[Fresh] Fall back to Map/Set if Weak equivalents are not available#15907
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gaearon merged 2 commits intofacebook:masterfrom Jun 17, 2019
Merged
[Fresh] Fall back to Map/Set if Weak equivalents are not available#15907gaearon merged 2 commits intofacebook:masterfrom
gaearon merged 2 commits intofacebook:masterfrom
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threepointone
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gaearon
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Jun 19, 2019
…acebook#15907) * Fall back to Map/Set if Weak equivalents are not available * Fix Prettier vs Flow fighting
rickhanlonii
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Jun 25, 2019
…acebook#15907) * Fall back to Map/Set if Weak equivalents are not available * Fix Prettier vs Flow fighting
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I'm running into this in an older RN environment. Modern ones look fine (including the today's RN open source). So this is a temporary solution until everything is modern internally.
We rely on
WeakMapandWeakSetto avoid holding onto previous versions of any type after a hot reload edit. So this change makes us leak some memory in old environments. I think it's fine because it only affects really old environments (e.g. IE) and the cost is DEV-only (and only comes into play if you actually do a hot reload).The Flow issues are the same we've ran into before. It's a Flow bug but I don't know if it'll get fixed.