Add debug strings to frontend scopes-related structures

Such as:
- PackageFragmentProviders, and, in particular,
CompositePackageFragmentProviders
- JavaPackageFragments
- Scopes produced by those providers

The rationale is that a lot of frontend-facing bugs (like red code) are
easily recognizeable in resolution. But at that point you just see a
bunch of scopes, without meaningful toStrings, you don't know who has
produced them, and what's exactly wrong.

With this commit it should make debugging slightly easier: now at least
you'll be able to see that "this scope is a scope of package fragment
for foo.bar of module baz" and decide whether the declaration should or
should not have been resolved from such scope.

core/descriptors.jvm/src/org/jetbrains/kotlin/load/java/lazy/LazyJavaPackageFragmentProvider.kt

@@ -52,4 +52,6 @@ class LazyJavaPackageFragmentProvider(
 
     override fun getSubPackagesOf(fqName: FqName, nameFilter: (Name) -> Boolean) =
         getPackageFragment(fqName)?.getSubPackageFqNames().orEmpty()
+
+    override fun toString(): String = "LazyJavaPackageFragmentProvider of module ${c.components.module}"
 }

core/descriptors.jvm/src/org/jetbrains/kotlin/load/java/lazy/descriptors/JvmPackageScope.kt

@@ -103,4 +103,6 @@ class JvmPackageScope(
     override fun recordLookup(name: Name, location: LookupLocation) {
         c.components.lookupTracker.record(location, packageFragment, name)
     }
+
+    override fun toString(): String = "scope for $packageFragment"
 }

core/descriptors.jvm/src/org/jetbrains/kotlin/load/java/lazy/descriptors/LazyJavaPackageFragment.kt

@@ -35,7 +35,7 @@ import org.jetbrains.kotlin.storage.getValue
 
 class LazyJavaPackageFragment(
     outerContext: LazyJavaResolverContext,
-    private val jPackage: JavaPackage
+    private val jPackage: JavaPackage,
 ) : PackageFragmentDescriptorImpl(outerContext.module, jPackage.fqName) {
     private val c = outerContext.childForClassOrPackage(this)
 
@@ -86,7 +86,7 @@ class LazyJavaPackageFragment(
 
     override fun getMemberScope() = scope
 
-    override fun toString() = "Lazy Java package fragment: $fqName"
+    override fun toString() = "Lazy Java package fragment: $fqName of module ${c.components.module}"
 
     override fun getSource(): SourceElement = KotlinJvmBinaryPackageSourceElement(this)
 }

core/descriptors.jvm/src/org/jetbrains/kotlin/load/kotlin/DeserializedDescriptorResolver.kt

@@ -70,7 +70,8 @@ class DeserializedDescriptorResolver {
             kotlinClass.abiStability
         )
         return DeserializedPackageMemberScope(
-            descriptor, packageProto, nameResolver, kotlinClass.classHeader.metadataVersion, source, components
+            descriptor, packageProto, nameResolver, kotlinClass.classHeader.metadataVersion, source, components,
+            "scope for $source in $descriptor"
         ) {
             // All classes are included into Java scope
             emptyList()

core/descriptors.runtime/src/org/jetbrains/kotlin/descriptors/runtime/components/RuntimeModuleData.kt

@@ -92,7 +92,12 @@ class RuntimeModuleData private constructor(
             )
 
             module.setDependencies(module)
-            module.initialize(CompositePackageFragmentProvider(listOf(javaDescriptorResolver.packageFragmentProvider, builtinsProvider)))
+            module.initialize(
+                CompositePackageFragmentProvider(
+                    listOf(javaDescriptorResolver.packageFragmentProvider, builtinsProvider),
+                    "CompositeProvider@RuntimeModuleData for $module"
+                )
+            )
 
             return RuntimeModuleData(
                 deserializationComponentsForJava.components,

core/descriptors/src/org/jetbrains/kotlin/descriptors/impl/CompositePackageFragmentProvider.kt

@@ -22,7 +22,8 @@ import java.util.*
 import org.jetbrains.kotlin.name.Name
 
 class CompositePackageFragmentProvider(// can be modified from outside
-    private val providers: List<PackageFragmentProvider>
+    private val providers: List<PackageFragmentProvider>,
+    private val debugName: String
 ) : PackageFragmentProviderOptimized {
 
     init {
@@ -55,4 +56,6 @@ class CompositePackageFragmentProvider(// can be modified from outside
         }
         return result
     }
+
+    override fun toString(): String = debugName
 }

core/descriptors/src/org/jetbrains/kotlin/descriptors/impl/ModuleDescriptorImpl.kt

@@ -101,9 +101,12 @@ class ModuleDescriptorImpl @JvmOverloads constructor(
                 "Dependency module ${dependency.id} was not initialized by the time contents of dependent module ${this.id} were queried"
             }
         }
-        CompositePackageFragmentProvider(dependenciesDescriptors.map {
-            it.packageFragmentProviderForModuleContent!!
-        })
+        CompositePackageFragmentProvider(
+            dependenciesDescriptors.map {
+                it.packageFragmentProviderForModuleContent!!
+            },
+            "CompositeProvider@ModuleDescriptor for $name"
+        )
     }
 
     private val isInitialized: Boolean

core/descriptors/src/org/jetbrains/kotlin/descriptors/impl/PackageFragmentDescriptorImpl.kt

@@ -22,12 +22,16 @@ import org.jetbrains.kotlin.descriptors.PackageFragmentDescriptor
 import org.jetbrains.kotlin.descriptors.SourceElement
 import org.jetbrains.kotlin.descriptors.annotations.Annotations
 import org.jetbrains.kotlin.name.FqName
+import org.jetbrains.kotlin.resolve.descriptorUtil.module
 
 abstract class PackageFragmentDescriptorImpl(
         module: ModuleDescriptor,
         final override val fqName: FqName
 ) : DeclarationDescriptorNonRootImpl(module, Annotations.EMPTY, fqName.shortNameOrSpecial(), SourceElement.NO_SOURCE),
         PackageFragmentDescriptor {
+    // Not inlined in order to not capture ref on 'module'
+    private val debugString: String = "package $fqName of $module"
+
     override fun <R, D> accept(visitor: DeclarationDescriptorVisitor<R, D>, data: D): R =
             visitor.visitPackageFragmentDescriptor(this, data)
 
@@ -39,5 +43,5 @@ abstract class PackageFragmentDescriptorImpl(
         return SourceElement.NO_SOURCE
     }
 
-    override fun toString(): String = "package $fqName"
+    override fun toString(): String = debugString
 }

core/descriptors/src/org/jetbrains/kotlin/descriptors/impl/SubpackagesScope.kt

@@ -66,4 +66,6 @@ open class SubpackagesScope(private val moduleDescriptor: ModuleDescriptor, priv
         p.popIndent()
         p.println("}")
     }
+
+    override fun toString(): String = "subpackages of $fqName from $moduleDescriptor"
 }

core/deserialization/src/org/jetbrains/kotlin/serialization/deserialization/DeserializedPackageFragmentImpl.kt

@@ -49,12 +49,13 @@ abstract class DeserializedPackageFragmentImpl(
         _proto = null
         _memberScope = DeserializedPackageMemberScope(
             this, proto.`package`, nameResolver, metadataVersion, containerSource, components,
-            classNames = {
-                classDataFinder.allClassIds.filter { classId ->
-                    !classId.isNestedClass && classId !in ClassDeserializer.BLACK_LIST
-                }.map { it.shortClassName }
-            }
-        )
+            "scope of $this"
+        ) {
+            classDataFinder.allClassIds.filter { classId ->
+                !classId.isNestedClass && classId !in ClassDeserializer.BLACK_LIST
+            }.map { it.shortClassName }
+        }
+
     }
 
     override fun getMemberScope(): MemberScope = _memberScope

core/deserialization/src/org/jetbrains/kotlin/serialization/deserialization/MetadataPackageFragmentProvider.kt

@@ -110,10 +110,18 @@ class MetadataPackageFragment(
             val stream = finder.findMetadata(ClassId(fqName, Name.identifier(partName))) ?: continue
             val (proto, nameResolver, version) = readProto(stream)
 
-            scopes.add(DeserializedPackageMemberScope(
-                this, proto.`package`, nameResolver, version, containerSource = null, components = components,
-                classNames = { emptyList() }
-            ))
+            scopes.add(
+                DeserializedPackageMemberScope(
+                    this,
+                    proto.`package`,
+                    nameResolver,
+                    version,
+                    containerSource = null,
+                    components = components,
+                    debugName = "scope with top-level callables and type aliases (no classes) for package part $partName of $this",
+                    classNames = { emptyList() },
+                )
+            )
         }
 
         // Also add the deserialized scope that can load all classes from this package
@@ -121,7 +129,9 @@ class MetadataPackageFragment(
             this, ProtoBuf.Package.getDefaultInstance(),
             NameResolverImpl(ProtoBuf.StringTable.getDefaultInstance(), ProtoBuf.QualifiedNameTable.getDefaultInstance()),
             BuiltInsBinaryVersion.INSTANCE, // Exact version does not matter here
-            containerSource = null, components = components, classNames = { emptyList() }
+            containerSource = null, components = components,
+            debugName = "scope for all classes of $this",
+            classNames = { emptyList() },
         ) {
             override fun hasClass(name: Name): Boolean = hasTopLevelClass(name)
             override fun definitelyDoesNotContainName(name: Name) = false
@@ -129,7 +139,7 @@ class MetadataPackageFragment(
             override fun getNonDeclaredClassifierNames(): Set<Name>? = null
         })
 
-        return ChainedMemberScope.create("Metadata scope", scopes)
+        return ChainedMemberScope.create(".kotlin_metadata parts scope of $this", scopes)
     }
 
     override fun getMemberScope() = memberScope()

core/deserialization/src/org/jetbrains/kotlin/serialization/deserialization/builtins/BuiltInsPackageFragmentImpl.kt

@@ -10,6 +10,7 @@ import org.jetbrains.kotlin.descriptors.ModuleDescriptor
 import org.jetbrains.kotlin.metadata.ProtoBuf
 import org.jetbrains.kotlin.metadata.builtins.BuiltInsBinaryVersion
 import org.jetbrains.kotlin.name.FqName
+import org.jetbrains.kotlin.resolve.descriptorUtil.module
 import org.jetbrains.kotlin.serialization.deserialization.DeserializedPackageFragmentImpl
 import org.jetbrains.kotlin.storage.StorageManager
 import java.io.InputStream
@@ -52,4 +53,6 @@ class BuiltInsPackageFragmentImpl private constructor(
             return BuiltInsPackageFragmentImpl(fqName, storageManager, module, proto, version, isFallback)
         }
     }
+
+    override fun toString(): String = "builtins package fragment for $fqName from $module"
 }

core/deserialization/src/org/jetbrains/kotlin/serialization/deserialization/descriptors/DeserializedPackageMemberScope.kt

@@ -39,7 +39,8 @@ open class DeserializedPackageMemberScope(
     metadataVersion: BinaryVersion,
     containerSource: DeserializedContainerSource?,
     components: DeserializationComponents,
-    classNames: () -> Collection<Name>
+    private val debugName: String,
+    classNames: () -> Collection<Name>,
 ) : DeserializedMemberScope(
     components.createContext(
         packageDescriptor, nameResolver, TypeTable(proto.typeTable),
@@ -74,4 +75,6 @@ open class DeserializedPackageMemberScope(
     override fun addEnumEntryDescriptors(result: MutableCollection<DeclarationDescriptor>, nameFilter: (Name) -> Boolean) {
         // Do nothing
     }
+
+    override fun toString(): String = debugName
 }