Fix various warnings and cleanup samples

* Applied every IDE suggestion to the samples.
  We should keep the sample code copy-pasteable into the IDE
  without warnings.
* Gradle mentions that compileOnly dependencies don't work in Wasm,
  so changed the dependency of `kotlinx-datetime-zoneinfo`
  from compileOnly to api.
* Replaced the non-exhaustive-when error suppressions with
  a runtime check to be able to diagnose the issue better if
  we indeed make an error at some point.
  The runtime check can be removed if the compiler becomes smarter.
* Fixed various other warnings both in test/ and src/.

Author: dkhalanskyjb

buildSrc/src/main/kotlin/zoneInfosResourcesGenerator.kt

@@ -1,3 +1,4 @@
+import org.gradle.api.file.Directory
 import java.io.File
 
 /*
@@ -51,7 +52,7 @@ private fun loadTzBinaries(
     }
 }
 
-fun generateZoneInfosResources(zoneInfoDir: File, outputDir: File, version: String) {
+fun generateZoneInfosResources(zoneInfoDir: File, outputDir: Directory, version: String) {
     val header = buildString {
         appendLine()
         append("/* AUTOGENERATED FROM ZONE INFO DATABASE v.$version */")
@@ -70,7 +71,7 @@ fun generateZoneInfosResources(zoneInfoDir: File, outputDir: File, version: Stri
     loadedZones.forEachIndexed { id, tzData ->
         val tzDataName = "tzData$id"
         val data = generateByteArrayProperty(tzData, header, tzDataName)
-        File(outputDir, "$tzDataName.kt").writeText(data)
+        outputDir.file("$tzDataName.kt").asFile.writeText(data)
         tzData.fullTzNames.forEach { name ->
             zoneDataByNameBody.appendLine("    \"$name\" -> $tzDataName")
             getTimeZonesBody.appendLine("    \"$name\",")
@@ -97,5 +98,5 @@ fun generateZoneInfosResources(zoneInfoDir: File, outputDir: File, version: Stri
         append("}")
     }
 
-    File(outputDir, "tzData.kt").writeText(content)
+    outputDir.file("tzData.kt").asFile.writeText(content)
 }

core/build.gradle.kts

@@ -1,13 +1,13 @@
 import kotlinx.team.infra.mavenPublicationsPom
-import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
-import java.net.URL
-import javax.xml.parsers.DocumentBuilderFactory
-import java.io.ByteArrayOutputStream
-import java.io.PrintWriter
 import org.jetbrains.kotlin.gradle.ExperimentalKotlinGradlePluginApi
+import org.jetbrains.kotlin.gradle.ExperimentalWasmDsl
 import org.jetbrains.kotlin.gradle.dsl.JsModuleKind
-import org.jetbrains.kotlin.gradle.plugin.KotlinSourceSet
+import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
 import org.jetbrains.kotlin.konan.target.Family
+import java.io.ByteArrayOutputStream
+import java.io.PrintWriter
+import java.net.URL
+import javax.xml.parsers.DocumentBuilderFactory
 
 plugins {
     kotlin("multiplatform")
@@ -22,10 +22,6 @@ mavenPublicationsPom {
     description.set("Kotlin Datetime Library")
 }
 
-base {
-    archivesBaseName = "kotlinx-datetime" // doesn't work
-}
-
 val mainJavaToolchainVersion: String by project
 val modularJavaToolchainVersion: String by project
 val serializationVersion: String by project
@@ -112,6 +108,7 @@ kotlin {
         }
     }
 
+    @OptIn(ExperimentalWasmDsl::class)
     wasmJs {
         nodejs {
             testTask {
@@ -122,6 +119,7 @@ kotlin {
         }
     }
 
+    @OptIn(ExperimentalWasmDsl::class)
     wasmWasi {
         nodejs()
     }
@@ -295,7 +293,7 @@ tasks {
     // Workaround for https://youtrack.jetbrains.com/issue/KT-58303:
     // the `clean` task can't delete the expanded.lock file on Windows as it's still held by Gradle, failing the build
     val clean by existing(Delete::class) {
-        setDelete(fileTree(buildDir) {
+        setDelete(fileTree(layout.buildDirectory) {
             exclude("tmp/.cache/expanded/expanded.lock")
         })
     }
@@ -322,7 +320,7 @@ val downloadWindowsZonesMapping by tasks.registering {
     val output = "$projectDir/windows/src/internal/WindowsZoneNames.kt"
     outputs.file(output)
     doLast {
-        val initialFileContents = try { File(output).readBytes() } catch(e: Throwable) { ByteArray(0) }
+        val initialFileContents = try { File(output).readBytes() } catch(_: Throwable) { ByteArray(0) }
         val documentBuilderFactory = DocumentBuilderFactory.newInstance()
         // otherwise, parsing fails since it can't find the dtd
         documentBuilderFactory.setFeature("http://apache.org/xml/features/nonvalidating/load-external-dtd", false)

core/common/src/format/DateTimeComponents.kt

@@ -538,7 +538,7 @@ public class DateTimeComponents internal constructor(internal val contents: Date
         truncatedDate.year = requireParsedField(truncatedDate.year, "year") % 10_000
         val totalSeconds = try {
             val secDelta = safeMultiply((year!! / 10_000).toLong(), SECONDS_PER_10000_YEARS)
-            val epochDays = truncatedDate.toLocalDate().toEpochDays().toLong()
+            val epochDays = truncatedDate.toLocalDate().toEpochDays()
             safeAdd(secDelta, epochDays * SECONDS_PER_DAY + time.toSecondOfDay() - offset.totalSeconds)
         } catch (e: ArithmeticException) {
             throw DateTimeFormatException("The parsed date is outside the range representable by Instant", e)
@@ -654,10 +654,8 @@ internal class DateTimeComponentsFormat(override val actualFormat: CachedFormatS
         override fun timeZoneId() =
             actualBuilder.add(BasicFormatStructure(TimeZoneIdDirective()))
 
-        @Suppress("NO_ELSE_IN_WHEN")
-        override fun dateTimeComponents(format: DateTimeFormat<DateTimeComponents>) = when (format) {
-            is DateTimeComponentsFormat -> actualBuilder.add(format.actualFormat)
-        }
+        override fun dateTimeComponents(format: DateTimeFormat<DateTimeComponents>) =
+            format.withForceCast { format: DateTimeComponentsFormat -> actualBuilder.add(format.actualFormat) }
 
         override fun createEmpty(): Builder = Builder(AppendableFormatStructure())
     }

core/common/src/format/DateTimeFormat.kt

@@ -116,7 +116,7 @@ internal sealed class AbstractDateTimeFormat<T, U : Copyable<U>> : DateTimeForma
 
     open fun valueFromIntermediateOrNull(intermediate: U): T? = try {
         valueFromIntermediate(intermediate)
-    } catch (e: IllegalArgumentException) {
+    } catch (_: IllegalArgumentException) {
         null
     }
 

core/common/src/format/DateTimeFormatBuilder.kt

@@ -362,9 +362,8 @@ internal fun DateTimeFormatBuilder.WithTime.secondFractionInternal(
     maxLength: Int,
     grouping: List<Int>
 ) {
-    @Suppress("NO_ELSE_IN_WHEN")
-    when (this) {
-        is AbstractWithTimeBuilder -> addFormatStructureForTime(
+    withForceCast { value: AbstractWithTimeBuilder ->
+        value.addFormatStructureForTime(
             BasicFormatStructure(FractionalSecondDirective(minLength, maxLength, grouping))
         )
     }

core/common/src/format/LocalDateFormat.kt

@@ -280,10 +280,8 @@ internal interface AbstractWithDateBuilder : AbstractWithYearMonthBuilder, DateT
     override fun dayOfYear(padding: Padding) =
         addFormatStructureForDate(BasicFormatStructure(DayOfYearDirective(padding)))
 
-    @Suppress("NO_ELSE_IN_WHEN")
-    override fun date(format: DateTimeFormat<LocalDate>) = when (format) {
-        is LocalDateFormat -> addFormatStructureForDate(format.actualFormat)
-    }
+    override fun date(format: DateTimeFormat<LocalDate>) =
+        format.withForceCast { format: LocalDateFormat -> addFormatStructureForDate(format.actualFormat) }
 }
 
 // these are constants so that the formats are not recreated every time they are used

core/common/src/format/LocalDateTimeFormat.kt

@@ -8,6 +8,7 @@ package kotlinx.datetime.format
 import kotlinx.datetime.*
 import kotlinx.datetime.internal.format.*
 import kotlinx.datetime.internal.format.parser.Copyable
+import kotlinx.datetime.internal.withForceCast
 
 internal interface DateTimeFieldContainer : DateFieldContainer, TimeFieldContainer
 
@@ -67,10 +68,8 @@ internal interface AbstractWithDateTimeBuilder:
         addFormatStructureForDateTime(structure)
     }
 
-    @Suppress("NO_ELSE_IN_WHEN")
-    override fun dateTime(format: DateTimeFormat<LocalDateTime>) = when (format) {
-        is LocalDateTimeFormat -> addFormatStructureForDateTime(format.actualFormat)
-    }
+    override fun dateTime(format: DateTimeFormat<LocalDateTime>) =
+        format.withForceCast { format: LocalDateTimeFormat -> addFormatStructureForDateTime(format.actualFormat) }
 }
 
 // these are constants so that the formats are not recreated every time they are used

core/common/src/format/LocalTimeFormat.kt

@@ -10,6 +10,7 @@ import kotlinx.datetime.DateTimeFormatException
 import kotlinx.datetime.internal.DecimalFraction
 import kotlinx.datetime.internal.format.*
 import kotlinx.datetime.internal.format.parser.Copyable
+import kotlinx.datetime.internal.withForceCast
 
 /**
  * The AM/PM marker that indicates whether the hour in range `1..12` is before or after noon.
@@ -122,10 +123,8 @@ internal interface AbstractWithTimeBuilder : DateTimeFormatBuilder.WithTime {
     override fun secondFraction(minLength: Int, maxLength: Int) =
         addFormatStructureForTime(BasicFormatStructure(FractionalSecondDirective(minLength, maxLength)))
 
-    @Suppress("NO_ELSE_IN_WHEN")
-    override fun time(format: DateTimeFormat<LocalTime>) = when (format) {
-        is LocalTimeFormat -> addFormatStructureForTime(format.actualFormat)
-    }
+    override fun time(format: DateTimeFormat<LocalTime>) =
+        format.withForceCast { format: LocalTimeFormat -> addFormatStructureForTime(format.actualFormat) }
 }
 
 private class HourDirective(private val padding: Padding) :

core/common/src/format/Unicode.kt

@@ -5,8 +5,6 @@
 
 package kotlinx.datetime.format
 
-import kotlin.native.concurrent.*
-
 /**
  * Marks declarations in the datetime library that use format strings to define datetime formats.
  *
@@ -241,8 +239,7 @@ internal sealed interface UnicodeFormat {
     data class StringLiteral(val literal: String) : UnicodeFormat {
         override fun toString(): String = if (literal == "'") "''" else
             if (literal.any { it.isLetter() }) "'$literal'"
-            else if (literal.isEmpty()) ""
-            else literal
+            else literal.ifEmpty { "" }
     }
 
     sealed class Directive : UnicodeFormat {
@@ -257,8 +254,8 @@ internal sealed interface UnicodeFormat {
         sealed class YearMonthBased : DateBased() {
             abstract fun addToFormat(builder: DateTimeFormatBuilder.WithYearMonth)
             override fun addToFormat(builder: DateTimeFormatBuilder.WithDate) {
-                val downcastedBuilder: DateTimeFormatBuilder.WithYearMonth = builder
-                addToFormat(downcastedBuilder)
+                val downcastBuilder: DateTimeFormatBuilder.WithYearMonth = builder
+                addToFormat(downcastBuilder)
             }
 
             class Era(override val formatLength: Int) : YearMonthBased() {

core/common/src/format/UtcOffsetFormat.kt

@@ -8,6 +8,7 @@ package kotlinx.datetime.format
 import kotlinx.datetime.*
 import kotlinx.datetime.internal.format.*
 import kotlinx.datetime.internal.format.parser.Copyable
+import kotlinx.datetime.internal.withForceCast
 import kotlin.math.*
 
 internal interface UtcOffsetFieldContainer {
@@ -34,10 +35,8 @@ internal interface AbstractWithOffsetBuilder : DateTimeFormatBuilder.WithUtcOffs
     override fun offsetSecondsOfMinute(padding: Padding) =
         addFormatStructureForOffset(BasicFormatStructure(UtcOffsetSecondOfMinuteDirective(padding)))
 
-    @Suppress("NO_ELSE_IN_WHEN")
-    override fun offset(format: DateTimeFormat<UtcOffset>) = when (format) {
-        is UtcOffsetFormat -> addFormatStructureForOffset(format.actualFormat)
-    }
+    override fun offset(format: DateTimeFormat<UtcOffset>) =
+        format.withForceCast { format: UtcOffsetFormat -> addFormatStructureForOffset(format.actualFormat) }
 }
 
 internal class UtcOffsetFormat(override val actualFormat: CachedFormatStructure<UtcOffsetFieldContainer>) :