Rust: Use nodes from CfgNodes.qll in DataFlowImpl.qll

rust/ql/lib/codeql/rust/controlflow/CfgNodes.qll

@@ -14,3 +14,127 @@ class AstCfgNode extends CfgNode {
 
   AstCfgNode() { node = this.getAstNode() }
 }
+
+/**
+ * An assignment expression, for example
+ *
+ * ```rust
+ * x = y;
+ * ```
+ */
+final class AssignmentExprCfgNode extends BinaryExprCfgNode {
+  AssignmentExpr a;
+
+  AssignmentExprCfgNode() { a = this.getBinaryExpr() }
+
+  /** Gets the underlying `AssignmentExpr`. */
+  AssignmentExpr getAssignmentExpr() { result = a }
+}
+
+/**
+ * A match expression. For example:
+ * ```rust
+ * match x {
+ *     Option::Some(y) => y,
+ *     Option::None => 0,
+ * }
+ * ```
+ * ```rust
+ * match x {
+ *     Some(y) if y != 0 => 1 / y,
+ *     _ => 0,
+ * }
+ * ```
+ */
+final class MatchExprCfgNode extends Nodes::MatchExprCfgNode {
+  private MatchExpr node;
+
+  MatchExprCfgNode() { node = this.getMatchExpr() }
+
+  /**
+   * Gets the pattern of the `i`th match arm, if it exists.
+   */
+  PatCfgNode getArmPat(int i) {
+    any(ChildMapping mapping).hasCfgChild(node, node.getArm(i).getPat(), this, result)
+  }
+
+  /**
+   * Gets the guard of the `i`th match arm, if it exists.
+   */
+  ExprCfgNode getArmGuard(int i) {
+    any(ChildMapping mapping)
+        .hasCfgChild(node, node.getArm(i).getGuard().getCondition(), this, result)
+  }
+
+  /**
+   * Gets the expression of the `i`th match arm, if it exists.
+   */
+  ExprCfgNode getArmExpr(int i) {
+    any(ChildMapping mapping).hasCfgChild(node, node.getArm(i).getExpr(), this, result)
+  }
+}
+
+/**
+ * A block expression. For example:
+ * ```rust
+ * {
+ *     let x = 42;
+ * }
+ * ```
+ * ```rust
+ * 'label: {
+ *     let x = 42;
+ *     x
+ * }
+ * ```
+ */
+final class BlockExprCfgNode extends Nodes::BlockExprCfgNode {
+  private BlockExprChildMapping node;
+
+  BlockExprCfgNode() { node = this.getAstNode() }
+
+  /**
+   * Gets the tail expression of this block, if it exists.
+   */
+  ExprCfgNode getTailExpr() {
+    any(ChildMapping mapping).hasCfgChild(node, node.getStmtList().getTailExpr(), this, result)
+  }
+}
+
+/**
+ * A break expression. For example:
+ * ```rust
+ * loop {
+ *     if not_ready() {
+ *         break;
+ *      }
+ * }
+ * ```
+ * ```rust
+ * let x = 'label: loop {
+ *     if done() {
+ *         break 'label 42;
+ *     }
+ * };
+ * ```
+ * ```rust
+ * let x = 'label: {
+ *     if exit() {
+ *         break 'label 42;
+ *     }
+ *     0;
+ * };
+ * ```
+ */
+final class BreakExprCfgNode extends Nodes::BreakExprCfgNode {
+  /**
+   * Gets the target of this `break` expression.
+   *
+   * The target is either a `LoopExpr`, a `ForExpr`, a `WhileExpr`, or a
+   * `BlockExpr`.
+   */
+  ExprCfgNode getTarget() {
+    any(ChildMapping mapping)
+        .hasCfgChild(this.getBreakExpr().getTarget(), this.getBreakExpr(), result, this)
+  }
+}

rust/ql/lib/codeql/rust/controlflow/internal/CfgNodes.qll

@@ -43,6 +43,24 @@ private module CfgNodesInput implements InputSig<Location> {
 
 import MakeCfgNodes<Location, CfgNodesInput>
 
+class MatchExprChildMapping extends AstNodeWithChild, MatchExpr {
+  override predicate relevantChild(AstNode child) {
+    child = this.getAnArm().getPat()
+    or
+    child = this.getAnArm().getGuard().getCondition()
+    or
+    child = this.getAnArm().getExpr()
+  }
+}
+
+class BlockExprChildMapping extends AstNodeWithChild, BlockExpr {
+  override predicate relevantChild(AstNode child) { child = this.getStmtList().getTailExpr() }
+}
+
+class BreakExprTargetChildMapping extends AstNodeWithChild, Expr {
+  override predicate relevantChild(AstNode child) { child.(BreakExpr).getTarget() = this }
+}
+
 private class ChildMappingImpl extends ChildMapping {
   pragma[nomagic]
   predicate reachesBasicBlock(AstNode parent, AstNode child, CfgNode cfn, BasicBlock bb) {

rust/ql/lib/codeql/rust/dataflow/Ssa.qll

@@ -9,6 +9,7 @@ module Ssa {
   private import rust
   private import codeql.rust.controlflow.BasicBlocks
   private import codeql.rust.controlflow.ControlFlowGraph
+  private import codeql.rust.controlflow.CfgNodes
   private import codeql.rust.controlflow.internal.ControlFlowGraphImpl as CfgImpl
   private import internal.SsaImpl as SsaImpl
 
@@ -221,11 +222,11 @@ module Ssa {
      * end
      * ```
      */
-    predicate assigns(CfgNode value) {
-      exists(AssignmentExpr ae, BasicBlock bb, int i |
+    predicate assigns(ExprCfgNode value) {
+      exists(AssignmentExprCfgNode ae, BasicBlock bb, int i |
         this.definesAt(_, bb, i) and
-        ae.getLhs() = bb.getNode(i).getAstNode() and
-        value.getAstNode() = ae.getRhs()
+        ae.getLhs() = bb.getNode(i) and
+        value = ae.getRhs()
       )
     }
 

rust/ql/lib/codeql/rust/dataflow/internal/DataFlowImpl.qll

@@ -27,7 +27,7 @@ module Node {
     /**
      * Gets the expression that corresponds to this node, if any.
      */
-    Expr asExpr() { none() }
+    ExprCfgNode asExpr() { none() }
 
     /**
      * Gets the control flow node that corresponds to this data flow node.
@@ -67,11 +67,11 @@ module Node {
 
     ExprNode() { this = TExprNode(n) }
 
-    override Location getLocation() { result = n.getExpr().getLocation() }
+    override Location getLocation() { result = n.getLocation() }
 
-    override string toString() { result = n.getExpr().toString() }
+    override string toString() { result = n.toString() }
 
-    override Expr asExpr() { result = n.getExpr() }
+    override ExprCfgNode asExpr() { result = n }
 
     override CfgNode getCfgNode() { result = n }
   }
@@ -152,7 +152,7 @@ module SsaFlow {
   Impl::Node asNode(Node n) {
     n = TSsaNode(result)
     or
-    result.(Impl::ExprNode).getExpr() = n.(Node::ExprNode).getCfgNode()
+    result.(Impl::ExprNode).getExpr() = n.asExpr()
     or
     n = toParameterNode(result.(Impl::ParameterNode).getParameter())
   }
@@ -166,29 +166,18 @@ module SsaFlow {
   }
 }
 
-/**
- * Holds for expressions `e` that evaluate to the value of any last (in
- * evaluation order) subexpressions within it. E.g., expressions that propagate
- * a values from a subexpression.
- *
- * For instance, the predicate holds for if expressions as `if b { e1 } else {
- * e2 }` evalates to the value of one of the subexpressions `e1` or `e2`.
- */
-private predicate propagatesValue(Expr e) {
-  e instanceof IfExpr or
-  e instanceof LoopExpr or
-  e instanceof ReturnExpr or
-  e instanceof BreakExpr or
-  e.(BlockExpr).getStmtList().hasTailExpr() or
-  e instanceof MatchExpr
-}
-
 /**
  * Gets a node that may execute last in `n`, and which, when it executes last,
  * will be the value of `n`.
  */
-private ExprCfgNode getALastEvalNode(ExprCfgNode n) {
-  propagatesValue(n.getExpr()) and result.getASuccessor() = n
+private ExprCfgNode getALastEvalNode(ExprCfgNode e) {
+  e = any(IfExprCfgNode n | result = [n.getThen(), n.getElse()]) or
+  result = e.(LoopExprCfgNode).getLoopBody() or
+  result = e.(ReturnExprCfgNode).getExpr() or
+  result = e.(BreakExprCfgNode).getExpr() or
+  result = e.(BlockExprCfgNode).getTailExpr() or
+  result = e.(MatchExprCfgNode).getArmExpr(_) or
+  result.(BreakExprCfgNode).getTarget() = e
 }
 
 module LocalFlow {
@@ -230,10 +219,10 @@ module RustDataFlow implements InputSig<Location> {
   class DataFlowExpr = ExprCfgNode;
 
   /** Gets the node corresponding to `e`. */
-  Node exprNode(DataFlowExpr e) { result.getCfgNode() = e }
+  Node exprNode(DataFlowExpr e) { result.asExpr() = e }
 
   final class DataFlowCall extends TNormalCall {
-    private CallExpr c;
+    private CallExprCfgNode c;
 
     DataFlowCall() { this = TNormalCall(c) }
 
@@ -400,7 +389,7 @@ private module Cached {
     TSsaNode(SsaImpl::DataFlowIntegration::SsaNode node)
 
   cached
-  newtype TDataFlowCall = TNormalCall(CallExpr c)
+  newtype TDataFlowCall = TNormalCall(CallExprCfgNode c)
 
   cached
   newtype TOptionalContentSet =

rust/ql/test/query-tests/unusedentities/CONSISTENCY/DataFlowConsistency.expected

@@ -112,25 +112,20 @@ uniqueCallEnclosingCallable
 | unreachable.rs:2:5:2:18 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:6:5:6:24 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:10:5:10:20 | CallExpr | Call should have one enclosing callable but has 0. |
-| unreachable.rs:19:9:19:22 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:21:9:21:22 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:25:9:25:22 | CallExpr | Call should have one enclosing callable but has 0. |
-| unreachable.rs:27:9:27:22 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:30:13:30:26 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:33:13:33:26 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:37:8:37:13 | CallExpr | Call should have one enclosing callable but has 0. |
-| unreachable.rs:39:9:39:22 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:42:8:42:13 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:43:9:43:22 | CallExpr | Call should have one enclosing callable but has 0. |
-| unreachable.rs:46:9:46:22 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:48:5:48:18 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:50:8:50:13 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:51:17:51:22 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:54:13:54:26 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:56:17:56:30 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:58:13:58:26 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:62:8:62:13 | CallExpr | Call should have one enclosing callable but has 0. |
-| unreachable.rs:67:5:67:18 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:71:8:71:13 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:72:9:72:22 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:73:16:73:25 | CallExpr | Call should have one enclosing callable but has 0. |
@@ -157,15 +152,13 @@ uniqueCallEnclosingCallable
 | unreachable.rs:111:8:111:13 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:112:9:112:22 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:114:13:114:20 | CallExpr | Call should have one enclosing callable but has 0. |
-| unreachable.rs:114:13:114:20 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:115:9:115:22 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:116:22:116:29 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:116:22:116:29 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:117:9:117:22 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:120:8:120:13 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:121:9:121:22 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:123:13:123:20 | CallExpr | Call should have one enclosing callable but has 0. |
-| unreachable.rs:123:13:123:20 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:124:9:124:22 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:125:21:125:28 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:125:21:125:28 | CallExpr | Call should have one enclosing callable but has 0. |
@@ -174,36 +167,24 @@ uniqueCallEnclosingCallable
 | unreachable.rs:136:13:136:26 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:139:5:139:18 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:141:11:141:24 | CallExpr | Call should have one enclosing callable but has 0. |
-| unreachable.rs:149:5:149:18 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:154:9:154:22 | CallExpr | Call should have one enclosing callable but has 0. |
-| unreachable.rs:156:9:156:22 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:159:8:159:13 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:160:15:160:20 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:161:13:161:26 | CallExpr | Call should have one enclosing callable but has 0. |
-| unreachable.rs:165:13:165:26 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:169:13:169:26 | CallExpr | Call should have one enclosing callable but has 0. |
-| unreachable.rs:171:9:171:22 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:175:12:175:17 | CallExpr | Call should have one enclosing callable but has 0. |
-| unreachable.rs:177:13:177:26 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:179:9:179:22 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:183:12:183:17 | CallExpr | Call should have one enclosing callable but has 0. |
-| unreachable.rs:185:13:185:26 | CallExpr | Call should have one enclosing callable but has 0. |
-| unreachable.rs:188:5:188:18 | CallExpr | Call should have one enclosing callable but has 0. |
-| unreachable.rs:189:5:189:18 | CallExpr | Call should have one enclosing callable but has 0. |
-| unreachable.rs:190:5:190:18 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:198:22:198:41 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:199:9:199:22 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:202:9:202:22 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:205:5:205:18 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:207:16:207:29 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:209:9:209:22 | CallExpr | Call should have one enclosing callable but has 0. |
-| unreachable.rs:212:9:212:22 | CallExpr | Call should have one enclosing callable but has 0. |
-| unreachable.rs:215:5:215:18 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:219:19:219:38 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:220:9:220:22 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:224:5:224:18 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:226:13:226:32 | CallExpr | Call should have one enclosing callable but has 0. |
-| unreachable.rs:228:9:228:22 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:232:5:232:18 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:236:8:236:13 | CallExpr | Call should have one enclosing callable but has 0. |
 | unreachable.rs:237:9:237:22 | CallExpr | Call should have one enclosing callable but has 0. |