Change behavior of equals/hashCode on adapted function references

Function references are now equal if they refer to the same function,
and if the parameter/return type adaptation, which happens when a
reference is used where some function type is expected, is exactly the
same. This includes the number of expected positional parameters (which
can be affected by defaults/varargs), whether the coercion of vararg
parameter to Array type happened, and whether the coercion of return
type to Unit happened.

 #KT-37543 Fixed

compiler/testData/codegen/box/callableReference/equality/capturedDefaults.kt

@@ -0,0 +1,64 @@
+// IGNORE_BACKEND: JVM_IR, JS, JS_IR, NATIVE
+// IGNORE_BACKEND_FIR: JVM_IR
+// FILE: test.kt
+
+fun checkEqual(x: Any, y: Any) {
+    if (x != y || y != x) throw AssertionError("$x and $y should be equal")
+    if (x.hashCode() != y.hashCode()) throw AssertionError("$x and $y should have the same hash code")
+}
+
+fun checkNotEqual(x: Any, y: Any) {
+    if (x == y || y == x) throw AssertionError("$x and $y should NOT be equal")
+}
+
+class V {
+    fun target(x: String = "x", y: String = "y", z: String = "z"): String = x + y + z
+}
+
+private fun captureNoDefaults(f: (V, String, String, String) -> String): Any = f
+private fun captureOneDefault(f: (V, String, String) -> String): Any = f
+private fun captureAllDefaults(f: (V) -> String): Any = f
+
+private fun captureNoDefaultsBound(f: (String, String, String) -> String): Any = f
+private fun captureOneDefaultBound(f: (String, String) -> String): Any = f
+private fun captureAllDefaultsBound(f: () -> String): Any = f
+
+fun box(): String {
+    val v0 = V()
+
+    checkEqual(captureNoDefaults(V::target), captureNoDefaults(V::target))
+    checkEqual(captureNoDefaults(V::target), captureNoDefaultsFromOtherFile())
+
+    checkEqual(captureOneDefault(V::target), captureOneDefault(V::target))
+    checkEqual(captureOneDefault(V::target), captureOneDefaultFromOtherFile())
+
+    checkEqual(captureAllDefaults(V::target), captureAllDefaults(V::target))
+
+    checkEqual(captureNoDefaultsBound(v0::target), captureNoDefaultsBound(v0::target))
+    checkEqual(captureNoDefaultsBound(v0::target), captureNoDefaultsBoundFromOtherFile(v0))
+
+    checkEqual(captureOneDefaultBound(v0::target), captureOneDefaultBound(v0::target))
+
+    checkEqual(captureAllDefaultsBound(v0::target), captureAllDefaultsBound(v0::target))
+
+
+    checkNotEqual(captureNoDefaults(V::target), captureOneDefault(V::target))
+    checkNotEqual(captureNoDefaults(V::target), captureAllDefaults(V::target))
+
+    checkNotEqual(captureNoDefaultsBound(v0::target), captureOneDefaultBound(v0::target))
+    checkNotEqual(captureNoDefaultsBound(v0::target), captureAllDefaultsBound(v0::target))
+
+    checkNotEqual(captureNoDefaults(V::target), captureNoDefaultsBoundFromOtherFile(v0))
+
+    return "OK"
+}
+
+// FILE: fromOtherFile.kt
+
+private fun captureNoDefaults(f: (V, String, String, String) -> String): Any = f
+private fun captureOneDefault(f: (V, String, String) -> String): Any = f
+private fun captureNoDefaultsBound(f: (String, String, String) -> String): Any = f
+
+fun captureNoDefaultsFromOtherFile(): Any = captureNoDefaults(V::target)
+fun captureOneDefaultFromOtherFile(): Any = captureOneDefault(V::target)
+fun captureNoDefaultsBoundFromOtherFile(v0: V) = captureNoDefaultsBound(v0::target)