Java: Replace getAFirstUse with top-level predicate.

Author: aschackmull

java/ql/lib/semmle/code/java/dataflow/SSA.qll

@@ -140,6 +140,14 @@ class SsaSourceField extends SsaSourceVariable {
   }
 }
 
+/**
+ * Gets an access of the SSA source variable underlying this SSA variable
+ * that can be reached from this SSA variable without passing through any
+ * other uses, but potentially through phi nodes and uncertain implicit
+ * updates.
+ */
+VarRead ssaGetAFirstUse(SsaDefinition def) { firstUse(def, result) }
+
 /**
  * An SSA variable.
  */
@@ -170,6 +178,8 @@ class SsaVariable extends Definition {
   VarRead getAUse() { result = getAUse(this) }
 
   /**
+   * DEPRECATED: Use `ssaGetAFirstUse(SsaDefinition)` instead.
+   *
    * Gets an access of the SSA source variable underlying this SSA variable
    * that can be reached from this SSA variable without passing through any
    * other uses, but potentially through phi nodes and uncertain implicit
@@ -178,7 +188,7 @@ class SsaVariable extends Definition {
    * Subsequent uses can be found by following the steps defined by
    * `adjacentUseUse`.
    */
-  VarRead getAFirstUse() { firstUse(this, result) }
+  deprecated VarRead getAFirstUse() { firstUse(this, result) }
 
   /** Holds if this SSA variable is live at the end of `b`. */
   predicate isLiveAtEndOfBlock(BasicBlock b) { ssaDefReachesEndOfBlock(b, this) }

java/ql/lib/semmle/code/java/dataflow/internal/ContainerFlow.qll

@@ -465,7 +465,7 @@ private predicate enhancedForStmtStep(Node node1, Node node2, Type containerType
     node1.asExpr() = e and
     containerType = e.getType() and
     v.getDefiningExpr() = for.getVariable() and
-    v.getAFirstUse() = node2.asExpr()
+    ssaGetAFirstUse(v) = node2.asExpr()
   )
 }
 

java/ql/lib/semmle/code/java/dataflow/internal/DataFlowPrivate.qll

@@ -401,7 +401,7 @@ class CastNode extends ExprNode {
           any(SwitchStmt ss).getExpr(), any(SwitchExpr se).getExpr(),
           any(InstanceOfExpr ioe).getExpr()
         ] and
-      this.asExpr() = upd.getAFirstUse()
+      this.asExpr() = ssaGetAFirstUse(upd)
     )
   }
 }

java/ql/lib/semmle/code/java/frameworks/InputStream.qll

@@ -45,7 +45,7 @@ private class InputStreamWrapperCapturedLocalStep extends AdditionalTaintStep {
       wrapper.getASourceSupertype+() instanceof TypeInputStream and
       m.getDeclaringType() = wrapper and
       capturer.captures(captured) and
-      TaintTracking::localTaint(DataFlow::exprNode(capturer.getAFirstUse()),
+      TaintTracking::localTaint(DataFlow::exprNode(ssaGetAFirstUse(capturer)),
         any(DataFlow::PostUpdateNode pun |
           pun.getPreUpdateNode().asExpr() = m.getParameter(0).getAnAccess()
         )) and

java/ql/lib/semmle/code/java/security/CommandArguments.qll

@@ -71,7 +71,7 @@ private class CommandArgumentList extends SsaExplicitUpdate {
 
   /** Gets a use of the variable for which the list could be empty. */
   private VarRead getAUseBeforeFirstAdd() {
-    result = this.getAFirstUse()
+    result = ssaGetAFirstUse(this)
     or
     exists(VarRead mid |
       mid = this.getAUseBeforeFirstAdd() and
@@ -150,7 +150,7 @@ private class CommandArgumentArray extends SsaExplicitUpdate {
 private class CommandArgArrayImmutableFirst extends CommandArgumentArray {
   CommandArgArrayImmutableFirst() {
     (exists(this.getAWrite(0)) or exists(firstElementOf(this.getDefiningExpr()))) and
-    forall(VarRead use | exists(this.getAWrite(0, use)) | use = this.getAFirstUse())
+    forall(VarRead use | exists(this.getAWrite(0, use)) | use = ssaGetAFirstUse(this))
   }
 
   /** Gets the first element of this array. */

java/ql/src/utils/modelgenerator/internal/CaptureModels.qll

@@ -279,7 +279,7 @@ private module SinkModelGeneratorInput implements SinkModelGeneratorInputSig {
     // exclude variable capture jump steps
     exists(Ssa::SsaImplicitInit closure |
       closure.captures(_) and
-      node.asExpr() = closure.getAFirstUse()
+      node.asExpr() = Ssa::ssaGetAFirstUse(closure)
     )
   }
 

java/ql/test/library-tests/ssa/firstUse.ql

@@ -1,6 +1,6 @@
 import java
 import semmle.code.java.dataflow.SSA
 
-from SsaVariable ssa, VarRead use
-where use = ssa.getAFirstUse()
+from SsaDefinition ssa, VarRead use
+where use = ssaGetAFirstUse(ssa)
 select ssa, use