Forbid callable references to members and extensions with empty LHS

This syntax is reserved to be likely used in the future as a shorthand for
"this::foo" where the resulting expression doesn't take the receiver as a
parameter but has "this" already bound to it

compiler/testData/codegen/boxInline/callableReference/classLevel2.2.kt

@@ -3,9 +3,9 @@ package test
 class A(val z: Int) {
     fun calc() = z
 
-    fun test() = call(A(z), ::calc)
+    fun test() = call(A(z), A::calc)
 }
 
 inline fun call(p: A, s: A.() -> Int): Int {
     return p.s()
-}
+}

compiler/testData/codegen/boxWithStdlib/callableReference/function/classMemberFromClass.kt

@@ -1,7 +1,7 @@
 class A {
     fun foo(k: Int) = k
 
-    fun result() = (::foo)(this, 111)
+    fun result() = (A::foo)(this, 111)
 }
 
 fun box(): String {

compiler/testData/codegen/boxWithStdlib/callableReference/function/classMemberFromExtension.kt

@@ -3,7 +3,7 @@ class A {
     fun k(k: Int) = k
 }
 
-fun A.foo() = (::o)(this) + (A::k)(this, 222)
+fun A.foo() = (A::o)(this) + (A::k)(this, 222)
 
 fun box(): String {
     val result = A().foo()

compiler/testData/codegen/boxWithStdlib/callableReference/function/extensionFromClass.kt

@@ -1,5 +1,5 @@
 class A {
-    fun result() = (::foo)(this, "OK")
+    fun result() = (A::foo)(this, "OK")
 }
 
 fun A.foo(x: String) = x

compiler/testData/codegen/boxWithStdlib/callableReference/function/innerConstructorFromClass.kt

@@ -4,7 +4,7 @@ class A {
         val k = 222
     }
     
-    fun result() = (A::Inner)(this).o + (::Inner)(this).k
+    fun result() = (A::Inner)(this).o + (A::Inner)(this).k
 }
 
 fun box(): String {

compiler/testData/codegen/boxWithStdlib/callableReference/function/innerConstructorFromExtension.kt

@@ -5,7 +5,7 @@ class A {
     }
 }
 
-fun A.foo() = (A::Inner)(this).o + (::Inner)(this).k
+fun A.foo() = (A::Inner)(this).o + (A::Inner)(this).k
 
 fun box(): String {
     val result = A().foo()

compiler/testData/codegen/boxWithStdlib/callableReference/function/privateClassMember.kt

@@ -1,7 +1,7 @@
 class A {
     private fun foo() = "OK"
 
-    fun bar() = (::foo)(this)
+    fun bar() = (A::foo)(this)
 }
 
 fun box() = A().bar()

compiler/testData/codegen/boxWithStdlib/callableReference/function/traitImplMethodWithClassReceiver.kt

@@ -4,7 +4,7 @@ interface T {
 
 class B : T {
     inner class C {
-        fun bar() = (::foo)(this@B)
+        fun bar() = (T::foo)(this@B)
     }
 }
 

compiler/testData/codegen/boxWithStdlib/callableReference/property/kt6870_privatePropertyReference.kt

@@ -4,8 +4,8 @@ class Test {
     public fun exec() {
         val t = object : Thread() {
             override fun run() {
-                ::iv.get(this@Test)
-                ::iv.set(this@Test, 2)
+                Test::iv.get(this@Test)
+                Test::iv.set(this@Test, 2)
             }
         }
         t.start()

compiler/testData/codegen/boxWithStdlib/reflection/properties/privateToThisAccessors.kt

@@ -1,3 +1,4 @@
+import kotlin.reflect.*
 import kotlin.reflect.jvm.*
 
 class K<in T : String> {
@@ -6,10 +7,10 @@ class K<in T : String> {
         set(value) {}
 
     fun run(): String {
-        val p = ::t
+        val p = K::class.memberProperties.single() as KMutableProperty1<K<String>, String>
         p.isAccessible = true
-        p.set(this, "" as T)
-        return p.get(this)
+        p.set(this as K<String>, "")
+        return p.get(this) as String
     }
 }
 

compiler/testData/diagnostics/tests/callableReference/emptyLhs.kt

@@ -0,0 +1,40 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION
+
+val topLevelVal = 1
+fun topLevelFun() = 2
+
+val A.extensionVal: Int get() = 3
+fun A.extensionFun(): Int = 4
+
+class A {
+    val memberVal = 5
+    fun memberFun() = 6
+
+    val ok1 = ::topLevelVal
+    val ok2 = ::topLevelFun
+
+    fun fail1() {
+        ::<!CALLABLE_REFERENCE_TO_MEMBER_OR_EXTENSION_WITH_EMPTY_LHS!>extensionVal<!>
+        ::<!CALLABLE_REFERENCE_TO_MEMBER_OR_EXTENSION_WITH_EMPTY_LHS!>extensionFun<!>
+    }
+
+    fun fail2() {
+        ::<!CALLABLE_REFERENCE_TO_MEMBER_OR_EXTENSION_WITH_EMPTY_LHS!>memberVal<!>
+        ::<!CALLABLE_REFERENCE_TO_MEMBER_OR_EXTENSION_WITH_EMPTY_LHS!>memberFun<!>
+    }
+}
+
+
+
+val ok1 = ::topLevelVal
+val ok2 = ::topLevelFun
+
+fun A.fail1() {
+    ::<!CALLABLE_REFERENCE_TO_MEMBER_OR_EXTENSION_WITH_EMPTY_LHS!>extensionVal<!>
+    ::<!CALLABLE_REFERENCE_TO_MEMBER_OR_EXTENSION_WITH_EMPTY_LHS!>extensionFun<!>
+}
+
+fun A.fail2() {
+    ::<!CALLABLE_REFERENCE_TO_MEMBER_OR_EXTENSION_WITH_EMPTY_LHS!>memberVal<!>
+    ::<!CALLABLE_REFERENCE_TO_MEMBER_OR_EXTENSION_WITH_EMPTY_LHS!>memberFun<!>
+}

compiler/testData/diagnostics/tests/callableReference/emptyLhs.txt

@@ -0,0 +1,23 @@
+package
+
+public val ok1: kotlin.reflect.KProperty0<kotlin.Int>
+public val ok2: kotlin.reflect.KFunction0<kotlin.Int>
+public val topLevelVal: kotlin.Int = 1
+public val A.extensionVal: kotlin.Int
+public fun topLevelFun(): kotlin.Int
+public fun A.extensionFun(): kotlin.Int
+public fun A.fail1(): kotlin.Unit
+public fun A.fail2(): kotlin.Unit
+
+public final class A {
+    public constructor A()
+    public final val memberVal: kotlin.Int = 5
+    public final val ok1: kotlin.reflect.KProperty0<kotlin.Int>
+    public final val ok2: kotlin.reflect.KFunction0<kotlin.Int>
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public final fun fail1(): kotlin.Unit
+    public final fun fail2(): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public final fun memberFun(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}

compiler/testData/diagnostics/tests/callableReference/function/extensionFromClass.kt

@@ -1,19 +0,0 @@
-// !CHECK_TYPE
-
-import kotlin.reflect.*
-
-class A {
-    fun main() {
-        val x = ::foo
-        val y = ::bar
-        val z = ::baz
-
-        checkSubtype<KFunction1<A, Unit>>(x)
-        checkSubtype<KFunction2<A, Int, Unit>>(y)
-        checkSubtype<KFunction1<A, String>>(z)
-    }
-}
-
-fun A.foo() {}
-fun A.bar(<!UNUSED_PARAMETER!>x<!>: Int) {}
-fun A.baz() = "OK"

compiler/testData/diagnostics/tests/callableReference/function/extensionFromClass.txt

@@ -1,13 +0,0 @@
-package
-
-public fun A.bar(/*0*/ x: kotlin.Int): kotlin.Unit
-public fun A.baz(): kotlin.String
-public fun A.foo(): kotlin.Unit
-
-public final class A {
-    public constructor A()
-    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
-    public final fun main(): kotlin.Unit
-    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
-}

compiler/testData/diagnostics/tests/callableReference/function/extensionFromExtension.kt

@@ -1,19 +0,0 @@
-// !CHECK_TYPE
-
-import kotlin.reflect.*
-
-class A
-
-fun A.main() {
-    val x = ::foo
-    val y = ::bar
-    val z = ::baz
-
-    checkSubtype<KFunction1<A, Unit>>(x)
-    checkSubtype<KFunction2<A, Int, Unit>>(y)
-    checkSubtype<KFunction1<A, String>>(z)
-}
-
-fun A.foo() {}
-fun A.bar(<!UNUSED_PARAMETER!>x<!>: Int) {}
-fun A.baz() = "OK"

compiler/testData/diagnostics/tests/callableReference/function/extensionFromExtension.txt

@@ -1,13 +0,0 @@
-package
-
-public fun A.bar(/*0*/ x: kotlin.Int): kotlin.Unit
-public fun A.baz(): kotlin.String
-public fun A.foo(): kotlin.Unit
-public fun A.main(): kotlin.Unit
-
-public final class A {
-    public constructor A()
-    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
-    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
-}

compiler/testData/diagnostics/tests/callableReference/function/extensionFromExtensionInClass.kt

@@ -1,21 +0,0 @@
-// !CHECK_TYPE
-
-import kotlin.reflect.*
-
-class B
-
-class A {
-    fun B.main() {
-        val x = ::foo
-        val y = ::bar
-        val z = ::baz
-
-        checkSubtype<KFunction1<A, Unit>>(x)
-        checkSubtype<KFunction2<A, Int, Unit>>(y)
-        checkSubtype<KFunction1<A, String>>(z)
-    }
-}
-
-fun A.foo() {}
-fun A.bar(<!UNUSED_PARAMETER!>x<!>: Int) {}
-fun A.baz() = "OK"

compiler/testData/diagnostics/tests/callableReference/function/extensionFromExtensionInClass.txt

@@ -1,20 +0,0 @@
-package
-
-public fun A.bar(/*0*/ x: kotlin.Int): kotlin.Unit
-public fun A.baz(): kotlin.String
-public fun A.foo(): kotlin.Unit
-
-public final class A {
-    public constructor A()
-    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
-    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
-    public final fun B.main(): kotlin.Unit
-}
-
-public final class B {
-    public constructor B()
-    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
-    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
-}

compiler/testData/diagnostics/tests/callableReference/function/extensionInClassDisallowed.kt

@@ -4,8 +4,8 @@ class A {
     fun A.extA(x: String) = x
     
     fun main() {
-        ::<!MISSING_RECEIVER, EXTENSION_IN_CLASS_REFERENCE_NOT_ALLOWED!>extInt<!>
-        ::<!EXTENSION_IN_CLASS_REFERENCE_NOT_ALLOWED!>extA<!>
+        Int::<!EXTENSION_IN_CLASS_REFERENCE_NOT_ALLOWED!>extInt<!>
+        A::<!EXTENSION_IN_CLASS_REFERENCE_NOT_ALLOWED!>extA<!>
     }
 }
 

compiler/testData/diagnostics/tests/callableReference/function/innerConstructorFromClass.kt

@@ -6,10 +6,9 @@ class A {
     inner class Inner
     
     fun main() {
-        val x = ::Inner
+        ::<!CALLABLE_REFERENCE_TO_MEMBER_OR_EXTENSION_WITH_EMPTY_LHS!>Inner<!>
         val y = A::Inner
 
-        checkSubtype<KFunction1<A, A.Inner>>(x)
         checkSubtype<KFunction1<A, Inner>>(y)
     }
     

compiler/testData/diagnostics/tests/callableReference/function/innerConstructorFromExtension.kt

@@ -7,10 +7,9 @@ class A {
 }
     
 fun A.main() {
-    val x = ::Inner
+    ::<!CALLABLE_REFERENCE_TO_MEMBER_OR_EXTENSION_WITH_EMPTY_LHS!>Inner<!>
     val y = A::Inner
 
-    checkSubtype<KFunction1<A, A.Inner>>(x)
     checkSubtype<KFunction1<A, A.Inner>>(y)
 }
 

compiler/testData/diagnostics/tests/callableReference/function/memberFromClass.kt

@@ -1,19 +0,0 @@
-// !CHECK_TYPE
-
-import kotlin.reflect.*
-
-class A {
-    fun foo() {}
-    fun bar(<!UNUSED_PARAMETER!>x<!>: Int) {}
-    fun baz() = "OK"
-    
-    fun main() {
-        val x = ::foo
-        val y = ::bar
-        val z = ::baz
-
-        checkSubtype<KFunction1<A, Unit>>(x)
-        checkSubtype<KFunction2<A, Int, Unit>>(y)
-        checkSubtype<KFunction1<A, String>>(z)
-    }
-}

compiler/testData/diagnostics/tests/callableReference/function/memberFromClass.txt

@@ -1,12 +0,0 @@
-package
-
-public final class A {
-    public constructor A()
-    public final fun bar(/*0*/ x: kotlin.Int): kotlin.Unit
-    public final fun baz(): kotlin.String
-    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
-    public final fun foo(): kotlin.Unit
-    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
-    public final fun main(): kotlin.Unit
-    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
-}

compiler/testData/diagnostics/tests/callableReference/function/memberFromExtension.kt

@@ -1,19 +0,0 @@
-// !CHECK_TYPE
-
-import kotlin.reflect.*
-
-class A {
-    fun foo() {}
-    fun bar(<!UNUSED_PARAMETER!>x<!>: Int) {}
-    fun baz() = "OK"
-}
-    
-fun A.main() {
-    val x = ::foo
-    val y = ::bar
-    val z = ::baz
-
-    checkSubtype<KFunction1<A, Unit>>(x)
-    checkSubtype<KFunction2<A, Int, Unit>>(y)
-    checkSubtype<KFunction1<A, String>>(z)
-}

compiler/testData/diagnostics/tests/callableReference/function/memberFromExtension.txt

@@ -1,13 +0,0 @@
-package
-
-public fun A.main(): kotlin.Unit
-
-public final class A {
-    public constructor A()
-    public final fun bar(/*0*/ x: kotlin.Int): kotlin.Unit
-    public final fun baz(): kotlin.String
-    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
-    public final fun foo(): kotlin.Unit
-    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
-    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
-}

compiler/testData/diagnostics/tests/callableReference/function/memberFromExtensionInClass.kt

@@ -1,21 +0,0 @@
-// !CHECK_TYPE
-
-import kotlin.reflect.*
-
-class A {
-    fun foo() {}
-    fun bar(<!UNUSED_PARAMETER!>x<!>: Int) {}
-    fun baz() = "OK"
-}
-
-class B {
-    fun A.main() {
-        val x = ::foo
-        val y = ::bar
-        val z = ::baz
-
-        checkSubtype<KFunction1<A, Unit>>(x)
-        checkSubtype<KFunction2<A, Int, Unit>>(y)
-        checkSubtype<KFunction1<A, String>>(z)
-    }
-}

compiler/testData/diagnostics/tests/callableReference/function/memberFromExtensionInClass.txt

@@ -1,19 +0,0 @@
-package
-
-public final class A {
-    public constructor A()
-    public final fun bar(/*0*/ x: kotlin.Int): kotlin.Unit
-    public final fun baz(): kotlin.String
-    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
-    public final fun foo(): kotlin.Unit
-    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
-    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
-}
-
-public final class B {
-    public constructor B()
-    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
-    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
-    public final fun A.main(): kotlin.Unit
-}

compiler/testData/diagnostics/tests/callableReference/function/noAmbiguityMemberVsTopLevel.kt

@@ -8,7 +8,7 @@ class A {
     fun foo() {}
     
     fun main() {
-        val x = ::foo
+        val x = ::<!CALLABLE_REFERENCE_TO_MEMBER_OR_EXTENSION_WITH_EMPTY_LHS!>foo<!>
 
         checkSubtype<KFunction1<A, Unit>>(x)
     }

compiler/testData/diagnostics/tests/callableReference/property/classFromClass.kt

@@ -6,7 +6,7 @@ class A(var g: A) {
     val f: Int = 0
 
     fun test() {
-        val fRef: KProperty1<A, Int> = ::f
-        val gRef: KMutableProperty1<A, A> = ::g
+        val fRef: KProperty1<A, Int> = A::f
+        val gRef: KMutableProperty1<A, A> = A::g
     }
 }

compiler/testData/diagnostics/tests/callableReference/property/extensionFromClass.kt

@@ -1,15 +0,0 @@
-// !DIAGNOSTICS:-UNUSED_VARIABLE
-
-import kotlin.reflect.*
-
-class A {
-    fun test() {
-        val fooRef: KProperty1<A, String> = ::foo
-        val barRef: KMutableProperty1<A, Int> = ::bar
-    }
-}
-
-val A.foo: String get() = ""
-var A.bar: Int
-    get() = 42
-    set(value) { }

compiler/testData/diagnostics/tests/callableReference/property/extensionFromClass.txt

@@ -1,12 +0,0 @@
-package
-
-public var A.bar: kotlin.Int
-public val A.foo: kotlin.String
-
-public final class A {
-    public constructor A()
-    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
-    public final fun test(): kotlin.Unit
-    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
-}

compiler/testData/diagnostics/tests/callableReference/property/kt7564.kt

@@ -6,7 +6,7 @@ class A(var g: A) {
     val f: Int = 0
 
     fun test() {
-        checkSubtype<KProperty1<A, Int>>(::f)
-        checkSubtype<KMutableProperty1<A, A>>(::g)
+        checkSubtype<KProperty1<A, Int>>(A::f)
+        checkSubtype<KMutableProperty1<A, A>>(A::g)
     }
 }

compiler/testData/diagnostics/tests/callableReference/property/memberFromExtension.kt

@@ -1,23 +0,0 @@
-// !CHECK_TYPE
-
-import kotlin.reflect.*
-
-class A {
-    val foo: Unit = Unit
-    var bar: String = ""
-    var self: A
-        get() = this
-        set(value) { }
-}
-    
-fun A.test() {
-    val x = ::foo
-    val y = ::bar
-    val z = ::self
-
-    checkSubtype<KProperty1<A, Unit>>(x)
-    checkSubtype<KMutableProperty1<A, String>>(y)
-    checkSubtype<KMutableProperty1<A, A>>(z)
-
-    y.set(z.get(A()), x.get(A()).toString())
-}

compiler/testData/diagnostics/tests/callableReference/property/memberFromExtension.txt

@@ -1,13 +0,0 @@
-package
-
-public fun A.test(): kotlin.Unit
-
-public final class A {
-    public constructor A()
-    public final var bar: kotlin.String
-    public final val foo: kotlin.Unit
-    public final var self: A
-    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
-    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
-}

compiler/testData/repl/reflection/propertyReference.repl

@@ -1,6 +0,0 @@
->>> val foo = "REPL"
->>> ::foo.name
-foo
->>> ::
-... foo.name
-foo