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fix(36936): tsc crashes with: Cannot read property 'get' of undefined#37077

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sandersn merged 1 commit intomicrosoft:masterfrom
a-tarasyuk:bug/36936
Mar 17, 2020
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fix(36936): tsc crashes with: Cannot read property 'get' of undefined#37077
sandersn merged 1 commit intomicrosoft:masterfrom
a-tarasyuk:bug/36936

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@a-tarasyuk a-tarasyuk commented Feb 27, 2020

Fixes #36936

@a-tarasyuk a-tarasyuk marked this pull request as ready for review February 27, 2020 19:06
@sandersn sandersn added the For Milestone Bug PRs that fix a bug with a specific milestone label Mar 9, 2020
@sandersn sandersn requested a review from andrewbranch March 9, 2020 23:22
@sandersn sandersn requested a review from weswigham March 10, 2020 22:49
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weswigham approved these changes Mar 10, 2020
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I'm OK with the change as-is, but it'd be nicer to track down why we're calling resolveExternalModuleSymbol on a symbol with no exports instead. Generally speaking, we only call that on a symbol we know to be a module, which, by extension, has exports. So the "real" fix for the underlying issue probably should be tracking down where we fail to give exports to a module-ish symbol.

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a-tarasyuk commented Mar 11, 2020

@weswigham You are right. Sorry that I didn't provide more details. I was able to reproduce the bug by debugging the checker. The issue in the interface property, in my case it called Test. I'm not sure that adding an additional condition in resolveExternalModuleSymbol is the right fix for this case, maybe resolveAlias should not return property Test.

getAccessibleSymbolChain -> forEachSymbolTableInScope

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For this case forEachSymbolTableInScope returns location.locals

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Test is the name from import statement

getAccessibleSymbolChainFromSymbolTable -> trySymbolTable

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For the Test symbol, resolveAlias returns a reference to the Test property which is declared inside interface Foo

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Then getCandidateListForSymbol ->
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-> getExportsOfSymbol -> getExportsOfModule -> getExportsOfModuleWorker
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And finally in resolveExternalModuleSymbol we get moduleSymbol without exports.

@sandersn sandersn merged commit a510cad into microsoft:master Mar 17, 2020
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tsc crashes with: Cannot read property 'get' of undefined

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