Improve evaluation of typealiases (#1796)

This simplifies the resolution of names in typealias constraints.
This removes the existing logic around swapping out the frame's
owner/receiver, and instead favors resolving the variable at parse time.

* During variable resolution, create read variable nodes that read off of
  a receiver node
* Introduce `GetTypeAliasModuleNode` that provides the typealias's
  enclosing module
* Inject the enclosing module during typealias instantiation

pkl-core/src/main/java/org/pkl/core/ast/builder/AstBuilder.java

@@ -112,14 +112,17 @@ import org.pkl.core.ast.expression.literal.TrueLiteralNode;
 import org.pkl.core.ast.expression.member.InferParentWithinMethodNode;
 import org.pkl.core.ast.expression.member.InferParentWithinObjectMethodNode;
 import org.pkl.core.ast.expression.member.InferParentWithinPropertyNodeGen;
-import org.pkl.core.ast.expression.member.InvokeClassMethodNode;
+import org.pkl.core.ast.expression.member.InvokeLexicalClassMethodNode;
+import org.pkl.core.ast.expression.member.InvokeLexicalObjectMethodNode;
 import org.pkl.core.ast.expression.member.InvokeMethodDirectNode;
 import org.pkl.core.ast.expression.member.InvokeMethodVirtualNodeGen;
-import org.pkl.core.ast.expression.member.InvokeObjectMethodNode;
+import org.pkl.core.ast.expression.member.InvokeQualifiedClassMethodNode;
+import org.pkl.core.ast.expression.member.InvokeQualifiedObjectMethodNode;
 import org.pkl.core.ast.expression.member.InvokeSuperMethodNodeGen;
 import org.pkl.core.ast.expression.member.ReadAmbiguousLocalityPropertyNode;
-import org.pkl.core.ast.expression.member.ReadLocalPropertyNode;
+import org.pkl.core.ast.expression.member.ReadLexicalLocalPropertyNode;
 import org.pkl.core.ast.expression.member.ReadPropertyNodeGen;
+import org.pkl.core.ast.expression.member.ReadQualifiedLocalPropertyNode;
 import org.pkl.core.ast.expression.member.ReadSuperEntryNode;
 import org.pkl.core.ast.expression.member.ReadSuperPropertyNode;
 import org.pkl.core.ast.expression.primary.ExecuteCustomThisWithRootNode;
@@ -128,6 +131,7 @@ import org.pkl.core.ast.expression.primary.GetMemberKeyNode;
 import org.pkl.core.ast.expression.primary.GetModuleNode;
 import org.pkl.core.ast.expression.primary.GetOwnerNode;
 import org.pkl.core.ast.expression.primary.GetReceiverNode;
+import org.pkl.core.ast.expression.primary.GetTypeAliasModuleNode;
 import org.pkl.core.ast.expression.primary.OuterNode;
 import org.pkl.core.ast.expression.primary.ThisNode;
 import org.pkl.core.ast.expression.ternary.IfElseNode;
@@ -526,7 +530,7 @@ public class AstBuilder extends AbstractAstBuilder<Object> {
   }
 
   @Override
-  public GetModuleNode visitModuleExpr(ModuleExpr expr) {
+  public ExpressionNode visitModuleExpr(ModuleExpr expr) {
     var currentScope = symbolTable.getCurrentScope();
     // cannot use unqualified `module` in a const context
     if (currentScope.getConstLevel().isConst() && !(expr.parent() instanceof QualifiedAccessExpr)) {
@@ -549,7 +553,9 @@ public class AstBuilder extends AbstractAstBuilder<Object> {
           .withSourceSection(createSourceSection(expr))
           .build();
     }
-    return new GetModuleNode(createSourceSection(expr));
+    return symbolTable.isInTypeAliasScope
+        ? new GetTypeAliasModuleNode(createSourceSection(expr))
+        : new GetModuleNode(createSourceSection(expr));
   }
 
   @Override
@@ -687,12 +693,30 @@ public class AstBuilder extends AbstractAstBuilder<Object> {
             case MODULE -> p.isModuleScope();
             case ALL -> p.levelsUp() > constDepth;
           };
+      // Assumption: typealiases can only be declared on the module.
+      // If we ever allow typealiases in classes, this code needs to change.
+      if (symbolTable.isInTypeAliasScope && p.isModuleScope()) {
+        var getModuleNode = new GetTypeAliasModuleNode(sourceSection);
+        if (p.isLocal()) {
+          return new ReadQualifiedLocalPropertyNode(
+              sourceSection,
+              org.pkl.core.runtime.Identifier.localProperty(name),
+              needsConst,
+              getModuleNode);
+        }
+        return ReadPropertyNodeGen.create(
+            sourceSection,
+            org.pkl.core.runtime.Identifier.get(name),
+            MemberLookupMode.IMPLICIT_LEXICAL,
+            needsConst,
+            getModuleNode);
+      }
       if (p.isAmbiguousLocality()) {
         return new ReadAmbiguousLocalityPropertyNode(
             sourceSection, org.pkl.core.runtime.Identifier.get(name), p.levelsUp(), needsConst);
       }
       if (p.isLocal()) {
-        return new ReadLocalPropertyNode(
+        return new ReadLexicalLocalPropertyNode(
             sourceSection,
             org.pkl.core.runtime.Identifier.localProperty(name),
             p.levelsUp(),
@@ -769,11 +793,34 @@ public class AstBuilder extends AbstractAstBuilder<Object> {
             case MODULE -> method.isModuleScope();
             case ALL -> method.levelsUp() > constDepth;
           };
+      // Assumption: typealiases can only be declared on the module.
+      // If we ever allow typealiases in classes, this code needs to change.
+      if (symbolTable.isInTypeAliasScope && method.isModuleScope()) {
+        var getModuleNode = new GetTypeAliasModuleNode(sourceSection);
+        if (method.isObjectMethod()) {
+          return new InvokeQualifiedObjectMethodNode(
+              sourceSection, identifier, args, needsConst, getModuleNode);
+        }
+        if (method.isOnClosedClass() || method.isLocal() || method.isExternal()) {
+          return new InvokeQualifiedClassMethodNode(
+              sourceSection, identifier, args, needsConst, getModuleNode);
+        }
+        return InvokeMethodVirtualNodeGen.create(
+            sourceSection,
+            identifier,
+            args,
+            MemberLookupMode.IMPLICIT_LEXICAL,
+            needsConst,
+            getModuleNode,
+            GetClassNodeGen.create(null));
+      }
       if (method.isObjectMethod()) {
-        return new InvokeObjectMethodNode(sourceSection, identifier, levelsUp, args, needsConst);
+        return new InvokeLexicalObjectMethodNode(
+            sourceSection, identifier, levelsUp, args, needsConst);
       }
       if (method.isOnClosedClass() || method.isLocal() || method.isExternal()) {
-        return new InvokeClassMethodNode(sourceSection, identifier, levelsUp, args, needsConst);
+        return new InvokeLexicalClassMethodNode(
+            sourceSection, identifier, levelsUp, args, needsConst);
       }
       return InvokeMethodVirtualNodeGen.create(
           sourceSection,

pkl-core/src/main/java/org/pkl/core/ast/builder/SymbolTable.java

@@ -47,6 +47,8 @@ import org.pkl.parser.Lexer;
 public final class SymbolTable {
 
   private Scope currentScope;
+  // consider having each scope keep track of this individually rather than set on SymbolTable.
+  public boolean isInTypeAliasScope;
 
   public SymbolTable(ModuleInfo moduleInfo, boolean isBaseModule) {
     currentScope = new ModuleScope(moduleInfo, isBaseModule);
@@ -85,14 +87,19 @@ public final class SymbolTable {
       Identifier name,
       List<TypeParameter> typeParameters,
       Function<TypeAliasScope, ObjectMember> nodeFactory) {
-    return doEnter(
-        new TypeAliasScope(
-            currentScope,
-            name,
-            toQualifiedName(name),
-            new FrameDescriptorBuilder(),
-            typeParameters),
-        nodeFactory);
+    try {
+      this.isInTypeAliasScope = true;
+      return doEnter(
+          new TypeAliasScope(
+              currentScope,
+              name,
+              toQualifiedName(name),
+              new FrameDescriptorBuilder(),
+              typeParameters),
+          nodeFactory);
+    } finally {
+      this.isInTypeAliasScope = false;
+    }
   }
 
   public <T> T enterMethod(

pkl-core/src/main/java/org/pkl/core/ast/expression/member/AbstractInvokeLexicalMethodNode.java

@@ -0,0 +1,45 @@
+/*
+ * Copyright © 2026 Apple Inc. and the Pkl project authors. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.pkl.core.ast.expression.member;
+
+import com.oracle.truffle.api.frame.VirtualFrame;
+import com.oracle.truffle.api.source.SourceSection;
+import org.pkl.core.ast.ExpressionNode;
+import org.pkl.core.runtime.Identifier;
+import org.pkl.core.runtime.VmUtils;
+
+public abstract sealed class AbstractInvokeLexicalMethodNode extends AbstractInvokeMethodNode
+    permits InvokeLexicalClassMethodNode, InvokeLexicalObjectMethodNode {
+  private final int levelsUp;
+
+  public AbstractInvokeLexicalMethodNode(
+      SourceSection sourceSection,
+      Identifier methodName,
+      int levelsUp,
+      ExpressionNode[] argumentNodes,
+      boolean needsConst) {
+    super(sourceSection, methodName, argumentNodes, needsConst);
+    this.levelsUp = levelsUp;
+  }
+
+  @Override
+  public final Object executeGeneric(VirtualFrame frame) {
+    var capturedFrame = VmUtils.getFrame(frame, levelsUp);
+    var owner = VmUtils.getOwner(capturedFrame);
+    var receiver = VmUtils.getReceiver(capturedFrame);
+    return invoke(frame, owner, receiver);
+  }
+}

pkl-core/src/main/java/org/pkl/core/ast/expression/member/AbstractInvokeMethodNode.java

@@ -26,40 +26,40 @@ import org.jspecify.annotations.Nullable;
 import org.pkl.core.ast.ExpressionNode;
 import org.pkl.core.runtime.Identifier;
 import org.pkl.core.runtime.VmObjectLike;
-import org.pkl.core.runtime.VmUtils;
 
-public abstract sealed class AbstractInvokeMethodLexicalNode extends ExpressionNode
-    permits InvokeObjectMethodNode, InvokeClassMethodNode {
+/**
+ * A non-virtual (statically dispatched) method call.
+ *
+ * <p>Subclasses differ only in how they obtain the {@code owner}/{@code receiver} that the method
+ * is invoked on: either by walking the frame chain ({@link InvokeLexicalClassMethodNode}, {@link
+ * InvokeLexicalObjectMethodNode}), or off of an explicit receiver expression ({@link
+ * InvokeQualifiedClassMethodNode}, {@link InvokeQualifiedObjectMethodNode}).
+ */
+public abstract sealed class AbstractInvokeMethodNode extends ExpressionNode
+    permits AbstractInvokeQualifiedMethodNode, AbstractInvokeLexicalMethodNode {
 
   protected final Identifier methodName;
-  protected final int levelsUp;
   private final boolean needsConst;
   @Children private ExpressionNode[] argumentNodes;
   @Child private @Nullable DirectCallNode callNode;
   @CompilationFinal protected boolean isConstChecked;
 
-  protected AbstractInvokeMethodLexicalNode(
+  protected AbstractInvokeMethodNode(
       SourceSection sourceSection,
       Identifier methodName,
-      int levelsUp,
       ExpressionNode[] argumentNodes,
       boolean needsConst) {
     super(sourceSection);
     this.methodName = methodName;
-    this.levelsUp = levelsUp;
     this.argumentNodes = argumentNodes;
     this.needsConst = needsConst;
     this.isConstChecked = false;
   }
 
-  @Override
   @ExplodeLoop
-  public final Object executeGeneric(VirtualFrame frame) {
-    var args = new Object[2 + argumentNodes.length];
-    var capturedFrame = VmUtils.getFrame(frame, levelsUp);
-    var owner = VmUtils.getOwner(capturedFrame);
-    var receiver = VmUtils.getReceiver(capturedFrame);
+  protected final Object invoke(VirtualFrame frame, VmObjectLike owner, Object receiver) {
     checkConst(owner);
+    var args = new Object[2 + argumentNodes.length];
     args[0] = receiver;
     args[1] = owner;
     for (var i = 0; i < argumentNodes.length; i++) {
@@ -81,10 +81,6 @@ public abstract sealed class AbstractInvokeMethodLexicalNode extends ExpressionN
 
   protected abstract void doCheckConst(VmObjectLike owner);
 
-  protected final VmObjectLike getOwner(VirtualFrame frame) {
-    return VmUtils.getOwner(frame, levelsUp);
-  }
-
   protected DirectCallNode getCallNode(VmObjectLike owner) {
     if (callNode == null) {
       CompilerDirectives.transferToInterpreterAndInvalidate();

pkl-core/src/main/java/org/pkl/core/ast/expression/member/AbstractInvokeQualifiedMethodNode.java

@@ -0,0 +1,43 @@
+/*
+ * Copyright © 2026 Apple Inc. and the Pkl project authors. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.pkl.core.ast.expression.member;
+
+import com.oracle.truffle.api.frame.VirtualFrame;
+import com.oracle.truffle.api.source.SourceSection;
+import org.pkl.core.ast.ExpressionNode;
+import org.pkl.core.runtime.Identifier;
+import org.pkl.core.runtime.VmTyped;
+
+public abstract sealed class AbstractInvokeQualifiedMethodNode extends AbstractInvokeMethodNode
+    permits InvokeQualifiedClassMethodNode, InvokeQualifiedObjectMethodNode {
+  @Child private ExpressionNode getReceiverNode;
+
+  protected AbstractInvokeQualifiedMethodNode(
+      SourceSection sourceSection,
+      Identifier methodName,
+      ExpressionNode[] argumentNodes,
+      boolean needsConst,
+      ExpressionNode getReceiverNode) {
+    super(sourceSection, methodName, argumentNodes, needsConst);
+    this.getReceiverNode = getReceiverNode;
+  }
+
+  @Override
+  public final Object executeGeneric(VirtualFrame frame) {
+    var receiver = (VmTyped) getReceiverNode.executeGeneric(frame);
+    return invoke(frame, receiver, receiver);
+  }
+}

pkl-core/src/main/java/org/pkl/core/ast/expression/member/AbstractReadLocalPropertyNode.java

@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2026 Apple Inc. and the Pkl project authors. All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -15,69 +15,38 @@
  */
 package org.pkl.core.ast.expression.member;
 
-import com.oracle.truffle.api.CompilerAsserts;
 import com.oracle.truffle.api.CompilerDirectives;
 import com.oracle.truffle.api.CompilerDirectives.CompilationFinal;
-import com.oracle.truffle.api.frame.VirtualFrame;
 import com.oracle.truffle.api.nodes.DirectCallNode;
-import com.oracle.truffle.api.nodes.ExplodeLoop;
 import com.oracle.truffle.api.source.SourceSection;
 import org.jspecify.annotations.Nullable;
-import org.pkl.core.PklBugException;
 import org.pkl.core.ast.ExpressionNode;
 import org.pkl.core.ast.member.ObjectMember;
 import org.pkl.core.runtime.Identifier;
 import org.pkl.core.runtime.VmObjectLike;
-import org.pkl.core.runtime.VmUtils;
 
-/** Reads a local non-constant property that is known to exist in the lexical scope of this node. */
-public final class ReadLocalPropertyNode extends ExpressionNode {
+public abstract class AbstractReadLocalPropertyNode extends ExpressionNode {
+
   private final Identifier name;
-  private final int levelsUp;
   private final boolean needsConst;
   @Child private @Nullable DirectCallNode callNode;
   @CompilationFinal @Nullable private ObjectMember property;
 
-  public ReadLocalPropertyNode(
-      SourceSection sourceSection, Identifier name, int levelsUp, boolean needsConst) {
-
+  public AbstractReadLocalPropertyNode(
+      SourceSection sourceSection, Identifier name, boolean needsConst) {
     super(sourceSection);
-    CompilerAsserts.neverPartOfCompilation();
-
     this.name = name;
-    this.levelsUp = levelsUp;
     this.needsConst = needsConst;
   }
 
-  @Override
-  @ExplodeLoop
-  public Object executeGeneric(VirtualFrame frame) {
-    var owner = VmUtils.getOwner(frame, levelsUp);
-    var property = getProperty(owner);
-    var constantValue = property.getConstantValue();
-    if (constantValue != null) {
-      return constantValue;
-    }
-
-    var receiver = (VmObjectLike) VmUtils.getReceiver(frame, levelsUp);
-    var result = receiver.getCachedValue(property);
-
-    if (result == null) {
-      result = getCallNode(property).call(receiver, owner, property.getName());
-      receiver.setCachedValue(property, result);
-    }
-
-    return result;
-  }
-
-  private ObjectMember getProperty(VmObjectLike owner) {
+  protected ObjectMember getProperty(VmObjectLike owner) {
     if (property == null) {
       CompilerDirectives.transferToInterpreterAndInvalidate();
       property = owner.getMember(name);
       if (property == null) {
         // should never happen
         CompilerDirectives.transferToInterpreter();
-        throw new PklBugException("Couldn't find local variable `" + name + "`.");
+        throw exceptionBuilder().bug("Couldn't find local variable `" + name + "`.").build();
       }
       if (needsConst && !property.isConst()) {
         throw exceptionBuilder().evalError("propertyMustBeConst", name.toString()).build();
@@ -86,7 +55,7 @@ public final class ReadLocalPropertyNode extends ExpressionNode {
     return property;
   }
 
-  public DirectCallNode getCallNode(ObjectMember property) {
+  protected DirectCallNode getCallNode(ObjectMember property) {
     if (callNode == null) {
       CompilerDirectives.transferToInterpreterAndInvalidate();
       callNode = DirectCallNode.create(property.getCallTarget());

pkl-core/src/main/java/org/pkl/core/ast/expression/member/InvokeLexicalClassMethodNode.java

@@ -24,11 +24,9 @@ import org.pkl.core.runtime.VmObjectLike;
 /**
  * A non-virtual call of closed methods (methods whose enclosing class/module is not open nor
  * abstract, and is lexically scoped).
- *
- * <p>For local methods, use {@link InvokeObjectMethodNode}.
  */
-public final class InvokeClassMethodNode extends AbstractInvokeMethodLexicalNode {
-  public InvokeClassMethodNode(
+public final class InvokeLexicalClassMethodNode extends AbstractInvokeLexicalMethodNode {
+  public InvokeLexicalClassMethodNode(
       SourceSection sourceSection,
       Identifier methodName,
       int levelsUp,

pkl-core/src/main/java/org/pkl/core/ast/expression/member/InvokeLexicalObjectMethodNode.java

@@ -22,9 +22,9 @@ import org.pkl.core.ast.VmModifier;
 import org.pkl.core.runtime.Identifier;
 import org.pkl.core.runtime.VmObjectLike;
 
-/** A non-virtual call of a local method. */
-public final class InvokeObjectMethodNode extends AbstractInvokeMethodLexicalNode {
-  public InvokeObjectMethodNode(
+/** A non-virtual call of an object method that is lexically scoped. */
+public final class InvokeLexicalObjectMethodNode extends AbstractInvokeLexicalMethodNode {
+  public InvokeLexicalObjectMethodNode(
       SourceSection sourceSection,
       Identifier methodName,
       int levelsUp,
@@ -33,6 +33,7 @@ public final class InvokeObjectMethodNode extends AbstractInvokeMethodLexicalNod
     super(sourceSection, methodName, levelsUp, argumentNodes, needsConst);
   }
 
+  @Override
   protected void doCheckConst(VmObjectLike owner) {
     var member = owner.getMember(methodName);
     assert member != null;

pkl-core/src/main/java/org/pkl/core/ast/expression/member/InvokeQualifiedClassMethodNode.java

@@ -0,0 +1,50 @@
+/*
+ * Copyright © 2026 Apple Inc. and the Pkl project authors. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.pkl.core.ast.expression.member;
+
+import com.oracle.truffle.api.CallTarget;
+import com.oracle.truffle.api.source.SourceSection;
+import org.pkl.core.ast.ExpressionNode;
+import org.pkl.core.runtime.Identifier;
+import org.pkl.core.runtime.VmObjectLike;
+
+/** A non-virtual call of a closed class method, invoked off of an explicit receiver. */
+public final class InvokeQualifiedClassMethodNode extends AbstractInvokeQualifiedMethodNode {
+  public InvokeQualifiedClassMethodNode(
+      SourceSection sourceSection,
+      Identifier methodName,
+      ExpressionNode[] argumentNodes,
+      boolean needsConst,
+      ExpressionNode getReceiverNode) {
+    super(sourceSection, methodName, argumentNodes, needsConst, getReceiverNode);
+  }
+
+  @Override
+  protected void doCheckConst(VmObjectLike owner) {
+    var method = owner.getVmClass().getDeclaredMethod(methodName);
+    assert method != null;
+    if (!method.isConst()) {
+      throw exceptionBuilder().evalError("methodMustBeConst", methodName).build();
+    }
+  }
+
+  @Override
+  protected CallTarget getCallTarget(VmObjectLike owner) {
+    var method = owner.getVmClass().getDeclaredMethod(methodName);
+    assert method != null;
+    return method.getCallTarget(getSourceSection());
+  }
+}

pkl-core/src/main/java/org/pkl/core/ast/expression/member/InvokeQualifiedObjectMethodNode.java

@@ -0,0 +1,51 @@
+/*
+ * Copyright © 2026 Apple Inc. and the Pkl project authors. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.pkl.core.ast.expression.member;
+
+import com.oracle.truffle.api.CallTarget;
+import com.oracle.truffle.api.source.SourceSection;
+import org.pkl.core.ast.ExpressionNode;
+import org.pkl.core.ast.VmModifier;
+import org.pkl.core.runtime.Identifier;
+import org.pkl.core.runtime.VmObjectLike;
+
+/** A non-virtual call of an object method, invoked off of an explicit receiver. */
+public final class InvokeQualifiedObjectMethodNode extends AbstractInvokeQualifiedMethodNode {
+  public InvokeQualifiedObjectMethodNode(
+      SourceSection sourceSection,
+      Identifier methodName,
+      ExpressionNode[] argumentNodes,
+      boolean needsConst,
+      ExpressionNode getReceiverNode) {
+    super(sourceSection, methodName, argumentNodes, needsConst, getReceiverNode);
+  }
+
+  @Override
+  protected void doCheckConst(VmObjectLike owner) {
+    var member = owner.getMember(methodName);
+    assert member != null;
+    if (!VmModifier.isConst(member.getModifiers())) {
+      throw exceptionBuilder().evalError("methodMustBeConst", methodName).build();
+    }
+  }
+
+  @Override
+  protected CallTarget getCallTarget(VmObjectLike owner) {
+    var method = owner.getMember(methodName);
+    assert method != null && method.isLocal();
+    return (CallTarget) method.getCallTarget().call(owner, owner);
+  }
+}

pkl-core/src/main/java/org/pkl/core/ast/expression/member/ReadAmbiguousLocalityPropertyNode.java

@@ -67,7 +67,7 @@ public final class ReadAmbiguousLocalityPropertyNode extends ExpressionNode {
       CompilerDirectives.transferToInterpreterAndInvalidate();
       readLocalPropertyNode =
           insert(
-              new ReadLocalPropertyNode(
+              new ReadLexicalLocalPropertyNode(
                   sourceSection, name.toLocalProperty(), levelsUp, needsConst));
     }
     return readLocalPropertyNode;

pkl-core/src/main/java/org/pkl/core/ast/expression/member/ReadLexicalLocalPropertyNode.java

@@ -0,0 +1,55 @@
+/*
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.pkl.core.ast.expression.member;
+
+import com.oracle.truffle.api.CompilerAsserts;
+import com.oracle.truffle.api.frame.VirtualFrame;
+import com.oracle.truffle.api.nodes.ExplodeLoop;
+import com.oracle.truffle.api.source.SourceSection;
+import org.pkl.core.runtime.Identifier;
+import org.pkl.core.runtime.VmObjectLike;
+import org.pkl.core.runtime.VmUtils;
+
+/** Reads a local non-constant property that is known to exist in the lexical scope of this node. */
+public final class ReadLexicalLocalPropertyNode extends AbstractReadLocalPropertyNode {
+  private final int levelsUp;
+
+  public ReadLexicalLocalPropertyNode(
+      SourceSection sourceSection, Identifier name, int levelsUp, boolean needsConst) {
+    super(sourceSection, name, needsConst);
+    CompilerAsserts.neverPartOfCompilation();
+    this.levelsUp = levelsUp;
+  }
+
+  @Override
+  @ExplodeLoop
+  public Object executeGeneric(VirtualFrame frame) {
+    var owner = VmUtils.getOwner(frame, levelsUp);
+    var property = getProperty(owner);
+    var constantValue = property.getConstantValue();
+    if (constantValue != null) {
+      return constantValue;
+    }
+
+    var receiver = (VmObjectLike) VmUtils.getReceiver(frame, levelsUp);
+    var result = receiver.getCachedValue(property);
+    if (result == null) {
+      result = getCallNode(property).call(receiver, owner, property.getName());
+      receiver.setCachedValue(property, result);
+    }
+    return result;
+  }
+}

pkl-core/src/main/java/org/pkl/core/ast/expression/member/ReadQualifiedLocalPropertyNode.java

@@ -0,0 +1,53 @@
+/*
+ * Copyright © 2026 Apple Inc. and the Pkl project authors. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.pkl.core.ast.expression.member;
+
+import com.oracle.truffle.api.frame.VirtualFrame;
+import com.oracle.truffle.api.source.SourceSection;
+import org.pkl.core.ast.ExpressionNode;
+import org.pkl.core.runtime.Identifier;
+import org.pkl.core.runtime.VmTyped;
+
+/** Reads a local property off of the receiver node. */
+public final class ReadQualifiedLocalPropertyNode extends AbstractReadLocalPropertyNode {
+  @Child private ExpressionNode getReceiverNode;
+
+  public ReadQualifiedLocalPropertyNode(
+      SourceSection sourceSection,
+      Identifier identifier,
+      boolean needsConst,
+      ExpressionNode getReceiverNode) {
+    super(sourceSection, identifier, needsConst);
+    this.getReceiverNode = getReceiverNode;
+  }
+
+  @Override
+  public Object executeGeneric(VirtualFrame frame) {
+    var receiver = (VmTyped) getReceiverNode.executeGeneric(frame);
+    var property = getProperty(receiver);
+    var constantValue = property.getConstantValue();
+    if (constantValue != null) {
+      return constantValue;
+    }
+
+    var result = receiver.getCachedValue(property);
+    if (result == null) {
+      result = getCallNode(property).call(receiver, receiver, property.getName());
+      receiver.setCachedValue(property, result);
+    }
+    return result;
+  }
+}

pkl-core/src/main/java/org/pkl/core/ast/expression/primary/GetTypeAliasModuleNode.java

@@ -0,0 +1,52 @@
+/*
+ * Copyright © 2026 Apple Inc. and the Pkl project authors. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.pkl.core.ast.expression.primary;
+
+import com.oracle.truffle.api.CompilerDirectives;
+import com.oracle.truffle.api.CompilerDirectives.CompilationFinal;
+import com.oracle.truffle.api.frame.VirtualFrame;
+import com.oracle.truffle.api.source.SourceSection;
+import org.jspecify.annotations.Nullable;
+import org.pkl.core.ast.ExpressionNode;
+import org.pkl.core.runtime.VmTyped;
+
+public final class GetTypeAliasModuleNode extends ExpressionNode {
+
+  @CompilationFinal private @Nullable VmTyped module;
+
+  public GetTypeAliasModuleNode(SourceSection sourceSection) {
+    super(sourceSection);
+  }
+
+  @Override
+  public boolean isInstrumentable() {
+    return false;
+  }
+
+  public void lateInitModule(VmTyped module) {
+    // must only set this once; the first typealias initialization wins.
+    // guards against nested typealiases; e.g. `typealias A = module; typealias B = A`
+    if (this.module != null) return;
+    CompilerDirectives.transferToInterpreterAndInvalidate();
+    this.module = module;
+  }
+
+  @Override
+  public Object executeGeneric(VirtualFrame frame) {
+    assert module != null;
+    return module;
+  }
+}

pkl-core/src/main/java/org/pkl/core/ast/member/TypeAliasNode.java

@@ -24,6 +24,7 @@ import java.util.List;
 import org.jspecify.annotations.Nullable;
 import org.pkl.core.TypeParameter;
 import org.pkl.core.ast.ExpressionNode;
+import org.pkl.core.ast.expression.primary.GetTypeAliasModuleNode;
 import org.pkl.core.ast.type.UnresolvedTypeNode;
 import org.pkl.core.runtime.VmTypeAlias;
 import org.pkl.core.runtime.VmTyped;
@@ -86,7 +87,15 @@ public final class TypeAliasNode extends ExpressionNode {
             frame.materialize());
 
     VmUtils.evaluateAnnotations(frame, annotationNodes, annotations);
-    cachedTypeAlias.initTypeCheckNode(typeAnnotationNode.execute(frame));
+    var bodyTypeNode = typeAnnotationNode.execute(frame);
+    bodyTypeNode.accept(
+        node -> {
+          if (node instanceof GetTypeAliasModuleNode getTypeAliasModuleNode) {
+            getTypeAliasModuleNode.lateInitModule(module);
+          }
+          return true;
+        });
+    cachedTypeAlias.initTypeCheckNode(bodyTypeNode);
 
     return cachedTypeAlias;
   }

pkl-core/src/main/java/org/pkl/core/ast/type/TypeNode.java

@@ -21,7 +21,6 @@ import com.oracle.truffle.api.CompilerDirectives.TruffleBoundary;
 import com.oracle.truffle.api.dsl.Cached;
 import com.oracle.truffle.api.dsl.Fallback;
 import com.oracle.truffle.api.dsl.Specialization;
-import com.oracle.truffle.api.frame.Frame;
 import com.oracle.truffle.api.frame.FrameDescriptor;
 import com.oracle.truffle.api.frame.FrameSlotKind;
 import com.oracle.truffle.api.frame.VirtualFrame;
@@ -2735,56 +2734,18 @@ public abstract class TypeNode extends PklNode {
       return getMirrors(typeArgumentNodes);
     }
 
-    /**
-     * A typealias body is effectively inlined into the type node, and not executed in its own
-     * frame.
-     *
-     * <p>Before executing the typealias body, use the owner and receiver of the original frame
-     * where the typealias was declared, so that we preserve its original scope.
-     */
     protected Object executeLazily(VirtualFrame frame, Object value) {
-      var prevOwner = VmUtils.getOwner(frame);
-      var prevReceiver = VmUtils.getReceiver(frame);
-      setOwner(frame, VmUtils.getOwner(typeAlias.getEnclosingFrame()));
-      setReceiver(frame, VmUtils.getReceiver(typeAlias.getEnclosingFrame()));
-
-      try {
-        return aliasedTypeNode.executeLazily(frame, value);
-      } finally {
-        setOwner(frame, prevOwner);
-        setReceiver(frame, prevReceiver);
-      }
+      return aliasedTypeNode.executeLazily(frame, value);
     }
 
     @Override
     public Object executeEagerly(VirtualFrame frame, Object value) {
-      var prevOwner = VmUtils.getOwner(frame);
-      var prevReceiver = VmUtils.getReceiver(frame);
-      setOwner(frame, VmUtils.getOwner(typeAlias.getEnclosingFrame()));
-      setReceiver(frame, VmUtils.getReceiver(typeAlias.getEnclosingFrame()));
-
-      try {
-        return aliasedTypeNode.executeEagerly(frame, value);
-      } finally {
-        setOwner(frame, prevOwner);
-        setReceiver(frame, prevReceiver);
-      }
+      return aliasedTypeNode.executeEagerly(frame, value);
     }
 
-    /** See docstring on {@link TypeAliasTypeNode#executeLazily}. */
     @Override
     public Object executeAndSet(VirtualFrame frame, Object value) {
-      var prevOwner = VmUtils.getOwner(frame);
-      var prevReceiver = VmUtils.getReceiver(frame);
-      setOwner(frame, VmUtils.getOwner(typeAlias.getEnclosingFrame()));
-      setReceiver(frame, VmUtils.getReceiver(typeAlias.getEnclosingFrame()));
-
-      try {
-        return aliasedTypeNode.executeAndSet(frame, value);
-      } finally {
-        setOwner(frame, prevOwner);
-        setReceiver(frame, prevReceiver);
-      }
+      return aliasedTypeNode.executeAndSet(frame, value);
     }
 
     @TruffleBoundary
@@ -2859,22 +2820,6 @@ public abstract class TypeNode extends PklNode {
     protected boolean isParametric() {
       return typeArgumentNodes.length > 0;
     }
-
-    // Note that mutating a frame's receiver and owner argument is very risky
-    // because any VmObject instantiated within the same root node execution
-    // holds a reference to (not immutable snapshot of) the frame
-    // via VmObjectLike.enclosingFrame.
-    // *Maybe* this works out for TypeAliasTypeNode because an object instantiated
-    // within a type constraint doesn't escape the constraint expression.
-    // If mutating receiver and owner can't be avoided, it would be safer
-    // to have VmObjectLike store them directly instead of storing enclosingFrame.
-    private static void setReceiver(Frame frame, Object receiver) {
-      frame.getArguments()[0] = receiver;
-    }
-
-    private static void setOwner(Frame frame, VmObjectLike owner) {
-      frame.getArguments()[1] = owner;
-    }
   }
 
   public static final class ConstrainedTypeNode extends TypeNode {

pkl-core/src/test/files/LanguageSnippetTests/input-helper/types/idType.pkl

@@ -0,0 +1 @@
+typealias Id<T> = T

pkl-core/src/test/files/LanguageSnippetTests/input-helper/types/typeAliasAmendBase.pkl

@@ -0,0 +1 @@
+name: String = "base"

pkl-core/src/test/files/LanguageSnippetTests/input-helper/types/typeAliasAmendModule.pkl

@@ -0,0 +1,9 @@
+amends "typeAliasAmendBase.pkl"
+
+local const function isValid(s: String): Boolean = s.startsWith("Bob")
+
+local typealias ValidString4 = String(isValid(this))
+
+local myProp: ValidString4 = "Bob Marley"
+
+name = myProp

pkl-core/src/test/files/LanguageSnippetTests/input-helper/types/typeAliasClosedModule.pkl

@@ -0,0 +1,3 @@
+const function isValid(s: String): Boolean = s.startsWith("Bob")
+
+typealias ValidString2 = String(isValid(this))

pkl-core/src/test/files/LanguageSnippetTests/input-helper/types/typeAliasLocalMethod.pkl

@@ -0,0 +1,3 @@
+local const function isValid(s: String): Boolean = s.startsWith("Bob")
+
+typealias ValidString3 = String(isValid(this))

pkl-core/src/test/files/LanguageSnippetTests/input-helper/types/typeAliasModule.pkl

@@ -0,0 +1 @@
+typealias MyModule = module

pkl-core/src/test/files/LanguageSnippetTests/input-helper/types/typeAliasOpenModule.pkl

@@ -0,0 +1,5 @@
+open module typeAliasOpenModule
+
+const function isValid(s: String): Boolean = s.startsWith("Bob")
+
+typealias ValidString = String(isValid(this))

pkl-core/src/test/files/LanguageSnippetTests/input-helper/types/typealias1.pkl

@@ -0,0 +1,3 @@
+const name = "Bob"
+
+typealias Inner = String(startsWith(name))

pkl-core/src/test/files/LanguageSnippetTests/input-helper/types/typealias2.pkl

@@ -0,0 +1,5 @@
+import "typealias1.pkl"
+
+const name = "Alice"
+
+typealias Outer = typealias1.Inner

pkl-core/src/test/files/LanguageSnippetTests/input/types/typeAlias5.pkl

@@ -0,0 +1,8 @@
+import "../../input-helper/types/idType.pkl"
+
+hidden modules: Listing<idType.Id<module>> = new {
+  new module {}
+  new module {}
+}
+
+res = modules.length

pkl-core/src/test/files/LanguageSnippetTests/input/types/typeAlias6.pkl

@@ -0,0 +1,3 @@
+import "../../input-helper/types/typeAliasModule.pkl"
+
+res: typeAliasModule = module

pkl-core/src/test/files/LanguageSnippetTests/input/types/typeAliasConstraint4.pkl

@@ -0,0 +1,3 @@
+import "../../input-helper/types/typealias2.pkl"
+
+myProp: typealias2.Outer = "Alice Jenkins"

pkl-core/src/test/files/LanguageSnippetTests/input/types/typeAliasConstraint5.pkl

@@ -0,0 +1,5 @@
+import "../../input-helper/types/typeAliasOpenModule.pkl"
+
+const function isValid(s: String): Boolean = s.startsWith("Alice")
+
+myProp: typeAliasOpenModule.ValidString = "Alice Jenkins"

pkl-core/src/test/files/LanguageSnippetTests/input/types/typeAliasConstraint6.pkl

@@ -0,0 +1,5 @@
+import "../../input-helper/types/typeAliasClosedModule.pkl"
+
+const function isValid(s: String): Boolean = s.startsWith("Alice")
+
+myProp: typeAliasClosedModule.ValidString2 = "Alice Jenkins"

pkl-core/src/test/files/LanguageSnippetTests/input/types/typeAliasConstraint7.pkl

@@ -0,0 +1,5 @@
+import "../../input-helper/types/typeAliasLocalMethod.pkl"
+
+local const function isValid(s: String): Boolean = s.startsWith("Alice")
+
+myProp: typeAliasLocalMethod.ValidString3 = "Alice Jenkins"

pkl-core/src/test/files/LanguageSnippetTests/input/types/typeAliasConstraint8.pkl

@@ -0,0 +1,5 @@
+import "../../input-helper/types/typeAliasAmendModule.pkl"
+
+local const function isValid(s: String): Boolean = s.startsWith("Alice")
+
+res = typeAliasAmendModule.name

pkl-core/src/test/files/LanguageSnippetTests/output/types/typeAlias5.pcf

@@ -0,0 +1 @@
+res = 2

pkl-core/src/test/files/LanguageSnippetTests/output/types/typeAlias6.err

@@ -0,0 +1,15 @@
+–– Pkl Error ––
+Expected value of type `typeAliasModule`, but got type `typeAlias6`.
+Value: new ModuleClass { res = ? }
+
+x | res: typeAliasModule = module
+         ^^^^^^^^^^^^^^^
+at typeAlias6#res (file:///$snippetsDir/input/types/typeAlias6.pkl)
+
+xxx | renderer.renderDocument(value)
+      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+at pkl.base#Module.output.text (pkl:base)
+
+xxx | if (renderer is BytesRenderer) renderer.renderDocument(value) else text.encodeToBytes("UTF-8")
+                                                                         ^^^^
+at pkl.base#Module.output.bytes (pkl:base)

pkl-core/src/test/files/LanguageSnippetTests/output/types/typeAliasConstraint4.err

@@ -0,0 +1,23 @@
+–– Pkl Error ––
+Type constraint `startsWith(name)` violated.
+Value: "Alice Jenkins"
+
+    startsWith(name)
+    │          │
+    false      "Bob"
+
+x | typealias Inner = String(startsWith(name))
+                             ^^^^^^^^^^^^^^^^
+at typeAliasConstraint4#myProp (file:///$snippetsDir/input-helper/types/typealias1.pkl)
+
+x | myProp: typealias2.Outer = "Alice Jenkins"
+                               ^^^^^^^^^^^^^^^
+at typeAliasConstraint4#myProp (file:///$snippetsDir/input/types/typeAliasConstraint4.pkl)
+
+xxx | renderer.renderDocument(value)
+      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+at pkl.base#Module.output.text (pkl:base)
+
+xxx | if (renderer is BytesRenderer) renderer.renderDocument(value) else text.encodeToBytes("UTF-8")
+                                                                         ^^^^
+at pkl.base#Module.output.bytes (pkl:base)

pkl-core/src/test/files/LanguageSnippetTests/output/types/typeAliasConstraint5.err

@@ -0,0 +1,23 @@
+–– Pkl Error ––
+Type constraint `isValid(this)` violated.
+Value: "Alice Jenkins"
+
+    isValid(this)
+    │       │
+    false   "Alice Jenkins"
+
+x | typealias ValidString = String(isValid(this))
+                                   ^^^^^^^^^^^^^
+at typeAliasConstraint5#myProp (file:///$snippetsDir/input-helper/types/typeAliasOpenModule.pkl)
+
+x | myProp: typeAliasOpenModule.ValidString = "Alice Jenkins"
+                                              ^^^^^^^^^^^^^^^
+at typeAliasConstraint5#myProp (file:///$snippetsDir/input/types/typeAliasConstraint5.pkl)
+
+xxx | renderer.renderDocument(value)
+      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+at pkl.base#Module.output.text (pkl:base)
+
+xxx | if (renderer is BytesRenderer) renderer.renderDocument(value) else text.encodeToBytes("UTF-8")
+                                                                         ^^^^
+at pkl.base#Module.output.bytes (pkl:base)

pkl-core/src/test/files/LanguageSnippetTests/output/types/typeAliasConstraint6.err

@@ -0,0 +1,23 @@
+–– Pkl Error ––
+Type constraint `isValid(this)` violated.
+Value: "Alice Jenkins"
+
+    isValid(this)
+    │       │
+    false   "Alice Jenkins"
+
+x | typealias ValidString2 = String(isValid(this))
+                                    ^^^^^^^^^^^^^
+at typeAliasConstraint6#myProp (file:///$snippetsDir/input-helper/types/typeAliasClosedModule.pkl)
+
+x | myProp: typeAliasClosedModule.ValidString2 = "Alice Jenkins"
+                                                 ^^^^^^^^^^^^^^^
+at typeAliasConstraint6#myProp (file:///$snippetsDir/input/types/typeAliasConstraint6.pkl)
+
+xxx | renderer.renderDocument(value)
+      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+at pkl.base#Module.output.text (pkl:base)
+
+xxx | if (renderer is BytesRenderer) renderer.renderDocument(value) else text.encodeToBytes("UTF-8")
+                                                                         ^^^^
+at pkl.base#Module.output.bytes (pkl:base)

pkl-core/src/test/files/LanguageSnippetTests/output/types/typeAliasConstraint7.err

@@ -0,0 +1,23 @@
+–– Pkl Error ––
+Type constraint `isValid(this)` violated.
+Value: "Alice Jenkins"
+
+    isValid(this)
+    │       │
+    false   "Alice Jenkins"
+
+x | typealias ValidString3 = String(isValid(this))
+                                    ^^^^^^^^^^^^^
+at typeAliasConstraint7#myProp (file:///$snippetsDir/input-helper/types/typeAliasLocalMethod.pkl)
+
+x | myProp: typeAliasLocalMethod.ValidString3 = "Alice Jenkins"
+                                                ^^^^^^^^^^^^^^^
+at typeAliasConstraint7#myProp (file:///$snippetsDir/input/types/typeAliasConstraint7.pkl)
+
+xxx | renderer.renderDocument(value)
+      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+at pkl.base#Module.output.text (pkl:base)
+
+xxx | if (renderer is BytesRenderer) renderer.renderDocument(value) else text.encodeToBytes("UTF-8")
+                                                                         ^^^^
+at pkl.base#Module.output.bytes (pkl:base)

pkl-core/src/test/files/LanguageSnippetTests/output/types/typeAliasConstraint8.pcf

@@ -0,0 +1 @@
+res = "Bob Marley"