wip

Author: hvitved

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

@@ -3255,19 +3255,28 @@ private predicate inferOperationType =
   ContextTyping::CheckContextTyping<inferOperationType0/3>::check/2;
 
 pragma[nomagic]
-private Type getFieldExprLookupType(FieldExpr fe, string name, boolean isDereferenced) {
+private Type getFieldExprLookupType(FieldExpr fe, string name, DerefChain derefChain) {
   exists(TypePath path |
     result = inferType(fe.getContainer(), path) and
     name = fe.getIdentifier().getText() and
-    isComplexRootStripped(path, result) and
-    if path.isEmpty() then isDereferenced = false else isDereferenced = true
+    isComplexRootStripped(path, result)
+  |
+    // TODO: Support full derefence chains as for method calls
+    path.isEmpty() and
+    derefChain = DerefChain::nil()
+    or
+    exists(DerefImplItemNode impl, TypeParamTypeParameter tp |
+      tp.getTypeParam() = impl.resolveSelfTy().getTypeParam(0) and
+      path.getHead() = tp and
+      derefChain = DerefChain::singleton(impl)
+    )
   )
 }
 
 pragma[nomagic]
-private Type getTupleFieldExprLookupType(FieldExpr fe, int pos, boolean isDereferenced) {
+private Type getTupleFieldExprLookupType(FieldExpr fe, int pos, DerefChain derefChain) {
   exists(string name |
-    result = getFieldExprLookupType(fe, name, isDereferenced) and
+    result = getFieldExprLookupType(fe, name, derefChain) and
     pos = name.toInt()
   )
 }
@@ -3927,12 +3936,15 @@ private module Cached {
   predicate implicitDeref(AstNode n) {
     any(MethodResolution::MethodCall mc).receiverHasImplicitDeref(n)
     or
-    n =
-      any(FieldExpr fe |
-        exists(resolveStructFieldExpr(fe, true))
-        or
-        exists(resolveTupleFieldExpr(fe, true))
-      ).getContainer()
+    exists(DerefChain derefChain |
+      n =
+        any(FieldExpr fe |
+          exists(resolveStructFieldExpr(fe, derefChain))
+          or
+          exists(resolveTupleFieldExpr(fe, derefChain))
+        ).getContainer() and
+      not derefChain.isEmpty()
+    )
   }
 
   /** Holds if `n` is implicitly borrowed. */
@@ -3968,9 +3980,9 @@ private module Cached {
    * Gets the struct field that the field expression `fe` resolves to, if any.
    */
   cached
-  StructField resolveStructFieldExpr(FieldExpr fe, boolean isDereferenced) {
+  StructField resolveStructFieldExpr(FieldExpr fe, DerefChain derefChain) {
     exists(string name, Type ty |
-      ty = getFieldExprLookupType(fe, pragma[only_bind_into](name), isDereferenced)
+      ty = getFieldExprLookupType(fe, pragma[only_bind_into](name), derefChain)
     |
       result = ty.(StructType).getStruct().getStructField(pragma[only_bind_into](name)) or
       result = ty.(UnionType).getUnion().getStructField(pragma[only_bind_into](name))
@@ -3981,10 +3993,10 @@ private module Cached {
    * Gets the tuple field that the field expression `fe` resolves to, if any.
    */
   cached
-  TupleField resolveTupleFieldExpr(FieldExpr fe, boolean isDereferenced) {
+  TupleField resolveTupleFieldExpr(FieldExpr fe, DerefChain derefChain) {
     exists(int i |
       result =
-        getTupleFieldExprLookupType(fe, pragma[only_bind_into](i), isDereferenced)
+        getTupleFieldExprLookupType(fe, pragma[only_bind_into](i), derefChain)
             .(StructType)
             .getStruct()
             .getTupleField(pragma[only_bind_into](i))