From f7932dc1dfc01f331d18c86998e0d0a29367c42d Mon Sep 17 00:00:00 2001
From: Anders Schack-Mulligen <aschackmull@github.com>
Date: Fri, 22 Nov 2024 10:18:32 +0100
Subject: [PATCH] Dataflow: Postpone type pruning until stage 5.

---
 .../codeql/dataflow/internal/DataFlowImpl.qll         | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/shared/dataflow/codeql/dataflow/internal/DataFlowImpl.qll b/shared/dataflow/codeql/dataflow/internal/DataFlowImpl.qll
index 752733496ddbe..3eddbddf36cec 100644
--- a/shared/dataflow/codeql/dataflow/internal/DataFlowImpl.qll
+++ b/shared/dataflow/codeql/dataflow/internal/DataFlowImpl.qll
@@ -3929,7 +3929,7 @@ module MakeImpl<LocationSig Location, InputSig<Location> Lang> {
     private module Stage4Param implements MkStage<Stage3>::StageParam {
       private module PrevStage = Stage3;
 
-      class Typ = DataFlowType;
+      class Typ = Unit;
 
       class Ap = AccessPathFront;
 
@@ -3937,7 +3937,7 @@ module MakeImpl<LocationSig Location, InputSig<Location> Lang> {
 
       PrevStage::Ap getApprox(Ap ap) { result = ap.toApprox() }
 
-      Typ getTyp(DataFlowType t) { result = t }
+      Typ getTyp(DataFlowType t) { any() }
 
       bindingset[c, tail]
       Ap apCons(Content c, Ap tail) { result.getHead() = c and exists(tail) }
@@ -3962,9 +3962,10 @@ module MakeImpl<LocationSig Location, InputSig<Location> Lang> {
         NodeEx node1, FlowState state1, NodeEx node2, FlowState state2, boolean preservesValue,
         Typ t, LocalCc lcc, string label
       ) {
-        Stage3Param::localFlowBigStep(node1, state1, node2, state2, preservesValue, t, _, label) and
+        Stage3Param::localFlowBigStep(node1, state1, node2, state2, preservesValue, _, _, label) and
         PrevStage::revFlow(node1, pragma[only_bind_into](state1), _) and
         PrevStage::revFlow(node2, pragma[only_bind_into](state2), _) and
+        exists(t) and
         exists(lcc)
       }
 
@@ -4013,7 +4014,7 @@ module MakeImpl<LocationSig Location, InputSig<Location> Lang> {
       predicate filter(NodeEx node, FlowState state, Typ t0, Ap ap, Typ t) {
         exists(state) and
         not clear(node, ap) and
-        strengthenType(node, t0, t) and
+        t0 = t and
         (
           notExpectsContent(node)
           or
@@ -4027,7 +4028,7 @@ module MakeImpl<LocationSig Location, InputSig<Location> Lang> {
       }
 
       bindingset[t1, t2]
-      predicate typecheck(Typ t1, Typ t2) { compatibleTypesFilter(t1, t2) }
+      predicate typecheck(Typ t1, Typ t2) { any() }
     }
 
     private module Stage4 = MkStage<Stage3>::Stage<Stage4Param>;