From 4b7813b98e8775ef9a15fe92ac2369f2e5bcc42c Mon Sep 17 00:00:00 2001
From: Jonas Jensen <jonas@semmle.com>
Date: Wed, 21 Aug 2019 09:27:01 +0200
Subject: [PATCH 1/4] C++/C#/Java: Split localFlowStep predicate in two

There's now a `localFlowStep` predicate for use directly in queries and
other libraries and a `simpleLocalFlowStep` for use only by the global
data flow library. The former predicate is intended to include field
flow, but the latter may not.

This will let Java and C# (and possibly C++ IR) avoid getting two kinds
of field flow at the same time, both from SSA and from the global data
flow library. It should let C++ AST add some form of field flow to
`localFlowStep` without making it an input to the global data flow
library.
---
 .../code/cpp/dataflow/internal/DataFlowImpl.qll      |  2 +-
 .../code/cpp/dataflow/internal/DataFlowImpl2.qll     |  2 +-
 .../code/cpp/dataflow/internal/DataFlowImpl3.qll     |  2 +-
 .../code/cpp/dataflow/internal/DataFlowImpl4.qll     |  2 +-
 .../code/cpp/dataflow/internal/DataFlowUtil.qll      | 12 +++++++++++-
 .../code/cpp/ir/dataflow/internal/DataFlowImpl.qll   |  2 +-
 .../code/cpp/ir/dataflow/internal/DataFlowImpl2.qll  |  2 +-
 .../code/cpp/ir/dataflow/internal/DataFlowImpl3.qll  |  2 +-
 .../code/cpp/ir/dataflow/internal/DataFlowImpl4.qll  |  2 +-
 .../code/cpp/ir/dataflow/internal/DataFlowUtil.qll   | 10 ++++++++++
 .../code/csharp/dataflow/internal/DataFlowImpl.qll   |  2 +-
 .../code/csharp/dataflow/internal/DataFlowImpl2.qll  |  2 +-
 .../code/csharp/dataflow/internal/DataFlowImpl3.qll  |  2 +-
 .../code/csharp/dataflow/internal/DataFlowImpl4.qll  |  2 +-
 .../code/csharp/dataflow/internal/DataFlowImpl5.qll  |  2 +-
 .../csharp/dataflow/internal/DataFlowPrivate.qll     | 11 +++++++++++
 .../code/java/dataflow/internal/DataFlowImpl.qll     |  2 +-
 .../code/java/dataflow/internal/DataFlowImpl2.qll    |  2 +-
 .../code/java/dataflow/internal/DataFlowImpl3.qll    |  2 +-
 .../code/java/dataflow/internal/DataFlowImpl4.qll    |  2 +-
 .../code/java/dataflow/internal/DataFlowImpl5.qll    |  2 +-
 .../code/java/dataflow/internal/DataFlowUtil.qll     | 11 +++++++++++
 22 files changed, 61 insertions(+), 19 deletions(-)

diff --git a/cpp/ql/src/semmle/code/cpp/dataflow/internal/DataFlowImpl.qll b/cpp/ql/src/semmle/code/cpp/dataflow/internal/DataFlowImpl.qll
index f797b3bcf35b..64edab03d692 100644
--- a/cpp/ql/src/semmle/code/cpp/dataflow/internal/DataFlowImpl.qll
+++ b/cpp/ql/src/semmle/code/cpp/dataflow/internal/DataFlowImpl.qll
@@ -162,7 +162,7 @@ private predicate isAdditionalFlowStep(
  * Holds if data can flow in one local step from `node1` to `node2`.
  */
 private predicate localFlowStep(Node node1, Node node2, Configuration config) {
-  localFlowStep(node1, node2) and
+  simpleLocalFlowStep(node1, node2) and
   not outBarrier(node1, config) and
   not inBarrier(node2, config) and
   not fullBarrier(node1, config) and
diff --git a/cpp/ql/src/semmle/code/cpp/dataflow/internal/DataFlowImpl2.qll b/cpp/ql/src/semmle/code/cpp/dataflow/internal/DataFlowImpl2.qll
index f797b3bcf35b..64edab03d692 100644
--- a/cpp/ql/src/semmle/code/cpp/dataflow/internal/DataFlowImpl2.qll
+++ b/cpp/ql/src/semmle/code/cpp/dataflow/internal/DataFlowImpl2.qll
@@ -162,7 +162,7 @@ private predicate isAdditionalFlowStep(
  * Holds if data can flow in one local step from `node1` to `node2`.
  */
 private predicate localFlowStep(Node node1, Node node2, Configuration config) {
-  localFlowStep(node1, node2) and
+  simpleLocalFlowStep(node1, node2) and
   not outBarrier(node1, config) and
   not inBarrier(node2, config) and
   not fullBarrier(node1, config) and
diff --git a/cpp/ql/src/semmle/code/cpp/dataflow/internal/DataFlowImpl3.qll b/cpp/ql/src/semmle/code/cpp/dataflow/internal/DataFlowImpl3.qll
index f797b3bcf35b..64edab03d692 100644
--- a/cpp/ql/src/semmle/code/cpp/dataflow/internal/DataFlowImpl3.qll
+++ b/cpp/ql/src/semmle/code/cpp/dataflow/internal/DataFlowImpl3.qll
@@ -162,7 +162,7 @@ private predicate isAdditionalFlowStep(
  * Holds if data can flow in one local step from `node1` to `node2`.
  */
 private predicate localFlowStep(Node node1, Node node2, Configuration config) {
-  localFlowStep(node1, node2) and
+  simpleLocalFlowStep(node1, node2) and
   not outBarrier(node1, config) and
   not inBarrier(node2, config) and
   not fullBarrier(node1, config) and
diff --git a/cpp/ql/src/semmle/code/cpp/dataflow/internal/DataFlowImpl4.qll b/cpp/ql/src/semmle/code/cpp/dataflow/internal/DataFlowImpl4.qll
index f797b3bcf35b..64edab03d692 100644
--- a/cpp/ql/src/semmle/code/cpp/dataflow/internal/DataFlowImpl4.qll
+++ b/cpp/ql/src/semmle/code/cpp/dataflow/internal/DataFlowImpl4.qll
@@ -162,7 +162,7 @@ private predicate isAdditionalFlowStep(
  * Holds if data can flow in one local step from `node1` to `node2`.
  */
 private predicate localFlowStep(Node node1, Node node2, Configuration config) {
-  localFlowStep(node1, node2) and
+  simpleLocalFlowStep(node1, node2) and
   not outBarrier(node1, config) and
   not inBarrier(node2, config) and
   not fullBarrier(node1, config) and
diff --git a/cpp/ql/src/semmle/code/cpp/dataflow/internal/DataFlowUtil.qll b/cpp/ql/src/semmle/code/cpp/dataflow/internal/DataFlowUtil.qll
index 8f8a7a9369a2..955208cacc6e 100644
--- a/cpp/ql/src/semmle/code/cpp/dataflow/internal/DataFlowUtil.qll
+++ b/cpp/ql/src/semmle/code/cpp/dataflow/internal/DataFlowUtil.qll
@@ -422,8 +422,18 @@ private module ThisFlow {
  * Holds if data flows from `nodeFrom` to `nodeTo` in exactly one local
  * (intra-procedural) step.
  */
-cached
 predicate localFlowStep(Node nodeFrom, Node nodeTo) {
+  simpleLocalFlowStep(nodeFrom, nodeTo)
+}
+
+/**
+ * INTERNAL: do not use.
+ *
+ * This is the local flow predicate that's used as a building block in global
+ * data flow. It may have less flow than the `localFlowStep` predicate.
+ */
+cached
+predicate simpleLocalFlowStep(Node nodeFrom, Node nodeTo) {
   // Expr -> Expr
   exprToExprStep_nocfg(nodeFrom.asExpr(), nodeTo.asExpr())
   or
diff --git a/cpp/ql/src/semmle/code/cpp/ir/dataflow/internal/DataFlowImpl.qll b/cpp/ql/src/semmle/code/cpp/ir/dataflow/internal/DataFlowImpl.qll
index f797b3bcf35b..64edab03d692 100644
--- a/cpp/ql/src/semmle/code/cpp/ir/dataflow/internal/DataFlowImpl.qll
+++ b/cpp/ql/src/semmle/code/cpp/ir/dataflow/internal/DataFlowImpl.qll
@@ -162,7 +162,7 @@ private predicate isAdditionalFlowStep(
  * Holds if data can flow in one local step from `node1` to `node2`.
  */
 private predicate localFlowStep(Node node1, Node node2, Configuration config) {
-  localFlowStep(node1, node2) and
+  simpleLocalFlowStep(node1, node2) and
   not outBarrier(node1, config) and
   not inBarrier(node2, config) and
   not fullBarrier(node1, config) and
diff --git a/cpp/ql/src/semmle/code/cpp/ir/dataflow/internal/DataFlowImpl2.qll b/cpp/ql/src/semmle/code/cpp/ir/dataflow/internal/DataFlowImpl2.qll
index f797b3bcf35b..64edab03d692 100644
--- a/cpp/ql/src/semmle/code/cpp/ir/dataflow/internal/DataFlowImpl2.qll
+++ b/cpp/ql/src/semmle/code/cpp/ir/dataflow/internal/DataFlowImpl2.qll
@@ -162,7 +162,7 @@ private predicate isAdditionalFlowStep(
  * Holds if data can flow in one local step from `node1` to `node2`.
  */
 private predicate localFlowStep(Node node1, Node node2, Configuration config) {
-  localFlowStep(node1, node2) and
+  simpleLocalFlowStep(node1, node2) and
   not outBarrier(node1, config) and
   not inBarrier(node2, config) and
   not fullBarrier(node1, config) and
diff --git a/cpp/ql/src/semmle/code/cpp/ir/dataflow/internal/DataFlowImpl3.qll b/cpp/ql/src/semmle/code/cpp/ir/dataflow/internal/DataFlowImpl3.qll
index f797b3bcf35b..64edab03d692 100644
--- a/cpp/ql/src/semmle/code/cpp/ir/dataflow/internal/DataFlowImpl3.qll
+++ b/cpp/ql/src/semmle/code/cpp/ir/dataflow/internal/DataFlowImpl3.qll
@@ -162,7 +162,7 @@ private predicate isAdditionalFlowStep(
  * Holds if data can flow in one local step from `node1` to `node2`.
  */
 private predicate localFlowStep(Node node1, Node node2, Configuration config) {
-  localFlowStep(node1, node2) and
+  simpleLocalFlowStep(node1, node2) and
   not outBarrier(node1, config) and
   not inBarrier(node2, config) and
   not fullBarrier(node1, config) and
diff --git a/cpp/ql/src/semmle/code/cpp/ir/dataflow/internal/DataFlowImpl4.qll b/cpp/ql/src/semmle/code/cpp/ir/dataflow/internal/DataFlowImpl4.qll
index f797b3bcf35b..64edab03d692 100644
--- a/cpp/ql/src/semmle/code/cpp/ir/dataflow/internal/DataFlowImpl4.qll
+++ b/cpp/ql/src/semmle/code/cpp/ir/dataflow/internal/DataFlowImpl4.qll
@@ -162,7 +162,7 @@ private predicate isAdditionalFlowStep(
  * Holds if data can flow in one local step from `node1` to `node2`.
  */
 private predicate localFlowStep(Node node1, Node node2, Configuration config) {
-  localFlowStep(node1, node2) and
+  simpleLocalFlowStep(node1, node2) and
   not outBarrier(node1, config) and
   not inBarrier(node2, config) and
   not fullBarrier(node1, config) and
diff --git a/cpp/ql/src/semmle/code/cpp/ir/dataflow/internal/DataFlowUtil.qll b/cpp/ql/src/semmle/code/cpp/ir/dataflow/internal/DataFlowUtil.qll
index 5ceb4e79682f..e9715925432a 100644
--- a/cpp/ql/src/semmle/code/cpp/ir/dataflow/internal/DataFlowUtil.qll
+++ b/cpp/ql/src/semmle/code/cpp/ir/dataflow/internal/DataFlowUtil.qll
@@ -156,6 +156,16 @@ UninitializedNode uninitializedNode(LocalVariable v) { result.getLocalVariable()
  * (intra-procedural) step.
  */
 predicate localFlowStep(Node nodeFrom, Node nodeTo) {
+  simpleLocalFlowStep(nodeFrom, nodeTo)
+}
+
+/**
+ * INTERNAL: do not use.
+ *
+ * This is the local flow predicate that's used as a building block in global
+ * data flow. It may have less flow than the `localFlowStep` predicate.
+ */
+predicate simpleLocalFlowStep(Node nodeFrom, Node nodeTo) {
   nodeTo.(CopyInstruction).getSourceValue() = nodeFrom or
   nodeTo.(PhiInstruction).getAnOperand().getDef() = nodeFrom or
   // Treat all conversions as flow, even conversions between different numeric types.
diff --git a/csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowImpl.qll b/csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowImpl.qll
index f797b3bcf35b..64edab03d692 100644
--- a/csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowImpl.qll
+++ b/csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowImpl.qll
@@ -162,7 +162,7 @@ private predicate isAdditionalFlowStep(
  * Holds if data can flow in one local step from `node1` to `node2`.
  */
 private predicate localFlowStep(Node node1, Node node2, Configuration config) {
-  localFlowStep(node1, node2) and
+  simpleLocalFlowStep(node1, node2) and
   not outBarrier(node1, config) and
   not inBarrier(node2, config) and
   not fullBarrier(node1, config) and
diff --git a/csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowImpl2.qll b/csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowImpl2.qll
index f797b3bcf35b..64edab03d692 100644
--- a/csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowImpl2.qll
+++ b/csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowImpl2.qll
@@ -162,7 +162,7 @@ private predicate isAdditionalFlowStep(
  * Holds if data can flow in one local step from `node1` to `node2`.
  */
 private predicate localFlowStep(Node node1, Node node2, Configuration config) {
-  localFlowStep(node1, node2) and
+  simpleLocalFlowStep(node1, node2) and
   not outBarrier(node1, config) and
   not inBarrier(node2, config) and
   not fullBarrier(node1, config) and
diff --git a/csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowImpl3.qll b/csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowImpl3.qll
index f797b3bcf35b..64edab03d692 100644
--- a/csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowImpl3.qll
+++ b/csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowImpl3.qll
@@ -162,7 +162,7 @@ private predicate isAdditionalFlowStep(
  * Holds if data can flow in one local step from `node1` to `node2`.
  */
 private predicate localFlowStep(Node node1, Node node2, Configuration config) {
-  localFlowStep(node1, node2) and
+  simpleLocalFlowStep(node1, node2) and
   not outBarrier(node1, config) and
   not inBarrier(node2, config) and
   not fullBarrier(node1, config) and
diff --git a/csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowImpl4.qll b/csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowImpl4.qll
index f797b3bcf35b..64edab03d692 100644
--- a/csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowImpl4.qll
+++ b/csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowImpl4.qll
@@ -162,7 +162,7 @@ private predicate isAdditionalFlowStep(
  * Holds if data can flow in one local step from `node1` to `node2`.
  */
 private predicate localFlowStep(Node node1, Node node2, Configuration config) {
-  localFlowStep(node1, node2) and
+  simpleLocalFlowStep(node1, node2) and
   not outBarrier(node1, config) and
   not inBarrier(node2, config) and
   not fullBarrier(node1, config) and
diff --git a/csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowImpl5.qll b/csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowImpl5.qll
index f797b3bcf35b..64edab03d692 100644
--- a/csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowImpl5.qll
+++ b/csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowImpl5.qll
@@ -162,7 +162,7 @@ private predicate isAdditionalFlowStep(
  * Holds if data can flow in one local step from `node1` to `node2`.
  */
 private predicate localFlowStep(Node node1, Node node2, Configuration config) {
-  localFlowStep(node1, node2) and
+  simpleLocalFlowStep(node1, node2) and
   not outBarrier(node1, config) and
   not inBarrier(node2, config) and
   not fullBarrier(node1, config) and
diff --git a/csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowPrivate.qll b/csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowPrivate.qll
index 7f78c580cb6f..10561b7c773e 100644
--- a/csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowPrivate.qll
+++ b/csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowPrivate.qll
@@ -255,6 +255,17 @@ private module Cached {
    */
   cached
   predicate localFlowStepImpl(Node nodeFrom, Node nodeTo) {
+    simpleLocalFlowStep(nodeFrom, nodeTo)
+  }
+
+  /**
+   * INTERNAL: do not use.
+   *
+   * This is the local flow predicate that's used as a building block in global
+   * data flow. It may have less flow than the `localFlowStep` predicate.
+   */
+  cached
+  predicate simpleLocalFlowStep(Node nodeFrom, Node nodeTo) {
     any(LocalFlow::LocalExprStepConfiguration x).hasNodePath(nodeFrom, nodeTo)
     or
     // Flow from SSA definition to first read
diff --git a/java/ql/src/semmle/code/java/dataflow/internal/DataFlowImpl.qll b/java/ql/src/semmle/code/java/dataflow/internal/DataFlowImpl.qll
index f797b3bcf35b..64edab03d692 100644
--- a/java/ql/src/semmle/code/java/dataflow/internal/DataFlowImpl.qll
+++ b/java/ql/src/semmle/code/java/dataflow/internal/DataFlowImpl.qll
@@ -162,7 +162,7 @@ private predicate isAdditionalFlowStep(
  * Holds if data can flow in one local step from `node1` to `node2`.
  */
 private predicate localFlowStep(Node node1, Node node2, Configuration config) {
-  localFlowStep(node1, node2) and
+  simpleLocalFlowStep(node1, node2) and
   not outBarrier(node1, config) and
   not inBarrier(node2, config) and
   not fullBarrier(node1, config) and
diff --git a/java/ql/src/semmle/code/java/dataflow/internal/DataFlowImpl2.qll b/java/ql/src/semmle/code/java/dataflow/internal/DataFlowImpl2.qll
index f797b3bcf35b..64edab03d692 100644
--- a/java/ql/src/semmle/code/java/dataflow/internal/DataFlowImpl2.qll
+++ b/java/ql/src/semmle/code/java/dataflow/internal/DataFlowImpl2.qll
@@ -162,7 +162,7 @@ private predicate isAdditionalFlowStep(
  * Holds if data can flow in one local step from `node1` to `node2`.
  */
 private predicate localFlowStep(Node node1, Node node2, Configuration config) {
-  localFlowStep(node1, node2) and
+  simpleLocalFlowStep(node1, node2) and
   not outBarrier(node1, config) and
   not inBarrier(node2, config) and
   not fullBarrier(node1, config) and
diff --git a/java/ql/src/semmle/code/java/dataflow/internal/DataFlowImpl3.qll b/java/ql/src/semmle/code/java/dataflow/internal/DataFlowImpl3.qll
index f797b3bcf35b..64edab03d692 100644
--- a/java/ql/src/semmle/code/java/dataflow/internal/DataFlowImpl3.qll
+++ b/java/ql/src/semmle/code/java/dataflow/internal/DataFlowImpl3.qll
@@ -162,7 +162,7 @@ private predicate isAdditionalFlowStep(
  * Holds if data can flow in one local step from `node1` to `node2`.
  */
 private predicate localFlowStep(Node node1, Node node2, Configuration config) {
-  localFlowStep(node1, node2) and
+  simpleLocalFlowStep(node1, node2) and
   not outBarrier(node1, config) and
   not inBarrier(node2, config) and
   not fullBarrier(node1, config) and
diff --git a/java/ql/src/semmle/code/java/dataflow/internal/DataFlowImpl4.qll b/java/ql/src/semmle/code/java/dataflow/internal/DataFlowImpl4.qll
index f797b3bcf35b..64edab03d692 100644
--- a/java/ql/src/semmle/code/java/dataflow/internal/DataFlowImpl4.qll
+++ b/java/ql/src/semmle/code/java/dataflow/internal/DataFlowImpl4.qll
@@ -162,7 +162,7 @@ private predicate isAdditionalFlowStep(
  * Holds if data can flow in one local step from `node1` to `node2`.
  */
 private predicate localFlowStep(Node node1, Node node2, Configuration config) {
-  localFlowStep(node1, node2) and
+  simpleLocalFlowStep(node1, node2) and
   not outBarrier(node1, config) and
   not inBarrier(node2, config) and
   not fullBarrier(node1, config) and
diff --git a/java/ql/src/semmle/code/java/dataflow/internal/DataFlowImpl5.qll b/java/ql/src/semmle/code/java/dataflow/internal/DataFlowImpl5.qll
index f797b3bcf35b..64edab03d692 100644
--- a/java/ql/src/semmle/code/java/dataflow/internal/DataFlowImpl5.qll
+++ b/java/ql/src/semmle/code/java/dataflow/internal/DataFlowImpl5.qll
@@ -162,7 +162,7 @@ private predicate isAdditionalFlowStep(
  * Holds if data can flow in one local step from `node1` to `node2`.
  */
 private predicate localFlowStep(Node node1, Node node2, Configuration config) {
-  localFlowStep(node1, node2) and
+  simpleLocalFlowStep(node1, node2) and
   not outBarrier(node1, config) and
   not inBarrier(node2, config) and
   not fullBarrier(node1, config) and
diff --git a/java/ql/src/semmle/code/java/dataflow/internal/DataFlowUtil.qll b/java/ql/src/semmle/code/java/dataflow/internal/DataFlowUtil.qll
index 98e4fd214c71..be8e8dc32f94 100644
--- a/java/ql/src/semmle/code/java/dataflow/internal/DataFlowUtil.qll
+++ b/java/ql/src/semmle/code/java/dataflow/internal/DataFlowUtil.qll
@@ -352,6 +352,17 @@ predicate hasNonlocalValue(FieldRead fr) {
  */
 cached
 predicate localFlowStep(Node node1, Node node2) {
+  simpleLocalFlowStep(node1, node2)
+}
+
+/**
+ * INTERNAL: do not use.
+ *
+ * This is the local flow predicate that's used as a building block in global
+ * data flow. It may have less flow than the `localFlowStep` predicate.
+ */
+cached
+predicate simpleLocalFlowStep(Node node1, Node node2) {
   // Variable flow steps through adjacent def-use and use-use pairs.
   exists(SsaExplicitUpdate upd |
     upd.getDefiningExpr().(VariableAssign).getSource() = node1.asExpr() or

From c9ea5ad9a345ca027d8c4f80f894cc2eb16df6ac Mon Sep 17 00:00:00 2001
From: Jonas Jensen <jonas@semmle.com>
Date: Wed, 21 Aug 2019 09:43:13 +0200
Subject: [PATCH 2/4] C#/Java: Remove `cached` from wrapper predicate

---
 .../dataflow/internal/DataFlowPrivate.qll       | 17 ++++++++---------
 .../java/dataflow/internal/DataFlowUtil.qll     |  1 -
 2 files changed, 8 insertions(+), 10 deletions(-)

diff --git a/csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowPrivate.qll b/csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowPrivate.qll
index 10561b7c773e..b216795bd879 100644
--- a/csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowPrivate.qll
+++ b/csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowPrivate.qll
@@ -220,6 +220,14 @@ module LocalFlow {
   }
 }
 
+/**
+ * Holds if data flows from `nodeFrom` to `nodeTo` in exactly one local
+ * (intra-procedural) step.
+ */
+predicate localFlowStepImpl(Node nodeFrom, Node nodeTo) {
+  simpleLocalFlowStep(nodeFrom, nodeTo)
+}
+
 /** A collection of cached types and predicates to be evaluated in the same stage. */
 cached
 private module Cached {
@@ -249,15 +257,6 @@ private module Cached {
     } or
     TMallocNode(ControlFlow::Nodes::ElementNode cfn) { cfn.getElement() instanceof ObjectCreation }
 
-  /**
-   * Holds if data flows from `nodeFrom` to `nodeTo` in exactly one local
-   * (intra-procedural) step.
-   */
-  cached
-  predicate localFlowStepImpl(Node nodeFrom, Node nodeTo) {
-    simpleLocalFlowStep(nodeFrom, nodeTo)
-  }
-
   /**
    * INTERNAL: do not use.
    *
diff --git a/java/ql/src/semmle/code/java/dataflow/internal/DataFlowUtil.qll b/java/ql/src/semmle/code/java/dataflow/internal/DataFlowUtil.qll
index be8e8dc32f94..6303f3660730 100644
--- a/java/ql/src/semmle/code/java/dataflow/internal/DataFlowUtil.qll
+++ b/java/ql/src/semmle/code/java/dataflow/internal/DataFlowUtil.qll
@@ -350,7 +350,6 @@ predicate hasNonlocalValue(FieldRead fr) {
 /**
  * Holds if data can flow from `node1` to `node2` in one local step.
  */
-cached
 predicate localFlowStep(Node node1, Node node2) {
   simpleLocalFlowStep(node1, node2)
 }

From ec2cc5a80e4432cf7f7ab10b1d47ad579ba16d13 Mon Sep 17 00:00:00 2001
From: Jonas Jensen <jonas@semmle.com>
Date: Wed, 21 Aug 2019 10:05:54 +0200
Subject: [PATCH 3/4] C#: Refactor how simpleLocalFlowStep is called

`localFlowStep` is no longer an alias because it should not have the
same QLDoc as `simpleLocalFlowStep`.
---
 .../code/csharp/dataflow/internal/DataFlowPrivate.qll  | 10 ----------
 .../code/csharp/dataflow/internal/DataFlowPublic.qll   |  6 +++++-
 2 files changed, 5 insertions(+), 11 deletions(-)

diff --git a/csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowPrivate.qll b/csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowPrivate.qll
index b216795bd879..15c7b055d97b 100644
--- a/csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowPrivate.qll
+++ b/csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowPrivate.qll
@@ -220,14 +220,6 @@ module LocalFlow {
   }
 }
 
-/**
- * Holds if data flows from `nodeFrom` to `nodeTo` in exactly one local
- * (intra-procedural) step.
- */
-predicate localFlowStepImpl(Node nodeFrom, Node nodeTo) {
-  simpleLocalFlowStep(nodeFrom, nodeTo)
-}
-
 /** A collection of cached types and predicates to be evaluated in the same stage. */
 cached
 private module Cached {
@@ -258,8 +250,6 @@ private module Cached {
     TMallocNode(ControlFlow::Nodes::ElementNode cfn) { cfn.getElement() instanceof ObjectCreation }
 
   /**
-   * INTERNAL: do not use.
-   *
    * This is the local flow predicate that's used as a building block in global
    * data flow. It may have less flow than the `localFlowStep` predicate.
    */
diff --git a/csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowPublic.qll b/csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowPublic.qll
index dafb7a0c0300..559fc79026bb 100644
--- a/csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowPublic.qll
+++ b/csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowPublic.qll
@@ -147,7 +147,11 @@ ExprNode exprNode(DotNet::Expr e) { result.getExpr() = e }
  */
 ParameterNode parameterNode(DotNet::Parameter p) { result.getParameter() = p }
 
-predicate localFlowStep = localFlowStepImpl/2;
+/**
+ * Holds if data flows from `nodeFrom` to `nodeTo` in exactly one local
+ * (intra-procedural) step.
+ */
+predicate localFlowStep(Node nodeFrom, Node nodeTo) { simpleLocalFlowStep(nodeFrom, nodeTo) }
 
 /**
  * Holds if data flows from `source` to `sink` in zero or more local

From 6fc3a62edbbee40c9623f2367c8a9c04ab80bf80 Mon Sep 17 00:00:00 2001
From: Jonas Jensen <jonas@semmle.com>
Date: Wed, 21 Aug 2019 10:20:15 +0200
Subject: [PATCH 4/4] C++/C#/Java: Change another caller of localFlow

There was also a use of `localFlowStep` in `DataFlowImplCommon` that
should now be `simpleLocalFlowStep`.
---
 .../code/cpp/dataflow/internal/DataFlowImplCommon.qll       | 6 +++---
 .../code/cpp/ir/dataflow/internal/DataFlowImplCommon.qll    | 6 +++---
 .../code/csharp/dataflow/internal/DataFlowImplCommon.qll    | 6 +++---
 .../code/java/dataflow/internal/DataFlowImplCommon.qll      | 6 +++---
 4 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/cpp/ql/src/semmle/code/cpp/dataflow/internal/DataFlowImplCommon.qll b/cpp/ql/src/semmle/code/cpp/dataflow/internal/DataFlowImplCommon.qll
index 94623af2a6ac..9bb6a70c7425 100644
--- a/cpp/ql/src/semmle/code/cpp/dataflow/internal/DataFlowImplCommon.qll
+++ b/cpp/ql/src/semmle/code/cpp/dataflow/internal/DataFlowImplCommon.qll
@@ -35,7 +35,7 @@ private module ImplCommon {
     or
     exists(Node mid |
       parameterValueFlowNoCtx(p, mid) and
-      localFlowStep(mid, node) and
+      simpleLocalFlowStep(mid, node) and
       compatibleTypes(p.getType(), node.getType())
     )
     or
@@ -152,7 +152,7 @@ private module ImplCommon {
     or
     exists(Node mid |
       parameterValueFlow(p, mid, cc) and
-      localFlowStep(mid, node) and
+      simpleLocalFlowStep(mid, node) and
       compatibleTypes(p.getType(), node.getType())
     )
     or
@@ -209,7 +209,7 @@ private module ImplCommon {
    * through a value-preserving method.
    */
   private predicate localValueStep(Node node1, Node node2) {
-    localFlowStep(node1, node2) or
+    simpleLocalFlowStep(node1, node2) or
     argumentValueFlowsThrough(node1, node2, _)
   }
 
diff --git a/cpp/ql/src/semmle/code/cpp/ir/dataflow/internal/DataFlowImplCommon.qll b/cpp/ql/src/semmle/code/cpp/ir/dataflow/internal/DataFlowImplCommon.qll
index 94623af2a6ac..9bb6a70c7425 100644
--- a/cpp/ql/src/semmle/code/cpp/ir/dataflow/internal/DataFlowImplCommon.qll
+++ b/cpp/ql/src/semmle/code/cpp/ir/dataflow/internal/DataFlowImplCommon.qll
@@ -35,7 +35,7 @@ private module ImplCommon {
     or
     exists(Node mid |
       parameterValueFlowNoCtx(p, mid) and
-      localFlowStep(mid, node) and
+      simpleLocalFlowStep(mid, node) and
       compatibleTypes(p.getType(), node.getType())
     )
     or
@@ -152,7 +152,7 @@ private module ImplCommon {
     or
     exists(Node mid |
       parameterValueFlow(p, mid, cc) and
-      localFlowStep(mid, node) and
+      simpleLocalFlowStep(mid, node) and
       compatibleTypes(p.getType(), node.getType())
     )
     or
@@ -209,7 +209,7 @@ private module ImplCommon {
    * through a value-preserving method.
    */
   private predicate localValueStep(Node node1, Node node2) {
-    localFlowStep(node1, node2) or
+    simpleLocalFlowStep(node1, node2) or
     argumentValueFlowsThrough(node1, node2, _)
   }
 
diff --git a/csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowImplCommon.qll b/csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowImplCommon.qll
index 94623af2a6ac..9bb6a70c7425 100644
--- a/csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowImplCommon.qll
+++ b/csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowImplCommon.qll
@@ -35,7 +35,7 @@ private module ImplCommon {
     or
     exists(Node mid |
       parameterValueFlowNoCtx(p, mid) and
-      localFlowStep(mid, node) and
+      simpleLocalFlowStep(mid, node) and
       compatibleTypes(p.getType(), node.getType())
     )
     or
@@ -152,7 +152,7 @@ private module ImplCommon {
     or
     exists(Node mid |
       parameterValueFlow(p, mid, cc) and
-      localFlowStep(mid, node) and
+      simpleLocalFlowStep(mid, node) and
       compatibleTypes(p.getType(), node.getType())
     )
     or
@@ -209,7 +209,7 @@ private module ImplCommon {
    * through a value-preserving method.
    */
   private predicate localValueStep(Node node1, Node node2) {
-    localFlowStep(node1, node2) or
+    simpleLocalFlowStep(node1, node2) or
     argumentValueFlowsThrough(node1, node2, _)
   }
 
diff --git a/java/ql/src/semmle/code/java/dataflow/internal/DataFlowImplCommon.qll b/java/ql/src/semmle/code/java/dataflow/internal/DataFlowImplCommon.qll
index 94623af2a6ac..9bb6a70c7425 100644
--- a/java/ql/src/semmle/code/java/dataflow/internal/DataFlowImplCommon.qll
+++ b/java/ql/src/semmle/code/java/dataflow/internal/DataFlowImplCommon.qll
@@ -35,7 +35,7 @@ private module ImplCommon {
     or
     exists(Node mid |
       parameterValueFlowNoCtx(p, mid) and
-      localFlowStep(mid, node) and
+      simpleLocalFlowStep(mid, node) and
       compatibleTypes(p.getType(), node.getType())
     )
     or
@@ -152,7 +152,7 @@ private module ImplCommon {
     or
     exists(Node mid |
       parameterValueFlow(p, mid, cc) and
-      localFlowStep(mid, node) and
+      simpleLocalFlowStep(mid, node) and
       compatibleTypes(p.getType(), node.getType())
     )
     or
@@ -209,7 +209,7 @@ private module ImplCommon {
    * through a value-preserving method.
    */
   private predicate localValueStep(Node node1, Node node2) {
-    localFlowStep(node1, node2) or
+    simpleLocalFlowStep(node1, node2) or
     argumentValueFlowsThrough(node1, node2, _)
   }