FIR Checker: check tailrec

Difference from FE1.0
* KT-4285: calls to virtual method with default argument should be
  reported as not tailrec. FE1.0 is missing such cases.
* KT-48600: calls inside lambda should be reported as not tailrec. FE1.0
  also misses such cases.

compiler/testData/codegen/box/diagnostics/functions/tailRecursion/functionWithNoTails.kt

@@ -5,7 +5,6 @@
 // TODO: muted automatically, investigate should it be ran for JS or not
 // DONT_RUN_GENERATED_CODE: JS
 // IGNORE_BACKEND: JS
-// IGNORE_FIR_DIAGNOSTICS_DIFF
 
 <!NO_TAIL_CALLS_FOUND!>tailrec fun noTails()<!> {
     // nothing here

compiler/testData/codegen/box/diagnostics/functions/tailRecursion/labeledThisReferences.kt

@@ -7,7 +7,6 @@
 // TODO: muted automatically, investigate should it be ran for JS or not
 // DONT_RUN_GENERATED_CODE: JS
 // IGNORE_BACKEND: JS
-// IGNORE_FIR_DIAGNOSTICS_DIFF
 
 class B {
     inner class C {

compiler/testData/codegen/box/diagnostics/functions/tailRecursion/loops.kt

@@ -5,7 +5,6 @@
 // TODO: muted automatically, investigate should it be ran for JS or not
 // DONT_RUN_GENERATED_CODE: JS
 // IGNORE_BACKEND: JS
-// IGNORE_FIR_DIAGNOSTICS_DIFF
 
 tailrec fun test(x : Int) : Int {
     var z = if (x > 3) 3 else x

compiler/testData/codegen/box/diagnostics/functions/tailRecursion/multilevelBlocks.kt

@@ -5,7 +5,6 @@
 // TODO: muted automatically, investigate should it be ran for JS or not
 // DONT_RUN_GENERATED_CODE: JS
 // IGNORE_BACKEND: JS
-// IGNORE_FIR_DIAGNOSTICS_DIFF
 
 tailrec fun test(x : Int) : Int {
     if (x == 1) {

compiler/testData/codegen/box/diagnostics/functions/tailRecursion/recursiveCallInInlineLambda.kt

@@ -1,5 +1,6 @@
 // KT-16549
 // IGNORE_BACKEND: JVM
+// IGNORE_FIR_DIAGNOSTICS_DIFF
 
 class TailInline {
     private inline fun act(action: () -> Unit) {

compiler/testData/codegen/box/diagnostics/functions/tailRecursion/recursiveCallInInlineLambdaWithCapture.kt

@@ -1,6 +1,7 @@
 // KT-14961
 // IGNORE_BACKEND: JVM, JS_IR, WASM
 // WITH_RUNTIME
+// IGNORE_FIR_DIAGNOSTICS_DIFF
 
 fun listOfFactor(number: Int): List<Int> {
     tailrec fun listOfFactor(number: Int, acc: List<Int>): List<Int> {

compiler/testData/codegen/box/diagnostics/functions/tailRecursion/recursiveCallInLambda.kt

@@ -7,7 +7,6 @@
 // TODO: muted automatically, investigate should it be ran for JS or not
 // DONT_RUN_GENERATED_CODE: JS
 // IGNORE_BACKEND: JS
-// IGNORE_FIR_DIAGNOSTICS_DIFF
 
 <!NO_TAIL_CALLS_FOUND!>tailrec fun foo()<!> {
     bar {

compiler/testData/codegen/box/diagnostics/functions/tailRecursion/recursiveCallInLocalFunction.kt

@@ -5,7 +5,6 @@
 // TODO: muted automatically, investigate should it be ran for JS or not
 // DONT_RUN_GENERATED_CODE: JS
 // IGNORE_BACKEND: JS
-// IGNORE_FIR_DIAGNOSTICS_DIFF
 
 <!NO_TAIL_CALLS_FOUND!>tailrec fun foo()<!> {
     fun bar() {

compiler/testData/codegen/box/diagnostics/functions/tailRecursion/returnIf.kt

@@ -5,7 +5,6 @@
 // TODO: muted automatically, investigate should it be ran for JS or not
 // DONT_RUN_GENERATED_CODE: JS
 // IGNORE_BACKEND: JS
-// IGNORE_FIR_DIAGNOSTICS_DIFF
 
 tailrec fun test(x : Int) : Int {
     return if (x == 1) {

compiler/testData/codegen/box/diagnostics/functions/tailRecursion/returnInCatch.kt

@@ -5,7 +5,6 @@
 // TODO: muted automatically, investigate should it be ran for JS or not
 // DONT_RUN_GENERATED_CODE: JS
 // IGNORE_BACKEND: JS
-// IGNORE_FIR_DIAGNOSTICS_DIFF
 
 <!NO_TAIL_CALLS_FOUND!>tailrec fun test(counter : Int) : Int<!> {
     if (counter == 0) return 0

compiler/testData/codegen/box/diagnostics/functions/tailRecursion/returnInFinally.kt

@@ -5,7 +5,6 @@
 // TODO: muted automatically, investigate should it be ran for JS or not
 // DONT_RUN_GENERATED_CODE: JS
 // IGNORE_BACKEND: JS
-// IGNORE_FIR_DIAGNOSTICS_DIFF
 
 <!NO_TAIL_CALLS_FOUND!>tailrec fun test(counter : Int) : Int<!> {
     if (counter == 0) return 0

compiler/testData/codegen/box/diagnostics/functions/tailRecursion/returnInIfInFinally.kt

@@ -5,7 +5,6 @@
 // TODO: muted automatically, investigate should it be ran for JS or not
 // DONT_RUN_GENERATED_CODE: JS
 // IGNORE_BACKEND: JS
-// IGNORE_FIR_DIAGNOSTICS_DIFF
 
 <!NO_TAIL_CALLS_FOUND!>tailrec fun test(counter : Int) : Int<!> {
     if (counter == 0) return 0

compiler/testData/codegen/box/diagnostics/functions/tailRecursion/returnInTry.kt

@@ -5,7 +5,6 @@
 // TODO: muted automatically, investigate should it be ran for JS or not
 // DONT_RUN_GENERATED_CODE: JS
 // IGNORE_BACKEND: JS
-// IGNORE_FIR_DIAGNOSTICS_DIFF
 
 <!NO_TAIL_CALLS_FOUND!>tailrec fun test(counter : Int) : Int<!> {
     if (counter == 0) return 0

compiler/testData/codegen/box/diagnostics/functions/tailRecursion/simpleBlock.kt

@@ -5,7 +5,6 @@
 // TODO: muted automatically, investigate should it be ran for JS or not
 // DONT_RUN_GENERATED_CODE: JS
 // IGNORE_BACKEND: JS
-// IGNORE_FIR_DIAGNOSTICS_DIFF
 
 tailrec fun test(x : Int) : Int =
     if (x == 1) {

compiler/testData/codegen/box/diagnostics/functions/tailRecursion/simpleReturn.kt

@@ -5,7 +5,6 @@
 // TODO: muted automatically, investigate should it be ran for JS or not
 // DONT_RUN_GENERATED_CODE: JS
 // IGNORE_BACKEND: JS
-// IGNORE_FIR_DIAGNOSTICS_DIFF
 
 tailrec fun test(x : Int) : Int {
     if (x == 10) {

compiler/testData/codegen/box/diagnostics/functions/tailRecursion/simpleReturnWithElse.kt

@@ -5,7 +5,6 @@
 // TODO: muted automatically, investigate should it be ran for JS or not
 // DONT_RUN_GENERATED_CODE: JS
 // IGNORE_BACKEND: JS
-// IGNORE_FIR_DIAGNOSTICS_DIFF
 
 tailrec fun test(x : Int) : Int {
     if (x == 0) {

compiler/testData/codegen/box/diagnostics/functions/tailRecursion/tailRecursionInFinally.kt

@@ -5,7 +5,6 @@
 // TODO: muted automatically, investigate should it be ran for JS or not
 // DONT_RUN_GENERATED_CODE: JS
 // IGNORE_BACKEND: JS
-// IGNORE_FIR_DIAGNOSTICS_DIFF
 
 <!NO_TAIL_CALLS_FOUND!>tailrec fun test(go: Boolean) : Unit<!> {
     if (!go) return

compiler/testData/codegen/box/diagnostics/functions/tailRecursion/thisReferences.kt

@@ -5,7 +5,6 @@
 // TODO: muted automatically, investigate should it be ran for JS or not
 // DONT_RUN_GENERATED_CODE: JS
 // IGNORE_BACKEND: JS
-// IGNORE_FIR_DIAGNOSTICS_DIFF
 
 class A {
     tailrec fun f1(c : Int) {

compiler/testData/codegen/box/diagnostics/functions/tailRecursion/unitBlocks.kt

@@ -5,7 +5,6 @@
 // TODO: muted automatically, investigate should it be ran for JS or not
 // DONT_RUN_GENERATED_CODE: JS
 // IGNORE_BACKEND: JS
-// IGNORE_FIR_DIAGNOSTICS_DIFF
 
 tailrec fun test(x : Int) : Unit {
     if (x == 1) {

compiler/testData/codegen/box/diagnostics/functions/tailRecursion/whenWithCondition.kt

@@ -5,7 +5,6 @@
 // TODO: muted automatically, investigate should it be ran for JS or not
 // DONT_RUN_GENERATED_CODE: JS
 // IGNORE_BACKEND: JS
-// IGNORE_FIR_DIAGNOSTICS_DIFF
 
 tailrec fun withWhen(counter : Int) : Int =
         when (counter) {

compiler/testData/codegen/box/diagnostics/functions/tailRecursion/whenWithInRange.kt

@@ -7,7 +7,6 @@
 // TODO: muted automatically, investigate should it be ran for JS or not
 // DONT_RUN_GENERATED_CODE: JS
 // IGNORE_BACKEND: JS
-// IGNORE_FIR_DIAGNOSTICS_DIFF
 
 tailrec fun withWhen(counter : Int, d : Any) : Int =
         when (counter) {

compiler/testData/codegen/box/diagnostics/functions/tailRecursion/whenWithoutCondition.kt

@@ -5,7 +5,6 @@
 // TODO: muted automatically, investigate should it be ran for JS or not
 // DONT_RUN_GENERATED_CODE: JS
 // IGNORE_BACKEND: JS
-// IGNORE_FIR_DIAGNOSTICS_DIFF
 
 tailrec fun withWhen2(counter : Int) : Int =
         when {

compiler/testData/diagnostics/tests/tailRecBasic.kt

@@ -0,0 +1,80 @@
+// FIR_IDENTICAL
+// WITH_STDLIB
+// !DIAGNOSTICS: -UNREACHABLE_CODE
+
+<!NO_TAIL_CALLS_FOUND!>tailrec fun foo1()<!> {
+    <!NON_TAIL_RECURSIVE_CALL!>foo1<!>()
+    1
+}
+
+<!NO_TAIL_CALLS_FOUND!>tailrec fun foo2()<!> {
+    <!NON_TAIL_RECURSIVE_CALL!>foo2<!>()
+    val i = 1
+}
+
+<!NO_TAIL_CALLS_FOUND!>tailrec fun foo3()<!> {
+    <!NON_TAIL_RECURSIVE_CALL!>foo3<!>()
+    foo1()
+}
+
+tailrec fun foo4() {
+    if (true) foo4()
+    else foo3()
+}
+
+tailrec fun foo5() {
+    return foo5()
+    foo4()
+}
+
+<!NO_TAIL_CALLS_FOUND!>tailrec fun foo6(b: Boolean)<!> {
+    while (b) {
+        <!NON_TAIL_RECURSIVE_CALL!>foo6<!>(!b)
+    }
+}
+
+tailrec fun foo7_return() {
+    while (true) {
+        foo7_return()
+        return
+    }
+}
+
+<!NO_TAIL_CALLS_FOUND!>tailrec fun foo7_break()<!> {
+    while (true) {
+        <!NON_TAIL_RECURSIVE_CALL!>foo7_break<!>()
+        break
+    }
+}
+
+<!NO_TAIL_CALLS_FOUND!>tailrec fun foo7_continue()<!> {
+    while (true) {
+        <!NON_TAIL_RECURSIVE_CALL!>foo7_continue<!>()
+        continue
+    }
+}
+
+<!NO_TAIL_CALLS_FOUND!>tailrec fun foo8()<!> {
+    while (true) {
+        <!NON_TAIL_RECURSIVE_CALL!>foo8<!>()
+        throw Exception()
+    }
+    foo8()
+}
+
+<!NO_TAIL_CALLS_FOUND!>tailrec fun foo9()<!> {
+    <!NON_TAIL_RECURSIVE_CALL!>foo9<!>()
+    fun bar() {}
+}
+
+<!NO_TAIL_CALLS_FOUND!>tailrec fun foo10()<!> {
+    <!NON_TAIL_RECURSIVE_CALL!>foo10<!>()
+    class Bar {
+        val i = 1
+    }
+}
+
+<!NO_TAIL_CALLS_FOUND!>tailrec fun foo11(): String<!> {
+    return "hello ${<!NON_TAIL_RECURSIVE_CALL!>foo11<!>()}"
+}
+

compiler/testData/diagnostics/tests/tailRecBasic.txt

@@ -0,0 +1,16 @@
+package
+
+public tailrec fun foo1(): kotlin.Unit
+public tailrec fun foo10(): kotlin.Unit
+public tailrec fun foo11(): kotlin.String
+public tailrec fun foo2(): kotlin.Unit
+public tailrec fun foo3(): kotlin.Unit
+public tailrec fun foo4(): kotlin.Unit
+public tailrec fun foo5(): kotlin.Unit
+public tailrec fun foo6(/*0*/ b: kotlin.Boolean): kotlin.Unit
+public tailrec fun foo7_break(): kotlin.Unit
+public tailrec fun foo7_continue(): kotlin.Unit
+public tailrec fun foo7_return(): kotlin.Unit
+public tailrec fun foo8(): kotlin.Unit
+public tailrec fun foo9(): kotlin.Unit
+

compiler/testData/diagnostics/tests/tailRecInNestedScopes.fir.kt

@@ -0,0 +1,37 @@
+// WITH_STDLIB
+
+<!NO_TAIL_CALLS_FOUND!>tailrec fun foo1()<!> {
+    run {
+        <!NON_TAIL_RECURSIVE_CALL!>foo1<!>()
+    }
+}
+
+fun myRun(f: () -> Unit) = f()
+
+
+<!NO_TAIL_CALLS_FOUND!>tailrec fun foo2()<!> {
+    myRun {
+        <!NON_TAIL_RECURSIVE_CALL!>foo2<!>()
+    }
+}
+
+<!NO_TAIL_CALLS_FOUND!>tailrec fun foo3()<!> {
+    fun bar() {
+        <!NON_TAIL_RECURSIVE_CALL!>foo3<!>()
+    }
+    bar()
+}
+
+class A {
+    <!NO_TAIL_CALLS_FOUND!>tailrec fun foo4()<!> {
+        with(this) {
+            <!NON_TAIL_RECURSIVE_CALL!>foo4<!>()
+        }
+    }
+}
+
+<!NO_TAIL_CALLS_FOUND!>tailrec fun foo5()<!> {
+    run {
+        return <!NON_TAIL_RECURSIVE_CALL!>foo5<!>()
+    }
+}

compiler/testData/diagnostics/tests/tailRecInNestedScopes.kt

@@ -0,0 +1,37 @@
+// WITH_STDLIB
+
+<!NO_TAIL_CALLS_FOUND!>tailrec fun foo1()<!> {
+    run {
+        <!NON_TAIL_RECURSIVE_CALL!>foo1<!>()
+    }
+}
+
+fun myRun(f: () -> Unit) = f()
+
+
+<!NO_TAIL_CALLS_FOUND!>tailrec fun foo2()<!> {
+    myRun {
+        <!NON_TAIL_RECURSIVE_CALL!>foo2<!>()
+    }
+}
+
+<!NO_TAIL_CALLS_FOUND!>tailrec fun foo3()<!> {
+    fun bar() {
+        <!NON_TAIL_RECURSIVE_CALL!>foo3<!>()
+    }
+    bar()
+}
+
+class A {
+    <!NO_TAIL_CALLS_FOUND!>tailrec fun foo4()<!> {
+        with(this) {
+            <!NON_TAIL_RECURSIVE_CALL!>foo4<!>()
+        }
+    }
+}
+
+tailrec fun foo5() {
+    run {
+        return foo5()
+    }
+}

compiler/testData/diagnostics/tests/tailRecInNestedScopes.txt

@@ -0,0 +1,16 @@
+package
+
+public tailrec fun foo1(): kotlin.Unit
+public tailrec fun foo2(): kotlin.Unit
+public tailrec fun foo3(): kotlin.Unit
+public tailrec fun foo5(): kotlin.Unit
+public fun myRun(/*0*/ f: () -> kotlin.Unit): kotlin.Unit
+
+public final class A {
+    public constructor A()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public final tailrec fun foo4(): 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/tailRecInTry.kt

@@ -0,0 +1,64 @@
+// FIR_IDENTICAL
+<!NO_TAIL_CALLS_FOUND!>tailrec fun foo1()<!> {
+    try {
+        <!TAIL_RECURSION_IN_TRY_IS_NOT_SUPPORTED!>foo1<!>()
+    } catch (e: Exception) {
+        <!TAIL_RECURSION_IN_TRY_IS_NOT_SUPPORTED!>foo1<!>()
+    } finally {
+        <!TAIL_RECURSION_IN_TRY_IS_NOT_SUPPORTED!>foo1<!>()
+    }
+}
+
+<!NO_TAIL_CALLS_FOUND!>tailrec fun foo2()<!> {
+    try {
+        <!TAIL_RECURSION_IN_TRY_IS_NOT_SUPPORTED!>foo2<!>()
+        foo1()
+    } catch (e: Exception) {
+        <!TAIL_RECURSION_IN_TRY_IS_NOT_SUPPORTED!>foo2<!>()
+        foo1()
+    } finally {
+        <!TAIL_RECURSION_IN_TRY_IS_NOT_SUPPORTED!>foo2<!>()
+        foo1()
+    }
+}
+
+<!NO_TAIL_CALLS_FOUND!>tailrec fun foo3()<!> {
+    try {
+        try {
+            <!TAIL_RECURSION_IN_TRY_IS_NOT_SUPPORTED!>foo3<!>()
+        } finally {
+        }
+    } catch (e: Exception) {
+        try {
+            <!TAIL_RECURSION_IN_TRY_IS_NOT_SUPPORTED!>foo3<!>()
+        } finally {
+        }
+    } finally {
+        try {
+            <!TAIL_RECURSION_IN_TRY_IS_NOT_SUPPORTED!>foo3<!>()
+        } finally {
+        }
+    }
+}
+
+<!NO_TAIL_CALLS_FOUND!>tailrec fun foo4()<!> {
+    try {
+        if (true) {
+            <!TAIL_RECURSION_IN_TRY_IS_NOT_SUPPORTED!>foo4<!>()
+        } else {
+            foo1()
+        }
+    } catch (e: Exception) {
+        if (true) {
+            <!TAIL_RECURSION_IN_TRY_IS_NOT_SUPPORTED!>foo4<!>()
+        } else {
+            foo1()
+        }
+    } finally {
+        if (true) {
+            <!TAIL_RECURSION_IN_TRY_IS_NOT_SUPPORTED!>foo4<!>()
+        } else {
+            foo1()
+        }
+    }
+}

compiler/testData/diagnostics/tests/tailRecInTry.txt

@@ -0,0 +1,7 @@
+package
+
+public tailrec fun foo1(): kotlin.Unit
+public tailrec fun foo2(): kotlin.Unit
+public tailrec fun foo3(): kotlin.Unit
+public tailrec fun foo4(): kotlin.Unit
+

compiler/testData/diagnostics/tests/tailRecOnVirtualMember.fir.kt

@@ -1,15 +1,15 @@
 //!LANGUAGE: -ProhibitTailrecOnVirtualMember
 
 open class A {
-    tailrec open fun foo(x: Int) {
+    <!TAILREC_ON_VIRTUAL_MEMBER_ERROR!>tailrec open fun foo(x: Int)<!> {
         foo(x)
     }
 
-    internal tailrec open fun bar(y: Int) {
+    <!TAILREC_ON_VIRTUAL_MEMBER_ERROR!>internal tailrec open fun bar(y: Int)<!> {
         bar(y)
     }
 
-    protected tailrec open fun baz(y: Int) {
+    <!TAILREC_ON_VIRTUAL_MEMBER_ERROR!>protected tailrec open fun baz(y: Int)<!> {
         baz(y)
     }
 
@@ -38,15 +38,15 @@ open class B : A() {
 
 
 open class C : A() {
-    tailrec override fun foo(x: Int) {
+    <!TAILREC_ON_VIRTUAL_MEMBER_ERROR!>tailrec override fun foo(x: Int)<!> {
         foo(x)
     }
 
-    tailrec override fun bar(y: Int) {
+    <!TAILREC_ON_VIRTUAL_MEMBER_ERROR!>tailrec override fun bar(y: Int)<!> {
         bar(y)
     }
 
-    tailrec override fun baz(y: Int) {
+    <!TAILREC_ON_VIRTUAL_MEMBER_ERROR!>tailrec override fun baz(y: Int)<!> {
         baz(y)
     }
 }
@@ -66,15 +66,15 @@ object D : A() {
 }
 
 sealed class E : A() {
-    tailrec override fun foo(x: Int) {
+    <!TAILREC_ON_VIRTUAL_MEMBER_ERROR!>tailrec override fun foo(x: Int)<!> {
         foo(x)
     }
 
-    tailrec override fun bar(y: Int) {
+    <!TAILREC_ON_VIRTUAL_MEMBER_ERROR!>tailrec override fun bar(y: Int)<!> {
         bar(y)
     }
 
-    tailrec override fun baz(y: Int) {
+    <!TAILREC_ON_VIRTUAL_MEMBER_ERROR!>tailrec override fun baz(y: Int)<!> {
         baz(y)
     }
 
@@ -109,15 +109,15 @@ enum class F {
         }
     };
 
-    tailrec open fun foo(x: Int) {
+    <!TAILREC_ON_VIRTUAL_MEMBER_ERROR!>tailrec open fun foo(x: Int)<!> {
         foo(x)
     }
 
-    internal tailrec open fun bar(y: Int) {
+    <!TAILREC_ON_VIRTUAL_MEMBER_ERROR!>internal tailrec open fun bar(y: Int)<!> {
         bar(y)
     }
 
-    protected tailrec open fun baz(y: Int) {
+    <!TAILREC_ON_VIRTUAL_MEMBER_ERROR!>protected tailrec open fun baz(y: Int)<!> {
         baz(y)
     }
 
@@ -134,15 +134,15 @@ enum class G {
 
     G1;
 
-    tailrec open fun foo(x: Int) {
+    <!TAILREC_ON_VIRTUAL_MEMBER_ERROR!>tailrec open fun foo(x: Int)<!> {
         foo(x)
     }
 
-    internal tailrec open fun bar(y: Int) {
+    <!TAILREC_ON_VIRTUAL_MEMBER_ERROR!>internal tailrec open fun bar(y: Int)<!> {
         bar(y)
     }
 
-    protected tailrec open fun baz(y: Int) {
+    <!TAILREC_ON_VIRTUAL_MEMBER_ERROR!>protected tailrec open fun baz(y: Int)<!> {
         baz(y)
     }
 

compiler/testData/diagnostics/tests/tailRecOnVirtualMemberError.fir.kt

@@ -1,170 +0,0 @@
-//!LANGUAGE: +ProhibitTailrecOnVirtualMember
-
-open class A {
-    tailrec open fun foo(x: Int) {
-        foo(x)
-    }
-
-    internal tailrec open fun bar(y: Int) {
-        bar(y)
-    }
-
-    protected tailrec open fun baz(y: Int) {
-        baz(y)
-    }
-
-    private tailrec fun boo(y: Int) {
-        boo(y)
-    }
-
-    internal tailrec fun baa(y: Int) {
-        baa(y)
-    }
-}
-
-open class B : A() {
-    final tailrec override fun foo(x: Int) {
-        foo(x)
-    }
-
-    final tailrec override fun bar(y: Int) {
-        bar(y)
-    }
-
-    final tailrec override fun baz(y: Int) {
-        baz(y)
-    }
-}
-
-
-open class C : A() {
-    tailrec override fun foo(x: Int) {
-        foo(x)
-    }
-
-    tailrec override fun bar(y: Int) {
-        bar(y)
-    }
-
-    tailrec override fun baz(y: Int) {
-        baz(y)
-    }
-}
-
-object D : A() {
-    tailrec override fun foo(x: Int) {
-        foo(x)
-    }
-
-    tailrec override fun bar(y: Int) {
-        bar(y - 1)
-    }
-
-    tailrec override fun baz(y: Int) {
-        baz(y)
-    }
-}
-
-sealed class E : A() {
-    tailrec override fun foo(x: Int) {
-        foo(x)
-    }
-
-    tailrec override fun bar(y: Int) {
-        bar(y)
-    }
-
-    tailrec override fun baz(y: Int) {
-        baz(y)
-    }
-
-    class E1 : E() {
-        tailrec override fun foo(x: Int) {
-            foo(x)
-        }
-
-        tailrec override fun bar(y: Int) {
-            bar(y)
-        }
-
-        tailrec override fun baz(y: Int) {
-            baz(y)
-        }
-    }
-}
-
-enum class F {
-    F0,
-    F1() {
-        tailrec override fun foo(x: Int) {
-            foo(x)
-        }
-
-        tailrec override fun bar(y: Int) {
-            bar(y)
-        }
-
-        tailrec override fun baz(y: Int) {
-            baz(y)
-        }
-    };
-
-    tailrec open fun foo(x: Int) {
-        foo(x)
-    }
-
-    internal tailrec open fun bar(y: Int) {
-        bar(y)
-    }
-
-    protected tailrec open fun baz(y: Int) {
-        baz(y)
-    }
-
-    private tailrec fun boo(y: Int) {
-        boo(y)
-    }
-
-    internal tailrec fun baa(y: Int) {
-        baa(y)
-    }
-}
-
-enum class G {
-
-    G1;
-
-    tailrec open fun foo(x: Int) {
-        foo(x)
-    }
-
-    internal tailrec open fun bar(y: Int) {
-        bar(y)
-    }
-
-    protected tailrec open fun baz(y: Int) {
-        baz(y)
-    }
-
-    private tailrec fun boo(y: Int) {
-        boo(y)
-    }
-
-    internal tailrec fun baa(y: Int) {
-        baa(y)
-    }
-}
-
-val z = object : A() {
-    tailrec override fun foo(x: Int) {
-        foo(x)
-    }
-
-    tailrec override fun bar(y: Int) {
-        bar(y)
-    }
-
-    tailrec override fun baz(y: Int) {
-        baz(y)
-    }
-}

compiler/testData/diagnostics/tests/tailRecOnVirtualMemberError.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 //!LANGUAGE: +ProhibitTailrecOnVirtualMember
 
 open class A {

compiler/testData/diagnostics/tests/tailRecOverridden.fir.kt

@@ -6,12 +6,12 @@ open class A {
 }
 
 class B: A() {
-    tailrec override fun foo(x: Int) {
-        foo()
+    <!NO_TAIL_CALLS_FOUND!>tailrec override fun foo(x: Int)<!> {
+        <!NON_TAIL_RECURSIVE_CALL!>foo<!>()
     }
 
-    tailrec override fun gav(y: Int, z: Int) {
-        gav(y)
+    <!NO_TAIL_CALLS_FOUND!>tailrec override fun gav(y: Int, z: Int)<!> {
+        <!NON_TAIL_RECURSIVE_CALL!>gav<!>(y)
     }
 
     tailrec fun bar(y: Double): Double = bar(y * 2.0)
@@ -29,4 +29,4 @@ class C: A() {
     tailrec fun bar(y: Int = 1, z: Int = 2) {
         bar(z)
     }
-}
+}

compiler/testData/diagnostics/tests/tailRecSingleton.fir.kt

@@ -0,0 +1,53 @@
+object Foo {
+    tailrec fun foo1() {
+        foo1()
+    }
+
+    tailrec fun foo2() {
+        this.foo2()
+    }
+
+    <!NO_TAIL_CALLS_FOUND!>tailrec fun foo3()<!> {
+        Foo.<!NON_TAIL_RECURSIVE_CALL!>foo3<!>()
+    }
+}
+
+class Bar {
+    companion object {
+        tailrec fun bar1() {
+            bar1()
+        }
+
+        tailrec fun bar2() {
+            this.bar2()
+        }
+
+        <!NO_TAIL_CALLS_FOUND!>tailrec fun bar3()<!> {
+            Bar.<!NON_TAIL_RECURSIVE_CALL!>bar3<!>()
+        }
+
+        <!NO_TAIL_CALLS_FOUND!>tailrec fun bar4()<!> {
+            Bar.Companion.<!NON_TAIL_RECURSIVE_CALL!>bar4<!>()
+        }
+    }
+}
+
+enum class E {
+    A {
+        override tailrec fun rec() {
+            rec()
+        }
+    },
+    B {
+        override tailrec fun rec() {
+            this.rec()
+        }
+    },
+    C {
+        <!NO_TAIL_CALLS_FOUND!>override tailrec fun rec()<!> {
+            C.rec() // resolution goes to `E.rec`. Hence the resolved symbol is considered different from `C.rec`.
+        }
+    };
+
+    abstract fun rec()
+}

compiler/testData/diagnostics/tests/tailRecSingleton.kt

@@ -0,0 +1,53 @@
+object Foo {
+    tailrec fun foo1() {
+        foo1()
+    }
+
+    tailrec fun foo2() {
+        this.foo2()
+    }
+
+    tailrec fun foo3() {
+        Foo.foo3()
+    }
+}
+
+class Bar {
+    companion object {
+        tailrec fun bar1() {
+            bar1()
+        }
+
+        tailrec fun bar2() {
+            this.bar2()
+        }
+
+        <!NO_TAIL_CALLS_FOUND!>tailrec fun bar3()<!> {
+            Bar.<!NON_TAIL_RECURSIVE_CALL!>bar3<!>()
+        }
+
+        tailrec fun bar4() {
+            Bar.Companion.bar4()
+        }
+    }
+}
+
+enum class E {
+    A {
+        override tailrec fun rec() {
+            rec()
+        }
+    },
+    B {
+        override tailrec fun rec() {
+            this.rec()
+        }
+    },
+    C {
+        <!NO_TAIL_CALLS_FOUND!>override tailrec fun rec()<!> {
+            C.rec() // resolution goes to `E.rec`. Hence the resolved symbol is considered different from `C.rec`.
+        }
+    };
+
+    abstract fun rec()
+}

compiler/testData/diagnostics/tests/tailRecSingleton.txt

@@ -0,0 +1,54 @@
+package
+
+public final class Bar {
+    public constructor Bar()
+    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 companion object Companion {
+        private constructor Companion()
+        public final tailrec fun bar1(): kotlin.Unit
+        public final tailrec fun bar2(): kotlin.Unit
+        public final tailrec fun bar3(): kotlin.Unit
+        public final tailrec fun bar4(): kotlin.Unit
+        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 enum class E : kotlin.Enum<E> {
+    enum entry A
+
+    enum entry B
+
+    enum entry C
+
+    private constructor E()
+    public final override /*1*/ /*fake_override*/ val name: kotlin.String
+    public final override /*1*/ /*fake_override*/ val ordinal: kotlin.Int
+    protected final override /*1*/ /*fake_override*/ fun clone(): kotlin.Any
+    public final override /*1*/ /*fake_override*/ fun compareTo(/*0*/ other: E): kotlin.Int
+    public final override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    protected/*protected and package*/ final override /*1*/ /*fake_override*/ /*isHiddenForResolutionEverywhereBesideSupercalls*/ fun finalize(): kotlin.Unit
+    public final override /*1*/ /*fake_override*/ /*isHiddenForResolutionEverywhereBesideSupercalls*/ fun getDeclaringClass(): java.lang.Class<E!>!
+    public final override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public abstract fun rec(): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+
+    // Static members
+    public final /*synthesized*/ fun valueOf(/*0*/ value: kotlin.String): E
+    public final /*synthesized*/ fun values(): kotlin.Array<E>
+}
+
+public object Foo {
+    private constructor Foo()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public final tailrec fun foo1(): kotlin.Unit
+    public final tailrec fun foo2(): kotlin.Unit
+    public final tailrec fun foo3(): 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/tailRecWithDispatchReceiver.kt

@@ -0,0 +1,21 @@
+// FIR_IDENTICAL
+class A(val a: A) {
+    <!NO_TAIL_CALLS_FOUND!>tailrec fun foo1()<!> {
+        a.<!NON_TAIL_RECURSIVE_CALL!>foo1<!>()
+    }
+
+    tailrec fun foo2() {
+        this.foo2()
+    }
+
+    tailrec fun foo3() {
+        foo3()
+    }
+
+    <!NO_TAIL_CALLS_FOUND!>tailrec fun foo4()<!> {
+        with(a) {
+            <!NON_TAIL_RECURSIVE_CALL!>foo4<!>()
+            return
+        }
+    }
+}

compiler/testData/diagnostics/tests/tailRecWithDispatchReceiver.txt

@@ -0,0 +1,14 @@
+package
+
+public final class A {
+    public constructor A(/*0*/ a: A)
+    public final val a: A
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public final tailrec fun foo1(): kotlin.Unit
+    public final tailrec fun foo2(): kotlin.Unit
+    public final tailrec fun foo3(): kotlin.Unit
+    public final tailrec fun foo4(): 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/tailRecWithExtensionReceiver.kt

@@ -0,0 +1,14 @@
+// FIR_IDENTICAL
+tailrec fun String.foo1() {
+    "".foo1()
+}
+
+tailrec fun String.foo2() {
+    this.foo2()
+}
+
+<!NO_TAIL_CALLS_FOUND!>tailrec fun String.foo3()<!> {
+    with(this) {
+        <!NON_TAIL_RECURSIVE_CALL!>foo3<!>()
+    }
+}

compiler/testData/diagnostics/tests/tailRecWithExtensionReceiver.txt

@@ -0,0 +1,5 @@
+package
+
+public tailrec fun kotlin.String.foo1(): kotlin.Unit
+public tailrec fun kotlin.String.foo2(): kotlin.Unit
+public tailrec fun kotlin.String.foo3(): kotlin.Unit

compiler/testData/diagnostics/tests/tailRecursionComplex.fir.kt

@@ -1,10 +1,10 @@
 object O {
-    // This is correct, foo is the same
-    tailrec fun foo(i: Int): Int = if (i < 0) 0 else O.foo(i - 1)
+    // foo is the same, but the compiler currently doesn't compile this as tail recursive. See KT-48602
+    <!NO_TAIL_CALLS_FOUND!>tailrec fun foo(i: Int): Int<!> = if (i < 0) 0 else O.<!NON_TAIL_RECURSIVE_CALL!>foo<!>(i - 1)
 }
 
 class A {
-    tailrec fun foo(i: Int) = if (i < 0) 0 else A.foo(i - 1)
+    <!NO_TAIL_CALLS_FOUND!>tailrec fun foo(i: Int)<!> = if (i < 0) 0 else A.foo(i - 1)
 
     companion object {
         fun foo(i: Int) = 42 + i
@@ -12,5 +12,5 @@ class A {
 }
 
 class B {
-    tailrec fun foo(i: Int) = if (i < 0) 0 else O.foo(i - 1)
-}
+    <!NO_TAIL_CALLS_FOUND!>tailrec fun foo(i: Int)<!> = if (i < 0) 0 else O.foo(i - 1)
+}

compiler/testData/diagnostics/tests/tailRecursionComplex.kt

@@ -1,5 +1,5 @@
 object O {
-    // This is correct, foo is the same
+    // foo is the same, but the compiler currently doesn't compile this as tail recursive. See KT-48602
     tailrec fun foo(i: Int): Int = if (i < 0) 0 else O.foo(i - 1)
 }