From 9fd04e62cfe3b4a0dabccaf7a121b09c6b22ac9d Mon Sep 17 00:00:00 2001
From: Tom Hvitved <hvitved@github.com>
Date: Thu, 29 Oct 2026 10:40:19 +0100
Subject: [PATCH 1/3] Unified: Add accessor FP/FN flow test

---
 .../dataflow/accessors_instance.swift         |  9 ++++--
 .../test/library-tests/dataflow/test.expected | 28 ++++++++++++++-----
 2 files changed, 28 insertions(+), 9 deletions(-)

diff --git a/unified/ql/test/library-tests/dataflow/accessors_instance.swift b/unified/ql/test/library-tests/dataflow/accessors_instance.swift
index 4771c48dc2a6..b4bcd8125c1b 100644
--- a/unified/ql/test/library-tests/dataflow/accessors_instance.swift
+++ b/unified/ql/test/library-tests/dataflow/accessors_instance.swift
@@ -131,11 +131,16 @@ func t11() {
     class C {
         var p: (String, String) {
             get { ("safe", "safe") }
-            set { sink(newValue.0) }  // $ hasValueFlow=t11.1
+            set { sink(newValue.0) }  // $ hasValueFlow=t11.1 $ MISSING: hasValueFlow=t11.2
+        }
+        var q: C {
+            get { C() }
+            set { sink(newValue.p.0) }  // $ SPURIOUS: hasValueFlow=t11.2
         }
     }
     let c = C()
     c.p.0 = source("t11.1")
+    c.q.p = (source("t11.2"), source("t11.3"))
 }
 
 func t12() {
@@ -150,5 +155,5 @@ func t12() {
         }
     }
     let c = C()
-    c.s.update() // MISSING: the call to 'update' is not resolved
+    c.s.update()  // MISSING: the call to 'update' is not resolved
 }
diff --git a/unified/ql/test/library-tests/dataflow/test.expected b/unified/ql/test/library-tests/dataflow/test.expected
index 6d237e15124b..5b3c0d3e6065 100644
--- a/unified/ql/test/library-tests/dataflow/test.expected
+++ b/unified/ql/test/library-tests/dataflow/test.expected
@@ -32,9 +32,15 @@ edges
 | accessors_instance.swift:119:13:119:17 | field | accessors_instance.swift:125:18:125:22 | field | provenance |  |
 | accessors_instance.swift:119:21:119:35 | source(...) | accessors_instance.swift:119:13:119:17 | field | provenance |  |
 | accessors_instance.swift:134:24:134:31 | newValue [0] | accessors_instance.swift:134:24:134:33 | ... .0 | provenance |  |
-| accessors_instance.swift:138:5:138:7 | [post] ... .p [0] | accessors_instance.swift:134:24:134:31 | newValue [0] | provenance |  |
-| accessors_instance.swift:138:5:138:9 | ... .0 | accessors_instance.swift:138:5:138:7 | [post] ... .p [0] | provenance |  |
-| accessors_instance.swift:138:13:138:27 | source(...) | accessors_instance.swift:138:5:138:9 | ... .0 | provenance |  |
+| accessors_instance.swift:138:24:138:31 | newValue [p, 0] | accessors_instance.swift:138:24:138:33 | ... .p [0] | provenance |  |
+| accessors_instance.swift:138:24:138:33 | ... .p [0] | accessors_instance.swift:138:24:138:35 | ... .0 | provenance |  |
+| accessors_instance.swift:142:5:142:7 | [post] ... .p [0] | accessors_instance.swift:134:24:134:31 | newValue [0] | provenance |  |
+| accessors_instance.swift:142:5:142:9 | ... .0 | accessors_instance.swift:142:5:142:7 | [post] ... .p [0] | provenance |  |
+| accessors_instance.swift:142:13:142:27 | source(...) | accessors_instance.swift:142:5:142:9 | ... .0 | provenance |  |
+| accessors_instance.swift:143:5:143:7 | [post] ... .q [p, 0] | accessors_instance.swift:138:24:138:31 | newValue [p, 0] | provenance |  |
+| accessors_instance.swift:143:5:143:9 | ... .p [0] | accessors_instance.swift:143:5:143:7 | [post] ... .q [p, 0] | provenance |  |
+| accessors_instance.swift:143:13:143:46 | TupleExpr [0] | accessors_instance.swift:143:5:143:9 | ... .p [0] | provenance |  |
+| accessors_instance.swift:143:14:143:28 | source(...) | accessors_instance.swift:143:13:143:46 | TupleExpr [0] | provenance |  |
 | accessors_local.swift:7:21:7:34 | source(...) | accessors_local.swift:8:10:8:10 | x | provenance |  |
 | accessors_local.swift:15:15:15:28 | source(...) | accessors_local.swift:17:10:17:10 | x | provenance |  |
 | accessors_local.swift:22:15:22:28 | source(...) | accessors_local.swift:25:10:25:10 | x | provenance |  |
@@ -558,9 +564,16 @@ nodes
 | accessors_instance.swift:125:18:125:22 | field | semmle.label | field |
 | accessors_instance.swift:134:24:134:31 | newValue [0] | semmle.label | newValue [0] |
 | accessors_instance.swift:134:24:134:33 | ... .0 | semmle.label | ... .0 |
-| accessors_instance.swift:138:5:138:7 | [post] ... .p [0] | semmle.label | [post] ... .p [0] |
-| accessors_instance.swift:138:5:138:9 | ... .0 | semmle.label | ... .0 |
-| accessors_instance.swift:138:13:138:27 | source(...) | semmle.label | source(...) |
+| accessors_instance.swift:138:24:138:31 | newValue [p, 0] | semmle.label | newValue [p, 0] |
+| accessors_instance.swift:138:24:138:33 | ... .p [0] | semmle.label | ... .p [0] |
+| accessors_instance.swift:138:24:138:35 | ... .0 | semmle.label | ... .0 |
+| accessors_instance.swift:142:5:142:7 | [post] ... .p [0] | semmle.label | [post] ... .p [0] |
+| accessors_instance.swift:142:5:142:9 | ... .0 | semmle.label | ... .0 |
+| accessors_instance.swift:142:13:142:27 | source(...) | semmle.label | source(...) |
+| accessors_instance.swift:143:5:143:7 | [post] ... .q [p, 0] | semmle.label | [post] ... .q [p, 0] |
+| accessors_instance.swift:143:5:143:9 | ... .p [0] | semmle.label | ... .p [0] |
+| accessors_instance.swift:143:13:143:46 | TupleExpr [0] | semmle.label | TupleExpr [0] |
+| accessors_instance.swift:143:14:143:28 | source(...) | semmle.label | source(...) |
 | accessors_local.swift:7:21:7:34 | source(...) | semmle.label | source(...) |
 | accessors_local.swift:8:10:8:10 | x | semmle.label | x |
 | accessors_local.swift:15:15:15:28 | source(...) | semmle.label | source(...) |
@@ -1191,7 +1204,8 @@ testFailures
 | accessors_instance.swift:99:10:99:21 | ... .otherField | accessors_instance.swift:97:15:97:28 | source(...) | accessors_instance.swift:99:10:99:21 | ... .otherField | $@ | accessors_instance.swift:97:15:97:28 | source(...) | source(...) |
 | accessors_instance.swift:112:10:112:16 | ... .field | accessors_instance.swift:106:21:106:34 | source(...) | accessors_instance.swift:112:10:112:16 | ... .field | $@ | accessors_instance.swift:106:21:106:34 | source(...) | source(...) |
 | accessors_instance.swift:125:18:125:22 | field | accessors_instance.swift:119:21:119:35 | source(...) | accessors_instance.swift:125:18:125:22 | field | $@ | accessors_instance.swift:119:21:119:35 | source(...) | source(...) |
-| accessors_instance.swift:134:24:134:33 | ... .0 | accessors_instance.swift:138:13:138:27 | source(...) | accessors_instance.swift:134:24:134:33 | ... .0 | $@ | accessors_instance.swift:138:13:138:27 | source(...) | source(...) |
+| accessors_instance.swift:134:24:134:33 | ... .0 | accessors_instance.swift:142:13:142:27 | source(...) | accessors_instance.swift:134:24:134:33 | ... .0 | $@ | accessors_instance.swift:142:13:142:27 | source(...) | source(...) |
+| accessors_instance.swift:138:24:138:35 | ... .0 | accessors_instance.swift:143:14:143:28 | source(...) | accessors_instance.swift:138:24:138:35 | ... .0 | $@ | accessors_instance.swift:143:14:143:28 | source(...) | source(...) |
 | accessors_local.swift:8:10:8:10 | x | accessors_local.swift:7:21:7:34 | source(...) | accessors_local.swift:8:10:8:10 | x | $@ | accessors_local.swift:7:21:7:34 | source(...) | source(...) |
 | accessors_local.swift:17:10:17:10 | x | accessors_local.swift:15:15:15:28 | source(...) | accessors_local.swift:17:10:17:10 | x | $@ | accessors_local.swift:15:15:15:28 | source(...) | source(...) |
 | accessors_local.swift:25:10:25:10 | x | accessors_local.swift:22:15:22:28 | source(...) | accessors_local.swift:25:10:25:10 | x | $@ | accessors_local.swift:22:15:22:28 | source(...) | source(...) |

From 5b468f21a53a0c1ea6fdb187639da51bdf79befc Mon Sep 17 00:00:00 2001
From: Tom Hvitved <hvitved@github.com>
Date: Tue, 27 Oct 2026 20:58:22 +0100
Subject: [PATCH 2/3] Unified: Resolve accessor accesses in type inference

---
 .../internal/NameBindingPluginSwift.qll       |  12 +-
 .../unified/internal/dataflow/CallGraph.qll   |  21 +-
 .../internal/dataflow/DataFlowCall.qll        |  15 +-
 .../internal/dataflow/DataFlowPluginSwift.qll |   7 +-
 .../internal/typeinference/TypeInference.qll  |  86 ++++--
 .../internal/typeinference/TypeMention.qll    |  14 +-
 .../dataflow/accessors_instance.swift         |   8 +-
 .../dataflow/accessors_local.swift            |   4 +-
 .../test/library-tests/dataflow/test.expected |  31 +-
 .../type-inference/accessors.swift            | 192 ++++++++++++
 .../type-inference/type-inference.expected    | 281 ++++++++++++++++++
 .../type-inference/type-inference.ql          |  14 +-
 12 files changed, 609 insertions(+), 76 deletions(-)
 create mode 100644 unified/ql/test/library-tests/type-inference/accessors.swift

diff --git a/unified/ql/lib/codeql/unified/internal/NameBindingPluginSwift.qll b/unified/ql/lib/codeql/unified/internal/NameBindingPluginSwift.qll
index 103c8ff7d0a7..846bb2ba8c67 100644
--- a/unified/ql/lib/codeql/unified/internal/NameBindingPluginSwift.qll
+++ b/unified/ql/lib/codeql/unified/internal/NameBindingPluginSwift.qll
@@ -88,10 +88,16 @@ class NameBindingPluginSwift extends NameBindingPlugin {
     or
     not m instanceof GeneratedConstructor and
     result =
-      concat(int i, Parameter p |
-        p = m.(Callable).getParameter(i)
+      concat(int i, Parameter p, string name |
+        p = m.(Callable).getParameter(i) and
+        (
+          name = p.getExternalNameNode().getValue()
+          or
+          not exists(p.getExternalNameNode()) and
+          name = "_"
+        )
       |
-        p.getExternalNameNode().getValue(), "," order by i
+        name, "," order by i
       )
   }
 
diff --git a/unified/ql/lib/codeql/unified/internal/dataflow/CallGraph.qll b/unified/ql/lib/codeql/unified/internal/dataflow/CallGraph.qll
index bd8314dcaee6..b035a03c817a 100644
--- a/unified/ql/lib/codeql/unified/internal/dataflow/CallGraph.qll
+++ b/unified/ql/lib/codeql/unified/internal/dataflow/CallGraph.qll
@@ -7,26 +7,9 @@ private import codeql.unified.internal.ExprPositions
 DataFlowCallable viableCallable(DataFlowCall c) {
   result.asSourceCallable() = T::resolveCallTarget(c.asExplicitCall())
   or
-  result.asSourceCallable() = resolveAccessor(c.asGetterCall()).(GetterDeclaration)
+  result.asSourceCallable() = T::resolveAccessorAccess(c.asGetterCall()).(GetterDeclaration)
   or
-  result.asSourceCallable() = resolveAccessor(c.asSetterCall()).(SetterDeclaration)
+  result.asSourceCallable() = T::resolveAccessorAccess(c.asSetterCall()).(SetterDeclaration)
   or
   result.asSummarizedCallable().matchesCall(c.asExplicitCall())
 }
-
-bindingset[access]
-pragma[inline_late]
-private N::NamespaceNode resolveBase(MemberAccessExpr access) {
-  result.isInstanceMemberNamespace(T::inferType(access.getBase()).asClass())
-}
-
-private AccessorDeclaration resolveAccessor(Expr access) {
-  result.getNameNode() = N::getStaticBindingTargetFromRef(access)
-  or
-  not exists(N::getStaticBindingTargetFromRef(access)) and
-  exists(MemberAccessExpr m |
-    access = m and
-    // TODO: Make type inference own accessor-resolution. It also needs it internally.
-    resolveBase(m).getMember(m.getMemberName()).isMember(result)
-  )
-}
diff --git a/unified/ql/lib/codeql/unified/internal/dataflow/DataFlowCall.qll b/unified/ql/lib/codeql/unified/internal/dataflow/DataFlowCall.qll
index f99f1f90e37a..3d4b32e191fc 100644
--- a/unified/ql/lib/codeql/unified/internal/dataflow/DataFlowCall.qll
+++ b/unified/ql/lib/codeql/unified/internal/dataflow/DataFlowCall.qll
@@ -2,6 +2,7 @@ private import unified
 private import AllDataFlow
 private import codeql.unified.internal.ExprPositions
 private import codeql.unified.internal.NameBinding as N
+private import codeql.unified.internal.typeinference.TypeInference as T
 
 private newtype TDataFlowCall =
   TExplicitCall(CallExpr call) {
@@ -9,12 +10,7 @@ private newtype TDataFlowCall =
   } or
   TGetterCall(Expr expr) {
     hasResultValue(expr) and
-    (
-      N::getStaticBindingTargetFromRef(expr) = any(GetterDeclaration g).getNameNode()
-      or
-      // Assume a qualified member accesses might resolve to a getter.
-      expr instanceof MemberAccessExpr
-    )
+    T::resolveAccessorAccess(expr) instanceof GetterDeclaration
   } or
   TSetterCall(Expr expr) {
     (
@@ -24,12 +20,7 @@ private newtype TDataFlowCall =
       hasPostUpdateAfterCallOrAssign(expr, _) and
       mayWriteBackViaSetterCall(expr)
     ) and
-    (
-      N::getStaticBindingTargetFromRef(expr) = any(SetterDeclaration g).getNameNode()
-      or
-      // Assume a qualified member accesses might resolve to a setter.
-      expr instanceof MemberAccessExpr
-    )
+    T::resolveAccessorAccess(expr) instanceof SetterDeclaration
   } or
   TSummaryCall(SummarizedCallable callable, SummaryNode callee) {
     FlowSummaryOutput::summaryCallbackRange(callable, callee)
diff --git a/unified/ql/lib/codeql/unified/internal/dataflow/DataFlowPluginSwift.qll b/unified/ql/lib/codeql/unified/internal/dataflow/DataFlowPluginSwift.qll
index 3d021a2f7aa5..b71fbf16120c 100644
--- a/unified/ql/lib/codeql/unified/internal/dataflow/DataFlowPluginSwift.qll
+++ b/unified/ql/lib/codeql/unified/internal/dataflow/DataFlowPluginSwift.qll
@@ -13,11 +13,12 @@ private class SwiftDataFlowPlugin extends DataFlowPlugin {
     contents.asSingleton().asNamedMember() = "some.0"
   }
 
-  // Swift writes back mutated values of computed properties via their setter
+  // Swift writes back mutated values of computed value-type properties via their setter
   bindingset[expr]
   override predicate mayWriteBackViaSetterCall(Expr expr) {
-    isInWriteBackPosition(expr)
-    // TODO: Check that 'expr' has a value type. Reference types don't cause writebacks.
+    isInWriteBackPosition(expr) and
+    // conservative value-type check
+    not forex(T::Type t | t = T::inferType(expr) | t.asClass().hasModifier("class"))
   }
 
   override predicate exprStep(Expr expr1, Expr expr2, boolean mustFlow) {
diff --git a/unified/ql/lib/codeql/unified/internal/typeinference/TypeInference.qll b/unified/ql/lib/codeql/unified/internal/typeinference/TypeInference.qll
index c5572af2ae34..85a1c0281cfb 100644
--- a/unified/ql/lib/codeql/unified/internal/typeinference/TypeInference.qll
+++ b/unified/ql/lib/codeql/unified/internal/typeinference/TypeInference.qll
@@ -123,6 +123,8 @@ module Input3 implements InputSig3 {
   predicate cacheRevRef() {
     (exists(resolveFieldAccess(_)) implies any())
     or
+    (exists(resolveAccessorAccess(_)) implies any())
+    or
     (exists(resolveCallTarget(_)) implies any())
   }
 
@@ -252,20 +254,38 @@ module Input3 implements InputSig3 {
     override Location getLocation() { result = decl.getLocation() }
   }
 
-  class Field extends AstVariableDeclaration {
+  final class Field = FieldImpl;
+
+  abstract private class FieldImpl extends DeclarationImpl {
+    abstract AstNode getAstNode();
+  }
+
+  private class VariableDeclarationField extends FieldImpl, AstVariableDeclaration {
     ClassLikeDeclaration cls;
 
-    Field() { decl = cls.getAMember() }
+    VariableDeclarationField() { decl = cls.getAMember() }
+
+    override AstNode getAstNode() { result = this.getDecl() }
 
     override TypeMention getDeclaringType() { result = getClassLikeDeclarationTypeMention(cls) }
   }
 
-  private class EnumField_ extends Field {
+  private class EnumField_ extends VariableDeclarationField {
     override EnumField decl;
 
     override TypeMention getType() { result = decl.getEnum().getNameNode() }
   }
 
+  private class AccessorField extends FieldImpl, Callable {
+    private AccessorDeclaration accessor;
+
+    AccessorField() { accessor = this.getCallable() }
+
+    override TypeMention getType() { result = accessor.getReturnType() }
+
+    override AstNode getAstNode() { result = accessor }
+  }
+
   abstract class FieldAccess extends Expr {
     abstract Expr getReceiver();
 
@@ -275,7 +295,7 @@ module Input3 implements InputSig3 {
   pragma[nomagic]
   private predicate lookupMember0(MemberAccessExpr mae, ClassLikeDeclaration cls, string name) {
     not exists(getStaticBindingTargetFromRef(mae)) and // if a static member can be resolved, use it
-    cls = inferType(mae.getBase()).(ClassLikeDeclarationType).getClassLikeDeclaration() and
+    cls = inferType(mae.getBase()).asClass() and
     name = mae.getMemberName()
   }
 
@@ -303,7 +323,7 @@ module Input3 implements InputSig3 {
       // also mutual recursion
       exists(TupleType tuple, string name |
         this.isTupleProjection(tuple, name) and
-        result.getDecl() = tuple.getField(name)
+        result.getAstNode() = tuple.getField(name)
       )
       or
       // no mutual recursion; can be resolved directly with static name binding
@@ -325,6 +345,18 @@ module Input3 implements InputSig3 {
     override Field getField() { result.getNameNode() = this.getTarget() }
   }
 
+  private class LocalAccessorFieldAccess extends FieldAccess, LocalNameAccess {
+    AccessorDeclaration target;
+
+    LocalAccessorFieldAccess() {
+      target = getStaticBindingTargetFromIdentifier(this).getDeclaration()
+    }
+
+    override Expr getReceiver() { none() }
+
+    override Field getField() { result.getAstNode() = target }
+  }
+
   Type inferFieldAccessReceiverType(FieldAccess fa, TypePath path) {
     // instance field with explicit receiver
     result = inferType(fa.getReceiver(), path)
@@ -506,17 +538,21 @@ module Input3 implements InputSig3 {
     }
 
     Callable getTargetImpl(boolean isFunctionExprInvoke) {
-      // mutual recursion; call with explicit receiver: `obj.foo(42)`
-      result = lookupInstanceMember(this.getCallee()) and
-      isFunctionExprInvoke = false
-      or
-      // mutual recursion; call to a function expression: `callback(42)`
-      result.asCallable() = this.getInvokeTarget(_) and
-      isFunctionExprInvoke = true
-      or
-      // no mutual recursion; can be resolved directly with static name binding
-      result = this.getTargetViaStaticNameBinding() and
-      isFunctionExprInvoke = false
+      (
+        // mutual recursion; call with explicit receiver: `obj.foo(42)`
+        result = lookupInstanceMember(this.getCallee()) and
+        isFunctionExprInvoke = false
+        or
+        // mutual recursion; call to a function expression: `callback(42)`
+        result.asCallable() = this.getInvokeTarget(_) and
+        isFunctionExprInvoke = true
+        or
+        // no mutual recursion; can be resolved directly with static name binding
+        result = this.getTargetViaStaticNameBinding() and
+        isFunctionExprInvoke = false
+      ) and
+      // handled as a field access
+      not result.asCallable() instanceof AccessorDeclaration
     }
 
     Callable getTarget(InvocationResolutionContext c) {
@@ -835,7 +871,23 @@ module CachedStage = M3::CachedStage;
 cached
 VariableDeclaration resolveFieldAccess(Expr access) {
   CachedStage::ref() and
-  result = access.(Input3::FieldAccess).getField().getDecl()
+  result = access.(Input3::FieldAccess).getField().getAstNode()
+}
+
+/**
+ * Gets the accessor that is accessed by the given expression.
+ *
+ * Note that we do not attempt to distinguish between different kinds of
+ * accessors; all accessors belonging to the same declaration will be
+ * returned (for example both the getter and setter of a property).
+ *
+ * `access` is either a `MemberAccessExpr` or an `Identifier` (when
+ * the field is accessed with an implicit receiver).
+ */
+cached
+AccessorDeclaration resolveAccessorAccess(Expr access) {
+  CachedStage::ref() and
+  result = access.(Input3::FieldAccess).getField().getAstNode()
 }
 
 /**
diff --git a/unified/ql/lib/codeql/unified/internal/typeinference/TypeMention.qll b/unified/ql/lib/codeql/unified/internal/typeinference/TypeMention.qll
index aa48459feeb0..baef8f970e26 100644
--- a/unified/ql/lib/codeql/unified/internal/typeinference/TypeMention.qll
+++ b/unified/ql/lib/codeql/unified/internal/typeinference/TypeMention.qll
@@ -24,7 +24,11 @@ abstract private class TypeMentionImpl extends AstNode {
 final class ExprTypeMention = ExprTypeMentionImpl;
 
 abstract private class ExprTypeMentionImpl extends TypeMentionImpl, Expr {
-  ExprTypeMentionImpl() { isInTypeContext(this) and not this instanceof GenericTypeExpr }
+  ExprTypeMentionImpl() {
+    isInTypeContext(this) and
+    not this instanceof GenericTypeExpr and
+    not this instanceof ModifiedTypeExpr
+  }
 
   pragma[nomagic]
   abstract TypePath getTypeArgumentPath(int i);
@@ -191,6 +195,14 @@ private class ClassLikeDeclarationTypeMention extends TypeMentionImpl, Identifie
   }
 }
 
+private class ModifiedTypeExprMention extends TypeMentionImpl instanceof ModifiedTypeExpr {
+  private TypeMention base;
+
+  ModifiedTypeExprMention() { base = ModifiedTypeExpr.super.getType() }
+
+  override Type getTypeAt(TypePath path) { result = base.getTypeAt(path) }
+}
+
 TypeMention getClassLikeDeclarationTypeMention(ClassLikeDeclaration c) {
   result = c.getNameNode()
   or
diff --git a/unified/ql/test/library-tests/dataflow/accessors_instance.swift b/unified/ql/test/library-tests/dataflow/accessors_instance.swift
index b4bcd8125c1b..b9daa47f45b5 100644
--- a/unified/ql/test/library-tests/dataflow/accessors_instance.swift
+++ b/unified/ql/test/library-tests/dataflow/accessors_instance.swift
@@ -131,11 +131,11 @@ func t11() {
     class C {
         var p: (String, String) {
             get { ("safe", "safe") }
-            set { sink(newValue.0) }  // $ hasValueFlow=t11.1 $ MISSING: hasValueFlow=t11.2
+            set { sink(newValue.0) }  // $ hasValueFlow=t11.1 hasValueFlow=t11.2
         }
         var q: C {
             get { C() }
-            set { sink(newValue.p.0) }  // $ SPURIOUS: hasValueFlow=t11.2
+            set { sink(newValue.p.0) }
         }
     }
     let c = C()
@@ -151,9 +151,9 @@ func t12() {
     class C {
         var s: S {
             get { S() }
-            set { sink(newValue.field) }  // $ MISSING: hasValueFlow=t12.1
+            set { sink(newValue.field) }  // $ hasValueFlow=t12.1
         }
     }
     let c = C()
-    c.s.update()  // MISSING: the call to 'update' is not resolved
+    c.s.update()
 }
diff --git a/unified/ql/test/library-tests/dataflow/accessors_local.swift b/unified/ql/test/library-tests/dataflow/accessors_local.swift
index 51c5a62e2894..0cfa68c3abce 100644
--- a/unified/ql/test/library-tests/dataflow/accessors_local.swift
+++ b/unified/ql/test/library-tests/dataflow/accessors_local.swift
@@ -100,9 +100,7 @@ func t12() {
     }
     var p: S {
         get { S() }
-        set { sink(newValue.field) }  // $ MISSING: hasValueFlow=t12.1
+        set { sink(newValue.field) }  // $ hasValueFlow=t12.1
     }
-    // TODO: test fails because the call to 'mutate' is not yet resolved
-    // At the time of writing, the test passes if the call graph is manually patched
     p.mutate()
 }
diff --git a/unified/ql/test/library-tests/dataflow/test.expected b/unified/ql/test/library-tests/dataflow/test.expected
index 5b3c0d3e6065..2af1a83d8f56 100644
--- a/unified/ql/test/library-tests/dataflow/test.expected
+++ b/unified/ql/test/library-tests/dataflow/test.expected
@@ -32,15 +32,16 @@ edges
 | accessors_instance.swift:119:13:119:17 | field | accessors_instance.swift:125:18:125:22 | field | provenance |  |
 | accessors_instance.swift:119:21:119:35 | source(...) | accessors_instance.swift:119:13:119:17 | field | provenance |  |
 | accessors_instance.swift:134:24:134:31 | newValue [0] | accessors_instance.swift:134:24:134:33 | ... .0 | provenance |  |
-| accessors_instance.swift:138:24:138:31 | newValue [p, 0] | accessors_instance.swift:138:24:138:33 | ... .p [0] | provenance |  |
-| accessors_instance.swift:138:24:138:33 | ... .p [0] | accessors_instance.swift:138:24:138:35 | ... .0 | provenance |  |
 | accessors_instance.swift:142:5:142:7 | [post] ... .p [0] | accessors_instance.swift:134:24:134:31 | newValue [0] | provenance |  |
 | accessors_instance.swift:142:5:142:9 | ... .0 | accessors_instance.swift:142:5:142:7 | [post] ... .p [0] | provenance |  |
 | accessors_instance.swift:142:13:142:27 | source(...) | accessors_instance.swift:142:5:142:9 | ... .0 | provenance |  |
-| accessors_instance.swift:143:5:143:7 | [post] ... .q [p, 0] | accessors_instance.swift:138:24:138:31 | newValue [p, 0] | provenance |  |
-| accessors_instance.swift:143:5:143:9 | ... .p [0] | accessors_instance.swift:143:5:143:7 | [post] ... .q [p, 0] | provenance |  |
+| accessors_instance.swift:143:5:143:9 | ... .p [0] | accessors_instance.swift:134:24:134:31 | newValue [0] | provenance |  |
 | accessors_instance.swift:143:13:143:46 | TupleExpr [0] | accessors_instance.swift:143:5:143:9 | ... .p [0] | provenance |  |
 | accessors_instance.swift:143:14:143:28 | source(...) | accessors_instance.swift:143:13:143:46 | TupleExpr [0] | provenance |  |
+| accessors_instance.swift:149:34:149:38 | field | accessors_instance.swift:158:5:158:7 | [post] ... .s [field] | provenance |  |
+| accessors_instance.swift:149:42:149:56 | source(...) | accessors_instance.swift:149:34:149:38 | field | provenance |  |
+| accessors_instance.swift:154:24:154:31 | newValue [field] | accessors_instance.swift:154:24:154:37 | ... .field | provenance |  |
+| accessors_instance.swift:158:5:158:7 | [post] ... .s [field] | accessors_instance.swift:154:24:154:31 | newValue [field] | provenance |  |
 | accessors_local.swift:7:21:7:34 | source(...) | accessors_local.swift:8:10:8:10 | x | provenance |  |
 | accessors_local.swift:15:15:15:28 | source(...) | accessors_local.swift:17:10:17:10 | x | provenance |  |
 | accessors_local.swift:22:15:22:28 | source(...) | accessors_local.swift:25:10:25:10 | x | provenance |  |
@@ -64,6 +65,10 @@ edges
 | accessors_local.swift:93:5:93:5 | [post] p [0] | accessors_local.swift:91:20:91:27 | newValue [0] | provenance |  |
 | accessors_local.swift:93:5:93:7 | ... .0 | accessors_local.swift:93:5:93:5 | [post] p [0] | provenance |  |
 | accessors_local.swift:93:11:93:25 | source(...) | accessors_local.swift:93:5:93:7 | ... .0 | provenance |  |
+| accessors_local.swift:99:34:99:38 | field | accessors_local.swift:105:5:105:5 | [post] p [field] | provenance |  |
+| accessors_local.swift:99:42:99:56 | source(...) | accessors_local.swift:99:34:99:38 | field | provenance |  |
+| accessors_local.swift:103:20:103:27 | newValue [field] | accessors_local.swift:103:20:103:33 | ... .field | provenance |  |
+| accessors_local.swift:105:5:105:5 | [post] p [field] | accessors_local.swift:103:20:103:27 | newValue [field] | provenance |  |
 | accessors_static.swift:8:32:8:45 | source(...) | accessors_static.swift:10:10:10:12 | ... .x | provenance |  |
 | accessors_static.swift:18:19:18:32 | source(...) | accessors_static.swift:21:10:21:12 | ... .x | provenance |  |
 | accessors_static.swift:27:19:27:32 | source(...) | accessors_static.swift:31:10:31:12 | ... .x | provenance |  |
@@ -564,16 +569,17 @@ nodes
 | accessors_instance.swift:125:18:125:22 | field | semmle.label | field |
 | accessors_instance.swift:134:24:134:31 | newValue [0] | semmle.label | newValue [0] |
 | accessors_instance.swift:134:24:134:33 | ... .0 | semmle.label | ... .0 |
-| accessors_instance.swift:138:24:138:31 | newValue [p, 0] | semmle.label | newValue [p, 0] |
-| accessors_instance.swift:138:24:138:33 | ... .p [0] | semmle.label | ... .p [0] |
-| accessors_instance.swift:138:24:138:35 | ... .0 | semmle.label | ... .0 |
 | accessors_instance.swift:142:5:142:7 | [post] ... .p [0] | semmle.label | [post] ... .p [0] |
 | accessors_instance.swift:142:5:142:9 | ... .0 | semmle.label | ... .0 |
 | accessors_instance.swift:142:13:142:27 | source(...) | semmle.label | source(...) |
-| accessors_instance.swift:143:5:143:7 | [post] ... .q [p, 0] | semmle.label | [post] ... .q [p, 0] |
 | accessors_instance.swift:143:5:143:9 | ... .p [0] | semmle.label | ... .p [0] |
 | accessors_instance.swift:143:13:143:46 | TupleExpr [0] | semmle.label | TupleExpr [0] |
 | accessors_instance.swift:143:14:143:28 | source(...) | semmle.label | source(...) |
+| accessors_instance.swift:149:34:149:38 | field | semmle.label | field |
+| accessors_instance.swift:149:42:149:56 | source(...) | semmle.label | source(...) |
+| accessors_instance.swift:154:24:154:31 | newValue [field] | semmle.label | newValue [field] |
+| accessors_instance.swift:154:24:154:37 | ... .field | semmle.label | ... .field |
+| accessors_instance.swift:158:5:158:7 | [post] ... .s [field] | semmle.label | [post] ... .s [field] |
 | accessors_local.swift:7:21:7:34 | source(...) | semmle.label | source(...) |
 | accessors_local.swift:8:10:8:10 | x | semmle.label | x |
 | accessors_local.swift:15:15:15:28 | source(...) | semmle.label | source(...) |
@@ -608,6 +614,11 @@ nodes
 | accessors_local.swift:93:5:93:5 | [post] p [0] | semmle.label | [post] p [0] |
 | accessors_local.swift:93:5:93:7 | ... .0 | semmle.label | ... .0 |
 | accessors_local.swift:93:11:93:25 | source(...) | semmle.label | source(...) |
+| accessors_local.swift:99:34:99:38 | field | semmle.label | field |
+| accessors_local.swift:99:42:99:56 | source(...) | semmle.label | source(...) |
+| accessors_local.swift:103:20:103:27 | newValue [field] | semmle.label | newValue [field] |
+| accessors_local.swift:103:20:103:33 | ... .field | semmle.label | ... .field |
+| accessors_local.swift:105:5:105:5 | [post] p [field] | semmle.label | [post] p [field] |
 | accessors_static.swift:8:32:8:45 | source(...) | semmle.label | source(...) |
 | accessors_static.swift:10:10:10:12 | ... .x | semmle.label | ... .x |
 | accessors_static.swift:18:19:18:32 | source(...) | semmle.label | source(...) |
@@ -1205,7 +1216,8 @@ testFailures
 | accessors_instance.swift:112:10:112:16 | ... .field | accessors_instance.swift:106:21:106:34 | source(...) | accessors_instance.swift:112:10:112:16 | ... .field | $@ | accessors_instance.swift:106:21:106:34 | source(...) | source(...) |
 | accessors_instance.swift:125:18:125:22 | field | accessors_instance.swift:119:21:119:35 | source(...) | accessors_instance.swift:125:18:125:22 | field | $@ | accessors_instance.swift:119:21:119:35 | source(...) | source(...) |
 | accessors_instance.swift:134:24:134:33 | ... .0 | accessors_instance.swift:142:13:142:27 | source(...) | accessors_instance.swift:134:24:134:33 | ... .0 | $@ | accessors_instance.swift:142:13:142:27 | source(...) | source(...) |
-| accessors_instance.swift:138:24:138:35 | ... .0 | accessors_instance.swift:143:14:143:28 | source(...) | accessors_instance.swift:138:24:138:35 | ... .0 | $@ | accessors_instance.swift:143:14:143:28 | source(...) | source(...) |
+| accessors_instance.swift:134:24:134:33 | ... .0 | accessors_instance.swift:143:14:143:28 | source(...) | accessors_instance.swift:134:24:134:33 | ... .0 | $@ | accessors_instance.swift:143:14:143:28 | source(...) | source(...) |
+| accessors_instance.swift:154:24:154:37 | ... .field | accessors_instance.swift:149:42:149:56 | source(...) | accessors_instance.swift:154:24:154:37 | ... .field | $@ | accessors_instance.swift:149:42:149:56 | source(...) | source(...) |
 | accessors_local.swift:8:10:8:10 | x | accessors_local.swift:7:21:7:34 | source(...) | accessors_local.swift:8:10:8:10 | x | $@ | accessors_local.swift:7:21:7:34 | source(...) | source(...) |
 | accessors_local.swift:17:10:17:10 | x | accessors_local.swift:15:15:15:28 | source(...) | accessors_local.swift:17:10:17:10 | x | $@ | accessors_local.swift:15:15:15:28 | source(...) | source(...) |
 | accessors_local.swift:25:10:25:10 | x | accessors_local.swift:22:15:22:28 | source(...) | accessors_local.swift:25:10:25:10 | x | $@ | accessors_local.swift:22:15:22:28 | source(...) | source(...) |
@@ -1217,6 +1229,7 @@ testFailures
 | accessors_local.swift:70:14:70:14 | x | accessors_local.swift:72:9:72:22 | source(...) | accessors_local.swift:70:14:70:14 | x | $@ | accessors_local.swift:72:9:72:22 | source(...) | source(...) |
 | accessors_local.swift:82:14:82:15 | x3 | accessors_local.swift:84:9:84:22 | source(...) | accessors_local.swift:82:14:82:15 | x3 | $@ | accessors_local.swift:84:9:84:22 | source(...) | source(...) |
 | accessors_local.swift:91:20:91:29 | ... .0 | accessors_local.swift:93:11:93:25 | source(...) | accessors_local.swift:91:20:91:29 | ... .0 | $@ | accessors_local.swift:93:11:93:25 | source(...) | source(...) |
+| accessors_local.swift:103:20:103:33 | ... .field | accessors_local.swift:99:42:99:56 | source(...) | accessors_local.swift:103:20:103:33 | ... .field | $@ | accessors_local.swift:99:42:99:56 | source(...) | source(...) |
 | accessors_static.swift:10:10:10:12 | ... .x | accessors_static.swift:8:32:8:45 | source(...) | accessors_static.swift:10:10:10:12 | ... .x | $@ | accessors_static.swift:8:32:8:45 | source(...) | source(...) |
 | accessors_static.swift:21:10:21:12 | ... .x | accessors_static.swift:18:19:18:32 | source(...) | accessors_static.swift:21:10:21:12 | ... .x | $@ | accessors_static.swift:18:19:18:32 | source(...) | source(...) |
 | accessors_static.swift:31:10:31:12 | ... .x | accessors_static.swift:27:19:27:32 | source(...) | accessors_static.swift:31:10:31:12 | ... .x | $@ | accessors_static.swift:27:19:27:32 | source(...) | source(...) |
diff --git a/unified/ql/test/library-tests/type-inference/accessors.swift b/unified/ql/test/library-tests/type-inference/accessors.swift
new file mode 100644
index 000000000000..eee4b8e14207
--- /dev/null
+++ b/unified/ql/test/library-tests/type-inference/accessors.swift
@@ -0,0 +1,192 @@
+// --- Computed properties ---
+
+class AccessorContainer {
+  var stored: Int = 0
+
+  var implicitGetter: Int {
+    return stored  // $ type=stored:Int field=AccessorContainer.stored
+  }
+
+  var explicitGetter: String {
+    let value = "accessor"  // $ type=value:String
+    return value  // $ type=value:String
+  }
+
+  var writable: Int {
+    get {
+      return stored  // $ type=stored:Int field=AccessorContainer.stored
+    }
+    set {
+      stored = newValue  // $ field=AccessorContainer.stored type=newValue:Int
+    }
+  }
+
+  var namedSetter: Int {
+    get {
+      return stored  // $ type=stored:Int field=AccessorContainer.stored
+    }
+    set(value) {
+      stored = value  // $ field=AccessorContainer.stored type=value:Int
+    }
+  }
+}
+
+func testComputedProperties() {
+  let container = AccessorContainer()  // $ target=AccessorContainer.init
+  let implicitValue = container.implicitGetter  // $ type=implicitValue:Int accessor=AccessorContainer.implicitGetter
+  let explicitValue = container.explicitGetter  // $ type=explicitValue:String accessor=AccessorContainer.explicitGetter
+  let writableValue = container.writable  // $ type=writableValue:Int accessor=AccessorContainer.writable
+  container.writable = 42  // $ accessor=AccessorContainer.writable
+  container.writable += 0  // $ accessor=AccessorContainer.writable accessor=AccessorContainer.writable
+  let namedValue = container.namedSetter  // $ type=namedValue:Int accessor=AccessorContainer.namedSetter
+  container.namedSetter = 43  // $ accessor=AccessorContainer.namedSetter
+}
+
+// --- Stored properties with observers ---
+
+class ObservedProperties {
+  var observed: Int = 0 {
+    willSet {
+      let current = observed  // $ type=current:Int field=ObservedProperties.observed accessor=ObservedProperties.observed
+      let incoming = newValue  // $ type=incoming:Int
+    }
+    didSet {
+      let current = observed  // $ type=current:Int field=ObservedProperties.observed accessor=ObservedProperties.observed
+      let previous = oldValue  // $ type=previous:Int
+    }
+  }
+
+  var namedObservers: String = "" {
+    willSet(incoming) {
+      let value = incoming  // $ type=value:String
+    }
+    didSet(previous) {
+      let value = previous  // $ type=value:String
+    }
+  }
+}
+
+func testObservedProperties() {
+  let container = ObservedProperties()  // $ target=ObservedProperties.init
+  let observed = container.observed  // $ type=observed:Int accessor=ObservedProperties.observed field=ObservedProperties.observed
+  container.observed = 42  // $ accessor=ObservedProperties.observed field=ObservedProperties.observed
+  let named = container.namedObservers  // $ type=named:String accessor=ObservedProperties.namedObservers field=ObservedProperties.namedObservers
+  container.namedObservers = "updated"  // $ accessor=ObservedProperties.namedObservers field=ObservedProperties.namedObservers
+}
+
+// --- Generic and inherited accessors ---
+
+class GenericAccessors<T> {
+  var stored: T
+
+  init(value: T) {
+    stored = value  // $ type=value:T field=GenericAccessors.stored
+  }
+
+  var value: T {
+    get {
+      return stored  // $ type=stored:T field=GenericAccessors.stored
+    }
+    set {
+      stored = newValue  // $ field=GenericAccessors.stored type=newValue:T
+    }
+  }
+
+  var observed: Int = 0 {
+    didSet {
+      let current = observed  // $ type=current:Int field=GenericAccessors.observed accessor=GenericAccessors.observed
+      let previous = oldValue  // $ type=previous:Int
+    }
+  }
+}
+
+class InheritedAccessors: GenericAccessors<Int> {
+  override var observed: Int {
+    didSet {
+      let current = observed  // $ accessor=InheritedAccessors.observed $ MISSING: type=current:Int field=GenericAccessors.observed -- static name binding is currently unable to resolve the access to the backing field
+      let current2 = self.observed  // $ accessor=InheritedAccessors.observed type=current2:Int field=GenericAccessors.observed
+      let previous = oldValue  // $ type=previous:Int
+    }
+  }
+}
+
+extension GenericAccessors {
+  var extensionValue: T {
+    return stored  // $ field=GenericAccessors.stored $ MISSING: type=stored:T
+  }
+}
+
+func testGenericAccessors() {
+  let container = GenericAccessors(value: "value")  // $ target=GenericAccessors.init
+  let value = container.value  // $ type=value:String accessor=GenericAccessors.value
+  let extensionValue = container.extensionValue  // $ accessor=GenericAccessors.extensionValue $ MISSING: type=extensionValue:String
+  let inherited = InheritedAccessors(value: 42)  // $ target=GenericAccessors.init
+  let inheritedValue = inherited.value  // $ type=inheritedValue:Int accessor=GenericAccessors.value
+  let inheritedObserver = inherited.observed  // $ type=inheritedObserver:Int field=GenericAccessors.observed accessor=InheritedAccessors.observed
+}
+
+// --- Protocol accessor requirements ---
+
+protocol AccessorRequirements {
+  var readOnly: Int { get }
+  var readWrite: String { get set }
+}
+
+func testAccessorRequirements(_ value: inout AccessorRequirements) {
+  let readOnly = value.readOnly  // $ type=readOnly:Int accessor=AccessorRequirements.readOnly
+  let readWrite = value.readWrite  // $ type=readWrite:String accessor=AccessorRequirements.readWrite
+  value.readWrite = "updated"  // $ accessor=AccessorRequirements.readWrite
+}
+
+// --- Function-valued properties ---
+class C {
+  var callback: () -> String { { "x" } }
+
+  func f() {
+    let result = callback()  // $ type=result:String accessor=C.callback target=Function.callAsFunction
+    let result2 = self.callback()  // $ type=result2:String accessor=C.callback target=Function.callAsFunction
+  }
+}
+
+// --- Static and class accessors ---
+
+class StaticAccessors {
+  static var stored: Int = 0
+
+  static var value: Int {
+    get {
+      return stored  // $ type=stored:Int field=StaticAccessors.stored
+    }
+    set {
+      stored = newValue  // $ field=StaticAccessors.stored type=newValue:Int
+    }
+  }
+}
+
+func testStaticAccessors() {
+  let value = StaticAccessors.value  // $ type=value:Int accessor=StaticAccessors.value
+  StaticAccessors.value = 42  // $ accessor=StaticAccessors.value
+}
+
+class ClassAccessors {
+  static var stored: Int = 0
+
+  class var value: Int {
+    get {
+      return stored  // $ type=stored:Int field=ClassAccessors.stored
+    }
+    set {
+      stored = newValue  // $ field=ClassAccessors.stored type=newValue:Int
+    }
+  }
+}
+
+func testClassAccessors() {
+  let value = ClassAccessors.value  // $ type=value:Int accessor=ClassAccessors.value
+  ClassAccessors.value = 42  // $ accessor=ClassAccessors.value
+}
+
+// --- Top-level accessors ---
+
+var answer: Int { 42 }
+let x = answer  // $ type=x:Int accessor=answer
diff --git a/unified/ql/test/library-tests/type-inference/type-inference.expected b/unified/ql/test/library-tests/type-inference/type-inference.expected
index 3ce1618a9164..b88ac707d220 100644
--- a/unified/ql/test/library-tests/type-inference/type-inference.expected
+++ b/unified/ql/test/library-tests/type-inference/type-inference.expected
@@ -1,4 +1,59 @@
 inferCertainType
+| accessors.swift:4:7:4:12 | stored |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:7:12:7:17 | stored |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:17:14:17:19 | stored |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:20:7:20:12 | stored |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:20:16:20:23 | newValue |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:26:14:26:19 | stored |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:28:9:28:13 | value |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:29:7:29:12 | stored |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:29:16:29:20 | value |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:48:7:48:14 | observed |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:50:11:50:17 | current |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:50:21:50:28 | observed |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:51:11:51:18 | incoming |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:51:22:51:29 | newValue |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:54:11:54:17 | current |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:54:21:54:28 | observed |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:55:11:55:18 | previous |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:55:22:55:29 | oldValue |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:59:7:59:20 | namedObservers |  | {EXTERNAL LOCATION} | String |
+| accessors.swift:60:13:60:20 | incoming |  | {EXTERNAL LOCATION} | String |
+| accessors.swift:61:11:61:15 | value |  | {EXTERNAL LOCATION} | String |
+| accessors.swift:61:19:61:26 | incoming |  | {EXTERNAL LOCATION} | String |
+| accessors.swift:63:12:63:19 | previous |  | {EXTERNAL LOCATION} | String |
+| accessors.swift:64:11:64:15 | value |  | {EXTERNAL LOCATION} | String |
+| accessors.swift:64:19:64:26 | previous |  | {EXTERNAL LOCATION} | String |
+| accessors.swift:80:7:80:12 | stored |  | accessors.swift:79:24:79:24 | T |
+| accessors.swift:82:8:82:12 | value |  | accessors.swift:79:24:79:24 | T |
+| accessors.swift:83:5:83:10 | stored |  | accessors.swift:79:24:79:24 | T |
+| accessors.swift:83:14:83:18 | value |  | accessors.swift:79:24:79:24 | T |
+| accessors.swift:88:14:88:19 | stored |  | accessors.swift:79:24:79:24 | T |
+| accessors.swift:91:7:91:12 | stored |  | accessors.swift:79:24:79:24 | T |
+| accessors.swift:91:16:91:23 | newValue |  | accessors.swift:79:24:79:24 | T |
+| accessors.swift:95:7:95:14 | observed |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:97:11:97:17 | current |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:97:21:97:28 | observed |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:98:11:98:18 | previous |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:98:22:98:29 | oldValue |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:107:22:107:25 | self |  | accessors.swift:103:1:111:1 | InheritedAccessors |
+| accessors.swift:108:11:108:18 | previous |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:108:22:108:29 | oldValue |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:135:33:135:37 | value |  | accessors.swift:130:1:133:1 | AccessorRequirements |
+| accessors.swift:136:18:136:22 | value |  | accessors.swift:130:1:133:1 | AccessorRequirements |
+| accessors.swift:137:19:137:23 | value |  | accessors.swift:130:1:133:1 | AccessorRequirements |
+| accessors.swift:138:3:138:7 | value |  | accessors.swift:130:1:133:1 | AccessorRequirements |
+| accessors.swift:143:30:143:40 | Block |  | {EXTERNAL LOCATION} | Function |
+| accessors.swift:143:32:143:38 | FunctionExpr |  | {EXTERNAL LOCATION} | Function |
+| accessors.swift:147:19:147:22 | self |  | accessors.swift:142:1:149:1 | C |
+| accessors.swift:154:14:154:19 | stored |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:158:14:158:19 | stored |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:161:7:161:12 | stored |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:161:16:161:23 | newValue |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:172:14:172:19 | stored |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:176:14:176:19 | stored |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:179:7:179:12 | stored |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:179:16:179:23 | newValue |  | {EXTERNAL LOCATION} | Int |
 | basics.swift:1:5:1:16 | topLevelDecl |  | {EXTERNAL LOCATION} | Int |
 | basics.swift:3:1:3:12 | topLevelDecl |  | {EXTERNAL LOCATION} | Int |
 | basics.swift:6:7:6:11 | myInt |  | {EXTERNAL LOCATION} | Int |
@@ -103,8 +158,20 @@ inferCertainType
 | closures.swift:38:9:38:10 | f2 | Args | {EXTERNAL LOCATION} | Tuple1 |
 | closures.swift:38:9:38:10 | f2 | Args.T0 | {EXTERNAL LOCATION} | Int |
 | closures.swift:38:9:38:10 | f2 | Return | {EXTERNAL LOCATION} | Int |
+| closures.swift:40:10:40:10 | f |  | {EXTERNAL LOCATION} | Function |
+| closures.swift:40:10:40:10 | f | Args | {EXTERNAL LOCATION} | Tuple1 |
+| closures.swift:40:10:40:10 | f | Args.T0 | {EXTERNAL LOCATION} | Int |
+| closures.swift:40:10:40:10 | f | Return | {EXTERNAL LOCATION} | Int |
 | closures.swift:41:9:41:12 | self |  | closures.swift:31:1:50:1 | ClosureField |
+| closures.swift:41:18:41:18 | f |  | {EXTERNAL LOCATION} | Function |
+| closures.swift:41:18:41:18 | f | Args | {EXTERNAL LOCATION} | Tuple1 |
+| closures.swift:41:18:41:18 | f | Args.T0 | {EXTERNAL LOCATION} | Int |
+| closures.swift:41:18:41:18 | f | Return | {EXTERNAL LOCATION} | Int |
 | closures.swift:42:9:42:12 | self |  | closures.swift:31:1:50:1 | ClosureField |
+| closures.swift:42:19:42:19 | f |  | {EXTERNAL LOCATION} | Function |
+| closures.swift:42:19:42:19 | f | Args | {EXTERNAL LOCATION} | Tuple1 |
+| closures.swift:42:19:42:19 | f | Args.T0 | {EXTERNAL LOCATION} | Int |
+| closures.swift:42:19:42:19 | f | Return | {EXTERNAL LOCATION} | Int |
 | closures.swift:45:24:45:28 | value |  | {EXTERNAL LOCATION} | Int |
 | closures.swift:47:9:47:12 | self |  | closures.swift:31:1:50:1 | ClosureField |
 | closures.swift:47:16:47:20 | value |  | {EXTERNAL LOCATION} | Int |
@@ -686,6 +753,196 @@ inferCertainType
 | type_constraints.swift:256:29:256:33 | upper |  | type_constraints.swift:254:12:254:24 | T |
 | type_constraints.swift:257:10:257:14 | value |  | type_constraints.swift:254:12:254:24 | T |
 inferType
+| accessors.swift:4:7:4:12 | stored |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:4:21:4:21 | 0 |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:6:27:8:3 | Block |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:7:12:7:17 | stored |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:10:30:13:3 | Block |  | {EXTERNAL LOCATION} | String |
+| accessors.swift:11:9:11:13 | value |  | {EXTERNAL LOCATION} | String |
+| accessors.swift:11:17:11:26 | "accessor" |  | {EXTERNAL LOCATION} | String |
+| accessors.swift:12:12:12:16 | value |  | {EXTERNAL LOCATION} | String |
+| accessors.swift:16:9:18:5 | Block |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:17:14:17:19 | stored |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:19:9:21:5 | Block |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:20:7:20:12 | stored |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:20:7:20:23 | ... = ... |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:20:16:20:23 | newValue |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:25:9:27:5 | Block |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:26:14:26:19 | stored |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:28:9:28:13 | value |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:28:16:30:5 | Block |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:29:7:29:12 | stored |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:29:7:29:20 | ... = ... |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:29:16:29:20 | value |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:34:31:43:1 | Block |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:35:7:35:15 | container |  | accessors.swift:3:1:32:1 | AccessorContainer |
+| accessors.swift:35:19:35:35 | AccessorContainer |  | accessors.swift:3:1:32:1 | AccessorContainer |
+| accessors.swift:35:19:35:37 | AccessorContainer(...) |  | accessors.swift:3:1:32:1 | AccessorContainer |
+| accessors.swift:36:7:36:19 | implicitValue |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:36:23:36:31 | container |  | accessors.swift:3:1:32:1 | AccessorContainer |
+| accessors.swift:36:23:36:46 | ... .implicitGetter |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:37:7:37:19 | explicitValue |  | {EXTERNAL LOCATION} | String |
+| accessors.swift:37:23:37:31 | container |  | accessors.swift:3:1:32:1 | AccessorContainer |
+| accessors.swift:37:23:37:46 | ... .explicitGetter |  | {EXTERNAL LOCATION} | String |
+| accessors.swift:38:7:38:19 | writableValue |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:38:23:38:31 | container |  | accessors.swift:3:1:32:1 | AccessorContainer |
+| accessors.swift:38:23:38:40 | ... .writable |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:39:3:39:11 | container |  | accessors.swift:3:1:32:1 | AccessorContainer |
+| accessors.swift:39:3:39:20 | ... .writable |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:39:3:39:25 | ... = ... |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:39:24:39:25 | 42 |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:40:3:40:11 | container |  | accessors.swift:3:1:32:1 | AccessorContainer |
+| accessors.swift:40:3:40:20 | ... .writable |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:40:3:40:25 | ... += ... |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:40:25:40:25 | 0 |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:41:7:41:16 | namedValue |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:41:20:41:28 | container |  | accessors.swift:3:1:32:1 | AccessorContainer |
+| accessors.swift:41:20:41:40 | ... .namedSetter |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:42:3:42:11 | container |  | accessors.swift:3:1:32:1 | AccessorContainer |
+| accessors.swift:42:3:42:23 | ... .namedSetter |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:42:3:42:28 | ... = ... |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:42:27:42:28 | 43 |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:48:7:48:14 | observed |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:48:23:48:23 | 0 |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:50:11:50:17 | current |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:50:21:50:28 | observed |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:51:11:51:18 | incoming |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:51:22:51:29 | newValue |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:54:11:54:17 | current |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:54:21:54:28 | observed |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:55:11:55:18 | previous |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:55:22:55:29 | oldValue |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:59:7:59:20 | namedObservers |  | {EXTERNAL LOCATION} | String |
+| accessors.swift:59:32:59:33 | "" |  | {EXTERNAL LOCATION} | String |
+| accessors.swift:60:13:60:20 | incoming |  | {EXTERNAL LOCATION} | String |
+| accessors.swift:61:11:61:15 | value |  | {EXTERNAL LOCATION} | String |
+| accessors.swift:61:19:61:26 | incoming |  | {EXTERNAL LOCATION} | String |
+| accessors.swift:63:12:63:19 | previous |  | {EXTERNAL LOCATION} | String |
+| accessors.swift:64:11:64:15 | value |  | {EXTERNAL LOCATION} | String |
+| accessors.swift:64:19:64:26 | previous |  | {EXTERNAL LOCATION} | String |
+| accessors.swift:69:31:75:1 | Block |  | {EXTERNAL LOCATION} | String |
+| accessors.swift:70:7:70:15 | container |  | accessors.swift:47:1:67:1 | ObservedProperties |
+| accessors.swift:70:19:70:36 | ObservedProperties |  | accessors.swift:47:1:67:1 | ObservedProperties |
+| accessors.swift:70:19:70:38 | ObservedProperties(...) |  | accessors.swift:47:1:67:1 | ObservedProperties |
+| accessors.swift:71:7:71:14 | observed |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:71:18:71:26 | container |  | accessors.swift:47:1:67:1 | ObservedProperties |
+| accessors.swift:71:18:71:35 | ... .observed |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:72:3:72:11 | container |  | accessors.swift:47:1:67:1 | ObservedProperties |
+| accessors.swift:72:3:72:20 | ... .observed |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:72:3:72:25 | ... = ... |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:72:24:72:25 | 42 |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:73:7:73:11 | named |  | {EXTERNAL LOCATION} | String |
+| accessors.swift:73:15:73:23 | container |  | accessors.swift:47:1:67:1 | ObservedProperties |
+| accessors.swift:73:15:73:38 | ... .namedObservers |  | {EXTERNAL LOCATION} | String |
+| accessors.swift:74:3:74:11 | container |  | accessors.swift:47:1:67:1 | ObservedProperties |
+| accessors.swift:74:3:74:26 | ... .namedObservers |  | {EXTERNAL LOCATION} | String |
+| accessors.swift:74:3:74:38 | ... = ... |  | {EXTERNAL LOCATION} | String |
+| accessors.swift:74:30:74:38 | "updated" |  | {EXTERNAL LOCATION} | String |
+| accessors.swift:80:7:80:12 | stored |  | accessors.swift:79:24:79:24 | T |
+| accessors.swift:82:8:82:12 | value |  | accessors.swift:79:24:79:24 | T |
+| accessors.swift:82:18:84:3 | Block |  | accessors.swift:79:24:79:24 | T |
+| accessors.swift:83:5:83:10 | stored |  | accessors.swift:79:24:79:24 | T |
+| accessors.swift:83:5:83:18 | ... = ... |  | accessors.swift:79:24:79:24 | T |
+| accessors.swift:83:14:83:18 | value |  | accessors.swift:79:24:79:24 | T |
+| accessors.swift:87:9:89:5 | Block |  | accessors.swift:79:24:79:24 | T |
+| accessors.swift:88:14:88:19 | stored |  | accessors.swift:79:24:79:24 | T |
+| accessors.swift:90:9:92:5 | Block |  | accessors.swift:79:24:79:24 | T |
+| accessors.swift:91:7:91:12 | stored |  | accessors.swift:79:24:79:24 | T |
+| accessors.swift:91:7:91:23 | ... = ... |  | accessors.swift:79:24:79:24 | T |
+| accessors.swift:91:16:91:23 | newValue |  | accessors.swift:79:24:79:24 | T |
+| accessors.swift:95:7:95:14 | observed |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:95:23:95:23 | 0 |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:97:11:97:17 | current |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:97:21:97:28 | observed |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:98:11:98:18 | previous |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:98:22:98:29 | oldValue |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:107:11:107:18 | current2 |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:107:22:107:25 | self |  | accessors.swift:103:1:111:1 | InheritedAccessors |
+| accessors.swift:107:22:107:34 | ... .observed |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:108:11:108:18 | previous |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:108:22:108:29 | oldValue |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:120:7:120:15 | container |  | accessors.swift:79:1:101:1 | GenericAccessors |
+| accessors.swift:120:7:120:15 | container | T | {EXTERNAL LOCATION} | String |
+| accessors.swift:120:19:120:34 | GenericAccessors |  | accessors.swift:79:1:101:1 | GenericAccessors |
+| accessors.swift:120:19:120:34 | GenericAccessors | T | {EXTERNAL LOCATION} | String |
+| accessors.swift:120:19:120:50 | GenericAccessors(...) |  | accessors.swift:79:1:101:1 | GenericAccessors |
+| accessors.swift:120:19:120:50 | GenericAccessors(...) | T | {EXTERNAL LOCATION} | String |
+| accessors.swift:120:43:120:49 | "value" |  | {EXTERNAL LOCATION} | String |
+| accessors.swift:121:7:121:11 | value |  | {EXTERNAL LOCATION} | String |
+| accessors.swift:121:15:121:23 | container |  | accessors.swift:79:1:101:1 | GenericAccessors |
+| accessors.swift:121:15:121:23 | container | T | {EXTERNAL LOCATION} | String |
+| accessors.swift:121:15:121:29 | ... .value |  | {EXTERNAL LOCATION} | String |
+| accessors.swift:122:24:122:32 | container |  | accessors.swift:79:1:101:1 | GenericAccessors |
+| accessors.swift:122:24:122:32 | container | T | {EXTERNAL LOCATION} | String |
+| accessors.swift:123:7:123:15 | inherited |  | accessors.swift:103:1:111:1 | InheritedAccessors |
+| accessors.swift:123:19:123:36 | InheritedAccessors |  | accessors.swift:103:1:111:1 | InheritedAccessors |
+| accessors.swift:123:19:123:47 | InheritedAccessors(...) |  | accessors.swift:103:1:111:1 | InheritedAccessors |
+| accessors.swift:123:45:123:46 | 42 |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:124:7:124:20 | inheritedValue |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:124:24:124:32 | inherited |  | accessors.swift:103:1:111:1 | InheritedAccessors |
+| accessors.swift:124:24:124:38 | ... .value |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:125:7:125:23 | inheritedObserver |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:125:27:125:35 | inherited |  | accessors.swift:103:1:111:1 | InheritedAccessors |
+| accessors.swift:125:27:125:44 | ... .observed |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:135:33:135:37 | value |  | accessors.swift:130:1:133:1 | AccessorRequirements |
+| accessors.swift:135:68:139:1 | Block |  | {EXTERNAL LOCATION} | String |
+| accessors.swift:136:7:136:14 | readOnly |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:136:18:136:22 | value |  | accessors.swift:130:1:133:1 | AccessorRequirements |
+| accessors.swift:136:18:136:31 | ... .readOnly |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:137:7:137:15 | readWrite |  | {EXTERNAL LOCATION} | String |
+| accessors.swift:137:19:137:23 | value |  | accessors.swift:130:1:133:1 | AccessorRequirements |
+| accessors.swift:137:19:137:33 | ... .readWrite |  | {EXTERNAL LOCATION} | String |
+| accessors.swift:138:3:138:7 | value |  | accessors.swift:130:1:133:1 | AccessorRequirements |
+| accessors.swift:138:3:138:17 | ... .readWrite |  | {EXTERNAL LOCATION} | String |
+| accessors.swift:138:3:138:29 | ... = ... |  | {EXTERNAL LOCATION} | String |
+| accessors.swift:138:21:138:29 | "updated" |  | {EXTERNAL LOCATION} | String |
+| accessors.swift:143:30:143:40 | Block |  | {EXTERNAL LOCATION} | Function |
+| accessors.swift:143:30:143:40 | Block | Return | {EXTERNAL LOCATION} | String |
+| accessors.swift:143:32:143:38 | FunctionExpr |  | {EXTERNAL LOCATION} | Function |
+| accessors.swift:143:32:143:38 | FunctionExpr | Return | {EXTERNAL LOCATION} | String |
+| accessors.swift:143:34:143:36 | "x" |  | {EXTERNAL LOCATION} | String |
+| accessors.swift:143:34:143:36 | Block |  | {EXTERNAL LOCATION} | String |
+| accessors.swift:146:9:146:14 | result |  | {EXTERNAL LOCATION} | String |
+| accessors.swift:146:18:146:25 | callback |  | {EXTERNAL LOCATION} | Function |
+| accessors.swift:146:18:146:25 | callback | Return | {EXTERNAL LOCATION} | String |
+| accessors.swift:146:18:146:27 | callback(...) |  | {EXTERNAL LOCATION} | String |
+| accessors.swift:147:9:147:15 | result2 |  | {EXTERNAL LOCATION} | String |
+| accessors.swift:147:19:147:22 | self |  | accessors.swift:142:1:149:1 | C |
+| accessors.swift:147:19:147:31 | ... .callback |  | {EXTERNAL LOCATION} | Function |
+| accessors.swift:147:19:147:31 | ... .callback | Return | {EXTERNAL LOCATION} | String |
+| accessors.swift:147:19:147:33 | ... .callback(...) |  | {EXTERNAL LOCATION} | String |
+| accessors.swift:154:14:154:19 | stored |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:154:28:154:28 | 0 |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:157:9:159:5 | Block |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:158:14:158:19 | stored |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:160:9:162:5 | Block |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:161:7:161:12 | stored |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:161:7:161:23 | ... = ... |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:161:16:161:23 | newValue |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:166:28:169:1 | Block |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:167:7:167:11 | value |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:167:15:167:35 | ... .value |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:168:3:168:23 | ... .value |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:168:3:168:28 | ... = ... |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:168:27:168:28 | 42 |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:172:14:172:19 | stored |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:172:28:172:28 | 0 |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:175:9:177:5 | Block |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:176:14:176:19 | stored |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:178:9:180:5 | Block |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:179:7:179:12 | stored |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:179:7:179:23 | ... = ... |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:179:16:179:23 | newValue |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:184:27:187:1 | Block |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:185:7:185:11 | value |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:185:15:185:34 | ... .value |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:186:3:186:22 | ... .value |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:186:3:186:27 | ... = ... |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:186:26:186:27 | 42 |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:191:17:191:22 | Block |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:191:19:191:20 | 42 |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:192:5:192:5 | x |  | {EXTERNAL LOCATION} | Int |
+| accessors.swift:192:9:192:14 | answer |  | {EXTERNAL LOCATION} | Int |
 | basics.swift:1:5:1:16 | topLevelDecl |  | {EXTERNAL LOCATION} | Int |
 | basics.swift:1:25:1:25 | 0 |  | {EXTERNAL LOCATION} | Int |
 | basics.swift:2:1:2:1 | 0 |  | {EXTERNAL LOCATION} | Int |
@@ -1050,16 +1307,40 @@ inferType
 | closures.swift:38:9:38:10 | f2 | Args | {EXTERNAL LOCATION} | Tuple1 |
 | closures.swift:38:9:38:10 | f2 | Args.T0 | {EXTERNAL LOCATION} | Int |
 | closures.swift:38:9:38:10 | f2 | Return | {EXTERNAL LOCATION} | Int |
+| closures.swift:40:10:40:10 | f |  | {EXTERNAL LOCATION} | Function |
+| closures.swift:40:10:40:10 | f | Args | {EXTERNAL LOCATION} | Tuple1 |
+| closures.swift:40:10:40:10 | f | Args.T0 | {EXTERNAL LOCATION} | Int |
+| closures.swift:40:10:40:10 | f | Return | {EXTERNAL LOCATION} | Int |
+| closures.swift:40:37:43:5 | Block |  | {EXTERNAL LOCATION} | Function |
+| closures.swift:40:37:43:5 | Block | Args | {EXTERNAL LOCATION} | Tuple1 |
+| closures.swift:40:37:43:5 | Block | Args.T0 | {EXTERNAL LOCATION} | Int |
+| closures.swift:40:37:43:5 | Block | Return | {EXTERNAL LOCATION} | Int |
 | closures.swift:41:9:41:12 | self |  | closures.swift:31:1:50:1 | ClosureField |
 | closures.swift:41:9:41:14 | ... .f |  | {EXTERNAL LOCATION} | Function |
 | closures.swift:41:9:41:14 | ... .f | Args | {EXTERNAL LOCATION} | Tuple1 |
 | closures.swift:41:9:41:14 | ... .f | Args.T0 | {EXTERNAL LOCATION} | Int |
 | closures.swift:41:9:41:14 | ... .f | Return | {EXTERNAL LOCATION} | Int |
+| closures.swift:41:9:41:18 | ... = ... |  | {EXTERNAL LOCATION} | Function |
+| closures.swift:41:9:41:18 | ... = ... | Args | {EXTERNAL LOCATION} | Tuple1 |
+| closures.swift:41:9:41:18 | ... = ... | Args.T0 | {EXTERNAL LOCATION} | Int |
+| closures.swift:41:9:41:18 | ... = ... | Return | {EXTERNAL LOCATION} | Int |
+| closures.swift:41:18:41:18 | f |  | {EXTERNAL LOCATION} | Function |
+| closures.swift:41:18:41:18 | f | Args | {EXTERNAL LOCATION} | Tuple1 |
+| closures.swift:41:18:41:18 | f | Args.T0 | {EXTERNAL LOCATION} | Int |
+| closures.swift:41:18:41:18 | f | Return | {EXTERNAL LOCATION} | Int |
 | closures.swift:42:9:42:12 | self |  | closures.swift:31:1:50:1 | ClosureField |
 | closures.swift:42:9:42:15 | ... .f2 |  | {EXTERNAL LOCATION} | Function |
 | closures.swift:42:9:42:15 | ... .f2 | Args | {EXTERNAL LOCATION} | Tuple1 |
 | closures.swift:42:9:42:15 | ... .f2 | Args.T0 | {EXTERNAL LOCATION} | Int |
 | closures.swift:42:9:42:15 | ... .f2 | Return | {EXTERNAL LOCATION} | Int |
+| closures.swift:42:9:42:19 | ... = ... |  | {EXTERNAL LOCATION} | Function |
+| closures.swift:42:9:42:19 | ... = ... | Args | {EXTERNAL LOCATION} | Tuple1 |
+| closures.swift:42:9:42:19 | ... = ... | Args.T0 | {EXTERNAL LOCATION} | Int |
+| closures.swift:42:9:42:19 | ... = ... | Return | {EXTERNAL LOCATION} | Int |
+| closures.swift:42:19:42:19 | f |  | {EXTERNAL LOCATION} | Function |
+| closures.swift:42:19:42:19 | f | Args | {EXTERNAL LOCATION} | Tuple1 |
+| closures.swift:42:19:42:19 | f | Args.T0 | {EXTERNAL LOCATION} | Int |
+| closures.swift:42:19:42:19 | f | Return | {EXTERNAL LOCATION} | Int |
 | closures.swift:45:24:45:28 | value |  | {EXTERNAL LOCATION} | Int |
 | closures.swift:45:43:49:5 | Block |  | {EXTERNAL LOCATION} | Int |
 | closures.swift:47:9:47:12 | self |  | closures.swift:31:1:50:1 | ClosureField |
diff --git a/unified/ql/test/library-tests/type-inference/type-inference.ql b/unified/ql/test/library-tests/type-inference/type-inference.ql
index eab27d53c9ea..75eab8be8b30 100644
--- a/unified/ql/test/library-tests/type-inference/type-inference.ql
+++ b/unified/ql/test/library-tests/type-inference/type-inference.ql
@@ -20,11 +20,7 @@ query predicate inferType(AstNode n, TypePath path, Type t) {
 }
 
 module ResolveTest implements TestSig {
-  string getARelevantTag() {
-    result = "target"
-    or
-    result = "field"
-  }
+  string getARelevantTag() { result = ["target", "field", "accessor"] }
 
   predicate hasActualResult(Location location, string element, string tag, string value) {
     exists(Callable c, CallExpr ce |
@@ -42,6 +38,14 @@ module ResolveTest implements TestSig {
       nameBinding(field.getPattern(), value) and
       tag = "field"
     )
+    or
+    exists(AccessorDeclaration accessor, Expr access |
+      accessor = resolveAccessorAccess(access) and
+      location = access.getLocation() and
+      element = access.toString() and
+      callableName(accessor, value) and
+      tag = "accessor"
+    )
   }
 }
 

From 6263dc95825534496d436549bb31a573fc905193 Mon Sep 17 00:00:00 2001
From: Tom Hvitved <hvitved@github.com>
Date: Thu, 29 Oct 2026 13:43:17 +0100
Subject: [PATCH 3/3] Address review comments

---
 .../typeinference/internal/TypeInference.qll  | 10 ++++
 .../internal/dataflow/DataFlowPluginSwift.qll | 27 +++++++----
 .../internal/typeinference/TypeInference.qll  |  4 ++
 .../dataflow/accessors_instance.swift         |  2 +
 .../test/library-tests/dataflow/test.expected | 48 +++++++++----------
 5 files changed, 58 insertions(+), 33 deletions(-)

diff --git a/shared/typeinference/codeql/typeinference/internal/TypeInference.qll b/shared/typeinference/codeql/typeinference/internal/TypeInference.qll
index c69f1b1890e0..1bc9591607e8 100644
--- a/shared/typeinference/codeql/typeinference/internal/TypeInference.qll
+++ b/shared/typeinference/codeql/typeinference/internal/TypeInference.qll
@@ -3683,6 +3683,16 @@ module Make1<LocationSig Location, InputSig1<Location> Input1> {
       pragma[nomagic]
       Type inferType(AstNode n) { result = inferType(n, TypePath::nil()) }
 
+      /** Gets the unique non-pseudo type inferred at `path` for `n`, if any. */
+      Type inferTypeUnique(AstNode n, TypePath path) {
+        result = unique(Type t | t = inferType(n, path) and not t instanceof PseudoType | t)
+      }
+
+      /**
+       * Gets the unique non-pseudo type inferred at the root for `n`, if any.
+       */
+      Type inferTypeUnique(AstNode n) { result = inferTypeUnique(n, TypePath::nil()) }
+
       /**
        * The cached stage of this module.
        *
diff --git a/unified/ql/lib/codeql/unified/internal/dataflow/DataFlowPluginSwift.qll b/unified/ql/lib/codeql/unified/internal/dataflow/DataFlowPluginSwift.qll
index b71fbf16120c..f845a5f20f3c 100644
--- a/unified/ql/lib/codeql/unified/internal/dataflow/DataFlowPluginSwift.qll
+++ b/unified/ql/lib/codeql/unified/internal/dataflow/DataFlowPluginSwift.qll
@@ -7,6 +7,11 @@ private import AllDataFlow
 private import codeql.unified.internal.ExprPositions
 private import codeql.unified.internal.typeinference.TypeInference as T
 
+private predicate isReferenceType(T::Type t) {
+  // todo: type parameters with type constraints
+  t.asClass().hasModifier(["actor", "class"])
+}
+
 private class SwiftDataFlowPlugin extends DataFlowPlugin {
   // Note: For now we assume all code is Swift, but in the future we must restrict these rules to Swift-files
   override predicate bypassContentSet(ContentSet contents) {
@@ -16,9 +21,9 @@ private class SwiftDataFlowPlugin extends DataFlowPlugin {
   // Swift writes back mutated values of computed value-type properties via their setter
   bindingset[expr]
   override predicate mayWriteBackViaSetterCall(Expr expr) {
-    isInWriteBackPosition(expr) and
-    // conservative value-type check
-    not forex(T::Type t | t = T::inferType(expr) | t.asClass().hasModifier("class"))
+    exists(boolean direct | isInWriteBackPosition(expr, direct) |
+      if direct = false then not isReferenceType(T::inferTypeUnique(expr)) else any()
+    )
   }
 
   override predicate exprStep(Expr expr1, Expr expr2, boolean mustFlow) {
@@ -101,25 +106,29 @@ private class SwiftDataFlowPlugin extends DataFlowPlugin {
  * Holds if `expr` is target of an assignment or 'inout' argument,
  * or the base of such an expression, e.g. `x` in `x.f1.f2 = foo()`
  */
-private predicate isInWriteBackPosition(Expr expr) {
-  isInAssignmentContext(expr, _)
+private predicate isInWriteBackPosition(Expr expr, boolean direct) {
+  isInAssignmentContext(expr, _) and
+  direct = false
   or
   // Arguments to an 'inout' parameter must be prefixed with '&'
   exists(UnaryExpr unary |
     unary.getOperator().(PrefixOperator).getValue() = "&" and
     unary.getOperand() = expr
     // TODO: support custom operators with an 'inout' parameter, which lack the '&' indicator
-  )
+  ) and
+  direct = true
   or
   // The receiver of a call to a 'mutating' function counts as an 'inout' argument
   exists(CallExpr call, Callable target |
     target = T::resolveCallTarget(call) and
     target.hasModifier("mutating") and
     expr = call.getCallee().(MemberAccessExpr).getBase()
-  )
+  ) and
+  direct = true
   or
   exists(MemberAccessExpr member |
-    isInWriteBackPosition(member) and
-    expr = member.getBase()
+    isInWriteBackPosition(member, _) and
+    expr = member.getBase() and
+    direct = false
   )
 }
diff --git a/unified/ql/lib/codeql/unified/internal/typeinference/TypeInference.qll b/unified/ql/lib/codeql/unified/internal/typeinference/TypeInference.qll
index 85a1c0281cfb..2dd7596e29cc 100644
--- a/unified/ql/lib/codeql/unified/internal/typeinference/TypeInference.qll
+++ b/unified/ql/lib/codeql/unified/internal/typeinference/TypeInference.qll
@@ -856,6 +856,10 @@ predicate inferType = M3::inferType/1;
 
 predicate inferType = M3::inferType/2;
 
+predicate inferTypeUnique = M3::inferTypeUnique/1;
+
+predicate inferTypeUnique = M3::inferTypeUnique/2;
+
 predicate inferTypeCertain = M3::inferTypeCertain/2;
 
 module Consistency = M3::Consistency;
diff --git a/unified/ql/test/library-tests/dataflow/accessors_instance.swift b/unified/ql/test/library-tests/dataflow/accessors_instance.swift
index b9daa47f45b5..6c76138c5506 100644
--- a/unified/ql/test/library-tests/dataflow/accessors_instance.swift
+++ b/unified/ql/test/library-tests/dataflow/accessors_instance.swift
@@ -139,7 +139,9 @@ func t11() {
         }
     }
     let c = C()
+    // `p` has value type, so this calls `p`'s setter
     c.p.0 = source("t11.1")
+    // `q` has reference type, so this calls `q`'s getter followed by `p`'s setter
     c.q.p = (source("t11.2"), source("t11.3"))
 }
 
diff --git a/unified/ql/test/library-tests/dataflow/test.expected b/unified/ql/test/library-tests/dataflow/test.expected
index 2af1a83d8f56..40fb146a8fde 100644
--- a/unified/ql/test/library-tests/dataflow/test.expected
+++ b/unified/ql/test/library-tests/dataflow/test.expected
@@ -32,16 +32,16 @@ edges
 | accessors_instance.swift:119:13:119:17 | field | accessors_instance.swift:125:18:125:22 | field | provenance |  |
 | accessors_instance.swift:119:21:119:35 | source(...) | accessors_instance.swift:119:13:119:17 | field | provenance |  |
 | accessors_instance.swift:134:24:134:31 | newValue [0] | accessors_instance.swift:134:24:134:33 | ... .0 | provenance |  |
-| accessors_instance.swift:142:5:142:7 | [post] ... .p [0] | accessors_instance.swift:134:24:134:31 | newValue [0] | provenance |  |
-| accessors_instance.swift:142:5:142:9 | ... .0 | accessors_instance.swift:142:5:142:7 | [post] ... .p [0] | provenance |  |
-| accessors_instance.swift:142:13:142:27 | source(...) | accessors_instance.swift:142:5:142:9 | ... .0 | provenance |  |
-| accessors_instance.swift:143:5:143:9 | ... .p [0] | accessors_instance.swift:134:24:134:31 | newValue [0] | provenance |  |
-| accessors_instance.swift:143:13:143:46 | TupleExpr [0] | accessors_instance.swift:143:5:143:9 | ... .p [0] | provenance |  |
-| accessors_instance.swift:143:14:143:28 | source(...) | accessors_instance.swift:143:13:143:46 | TupleExpr [0] | provenance |  |
-| accessors_instance.swift:149:34:149:38 | field | accessors_instance.swift:158:5:158:7 | [post] ... .s [field] | provenance |  |
-| accessors_instance.swift:149:42:149:56 | source(...) | accessors_instance.swift:149:34:149:38 | field | provenance |  |
-| accessors_instance.swift:154:24:154:31 | newValue [field] | accessors_instance.swift:154:24:154:37 | ... .field | provenance |  |
-| accessors_instance.swift:158:5:158:7 | [post] ... .s [field] | accessors_instance.swift:154:24:154:31 | newValue [field] | provenance |  |
+| accessors_instance.swift:143:5:143:7 | [post] ... .p [0] | accessors_instance.swift:134:24:134:31 | newValue [0] | provenance |  |
+| accessors_instance.swift:143:5:143:9 | ... .0 | accessors_instance.swift:143:5:143:7 | [post] ... .p [0] | provenance |  |
+| accessors_instance.swift:143:13:143:27 | source(...) | accessors_instance.swift:143:5:143:9 | ... .0 | provenance |  |
+| accessors_instance.swift:145:5:145:9 | ... .p [0] | accessors_instance.swift:134:24:134:31 | newValue [0] | provenance |  |
+| accessors_instance.swift:145:13:145:46 | TupleExpr [0] | accessors_instance.swift:145:5:145:9 | ... .p [0] | provenance |  |
+| accessors_instance.swift:145:14:145:28 | source(...) | accessors_instance.swift:145:13:145:46 | TupleExpr [0] | provenance |  |
+| accessors_instance.swift:151:34:151:38 | field | accessors_instance.swift:160:5:160:7 | [post] ... .s [field] | provenance |  |
+| accessors_instance.swift:151:42:151:56 | source(...) | accessors_instance.swift:151:34:151:38 | field | provenance |  |
+| accessors_instance.swift:156:24:156:31 | newValue [field] | accessors_instance.swift:156:24:156:37 | ... .field | provenance |  |
+| accessors_instance.swift:160:5:160:7 | [post] ... .s [field] | accessors_instance.swift:156:24:156:31 | newValue [field] | provenance |  |
 | accessors_local.swift:7:21:7:34 | source(...) | accessors_local.swift:8:10:8:10 | x | provenance |  |
 | accessors_local.swift:15:15:15:28 | source(...) | accessors_local.swift:17:10:17:10 | x | provenance |  |
 | accessors_local.swift:22:15:22:28 | source(...) | accessors_local.swift:25:10:25:10 | x | provenance |  |
@@ -569,17 +569,17 @@ nodes
 | accessors_instance.swift:125:18:125:22 | field | semmle.label | field |
 | accessors_instance.swift:134:24:134:31 | newValue [0] | semmle.label | newValue [0] |
 | accessors_instance.swift:134:24:134:33 | ... .0 | semmle.label | ... .0 |
-| accessors_instance.swift:142:5:142:7 | [post] ... .p [0] | semmle.label | [post] ... .p [0] |
-| accessors_instance.swift:142:5:142:9 | ... .0 | semmle.label | ... .0 |
-| accessors_instance.swift:142:13:142:27 | source(...) | semmle.label | source(...) |
-| accessors_instance.swift:143:5:143:9 | ... .p [0] | semmle.label | ... .p [0] |
-| accessors_instance.swift:143:13:143:46 | TupleExpr [0] | semmle.label | TupleExpr [0] |
-| accessors_instance.swift:143:14:143:28 | source(...) | semmle.label | source(...) |
-| accessors_instance.swift:149:34:149:38 | field | semmle.label | field |
-| accessors_instance.swift:149:42:149:56 | source(...) | semmle.label | source(...) |
-| accessors_instance.swift:154:24:154:31 | newValue [field] | semmle.label | newValue [field] |
-| accessors_instance.swift:154:24:154:37 | ... .field | semmle.label | ... .field |
-| accessors_instance.swift:158:5:158:7 | [post] ... .s [field] | semmle.label | [post] ... .s [field] |
+| accessors_instance.swift:143:5:143:7 | [post] ... .p [0] | semmle.label | [post] ... .p [0] |
+| accessors_instance.swift:143:5:143:9 | ... .0 | semmle.label | ... .0 |
+| accessors_instance.swift:143:13:143:27 | source(...) | semmle.label | source(...) |
+| accessors_instance.swift:145:5:145:9 | ... .p [0] | semmle.label | ... .p [0] |
+| accessors_instance.swift:145:13:145:46 | TupleExpr [0] | semmle.label | TupleExpr [0] |
+| accessors_instance.swift:145:14:145:28 | source(...) | semmle.label | source(...) |
+| accessors_instance.swift:151:34:151:38 | field | semmle.label | field |
+| accessors_instance.swift:151:42:151:56 | source(...) | semmle.label | source(...) |
+| accessors_instance.swift:156:24:156:31 | newValue [field] | semmle.label | newValue [field] |
+| accessors_instance.swift:156:24:156:37 | ... .field | semmle.label | ... .field |
+| accessors_instance.swift:160:5:160:7 | [post] ... .s [field] | semmle.label | [post] ... .s [field] |
 | accessors_local.swift:7:21:7:34 | source(...) | semmle.label | source(...) |
 | accessors_local.swift:8:10:8:10 | x | semmle.label | x |
 | accessors_local.swift:15:15:15:28 | source(...) | semmle.label | source(...) |
@@ -1215,9 +1215,9 @@ testFailures
 | accessors_instance.swift:99:10:99:21 | ... .otherField | accessors_instance.swift:97:15:97:28 | source(...) | accessors_instance.swift:99:10:99:21 | ... .otherField | $@ | accessors_instance.swift:97:15:97:28 | source(...) | source(...) |
 | accessors_instance.swift:112:10:112:16 | ... .field | accessors_instance.swift:106:21:106:34 | source(...) | accessors_instance.swift:112:10:112:16 | ... .field | $@ | accessors_instance.swift:106:21:106:34 | source(...) | source(...) |
 | accessors_instance.swift:125:18:125:22 | field | accessors_instance.swift:119:21:119:35 | source(...) | accessors_instance.swift:125:18:125:22 | field | $@ | accessors_instance.swift:119:21:119:35 | source(...) | source(...) |
-| accessors_instance.swift:134:24:134:33 | ... .0 | accessors_instance.swift:142:13:142:27 | source(...) | accessors_instance.swift:134:24:134:33 | ... .0 | $@ | accessors_instance.swift:142:13:142:27 | source(...) | source(...) |
-| accessors_instance.swift:134:24:134:33 | ... .0 | accessors_instance.swift:143:14:143:28 | source(...) | accessors_instance.swift:134:24:134:33 | ... .0 | $@ | accessors_instance.swift:143:14:143:28 | source(...) | source(...) |
-| accessors_instance.swift:154:24:154:37 | ... .field | accessors_instance.swift:149:42:149:56 | source(...) | accessors_instance.swift:154:24:154:37 | ... .field | $@ | accessors_instance.swift:149:42:149:56 | source(...) | source(...) |
+| accessors_instance.swift:134:24:134:33 | ... .0 | accessors_instance.swift:143:13:143:27 | source(...) | accessors_instance.swift:134:24:134:33 | ... .0 | $@ | accessors_instance.swift:143:13:143:27 | source(...) | source(...) |
+| accessors_instance.swift:134:24:134:33 | ... .0 | accessors_instance.swift:145:14:145:28 | source(...) | accessors_instance.swift:134:24:134:33 | ... .0 | $@ | accessors_instance.swift:145:14:145:28 | source(...) | source(...) |
+| accessors_instance.swift:156:24:156:37 | ... .field | accessors_instance.swift:151:42:151:56 | source(...) | accessors_instance.swift:156:24:156:37 | ... .field | $@ | accessors_instance.swift:151:42:151:56 | source(...) | source(...) |
 | accessors_local.swift:8:10:8:10 | x | accessors_local.swift:7:21:7:34 | source(...) | accessors_local.swift:8:10:8:10 | x | $@ | accessors_local.swift:7:21:7:34 | source(...) | source(...) |
 | accessors_local.swift:17:10:17:10 | x | accessors_local.swift:15:15:15:28 | source(...) | accessors_local.swift:17:10:17:10 | x | $@ | accessors_local.swift:15:15:15:28 | source(...) | source(...) |
 | accessors_local.swift:25:10:25:10 | x | accessors_local.swift:22:15:22:28 | source(...) | accessors_local.swift:25:10:25:10 | x | $@ | accessors_local.swift:22:15:22:28 | source(...) | source(...) |