Add option to merge implicit expect-actual declarations (#2316)

* Add option to merge implicit expect-actual declarations

* Merge entries, constructors

* Fix StdLib integration test

* Add doc

3 files changed, 39 insertions, 31 deletions

diff --git a/plugins/base/src/main/kotlin/transformers/pages/merger/SameMethodNamePageMergerStrategy.kt b/plugins/base/src/main/kotlin/transformers/pages/merger/SameMethodNamePageMergerStrategy.kt
index 2fb70fc8..6c12c719 100644
--- a/plugins/base/src/main/kotlin/transformers/pages/merger/SameMethodNamePageMergerStrategy.kt
+++ b/plugins/base/src/main/kotlin/transformers/pages/merger/SameMethodNamePageMergerStrategy.kt
@@ -23,7 +23,7 @@ class SameMethodNamePageMergerStrategy(val logger: DokkaLogger) : PageMergerStra
             children = members.flatMap { it.children }.distinct(),
             content = squashDivergentInstances(members).withSourceSets(members.allSourceSets()),
             embeddedResources = members.flatMap { it.embeddedResources }.distinct(),
-            documentable = null
+            documentables = members.flatMap { it.documentables }
         )
 
         return (pages - members) + listOf(merged)
@@ -37,9 +37,9 @@ class SameMethodNamePageMergerStrategy(val logger: DokkaLogger) : PageMergerStra
             .reduce { acc, node ->
                 acc.mapTransform<ContentDivergentGroup, ContentNode> { g ->
                     g.copy(children = (g.children +
-                            (node.dfs { it is ContentDivergentGroup && it.groupID == g.groupID } as? ContentDivergentGroup)
-                                ?.children?.single()
-                            ).filterNotNull()
+                            ((node.dfs { it is ContentDivergentGroup && it.groupID == g.groupID } as? ContentDivergentGroup)
+                                ?.children ?: emptyList())
+                            )
                     )
                 }
             }
diff --git a/plugins/base/src/main/kotlin/transformers/pages/samples/SamplesTransformer.kt b/plugins/base/src/main/kotlin/transformers/pages/samples/SamplesTransformer.kt
index 3ff7a77d..db133bb8 100644
--- a/plugins/base/src/main/kotlin/transformers/pages/samples/SamplesTransformer.kt
+++ b/plugins/base/src/main/kotlin/transformers/pages/samples/SamplesTransformer.kt
@@ -35,14 +35,18 @@ abstract class SamplesTransformer(val context: DokkaContext) : PageTransformer {
             "<script src=\"https://unpkg.com/kotlin-playground@1\"></script>"
 
         return input.transformContentPagesTree { page ->
-            page.documentable?.documentation?.entries?.fold(page) { acc, entry ->
-                entry.value.children.filterIsInstance<Sample>().fold(acc) { acc, sample ->
+            val samples = (page as? WithDocumentables)?.documentables?.flatMap {
+                it.documentation.entries.flatMap { entry ->
+                    entry.value.children.filterIsInstance<Sample>().map { entry.key to it }
+                }
+            }
+
+            samples?.fold(page as ContentPage) { acc, (sampleSourceSet, sample) ->
                     acc.modified(
-                        content = acc.content.addSample(page, entry.key, sample.name, analysis),
+                        content = acc.content.addSample(page, sampleSourceSet, sample.name, analysis),
                         embeddedResources = acc.embeddedResources + kotlinPlaygroundScript
                     )
-                }
-            } ?: page
+                } ?: page
         }
     }
 
diff --git a/plugins/base/src/main/kotlin/transformers/pages/sourcelinks/SourceLinksTransformer.kt b/plugins/base/src/main/kotlin/transformers/pages/sourcelinks/SourceLinksTransformer.kt
index f66ff222..93305055 100644
--- a/plugins/base/src/main/kotlin/transformers/pages/sourcelinks/SourceLinksTransformer.kt
+++ b/plugins/base/src/main/kotlin/transformers/pages/sourcelinks/SourceLinksTransformer.kt
@@ -1,15 +1,15 @@
 package org.jetbrains.dokka.base.transformers.pages.sourcelinks
 
-import com.intellij.psi.PsiElement
 import com.intellij.psi.PsiDocumentManager
+import com.intellij.psi.PsiElement
 import org.jetbrains.dokka.DokkaConfiguration
-import org.jetbrains.dokka.base.translators.documentables.PageContentBuilder
-import org.jetbrains.dokka.model.DocumentableSource
 import org.jetbrains.dokka.DokkaConfiguration.DokkaSourceSet
 import org.jetbrains.dokka.analysis.DescriptorDocumentableSource
 import org.jetbrains.dokka.analysis.PsiDocumentableSource
 import org.jetbrains.dokka.base.DokkaBase
 import org.jetbrains.dokka.base.resolvers.anchors.SymbolAnchorHint
+import org.jetbrains.dokka.base.translators.documentables.PageContentBuilder
+import org.jetbrains.dokka.model.DocumentableSource
 import org.jetbrains.dokka.model.WithSources
 import org.jetbrains.dokka.model.toDisplaySourceSets
 import org.jetbrains.dokka.pages.*
@@ -32,8 +32,9 @@ class SourceLinksTransformer(val context: DokkaContext) : PageTransformer {
 
     override fun invoke(input: RootPageNode) =
         input.transformContentPagesTree { node ->
-            when (val documentable = node.documentable) {
-                is WithSources -> resolveSources(documentable)
+            when (node) {
+                is WithDocumentables ->
+                    node.documentables.filterIsInstance<WithSources>().flatMap { resolveSources(it) }
                     .takeIf { it.isNotEmpty() }
                     ?.let { node.addSourcesContent(it) }
                     ?: node
@@ -65,23 +66,26 @@ class SourceLinksTransformer(val context: DokkaContext) : PageTransformer {
     private fun PageContentBuilder.buildSourcesContent(
         node: ContentPage,
         sources: List<Pair<DokkaSourceSet, String>>
-    ) = contentFor(
-        node.dri.first(),
-        node.documentable!!.sourceSets.toSet()
-    ) {
-        header(2, "Sources", kind = ContentKind.Source)
-        +ContentTable(
-            header = emptyList(),
-            children = sources.map {
-                buildGroup(node.dri, setOf(it.first), kind = ContentKind.Source, extra = mainExtra + SymbolAnchorHint(it.second, ContentKind.Source)) {
-                    link("${it.first.displayName} source", it.second)
-                }
-            },
-            dci = DCI(node.dri, ContentKind.Source),
-            sourceSets = node.documentable!!.sourceSets.toDisplaySourceSets(),
-            style = emptySet(),
-            extra = mainExtra + SimpleAttr.header("Sources")
-        )
+    ): ContentGroup {
+        val documentables = (node as? WithDocumentables)?.documentables.orEmpty()
+        return contentFor(
+            node.dri,
+            documentables.flatMap { it.sourceSets }.toSet()
+        ) {
+            header(2, "Sources", kind = ContentKind.Source)
+            +ContentTable(
+                header = emptyList(),
+                children = sources.map {
+                    buildGroup(node.dri, setOf(it.first), kind = ContentKind.Source, extra = mainExtra + SymbolAnchorHint(it.second, ContentKind.Source)) {
+                        link("${it.first.displayName} source", it.second)
+                    }
+                },
+                dci = DCI(node.dri, ContentKind.Source),
+                sourceSets = documentables.flatMap { it.sourceSets }.toDisplaySourceSets(),
+                style = emptySet(),
+                extra = mainExtra + SimpleAttr.header("Sources")
+            )
+        }
     }
 
     private fun DocumentableSource.toLink(sourceLink: SourceLink): String {