Rust: Ensure index expressions are not handled as calls yet in data flow

Author: paldepind

rust/ql/lib/codeql/rust/dataflow/internal/DataFlowImpl.qll

@@ -145,9 +145,13 @@ final class ArgumentPosition extends ParameterPosition {
  * as the synthetic `ReceiverNode` is the argument for the `self` parameter.
  */
 predicate isArgumentForCall(ExprCfgNode arg, CallCfgNode call, ParameterPosition pos) {
-  call.getPositionalArgument(pos.getPosition()) = arg
-  or
-  call.getReceiver() = arg and pos.isSelf() and not call.getCall().receiverImplicitlyBorrowed()
+  // TODO: Handle index expressions as calls in data flow.
+  not call.getCall() instanceof IndexExpr and
+  (
+    call.getPositionalArgument(pos.getPosition()) = arg
+    or
+    call.getReceiver() = arg and pos.isSelf() and not call.getCall().receiverImplicitlyBorrowed()
+  )
 }
 
 /** Provides logic related to SSA. */

rust/ql/lib/codeql/rust/dataflow/internal/Node.qll

@@ -472,7 +472,11 @@ newtype TNode =
         getPostUpdateReverseStep(any(PostUpdateNode n).getPreUpdateNode().asExpr(), _)
       ]
   } or
-  TReceiverNode(CallCfgNode mc, Boolean isPost) { mc.getCall().receiverImplicitlyBorrowed() } or
+  TReceiverNode(CallCfgNode mc, Boolean isPost) {
+    mc.getCall().receiverImplicitlyBorrowed() and
+    // TODO: Handle index expressions as calls in data flow.
+    not mc.getCall() instanceof IndexExpr
+  } or
   TSsaNode(SsaImpl::DataFlowIntegration::SsaNode node) or
   TFlowSummaryNode(FlowSummaryImpl::Private::SummaryNode sn) or
   TClosureSelfReferenceNode(CfgScope c) { lambdaCreationExpr(c, _) } or