KT-64808 [stubs] Materialize all synthethic declarations in Kotlin Stubs

Here is the reasoning behind that change:

Historically, all the declarations generated by compiler plugins
were marked with `SYNTHESIZED` member kind in Kotlin Metadata
by K1 compiler.

In K1 IDE, descriptors were deserialized directly from the Kotlin
Metadata, and they saw all the generated declarations from it.

In the stubs, however, such declarations were not materialized at all.
It caused no troubles, since K1 IDE relied on descriptors to get the
essential resolution information in completion and other subsystems.
So, the resolution of members from jars processed
by compiler plugins (e.g. `kotlinx-serialization-json`) was mostly fine.

In K2 IDE, however, we use stubs to "deserialize" FIR declarations from
them, to later create `KtSymbol`s upon that FIR.

If we see a library file which was processed by compiler plugins, we
build stubs for it based on the Kotlin Metadata, and then use stubs to
create FIR.
But if stubs do not contain information about the generated
declarations,
then the resulting FIR will also not contain such declarations.

In the end, the K2 IDE would also be blind to such declarations, since
there is no other way to retrieve them from the library jar.

By meterializing all the synthethic declarations in stubs (with some
minor exceptions for data classes), we would avoid such problems,
and the resolve of such declarations from compiler jars in
K2 IDE would become possible.

Important note: currently, the Kotlin Metadata format between K1 and K2
frontends is not 100% the same; most notably, in K2, the generated
declarations are marked as regular declarations,
not as `SYNTHESIZED` ones.

Hence, if you compile a jar with the current version of K2 frontend,
then all the generated declarations would have a regular `DECLARATION`
origin, and there would be no such issues as described above.

There are two notes here:

1. K2 IDE still has to support the jars compiled by the K1 compiler,
so it still makes sense to alter the stubs and make the generated
declarations visible.
2. The issue about the different stub formats has been reported
(see KT-64924), and might be resolved in the future.
So it is possible that K2 frontend's metadata will also start
marking the generated declarations as `SYNTHESIZED`.

^KT-64808 Fixed

analysis/decompiled/decompiler-to-psi/src/org/jetbrains/kotlin/analysis/decompiler/psi/text/buildDecompiledText.kt

@@ -12,18 +12,14 @@ import org.jetbrains.kotlin.builtins.StandardNames
 import org.jetbrains.kotlin.contracts.description.ContractProviderKey
 import org.jetbrains.kotlin.descriptors.*
 import org.jetbrains.kotlin.name.FqName
-import org.jetbrains.kotlin.name.Name
-import org.jetbrains.kotlin.name.SpecialNames
 import org.jetbrains.kotlin.psi.psiUtil.quoteIfNeeded
 import org.jetbrains.kotlin.renderer.DescriptorRenderer
 import org.jetbrains.kotlin.renderer.DescriptorRendererModifier
 import org.jetbrains.kotlin.renderer.DescriptorRendererOptions
 import org.jetbrains.kotlin.renderer.render
-import org.jetbrains.kotlin.resolve.DataClassDescriptorResolver
 import org.jetbrains.kotlin.resolve.DescriptorUtils.isEnumEntry
 import org.jetbrains.kotlin.resolve.descriptorUtil.secondaryConstructors
 import org.jetbrains.kotlin.types.isFlexible
-import org.jetbrains.kotlin.util.OperatorNameConventions
 import org.jetbrains.kotlin.util.capitalizeDecapitalize.toLowerCaseAsciiOnly
 
 private const val DECOMPILED_CODE_COMMENT = "/* compiled code */"
@@ -44,18 +40,35 @@ fun DescriptorRendererOptions.defaultDecompilerRendererOptions() {
     propertyConstantRenderer = { _ -> COMPILED_DEFAULT_INITIALIZER }
 }
 
+/**
+ * @see org.jetbrains.kotlin.analysis.decompiler.stub.mustNotBeWrittenToStubs
+ */
 internal fun CallableMemberDescriptor.mustNotBeWrittenToDecompiledText(): Boolean {
     return when (kind) {
         CallableMemberDescriptor.Kind.DECLARATION, CallableMemberDescriptor.Kind.DELEGATION -> false
         CallableMemberDescriptor.Kind.FAKE_OVERRIDE -> true
-        CallableMemberDescriptor.Kind.SYNTHESIZED -> {
-            // Of all synthesized functions, only `component*` functions are rendered (for historical reasons)
-            !DataClassDescriptorResolver.isComponentLike(name) && name !in listOf(
-                OperatorNameConventions.EQUALS,
-                StandardNames.HASHCODE_NAME,
-                OperatorNameConventions.TO_STRING
+        CallableMemberDescriptor.Kind.SYNTHESIZED -> syntheticMemberMustNotBeWrittenToDecompiledText()
+    }
+}
+
+private fun CallableMemberDescriptor.syntheticMemberMustNotBeWrittenToDecompiledText(): Boolean {
+    val containingClass = containingDeclaration as? ClassDescriptor ?: return false
+
+    return when {
+        containingClass.isData && containingClass.kind != ClassKind.OBJECT -> {
+            // we want to materialize every synthetic data class function except for the 'copy' (for historical reasons)
+            name == StandardNames.DATA_CLASS_COPY
+        }
+
+        containingClass.kind == ClassKind.ENUM_CLASS -> {
+            name in arrayOf(
+                StandardNames.ENUM_VALUES,
+                StandardNames.ENUM_ENTRIES,
+                StandardNames.ENUM_VALUE_OF,
             )
         }
+
+        else -> false
     }
 }
 

analysis/decompiled/decompiler-to-stubs/src/org/jetbrains/kotlin/analysis/decompiler/stub/CallableClsStubBuilder.kt

@@ -26,12 +26,10 @@ import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.psi.stubs.KotlinPropertyStub
 import org.jetbrains.kotlin.psi.stubs.elements.KtStubElementTypes
 import org.jetbrains.kotlin.psi.stubs.impl.*
-import org.jetbrains.kotlin.resolve.DataClassResolver
 import org.jetbrains.kotlin.resolve.constants.ClassLiteralValue
 import org.jetbrains.kotlin.serialization.deserialization.AnnotatedCallableKind
 import org.jetbrains.kotlin.serialization.deserialization.ProtoContainer
 import org.jetbrains.kotlin.serialization.deserialization.getName
-import org.jetbrains.kotlin.util.OperatorNameConventions
 import org.jetbrains.kotlin.utils.addIfNotNull
 import org.jetbrains.kotlin.utils.addToStdlib.runIf
 
@@ -55,14 +53,14 @@ fun createDeclarationsStubs(
     propertyProtos: List<ProtoBuf.Property>,
 ) {
     for (propertyProto in propertyProtos) {
-        if (mustNotBeWrittenToStubs(propertyProto.flags, outerContext.nameResolver.getName(propertyProto.name))) {
+        if (mustNotBeWrittenToStubs(propertyProto.flags, outerContext.nameResolver.getName(propertyProto.name), protoContainer)) {
             continue
         }
 
         PropertyClsStubBuilder(parentStub, outerContext, protoContainer, propertyProto).build()
     }
     for (functionProto in functionProtos) {
-        if (mustNotBeWrittenToStubs(functionProto.flags, outerContext.nameResolver.getName(functionProto.name))) {
+        if (mustNotBeWrittenToStubs(functionProto.flags, outerContext.nameResolver.getName(functionProto.name), protoContainer)) {
             continue
         }
 
@@ -90,15 +88,27 @@ fun createConstructorStub(
     ConstructorClsStubBuilder(parentStub, outerContext, protoContainer, constructorProto).build()
 }
 
-private fun mustNotBeWrittenToStubs(flags: Int, name: Name): Boolean {
+/**
+ * @see org.jetbrains.kotlin.analysis.decompiler.psi.text.mustNotBeWrittenToDecompiledText
+ */
+private fun mustNotBeWrittenToStubs(flags: Int, name: Name, protoContainer: ProtoContainer): Boolean {
     return when (Flags.MEMBER_KIND.get(flags)) {
         MemberKind.FAKE_OVERRIDE -> true
         //TODO: fix decompiler to use sane criteria
-        MemberKind.SYNTHESIZED -> !DataClassResolver.isComponentLike(name) && name !in listOf(
-            OperatorNameConventions.EQUALS,
-            StandardNames.HASHCODE_NAME,
-            OperatorNameConventions.TO_STRING
-        )
+        MemberKind.SYNTHESIZED -> syntheticMemberMustNotBeWrittenToStubs(name, protoContainer)
+        else -> false
+    }
+}
+
+private fun syntheticMemberMustNotBeWrittenToStubs(name: Name, protoContainer: ProtoContainer): Boolean {
+    val containingClass = protoContainer as? ProtoContainer.Class ?: return false
+
+    return when {
+        containingClass.isData && containingClass.kind != ProtoBuf.Class.Kind.OBJECT -> {
+            // we want to materialize every synthetic data class function except for the 'copy' (for historical reasons)
+            name == StandardNames.DATA_CLASS_COPY
+        }
+
         else -> false
     }
 }