DerefChain

Author: hvitved

rust/ql/lib/codeql/rust/internal/TypeInference.qll

@@ -7,6 +7,7 @@ private import PathResolution
 private import Type
 private import Type as T
 private import TypeMention
+private import typeinference.DerefChain
 private import typeinference.FunctionType
 private import typeinference.FunctionOverloading as FunctionOverloading
 private import typeinference.BlanketImplementation as BlanketImplementation
@@ -1553,13 +1554,13 @@ private module MethodResolution {
      * Same as `getACandidateReceiverTypeAt`, but without borrows.
      */
     pragma[nomagic]
-    Type getACandidateReceiverTypeAtNoBorrow(string derefChain, TypePath path) {
+    Type getACandidateReceiverTypeAtNoBorrow(DerefChain derefChain, TypePath path) {
       result = this.getReceiverTypeAt(path) and
       derefChain = ""
       or
-      exists(ImplicitDeref::DerefImplItemNode impl, string derefChain0 |
-        result = ImplicitDeref::getDereferencedCandidateReceiverType(this, impl, derefChain0, path) and
-        derefChain = derefChain0 + "." + impl.getId()
+      exists(DerefImplItemNode impl, DerefChain suffix |
+        result = ImplicitDeref::getDereferencedCandidateReceiverType(this, impl, suffix, path) and
+        derefChain = DerefChain::cons(impl, suffix)
       )
     }
 
@@ -1573,7 +1574,7 @@ private module MethodResolution {
      */
     pragma[nomagic]
     private predicate hasIncompatibleTarget(
-      ImplOrTraitItemNode i, string derefChain, BorrowKind borrow, Type root
+      ImplOrTraitItemNode i, DerefChain derefChain, BorrowKind borrow, Type root
     ) {
       exists(TypePath path |
         ReceiverIsInstantiationOfSelfParam::argIsNotInstantiationOf(MkMethodCallCand(this,
@@ -1590,7 +1591,7 @@ private module MethodResolution {
      */
     pragma[nomagic]
     private predicate hasIncompatibleBlanketLikeTarget(
-      ImplItemNode impl, string derefChain, BorrowKind borrow
+      ImplItemNode impl, DerefChain derefChain, BorrowKind borrow
     ) {
       ReceiverIsNotInstantiationOfBlanketLikeSelfParam::argIsNotInstantiationOf(MkMethodCallCand(this,
           derefChain, borrow), impl, _, _)
@@ -1603,23 +1604,25 @@ private module MethodResolution {
      * Same as `getACandidateReceiverTypeAt`, but excludes pseudo types `!` and `unknown`.
      */
     pragma[nomagic]
-    Type getANonPseudoCandidateReceiverTypeAt(string derefChain, BorrowKind borrow, TypePath path) {
+    Type getANonPseudoCandidateReceiverTypeAt(
+      DerefChain derefChain, BorrowKind borrow, TypePath path
+    ) {
       result = this.getACandidateReceiverTypeAt(derefChain, borrow, path) and
       result != TNeverType() and
       result != TUnknownType()
     }
 
     pragma[nomagic]
     private Type getComplexStrippedType(
-      string derefChain, BorrowKind borrow, TypePath strippedTypePath
+      DerefChain derefChain, BorrowKind borrow, TypePath strippedTypePath
     ) {
       result = this.getANonPseudoCandidateReceiverTypeAt(derefChain, borrow, strippedTypePath) and
       isComplexRootStripped(strippedTypePath, result)
     }
 
     bindingset[derefChain, borrow, strippedTypePath, strippedType]
     private predicate hasNoCompatibleNonBlanketLikeTargetCheck(
-      string derefChain, BorrowKind borrow, TypePath strippedTypePath, Type strippedType
+      DerefChain derefChain, BorrowKind borrow, TypePath strippedTypePath, Type strippedType
     ) {
       forall(ImplOrTraitItemNode i |
         methodCallNonBlanketCandidate(this, _, i, _, strippedTypePath, strippedType)
@@ -1630,7 +1633,7 @@ private module MethodResolution {
 
     bindingset[derefChain, borrow, strippedTypePath, strippedType]
     private predicate hasNoCompatibleTargetCheck(
-      string derefChain, BorrowKind borrow, TypePath strippedTypePath, Type strippedType
+      DerefChain derefChain, BorrowKind borrow, TypePath strippedTypePath, Type strippedType
     ) {
       this.hasNoCompatibleNonBlanketLikeTargetCheck(derefChain, borrow, strippedTypePath,
         strippedType) and
@@ -1641,7 +1644,7 @@ private module MethodResolution {
 
     bindingset[derefChain, borrow, strippedTypePath, strippedType]
     private predicate hasNoCompatibleNonBlanketTargetCheck(
-      string derefChain, BorrowKind borrow, TypePath strippedTypePath, Type strippedType
+      DerefChain derefChain, BorrowKind borrow, TypePath strippedTypePath, Type strippedType
     ) {
       this.hasNoCompatibleNonBlanketLikeTargetCheck(derefChain, borrow, strippedTypePath,
         strippedType) and
@@ -1655,7 +1658,7 @@ private module MethodResolution {
     // forex using recursion
     pragma[nomagic]
     private predicate hasNoCompatibleTargetNoBorrowToIndex(
-      string derefChain, TypePath strippedTypePath, Type strippedType, int n
+      DerefChain derefChain, TypePath strippedTypePath, Type strippedType, int n
     ) {
       (
         this.supportsAutoDerefAndBorrow()
@@ -1678,7 +1681,7 @@ private module MethodResolution {
      * have a matching method target.
      */
     pragma[nomagic]
-    predicate hasNoCompatibleTargetNoBorrow(string derefChain) {
+    predicate hasNoCompatibleTargetNoBorrow(DerefChain derefChain) {
       exists(Type strippedType |
         this.hasNoCompatibleTargetNoBorrowToIndex(derefChain, _, strippedType,
           getLastLookupTypeIndex(strippedType))
@@ -1688,7 +1691,7 @@ private module MethodResolution {
     // forex using recursion
     pragma[nomagic]
     private predicate hasNoCompatibleNonBlanketTargetNoBorrowToIndex(
-      string derefChain, TypePath strippedTypePath, Type strippedType, int n
+      DerefChain derefChain, TypePath strippedTypePath, Type strippedType, int n
     ) {
       (
         this.supportsAutoDerefAndBorrow()
@@ -1712,7 +1715,7 @@ private module MethodResolution {
      * a matching non-blanket method target.
      */
     pragma[nomagic]
-    predicate hasNoCompatibleNonBlanketTargetNoBorrow(string derefChain) {
+    predicate hasNoCompatibleNonBlanketTargetNoBorrow(DerefChain derefChain) {
       exists(Type strippedType |
         this.hasNoCompatibleNonBlanketTargetNoBorrowToIndex(derefChain, _, strippedType,
           getLastLookupTypeIndex(strippedType))
@@ -1722,7 +1725,7 @@ private module MethodResolution {
     // forex using recursion
     pragma[nomagic]
     private predicate hasNoCompatibleTargetSharedBorrowToIndex(
-      string derefChain, TypePath strippedTypePath, Type strippedType, int n
+      DerefChain derefChain, TypePath strippedTypePath, Type strippedType, int n
     ) {
       this.hasNoCompatibleTargetNoBorrow(derefChain) and
       strippedType = this.getComplexStrippedType(derefChain, TSharedBorrowKind(), strippedTypePath) and
@@ -1741,7 +1744,7 @@ private module MethodResolution {
      * by a shared borrow, does not have a matching method target.
      */
     pragma[nomagic]
-    predicate hasNoCompatibleTargetSharedBorrow(string derefChain) {
+    predicate hasNoCompatibleTargetSharedBorrow(DerefChain derefChain) {
       exists(Type strippedType |
         this.hasNoCompatibleTargetSharedBorrowToIndex(derefChain, _, strippedType,
           getLastLookupTypeIndex(strippedType))
@@ -1751,7 +1754,7 @@ private module MethodResolution {
     // forex using recursion
     pragma[nomagic]
     private predicate hasNoCompatibleTargetMutBorrowToIndex(
-      string derefChain, TypePath strippedTypePath, Type strippedType, int n
+      DerefChain derefChain, TypePath strippedTypePath, Type strippedType, int n
     ) {
       this.hasNoCompatibleTargetSharedBorrow(derefChain) and
       strippedType = this.getComplexStrippedType(derefChain, TMutBorrowKind(), strippedTypePath) and
@@ -1769,7 +1772,7 @@ private module MethodResolution {
      * by a `mut` borrow, does not have a matching method target.
      */
     pragma[nomagic]
-    predicate hasNoCompatibleTargetMutBorrow(string derefChain) {
+    predicate hasNoCompatibleTargetMutBorrow(DerefChain derefChain) {
       exists(Type strippedType |
         this.hasNoCompatibleTargetMutBorrowToIndex(derefChain, _, strippedType,
           getLastLookupTypeIndex(strippedType))
@@ -1779,7 +1782,7 @@ private module MethodResolution {
     // forex using recursion
     pragma[nomagic]
     private predicate hasNoCompatibleNonBlanketTargetSharedBorrowToIndex(
-      string derefChain, TypePath strippedTypePath, Type strippedType, int n
+      DerefChain derefChain, TypePath strippedTypePath, Type strippedType, int n
     ) {
       this.hasNoCompatibleTargetNoBorrow(derefChain) and
       strippedType = this.getComplexStrippedType(derefChain, TSharedBorrowKind(), strippedTypePath) and
@@ -1798,7 +1801,7 @@ private module MethodResolution {
      * by a shared borrow, does not have a matching non-blanket method target.
      */
     pragma[nomagic]
-    predicate hasNoCompatibleNonBlanketTargetSharedBorrow(string derefChain) {
+    predicate hasNoCompatibleNonBlanketTargetSharedBorrow(DerefChain derefChain) {
       exists(Type strippedType |
         this.hasNoCompatibleNonBlanketTargetSharedBorrowToIndex(derefChain, _, strippedType,
           getLastLookupTypeIndex(strippedType))
@@ -1808,7 +1811,7 @@ private module MethodResolution {
     // forex using recursion
     pragma[nomagic]
     private predicate hasNoCompatibleNonBlanketTargetMutBorrowToIndex(
-      string derefChain, TypePath strippedTypePath, Type strippedType, int n
+      DerefChain derefChain, TypePath strippedTypePath, Type strippedType, int n
     ) {
       this.hasNoCompatibleNonBlanketTargetSharedBorrow(derefChain) and
       strippedType = this.getComplexStrippedType(derefChain, TMutBorrowKind(), strippedTypePath) and
@@ -1826,7 +1829,7 @@ private module MethodResolution {
      * by a `mut` borrow, does not have a matching non-blanket method target.
      */
     pragma[nomagic]
-    predicate hasNoCompatibleNonBlanketTargetMutBorrow(string derefChain) {
+    predicate hasNoCompatibleNonBlanketTargetMutBorrow(DerefChain derefChain) {
       exists(Type strippedType |
         this.hasNoCompatibleNonBlanketTargetMutBorrowToIndex(derefChain, _, strippedType,
           getLastLookupTypeIndex(strippedType))
@@ -1846,7 +1849,7 @@ private module MethodResolution {
      * [1]: https://doc.rust-lang.org/reference/expressions/method-call-expr.html#r-expr.method.candidate-receivers
      */
     pragma[nomagic]
-    Type getACandidateReceiverTypeAt(string derefChain, BorrowKind borrow, TypePath path) {
+    Type getACandidateReceiverTypeAt(DerefChain derefChain, BorrowKind borrow, TypePath path) {
       result = this.getACandidateReceiverTypeAtNoBorrow(derefChain, path) and
       borrow = TNoBorrowKind()
       or
@@ -1879,23 +1882,23 @@ private module MethodResolution {
      * `derefChain` and the enum `borrow`.
      */
     pragma[nomagic]
-    Method resolveCallTarget(ImplOrTraitItemNode i, string derefChain, BorrowKind borrow) {
+    Method resolveCallTarget(ImplOrTraitItemNode i, DerefChain derefChain, BorrowKind borrow) {
       exists(MethodCallCand mcc |
         mcc = MkMethodCallCand(this, derefChain, borrow) and
         result = mcc.resolveCallTarget(i)
       )
     }
 
     predicate receiverHasImplicitDeref(AstNode receiver) {
-      exists(ImplicitDeref::DerefImplItemNode impl |
+      exists(DerefImplItemNode impl |
         impl.isRefImpl() and
-        exists(this.resolveCallTarget(_, "." + impl.getId(), TNoBorrowKind())) and
+        exists(this.resolveCallTarget(_, DerefChain::singleton(impl), TNoBorrowKind())) and
         receiver = this.getArg(any(ArgumentPosition pos | pos.isSelf()))
       )
     }
 
     predicate argumentHasImplicitBorrow(AstNode arg, BorrowKind borrow) {
-      exists(this.resolveCallTarget(_, "", borrow)) and
+      exists(this.resolveCallTarget(_, DerefChain::nil(), borrow)) and
       borrow != TNoBorrowKind() and
       arg = this.getArg(any(ArgumentPosition pos | pos.isSelf()))
     }
@@ -2056,14 +2059,14 @@ private module MethodResolution {
   }
 
   private newtype TMethodCallCand =
-    MkMethodCallCand(MethodCall mc, string derefChain, BorrowKind borrow) {
+    MkMethodCallCand(MethodCall mc, DerefChain derefChain, BorrowKind borrow) {
       exists(mc.getACandidateReceiverTypeAt(derefChain, borrow, _))
     }
 
   /** A method call with a dereference chain and a potential borrow. */
   private class MethodCallCand extends MkMethodCallCand {
     MethodCall mc_;
-    string derefChain;
+    DerefChain derefChain;
     BorrowKind borrow;
 
     MethodCallCand() { this = MkMethodCallCand(mc_, derefChain, borrow) }
@@ -2161,51 +2164,16 @@ private module MethodResolution {
   }
 
   module ImplicitDeref {
-    private import codeql.rust.elements.internal.generated.Raw
-    private import codeql.rust.elements.internal.generated.Synth
-
-    /** An `impl` block that implements the `Deref` trait. */
-    class DerefImplItemNode extends ImplItemNode {
-      DerefImplItemNode() { this.resolveTraitTy() instanceof DerefTrait }
-
-      /**
-       * Holds if this `impl` block is the special `Deref` implementation for
-       * `&T` or `&mut T`:
-       *
-       * ```rust
-       * impl<T: ?Sized> const Deref for &T
-       * ```
-       *
-       * or
-       *
-       * ```rust
-       * impl<T: ?Sized> const Deref for &mut T
-       * ```
-       */
-      predicate isRefImpl() { this.resolveSelfTyBuiltin() instanceof Builtins::RefType }
-
-      /** Gets an internal unique ID used to identify this block amongst all `Deref` impl blocks. */
-      int getId() { idOfRaw(Synth::convertAstNodeToRaw(this), result) }
-    }
-
-    private class DerefImplItemRaw extends Raw::Impl {
-      DerefImplItemRaw() { this = Synth::convertAstNodeToRaw(any(DerefImplItemNode i)) }
-    }
-
-    private predicate id(DerefImplItemRaw x, DerefImplItemRaw y) { x = y }
-
-    private predicate idOfRaw(DerefImplItemRaw x, int y) = equivalenceRelation(id/2)(x, y)
-
     private newtype TMethodCallDerefCand =
-      MkMethodCallDerefCand(MethodCall mc, string derefChain) {
+      MkMethodCallDerefCand(MethodCall mc, DerefChain derefChain) {
         mc.supportsAutoDerefAndBorrow() and
         mc.hasNoCompatibleTargetMutBorrow(derefChain) and
         exists(mc.getACandidateReceiverTypeAtNoBorrow(derefChain, _))
       }
 
     private class MethodCallDerefCand extends MkMethodCallDerefCand {
       MethodCall mc_;
-      string derefChain;
+      DerefChain derefChain;
 
       MethodCallDerefCand() { this = MkMethodCallDerefCand(mc_, derefChain) }
 
@@ -2241,7 +2209,7 @@ private module MethodResolution {
 
     pragma[nomagic]
     Type getDereferencedCandidateReceiverType(
-      MethodCall mc, DerefImplItemNode impl, string derefChain, TypePath path
+      MethodCall mc, DerefImplItemNode impl, DerefChain derefChain, TypePath path
     ) {
       exists(MethodCallDerefCand mcc, TypePath exprPath |
         mcc = MkMethodCallDerefCand(mc, derefChain) and
@@ -2607,10 +2575,10 @@ private Type inferMethodCallType1(AstNode n, boolean isReturn, TypePath path) {
     path = path0
     or
     // adjust for implicit deref
-    exists(MethodResolution::ImplicitDeref::DerefImplItemNode impl |
+    exists(DerefImplItemNode impl |
       impl.isRefImpl() and
       apos.isSelf() and
-      derefChainBorrow = "." + impl.getId() + ";" and
+      derefChainBorrow = DerefChain::singleton(impl) + ";" and
       path = TypePath::cons(getRefTypeParameter(), path0)
     )
     or