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[EXPERIMENT] Disable synthetic default imports when ambiguously safe #62530

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[EXPERIMENT] Disable synthetic default imports when ambiguously safe #62530

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b4be623
Disable synthetic default imports when ambiguously safe
andrewbranch Oct 2, 2025
6ee5131
Make a carve-out for node built-ins
andrewbranch Oct 2, 2025
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8 changes: 4 additions & 4 deletions src/compiler/checker.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -3806,10 +3806,10 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
// it definitely is a module and does not have a synthetic default
return false;
}
// There are _many_ declaration files not written with esmodules in mind that still get compiled into a format with __esModule set
// Meaning there may be no default at runtime - however to be on the permissive side, we allow access to a synthetic default member
// as there is no marker to indicate if the accompanying JS has `__esModule` or not, or is even native esm
return true;
if (!file && getSourceFileOfModule(moduleSymbol)?.fileName.includes("/@types/node/")) {
return true;
}
return hasExportAssignmentSymbol(moduleSymbol);
}
// TypeScript files never have a synthetic default (as they are always emitted with an __esModule marker) _unless_ they contain an export= statement
if (!isSourceFileJS(file)) {
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