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fix: coerce pollutes argv #2161
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Small nit, but this bug fix looks good to me.
Great digging @jly36963.
lib/yargs-factory.ts
Outdated
@@ -387,6 +387,13 @@ export class YargsInstance { | |||
yargs: YargsInstance | |||
): Partial<Arguments> | Promise<Partial<Arguments>> => { | |||
let aliases: Dictionary<string[]>; | |||
|
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// Skip coerce logic if related arg was not provided | |||
const shouldCoerce = Object.prototype.hasOwnProperty.call(argv, keys); |
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I believe this can just be:
Object.hasOwnProperty.call(obj, 'a')
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I'm afraid this is not correct and it should be Object.prototype.hasOwnProperty
.
The changes relating to this should be reverted.
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Object.hasOwnProperty.call({a: 5}, 'a')
and Object.prototype.hasOwnProperty.call({a: 5}, 'a')
both return true
. (I thought there might be an issue when using a null object, but both return false
when Object.create(null)
is used as the first argument.) I don't know of any scenarios where their behavior differs. Do you have an example where it could cause problems?
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Also, Object.hasOwnProperty.call === Object.prototype.hasOwnProperty.call
is true. I'm assuming they are a reference to the same object
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Notwithstanding the fact that this convention of using the prototype
instead of the Object
class directly is widely adopted.
It's the same reason to not use {a: 1}.hasOwnProperty('a')
. The function could have been overridden via a global polyfill or patch meaning you're not using native behaviour.
I assume that {}.hasOwnProperty.call === Object.hasOwnProperty.call
as well as the prototype. The point is that they can be overridden and are, thus, unreliable to use unless you use the underlying prototype.
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I mean, Object.prototype
can just as easily be overwritten:
> Object.prototype.hasOwnProperty = () => 'batman'
[Function (anonymous)]
> {}.hasOwnProperty()
'batman'
We would have to rewrite all of yargs to use primordials that are frozen at Node.js' startup to really avoid this issue.
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We would have to rewrite all of yargs to use primordials that are frozen at Node.js' startup to really avoid this issue.
This is how Node.js itself approaches the problem:
https://github.com/nodejs/node/blob/master/lib/internal/per_context/primordials.js
But it's made easier for them by the fact that they can do so during bootstrapping.
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Yeah, this is definitely not an issue that is limited to yargs
, for better or worse it's a language issue.
Whilst I think overriding the built-in methods like Object.hasOwnProperty()
is pretty crazy, for those crazy enough to do it I think there is enough expectation that the prototype is left alone that it can be used reliably. Hence why it's enforced by standard linting rules in eslint and recommendations elsewhere.
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@dhensby makes sense to me.
@jly36963 thank you for the great fix, we can likely close the affected PRs? |
Related
coerce
property inv17
#2162TLDR
Description
I'm fixing two coerce bugs:
Bug one
Details
Coerce doesn't behave correctly when the related arg is not passed.
There are two unintentional side-effects:
coerce > maybeAsyncResult > resultHandler
sets argv, which shouldn't happen.Reproduction
'b' was not provided, so:
argv
Bug two
Details
Coerce adds aliases to argv (even when strip-aliased is true)
Reproduction
b
should not be defined onargv