[FIR] Let OptIn LV checker only run on last module in HMPP compilation

This fixes an issue where the opt-in annotation is defined in one of the
source sets of the compilation but opt-ins are defined for the whole
compilation which leads to false-positive "Opt-in requirement marker is
unresolved" in (e.g. common) source sets that don't have a dependency on
the module that contains the annotation.

#KT-60755 Fixed

compiler/cli/src/org/jetbrains/kotlin/cli/common/FirSessionConstructionUtils.kt

@@ -8,11 +8,14 @@ package org.jetbrains.kotlin.cli.common
 import org.jetbrains.kotlin.KtSourceFile
 import org.jetbrains.kotlin.analyzer.common.CommonPlatformAnalyzerServices
 import org.jetbrains.kotlin.config.*
-import org.jetbrains.kotlin.fir.*
+import org.jetbrains.kotlin.fir.DependencyListForCliModule
+import org.jetbrains.kotlin.fir.FirModuleData
+import org.jetbrains.kotlin.fir.FirModuleDataImpl
+import org.jetbrains.kotlin.fir.FirSession
+import org.jetbrains.kotlin.fir.analysis.checkers.OptInLanguageVersionSettingsCheckers
 import org.jetbrains.kotlin.fir.checkers.registerExtendedCommonCheckers
 import org.jetbrains.kotlin.fir.extensions.FirExtensionRegistrar
 import org.jetbrains.kotlin.fir.java.FirProjectSessionProvider
-import org.jetbrains.kotlin.fir.resolve.providers.impl.FirExtensionSyntheticFunctionInterfaceProvider
 import org.jetbrains.kotlin.fir.session.*
 import org.jetbrains.kotlin.fir.session.environment.AbstractProjectEnvironment
 import org.jetbrains.kotlin.fir.session.environment.AbstractProjectFileSearchScope
@@ -24,7 +27,6 @@ import org.jetbrains.kotlin.load.kotlin.PackageAndMetadataPartProvider
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.platform.CommonPlatforms
 import org.jetbrains.kotlin.platform.TargetPlatform
-import org.jetbrains.kotlin.platform.WasmPlatform
 import org.jetbrains.kotlin.platform.js.JsPlatforms
 import org.jetbrains.kotlin.platform.jvm.JvmPlatforms
 import org.jetbrains.kotlin.platform.konan.NativePlatforms
@@ -359,7 +361,10 @@ private inline fun <F> createSingleSession(
         analyzerServices
     )
 
-    val session = createFirSession(files, platformModuleData, sessionProvider, sessionConfigurator)
+    val session = createFirSession(files, platformModuleData, sessionProvider) {
+        sessionConfigurator()
+        useCheckers(OptInLanguageVersionSettingsCheckers)
+    }
     return SessionWithSources(session, files)
 }
 
@@ -399,7 +404,12 @@ private inline fun <F> createSessionsForLegacyMppProject(
     }
 
     val commonSession = createFirSession(commonFiles, commonModuleData, sessionProvider, sessionConfigurator)
-    val platformSession = createFirSession(platformFiles, platformModuleData, sessionProvider, sessionConfigurator)
+    val platformSession = createFirSession(platformFiles, platformModuleData, sessionProvider) {
+        sessionConfigurator()
+        // The CLI session might contain an opt-in for an annotation that's defined in the platform module.
+        // Therefore, only run the opt-in LV checker on the platform module.
+        useCheckers(OptInLanguageVersionSettingsCheckers)
+    }
 
     return listOf(
         SessionWithSources(commonSession, commonFiles),
@@ -436,10 +446,17 @@ private inline fun <F> createSessionsForHmppProject(
         moduleDataForHmppModule[module] = moduleData
     }
 
-    return hmppModuleStructure.modules.map { module ->
+    return hmppModuleStructure.modules.mapIndexed { i, module ->
         val moduleData = moduleDataForHmppModule.getValue(module)
         val sources = files.filter { fileBelongsToModule(it, module.name) }
-        val session = createFirSession(sources, moduleData, sessionProvider, sessionConfigurator)
+        val session = createFirSession(sources, moduleData, sessionProvider) {
+            sessionConfigurator()
+            // The CLI session might contain an opt-in for an annotation that's defined in one of the modules.
+            // The only module that's guaranteed to have a dependency on this module is the last one.
+            if (i == hmppModuleStructure.modules.lastIndex) {
+                useCheckers(OptInLanguageVersionSettingsCheckers)
+            }
+        }
         SessionWithSources(session, sources)
     }
 }

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/CommonLanguageVersionSettingsCheckers.kt

@@ -6,10 +6,9 @@
 package org.jetbrains.kotlin.fir.analysis.checkers
 
 import org.jetbrains.kotlin.fir.analysis.checkers.config.FirLanguageVersionSettingsChecker
-import org.jetbrains.kotlin.fir.analysis.checkers.config.FirOptInLanguageVersionSettingsChecker
 
 object CommonLanguageVersionSettingsCheckers : LanguageVersionSettingsCheckers() {
 
     override val languageVersionSettingsCheckers: Set<FirLanguageVersionSettingsChecker>
-        get() = setOf(FirOptInLanguageVersionSettingsChecker)
+        get() = setOf()
 }

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/OptInLanguageVersionSettingsCheckers.kt

@@ -0,0 +1,15 @@
+/*
+ * Copyright 2010-2023 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.fir.analysis.checkers
+
+import org.jetbrains.kotlin.fir.analysis.checkers.config.FirLanguageVersionSettingsChecker
+import org.jetbrains.kotlin.fir.analysis.checkers.config.FirOptInLanguageVersionSettingsChecker
+
+object OptInLanguageVersionSettingsCheckers : LanguageVersionSettingsCheckers() {
+
+    override val languageVersionSettingsCheckers: Set<FirLanguageVersionSettingsChecker>
+        get() = setOf(FirOptInLanguageVersionSettingsChecker)
+}

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/K2Tests.kt

@@ -137,4 +137,22 @@ class CustomK2Tests : KGPBaseTest() {
             }
         }
     }
+
+    @GradleTest
+    @DisplayName("All source sets have opt-in for annotation defined in platform source set. KT-60755")
+    fun kt60755OptInDefinedInPlatform(gradleVersion: GradleVersion) {
+        with(
+            project(
+                "k2-mpp-opt-in-in-platform",
+                gradleVersion,
+                buildOptions = defaultBuildOptions.copy(languageVersion = "2.0"),
+            )
+        ) {
+            val taskToExecute = ":compileKotlinJvm"
+            build(taskToExecute) {
+                assertTasksExecuted(taskToExecute)
+                assertOutputDoesNotContain("Opt-in requirement marker foo.bar.MyOptIn is unresolved")
+            }
+        }
+    }
 }

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/k2-mpp-opt-in-in-platform/build.gradle.kts

@@ -0,0 +1,22 @@
+import org.jetbrains.kotlin.gradle.dsl.KotlinVersion
+import org.jetbrains.kotlin.gradle.tasks.KotlinCompilationTask
+
+plugins {
+    kotlin("multiplatform")
+}
+
+repositories {
+	mavenLocal()
+    mavenCentral()
+}
+
+kotlin {
+    jvm()
+
+    sourceSets {
+        all {
+            languageSettings.optIn("foo.bar.MyOptIn")
+        }
+    }
+}
+

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/k2-mpp-opt-in-in-platform/gradle.properties

@@ -0,0 +1 @@
+kotlin.stdlib.default.dependency=false

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/k2-mpp-opt-in-in-platform/src/jvmMain/kotlin/MyOptIn.kt

@@ -0,0 +1,9 @@
+/*
+ * Copyright 2010-2023 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package foo.bar
+
+@RequiresOptIn(level = RequiresOptIn.Level.ERROR)
+annotation class MyOptIn