[Fix] guard toStringTag with correct ternary precedence#53
Merged
Conversation
The inner ternary `typeof Symbol.toStringTag === hasShammedSymbols ? 'object' : 'symbol'` compared `typeof` (a string) against `hasShammedSymbols` (a boolean), so it was always `false` and the expression was a constant truthy `'symbol'`. This defeated the sham-vs-native type validation; in a malformed Symbol sham where `Symbol.toStringTag` exists with the wrong type, downstream `toStringTag in obj` usage could misbehave. Co-Authored-By: Claude <noreply@anthropic.com> Co-Authored-By: DeepView Autofix <276251120+deepview-autofix@users.noreply.github.com> Co-Authored-By: Nikita Skovoroda <chalkerx@gmail.com> Co-Authored-By: Jordan Harband <ljharb@gmail.com> Signed-off-by: Nikita Skovoroda <chalkerx@gmail.com>
a37987f to
ca16eec
Compare
ljharb
approved these changes
Apr 24, 2026
ljharb
left a comment
Member
There was a problem hiding this comment.
added a test, and updated the lint config to require typeof comparisons to always be to string literals.
ca16eec to
012c719
Compare
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
The inner ternary
typeof Symbol.toStringTag === hasShammedSymbols ? 'object' : 'symbol'comparedtypeof(a string) againsthasShammedSymbols(a boolean), so it was alwaysfalseand the expression was a constant truthy'symbol'. This defeated the sham-vs-native type validation; in a malformed Symbol sham whereSymbol.toStringTagexists with the wrong type, downstreamtoStringTag in objusage could misbehave.