Fix warnings in compiler code and tests

compiler/tests-common/tests/org/jetbrains/kotlin/codegen/debugInformation/AbstractLocalVariableTest.kt

@@ -118,7 +118,9 @@ abstract class AbstractLocalVariableTest : AbstractDebugTest() {
             }
         }
 
+        @Suppress("UNCHECKED_CAST")
         val compressedLog = compressRunsWithoutLinenumber(loggedItems as List<LVTStep>, LVTStep::location)
+
         val actualLocalVariables = compressedLog.joinToString("\n") {
             "// ${it.location.formatAsExpectation()}: ${it.visibleVars.joinToString(", ")}".trim()
         }

compiler/tests-common/tests/org/jetbrains/kotlin/codegen/debugInformation/AbstractSteppingTest.kt

@@ -56,6 +56,7 @@ abstract class AbstractSteppingTest : AbstractDebugTest() {
         val lines = wholeFile.readLines()
         val forceStepInto = lines.any { it.startsWith(FORCE_STEP_INTO_MARKER) }
 
+        @Suppress("UNCHECKED_CAST")
         val actualLineNumbers = compressRunsWithoutLinenumber(loggedItems as List<LocatableEvent>, LocatableEvent::location)
             .filter {
                 val location = it.location()
@@ -98,4 +99,3 @@ abstract class AbstractSteppingTest : AbstractDebugTest() {
         assertEqualsToFile(wholeFile, actual.joinToString("\n"))
     }
 }
-

compiler/tests-common/tests/org/jetbrains/kotlin/fir/VMCounters.kt

@@ -3,13 +3,13 @@
  * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
  */
 @file:Suppress("JAVA_MODULE_DOES_NOT_EXPORT_PACKAGE")
+
 package org.jetbrains.kotlin.fir
 
 import org.jetbrains.kotlin.daemon.common.threadCpuTime
 import org.jetbrains.kotlin.daemon.common.threadUserTime
 import sun.management.ManagementFactoryHelper
 
-
 data class GCInfo(val name: String, val gcTime: Long, val collections: Long) {
     operator fun minus(other: GCInfo): GCInfo {
         return this.copy(
@@ -36,6 +36,7 @@ data class VMCounters(val userTime: Long, val cpuTime: Long, val gcInfo: Map<Str
 private fun <K, V> merge(first: Map<K, V>, second: Map<K, V>, valueOp: (V, V) -> V): Map<K, V> {
     val result = first.toMutableMap()
     for ((k, v) in second) {
+        @Suppress("NULLABLE_TYPE_PARAMETER_AGAINST_NOT_NULL_TYPE_PARAMETER") // KT-43225
         result.merge(k, v, valueOp)
     }
     return result
@@ -55,4 +56,4 @@ fun vmStateSnapshot(): VMCounters {
         threadMXBean.threadUserTime(), threadMXBean.threadCpuTime(),
         ManagementFactoryHelper.getGarbageCollectorMXBeans().associate { it.name to GCInfo(it.name, it.collectionTime, it.collectionCount) }
     )
-}
+}