Apply review suggestions: use ArgumentNode.argumentOf, and change more uses of ValuePreservingCallable -> ValuePreservingMethod

Author: smowton

java/ql/src/semmle/code/java/dataflow/FlowSteps.qll

@@ -46,14 +46,14 @@ abstract class ValuePreservingMethod extends Method {
  * These steps will be visible for all global data-flow purposes, as well as via
  * `DataFlow::Node.getASuccessor` and other related functions exposing intraprocedural dataflow.
  */
-abstract class FluentMethod extends ValuePreservingCallable {
+abstract class FluentMethod extends ValuePreservingMethod {
   override predicate returnsValue(int arg) { arg = -1 }
 }
 
 private class StandardLibraryValuePreservingMethod extends ValuePreservingMethod {
   int returnsArgNo;
 
-  StandardLibraryValuePreservingCallable() {
+  StandardLibraryValuePreservingMethod() {
     this.getDeclaringType().hasQualifiedName("java.util", "Objects") and
     (
       this.hasName(["requireNonNull", "requireNonNullElseGet"]) and returnsArgNo = 0
@@ -63,9 +63,7 @@ private class StandardLibraryValuePreservingMethod extends ValuePreservingMethod
       this.hasName("toString") and returnsArgNo = 1
     )
     or
-    this.getDeclaringType()
-        .getASourceSupertype*()
-        .hasQualifiedName("java.util", "Stack") and
+    this.getDeclaringType().getASourceSupertype*().hasQualifiedName("java.util", "Stack") and
     this.hasName("push") and
     returnsArgNo = 0
   }

java/ql/src/semmle/code/java/dataflow/internal/DataFlowUtil.qll

@@ -409,15 +409,11 @@ predicate simpleLocalFlowStep(Node node1, Node node2) {
   or
   summaryStep(node1, node2, "value")
   or
-  exists(MethodAccess ma, ValuePreservingCallable c, int argNo |
-    ma.getCallee().getSourceDeclaration() = c and c.returnsValue(argNo)
+  exists(MethodAccess ma, ValuePreservingMethod m, int argNo |
+    ma.getCallee().getSourceDeclaration() = m and m.returnsValue(argNo)
   |
     node2.asExpr() = ma and
-    (
-      node1.asExpr() = ma.getArgument(argNo)
-      or
-      argNo = -1 and node1.asExpr() = ma.getQualifier()
-    )
+    node1.(ArgumentNode).argumentOf(ma, argNo)
   )
 }
 

java/ql/test/library-tests/dataflow/fluent-methods/flow.ql

@@ -19,7 +19,7 @@ class Model extends FluentMethod {
   Model() { this.getName() = "modelledFluentMethod" }
 }
 
-class IdentityModel extends ValuePreservingCallable {
+class IdentityModel extends ValuePreservingMethod {
   IdentityModel() { this.getName() = "modelledIdentity" }
 
   override predicate returnsValue(int arg) { arg = 0 }