Support definitely non-nullable types (#2520)

* Support definitely non-nullable types

[Definitely non-nullable types](https://github.com/Kotlin/KEEP/blob/c72601cf35c1e95a541bb4b230edb474a6d1d1a8/proposals/definitely-non-nullable-types.md) are enabled since Kotlin 1.7

6 files changed, 49 insertions, 1 deletions

diff --git a/plugins/base/src/main/kotlin/signatures/KotlinSignatureProvider.kt b/plugins/base/src/main/kotlin/signatures/KotlinSignatureProvider.kt
index 294c1d24..02da3f24 100644
--- a/plugins/base/src/main/kotlin/signatures/KotlinSignatureProvider.kt
+++ b/plugins/base/src/main/kotlin/signatures/KotlinSignatureProvider.kt
@@ -430,6 +430,11 @@ class KotlinSignatureProvider(ctcc: CommentsToContentConverter, logger: DokkaLog
                 signatureForProjection(p.inner, showFullyQualifiedName)
                 operator("?")
             }
+            is DefinitelyNonNullable -> group(styles = emptySet()) {
+                signatureForProjection(p.inner, showFullyQualifiedName)
+                operator(" & ")
+                link("Any", DriOfAny)
+            }
 
             is TypeAliased -> signatureForProjection(p.typeAlias)
             is JavaObject -> {
diff --git a/plugins/base/src/main/kotlin/signatures/KotlinSignatureUtils.kt b/plugins/base/src/main/kotlin/signatures/KotlinSignatureUtils.kt
index 0fea9132..381fadf1 100644
--- a/plugins/base/src/main/kotlin/signatures/KotlinSignatureUtils.kt
+++ b/plugins/base/src/main/kotlin/signatures/KotlinSignatureUtils.kt
@@ -39,6 +39,7 @@ object KotlinSignatureUtils : JvmSignatureUtils {
                 is TypeParameter -> dri
                 is TypeConstructor -> dri
                 is Nullable -> inner.driOrNull
+                is DefinitelyNonNullable -> inner.driOrNull
                 is PrimitiveJavaType -> dri
                 is Void -> DriOfUnit
                 is JavaObject -> DriOfAny
@@ -52,6 +53,7 @@ object KotlinSignatureUtils : JvmSignatureUtils {
         is TypeParameter -> listOf(dri)
         is TypeConstructor -> listOf(dri) + projections.flatMap { it.drisOfAllNestedBounds }
         is Nullable -> inner.drisOfAllNestedBounds
+        is DefinitelyNonNullable -> inner.drisOfAllNestedBounds
         is PrimitiveJavaType -> listOf(dri)
         is Void -> listOf(DriOfUnit)
         is JavaObject -> listOf(DriOfAny)
diff --git a/plugins/base/src/main/kotlin/transformers/documentables/ExtensionExtractorTransformer.kt b/plugins/base/src/main/kotlin/transformers/documentables/ExtensionExtractorTransformer.kt
index 2a8baf0b..73023a86 100644
--- a/plugins/base/src/main/kotlin/transformers/documentables/ExtensionExtractorTransformer.kt
+++ b/plugins/base/src/main/kotlin/transformers/documentables/ExtensionExtractorTransformer.kt
@@ -9,7 +9,6 @@ import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.flow
 import kotlinx.coroutines.flow.flowOn
 import kotlinx.coroutines.flow.toList
-import org.jetbrains.dokka.base.signatures.KotlinSignatureUtils.driOrNull
 import org.jetbrains.dokka.links.DRI
 import org.jetbrains.dokka.links.DriOfAny
 import org.jetbrains.dokka.model.*
@@ -91,6 +90,7 @@ private fun Callable.asPairsWithReceiverDRIs(): Sequence<Pair<DRI, Callable>> =
 // care about it since there is nowhere to put documentation of given extension.
 private fun Callable.findReceiverDRIs(bound: Bound): Sequence<DRI> = when (bound) {
     is Nullable -> findReceiverDRIs(bound.inner)
+    is DefinitelyNonNullable -> findReceiverDRIs(bound.inner)
     is TypeParameter ->
         if (this is DFunction && bound.dri == this.dri)
             generics.find { it.name == bound.name }?.bounds?.asSequence()?.flatMap(::findReceiverDRIs).orEmpty()
diff --git a/plugins/base/src/main/kotlin/translators/descriptors/DefaultDescriptorToDocumentableTranslator.kt b/plugins/base/src/main/kotlin/translators/descriptors/DefaultDescriptorToDocumentableTranslator.kt
index 6c4d7a0d..bfd755cd 100644
--- a/plugins/base/src/main/kotlin/translators/descriptors/DefaultDescriptorToDocumentableTranslator.kt
+++ b/plugins/base/src/main/kotlin/translators/descriptors/DefaultDescriptorToDocumentableTranslator.kt
@@ -910,6 +910,9 @@ private class DokkaDescriptorVisitor(
                 expandedType.toBound(),
                 annotations()
             )
+            is DefinitelyNotNullType -> DefinitelyNonNullable(
+                original.toBound()
+            )
             else -> when (val ctor = constructor.declarationDescriptor) {
                 is TypeParameterDescriptor -> TypeParameter(
                     dri = DRI.from(ctor),
diff --git a/plugins/base/src/test/kotlin/signatures/SignatureTest.kt b/plugins/base/src/test/kotlin/signatures/SignatureTest.kt
index 2d17b7f8..75c199fa 100644
--- a/plugins/base/src/test/kotlin/signatures/SignatureTest.kt
+++ b/plugins/base/src/test/kotlin/signatures/SignatureTest.kt
@@ -2,8 +2,12 @@ package signatures
 
 import org.jetbrains.dokka.DokkaSourceSetID
 import org.jetbrains.dokka.base.testApi.testRunner.BaseAbstractTest
+import org.jetbrains.dokka.model.DFunction
+import org.jetbrains.dokka.model.DefinitelyNonNullable
+import org.jetbrains.dokka.model.dfs
 import org.junit.jupiter.api.Test
 import utils.*
+import kotlin.test.assertEquals
 import kotlin.test.assertFalse
 
 class SignatureTest : BaseAbstractTest() {
@@ -186,6 +190,39 @@ class SignatureTest : BaseAbstractTest() {
     }
 
     @Test
+    fun `fun with definitely non-nullable types`() {
+        val source = source("fun <T> elvisLike(x: T, y: T & Any): T & Any = x ?: y")
+        val writerPlugin = TestOutputWriterPlugin()
+
+        testInline(
+            source,
+            configuration,
+            pluginOverrides = listOf(writerPlugin)
+        ) {
+            documentablesTransformationStage = {
+                val fn = (it.dfs { it.name == "elvisLike" } as? DFunction).assertNotNull("Function elvisLike")
+
+                assert(fn.type is DefinitelyNonNullable)
+                assert(fn.parameters[1].type is DefinitelyNonNullable)
+            }
+            renderingStage = { _, _ ->
+                val signature = writerPlugin.writer.renderedContent("root/example/elvis-like.html")
+                assertEquals(2, signature.select("a[href=\"https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-any/index.html\"]").size)
+                signature.firstSignature().match(
+                    "fun <", A("T"), "> ", A("elvisLike"),
+                    "(",
+                    Span(
+                        Span("x: ", A("T"), ", "),
+                        Span("y: ", A("T"), " & ", A("Any"))
+                    ),
+                    "): ", A("T"), " & ", A("Any"), Span(),
+                    ignoreSpanWithTokenStyle = true
+                )
+            }
+        }
+    }
+
+    @Test
     fun `fun with keywords, params and generic bound`() {
         val source = source("inline suspend fun <T : String> simpleFun(a: Int, b: String): T = \"Celebrimbor\" as T")
         val writerPlugin = TestOutputWriterPlugin()
diff --git a/plugins/base/src/test/kotlin/utils/TestUtils.kt b/plugins/base/src/test/kotlin/utils/TestUtils.kt
index 99082110..e4bc4a1e 100644
--- a/plugins/base/src/test/kotlin/utils/TestUtils.kt
+++ b/plugins/base/src/test/kotlin/utils/TestUtils.kt
@@ -66,6 +66,7 @@ val DClass.supers
 val Bound.name: String?
     get() = when (this) {
         is Nullable -> inner.name
+        is DefinitelyNonNullable -> inner.name
         is TypeParameter -> name
         is PrimitiveJavaType -> name
         is TypeConstructor -> dri.classNames