Remove abstract properties (#1781)

pkl-core/src/main/java/org/pkl/core/ast/VmModifier.java

@@ -71,6 +71,7 @@ public final class VmModifier {
 
   public static final int VALID_METHOD_MODIFIERS = ABSTRACT | LOCAL | EXTERNAL | CONST;
 
+  // for compat, properties may be parsed with abstract modifier but this is ignored
   public static final int VALID_PROPERTY_MODIFIERS =
       ABSTRACT | LOCAL | HIDDEN | EXTERNAL | FIXED | CONST;
 

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

@@ -1476,7 +1476,7 @@ public class AstBuilder extends AbstractAstBuilder<Object> {
     var scope = (ModuleScope) symbolTable.getCurrentScope();
     scope.setModifiers(modifiers);
 
-    checkAbstractMembersAllowed(modifiers, mod.getProperties(), mod.getMethods());
+    checkAbstractMethodsAllowed(modifiers, mod.getMethods(), "module");
 
     // visit imports first so that we already have the object member name available
     var imports = mod.getImports();
@@ -1722,7 +1722,7 @@ public class AstBuilder extends AbstractAstBuilder<Object> {
           List<ClassProperty> properties = bodyNode != null ? bodyNode.getProperties() : List.of();
           List<ClassMethod> methods = bodyNode != null ? bodyNode.getMethods() : List.of();
           registerClassScopeNames(scope, properties, methods);
-          checkAbstractMembersAllowed(modifiers, properties, methods);
+          checkAbstractMethodsAllowed(modifiers, methods, "class");
 
           var supertypeCtx = clazz.getSuperClass();
 
@@ -1813,26 +1813,19 @@ public class AstBuilder extends AbstractAstBuilder<Object> {
     };
   }
 
-  private void checkAbstractMembersAllowed(
+  private void checkAbstractMethodsAllowed(
-      int enclosingModifiers, List<ClassProperty> properties, List<ClassMethod> methods) {
+      int enclosingModifiers, List<ClassMethod> methods, String context) {
     if (VmModifier.isAbstract(enclosingModifiers)) {
       return;
     }
-    for (var property : properties) {
-      checkMemberNotAbstract(property.getModifiers());
-    }
     for (var method : methods) {
-      checkMemberNotAbstract(method.getModifiers());
+      for (var modifier : method.getModifiers()) {
-    }
+        if (modifier.getValue() == ModifierValue.ABSTRACT) {
-  }
+          throw exceptionBuilder()
-
+              .evalError("abstractMethodInNonAbstractType", context)
-  private void checkMemberNotAbstract(List<Modifier> modifiers) {
+              .withSourceSection(createSourceSection(modifier.span()))
-    for (var modifier : modifiers) {
+              .build();
-      if (modifier.getValue() == ModifierValue.ABSTRACT) {
+        }
-        throw exceptionBuilder()
-            .evalError("abstractMemberInNonAbstractClass")
-            .withSourceSection(createSourceSection(modifier.span()))
-            .build();
       }
     }
   }
@@ -1878,9 +1871,11 @@ public class AstBuilder extends AbstractAstBuilder<Object> {
     var headerEnd = typeAnnotation != null ? typeAnnotation.span() : name.span();
     var headerSection = createSourceSection(headerStart.endWith(headerEnd));
 
-    var modifiers =
+    var fullModifiers =
         doVisitModifiers(
             modifierList, VmModifier.VALID_PROPERTY_MODIFIERS, "invalidPropertyModifier");
+    // for compat, properties may be abstract, but ignore this
+    var modifiers = fullModifiers & ~VmModifier.ABSTRACT;
 
     var isLocal = VmModifier.isLocal(modifiers);
     var propertyName = org.pkl.core.runtime.Identifier.property(name.getValue(), isLocal);
@@ -1899,12 +1894,6 @@ public class AstBuilder extends AbstractAstBuilder<Object> {
                   .withSourceSection(headerSection)
                   .build();
             }
-            if (VmModifier.isAbstract(modifiers)) {
-              throw exceptionBuilder()
-                  .evalError("abstractMemberCannotHaveBody")
-                  .withSourceSection(headerSection)
-                  .build();
-            }
             bodyNode = visitExpr(expr);
           } else if (!objectBodies.isEmpty()) { // prop { ... }
             if (typeAnnotation != null) {
@@ -1931,9 +1920,6 @@ public class AstBuilder extends AbstractAstBuilder<Object> {
               if (bodyNode instanceof LanguageAwareNode languageAwareNode) {
                 languageAwareNode.initLanguage(language);
               }
-            } else if (VmModifier.isAbstract(modifiers)) {
-              bodyNode =
-                  new CannotInvokeAbstractPropertyNode(headerSection, scope.getQualifiedName());
             } else {
               bodyNode = null; // will be given a default by UnresolvedPropertyNode
             }

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

@@ -1,36 +0,0 @@
-/*
- * Copyright © 2024 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.builder;
-
-import com.oracle.truffle.api.CompilerDirectives;
-import com.oracle.truffle.api.frame.VirtualFrame;
-import com.oracle.truffle.api.source.SourceSection;
-import org.pkl.core.ast.ExpressionNode;
-
-public final class CannotInvokeAbstractPropertyNode extends ExpressionNode {
-  private final String propertyName;
-
-  public CannotInvokeAbstractPropertyNode(SourceSection section, String propertyName) {
-    super(section);
-    this.propertyName = propertyName;
-  }
-
-  @Override
-  public Object executeGeneric(VirtualFrame frame) {
-    CompilerDirectives.transferToInterpreter();
-    throw exceptionBuilder().evalError("cannotInvokeAbstractProperty", propertyName).build();
-  }
-}

pkl-core/src/main/java/org/pkl/core/runtime/MirrorFactories.java

@@ -180,8 +180,7 @@ public final class MirrorFactories {
         .addProperty(
             "defaultValue",
             property ->
-                property.isAbstract()
+                property.isExternal()
-                        || property.isExternal()
                         || property
                             .getInitializer()
                             .isUndefined(VmUtils.createEmptyMaterializedFrame())

pkl-core/src/main/resources/org/pkl/core/errorMessages.properties

@@ -43,9 +43,6 @@ Type alias definitions must not be cyclic.
 cannotInvokeAbstractMethod=\
 Cannot invoke abstract method `{0}`.
 
-cannotInvokeAbstractProperty=\
-Cannot invoke abstract property `{0}`.
-
 cannotInvokeSupermethodFromHere=\
 Cannot invoke a supermethod from here.
 
@@ -289,8 +286,8 @@ External members cannot have a body.
 abstractMemberCannotHaveBody=\
 Abstract members cannot have a body.
 
-abstractMemberInNonAbstractClass=\
+abstractMethodInNonAbstractType=\
-Cannot define an abstract member in a non-abstract class.\n\
+Cannot define an abstract method in a non-abstract {0}.\n\
 \n\
 A member can only be `abstract` if its enclosing class is also `abstract`.
 

pkl-core/src/test/files/LanguageSnippetTests/input/errors/abstractMemberInNonAbstractClass.pkl

@@ -1,5 +0,0 @@
-class Foo {
-  abstract bar: Int
-}
-
-res = new Foo { bar = 5 }

pkl-core/src/test/files/LanguageSnippetTests/input/errors/abstractMemberInNonAbstractModule.pkl

@@ -1 +0,0 @@
-abstract foo: Int

pkl-core/src/test/files/LanguageSnippetTests/input/errors/abstractMethodInNonAbstractModule.pkl

@@ -0,0 +1 @@
+abstract function foo(): Int

pkl-core/src/test/files/LanguageSnippetTests/input/internal/polymorphicCallSite.pkl

@@ -18,7 +18,7 @@ res3 = f(List(1, 2))
 res4 = f(Set(1, 2))
 
 abstract class Animal {
-  abstract size: String
+  size: String
   abstract function walk(): String
 }
 

pkl-core/src/test/files/LanguageSnippetTests/output/errors/abstractMemberInNonAbstractClass.err

@@ -1,8 +0,0 @@
-–– Pkl Error ––
-Cannot define an abstract member in a non-abstract class.
-
-x | abstract bar: Int
-    ^^^^^^^^
-at abstractMemberInNonAbstractClass#Foo (file:///$snippetsDir/input/errors/abstractMemberInNonAbstractClass.pkl)
-
-A member can only be `abstract` if its enclosing class is also `abstract`.

pkl-core/src/test/files/LanguageSnippetTests/output/errors/abstractMemberInNonAbstractModule.err

@@ -1,8 +0,0 @@
-–– Pkl Error ––
-Cannot define an abstract member in a non-abstract class.
-
-x | abstract foo: Int
-    ^^^^^^^^
-at abstractMemberInNonAbstractModule (file:///$snippetsDir/input/errors/abstractMemberInNonAbstractModule.pkl)
-
-A member can only be `abstract` if its enclosing class is also `abstract`.

pkl-core/src/test/files/LanguageSnippetTests/output/errors/abstractMethodInNonAbstractClass.err

@@ -1,5 +1,5 @@
 –– Pkl Error ––
-Cannot define an abstract member in a non-abstract class.
+Cannot define an abstract method in a non-abstract class.
 
 x | abstract function bar(): Int
     ^^^^^^^^

pkl-core/src/test/files/LanguageSnippetTests/output/errors/abstractMethodInNonAbstractModule.err

@@ -0,0 +1,8 @@
+–– Pkl Error ––
+Cannot define an abstract method in a non-abstract module.
+
+x | abstract function foo(): Int
+    ^^^^^^^^
+at abstractMethodInNonAbstractModule (file:///$snippetsDir/input/errors/abstractMethodInNonAbstractModule.pkl)
+
+A member can only be `abstract` if its enclosing class is also `abstract`.

pkl-doc/src/test/files/DocGeneratorTest/input/com.package1/classInheritance.pkl

@@ -3,7 +3,7 @@ module com.package1.classInheritance
 
 abstract class MyClass1 {
   /// Inherited property comment.
-  abstract property1: Boolean
+  property1: Boolean
 
   /// function method1 in class MyClass1.
   abstract function method1(arg: String): Boolean

pkl-doc/src/test/files/DocGeneratorTest/input/com.package1/classPropertyModifiers.pkl

@@ -8,9 +8,6 @@ abstract class Modifiers {
   /// Property with `hidden` modifier.
   hidden property2: Float = 3.14159265359
 
-  /// Property with `abstract` modifier.
-  abstract property3: Float
-
   /// Property with multiple modifiers.
   abstract hidden property4: Float
 

pkl-doc/src/test/files/DocGeneratorTest/input/com.package1/modulePropertyModifiers.pkl

@@ -10,10 +10,4 @@ hidden property2: Float = 3.14159265359
 /*
 /// Property with `external` modifier.
 external property3: Float
-
-/// Property with `abstract` modifier.
-abstract property4: Float
-
-/// Property with multiple modifiers.
-abstract external hidden property5: Float
 */

pkl-doc/src/test/files/DocGeneratorTest/output/run-1/com.package1/1.2.3/classInheritance/MyClass1.html

@@ -50,7 +50,7 @@
             <div id="property1" class="anchor"> </div>
             <div class="member"><a class="member-selflink material-icons" href="#property1">link</a>
               <div class="member-left">
-                <div class="member-modifiers">abstract </div>
+                <div class="member-modifiers"></div>
               </div>
               <div class="member-main">
                 <div class="member-signature"><span class="name-decl">property1</span>: <a href="https://pages.github.com/apple/pkl/stdlib/pkl/0.24.0/base/Boolean.html" class="name-ref">Boolean</a><a class="member-source-link" href="https://example.com/package1/classInheritance.pkl#L123-L456">Source</a></div>

pkl-doc/src/test/files/DocGeneratorTest/output/run-1/com.package1/1.2.3/classPropertyModifiers/Modifiers.html

@@ -58,23 +58,11 @@
               </div>
             </div>
           </li>
-          <li>
-            <div id="property3" class="anchor"> </div>
-            <div class="member"><a class="member-selflink material-icons" href="#property3">link</a>
-              <div class="member-left">
-                <div class="member-modifiers">abstract </div>
-              </div>
-              <div class="member-main">
-                <div class="member-signature"><span class="name-decl">property3</span>: <a href="https://pages.github.com/apple/pkl/stdlib/pkl/0.24.0/base/Float.html" class="name-ref">Float</a><a class="member-source-link" href="https://example.com/package1/classPropertyModifiers.pkl#L123-L456">Source</a></div>
-                <div class="doc-comment"><p>Property with <code>abstract</code> modifier.</p></div>
-              </div>
-            </div>
-          </li>
           <li>
             <div id="property4" class="anchor"> </div>
             <div class="member hidden-member"><a class="member-selflink material-icons" href="#property4">link</a>
               <div class="member-left">
-                <div class="member-modifiers">abstract hidden </div>
+                <div class="member-modifiers">hidden </div>
               </div>
               <div class="member-main">
                 <div class="member-signature"><span class="name-decl">property4</span>: <a href="https://pages.github.com/apple/pkl/stdlib/pkl/0.24.0/base/Float.html" class="name-ref">Float</a><a class="member-source-link" href="https://example.com/package1/classPropertyModifiers.pkl#L123-L456">Source</a></div>

pkl-doc/src/test/files/DocGeneratorTest/output/run-2/com.package1/1.2.3/classInheritance/MyClass1.html

@@ -50,7 +50,7 @@
             <div id="property1" class="anchor"> </div>
             <div class="member"><a class="member-selflink material-icons" href="#property1">link</a>
               <div class="member-left">
-                <div class="member-modifiers">abstract </div>
+                <div class="member-modifiers"></div>
               </div>
               <div class="member-main">
                 <div class="member-signature"><span class="name-decl">property1</span>: <a href="https://pages.github.com/apple/pkl/stdlib/pkl/0.24.0/base/Boolean.html" class="name-ref">Boolean</a><a class="member-source-link" href="https://example.com/package1/classInheritance.pkl#L123-L456">Source</a></div>

pkl-doc/src/test/files/DocGeneratorTest/output/run-2/com.package1/1.2.3/classPropertyModifiers/Modifiers.html

@@ -58,23 +58,11 @@
               </div>
             </div>
           </li>
-          <li>
-            <div id="property3" class="anchor"> </div>
-            <div class="member"><a class="member-selflink material-icons" href="#property3">link</a>
-              <div class="member-left">
-                <div class="member-modifiers">abstract </div>
-              </div>
-              <div class="member-main">
-                <div class="member-signature"><span class="name-decl">property3</span>: <a href="https://pages.github.com/apple/pkl/stdlib/pkl/0.24.0/base/Float.html" class="name-ref">Float</a><a class="member-source-link" href="https://example.com/package1/classPropertyModifiers.pkl#L123-L456">Source</a></div>
-                <div class="doc-comment"><p>Property with <code>abstract</code> modifier.</p></div>
-              </div>
-            </div>
-          </li>
           <li>
             <div id="property4" class="anchor"> </div>
             <div class="member hidden-member"><a class="member-selflink material-icons" href="#property4">link</a>
               <div class="member-left">
-                <div class="member-modifiers">abstract hidden </div>
+                <div class="member-modifiers">hidden </div>
               </div>
               <div class="member-main">
                 <div class="member-signature"><span class="name-decl">property4</span>: <a href="https://pages.github.com/apple/pkl/stdlib/pkl/0.24.0/base/Float.html" class="name-ref">Float</a><a class="member-source-link" href="https://example.com/package1/classPropertyModifiers.pkl#L123-L456">Source</a></div>

stdlib/base.pkl

@@ -740,28 +740,28 @@ class Resource {
 /// use [Number] instead of [Float] in type annotations.
 abstract external class Number extends Any {
   /// A [Duration] with value [this] and unit `"ns"` (nanoseconds).
-  abstract ns: Duration
+  ns: Duration
 
   /// A [Duration] with value [this] and unit `"us"` (microseconds).
-  abstract us: Duration
+  us: Duration
 
   /// A [Duration] with value [this] and unit `"ms"` (milliseconds).
-  abstract ms: Duration
+  ms: Duration
 
   /// A [Duration] with value [this] and unit `"s"` (seconds).
-  abstract s: Duration
+  s: Duration
 
   /// A [Duration] with value [this] and unit `"min"` (minutes).
-  abstract min: Duration
+  min: Duration
 
   /// A [Duration] with value [this] and unit `"h"` (hours).
-  abstract h: Duration
+  h: Duration
 
   /// A [Duration] with value [this] and unit `"d"` (days).
-  abstract d: Duration
+  d: Duration
 
   /// A [DataSize] with value [this] and unit `"b"` (bytes).
-  abstract b: DataSize
+  b: DataSize
 
   /// A [DataSize] with value [this] and unit `"kb"` (kilobytes).
   ///
@@ -769,7 +769,7 @@ abstract external class Number extends Any {
   /// ```
   /// 1.kb == 1000.b
   /// ```
-  abstract kb: DataSize
+  kb: DataSize
 
   /// A [DataSize] with value [this] and unit `"mb"` (megabytes).
   ///
@@ -777,7 +777,7 @@ abstract external class Number extends Any {
   /// ```
   /// 1.mb == 1000.kb
   /// ```
-  abstract mb: DataSize
+  mb: DataSize
 
   /// A [DataSize] with value [this] and unit `"gb"` (gigabytes).
   ///
@@ -785,7 +785,7 @@ abstract external class Number extends Any {
   /// ```
   /// 1.gb == 1000.mb
   /// ```
-  abstract gb: DataSize
+  gb: DataSize
 
   /// A [DataSize] with value [this] and unit `"tb"` (terabytes).
   ///
@@ -793,7 +793,7 @@ abstract external class Number extends Any {
   /// ```
   /// 1.tb == 1000.gb
   /// ```
-  abstract tb: DataSize
+  tb: DataSize
 
   /// A [DataSize] with value [this] and unit `"pb"` (petabytes).
   ///
@@ -801,7 +801,7 @@ abstract external class Number extends Any {
   /// ```
   /// 1.pb == 1000.tb
   /// ```
-  abstract pb: DataSize
+  pb: DataSize
 
   /// A [DataSize] with value [this] and unit `"kib"` (kibibytes).
   ///
@@ -809,7 +809,7 @@ abstract external class Number extends Any {
   /// ```
   /// 1.kib == 1024.b
   /// ```
-  abstract kib: DataSize
+  kib: DataSize
 
   /// A [DataSize] with value [this] and unit `"mib"` (mebibytes).
   ///
@@ -817,7 +817,7 @@ abstract external class Number extends Any {
   /// ```
   /// 1.mib == 1024.kib
   /// ```
-  abstract mib: DataSize
+  mib: DataSize
 
   /// A [DataSize] with value [this] and unit `"gib"` (gibibytes).
   ///
@@ -825,7 +825,7 @@ abstract external class Number extends Any {
   /// ```
   /// 1.gib == 1024.mib
   /// ```
-  abstract gib: DataSize
+  gib: DataSize
 
   /// A [DataSize] with value [this] and unit `"tib"` (tebibytes).
   ///
@@ -833,7 +833,7 @@ abstract external class Number extends Any {
   /// ```
   /// 1.tib == 1024.gib
   /// ```
-  abstract tib: DataSize
+  tib: DataSize
 
   /// A [DataSize] with value [this] and unit `"pib"` (pebibytes).
   ///
@@ -841,14 +841,14 @@ abstract external class Number extends Any {
   /// ```
   /// 1.pib == 1024.tib
   /// ```
-  abstract pib: DataSize
+  pib: DataSize
 
   /// The sign of this number.
   ///
   /// Returns `0` for `0`, `0.0`, `-0.0`, and [NaN],
   /// `1` for positive numbers (including [Infinity]),
   /// and `-1` for negative numbers (including `-`[Infinity]).
-  abstract sign: Number
+  sign: Number
 
   /// The absolute value of this number.
   ///
@@ -862,7 +862,7 @@ abstract external class Number extends Any {
   /// (-Infinity).abs == Infinity
   /// NaN.abs == NaN
   /// ```
-  abstract abs: Number
+  abs: Number
 
   /// Rounds this number to the next mathematical integer towards [Infinity].
   ///
@@ -870,7 +870,7 @@ abstract external class Number extends Any {
   /// If [this] is [NaN], [Infinity], -[Infinity], `0.0`, or `-0.0`, returns [this].
   /// Otherwise, returns the smallest [Float] that is greater than or equal to [this]
   /// and is equal to a mathematical integer.
-  abstract ceil: Number
+  ceil: Number
 
   /// Rounds this number to the next mathematical integer towards -[Infinity].
   ///
@@ -878,7 +878,7 @@ abstract external class Number extends Any {
   /// If [this] is [NaN], [Infinity], -[Infinity], `0.0`, or `-0.0`, returns [this].
   /// Otherwise, returns the largest [Float] that is less than or equal to [this]
   /// and is equal to a mathematical integer.
-  abstract floor: Number
+  floor: Number
 
   /// Rounds this number to the nearest mathematical integer, breaking ties in favor
   /// of the even integer.
@@ -946,23 +946,23 @@ abstract external class Number extends Any {
   /// !(-Infinity).isPositive
   /// !NaN.isPositive
   /// ```
-  abstract isPositive: Boolean
+  isPositive: Boolean
 
   /// Tells if this number is neither [NaN] nor [isInfinite].
-  abstract isFinite: Boolean
+  isFinite: Boolean
 
   /// Tells if this number is [Infinity] or -[Infinity].
-  abstract isInfinite: Boolean
+  isInfinite: Boolean
 
   /// Tells if this number is [NaN].
   ///
   /// Always use this method when testing for [NaN].
   /// Note that `x == NaN` is *not* a correct way to test for [NaN] because `NaN != NaN` as per the
   /// IEEE spec.
-  abstract isNaN: Boolean
+  isNaN: Boolean
 
   /// Tells if this number is not 0.
-  abstract isNonZero: Boolean
+  isNonZero: Boolean
 
   /// Tells if this number is greater than or equal to [start] and less than or equal to
   /// [inclusiveEnd].
@@ -2419,7 +2419,7 @@ abstract external class Collection<out Element> extends Any {
   /// List().length == 0
   /// ```
   @AlsoKnownAs { names { "size"; "count" } }
-  abstract length: Int
+  length: Int
 
   /// Tells whether this collection is empty.
   ///
@@ -2428,7 +2428,7 @@ abstract external class Collection<out Element> extends Any {
   /// !List(1, 2, 3).isEmpty
   /// List().isEmpty
   /// ```
-  abstract isEmpty: Boolean
+  isEmpty: Boolean
 
   /// Tells whether this collection is not empty.
   ///
@@ -2438,7 +2438,7 @@ abstract external class Collection<out Element> extends Any {
   /// !List().isNotEmpty
   /// ```
   @Since { version = "0.31.0" }
-  abstract isNotEmpty: Boolean
+  isNotEmpty: Boolean
 
   /// The first element in this collection.
   ///
@@ -2450,11 +2450,11 @@ abstract external class Collection<out Element> extends Any {
   /// import("pkl:test").catch(() -> List().first)
   /// ```
   @AlsoKnownAs { names { "head" } }
-  abstract first: Element
+  first: Element
 
   /// Same as [first] but returns [null] if this collection is empty.
   @AlsoKnownAs { names { "head" } }
-  abstract firstOrNull: Element?
+  firstOrNull: Element?
 
   /// The tail of this collection.
   ///
@@ -2466,11 +2466,11 @@ abstract external class Collection<out Element> extends Any {
   /// import("pkl:test").catch(() -> List().rest)
   /// ```
   @AlsoKnownAs { names { "tail" } }
-  abstract rest: Collection<Element>
+  rest: Collection<Element>
 
   /// Same as [rest] but returns [null] if this collection is empty.
   @AlsoKnownAs { names { "tail" } }
-  abstract restOrNull: Collection<Element>?
+  restOrNull: Collection<Element>?
 
   /// The last element in this collection.
   ///
@@ -2481,10 +2481,10 @@ abstract external class Collection<out Element> extends Any {
   /// List(1, 2, 3).last == 3
   /// import("pkl:test").catch(() -> List().last)
   /// ```
-  abstract last: Element
+  last: Element
 
   /// Same as [last] but returns [null] if this collection is empty.
-  abstract lastOrNull: Element?
+  lastOrNull: Element?
 
   /// The single element in this collection.
   ///
@@ -2496,10 +2496,10 @@ abstract external class Collection<out Element> extends Any {
   /// throws(() -> List().single)
   /// throws(() -> List(1, 2, 3).single)
   /// ```
-  abstract single: Element
+  single: Element
 
   /// Same as [single] but returns [null] if this collection is empty or has more than one element.
-  abstract singleOrNull: Element?
+  singleOrNull: Element?
 
   /// Tests if [element] is contained in this collection.
   ///
@@ -2790,10 +2790,10 @@ abstract external class Collection<out Element> extends Any {
   /// Shorthand for `minWith((a, b) -> a < b)`.
   ///
   /// Throws if this collection is empty, or if any two elements cannot be compared with `<`.
-  abstract min: Element
+  min: Element
 
   /// Same as [min] but returns [null] if this collection is empty.
-  abstract minOrNull: Element?
+  minOrNull: Element?
 
   /// Returns the first element in this collection that is less than or equal to any other element
   /// after applying [selector].
@@ -2824,10 +2824,10 @@ abstract external class Collection<out Element> extends Any {
   /// Shorthand for `maxWith((a, b) -> a < b)`.
   ///
   /// Throws if this collection is empty, or if any two elements cannot be compared with `<`.
-  abstract max: Element
+  max: Element
 
   /// Same as [max] but returns [null] if this collection empty.
-  abstract maxOrNull: Element
+  maxOrNull: Element
 
   /// Returns the first element in this collection that is greater than or equal to any other
   /// element after applying [selector].

stdlib/reflect.pkl

@@ -216,7 +216,7 @@ external class Module extends Declaration {
 /// A class or type alias declaration.
 abstract external class TypeDeclaration extends Declaration {
   /// The class or type alias reflected upon.
-  abstract hidden reflectee: base.Class | base.TypeAlias
+  hidden reflectee: base.Class | base.TypeAlias
 
   /// The module enclosing this type declaration.
   ///
@@ -224,7 +224,7 @@ abstract external class TypeDeclaration extends Declaration {
   hidden enclosingDeclaration: Module
 
   /// The type parameters of this type declaration.
-  abstract typeParameters: List<TypeParameter>
+  typeParameters: List<TypeParameter>
 }
 
 /// A class declaration.