C#: Deprecate Assignable(Read)::getAReachableRead

csharp/ql/src/Useless code/DefaultToStringQuery.qll

@@ -6,6 +6,7 @@ import semmle.code.csharp.frameworks.System
  * Holds if expression `e`, of type `t`, invokes `ToString()` either explicitly
  * or implicitly.
  */
+pragma[nomagic]
 predicate invokesToString(Expr e, ValueOrRefType t) {
   // Explicit invocation
   exists(MethodCall mc | mc.getQualifier() = e |
@@ -20,20 +21,24 @@ predicate invokesToString(Expr e, ValueOrRefType t) {
   // Implicit invocation via forwarder method
   t = e.stripCasts().getType() and
   not t instanceof StringType and
-  exists(Parameter p |
-    alwaysInvokesToStringOnParameter(p) and
+  exists(AssignableDefinitions::ImplicitParameterDefinition def, Parameter p |
+    def.getParameter() = p and
+    alwaysInvokesToString(def.getAFirstRead()) and
     e = p.getAnAssignedArgument()
   )
 }
 
-pragma[noinline]
-private predicate alwaysInvokesToStringOnParameter(Parameter p) {
-  exists(AssignableDefinitions::ImplicitParameterDefinition def, ParameterRead pr |
-    def.getParameter() = p and
-    pr = def.getAReachableRead() and
-    pr.getAControlFlowNode().postDominates(p.getCallable().getEntryPoint()) and
-    invokesToString(pr, _)
-  )
+pragma[nomagic]
+private predicate parameterReadPostDominatesEntry(ParameterRead pr) {
+  pr.getAControlFlowNode().postDominates(pr.getEnclosingCallable().getEntryPoint())
+}
+
+pragma[nomagic]
+private predicate alwaysInvokesToString(ParameterRead pr) {
+  parameterReadPostDominatesEntry(pr) and
+  invokesToString(pr, _)
+  or
+  alwaysInvokesToString(pr.getANextRead())
 }
 
 /**