[FIR] Set metadata for IrFields generated from FirFields

This is useful for signature tests (see how
IrMangledNameAndSignatureDumpHandler uses `metadata` to retrieve
the original FIR declaration)

compiler/fir/fir2ir/jvm-backend/src/org/jetbrains/kotlin/fir/backend/jvm/FirMetadataSerializer.kt

@@ -5,6 +5,7 @@
 
 package org.jetbrains.kotlin.fir.backend.jvm
 
+import org.jetbrains.kotlin.KtFakeSourceElementKind
 import org.jetbrains.kotlin.backend.common.actualizer.IrActualizedResult
 import org.jetbrains.kotlin.backend.jvm.JvmBackendContext
 import org.jetbrains.kotlin.backend.jvm.JvmLoweredDeclarationOrigin
@@ -12,15 +13,12 @@ import org.jetbrains.kotlin.backend.jvm.metadata.MetadataSerializer
 import org.jetbrains.kotlin.codegen.ClassBuilderMode
 import org.jetbrains.kotlin.codegen.serialization.JvmSerializationBindings
 import org.jetbrains.kotlin.config.*
-import org.jetbrains.kotlin.fir.FirSession
+import org.jetbrains.kotlin.fir.*
 import org.jetbrains.kotlin.fir.backend.Fir2IrComponents
 import org.jetbrains.kotlin.fir.backend.FirMetadataSource
 import org.jetbrains.kotlin.fir.backend.extractFirDeclarations
-import org.jetbrains.kotlin.fir.containingClassForLocal
 import org.jetbrains.kotlin.fir.declarations.*
 import org.jetbrains.kotlin.fir.declarations.builder.*
-import org.jetbrains.kotlin.fir.languageVersionSettings
-import org.jetbrains.kotlin.fir.packageFqName
 import org.jetbrains.kotlin.fir.resolve.ScopeSession
 import org.jetbrains.kotlin.fir.resolve.toFirRegularClass
 import org.jetbrains.kotlin.fir.serialization.FirElementAwareStringTable
@@ -163,8 +161,20 @@ class FirMetadataSerializer(
     }
 
     override fun bindFieldMetadata(metadata: MetadataSource.Property, signature: Pair<Type, String>) {
-        val fir = (metadata as FirMetadataSource.Property).fir
-        globalSerializationBindings.put(FirJvmSerializerExtension.FIELD_FOR_PROPERTY, fir, signature)
+        when (metadata) {
+            is FirMetadataSource.Property -> globalSerializationBindings.put(
+                FirJvmSerializerExtension.FIELD_FOR_PROPERTY,
+                metadata.fir,
+                signature,
+            )
+            is FirMetadataSource.Field -> metadata.fir.run {
+                // We don't serialize synthetic delegate fields, and we don't expect any other fields here.
+                require(source?.kind == KtFakeSourceElementKind.ClassDelegationField) {
+                    "Expected delegate field, got ${render()} with source kind ${source?.kind}"
+                }
+            }
+            else -> error("Unexpected metadata: $metadata")
+        }
     }
 }
 

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/Fir2IrDeclarationStorage.kt

@@ -1115,7 +1115,9 @@ class Fir2IrDeclarationStorage(
             irParent = irClass,
             typeRef = initializer?.typeRef ?: field.returnTypeRef,
             origin = IrDeclarationOrigin.DELEGATE
-        )
+        ).apply {
+            metadata = FirMetadataSource.Field(field)
+        }
     }
 
     internal fun createIrField(
@@ -1160,6 +1162,7 @@ class Fir2IrDeclarationStorage(
                     isExternal = false
                 )
             }.apply {
+                metadata = FirMetadataSource.Field(field)
                 val staticFakeOverrideKey = getFieldStaticFakeOverrideKey(field, containingClassLookupTag)
                 if (staticFakeOverrideKey == null) {
                     fieldCache[field] = this

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/FirMetadataSource.kt

@@ -40,5 +40,10 @@ sealed class FirMetadataSource : MetadataSource {
         override val isConst: Boolean get() = fir.isConst
     }
 
+    class Field(override val fir: FirField) : FirMetadataSource(), MetadataSource.Property {
+        override val isConst: Boolean
+            get() = fir.isConst
+    }
+
     class Script(override val fir: FirScript) : FirMetadataSource(), MetadataSource.Script
 }

compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/mangle/ManglerChecker.kt

@@ -54,6 +54,9 @@ class ManglerChecker(
         override fun visitProperty(declaration: IrProperty, data: Nothing?): Boolean = true
         override fun visitClass(declaration: IrClass, data: Nothing?): Boolean =
             declaration.name == SpecialNames.NO_NAME_PROVIDED || super.visitClass(declaration, data)
+
+        override fun visitField(declaration: IrField, data: Nothing?): Boolean =
+            declaration.origin == IrDeclarationOrigin.DELEGATE || super.visitField(declaration, data)
     }
 
     private fun IrDeclaration.shouldBeSkipped(): Boolean = accept(skipper, null)