Merge pull request #21134 from yoff/python/support-ListElement-in-MaD

Python support `ListElement` in MaD

Author: tausbn

python/ql/lib/change-notes/2026-01-20-support-ListElement-in-python-MaD.md

@@ -0,0 +1,4 @@
+---
+category: feature
+---
+* It is now possible to refer to list elements in the Python models-as-data language, via the `ListElement` path.

python/ql/lib/semmle/python/frameworks/data/internal/ApiGraphModelsSpecific.qll

@@ -142,15 +142,13 @@ API::Node getExtraSuccessorFromNode(API::Node node, AccessPathTokenBase token) {
   // `DataFlow::DictionaryElementContent` just from seeing a subscript read, so we would
   // need to add that. (also need to handle things like `DictionaryElementAny` which
   // doesn't have any value for .getAnArgument())
-  (
-    token.getName() = "DictionaryElement" and
-    result = node.getSubscript(token.getAnArgument())
-    or
-    token.getName() = "DictionaryElementAny" and
-    result = node.getASubscript() and
-    not exists(token.getAnArgument())
-    // TODO: ListElement/SetElement/TupleElement
-  )
+  token.getName() = "DictionaryElement" and
+  result = node.getSubscript(token.getAnArgument())
+  or
+  token.getName() in ["DictionaryElementAny", "ListElement"] and
+  result = node.getASubscript() and
+  not exists(token.getAnArgument())
+  // TODO: SetElement/TupleElement
   // Some features don't have MaD tokens yet, they would need to be added to API-graphs first.
   // - decorators ("DecoratedClass", "DecoratedMember", "DecoratedParameter")
 }
@@ -261,7 +259,7 @@ predicate isExtraValidTokenNameInIdentifyingAccessPath(string name) {
   name =
     [
       "Member", "Instance", "Awaited", "Call", "Method", "Subclass", "DictionaryElement",
-      "DictionaryElementAny"
+      "DictionaryElementAny", "ListElement"
     ]
 }
 
@@ -270,7 +268,7 @@ predicate isExtraValidTokenNameInIdentifyingAccessPath(string name) {
  * in an identifying access path.
  */
 predicate isExtraValidNoArgumentTokenInIdentifyingAccessPath(string name) {
-  name = ["Instance", "Awaited", "Call", "Subclass", "DictionaryElementAny"]
+  name = ["Instance", "Awaited", "Call", "Subclass", "DictionaryElementAny", "ListElement"]
 }
 
 /**

python/ql/test/library-tests/frameworks/data/test.expected

@@ -108,6 +108,7 @@ isSource
 | test.py:119:20:119:30 | ControlFlowNode for getSource() | test-source |
 | test.py:124:1:124:33 | ControlFlowNode for Attribute() | test-source |
 | test.py:126:11:126:43 | ControlFlowNode for Attribute() | test-source |
+| test.py:129:11:129:39 | ControlFlowNode for Attribute() | test-source |
 syntaxErrors
 | Member[foo |
 | Member[foo] .Member[bar] |

python/ql/test/library-tests/frameworks/data/test.ext.yml

@@ -27,7 +27,7 @@ extensions:
       - ["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
-      # - ["testlib", "Member[source_list].ListElement.Member[func].ReturnValue", "test-source"]
+      - ["testlib", "Member[source_list].ListElement.Member[func].ReturnValue", "test-source"]
       # - ["testlib", "Member[source_tuple].TupleElement[0].Member[func].ReturnValue", "test-source"]
 
   - addsTo: