JVM_IR KT-47939 equality for fun interface constructor references

compiler/testData/codegen/box/callableReference/funInterfaceConstructor/funInterfaceConstructedObjectsEquality.kt

@@ -0,0 +1,43 @@
+// !LANGUAGE: +AllowKotlinFunInterfaceConstructorReference
+
+// IGNORE_BACKEND: JVM
+//  ^ unsupported in old JVM BE
+
+// IGNORE_BACKEND: WASM
+//  ^ wasm-function[1893]:0x1cf8a: RuntimeError: dereferencing a null pointer
+
+// IGNORE_BACKEND: JS_IR
+//  ^ TypeError: tmp is not a function
+
+// FILE: funInterfaceConstructorEquality.kt
+
+val ks1: (() -> String) -> KSupplier<String> =
+    ::KSupplier
+
+val ks11Foo = ks1(::foo)
+val ks21Foo = ks2(::foo)
+
+fun box(): String {
+    if (ks11Foo != ks12Foo)
+        return "failed: ks11Foo != ks12Foo (same ctor, different source files)"
+    if (ks11Foo != ks21Foo)
+        return "failed: ks11Foo != ks21Foo (different ctors, same source file)"
+    if (ks11Foo != ks22Foo)
+        return "failed: ks11Foo != ks22Foo (different ctors, different source files)"
+
+    return "OK"
+}
+
+// FILE: KSupplier.kt
+
+fun interface KSupplier<T> {
+    fun get(): T
+}
+
+fun foo() = "abc"
+
+val ks2: (() -> String) -> KSupplier<String> =
+    ::KSupplier
+
+val ks12Foo = ks1(::foo)
+val ks22Foo = ks2(::foo)

compiler/testData/codegen/box/callableReference/funInterfaceConstructor/funInterfaceConstructor.kt

@@ -1,6 +1,7 @@
 // !LANGUAGE: +AllowKotlinFunInterfaceConstructorReference
+
 // IGNORE_BACKEND: JVM
-//  ^ feature supported in IR-based backends only
+//  ^ unsupported in old JVM BE
 
 fun interface KSupplier<T> {
     fun get(): T

compiler/testData/codegen/box/callableReference/funInterfaceConstructor/funInterfaceConstructorEquality.kt

@@ -0,0 +1,41 @@
+// !LANGUAGE: +AllowKotlinFunInterfaceConstructorReference
+
+// DONT_TARGET_EXACT_BACKEND: JVM
+//  ^ old JVM BE generates bogus code that fails in 'invoke', but works almost as expected in terms of equality
+
+// IGNORE_BACKEND: WASM
+//  ^ Failed: ks1 != ks2 (same file, same SAM type)
+
+// IGNORE_BACKEND: JS_IR
+//  ^ Failed: ks1 != ks2 (same file, same SAM type)
+
+// FILE: funInterfaceConstructorEquality.kt
+
+val ks1: (() -> String) -> KSupplier<String> =
+    ::KSupplier
+
+val ks2: (() -> String) -> KSupplier<String> =
+    ::KSupplier
+
+val kn1: (() -> Number) -> KSupplier<Number> =
+    ::KSupplier
+
+fun box(): String {
+    if (ks1 != ks2)
+        return "Failed: ks1 != ks2 (same file, same SAM type)"
+    if (ks1 != ks3)
+        return "Failed: ks1 != ks3 (different file, same SAM type)"
+    if (ks1 != kn1)
+        return "Failed: ks1 != kn1 (same file, same SAM interface, different type arguments)"
+
+    return "OK"
+}
+
+// FILE: KSupplier.kt
+
+fun interface KSupplier<T> {
+    fun get(): T
+}
+
+val ks3: (() -> String) -> KSupplier<String> =
+    ::KSupplier