Refactoring: collect all logic regarding detecting sourceSet platform in one function

Note that previously addSourceSetsToCompilation had logic regarding
platforms. The reason for that is that it was the last place where
default soruce sets of compilations could be distinguished from all
participated source sets.

So, to move that logic, we have to preserve default source sets.
Therefore, this commit introduces 'KotlinCompilation.defaultSourceSets',
and 'ImportingContext.isDefaultSourceSet' method.

The rest is trivial code moving/methods introduction

The resulting code isn't really pretty and likely has non-orthogonal
predicates, this will be cleaned-up in the next commits

idea/kotlin-gradle-tooling/src/KotlinMPPGradleModel.kt

@@ -98,7 +98,22 @@ interface KotlinNativeCompilationExtensions : Serializable {
 }
 
 interface KotlinCompilation : KotlinModule {
+    /**
+     * All source sets participated in this compilation, including those available
+     * via dependsOn.
+     */
     val sourceSets: Collection<KotlinSourceSet>
+
+    /**
+     * Only default source sets of this compilation, i.e. those which are included
+     * into compilations directly.
+     *
+     * Usually, those are automatically created source sets for automatically created
+     * compilations (like jvmMain for JVM compilations) or manually included source sets
+     * (like 'jvm().compilations["main"].source(mySourceSet)' )
+     */
+    val defaultSourceSets: Collection<KotlinSourceSet>
+
     val output: KotlinCompilationOutput
     val arguments: KotlinCompilationArguments
     val dependencyClasspath: Array<String>

idea/kotlin-gradle-tooling/src/KotlinMPPGradleModelBuilder.kt

@@ -363,16 +363,10 @@ class KotlinMPPGradleModelBuilder : ModelBuilderService {
     ): KotlinCompilationImpl {
         val dependsOnSourceSets = this.sourceSets.flatMap { it.dependsOnSourceSets }.mapNotNull { importingContext.sourceSetByName(it) }
 
-        if (!importingContext.getProperty(IS_HMPP_ENABLED)) {
-            // intermediate source sets should be common if HMPP is disabled
-            dependsOnSourceSets.subtract(this.sourceSets).forEach {
-                it.actualPlatforms.addSimplePlatforms(listOf(KotlinPlatform.COMMON))
-            }
-        }
-
         return KotlinCompilationImpl(
             this.name,
             this.sourceSets.union(dependsOnSourceSets),
+            this.sourceSets,
             this.dependencies,
             this.output,
             this.arguments,
@@ -520,6 +514,7 @@ class KotlinMPPGradleModelBuilder : ModelBuilderService {
 
         return KotlinCompilationImpl(
             gradleCompilation.name,
+            kotlinSourceSets, // In fact, it's only default source-sets. It will be corrected later, see [addDependsOnSourceSetsToCompilation]
             kotlinSourceSets,
             dependencies.map { dependencyMapper.getId(it) }.distinct().toTypedArray(),
             output,
@@ -740,14 +735,25 @@ class KotlinMPPGradleModelBuilder : ModelBuilderService {
 
             sourceSet.isTestModule = importingContext.compilationsBySourceSet(sourceSet)?.all { it.isTestModule } ?: false
 
-            importingContext.compilationsBySourceSet(sourceSet)?.let { compilations ->
-                val platforms = compilations.map { it.platform }
-                sourceSet.actualPlatforms.addSimplePlatforms(platforms)
-            }
+            importingContext.computeSourceSetPlatforms(sourceSet)
+        }
+    }
 
-            if (importingContext.shouldCoerceToCommon(sourceSet)) {
-                sourceSet.actualPlatforms.addSimplePlatforms(listOf(KotlinPlatform.COMMON))
-            }
+    private fun MultiplatformModelImportingContext.computeSourceSetPlatforms(sourceSet: KotlinSourceSetImpl) {
+        if (shouldCoerceToCommon(sourceSet)) {
+            sourceSet.actualPlatforms.addSimplePlatforms(listOf(KotlinPlatform.COMMON))
+            return
+        }
+
+        if (!getProperty(IS_HMPP_ENABLED) && !isDefaultSourceSet(sourceSet)) {
+            // intermediate source sets should be common if HMPP is disabled
+            sourceSet.actualPlatforms.addSimplePlatforms(listOf(KotlinPlatform.COMMON))
+            return
+        }
+
+        compilationsBySourceSet(sourceSet)?.let { compilations ->
+            val platforms = compilations.map { it.platform }
+            sourceSet.actualPlatforms.addSimplePlatforms(platforms)
         }
     }
 

idea/kotlin-gradle-tooling/src/KotlinMPPGradleModelImpl.kt

@@ -128,6 +128,7 @@ data class KotlinNativeCompilationExtensionsImpl(
 data class KotlinCompilationImpl(
     override val name: String,
     override val sourceSets: Collection<KotlinSourceSet>,
+    override val defaultSourceSets: Collection<KotlinSourceSet>,
     override val dependencies: Array<KotlinDependencyId>,
     override val output: KotlinCompilationOutput,
     override val arguments: KotlinCompilationArguments,
@@ -139,11 +140,8 @@ data class KotlinCompilationImpl(
     // create deep copy
     constructor(kotlinCompilation: KotlinCompilation, cloningCache: MutableMap<Any, Any>) : this(
         kotlinCompilation.name,
-        kotlinCompilation.sourceSets.map { initialSourceSet ->
-            (cloningCache[initialSourceSet] as? KotlinSourceSet) ?: KotlinSourceSetImpl(initialSourceSet, cloningCache).also {
-                cloningCache[initialSourceSet] = it
-            }
-        }.toList(),
+        cloneSourceSetsWithCaching(kotlinCompilation.sourceSets, cloningCache),
+        cloneSourceSetsWithCaching(kotlinCompilation.defaultSourceSets, cloningCache),
         kotlinCompilation.dependencies,
         KotlinCompilationOutputImpl(kotlinCompilation.output),
         KotlinCompilationArgumentsImpl(kotlinCompilation.arguments),
@@ -166,6 +164,19 @@ data class KotlinCompilationImpl(
                 || platform == KotlinPlatform.ANDROID && name.contains("Test")
 
     override fun toString() = name
+
+    companion object {
+        private fun cloneSourceSetsWithCaching(
+            sourceSets: Collection<KotlinSourceSet>,
+            cloningCache: MutableMap<Any, Any>
+        ): List<KotlinSourceSet> =
+            sourceSets.map { initialSourceSet ->
+                (cloningCache[initialSourceSet] as? KotlinSourceSet) ?: KotlinSourceSetImpl(initialSourceSet, cloningCache).also {
+                    cloningCache[initialSourceSet] = it
+                }
+            }
+
+    }
 }
 
 data class KotlinTargetJarImpl(

idea/kotlin-gradle-tooling/src/MultiplatformModelImportingContext.kt

@@ -34,6 +34,14 @@ internal interface MultiplatformModelImportingContext {
      * it anywhere (essentially this is a misconfiguration)
      */
     fun isOrphanSourceSet(sourceSet: KotlinSourceSet): Boolean = compilationsBySourceSet(sourceSet) == null
+
+    /**
+     * "Default" source-set is a source-set which is included into compilation directly, rather
+     * through closure over dependsOn-relation.
+     *
+     * See also KDoc for [KotlinCompilation.defaultSourceSets]
+     */
+    fun isDefaultSourceSet(sourceSet: KotlinSourceSet): Boolean
 }
 
 internal fun MultiplatformModelImportingContext.getProperty(property: GradleImportProperties): Boolean = project.getProperty(property)
@@ -71,6 +79,7 @@ internal class MultiplatformModelImportingContextImpl(override val project: Proj
     override lateinit var compilations: Collection<KotlinCompilation>
         private set
     private lateinit var sourceSetToParticipatedCompilations: Map<KotlinSourceSet, Set<KotlinCompilation>>
+    private lateinit var allDefaultSourceSets: Set<KotlinSourceSet>
 
 
     /** see [initializeTargets] */
@@ -102,6 +111,8 @@ internal class MultiplatformModelImportingContextImpl(override val project: Proj
         }
 
         this.sourceSetToParticipatedCompilations = sourceSetToCompilations
+
+        this.allDefaultSourceSets = compilations.flatMapTo(mutableSetOf()) { it.defaultSourceSets }
     }
 
     internal fun initializeTargets(targets: Collection<KotlinTarget>) {
@@ -112,6 +123,8 @@ internal class MultiplatformModelImportingContextImpl(override val project: Proj
     // overload for small optimization
     override fun isOrphanSourceSet(sourceSet: KotlinSourceSet): Boolean = sourceSet !in sourceSetToParticipatedCompilations.keys
 
+    override fun isDefaultSourceSet(sourceSet: KotlinSourceSet): Boolean = sourceSet in allDefaultSourceSets
+
     override fun compilationsBySourceSet(sourceSet: KotlinSourceSet): Collection<KotlinCompilation>? =
         sourceSetToParticipatedCompilations[sourceSet]