diff --git a/compiler/testData/diagnostics/tests/variance/InPosition.fir.kt b/compiler/testData/diagnostics/tests/variance/InPosition.fir.kt
index f1c532ff27c..a6700c0f240 100644
--- a/compiler/testData/diagnostics/tests/variance/InPosition.fir.kt
+++ b/compiler/testData/diagnostics/tests/variance/InPosition.fir.kt
@@ -1,3 +1,5 @@
+// !LANGUAGE: -TrailingCommas
+
 interface In<in T>
 interface Out<out T>
 interface Inv<T>
diff --git a/compiler/testData/diagnostics/tests/variance/InPosition.kt b/compiler/testData/diagnostics/tests/variance/InPosition.kt
index d43e21c1949..b5b8e51a7bc 100644
--- a/compiler/testData/diagnostics/tests/variance/InPosition.kt
+++ b/compiler/testData/diagnostics/tests/variance/InPosition.kt
@@ -1,3 +1,5 @@
+// !LANGUAGE: -TrailingCommas
+
 interface In<in T>
 interface Out<out T>
 interface Inv<T>
diff --git a/compiler/testData/diagnostics/tests/variance/InvariantPosition.fir.kt b/compiler/testData/diagnostics/tests/variance/InvariantPosition.fir.kt
index 324b1c9f631..cadf0d1db0e 100644
--- a/compiler/testData/diagnostics/tests/variance/InvariantPosition.fir.kt
+++ b/compiler/testData/diagnostics/tests/variance/InvariantPosition.fir.kt
@@ -1,3 +1,5 @@
+// !LANGUAGE: -TrailingCommas
+
 interface In<in T>
 interface Out<out T>
 interface Inv<T>
diff --git a/compiler/testData/diagnostics/tests/variance/InvariantPosition.kt b/compiler/testData/diagnostics/tests/variance/InvariantPosition.kt
index 94e6e1ba005..008381f6084 100644
--- a/compiler/testData/diagnostics/tests/variance/InvariantPosition.kt
+++ b/compiler/testData/diagnostics/tests/variance/InvariantPosition.kt
@@ -1,3 +1,5 @@
+// !LANGUAGE: -TrailingCommas
+
 interface In<in T>
 interface Out<out T>
 interface Inv<T>
diff --git a/compiler/testData/diagnostics/tests/variance/OutPosition.fir.kt b/compiler/testData/diagnostics/tests/variance/OutPosition.fir.kt
index 287332912c6..87ee9d31e5f 100644
--- a/compiler/testData/diagnostics/tests/variance/OutPosition.fir.kt
+++ b/compiler/testData/diagnostics/tests/variance/OutPosition.fir.kt
@@ -1,3 +1,5 @@
+// !LANGUAGE: -TrailingCommas
+
 interface In<in T>
 interface Out<out T>
 interface Inv<T>
diff --git a/compiler/testData/diagnostics/tests/variance/OutPosition.kt b/compiler/testData/diagnostics/tests/variance/OutPosition.kt
index e4848e9e3ed..274e5a7e2e8 100644
--- a/compiler/testData/diagnostics/tests/variance/OutPosition.kt
+++ b/compiler/testData/diagnostics/tests/variance/OutPosition.kt
@@ -1,3 +1,5 @@
+// !LANGUAGE: -TrailingCommas
+
 interface In<in T>
 interface Out<out T>
 interface Inv<T>
diff --git a/compiler/testData/diagnostics/testsWithStdLib/trailingComma/multiVariableDeclarationWithDisabledFeature.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/trailingComma/multiVariableDeclarationWithDisabledFeature.fir.kt
index 0238b3d455e..29d20d7649f 100644
--- a/compiler/testData/diagnostics/testsWithStdLib/trailingComma/multiVariableDeclarationWithDisabledFeature.fir.kt
+++ b/compiler/testData/diagnostics/testsWithStdLib/trailingComma/multiVariableDeclarationWithDisabledFeature.fir.kt
@@ -1,4 +1,5 @@
 // !DIAGNOSTICS: -UNUSED_VARIABLE, -UNUSED_DESTRUCTURED_PARAMETER_ENTRY, -UNUSED_ANONYMOUS_PARAMETER
+// !LANGUAGE: -TrailingCommas
 
 data class Foo1(val x: String, val y: String, val z: String = "")
 
diff --git a/compiler/testData/diagnostics/testsWithStdLib/trailingComma/multiVariableDeclarationWithDisabledFeature.kt b/compiler/testData/diagnostics/testsWithStdLib/trailingComma/multiVariableDeclarationWithDisabledFeature.kt
index 37c1ef2db78..c76821f275e 100644
--- a/compiler/testData/diagnostics/testsWithStdLib/trailingComma/multiVariableDeclarationWithDisabledFeature.kt
+++ b/compiler/testData/diagnostics/testsWithStdLib/trailingComma/multiVariableDeclarationWithDisabledFeature.kt
@@ -1,4 +1,5 @@
 // !DIAGNOSTICS: -UNUSED_VARIABLE, -UNUSED_DESTRUCTURED_PARAMETER_ENTRY, -UNUSED_ANONYMOUS_PARAMETER
+// !LANGUAGE: -TrailingCommas
 
 data class Foo1(val x: String, val y: String, val z: String = "")
 
diff --git a/compiler/testData/diagnostics/testsWithStdLib/trailingComma/typeArgumentsWithDisabledFeature.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/trailingComma/typeArgumentsWithDisabledFeature.fir.kt
index 7d12e9427a7..eb57700be0c 100644
--- a/compiler/testData/diagnostics/testsWithStdLib/trailingComma/typeArgumentsWithDisabledFeature.fir.kt
+++ b/compiler/testData/diagnostics/testsWithStdLib/trailingComma/typeArgumentsWithDisabledFeature.fir.kt
@@ -1,4 +1,5 @@
 // !DIAGNOSTICS: -UNUSED_VARIABLE, -UNUSED_TYPEALIAS_PARAMETER, -CAST_NEVER_SUCCEEDS
+// !LANGUAGE: -TrailingCommas
 
 class Foo1<T1> {}
 
diff --git a/compiler/testData/diagnostics/testsWithStdLib/trailingComma/typeArgumentsWithDisabledFeature.kt b/compiler/testData/diagnostics/testsWithStdLib/trailingComma/typeArgumentsWithDisabledFeature.kt
index f6b4020ad2c..db90d501d2d 100644
--- a/compiler/testData/diagnostics/testsWithStdLib/trailingComma/typeArgumentsWithDisabledFeature.kt
+++ b/compiler/testData/diagnostics/testsWithStdLib/trailingComma/typeArgumentsWithDisabledFeature.kt
@@ -1,4 +1,5 @@
 // !DIAGNOSTICS: -UNUSED_VARIABLE, -UNUSED_TYPEALIAS_PARAMETER, -CAST_NEVER_SUCCEEDS
+// !LANGUAGE: -TrailingCommas
 
 class Foo1<T1> {}
 
diff --git a/compiler/testData/diagnostics/testsWithStdLib/trailingComma/typeParametersWithDisabledFeature.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/trailingComma/typeParametersWithDisabledFeature.fir.kt
index a6b085bd057..d6af5620c67 100644
--- a/compiler/testData/diagnostics/testsWithStdLib/trailingComma/typeParametersWithDisabledFeature.fir.kt
+++ b/compiler/testData/diagnostics/testsWithStdLib/trailingComma/typeParametersWithDisabledFeature.fir.kt
@@ -1,4 +1,5 @@
 // !DIAGNOSTICS: -UNUSED_PARAMETER, -UNUSED_TYPEALIAS_PARAMETER
+// !LANGUAGE: -TrailingCommas
 
 @Target(AnnotationTarget.TYPE)
 annotation class Anno
diff --git a/compiler/testData/diagnostics/testsWithStdLib/trailingComma/typeParametersWithDisabledFeature.kt b/compiler/testData/diagnostics/testsWithStdLib/trailingComma/typeParametersWithDisabledFeature.kt
index f37a8147271..af5920cbc94 100644
--- a/compiler/testData/diagnostics/testsWithStdLib/trailingComma/typeParametersWithDisabledFeature.kt
+++ b/compiler/testData/diagnostics/testsWithStdLib/trailingComma/typeParametersWithDisabledFeature.kt
@@ -1,4 +1,5 @@
 // !DIAGNOSTICS: -UNUSED_PARAMETER, -UNUSED_TYPEALIAS_PARAMETER
+// !LANGUAGE: -TrailingCommas
 
 @Target(AnnotationTarget.TYPE)
 annotation class Anno
diff --git a/compiler/testData/diagnostics/testsWithStdLib/trailingComma/valueArgumentsWithDisabledFeature.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/trailingComma/valueArgumentsWithDisabledFeature.fir.kt
index 989def7b079..b1d31470489 100644
--- a/compiler/testData/diagnostics/testsWithStdLib/trailingComma/valueArgumentsWithDisabledFeature.fir.kt
+++ b/compiler/testData/diagnostics/testsWithStdLib/trailingComma/valueArgumentsWithDisabledFeature.fir.kt
@@ -1,4 +1,5 @@
 // !DIAGNOSTICS: -UNUSED_PARAMETER, -UNUSED_VARIABLE, -UNUSED_ANONYMOUS_PARAMETER
+// !LANGUAGE: -TrailingCommas
 
 @Target(AnnotationTarget.TYPE)
 annotation class Anno1(val x: IntArray)
diff --git a/compiler/testData/diagnostics/testsWithStdLib/trailingComma/valueArgumentsWithDisabledFeature.kt b/compiler/testData/diagnostics/testsWithStdLib/trailingComma/valueArgumentsWithDisabledFeature.kt
index fee2116615f..598bfd2bd26 100644
--- a/compiler/testData/diagnostics/testsWithStdLib/trailingComma/valueArgumentsWithDisabledFeature.kt
+++ b/compiler/testData/diagnostics/testsWithStdLib/trailingComma/valueArgumentsWithDisabledFeature.kt
@@ -1,4 +1,5 @@
 // !DIAGNOSTICS: -UNUSED_PARAMETER, -UNUSED_VARIABLE, -UNUSED_ANONYMOUS_PARAMETER
+// !LANGUAGE: -TrailingCommas
 
 @Target(AnnotationTarget.TYPE)
 annotation class Anno1(val x: IntArray)
diff --git a/compiler/testData/diagnostics/testsWithStdLib/trailingComma/valueParametersWithDisabledFeature.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/trailingComma/valueParametersWithDisabledFeature.fir.kt
index 24092568b53..553dd90b15e 100644
--- a/compiler/testData/diagnostics/testsWithStdLib/trailingComma/valueParametersWithDisabledFeature.fir.kt
+++ b/compiler/testData/diagnostics/testsWithStdLib/trailingComma/valueParametersWithDisabledFeature.fir.kt
@@ -1,4 +1,5 @@
 // !DIAGNOSTICS: -UNUSED_PARAMETER, -UNUSED_ANONYMOUS_PARAMETER -UNUSED_VARIABLE
+// !LANGUAGE: -TrailingCommas
 
 open class Foo1(x: Int = 10, y: Float = 0f,)
 
diff --git a/compiler/testData/diagnostics/testsWithStdLib/trailingComma/valueParametersWithDisabledFeature.kt b/compiler/testData/diagnostics/testsWithStdLib/trailingComma/valueParametersWithDisabledFeature.kt
index 2d63ccc239f..2105498d52b 100644
--- a/compiler/testData/diagnostics/testsWithStdLib/trailingComma/valueParametersWithDisabledFeature.kt
+++ b/compiler/testData/diagnostics/testsWithStdLib/trailingComma/valueParametersWithDisabledFeature.kt
@@ -1,4 +1,5 @@
 // !DIAGNOSTICS: -UNUSED_PARAMETER, -UNUSED_ANONYMOUS_PARAMETER -UNUSED_VARIABLE
+// !LANGUAGE: -TrailingCommas
 
 open class Foo1(x: Int = 10, y: Float = 0f<!UNSUPPORTED_FEATURE!>,<!>)
 
diff --git a/compiler/testData/diagnostics/testsWithStdLib/trailingComma/whenEntryWithDisabledFeature.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/trailingComma/whenEntryWithDisabledFeature.fir.kt
index 46094fed33d..f2c3b8c94ad 100644
--- a/compiler/testData/diagnostics/testsWithStdLib/trailingComma/whenEntryWithDisabledFeature.fir.kt
+++ b/compiler/testData/diagnostics/testsWithStdLib/trailingComma/whenEntryWithDisabledFeature.fir.kt
@@ -1,4 +1,5 @@
 // !DIAGNOSTICS: -UNUSED_VARIABLE, -UNUSED_EXPRESSION -NAME_SHADOWING
+// !LANGUAGE: -TrailingCommas
 
 fun foo1(x: Any) = when (x) {
     Comparable::class,
diff --git a/compiler/testData/diagnostics/testsWithStdLib/trailingComma/whenEntryWithDisabledFeature.kt b/compiler/testData/diagnostics/testsWithStdLib/trailingComma/whenEntryWithDisabledFeature.kt
index 80cee86541b..cae0538f73d 100644
--- a/compiler/testData/diagnostics/testsWithStdLib/trailingComma/whenEntryWithDisabledFeature.kt
+++ b/compiler/testData/diagnostics/testsWithStdLib/trailingComma/whenEntryWithDisabledFeature.kt
@@ -1,4 +1,5 @@
 // !DIAGNOSTICS: -UNUSED_VARIABLE, -UNUSED_EXPRESSION -NAME_SHADOWING
+// !LANGUAGE: -TrailingCommas
 
 fun foo1(x: Any) = when (x) {
     Comparable::class,