diff --git a/idea/testData/checker/Casts.kt b/idea/testData/checker/Casts.kt
index 75aadf93089..b5ad02fc9c9 100644
--- a/idea/testData/checker/Casts.kt
+++ b/idea/testData/checker/Casts.kt
@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 fun <T> checkSubtype(t: T) = t
 
 fun test() : Unit {
diff --git a/idea/testData/checker/FunctionOnlyOneTypeParametersList.kt b/idea/testData/checker/FunctionOnlyOneTypeParametersList.kt
index 82237028c54..87391bc18b0 100644
--- a/idea/testData/checker/FunctionOnlyOneTypeParametersList.kt
+++ b/idea/testData/checker/FunctionOnlyOneTypeParametersList.kt
@@ -1 +1,3 @@
+// FIR_COMPARISON
+
 fun <T> foo<error><SOME_TYPE></error> () {}
\ No newline at end of file
diff --git a/idea/testData/checker/MainWithWarningOnUnusedParam.kt b/idea/testData/checker/MainWithWarningOnUnusedParam.kt
index f503a2e9140..07f402a7eba 100644
--- a/idea/testData/checker/MainWithWarningOnUnusedParam.kt
+++ b/idea/testData/checker/MainWithWarningOnUnusedParam.kt
@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 // LANGUAGE_VERSION: 1.4
 
 fun main(<warning descr="[UNUSED_PARAMETER] Parameter 'args' is never used">args</warning>: Array<String>) {
diff --git a/idea/testData/checker/MainWithoutWarningOnUnusedParam.kt b/idea/testData/checker/MainWithoutWarningOnUnusedParam.kt
index d2da7cd6cda..7fb0c29fbfe 100644
--- a/idea/testData/checker/MainWithoutWarningOnUnusedParam.kt
+++ b/idea/testData/checker/MainWithoutWarningOnUnusedParam.kt
@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 // LANGUAGE_VERSION: 1.3
 
 fun main(args: Array<String>) {
diff --git a/idea/testData/checker/MultipleModality.kt b/idea/testData/checker/MultipleModality.kt
index 8094a2f109b..405a3c4ea73 100644
--- a/idea/testData/checker/MultipleModality.kt
+++ b/idea/testData/checker/MultipleModality.kt
@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 sealed <warning descr="[REDUNDANT_MODIFIER] Modifier 'abstract' is redundant because 'sealed' is present">abstract</warning> class First
 
 <warning descr="[REDUNDANT_MODIFIER] Modifier 'abstract' is redundant because 'sealed' is present">abstract</warning> sealed class Second
diff --git a/idea/testData/checker/PackageQualified.kt b/idea/testData/checker/PackageQualified.kt
index 45e1dcc1524..0fcc05274f1 100644
--- a/idea/testData/checker/PackageQualified.kt
+++ b/idea/testData/checker/PackageQualified.kt
@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 package a
 
     import java.*
diff --git a/idea/testData/checker/Unused.kt b/idea/testData/checker/Unused.kt
index 33b3ad70ba3..6c21bfa594c 100644
--- a/idea/testData/checker/Unused.kt
+++ b/idea/testData/checker/Unused.kt
@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 fun test(<warning textAttributesKey="NOT_USED_ELEMENT_ATTRIBUTES">unusedParam</warning>: Int) { // UNUSED_PARAMETER
   val str = ":)"
   str <warning textAttributesKey="NOT_USED_ELEMENT_ATTRIBUTES">as String</warning> // USELESS_CAST
diff --git a/idea/testData/checker/WhenInEnumInExtensionProperty.kt b/idea/testData/checker/WhenInEnumInExtensionProperty.kt
index 03f847df429..5db12fdee0a 100644
--- a/idea/testData/checker/WhenInEnumInExtensionProperty.kt
+++ b/idea/testData/checker/WhenInEnumInExtensionProperty.kt
@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 // KT-3750 When without else
 
 enum class A {
diff --git a/idea/testData/checker/duplicateJvmSignature/functionAndProperty/ambiguous.kt b/idea/testData/checker/duplicateJvmSignature/functionAndProperty/ambiguous.kt
index 0ac42f41f7f..268c222e589 100644
--- a/idea/testData/checker/duplicateJvmSignature/functionAndProperty/ambiguous.kt
+++ b/idea/testData/checker/duplicateJvmSignature/functionAndProperty/ambiguous.kt
@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 package a.b
 
 class String
diff --git a/idea/testData/checker/duplicateJvmSignature/functionAndProperty/class.kt b/idea/testData/checker/duplicateJvmSignature/functionAndProperty/class.kt
index 18a43126837..ba9caec2747 100644
--- a/idea/testData/checker/duplicateJvmSignature/functionAndProperty/class.kt
+++ b/idea/testData/checker/duplicateJvmSignature/functionAndProperty/class.kt
@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 class C {
     <error>val x</error> = 1
     <error>fun getX()</error> = 1
diff --git a/idea/testData/checker/duplicateJvmSignature/functionAndProperty/classObject.kt b/idea/testData/checker/duplicateJvmSignature/functionAndProperty/classObject.kt
index 487d6326158..abb65bf3831 100644
--- a/idea/testData/checker/duplicateJvmSignature/functionAndProperty/classObject.kt
+++ b/idea/testData/checker/duplicateJvmSignature/functionAndProperty/classObject.kt
@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 class C {
     companion object {
         <error>val x</error> = 1
diff --git a/idea/testData/checker/duplicateJvmSignature/functionAndProperty/localClass.kt b/idea/testData/checker/duplicateJvmSignature/functionAndProperty/localClass.kt
index 2fb323c47ce..8afb7a999c7 100644
--- a/idea/testData/checker/duplicateJvmSignature/functionAndProperty/localClass.kt
+++ b/idea/testData/checker/duplicateJvmSignature/functionAndProperty/localClass.kt
@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 fun foo() {
     class C {
         <error>val x</error> = 1
diff --git a/idea/testData/checker/duplicateJvmSignature/functionAndProperty/nestedClass.kt b/idea/testData/checker/duplicateJvmSignature/functionAndProperty/nestedClass.kt
index e70ccffb289..b131d130e76 100644
--- a/idea/testData/checker/duplicateJvmSignature/functionAndProperty/nestedClass.kt
+++ b/idea/testData/checker/duplicateJvmSignature/functionAndProperty/nestedClass.kt
@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 class B {
     class C {
         <error>val x</error> = 1
diff --git a/idea/testData/checker/duplicateJvmSignature/functionAndProperty/object.kt b/idea/testData/checker/duplicateJvmSignature/functionAndProperty/object.kt
index 0234305c8d3..8a0f1a752cf 100644
--- a/idea/testData/checker/duplicateJvmSignature/functionAndProperty/object.kt
+++ b/idea/testData/checker/duplicateJvmSignature/functionAndProperty/object.kt
@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 object C {
     <error>val x</error> = 1
     <error>fun getX()</error> = 1
diff --git a/idea/testData/checker/duplicateJvmSignature/functionAndProperty/objectExpression.kt b/idea/testData/checker/duplicateJvmSignature/functionAndProperty/objectExpression.kt
index 5b1d0da0fe5..6da4240e309 100644
--- a/idea/testData/checker/duplicateJvmSignature/functionAndProperty/objectExpression.kt
+++ b/idea/testData/checker/duplicateJvmSignature/functionAndProperty/objectExpression.kt
@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 fun foo() =
     object {
         <error>val x</error> = 1
diff --git a/idea/testData/checker/duplicateJvmSignature/functionAndProperty/topLevel.kt b/idea/testData/checker/duplicateJvmSignature/functionAndProperty/topLevel.kt
index 71efcfa7655..e894cb0d99b 100644
--- a/idea/testData/checker/duplicateJvmSignature/functionAndProperty/topLevel.kt
+++ b/idea/testData/checker/duplicateJvmSignature/functionAndProperty/topLevel.kt
@@ -1,2 +1,4 @@
+// FIR_COMPARISON
+
 <error>val x</error> = 1
 <error>fun getX()</error> = 1
\ No newline at end of file
diff --git a/idea/testData/checker/duplicateJvmSignature/functionAndProperty/topLevelMultifileRuntime.kt b/idea/testData/checker/duplicateJvmSignature/functionAndProperty/topLevelMultifileRuntime.kt
index 80d6b6cf485..3566bf1a7ba 100644
--- a/idea/testData/checker/duplicateJvmSignature/functionAndProperty/topLevelMultifileRuntime.kt
+++ b/idea/testData/checker/duplicateJvmSignature/functionAndProperty/topLevelMultifileRuntime.kt
@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 // RUNTIME
 @file:JvmName("TopLevelMultifile")
 @file:JvmMultifileClass
diff --git a/idea/testData/checker/duplicateJvmSignature/functionAndProperty/trait.kt b/idea/testData/checker/duplicateJvmSignature/functionAndProperty/trait.kt
index 12a99607204..f8793460b8e 100644
--- a/idea/testData/checker/duplicateJvmSignature/functionAndProperty/trait.kt
+++ b/idea/testData/checker/duplicateJvmSignature/functionAndProperty/trait.kt
@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 interface T {
     <error descr="[CONFLICTING_JVM_DECLARATIONS] Platform declaration clash: The following declarations have the same JVM signature (foo(Ljava/util/List;)V):
     fun foo(l: List<Int>): Unit defined in T
diff --git a/idea/testData/checker/infos/SmartCastOnIf.kt b/idea/testData/checker/infos/SmartCastOnIf.kt
index e8dc87a3ece..f24b5ecff3f 100644
--- a/idea/testData/checker/infos/SmartCastOnIf.kt
+++ b/idea/testData/checker/infos/SmartCastOnIf.kt
@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 fun baz(s: String?): Int {
     return if (s == null) {
         ""
diff --git a/idea/testData/checker/infos/SmartCastOnWhen.kt b/idea/testData/checker/infos/SmartCastOnWhen.kt
index 8fc15bcc7fa..d05e7bfe0dc 100644
--- a/idea/testData/checker/infos/SmartCastOnWhen.kt
+++ b/idea/testData/checker/infos/SmartCastOnWhen.kt
@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 // COMPILER_ARGUMENTS: -XXLanguage:-NewInference
 
 fun baz(s: String?): Int {
diff --git a/idea/testData/checker/infos/SmartCastTarget.kt b/idea/testData/checker/infos/SmartCastTarget.kt
index 7fc42156bfd..6850dff6ce3 100644
--- a/idea/testData/checker/infos/SmartCastTarget.kt
+++ b/idea/testData/checker/infos/SmartCastTarget.kt
@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 // See KT-15901
 
 <info>enum</info> class En { A }
diff --git a/idea/testData/checker/infos/SmartCastToEnum.kt b/idea/testData/checker/infos/SmartCastToEnum.kt
index 3542cca816d..e6fef150c5e 100644
--- a/idea/testData/checker/infos/SmartCastToEnum.kt
+++ b/idea/testData/checker/infos/SmartCastToEnum.kt
@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 package test2
 
 <info descr="null">enum</info> class En { A, B, С }
diff --git a/idea/testData/checker/infos/SmartCastsWithSafeAccess.kt b/idea/testData/checker/infos/SmartCastsWithSafeAccess.kt
index e34b3f23323..146cd5f8058 100644
--- a/idea/testData/checker/infos/SmartCastsWithSafeAccess.kt
+++ b/idea/testData/checker/infos/SmartCastsWithSafeAccess.kt
@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 interface A {
     fun foo()
 }
diff --git a/idea/testData/checker/infos/WrapIntoRef.kt b/idea/testData/checker/infos/WrapIntoRef.kt
index 94fcb64eb9a..7783e1cb7e2 100644
--- a/idea/testData/checker/infos/WrapIntoRef.kt
+++ b/idea/testData/checker/infos/WrapIntoRef.kt
@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 fun refs() {
     var <warning>a</warning> = 1
     val <warning>v</warning> = {
diff --git a/idea/testData/checker/infos/multipleResolvedCalls.kt b/idea/testData/checker/infos/multipleResolvedCalls.kt
index 76a6c1e9152..9818e84ef2e 100644
--- a/idea/testData/checker/infos/multipleResolvedCalls.kt
+++ b/idea/testData/checker/infos/multipleResolvedCalls.kt
@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 interface I1
 interface I2
 interface I3
diff --git a/idea/testData/checker/infos/smartCastOnElvis.kt b/idea/testData/checker/infos/smartCastOnElvis.kt
index 32c812f1d32..cade61c18c6 100644
--- a/idea/testData/checker/infos/smartCastOnElvis.kt
+++ b/idea/testData/checker/infos/smartCastOnElvis.kt
@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 // COMPILER_ARGUMENTS: -XXLanguage:-NewInference
 
 fun foo(s: String) = s.length
diff --git a/idea/testData/checker/regression/AssignmentsUnderOperators.kt b/idea/testData/checker/regression/AssignmentsUnderOperators.kt
index a92e8e3d10a..ee8f2f88802 100644
--- a/idea/testData/checker/regression/AssignmentsUnderOperators.kt
+++ b/idea/testData/checker/regression/AssignmentsUnderOperators.kt
@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 fun test() {
   var a : Any? = null
   if (a is Any) else a = null;
diff --git a/idea/testData/checker/regression/BadParseForClass.kt b/idea/testData/checker/regression/BadParseForClass.kt
index 5ea57af0892..0a49f4d4d12 100644
--- a/idea/testData/checker/regression/BadParseForClass.kt
+++ b/idea/testData/checker/regression/BadParseForClass.kt
@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 fun main(args: Array<String>) {
     String.class<EOLError descr="Name expected"></EOLError>
 }
diff --git a/idea/testData/checker/regression/ClassDeclarationAfterDot.kt b/idea/testData/checker/regression/ClassDeclarationAfterDot.kt
index e3d955ecb65..16b94e3c8db 100644
--- a/idea/testData/checker/regression/ClassDeclarationAfterDot.kt
+++ b/idea/testData/checker/regression/ClassDeclarationAfterDot.kt
@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 class A
 
 fun f() {
diff --git a/idea/testData/checker/regression/ClassDeclarationAfterDot2.kt b/idea/testData/checker/regression/ClassDeclarationAfterDot2.kt
index 4b784e6a5f6..eb9fd988186 100644
--- a/idea/testData/checker/regression/ClassDeclarationAfterDot2.kt
+++ b/idea/testData/checker/regression/ClassDeclarationAfterDot2.kt
@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 class A
 
 fun f() {
diff --git a/idea/testData/checker/regression/ClassDeclarationAsExpression.kt b/idea/testData/checker/regression/ClassDeclarationAsExpression.kt
index 7949d9b9a40..929179ee461 100644
--- a/idea/testData/checker/regression/ClassDeclarationAsExpression.kt
+++ b/idea/testData/checker/regression/ClassDeclarationAsExpression.kt
@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 val p = 1 < <error>class A {
     fun f() {
         f()
diff --git a/idea/testData/checker/regression/ClassDeclarationAsExpression2.kt b/idea/testData/checker/regression/ClassDeclarationAsExpression2.kt
index 2d07edac099..a9be69fd58f 100644
--- a/idea/testData/checker/regression/ClassDeclarationAsExpression2.kt
+++ b/idea/testData/checker/regression/ClassDeclarationAsExpression2.kt
@@ -1 +1,3 @@
+// FIR_COMPARISON
+
 fun g() = 1 < <error>class A</error>
\ No newline at end of file
diff --git a/idea/testData/checker/regression/ClassDeclarationAsExpression3.kt b/idea/testData/checker/regression/ClassDeclarationAsExpression3.kt
index b0b3a1847bf..273083550f4 100644
--- a/idea/testData/checker/regression/ClassDeclarationAsExpression3.kt
+++ b/idea/testData/checker/regression/ClassDeclarationAsExpression3.kt
@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 fun f(<warning>i</warning>: Int = 3 < <error>class A {
     fun f() {
         f()
diff --git a/idea/testData/checker/regression/DestructuringDeclarationInLambda.kt b/idea/testData/checker/regression/DestructuringDeclarationInLambda.kt
index a181daf6143..6e7dcf0a66c 100644
--- a/idea/testData/checker/regression/DestructuringDeclarationInLambda.kt
+++ b/idea/testData/checker/regression/DestructuringDeclarationInLambda.kt
@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 data class XY(val x: Int, val y: Int)
 
 fun convert(xy: XY, f: (XY) -> Int) = f(xy)
diff --git a/idea/testData/checker/regression/DollarsInName.kt b/idea/testData/checker/regression/DollarsInName.kt
index ccb8340e2f9..df0370d7727 100644
--- a/idea/testData/checker/regression/DollarsInName.kt
+++ b/idea/testData/checker/regression/DollarsInName.kt
@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 class `A$B` {
     class `$$$` {
         class `$`
diff --git a/idea/testData/checker/regression/FunctionTypes.kt b/idea/testData/checker/regression/FunctionTypes.kt
index 79dfe2ba111..b3d7eadf586 100644
--- a/idea/testData/checker/regression/FunctionTypes.kt
+++ b/idea/testData/checker/regression/FunctionTypes.kt
@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 fun <K, V> intercept(<warning>block</warning>: (key: K, next: (K) -> V, K) -> V) {
 }
 
diff --git a/idea/testData/checker/regression/Jet124.kt b/idea/testData/checker/regression/Jet124.kt
index 6fa400a1acc..c0e02d7503a 100644
--- a/idea/testData/checker/regression/Jet124.kt
+++ b/idea/testData/checker/regression/Jet124.kt
@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 fun foo1() :  (Int) -> Int = { x: Int -> x }
 
 fun foo() {
diff --git a/idea/testData/checker/regression/Jet169.kt b/idea/testData/checker/regression/Jet169.kt
index e38e1eb9a05..0184765c3c5 100644
--- a/idea/testData/checker/regression/Jet169.kt
+++ b/idea/testData/checker/regression/Jet169.kt
@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 fun set(<warning>key</warning> : String, <warning>value</warning> : String) {
   val a : String? = ""
   when (a) {
diff --git a/idea/testData/checker/regression/Jet183-1.kt b/idea/testData/checker/regression/Jet183-1.kt
index 256cb1cec68..fb4cfa5464e 100644
--- a/idea/testData/checker/regression/Jet183-1.kt
+++ b/idea/testData/checker/regression/Jet183-1.kt
@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 enum class ProtocolState {
   WAITING {
     override fun signal() = ProtocolState.TALKING
diff --git a/idea/testData/checker/regression/Jet183.kt b/idea/testData/checker/regression/Jet183.kt
index 0b4ec222520..f308938215a 100644
--- a/idea/testData/checker/regression/Jet183.kt
+++ b/idea/testData/checker/regression/Jet183.kt
@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 enum class ProtocolState {
   WAITING {
     override fun signal() = ProtocolState.TALKING
diff --git a/idea/testData/checker/regression/Jet53.kt b/idea/testData/checker/regression/Jet53.kt
index bb638c90294..662e006a385 100644
--- a/idea/testData/checker/regression/Jet53.kt
+++ b/idea/testData/checker/regression/Jet53.kt
@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 import java.util.Collections
 
 fun <T> checkSubtype(t: T) = t
diff --git a/idea/testData/checker/regression/Jet67.kt b/idea/testData/checker/regression/Jet67.kt
index 94549ab8df9..d06b8eed039 100644
--- a/idea/testData/checker/regression/Jet67.kt
+++ b/idea/testData/checker/regression/Jet67.kt
@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 abstract class XXX {
   abstract val a : Int get
 
diff --git a/idea/testData/checker/regression/Jet68.kt b/idea/testData/checker/regression/Jet68.kt
index 2d9cc4c7b21..fffa246c6e3 100644
--- a/idea/testData/checker/regression/Jet68.kt
+++ b/idea/testData/checker/regression/Jet68.kt
@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 class Foo()
 
 fun test() {
diff --git a/idea/testData/checker/regression/Jet69.kt b/idea/testData/checker/regression/Jet69.kt
index a83894fbebe..80e88d894b5 100644
--- a/idea/testData/checker/regression/Jet69.kt
+++ b/idea/testData/checker/regression/Jet69.kt
@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 class Command() {}
 
 fun parse(<warning>cmd</warning>: String): Command? { return null  }
diff --git a/idea/testData/checker/regression/Jet72.kt b/idea/testData/checker/regression/Jet72.kt
index 0e08d7e23a5..e0f32c079e6 100644
--- a/idea/testData/checker/regression/Jet72.kt
+++ b/idea/testData/checker/regression/Jet72.kt
@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 // JET-72 Type inference doesn't work when iterating over ArrayList
 
 import java.util.ArrayList
diff --git a/idea/testData/checker/regression/OverrideResolution.kt b/idea/testData/checker/regression/OverrideResolution.kt
index 16ae0bf07b1..2392d370b12 100644
--- a/idea/testData/checker/regression/OverrideResolution.kt
+++ b/idea/testData/checker/regression/OverrideResolution.kt
@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 fun box() {
     val a : C = C()
     a.foo()
diff --git a/idea/testData/checker/regression/ScopeForSecondaryConstructors.kt b/idea/testData/checker/regression/ScopeForSecondaryConstructors.kt
index 8c79b0ca048..e542461041e 100644
--- a/idea/testData/checker/regression/ScopeForSecondaryConstructors.kt
+++ b/idea/testData/checker/regression/ScopeForSecondaryConstructors.kt
@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 fun <T> checkSubtype(t: T) = t
 
 class Foo(var bar : Int, var barr : Int, var barrr : Int) {
diff --git a/idea/testData/checker/regression/SpecififcityByReceiver.kt b/idea/testData/checker/regression/SpecififcityByReceiver.kt
index 5e1c2d4e331..6fa40fe3a47 100644
--- a/idea/testData/checker/regression/SpecififcityByReceiver.kt
+++ b/idea/testData/checker/regression/SpecififcityByReceiver.kt
@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 fun Any.<warning>equals</warning>(<warning>other</warning> : Any?) : Boolean = true
 
 fun main(args: Array<String>) {
diff --git a/idea/testData/checker/regression/extensionMemberInClassObject.kt b/idea/testData/checker/regression/extensionMemberInClassObject.kt
index 4e5a137e04c..4ef0359c9c0 100644
--- a/idea/testData/checker/regression/extensionMemberInClassObject.kt
+++ b/idea/testData/checker/regression/extensionMemberInClassObject.kt
@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 interface Bar {
     fun <T> T.bar() {}
 }
diff --git a/idea/testData/checker/regression/objectLiteralInSupertypeList.kt b/idea/testData/checker/regression/objectLiteralInSupertypeList.kt
index 64728b18d95..b652f417b69 100644
--- a/idea/testData/checker/regression/objectLiteralInSupertypeList.kt
+++ b/idea/testData/checker/regression/objectLiteralInSupertypeList.kt
@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 interface A
 
 open class B(<warning>i</warning>: Int, <warning>a</warning>: A)
diff --git a/idea/tests/org/jetbrains/kotlin/checkers/AbstractFirPsiCheckerTest.kt b/idea/tests/org/jetbrains/kotlin/checkers/AbstractFirPsiCheckerTest.kt
index adf5f77d8e9..dda0ad66591 100644
--- a/idea/tests/org/jetbrains/kotlin/checkers/AbstractFirPsiCheckerTest.kt
+++ b/idea/tests/org/jetbrains/kotlin/checkers/AbstractFirPsiCheckerTest.kt
@@ -9,6 +9,8 @@ import com.intellij.rt.execution.junit.FileComparisonFailure
 import org.jetbrains.kotlin.idea.fir.FirResolution
 import org.jetbrains.kotlin.idea.test.configureCompilerOptions
 import org.jetbrains.kotlin.idea.test.rollbackCompilerOptions
+import org.jetbrains.kotlin.test.InTextDirectivesUtils
+import java.io.File
 
 abstract class AbstractFirPsiCheckerTest : AbstractPsiCheckerTest() {
     override fun setUp() {
@@ -28,11 +30,17 @@ abstract class AbstractFirPsiCheckerTest : AbstractPsiCheckerTest() {
     ): Long {
         val file = file
         val configured = configureCompilerOptions(file.text, project, module)
+        val doComparison = InTextDirectivesUtils.isDirectiveDefined(myFixture.file.text, "FIR_COMPARISON")
         return try {
             myFixture.checkHighlighting(checkWarnings, checkInfos, checkWeakWarnings)
         } catch (e: FileComparisonFailure) {
-            // NB: yet we do not actually compare highlighting
-            0
+            if (doComparison) {
+                // Even this is very partial check (only error compatibility, no warnings / infos)
+                throw FileComparisonFailure(e.message, e.expected, e.actual, File(e.filePath).absolutePath)
+            } else {
+                // Here we just check that we haven't crashed due to exception
+                0
+            }
         } finally {
             if (configured) {
                 rollbackCompilerOptions(project, module)