fix: remove default constructors and require explicit construct new() for all user classes

The compiler no longer auto-generates a default `new()` constructor for classes. All classes must now explicitly define `construct new() {}` to be instantiable. This change removes the `createDefaultConstructor` function from the compiler, eliminates the `return_this` primitive used by Object's default initializer, and adds explicit constructors to all test and example classes. Core metaclasses (Bool, Class, Null, Num, Object, Range, Sequence) now correctly reject `new()` calls with runtime errors.

test/language/class/lowercase_name_inside_body.wren

@@ -1,4 +1,6 @@
 class foo {
+  construct new() {}
+
   static callFoo {
     IO.print(foo)
   }

test/language/class/name_inside_body.wren

@@ -1,4 +1,6 @@
 class Foo {
+  construct new() {}
+
   static sayName {
     IO.print(Foo)
   }

test/language/closure/close_over_method_parameter.wren

@@ -1,6 +1,8 @@
 var F = null
 
 class Foo {
+  construct new() {}
+
   method(param) {
     F = Fn.new {
       IO.print(param)

test/language/closure/closed_closure_in_method.wren

@@ -4,6 +4,8 @@ var foo = null
 {
   var local = "local"
   class Foo {
+    construct new() {}
+
     method {
       IO.print(local)
     }

test/language/closure/open_closure_in_method.wren

@@ -2,6 +2,8 @@
 {
   var local = "local"
   class Foo {
+    construct new() {}
+
     method {
       IO.print(local)
     }

test/language/conditional/precedence.wren

@@ -1,4 +1,5 @@
 class Foo {
+  construct new() {}
   static bar { true }
   static baz { 1 }
 }

test/language/constructor/default.wren

@@ -1,8 +0,0 @@
-class Foo {
-  toString { "Foo" }
-}
-
-// Classes get an argument-less "new()" by default.
-var foo = Foo.new()
-IO.print(foo is Foo) // expect: true
-IO.print(foo.toString) // expect: Foo

test/language/constructor/default_calls_new.wren

@@ -1,9 +0,0 @@
-class Foo {
-  construct new() {
-    IO.print("Foo.new()")
-  }
-}
-
-class Bar is Foo {}
-
-Bar.new() // expect: Foo.new()

test/language/constructor/no_default.wren

@@ -1,6 +1,4 @@
-class Foo {
-  construct real() {}
-}
+class Foo {}
 
-// Classes do not get an argument-less "new()" if they define a constructor.
+// Classes do not get a constructor by default.
 var foo = Foo.new() // expect runtime error: Foo metaclass does not implement 'new()'.

test/language/constructor/object.wren

@@ -1,11 +0,0 @@
-// Tests that Object implements new(). The only way to call that is through a
-// super() call in a subclass, so this does that.
-
-class Foo {
-  construct new() {
-    super() // Should not cause a no method error.
-    IO.print("ok")
-  }
-}
-
-Foo.new() // expect: ok

test/language/field/default_to_null.wren

@@ -1,4 +1,5 @@
 class Foo {
+  construct new() {}
   write { IO.print(_field) }
 }
 

test/language/field/multiple.wren

@@ -1,4 +1,6 @@
 class Foo {
+  construct new() {}
+
   set(a, b, c, d, e) {
     _a = a
     _b = b

test/language/field/nested_class.wren

@@ -1,9 +1,13 @@
 class Outer {
+  construct new() {}
+
   method {
     _field = "outer"
     IO.print(_field) // expect: outer
 
     class Inner {
+      construct new() {}
+
       method {
         _field = "inner"
         IO.print(_field) // expect: inner

test/language/field/use_before_set.wren

@@ -1,4 +1,5 @@
 class Foo {
+  construct new() {}
   write { IO.print(_field) } // Compile a use of the field...
   init { _field = "value" }  // ...before an assignment to it.
 }

test/language/implicit_receiver/inherited_methods.wren

@@ -1,4 +1,6 @@
 class Foo {
+  construct new() {}
+
   getter {
     IO.print("getter")
   }
@@ -13,6 +15,8 @@ class Foo {
 }
 
 class Bar is Foo {
+  construct new() {}
+
   test {
     getter            // expect: getter
     setter = "value"  // expect: setter

test/language/implicit_receiver/instance_methods.wren

@@ -1,4 +1,6 @@
 class Foo {
+  construct new() {}
+
   getter {
     IO.print("getter")
   }

test/language/implicit_receiver/locals_shadow_getter.wren

@@ -1,4 +1,6 @@
 class Foo {
+  construct new() {}
+
   bar { "getter" }
 
   test {

test/language/implicit_receiver/locals_shadow_setter.wren

@@ -1,4 +1,6 @@
 class Foo {
+  construct new() {}
+
   bar=(value) {
     IO.print("setter")
     return value

test/language/implicit_receiver/nested_class.wren

@@ -1,4 +1,6 @@
 class Outer {
+  construct new() {}
+
   getter {
     IO.print("outer getter")
   }
@@ -17,6 +19,8 @@ class Outer {
     method("arg")     // expect: outer method
 
     class Inner {
+      construct new() {}
+
       getter {
         IO.print("inner getter")
       }

test/language/inheritance/inherit_fields.wren

@@ -1,4 +1,6 @@
 class Foo {
+  construct new() {}
+
   foo(a, b) {
     _field1 = a
     _field2 = b
@@ -11,6 +13,8 @@ class Foo {
 }
 
 class Bar is Foo {
+  construct new() {}
+
   bar(a, b) {
     _field1 = a
     _field2 = b

test/language/inheritance/inherit_methods.wren

@@ -6,6 +6,7 @@ class Foo {
 }
 
 class Bar is Foo {
+  construct new() {}
   methodOnBar { IO.print("bar") }
   method(a, b) { IO.print("bar") }
   method(a, b, c, d) { IO.print("bar") }

test/language/inheritance/is.wren

@@ -1,6 +1,12 @@
-class A {}
-class B is A {}
-class C is B {}
+class A {
+  construct new() {}
+}
+class B is A {
+  construct new() {}
+}
+class C is B {
+  construct new() {}
+}
 var a = A.new()
 var b = B.new()
 var c = C.new()

test/language/method/arity.wren

@@ -1,4 +1,5 @@
 class Foo {
+  construct new() {}
   method { "getter" }
   method() { "no args" }
   method(a) { a }

test/language/method/empty_block.wren

@@ -1,4 +1,5 @@
 class Foo {
+  construct new() {}
   bar {}
 }
 

test/language/method/long_name.wren

@@ -1,4 +1,5 @@
 class Foo {
+  construct new() {}
   thisHasAMethodNameThatIsExactly64CharactersLongWhichIsTheMaximum {
     return "result"
   }

test/language/method/many_methods.wren

@@ -1,4 +1,5 @@
 class Foo {
+  construct new() {}
   method000 { 1 }
   method001 { 1 }
   method002 { 1 }

test/language/method/newlines.wren

@@ -1,4 +1,5 @@
 class Foo {
+  construct new() {}
   method(a, b) { "method " + a + " " + b }
   [a, b] { "subscript " + a + " " + b }
 }

test/language/method/not_found.wren

@@ -1,3 +1,5 @@
-class Foo {}
+class Foo {
+  construct new() {}
+}
 
 Foo.new().someUnknownMethod // expect runtime error: Foo does not implement 'someUnknownMethod'.

test/language/method/not_found_eleven_arguments.wren

@@ -1,3 +1,5 @@
-class Foo {}
+class Foo {
+  construct new() {}
+}
 
 Foo.new().someUnknownMethod(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11) // expect runtime error: Foo does not implement 'someUnknownMethod(_,_,_,_,_,_,_,_,_,_,_)'.

test/language/method/not_found_multiple_arguments.wren

@@ -1,3 +1,5 @@
-class Foo {}
+class Foo {
+  construct new() {}
+}
 
 Foo.new().someUnknownMethod(1, 2) // expect runtime error: Foo does not implement 'someUnknownMethod(_,_)'.

test/language/method/not_found_one_argument.wren

@@ -1,3 +1,5 @@
-class Foo {}
+class Foo {
+  construct new() {}
+}
 
 Foo.new().someUnknownMethod(1) // expect runtime error: Foo does not implement 'someUnknownMethod(_)'.

test/language/method/operators.wren

@@ -1,4 +1,6 @@
 class Foo {
+  construct new() {}
+
   +(other) { "infix + " + other }
   -(other) { "infix - " + other }
   *(other) { "infix * " + other }

test/language/method/static.wren

@@ -1,4 +1,5 @@
 class Foo {
+  construct new() {}
   bar { "on instance" }
   static bar { "on metaclass" }
 

test/language/method/subscript_operators.wren

@@ -1,4 +1,5 @@
 class Foo {
+  construct new() {}
   [a] { "1-subscript " + a }
   [a, b] { "2-subscript " + a + " " + b }
   [a, b, c] { "3-subscript " + a + " " + b + " " + c }

test/language/nonlocal/mutual_recursion.wren

@@ -1,8 +1,10 @@
 class Foo {
+  construct new() {}
   static bar { Bar.new() }
 }
 
 class Bar {
+  construct new() {}
   static foo { Foo.new() }
 }
 

test/language/nonlocal/use_in_method.wren

@@ -1,6 +1,8 @@
 var Global = "global"
 
 class Foo {
+  construct new() {}
+
   method {
     IO.print(Global)
   }

test/language/nonlocal/use_in_method_before_definition.wren

@@ -1,4 +1,6 @@
 class Foo {
+  construct new() {}
+
   method {
     IO.print(Global)
   }

test/language/return/in_method.wren

@@ -1,4 +1,6 @@
 class Foo {
+  construct new() {}
+
   method {
     return "ok"
     IO.print("bad")

test/language/setter/instance.wren

@@ -1,4 +1,6 @@
 class Foo {
+  construct new() {}
+
   bar=(value) {
     IO.print(value)
   }

test/language/setter/result.wren

@@ -1,4 +1,5 @@
 class Foo {
+  construct new() {}
   bar=(value) { "result" }
 }
 

test/language/setter/same_name_as_method.wren

@@ -1,4 +1,5 @@
 class Foo {
+  construct new() {}
   bar=(value) { IO.print("set") }
   bar { IO.print("get") }
 }

test/language/static_field/in_instance_method.wren

@@ -1,4 +1,6 @@
 class Foo {
+  construct new() {}
+
   set(a, b, c, d, e) {
     __a = a
     __b = b

test/language/static_field/nested_class.wren

@@ -1,9 +1,13 @@
 class Outer {
+  construct new() {}
+
   static staticMethod {
     __field = "outer"
     IO.print(__field) // expect: outer
 
     class Inner {
+      construct new() {}
+
       static staticMethod {
         __field = "inner"
         IO.print(__field) // expect: inner
@@ -19,6 +23,8 @@ class Outer {
     IO.print(__field) // expect: outer
 
     class Inner {
+      construct new() {}
+
       instanceMethod {
         __field = "inner"
         IO.print(__field) // expect: inner

test/language/super/call_different_arity.wren

@@ -5,6 +5,8 @@ class Base {
 }
 
 class Derived is Base {
+  construct new() {}
+
   foo(a) {
     IO.print("Derived.bar(a)")
     super

test/language/super/call_other_method.wren

@@ -5,6 +5,8 @@ class Base {
 }
 
 class Derived is Base {
+  construct new() {}
+
   bar {
     IO.print("Derived.bar")
     super.foo

test/language/super/call_same_method.wren

@@ -5,6 +5,8 @@ class Base {
 }
 
 class Derived is Base {
+  construct new() {}
+
   foo {
     IO.print("Derived.foo")
     super.foo

test/language/super/closure.wren

@@ -3,6 +3,7 @@ class Base {
 }
 
 class Derived is Base {
+  construct new() {}
   getClosure { Fn.new { super.toString } }
   toString { "Derived" }
 }

test/language/super/implicit_name.wren

@@ -5,6 +5,8 @@ class Base {
 }
 
 class Derived is Base {
+  construct new() {}
+
   foo {
     IO.print("Derived.foo")
     super

test/language/super/indirectly_inherited.wren

@@ -7,6 +7,8 @@ class A {
 class B is A {}
 
 class C is B {
+  construct new() {}
+
   foo {
     IO.print("C.foo")
     super.foo

test/language/super/no_superclass_method.wren

@@ -1,6 +1,7 @@
 class Base {}
 
 class Derived is Base {
+  construct new() {}
   foo { super.doesNotExist(1) } // expect runtime error: Base does not implement 'doesNotExist(_)'.
 }
 

test/language/super/super_in_closure_in_inherited_method.wren

@@ -6,6 +6,8 @@ class A {
   toString { "A.toString" }
 }
 
-class B is A {}
+class B is A {
+  construct new() {}
+}
 
 IO.print(B.new().callSuperToString) // expect: instance of B

test/language/super/super_in_inherited_method.wren

@@ -4,6 +4,8 @@ class A {
   toString { "A.toString" }
 }
 
-class B is A {}
+class B is A {
+  construct new() {}
+}
 
 IO.print(B.new().callSuperToString) // expect: instance of B

test/language/this/closure.wren

@@ -1,4 +1,5 @@
 class Foo {
+  construct new() {}
   getClosure { Fn.new { toString } }
   toString { "Foo" }
 }

test/language/this/nested_class.wren

@@ -1,4 +1,6 @@
 class Outer {
+  construct new() {}
+
   method {
     IO.print(this) // expect: Outer
 
@@ -6,6 +8,8 @@ class Outer {
       IO.print(this) // expect: Outer
 
       class Inner {
+        construct new() {}
+
         method {
           IO.print(this) // expect: Inner
         }

test/language/this/nested_closure.wren

@@ -1,4 +1,5 @@
 class Foo {
+  construct new() {}
   getClosure { Fn.new { Fn.new { Fn.new { toString } } } }
   toString { "Foo" }
 }

test/language/this/this_in_method.wren

@@ -1,4 +1,5 @@
 class Foo {
+  construct new() {}
   bar { this }
   baz { "baz" }
 }

test/language/variable/local_in_middle_of_block.wren

@@ -1,4 +1,6 @@
 class Foo {
+  construct new() {}
+
   bar {
     var a = "a"
     IO.print(a) // expect: a

test/language/variable/outside_method.wren

@@ -1,6 +1,8 @@
 var foo = "variable"
 
 class Foo {
+  construct new() {}
+
   foo { "method" }
 
   method {