No contextual types from circular mapped type properties #38653
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We also do type resolution stack inspection for avoiding some circularities in JS checking, so we have some precedent for doing this. We probably need to monitor LS bug reports to to make sure this doesn't cause a bug in the category of thing-gets-contextual-type-if-mouseover-A-then-B-but-not-B-then-A. I don't think the results of this calculation should be cached anywhere, so it should be OK; but we should be vigilant in case we get a report that sounds like that.
* upstream/master: Support naming tuple members (microsoft#38234) LEGO: check in for master to temporary branch. fix: extract const in jsx (microsoft#37912) No contextual types from circular mapped type properties (microsoft#38653) Ensure formatter can always get a newline character (microsoft#38579) Fix debug command for Node debugging Remove mentions of runtests-browser in CONTRIBUTING.md fix(33233): add outlining for comments before property access expression regression(38485): allow using rawText property in processing a tagged template
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@typescript-bot cherry-pick this to release-3.9 |
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Heya @RyanCavanaugh, I've started to run the task to cherry-pick this into |
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Hey @RyanCavanaugh, I've opened #38687 for you. |
)" This reverts commit 9ec5fc5.
With this PR we no longer attempt to produce contextual types from mapped type properties that are circular. Specifically, in
getTypeOfPropertyOfContextualTypewe now check if the property originates in mapped type and if resolution of the type of the property would cause a circularity. If so, instead of resolving the type (which would produce a circularity error) we simply returnundefinedto indicate that there is no contextual type.I have added the simplified repro from #38279 to the tests, plus I have manually verified that each of the complex repros in that issue no longer error.
Fixes #38279.