[PSI, FE] Support functional types

compiler/testData/diagnostics/tests/extensions/contextReceivers/fromKEEP/clickHandler.kt

@@ -0,0 +1,10 @@
+// FIR_IDENTICAL
+
+class Button
+class ClickEvent
+
+typealias ClickHandler = context(Button) (ClickEvent) -> Unit
+
+fun handleClick(clickHandler: ClickHandler) {
+    clickHandler(Button(), ClickEvent())
+}

compiler/testData/diagnostics/tests/extensions/contextReceivers/fromKEEP/clickHandler.txt

@@ -0,0 +1,18 @@
+package
+
+public fun handleClick(/*0*/ clickHandler: ClickHandler /* = @kotlin.ContextFunctionTypeParams(count = 1) (ClickEvent) -> kotlin.Unit */): kotlin.Unit
+
+public final class Button {
+    public constructor Button()
+    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 class ClickEvent {
+    public constructor ClickEvent()
+    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 typealias ClickHandler = @kotlin.ContextFunctionTypeParams(count = 1) (ClickEvent) -> kotlin.Unit

compiler/testData/diagnostics/tests/extensions/contextReceivers/fromKEEP/functionalType.fir.kt

@@ -0,0 +1,21 @@
+// !LANGUAGE: +ContextReceivers
+// !DIAGNOSTICS: -ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE
+
+class Context
+class Receiver
+class Param
+
+fun foo(context: Context, receiver: Receiver, p: Param) {}
+
+context(Context)
+fun bar(receiver: Receiver, p: Param) {}
+
+context(Context)
+fun Receiver.baz(p: Param) {}
+
+fun main() {
+    var g: context(Context) Receiver.(Param) -> Unit
+    g = ::<!UNRESOLVED_REFERENCE!>foo<!>         // OK
+    g = ::bar         // OK
+    g = Receiver::baz // OK
+}

compiler/testData/diagnostics/tests/extensions/contextReceivers/fromKEEP/functionalType.kt

@@ -0,0 +1,20 @@
+// !DIAGNOSTICS: -ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE
+
+class Context
+class Receiver
+class Param
+
+fun foo(context: Context, receiver: Receiver, p: Param) {}
+
+context(Context)
+fun bar(receiver: Receiver, p: Param) {}
+
+context(Context)
+fun Receiver.baz(p: Param) {}
+
+fun main() {
+    var g: context(Context) Receiver.(Param) -> Unit
+    g = ::foo         // OK
+    g = ::bar         // OK
+    g = Receiver::baz // OK
+}

compiler/testData/diagnostics/tests/extensions/contextReceivers/fromKEEP/functionalType.txt

@@ -0,0 +1,27 @@
+package
+
+public fun bar(/*0*/ receiver: Receiver, /*1*/ p: Param): kotlin.Unit
+public fun foo(/*0*/ context: Context, /*1*/ receiver: Receiver, /*2*/ p: Param): kotlin.Unit
+public fun main(): kotlin.Unit
+public fun Receiver.baz(/*0*/ p: Param): kotlin.Unit
+
+public final class Context {
+    public constructor Context()
+    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 class Param {
+    public constructor Param()
+    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 class Receiver {
+    public constructor Receiver()
+    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
+}