Fix various issues with TS workaround #76
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This was referenced Nov 17, 2020
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Fixes #72
Background
TypeScript type elision breaks when we transform an
ImportDeclaration,ExportDeclaration, or the child propertymoduleSpecifieron either of the former. (see: microsoft/TypeScript#40603). This resulted in type exports being output in resulting js output instead of the normal elision behaviour.To work around this, we used
ts.updateNodein TS <4. In version 4+, however, this method was removed.Our first attempt at a new workaround was successful at restoring elision, however, it would break in instances where specific node-based information such as diagnostics were still referenced elsewhere. This is because we circumvented the API to directly replace the
moduleSpecifierproperty with a newly createdStringLiteral.Fix Detail
We are now using the new
updateNodemethod of the transformer factory API (which replaces the formergetMutableClone) in order to perform a somewhat lower-level replacement which does not cause elision functionality to break.In the future, if microsoft/TypeScript#40603 is resolved, we can switch to regular factory functions associated with updating the node types in question.
For now, however, this seems to work.
I've also added several specific tests for type elision functionality to ensure that this is checked in our build pipeline