diff --git a/compiler/testData/diagnostics/klibSerializationTests/signatureClashClasses.diag.txt b/compiler/testData/diagnostics/klibSerializationTests/signatureClashClasses.diag.txt
new file mode 100644
index 00000000000..da78d5dbccf
--- /dev/null
+++ b/compiler/testData/diagnostics/klibSerializationTests/signatureClashClasses.diag.txt
@@ -0,0 +1,7 @@
+/main.kt:27:5: error: Platform declaration clash: The following declarations have the same IR signature (com.example.klib.serialization.diagnostics/ConstructorsClash.<init>|<init>(kotlin.Int){}[0]):
+    constructor ConstructorsClash(s: kotlin.Int) defined in com.example.klib.serialization.diagnostics.ConstructorsClash
+    constructor ConstructorsClash(s: kotlin.Int) defined in com.example.klib.serialization.diagnostics.ConstructorsClash
+
+/main.kt:29:5: error: Platform declaration clash: The following declarations have the same IR signature (com.example.klib.serialization.diagnostics/ConstructorsClash.<init>|<init>(kotlin.Int){}[0]):
+    constructor ConstructorsClash(s: kotlin.Int) defined in com.example.klib.serialization.diagnostics.ConstructorsClash
+    constructor ConstructorsClash(s: kotlin.Int) defined in com.example.klib.serialization.diagnostics.ConstructorsClash
diff --git a/compiler/testData/diagnostics/klibSerializationTests/signatureClashClasses.kt b/compiler/testData/diagnostics/klibSerializationTests/signatureClashClasses.kt
new file mode 100644
index 00000000000..f54623fcb8e
--- /dev/null
+++ b/compiler/testData/diagnostics/klibSerializationTests/signatureClashClasses.kt
@@ -0,0 +1,31 @@
+// WITH_STDLIB
+// DIAGNOSTICS: -ERROR_SUPPRESSION
+// FIR_IDENTICAL
+// RENDER_ALL_DIAGNOSTICS_FULL_TEXT
+
+// IGNORE_BACKEND: JS_IR, NATIVE
+// ^ KT-65680: Class redeclaration leads to BackendException during IR fake override builder
+
+// MODULE: lib
+package com.example.klib.serialization.diagnostics
+
+class SeparateModules
+
+// MODULE: main(lib)
+// FILE: foo.kt
+package com.example.klib.serialization.diagnostics
+
+class SeparateModules
+
+<!CONFLICTING_KLIB_SIGNATURES_ERROR, CONFLICTING_KLIB_SIGNATURES_ERROR!>@Suppress("PACKAGE_OR_CLASSIFIER_REDECLARATION") class SeparateFiles<!>
+
+// FILE: main.kt
+package com.example.klib.serialization.diagnostics
+
+<!CONFLICTING_KLIB_SIGNATURES_ERROR, CONFLICTING_KLIB_SIGNATURES_ERROR!>@Suppress("PACKAGE_OR_CLASSIFIER_REDECLARATION") class SeparateFiles<!>
+
+class ConstructorsClash {
+    <!CONFLICTING_KLIB_SIGNATURES_ERROR!>@Deprecated(message = "", level = DeprecationLevel.HIDDEN)
+    constructor(s: Int)<!>
+    <!CONFLICTING_KLIB_SIGNATURES_ERROR!>constructor(s: Int)<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/klibSerializationTests/signatureClash.diag.txt b/compiler/testData/diagnostics/klibSerializationTests/signatureClashFunctions.diag.txt
similarity index 53%
rename from compiler/testData/diagnostics/klibSerializationTests/signatureClash.diag.txt
rename to compiler/testData/diagnostics/klibSerializationTests/signatureClashFunctions.diag.txt
index 927825e554d..977f1837b07 100644
--- a/compiler/testData/diagnostics/klibSerializationTests/signatureClash.diag.txt
+++ b/compiler/testData/diagnostics/klibSerializationTests/signatureClashFunctions.diag.txt
@@ -1,64 +1,30 @@
-/foo.kt:14:1: error: Platform declaration clash: The following functions have the same IR signature (com.example.klib.serialization.diagnostics/foo|foo(){}[0]):
+/foo.kt:16:1: error: Platform declaration clash: The following functions have the same IR signature (com.example.klib.serialization.diagnostics/foo|foo(){}[0]):
     fun foo(): kotlin.Long defined in com.example.klib.serialization.diagnostics
     fun foo(): kotlin.String defined in com.example.klib.serialization.diagnostics
     fun foo(): kotlin.Int defined in com.example.klib.serialization.diagnostics
 
-/foo.kt:17:1: error: Platform declaration clash: The following properties have the same IR signature (com.example.klib.serialization.diagnostics/myVal|{}myVal[0]):
-    val myVal: kotlin.String defined in com.example.klib.serialization.diagnostics
-    var myVal: kotlin.Int defined in com.example.klib.serialization.diagnostics
-    var myVal: kotlin.Long defined in com.example.klib.serialization.diagnostics
+/foo.kt:19:1: error: Platform declaration clash: The following functions have the same IR signature (com.example.klib.serialization.diagnostics/topLevelParametrized|topLevelParametrized@0:0(0:1){0§<kotlin.Any?>;1§<kotlin.Any?>}[0]):
+    fun <T, K> T.topLevelParametrized(s: K): T defined in com.example.klib.serialization.diagnostics
+    fun <T, K> T.topLevelParametrized(s: K): T defined in com.example.klib.serialization.diagnostics
 
-/foo.kt:17:1: error: Platform declaration clash: The following functions have the same IR signature (com.example.klib.serialization.diagnostics/myVal.<get-myVal>|<get-myVal>(){}[0]):
-    fun `<get-myVal>`(): kotlin.Int defined in com.example.klib.serialization.diagnostics
-    fun `<get-myVal>`(): kotlin.Long defined in com.example.klib.serialization.diagnostics
-    fun `<get-myVal>`(): kotlin.String defined in com.example.klib.serialization.diagnostics
+/foo.kt:22:1: error: Platform declaration clash: The following functions have the same IR signature (com.example.klib.serialization.diagnostics/topLevelInternalVararg|topLevelInternalVararg(kotlin.IntArray...){}[0]):
+    fun topLevelInternalVararg(vararg i: kotlin.Int): kotlin.Int defined in com.example.klib.serialization.diagnostics
+    fun topLevelInternalVararg(vararg i: kotlin.Int): kotlin.Int defined in com.example.klib.serialization.diagnostics
 
-/foo.kt:19:1: error: Platform declaration clash: The following properties have the same IR signature (com.example.klib.serialization.diagnostics/myDelegated|{}myDelegated[0]):
-    val myDelegated: kotlin.Int defined in com.example.klib.serialization.diagnostics
-    val myDelegated: kotlin.Long defined in com.example.klib.serialization.diagnostics
+/foo.kt:26:1: error: Platform declaration clash: The following functions have the same IR signature (com.example.klib.serialization.diagnostics/typealiasReciever|typealiasReciever@kotlin.collections.Map<kotlin.String,kotlin.Int>(){}[0]):
+    fun kotlin.collections.Map<kotlin.String, kotlin.Int>.typealiasReciever(): kotlin.Int defined in com.example.klib.serialization.diagnostics
+    fun kotlin.collections.Map<kotlin.String, kotlin.Int>.typealiasReciever(): kotlin.Int defined in com.example.klib.serialization.diagnostics
 
-/foo.kt:19:26: error: Platform declaration clash: The following functions have the same IR signature (com.example.klib.serialization.diagnostics/myDelegated.<get-myDelegated>|<get-myDelegated>(){}[0]):
-    fun `<get-myDelegated>`(): kotlin.Int defined in com.example.klib.serialization.diagnostics
-    fun `<get-myDelegated>`(): kotlin.Long defined in com.example.klib.serialization.diagnostics
-
-/main.kt:24:1: error: Platform declaration clash: The following functions have the same IR signature (com.example.klib.serialization.diagnostics/foo|foo(){}[0]):
+/main.kt:34:1: error: Platform declaration clash: The following functions have the same IR signature (com.example.klib.serialization.diagnostics/foo|foo(){}[0]):
     fun foo(): kotlin.Long defined in com.example.klib.serialization.diagnostics
     fun foo(): kotlin.String defined in com.example.klib.serialization.diagnostics
     fun foo(): kotlin.Int defined in com.example.klib.serialization.diagnostics
 
-/main.kt:27:1: error: Platform declaration clash: The following functions have the same IR signature (com.example.klib.serialization.diagnostics/foo|foo(){}[0]):
+/main.kt:37:1: error: Platform declaration clash: The following functions have the same IR signature (com.example.klib.serialization.diagnostics/foo|foo(){}[0]):
     fun foo(): kotlin.Long defined in com.example.klib.serialization.diagnostics
     fun foo(): kotlin.String defined in com.example.klib.serialization.diagnostics
     fun foo(): kotlin.Int defined in com.example.klib.serialization.diagnostics
 
-/main.kt:29:1: error: Platform declaration clash: The following properties have the same IR signature (com.example.klib.serialization.diagnostics/myVal|{}myVal[0]):
-    val myVal: kotlin.String defined in com.example.klib.serialization.diagnostics
-    var myVal: kotlin.Int defined in com.example.klib.serialization.diagnostics
-    var myVal: kotlin.Long defined in com.example.klib.serialization.diagnostics
-
-/main.kt:29:1: error: Platform declaration clash: The following functions have the same IR signature (com.example.klib.serialization.diagnostics/myVal.<get-myVal>|<get-myVal>(){}[0]):
-    fun `<get-myVal>`(): kotlin.Int defined in com.example.klib.serialization.diagnostics
-    fun `<get-myVal>`(): kotlin.Long defined in com.example.klib.serialization.diagnostics
-    fun `<get-myVal>`(): kotlin.String defined in com.example.klib.serialization.diagnostics
-
-/main.kt:32:1: error: Platform declaration clash: The following properties have the same IR signature (com.example.klib.serialization.diagnostics/myVal|{}myVal[0]):
-    val myVal: kotlin.String defined in com.example.klib.serialization.diagnostics
-    var myVal: kotlin.Int defined in com.example.klib.serialization.diagnostics
-    var myVal: kotlin.Long defined in com.example.klib.serialization.diagnostics
-
-/main.kt:34:1: error: Platform declaration clash: The following functions have the same IR signature (com.example.klib.serialization.diagnostics/myVal.<get-myVal>|<get-myVal>(){}[0]):
-    fun `<get-myVal>`(): kotlin.Int defined in com.example.klib.serialization.diagnostics
-    fun `<get-myVal>`(): kotlin.Long defined in com.example.klib.serialization.diagnostics
-    fun `<get-myVal>`(): kotlin.String defined in com.example.klib.serialization.diagnostics
-
-/main.kt:36:1: error: Platform declaration clash: The following properties have the same IR signature (com.example.klib.serialization.diagnostics/myDelegated|{}myDelegated[0]):
-    val myDelegated: kotlin.Int defined in com.example.klib.serialization.diagnostics
-    val myDelegated: kotlin.Long defined in com.example.klib.serialization.diagnostics
-
-/main.kt:37:25: error: Platform declaration clash: The following functions have the same IR signature (com.example.klib.serialization.diagnostics/myDelegated.<get-myDelegated>|<get-myDelegated>(){}[0]):
-    fun `<get-myDelegated>`(): kotlin.Int defined in com.example.klib.serialization.diagnostics
-    fun `<get-myDelegated>`(): kotlin.Long defined in com.example.klib.serialization.diagnostics
-
 /main.kt:43:5: error: Platform declaration clash: The following functions have the same IR signature (com.example.klib.serialization.diagnostics/A.parameterized|parameterized(0:0){0§<kotlin.Any?>}[0]):
     fun <T> parameterized(a: T): T defined in com.example.klib.serialization.diagnostics.A
     fun <T> parameterized(a: T): kotlin.Unit defined in com.example.klib.serialization.diagnostics.A
@@ -90,3 +56,15 @@
 /main.kt:70:1: error: Platform declaration clash: The following functions have the same IR signature (com.example.klib.serialization.diagnostics/bar|bar(){}[0]):
     fun bar(): kotlin.Long defined in com.example.klib.serialization.diagnostics
     fun bar(): kotlin.Long defined in com.example.klib.serialization.diagnostics
+
+/main.kt:72:1: error: Platform declaration clash: The following functions have the same IR signature (com.example.klib.serialization.diagnostics/topLevelParametrized|topLevelParametrized@0:0(0:1){0§<kotlin.Any?>;1§<kotlin.Any?>}[0]):
+    fun <T, K> T.topLevelParametrized(s: K): T defined in com.example.klib.serialization.diagnostics
+    fun <T, K> T.topLevelParametrized(s: K): T defined in com.example.klib.serialization.diagnostics
+
+/main.kt:75:1: error: Platform declaration clash: The following functions have the same IR signature (com.example.klib.serialization.diagnostics/topLevelInternalVararg|topLevelInternalVararg(kotlin.IntArray...){}[0]):
+    fun topLevelInternalVararg(vararg i: kotlin.Int): kotlin.Int defined in com.example.klib.serialization.diagnostics
+    fun topLevelInternalVararg(vararg i: kotlin.Int): kotlin.Int defined in com.example.klib.serialization.diagnostics
+
+/main.kt:78:1: error: Platform declaration clash: The following functions have the same IR signature (com.example.klib.serialization.diagnostics/typealiasReciever|typealiasReciever@kotlin.collections.Map<kotlin.String,kotlin.Int>(){}[0]):
+    fun kotlin.collections.Map<kotlin.String, kotlin.Int>.typealiasReciever(): kotlin.Int defined in com.example.klib.serialization.diagnostics
+    fun kotlin.collections.Map<kotlin.String, kotlin.Int>.typealiasReciever(): kotlin.Int defined in com.example.klib.serialization.diagnostics
diff --git a/compiler/testData/diagnostics/klibSerializationTests/signatureClash.kt b/compiler/testData/diagnostics/klibSerializationTests/signatureClashFunctions.kt
similarity index 71%
rename from compiler/testData/diagnostics/klibSerializationTests/signatureClash.kt
rename to compiler/testData/diagnostics/klibSerializationTests/signatureClashFunctions.kt
index 387b52bc7d7..f6635a9ec86 100644
--- a/compiler/testData/diagnostics/klibSerializationTests/signatureClash.kt
+++ b/compiler/testData/diagnostics/klibSerializationTests/signatureClashFunctions.kt
@@ -11,31 +11,31 @@ fun movedToLib() {}
 // FILE: foo.kt
 package com.example.klib.serialization.diagnostics
 
+private fun privateFunSeparateFiles() = Unit
+
 <!CONFLICTING_KLIB_SIGNATURES_ERROR!>@Deprecated("", level = DeprecationLevel.HIDDEN)
 fun foo(): Long = 0L<!>
 
-<!CONFLICTING_KLIB_SIGNATURES_ERROR, CONFLICTING_KLIB_SIGNATURES_ERROR!>var myVal: Long = 0L<!>
+<!CONFLICTING_KLIB_SIGNATURES_ERROR!>@Deprecated("", level = DeprecationLevel.HIDDEN)
+fun <T, K> T.topLevelParametrized(s: K): T = TODO()<!>
 
-<!CONFLICTING_KLIB_SIGNATURES_ERROR!>val myDelegated: Long by <!CONFLICTING_KLIB_SIGNATURES_ERROR!>lazy { 0L }<!><!>
+<!CONFLICTING_KLIB_SIGNATURES_ERROR!>@Deprecated("", level = DeprecationLevel.HIDDEN)
+internal fun topLevelInternalVararg(vararg i: Int) = 0<!>
+
+typealias S = Map<String, Int>
+<!CONFLICTING_KLIB_SIGNATURES_ERROR!>@Deprecated("", level = DeprecationLevel.HIDDEN)
+fun S.typealiasReciever() = 0<!>
 
 // FILE: main.kt
 package com.example.klib.serialization.diagnostics
 
+private fun privateFunSeparateFiles() = Unit
+
 <!CONFLICTING_KLIB_SIGNATURES_ERROR!>@Deprecated("", level = DeprecationLevel.HIDDEN)
 fun foo(): String = ""<!>
 
 <!CONFLICTING_KLIB_SIGNATURES_ERROR!>fun foo(): Int = 0<!>
 
-<!CONFLICTING_KLIB_SIGNATURES_ERROR, CONFLICTING_KLIB_SIGNATURES_ERROR!>@Deprecated("", level = DeprecationLevel.HIDDEN)
-var myVal: Int = 0<!>
-
-<!CONFLICTING_KLIB_SIGNATURES_ERROR!>@Deprecated("", level = DeprecationLevel.HIDDEN)
-val myVal: String
-<!CONFLICTING_KLIB_SIGNATURES_ERROR!>get() = ""<!><!>
-
-<!CONFLICTING_KLIB_SIGNATURES_ERROR!>@Deprecated("", level = DeprecationLevel.HIDDEN)
-val myDelegated: Int by <!CONFLICTING_KLIB_SIGNATURES_ERROR!>lazy { 1 }<!><!>
-
 @Deprecated("This function moved to the 'lib' module", level = DeprecationLevel.HIDDEN)
 fun movedToLib() {}
 
@@ -68,3 +68,12 @@ fun main() {
 fun bar(): Long = 0L<!>
 
 <!CONFLICTING_KLIB_SIGNATURES_ERROR!>fun bar(): Long = 1L<!>
+
+<!CONFLICTING_KLIB_SIGNATURES_ERROR!>@Deprecated("", level = DeprecationLevel.HIDDEN)
+fun <T, K> T.topLevelParametrized(s: K): T = TODO()<!>
+
+<!CONFLICTING_KLIB_SIGNATURES_ERROR!>@Deprecated("", level = DeprecationLevel.HIDDEN)
+internal fun topLevelInternalVararg(vararg i: Int) = 0<!>
+
+<!CONFLICTING_KLIB_SIGNATURES_ERROR!>@Deprecated("", level = DeprecationLevel.HIDDEN)
+fun Map<String, Int>.typealiasReciever() = 0<!>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/klibSerializationTests/signatureClashVariables.diag.txt b/compiler/testData/diagnostics/klibSerializationTests/signatureClashVariables.diag.txt
new file mode 100644
index 00000000000..0aeccaa2e37
--- /dev/null
+++ b/compiler/testData/diagnostics/klibSerializationTests/signatureClashVariables.diag.txt
@@ -0,0 +1,111 @@
+/foo.kt:18:1: error: Platform declaration clash: The following properties have the same IR signature (com.example.klib.serialization.diagnostics/valueSeparateFiles|{}valueSeparateFiles[0]):
+    val valueSeparateFiles: kotlin.Int defined in com.example.klib.serialization.diagnostics
+    val valueSeparateFiles: kotlin.Int defined in com.example.klib.serialization.diagnostics
+
+/foo.kt:18:1: error: Platform declaration clash: The following functions have the same IR signature (com.example.klib.serialization.diagnostics/valueSeparateFiles.<get-valueSeparateFiles>|<get-valueSeparateFiles>(){}[0]):
+    fun `<get-valueSeparateFiles>`(): kotlin.Int defined in com.example.klib.serialization.diagnostics
+    fun `<get-valueSeparateFiles>`(): kotlin.Int defined in com.example.klib.serialization.diagnostics
+
+/foo.kt:20:1: error: Platform declaration clash: The following properties have the same IR signature (com.example.klib.serialization.diagnostics/myDelegated|{}myDelegated[0]):
+    val myDelegated: kotlin.Int defined in com.example.klib.serialization.diagnostics
+    val myDelegated: kotlin.Long defined in com.example.klib.serialization.diagnostics
+
+/foo.kt:20:53: error: Platform declaration clash: The following functions have the same IR signature (com.example.klib.serialization.diagnostics/myDelegated.<get-myDelegated>|<get-myDelegated>(){}[0]):
+    fun `<get-myDelegated>`(): kotlin.Int defined in com.example.klib.serialization.diagnostics
+    fun `<get-myDelegated>`(): kotlin.Long defined in com.example.klib.serialization.diagnostics
+
+/foo.kt:22:1: error: Platform declaration clash: The following properties have the same IR signature (com.example.klib.serialization.diagnostics/extensionValue|@kotlin.Int{}extensionValue[0]):
+    val kotlin.Int.extensionValue: kotlin.Int defined in com.example.klib.serialization.diagnostics
+    var kotlin.Int.extensionValue: kotlin.Int defined in com.example.klib.serialization.diagnostics
+
+/foo.kt:24:1: error: Platform declaration clash: The following functions have the same IR signature (com.example.klib.serialization.diagnostics/extensionValue.<get-extensionValue>|<get-extensionValue>@kotlin.Int(){}[0]):
+    fun kotlin.Int.`<get-extensionValue>`(): kotlin.Int defined in com.example.klib.serialization.diagnostics
+    fun kotlin.Int.`<get-extensionValue>`(): kotlin.Int defined in com.example.klib.serialization.diagnostics
+
+/main.kt:32:1: error: Platform declaration clash: The following properties have the same IR signature (com.example.klib.serialization.diagnostics/valueSeparateFiles|{}valueSeparateFiles[0]):
+    val valueSeparateFiles: kotlin.Int defined in com.example.klib.serialization.diagnostics
+    val valueSeparateFiles: kotlin.Int defined in com.example.klib.serialization.diagnostics
+
+/main.kt:32:1: error: Platform declaration clash: The following functions have the same IR signature (com.example.klib.serialization.diagnostics/valueSeparateFiles.<get-valueSeparateFiles>|<get-valueSeparateFiles>(){}[0]):
+    fun `<get-valueSeparateFiles>`(): kotlin.Int defined in com.example.klib.serialization.diagnostics
+    fun `<get-valueSeparateFiles>`(): kotlin.Int defined in com.example.klib.serialization.diagnostics
+
+/main.kt:34:1: error: Platform declaration clash: The following properties have the same IR signature (com.example.klib.serialization.diagnostics/valueSingleFile|{}valueSingleFile[0]):
+    val valueSingleFile: kotlin.Int defined in com.example.klib.serialization.diagnostics
+    val valueSingleFile: kotlin.String defined in com.example.klib.serialization.diagnostics
+
+/main.kt:34:1: error: Platform declaration clash: The following functions have the same IR signature (com.example.klib.serialization.diagnostics/valueSingleFile.<get-valueSingleFile>|<get-valueSingleFile>(){}[0]):
+    fun `<get-valueSingleFile>`(): kotlin.Int defined in com.example.klib.serialization.diagnostics
+    fun `<get-valueSingleFile>`(): kotlin.String defined in com.example.klib.serialization.diagnostics
+
+/main.kt:35:1: error: Platform declaration clash: The following properties have the same IR signature (com.example.klib.serialization.diagnostics/valueSingleFile|{}valueSingleFile[0]):
+    val valueSingleFile: kotlin.Int defined in com.example.klib.serialization.diagnostics
+    val valueSingleFile: kotlin.String defined in com.example.klib.serialization.diagnostics
+
+/main.kt:35:1: error: Platform declaration clash: The following functions have the same IR signature (com.example.klib.serialization.diagnostics/valueSingleFile.<get-valueSingleFile>|<get-valueSingleFile>(){}[0]):
+    fun `<get-valueSingleFile>`(): kotlin.Int defined in com.example.klib.serialization.diagnostics
+    fun `<get-valueSingleFile>`(): kotlin.String defined in com.example.klib.serialization.diagnostics
+
+/main.kt:37:1: error: Platform declaration clash: The following properties have the same IR signature (com.example.klib.serialization.diagnostics/myDelegated|{}myDelegated[0]):
+    val myDelegated: kotlin.Int defined in com.example.klib.serialization.diagnostics
+    val myDelegated: kotlin.Long defined in com.example.klib.serialization.diagnostics
+
+/main.kt:37:52: error: Platform declaration clash: The following functions have the same IR signature (com.example.klib.serialization.diagnostics/myDelegated.<get-myDelegated>|<get-myDelegated>(){}[0]):
+    fun `<get-myDelegated>`(): kotlin.Int defined in com.example.klib.serialization.diagnostics
+    fun `<get-myDelegated>`(): kotlin.Long defined in com.example.klib.serialization.diagnostics
+
+/main.kt:39:1: error: Platform declaration clash: The following properties have the same IR signature (com.example.klib.serialization.diagnostics/extensionValue|@kotlin.Int{}extensionValue[0]):
+    val kotlin.Int.extensionValue: kotlin.Int defined in com.example.klib.serialization.diagnostics
+    var kotlin.Int.extensionValue: kotlin.Int defined in com.example.klib.serialization.diagnostics
+
+/main.kt:41:1: error: Platform declaration clash: The following functions have the same IR signature (com.example.klib.serialization.diagnostics/extensionValue.<get-extensionValue>|<get-extensionValue>@kotlin.Int(){}[0]):
+    fun kotlin.Int.`<get-extensionValue>`(): kotlin.Int defined in com.example.klib.serialization.diagnostics
+    fun kotlin.Int.`<get-extensionValue>`(): kotlin.Int defined in com.example.klib.serialization.diagnostics
+
+/main.kt:44:5: error: Platform declaration clash: The following properties have the same IR signature (com.example.klib.serialization.diagnostics/Container.valueSameClass|{}valueSameClass[0]):
+    val valueSameClass: kotlin.Int defined in com.example.klib.serialization.diagnostics.Container
+    val valueSameClass: kotlin.Int defined in com.example.klib.serialization.diagnostics.Container
+
+/main.kt:44:5: error: Platform declaration clash: The following functions have the same IR signature (com.example.klib.serialization.diagnostics/Container.valueSameClass.<get-valueSameClass>|<get-valueSameClass>(){}[0]):
+    fun `<get-valueSameClass>`(): kotlin.Int defined in com.example.klib.serialization.diagnostics.Container
+    fun `<get-valueSameClass>`(): kotlin.Int defined in com.example.klib.serialization.diagnostics.Container
+
+/main.kt:45:5: error: Platform declaration clash: The following properties have the same IR signature (com.example.klib.serialization.diagnostics/Container.valueSameClass|{}valueSameClass[0]):
+    val valueSameClass: kotlin.Int defined in com.example.klib.serialization.diagnostics.Container
+    val valueSameClass: kotlin.Int defined in com.example.klib.serialization.diagnostics.Container
+
+/main.kt:45:5: error: Platform declaration clash: The following functions have the same IR signature (com.example.klib.serialization.diagnostics/Container.valueSameClass.<get-valueSameClass>|<get-valueSameClass>(){}[0]):
+    fun `<get-valueSameClass>`(): kotlin.Int defined in com.example.klib.serialization.diagnostics.Container
+    fun `<get-valueSameClass>`(): kotlin.Int defined in com.example.klib.serialization.diagnostics.Container
+
+/main.kt:48:9: error: Platform declaration clash: The following properties have the same IR signature (com.example.klib.serialization.diagnostics/Container.Companion.valueSameClassCompanion|{}valueSameClassCompanion[0]):
+    val valueSameClassCompanion: kotlin.Int defined in com.example.klib.serialization.diagnostics.Container.Companion
+    val valueSameClassCompanion: kotlin.Int defined in com.example.klib.serialization.diagnostics.Container.Companion
+
+/main.kt:48:9: error: Platform declaration clash: The following functions have the same IR signature (com.example.klib.serialization.diagnostics/Container.Companion.valueSameClassCompanion.<get-valueSameClassCompanion>|<get-valueSameClassCompanion>(){}[0]):
+    fun `<get-valueSameClassCompanion>`(): kotlin.Int defined in com.example.klib.serialization.diagnostics.Container.Companion
+    fun `<get-valueSameClassCompanion>`(): kotlin.Int defined in com.example.klib.serialization.diagnostics.Container.Companion
+
+/main.kt:49:9: error: Platform declaration clash: The following properties have the same IR signature (com.example.klib.serialization.diagnostics/Container.Companion.valueSameClassCompanion|{}valueSameClassCompanion[0]):
+    val valueSameClassCompanion: kotlin.Int defined in com.example.klib.serialization.diagnostics.Container.Companion
+    val valueSameClassCompanion: kotlin.Int defined in com.example.klib.serialization.diagnostics.Container.Companion
+
+/main.kt:49:9: error: Platform declaration clash: The following functions have the same IR signature (com.example.klib.serialization.diagnostics/Container.Companion.valueSameClassCompanion.<get-valueSameClassCompanion>|<get-valueSameClassCompanion>(){}[0]):
+    fun `<get-valueSameClassCompanion>`(): kotlin.Int defined in com.example.klib.serialization.diagnostics.Container.Companion
+    fun `<get-valueSameClassCompanion>`(): kotlin.Int defined in com.example.klib.serialization.diagnostics.Container.Companion
+
+/main.kt:52:5: error: Platform declaration clash: The following properties have the same IR signature (com.example.klib.serialization.diagnostics/Container.valueSameClassExtension|@kotlin.String{}valueSameClassExtension[0]):
+    val kotlin.String.valueSameClassExtension: kotlin.String defined in com.example.klib.serialization.diagnostics.Container
+    val kotlin.String.valueSameClassExtension: kotlin.String defined in com.example.klib.serialization.diagnostics.Container
+
+/main.kt:52:75: error: Platform declaration clash: The following functions have the same IR signature (com.example.klib.serialization.diagnostics/Container.valueSameClassExtension.<get-valueSameClassExtension>|<get-valueSameClassExtension>@kotlin.String(){}[0]):
+    fun kotlin.String.`<get-valueSameClassExtension>`(): kotlin.String defined in com.example.klib.serialization.diagnostics.Container
+    fun kotlin.String.`<get-valueSameClassExtension>`(): kotlin.String defined in com.example.klib.serialization.diagnostics.Container
+
+/main.kt:53:5: error: Platform declaration clash: The following properties have the same IR signature (com.example.klib.serialization.diagnostics/Container.valueSameClassExtension|@kotlin.String{}valueSameClassExtension[0]):
+    val kotlin.String.valueSameClassExtension: kotlin.String defined in com.example.klib.serialization.diagnostics.Container
+    val kotlin.String.valueSameClassExtension: kotlin.String defined in com.example.klib.serialization.diagnostics.Container
+
+/main.kt:53:75: error: Platform declaration clash: The following functions have the same IR signature (com.example.klib.serialization.diagnostics/Container.valueSameClassExtension.<get-valueSameClassExtension>|<get-valueSameClassExtension>@kotlin.String(){}[0]):
+    fun kotlin.String.`<get-valueSameClassExtension>`(): kotlin.String defined in com.example.klib.serialization.diagnostics.Container
+    fun kotlin.String.`<get-valueSameClassExtension>`(): kotlin.String defined in com.example.klib.serialization.diagnostics.Container
diff --git a/compiler/testData/diagnostics/klibSerializationTests/signatureClashVariables.kt b/compiler/testData/diagnostics/klibSerializationTests/signatureClashVariables.kt
new file mode 100644
index 00000000000..7b31f54715e
--- /dev/null
+++ b/compiler/testData/diagnostics/klibSerializationTests/signatureClashVariables.kt
@@ -0,0 +1,54 @@
+// WITH_STDLIB
+// DIAGNOSTICS: -ERROR_SUPPRESSION
+// FIR_IDENTICAL
+// RENDER_ALL_DIAGNOSTICS_FULL_TEXT
+
+// MODULE: lib
+package com.example.klib.serialization.diagnostics
+
+val valueSeparateModules: Int = 0
+
+// MODULE: main(lib)
+// FILE: foo.kt
+package com.example.klib.serialization.diagnostics
+
+val valueSeparateModules = 0
+private val privateValueSeparateFiles = 0
+
+<!CONFLICTING_KLIB_SIGNATURES_ERROR, CONFLICTING_KLIB_SIGNATURES_ERROR!>@Suppress("REDECLARATION") val valueSeparateFiles = 0<!>
+
+<!CONFLICTING_KLIB_SIGNATURES_ERROR!>@Suppress("REDECLARATION") val myDelegated: Long by <!CONFLICTING_KLIB_SIGNATURES_ERROR!>lazy { 0L }<!><!>
+
+<!CONFLICTING_KLIB_SIGNATURES_ERROR!>@Suppress("REDECLARATION")
+var Int.extensionValue: Int
+<!CONFLICTING_KLIB_SIGNATURES_ERROR!>get() = 0<!>
+set(value) = TODO()<!>
+
+// FILE: main.kt
+package com.example.klib.serialization.diagnostics
+
+private val privateValueSeparateFiles = 0
+
+<!CONFLICTING_KLIB_SIGNATURES_ERROR, CONFLICTING_KLIB_SIGNATURES_ERROR!>@Suppress("REDECLARATION") val valueSeparateFiles = 0<!>
+
+<!CONFLICTING_KLIB_SIGNATURES_ERROR, CONFLICTING_KLIB_SIGNATURES_ERROR!>@Suppress("REDECLARATION") val valueSingleFile: Int = 0<!>
+<!CONFLICTING_KLIB_SIGNATURES_ERROR, CONFLICTING_KLIB_SIGNATURES_ERROR!>@Suppress("REDECLARATION") val valueSingleFile: String = ""<!>
+
+<!CONFLICTING_KLIB_SIGNATURES_ERROR!>@Suppress("REDECLARATION") val myDelegated: Int by <!CONFLICTING_KLIB_SIGNATURES_ERROR!>lazy { 1 }<!><!>
+
+<!CONFLICTING_KLIB_SIGNATURES_ERROR!>@Suppress("REDECLARATION")
+val Int.extensionValue: Int
+<!CONFLICTING_KLIB_SIGNATURES_ERROR!>get() = 0<!><!>
+
+class Container {
+    <!CONFLICTING_KLIB_SIGNATURES_ERROR, CONFLICTING_KLIB_SIGNATURES_ERROR!>@Suppress("REDECLARATION") val valueSameClass = 0<!>
+    <!CONFLICTING_KLIB_SIGNATURES_ERROR, CONFLICTING_KLIB_SIGNATURES_ERROR!>@Suppress("REDECLARATION") val valueSameClass = 0<!>
+
+    companion object{
+        <!CONFLICTING_KLIB_SIGNATURES_ERROR, CONFLICTING_KLIB_SIGNATURES_ERROR!>@Suppress("REDECLARATION") val valueSameClassCompanion = 0<!>
+        <!CONFLICTING_KLIB_SIGNATURES_ERROR, CONFLICTING_KLIB_SIGNATURES_ERROR!>@Suppress("REDECLARATION") val valueSameClassCompanion = 0<!>
+    }
+
+    <!CONFLICTING_KLIB_SIGNATURES_ERROR!>@Suppress("REDECLARATION") val String.valueSameClassExtension: String <!CONFLICTING_KLIB_SIGNATURES_ERROR!>get() = ""<!><!>
+    <!CONFLICTING_KLIB_SIGNATURES_ERROR!>@Suppress("REDECLARATION") val String.valueSameClassExtension: String <!CONFLICTING_KLIB_SIGNATURES_ERROR!>get() = ""<!><!>
+}
\ No newline at end of file
diff --git a/js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/fir/FirPsiJsKlibDiagnosticsTestGenerated.java b/js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/fir/FirPsiJsKlibDiagnosticsTestGenerated.java
index 3454a486999..4f8b391f950 100644
--- a/js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/fir/FirPsiJsKlibDiagnosticsTestGenerated.java
+++ b/js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/fir/FirPsiJsKlibDiagnosticsTestGenerated.java
@@ -26,9 +26,21 @@ public class FirPsiJsKlibDiagnosticsTestGenerated extends AbstractFirPsiJsDiagno
   }
 
   @Test
-  @TestMetadata("signatureClash.kt")
-  public void testSignatureClash() {
-    runTest("compiler/testData/diagnostics/klibSerializationTests/signatureClash.kt");
+  @TestMetadata("signatureClashClasses.kt")
+  public void testSignatureClashClasses() {
+    runTest("compiler/testData/diagnostics/klibSerializationTests/signatureClashClasses.kt");
+  }
+
+  @Test
+  @TestMetadata("signatureClashFunctions.kt")
+  public void testSignatureClashFunctions() {
+    runTest("compiler/testData/diagnostics/klibSerializationTests/signatureClashFunctions.kt");
+  }
+
+  @Test
+  @TestMetadata("signatureClashVariables.kt")
+  public void testSignatureClashVariables() {
+    runTest("compiler/testData/diagnostics/klibSerializationTests/signatureClashVariables.kt");
   }
 
   @Test