JavaScript: Teach Function.isGenerator to check for yield.#1110
Merged
semmle-qlci merged 1 commit intogithub:masterfrom Mar 14, 2019
Merged
JavaScript: Teach Function.isGenerator to check for yield.#1110semmle-qlci merged 1 commit intogithub:masterfrom
Function.isGenerator to check for yield.#1110semmle-qlci merged 1 commit intogithub:masterfrom
Conversation
asger-semmle
approved these changes
Mar 14, 2019
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
3 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Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be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.
We support
yieldin non-generator functions (a legacy Mozilla feature), which leads to false positives from some of our type-inference based queries as shown in the attached test: the type inference thinksinnerreturnsundefined, and hence flags the property access on its result. In fact,inneris (implicitly) a generator, so it doesn't returnundefinedat all.Fixed by extending
Function::isGeneratorto check for this case. While that's technically a breaking API change it can only affect custom queries for projects using legacy Mozilla features, of which there are none, as far as I know.I've tested this on
rhino, where it fixes 56 FPs at no performance cost.