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@yoff yoff commented Jan 9, 2026

It should be easy enough to ad tuple element (although these should take an index) and set element. List element was added in response to a user question. The change is trivial as it simply maps to the already supported subscript.

@yoff yoff requested a review from a team as a code owner January 9, 2026 12:10
Copilot AI review requested due to automatic review settings January 9, 2026 12:10
@github-actions github-actions bot added the Python label Jan 9, 2026
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Pull request overview

This PR adds support for the ListElement token in Models as Data (MaD) for Python, enabling users to specify list element access in data flow models. The implementation maps ListElement to the existing subscript functionality, reusing infrastructure already in place for list element content.

Key changes:

  • Enabled ListElement token in MaD access paths by treating it the same as DictionaryElementAny
  • Updated test case to verify list element source detection works correctly
  • Added ListElement to the list of valid tokens for identifying access paths

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File Description
python/ql/test/library-tests/frameworks/data/test.ext.yml Uncommented test case for ListElement to validate the new functionality
python/ql/test/library-tests/frameworks/data/test.expected Added expected test output showing that list element sources are now detected
python/ql/lib/semmle/python/frameworks/data/internal/ApiGraphModelsSpecific.qll Added ListElement support to token handling predicates, mapping it to subscript access

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# test steps through content
- ["testlib", "Member[source_dict].DictionaryElement[key].Member[func].ReturnValue", "test-source"]
- ["testlib", "Member[source_dict_any].DictionaryElementAny.Member[func].ReturnValue", "test-source"]
# TODO: Add support for list/tuples
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The TODO comment should be updated to reflect that list support has now been added. Consider changing it to "TODO: Add support for tuples" since only tuple support remains unimplemented.

Suggested change
# TODO: Add support for list/tuples
# TODO: Add support for tuples

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I think this looks very reasonable, modulo a small issue of naming that I just want to make sure we've thought about. 🙂

*/
predicate isExtraValidNoArgumentTokenInIdentifyingAccessPath(string name) {
name = ["Instance", "Awaited", "Call", "Subclass", "DictionaryElementAny"]
name = ["Instance", "Awaited", "Call", "Subclass", "DictionaryElementAny", "ListElement"]
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I feel like we may have had this discussion before, but should this instead be ListElementAny? Or is it safe to overload ListElement if we want to have more fine-grained control over the index later on?

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I did consider this and initially paused. I then noticed that no other language is using ListElement, so there is no conflicting semantics, at least.
We have several choices for how to take this, including adding ListElementAny or supporting ListElement[any] to be the same as just ListElement.

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Alright, let's just go with the current implementation, then. No need to complicate things.

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