Improve diagnostics on callable reference of unresolved class

#KT-10839 Fixed

compiler/frontend/src/org/jetbrains/kotlin/types/expressions/DoubleColonExpressionResolver.kt

@@ -528,7 +528,9 @@ class DoubleColonExpressionResolver(
                     resolvedCall?.resultingDescriptor ?: return null
                 }
                 else {
-                    context.trace.report(UNRESOLVED_REFERENCE.on(expression.callableReference, expression.callableReference))
+                    if (lhs != null || expression.isEmptyLHS) {
+                        context.trace.report(UNRESOLVED_REFERENCE.on(expression.callableReference, expression.callableReference))
+                    }
                     return null
                 }
 
@@ -680,10 +682,13 @@ class DoubleColonExpressionResolver(
     ): OverloadResolutionResults<CallableDescriptor>? {
         val reference = expression.callableReference
 
-        val lhsType =
+        val lhsType = lhs?.type
-                lhs?.type ?:
+        if (lhsType == null) {
-                return tryResolveRHSWithReceiver("resolve callable reference with empty LHS", null, reference, c, mode)
+            if (!expression.isEmptyLHS) return null
+
+            return tryResolveRHSWithReceiver("resolve callable reference with empty LHS", null, reference, c, mode)
                        ?.apply { commitTrace() }?.results
+        }
 
         val resultSequence = buildSequence {
             when (lhs) {

compiler/testData/diagnostics/tests/callableReference/bound/kt12843.kt

@@ -1,6 +1,6 @@
 class Foo {
     fun bar() {}
-    fun f() = <!UNRESOLVED_REFERENCE!>Unresolved<!>()::bar
+    fun f() = <!UNRESOLVED_REFERENCE!>Unresolved<!>()::<!DEBUG_INFO_MISSING_UNRESOLVED!>bar<!>
 }
 
-val f: () -> Unit = <!UNRESOLVED_REFERENCE!>Unresolved<!>()::<!UNRESOLVED_REFERENCE!>foo<!>
+val f: () -> Unit = <!UNRESOLVED_REFERENCE!>Unresolved<!>()::<!DEBUG_INFO_MISSING_UNRESOLVED!>foo<!>

compiler/testData/diagnostics/tests/callableReference/bound/kt12843.txt

@@ -6,7 +6,7 @@ public final class Foo {
     public constructor Foo()
     public final fun bar(): kotlin.Unit
     public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
-    public final fun f(): kotlin.reflect.KFunction0<kotlin.Unit>
+    public final fun f(): [ERROR : Error function type]
     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/bound/reservedExpressionSyntax.kt

@@ -26,8 +26,8 @@ class Test {
     fun <T> List<T>.testClassLiteral2() = <!RESERVED_SYNTAX_IN_CALLABLE_REFERENCE_LHS, EXPRESSION_OF_NULLABLE_TYPE_IN_CLASS_LITERAL_LHS!>b<!>?::class
     fun <T> List<T>.testClassLiteral3() = <!RESERVED_SYNTAX_IN_CALLABLE_REFERENCE_LHS, EXPRESSION_OF_NULLABLE_TYPE_IN_CLASS_LITERAL_LHS!>b<T, Any><!>::class
 
-    fun <T> List<T>.testUnresolved1() = <!UNRESOLVED_REFERENCE!>unresolved<!><T>::<!UNRESOLVED_REFERENCE_WRONG_RECEIVER!>foo<!>
+    fun <T> List<T>.testUnresolved1() = <!UNRESOLVED_REFERENCE!>unresolved<!><T>::<!DEBUG_INFO_MISSING_UNRESOLVED!>foo<!>
     fun <T> List<T>.testUnresolved2() = <!RESERVED_SYNTAX_IN_CALLABLE_REFERENCE_LHS!>a<<!UNRESOLVED_REFERENCE!>unresolved<!>><!>::foo
     fun <T> List<T>.testUnresolved3() = a<<!SYNTAX!><!>>::foo
-    fun <T> List<T>.testUnresolved4() = <!UNRESOLVED_REFERENCE!>unresolved<!>?::<!UNRESOLVED_REFERENCE_WRONG_RECEIVER!>foo<!>
+    fun <T> List<T>.testUnresolved4() = <!UNRESOLVED_REFERENCE!>unresolved<!>?::<!DEBUG_INFO_MISSING_UNRESOLVED!>foo<!>
 }

compiler/testData/diagnostics/tests/callableReference/bound/reservedExpressionSyntax3.kt

@@ -21,8 +21,8 @@ class Test {
 
     val Int.c: Int get() = 42
 
-    val test1: () -> Right = <!RESERVED_SYNTAX_IN_CALLABLE_REFERENCE_LHS!><!DEBUG_INFO_MISSING_UNRESOLVED!>a<!>.<!DEBUG_INFO_MISSING_UNRESOLVED!>b<!><<!DEBUG_INFO_MISSING_UNRESOLVED!>Int<!>>.<!DEBUG_INFO_MISSING_UNRESOLVED!>c<!><!>::<!UNRESOLVED_REFERENCE_WRONG_RECEIVER!>foo<!>
+    val test1: () -> Right = <!RESERVED_SYNTAX_IN_CALLABLE_REFERENCE_LHS!><!DEBUG_INFO_MISSING_UNRESOLVED!>a<!>.<!DEBUG_INFO_MISSING_UNRESOLVED!>b<!><<!DEBUG_INFO_MISSING_UNRESOLVED!>Int<!>>.<!DEBUG_INFO_MISSING_UNRESOLVED!>c<!><!>::<!DEBUG_INFO_MISSING_UNRESOLVED!>foo<!>
     val test1a: () -> Right = a.b.c::foo
 
-    val test2: () -> Right = <!RESERVED_SYNTAX_IN_CALLABLE_REFERENCE_LHS!><!DEBUG_INFO_MISSING_UNRESOLVED!>a<!>.<!DEBUG_INFO_MISSING_UNRESOLVED!>b<!><<!DEBUG_INFO_MISSING_UNRESOLVED!>Int<!>>.<!DEBUG_INFO_MISSING_UNRESOLVED!>c<!><!>?::<!UNRESOLVED_REFERENCE_WRONG_RECEIVER!>foo<!>
+    val test2: () -> Right = <!RESERVED_SYNTAX_IN_CALLABLE_REFERENCE_LHS!><!DEBUG_INFO_MISSING_UNRESOLVED!>a<!>.<!DEBUG_INFO_MISSING_UNRESOLVED!>b<!><<!DEBUG_INFO_MISSING_UNRESOLVED!>Int<!>>.<!DEBUG_INFO_MISSING_UNRESOLVED!>c<!><!>?::<!DEBUG_INFO_MISSING_UNRESOLVED!>foo<!>
 }

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

@@ -1,12 +1,22 @@
-// !DIAGNOSTICS: -UNUSED_EXPRESSION
+// !DIAGNOSTICS: -UNUSED_EXPRESSION, -UNUSED_PARAMETER
 class A
 
-fun main() {
+fun test1() {
     val <!UNUSED_VARIABLE!>foo<!> = ::<!UNRESOLVED_REFERENCE!>foo<!>
-    
+
     ::<!UNRESOLVED_REFERENCE!>bar<!>
-    
+
     A::<!UNRESOLVED_REFERENCE!>bar<!>
-    
+
-    <!UNRESOLVED_REFERENCE!>B<!>::<!UNRESOLVED_REFERENCE!>bar<!>
+    <!UNRESOLVED_REFERENCE!>B<!>::<!DEBUG_INFO_MISSING_UNRESOLVED!>bar<!>
 }
+
+fun test2() {
+    fun foo(x: Any) {}
+    fun foo() {}
+
+    <!UNRESOLVED_REFERENCE!>Unresolved<!>::<!DEBUG_INFO_MISSING_UNRESOLVED!>foo<!>
+    foo(<!UNRESOLVED_REFERENCE!>Unresolved<!>::<!DEBUG_INFO_MISSING_UNRESOLVED!>foo<!>)
+    foo(<!UNRESOLVED_REFERENCE!>Unresolved<!>::<!DEBUG_INFO_MISSING_UNRESOLVED!>unresolved<!>)
+    ::<!UNRESOLVED_REFERENCE!>unresolved<!>
+}

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

@@ -1,6 +1,7 @@
 package
 
-public fun main(): kotlin.Unit
+public fun test1(): kotlin.Unit
+public fun test2(): kotlin.Unit
 
 public final class A {
     public constructor A()

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

@@ -4,7 +4,7 @@
 package foo
 
 fun test() {
-    <!EXPRESSION_EXPECTED_PACKAGE_FOUND!>foo<!>::test
+    <!EXPRESSION_EXPECTED_PACKAGE_FOUND!>foo<!>::<!DEBUG_INFO_MISSING_UNRESOLVED!>test<!>
 }
 
 // FILE: qualifiedName.kt
@@ -12,5 +12,5 @@ fun test() {
 package foo.bar
 
 fun test() {
-    foo.<!EXPRESSION_EXPECTED_PACKAGE_FOUND!>bar<!>::test
+    foo.<!EXPRESSION_EXPECTED_PACKAGE_FOUND!>bar<!>::<!DEBUG_INFO_MISSING_UNRESOLVED!>test<!>
 }

compiler/testData/diagnostics/tests/incompleteCode/illegalSelectorCallableReference.kt

@@ -1,8 +1,8 @@
 // !DIAGNOSTICS: -UNUSED_EXPRESSION
 
 fun test() {
-    "a".<!ILLEGAL_SELECTOR!>"b"<!>::<!UNRESOLVED_REFERENCE!>foo<!>
+    "a".<!ILLEGAL_SELECTOR!>"b"<!>::<!DEBUG_INFO_MISSING_UNRESOLVED!>foo<!>
     "a".<!ILLEGAL_SELECTOR!>"b"<!>::class
-    "a".<!ILLEGAL_SELECTOR!>"b"<!>.<!ILLEGAL_SELECTOR!>"c"<!>::<!UNRESOLVED_REFERENCE!>foo<!>
+    "a".<!ILLEGAL_SELECTOR!>"b"<!>.<!ILLEGAL_SELECTOR!>"c"<!>::<!DEBUG_INFO_MISSING_UNRESOLVED!>foo<!>
     "a".<!ILLEGAL_SELECTOR!>"b"<!>.<!ILLEGAL_SELECTOR!>"c"<!>::class
 }

compiler/testData/diagnostics/tests/qualifiedExpression/calleeExpressionAsCallExpression.kt

@@ -1 +1 @@
-val unwrapped = <!UNRESOLVED_REFERENCE!>some<!><!DEBUG_INFO_ELEMENT_WITH_ERROR_TYPE!><<!><!DEBUG_INFO_MISSING_UNRESOLVED!>sdf<!>()()<out <!DEBUG_INFO_MISSING_UNRESOLVED!>Any<!>>::<!UNRESOLVED_REFERENCE!>unwrap<!>
+val unwrapped = <!UNRESOLVED_REFERENCE!>some<!><!DEBUG_INFO_ELEMENT_WITH_ERROR_TYPE!><<!><!DEBUG_INFO_MISSING_UNRESOLVED!>sdf<!>()()<out <!DEBUG_INFO_MISSING_UNRESOLVED!>Any<!>>::<!DEBUG_INFO_MISSING_UNRESOLVED!>unwrap<!>

compiler/testData/diagnostics/tests/qualifiedExpression/nullCalleeExpression.kt

@@ -1 +1 @@
-val unwrapped = <!UNRESOLVED_REFERENCE!>some<!>.<!SYNTAX!><<!><!DEBUG_INFO_ELEMENT_WITH_ERROR_TYPE!>cabc<!><!SYNTAX!>$Wrapper<!><out <!DEBUG_INFO_MISSING_UNRESOLVED!>Any<!>>::<!UNRESOLVED_REFERENCE!>unwrap<!>
+val unwrapped = <!UNRESOLVED_REFERENCE!>some<!>.<!SYNTAX!><<!><!DEBUG_INFO_ELEMENT_WITH_ERROR_TYPE!>cabc<!><!SYNTAX!>$Wrapper<!><out <!DEBUG_INFO_MISSING_UNRESOLVED!>Any<!>>::<!DEBUG_INFO_MISSING_UNRESOLVED!>unwrap<!>

compiler/testData/diagnostics/tests/regressions/kt13685.kt

@@ -2,5 +2,5 @@
 
 fun foo() {
     val <!UNUSED_VARIABLE!>text<!>: List<Any> = null!!
-    text.<!UNRESOLVED_REFERENCE!>map<!> <!DEBUG_INFO_ELEMENT_WITH_ERROR_TYPE!>Any<!><!SYNTAX!>?<!>::<!UNRESOLVED_REFERENCE!>toString<!>
+    text.<!UNRESOLVED_REFERENCE!>map<!> <!DEBUG_INFO_ELEMENT_WITH_ERROR_TYPE!>Any<!><!SYNTAX!>?<!>::<!DEBUG_INFO_MISSING_UNRESOLVED!>toString<!>
 }