Python: gate captured jumps on SSA writes

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Author: yoff

python/ql/lib/semmle/python/dataflow/new/internal/TypeTrackingImpl.qll

@@ -324,10 +324,12 @@ module TypeTrackingInput implements Shared::TypeTrackingInput<Location> {
     // nodeFrom is `expr`
     // nodeTo is entry node for `f`
     exists(
-      SsaImpl::ScopeEntryDefinition e, SsaImpl::SsaSourceVariable var, Cfg::DefinitionNode def
+      SsaImpl::ScopeEntryDefinition e, SsaImpl::SsaSourceVariable var,
+      SsaImpl::EssaNodeDefinition write, Cfg::DefinitionNode def
     |
       e.getSourceVariable() = var and
-      def.getNode() = var.getVariable().getAStore()
+      write.getSourceVariable() = var and
+      write.getDefiningNode() = def
     |
       nodeTo.(DataFlowPublic::ScopeEntryDefinitionNode).getDefinition() = e and
       nodeFrom.asCfgNode() = def and

python/ql/test/library-tests/dataflow/typetracking/test.py

@@ -86,14 +86,14 @@ def captured_reassignment_tradeoff():
     value = tracked # $ tracked
 
     def read_value():
-        return value # $ tracked
+        return value # $ MISSING: tracked
 
-    before_reassignment = read_value() # $ tracked
+    before_reassignment = read_value() # $ MISSING: tracked
     value = "safe"
-    safe_sibling = read_value() # $ SPURIOUS: tracked
+    safe_sibling = read_value()
 
-    before_reassignment # $ tracked
-    safe_sibling # $ SPURIOUS: tracked
+    before_reassignment # $ MISSING: tracked
+    safe_sibling
 
 
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