C++: Remove support for global variables as sources and sinks in MaD

cpp/ql/lib/change-notes/2026-06-30-variables-as-mad-sources-and-sinks.md

@@ -0,0 +1,4 @@
+---
+category: breaking
+---
+* Removed support for using variables as sources and sinks in models-as-data. Users of this feature should convert such sources and sinks to models defined using the QL language.

cpp/ql/lib/semmle/code/cpp/dataflow/ExternalFlow.qll

@@ -931,31 +931,6 @@ private Element interpretElement0(
     signature = "" and
     elementSpec(namespace, type, subtypes, name, signature, _)
   )
-  or
-  // Member variables
-  elementSpec(namespace, type, subtypes, name, signature, _) and
-  signature = "" and
-  exists(Class namedClass, Class classWithMember, MemberVariable member |
-    member.getName() = name and
-    member = classWithMember.getAMember() and
-    namedClass.hasQualifiedName(namespace, type) and
-    result = member
-  |
-    // field declared in the named type or a subtype of it (or an extension of any)
-    subtypes = true and
-    classWithMember = namedClass.getADerivedClass*()
-    or
-    // field declared directly in the named type (or an extension of it)
-    subtypes = false and
-    classWithMember = namedClass
-  )
-  or
-  // Global or namespace variables
-  elementSpec(namespace, type, subtypes, name, signature, _) and
-  signature = "" and
-  type = "" and
-  subtypes = false and
-  result = any(GlobalOrNamespaceVariable v | v.hasQualifiedName(namespace, name))
 }
 
 cached

cpp/ql/lib/semmle/code/cpp/dataflow/internal/FlowSummaryImpl.qll

@@ -230,40 +230,11 @@ module SourceSinkInterpretationInput implements
 
   /** Provides additional sink specification logic. */
   bindingset[c]
-  predicate interpretOutput(string c, InterpretNode mid, InterpretNode node) {
-    // Allow variables to be picked as output nodes.
-    exists(Node n, Element ast |
-      n = node.asNode() and
-      ast = mid.asElement()
-    |
-      c = "" and
-      n.asExpr().(VariableAccess).getTarget() = ast
-    )
-  }
+  predicate interpretOutput(string c, InterpretNode mid, InterpretNode node) { none() }
 
   /** Provides additional source specification logic. */
   bindingset[c]
-  predicate interpretInput(string c, InterpretNode mid, InterpretNode node) {
-    exists(Node n, Element ast, VariableAccess e |
-      n = node.asNode() and
-      ast = mid.asElement() and
-      e.getTarget() = ast
-    |
-      // Allow variables to be picked as input nodes.
-      // We could simply do this as `e = n.asExpr()`, but that would not allow
-      // us to pick `x` as a sink in an example such as `x = source()` (but
-      // only subsequent uses of `x`) since the variable access on `x` doesn't
-      // actually load the value of `x`. So instead, we pick the instruction
-      // node corresponding to the generated `StoreInstruction` and use the
-      // expression associated with the destination instruction. This means
-      // that the `x` in `x = source()` can be marked as an input.
-      c = "" and
-      exists(StoreInstruction store |
-        store.getDestinationAddress().getUnconvertedResultExpression() = e and
-        n.asInstruction() = store
-      )
-    )
-  }
+  predicate interpretInput(string c, InterpretNode mid, InterpretNode node) { none() }
 }
 
 module Private {