[Plugin API] Add API to load top level declaration by its signature

- request from JP Compose, #KT-44100

compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/extensions/IrPluginContext.kt

@@ -10,7 +10,9 @@ import org.jetbrains.kotlin.config.LanguageVersionSettings
 import org.jetbrains.kotlin.descriptors.ModuleDescriptor
 import org.jetbrains.kotlin.ir.ObsoleteDescriptorBasedAPI
 import org.jetbrains.kotlin.ir.builders.IrGeneratorContext
+import org.jetbrains.kotlin.ir.linkage.IrDeserializer
 import org.jetbrains.kotlin.ir.symbols.*
+import org.jetbrains.kotlin.ir.util.IdSignature
 import org.jetbrains.kotlin.ir.util.IrMessageLogger
 import org.jetbrains.kotlin.ir.util.ReferenceSymbolTable
 import org.jetbrains.kotlin.ir.util.TypeTranslator
@@ -51,4 +53,7 @@ interface IrPluginContext : IrGeneratorContext {
     fun referenceConstructors(classFqn: FqName): Collection<IrConstructorSymbol>
     fun referenceFunctions(fqName: FqName): Collection<IrSimpleFunctionSymbol>
     fun referenceProperties(fqName: FqName): Collection<IrPropertySymbol>
+
+    // temporary solution to load synthetic top-level declaration
+    fun referenceTopLevel(signature: IdSignature, kind: IrDeserializer.TopLevelSymbolKind, moduleDescriptor: ModuleDescriptor): IrSymbol?
 }

compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/extensions/IrPluginContextImpl.kt

@@ -16,6 +16,7 @@ import org.jetbrains.kotlin.ir.declarations.IrConstructor
 import org.jetbrains.kotlin.ir.descriptors.IrBuiltIns
 import org.jetbrains.kotlin.ir.linkage.IrDeserializer
 import org.jetbrains.kotlin.ir.symbols.*
+import org.jetbrains.kotlin.ir.util.IdSignature
 import org.jetbrains.kotlin.ir.util.IrMessageLogger
 import org.jetbrains.kotlin.ir.util.ReferenceSymbolTable
 import org.jetbrains.kotlin.ir.util.TypeTranslator
@@ -134,4 +135,14 @@ open class IrPluginContextImpl constructor(
             descriptors.map { st.referenceProperty(it) }
         }
     }
+
+    override fun referenceTopLevel(
+        signature: IdSignature,
+        kind: IrDeserializer.TopLevelSymbolKind,
+        moduleDescriptor: ModuleDescriptor
+    ): IrSymbol? {
+        val symbol = linker.resolveBySignatureInModule(signature, kind, moduleDescriptor.name)
+        linker.postProcess()
+        return symbol
+    }
 }