),
node.async
);
}
// New
ArrowFunctionExpression: function() {
this.get("body").replaceWith(t.blockStatement(...));
}
```
Removed `@flow` annotation from files that don't actually pass Flow check at the moment. These will be added back file by file once the files are properly converted to use Flow.
Closes#3064
I'm extremely stupid and didn't commit as I go. To anyone reading this
I'm extremely sorry. A lot of these changes are very broad and I plan on
releasing Babel 6.0.0 today live on stage at Ember Camp London so I'm
afraid I couldn't wait. If you're ever in London I'll buy you a beer
(or assorted beverage!) to make up for it, also I'll kiss your feet and
give you a back massage, maybe.
