Merge pull request #19269 from jketema/non-second-level-limits

C++: Do not limit second level scopes to the top-level

Author: jketema

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/DataFlowImplSpecific.qll

@@ -31,4 +31,6 @@ module CppDataFlow implements InputSig<Location> {
   predicate viableImplInCallContext = Private::viableImplInCallContext/2;
 
   predicate neverSkipInPathGraph = Private::neverSkipInPathGraph/1;
+
+  int defaultFieldFlowBranchLimit() { result = 3 }
 }

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/DataFlowPrivate.qll

@@ -1652,8 +1652,6 @@ predicate validParameterAliasStep(Node node1, Node node2) {
   )
 }
 
-private predicate isTopLevel(Cpp::Stmt s) { any(Function f).getBlock().getAStmt() = s }
-
 private Cpp::Stmt getAChainedBranch(Cpp::IfStmt s) {
   result = s.getThen()
   or
@@ -1684,11 +1682,9 @@ private Instruction getAnInstruction(Node n) {
 }
 
 private newtype TDataFlowSecondLevelScope =
-  TTopLevelIfBranch(Cpp::Stmt s) {
-    exists(Cpp::IfStmt ifstmt | s = getAChainedBranch(ifstmt) and isTopLevel(ifstmt))
-  } or
+  TTopLevelIfBranch(Cpp::Stmt s) { s = getAChainedBranch(_) } or
   TTopLevelSwitchCase(Cpp::SwitchCase s) {
-    exists(Cpp::SwitchStmt switchstmt | s = switchstmt.getASwitchCase() and isTopLevel(switchstmt))
+    exists(Cpp::SwitchStmt switchstmt | s = switchstmt.getASwitchCase())
   }
 
 /**