Merge pull request #18754 from paldepind/rust-ref-pattern

Rust ref pattern

Author: paldepind

rust/ql/.generated.list

@@ -648,8 +648,12 @@ module PatternTrees {
 
   abstract class PostOrderPatTree extends StandardPatTree, StandardPostOrderTree { }
 
-  class IdentPatTree extends PostOrderPatTree, IdentPat {
-    override Pat getPat(int i) { i = 0 and result = this.getPat() }
+  class IdentPatTree extends PostOrderTree, IdentPat {
+    override predicate first(AstNode node) {
+      first(this.getPat(), node)
+      or
+      not this.hasPat() and node = this.getName()
+    }
 
     override predicate last(AstNode node, Completion c) {
       super.last(node, c)
@@ -658,8 +662,16 @@ module PatternTrees {
     }
 
     override predicate succ(AstNode pred, AstNode succ, Completion c) {
-      super.succ(pred, succ, c) and c.(MatchCompletion).succeeded()
+      // Edge from successful subpattern to name
+      last(this.getPat(), pred, c) and
+      first(this.getName(), succ) and
+      c.(MatchCompletion).succeeded()
+      or
+      // Edge from name to the identifier pattern itself
+      last(this.getName(), pred, c) and succ = this and completionIsNormal(c)
     }
+
+    override predicate propagatesAbnormal(AstNode child) { child = this.getPat() }
   }
 
   class BoxPatTree extends PreOrderPatTree, BoxPat {

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

@@ -195,7 +195,7 @@ module Ssa {
       )
       or
       exists(LetStmtCfgNode ls |
-        ls.getPat() = write and
+        ls.getPat().(IdentPatCfgNode).getName() = write and
         ls.getInitializer() = value
       )
     }

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

@@ -292,6 +292,15 @@ module Node {
     override PatCfgNode asPat() { result = n }
   }
 
+  /** A data flow node that corresponds to a name node in the CFG. */
+  final class NameNode extends AstCfgFlowNode, TNameNode {
+    override NameCfgNode n;
+
+    NameNode() { this = TNameNode(n) }
+
+    NameCfgNode asName() { result = n }
+  }
+
   /**
    * The value of a parameter at function entry, viewed as a node in a data
    * flow graph.
@@ -603,11 +612,23 @@ module LocalFlow {
   predicate localFlowStepCommon(Node nodeFrom, Node nodeTo) {
     nodeFrom.getCfgNode() = getALastEvalNode(nodeTo.getCfgNode())
     or
+    // An edge from the right-hand side of a let statement to the left-hand side.
     exists(LetStmtCfgNode s |
       nodeFrom.getCfgNode() = s.getInitializer() and
       nodeTo.getCfgNode() = s.getPat()
     )
     or
+    exists(IdentPatCfgNode p |
+      not p.isRef() and
+      nodeFrom.getCfgNode() = p and
+      nodeTo.getCfgNode() = p.getName()
+    )
+    or
+    exists(SelfParamCfgNode self |
+      nodeFrom.getCfgNode() = self and
+      nodeTo.getCfgNode() = self.getName()
+    )
+    or
     // An edge from a pattern/expression to its corresponding SSA definition.
     nodeFrom.(Node::AstCfgFlowNode).getCfgNode() =
       nodeTo.(Node::SsaNode).getDefinitionExt().(Ssa::WriteDefinition).getControlFlowNode()
@@ -1285,6 +1306,14 @@ module RustDataFlow implements InputSig<Location> {
         node2.asExpr().(ArrayListExprCfgNode).getAnExpr()
       ]
     or
+    // Store from a `ref` identifier pattern into the contained name.
+    exists(IdentPatCfgNode p |
+      c instanceof ReferenceContent and
+      p.isRef() and
+      node1.asPat() = p and
+      node2.(Node::NameNode).asName() = p.getName()
+    )
+    or
     fieldAssignment(node1, node2.(PostUpdateNode).getPreUpdateNode(), c)
     or
     referenceAssignment(node1, node2.(PostUpdateNode).getPreUpdateNode(), c)
@@ -1579,6 +1608,7 @@ private module Cached {
     TExprNode(ExprCfgNode n) { Stages::DataFlowStage::ref() } or
     TSourceParameterNode(ParamBaseCfgNode p) or
     TPatNode(PatCfgNode p) or
+    TNameNode(NameCfgNode n) { n.getName() = any(Variable v).getName() } or
     TExprPostUpdateNode(ExprCfgNode e) {
       isArgumentForCall(e, _, _) or
       lambdaCallExpr(_, _, e) or

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

@@ -7,25 +7,25 @@ private import Cfg
 private import codeql.rust.controlflow.internal.ControlFlowGraphImpl as ControlFlowGraphImpl
 private import codeql.ssa.Ssa as SsaImplCommon
 
-/** Holds if `v` is introduced like `let v : i64;`. */
-private predicate isUnitializedLet(IdentPat pat, Variable v) {
-  pat = v.getPat() and
+/**
+ * Holds if `name` occurs in the left-hand side of an uninitialized let
+ * statement such as in `let name : i64;`.
+ */
+private predicate isInUninitializedLet(Name name) {
   exists(LetStmt let |
-    let = v.getLetStmt() and
+    let.getPat().(IdentPat).getName() = name and
     not let.hasInitializer()
   )
 }
 
 /** Holds if `write` writes to variable `v`. */
 predicate variableWrite(AstNode write, Variable v) {
-  exists(IdentPat pat |
-    pat = write and
-    pat = v.getPat() and
-    not isUnitializedLet(pat, v)
+  exists(Name name |
+    name = write and
+    name = v.getName() and
+    not isInUninitializedLet(name)
   )
   or
-  exists(SelfParam self | self = write and self = v.getSelfParam())
-  or
   exists(VariableAccess access |
     access = write and
     access.getVariable() = v