IR: make IrMetadataSourceOwner.metadata mutable

To avoid casting to specific Ir*Impl elements at call sites.

Also inherit from IrMetadataSourceOwner only where it's needed: class,
file, function, property. Previously this field was always null and took
some space for things like value parameters, type parameters, etc.

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/Fir2IrVisitor.kt

@@ -37,7 +37,6 @@ import org.jetbrains.kotlin.ir.IrStatement
 import org.jetbrains.kotlin.ir.UNDEFINED_OFFSET
 import org.jetbrains.kotlin.ir.builders.*
 import org.jetbrains.kotlin.ir.declarations.*
-import org.jetbrains.kotlin.ir.declarations.impl.IrFileImpl
 import org.jetbrains.kotlin.ir.expressions.*
 import org.jetbrains.kotlin.ir.expressions.impl.*
 import org.jetbrains.kotlin.ir.symbols.IrClassSymbol
@@ -94,7 +93,7 @@ class Fir2IrVisitor(
                 it.accept(this@Fir2IrVisitor, data) as? IrConstructorCall
             }
 
-            (this as IrFileImpl).metadata = FirMetadataSource.File(file, components.session)
+            metadata = FirMetadataSource.File(file, components.session)
         }
     }
 

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/lazy/AbstractFir2IrLazyDeclaration.kt

@@ -39,10 +39,6 @@ abstract class AbstractFir2IrLazyDeclaration<F : FirMemberDeclaration, D : IrSym
 
     lateinit var typeParameters: List<IrTypeParameter>
 
-    override var metadata: MetadataSource?
-        get() = null
-        set(_) = error("We should never need to store metadata of external declarations.")
-
     override lateinit var parent: IrDeclarationParent
 
     @ObsoleteDescriptorBasedAPI
@@ -54,4 +50,4 @@ abstract class AbstractFir2IrLazyDeclaration<F : FirMemberDeclaration, D : IrSym
             callGenerator.convertToIrConstructorCall(it) as? IrConstructorCall
         }
     }
-}
+}

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/lazy/Fir2IrLazyClass.kt

@@ -170,6 +170,10 @@ class Fir2IrLazyClass(
         result
     }
 
+    override var metadata: MetadataSource?
+        get() = null
+        set(_) = error("We should never need to store metadata of external declarations.")
+
     private fun FirNamedFunctionSymbol.isAbstractMethodOfAny(): Boolean {
         val fir = fir
         if (fir.modality != Modality.ABSTRACT) return false
@@ -194,4 +198,4 @@ class Fir2IrLazyClass(
         typeParameters = typeParameters.transformIfNeeded(transformer, data)
         declarations.transform { it.transform(transformer, data) }
     }
-}
+}

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/lazy/Fir2IrLazyConstructor.kt

@@ -13,10 +13,7 @@ import org.jetbrains.kotlin.fir.backend.toIrType
 import org.jetbrains.kotlin.fir.declarations.*
 import org.jetbrains.kotlin.fir.symbols.Fir2IrConstructorSymbol
 import org.jetbrains.kotlin.ir.ObsoleteDescriptorBasedAPI
-import org.jetbrains.kotlin.ir.declarations.IrClass
-import org.jetbrains.kotlin.ir.declarations.IrConstructor
-import org.jetbrains.kotlin.ir.declarations.IrDeclarationOrigin
-import org.jetbrains.kotlin.ir.declarations.IrValueParameter
+import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.declarations.lazy.lazyVar
 import org.jetbrains.kotlin.ir.expressions.IrBody
 import org.jetbrains.kotlin.ir.types.IrType
@@ -110,6 +107,10 @@ class Fir2IrLazyConstructor(
         }
     }
 
+    override var metadata: MetadataSource?
+        get() = null
+        set(_) = error("We should never need to store metadata of external declarations.")
+
     override fun <R, D> accept(visitor: IrElementVisitor<R, D>, data: D): R {
         return visitor.visitConstructor(this, data)
     }
@@ -133,4 +134,4 @@ class Fir2IrLazyConstructor(
 
         body = body?.transform(transformer, data)
     }
-}
+}

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/lazy/Fir2IrLazyProperty.kt

@@ -150,6 +150,10 @@ class Fir2IrLazyProperty(
         )
     }
 
+    override var metadata: MetadataSource?
+        get() = null
+        set(_) = error("We should never need to store metadata of external declarations.")
+
     override fun <R, D> accept(visitor: IrElementVisitor<R, D>, data: D): R {
         return visitor.visitProperty(this, data)
     }
@@ -165,4 +169,4 @@ class Fir2IrLazyProperty(
         getter = getter?.run { transform(transformer, data) as IrSimpleFunction }
         setter = setter?.run { transform(transformer, data) as IrSimpleFunction }
     }
-}
+}

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/lazy/Fir2IrLazySimpleFunction.kt

@@ -132,6 +132,10 @@ class Fir2IrLazySimpleFunction(
             ?.filterIsInstance<IrSimpleFunctionSymbol>().orEmpty()
     }
 
+    override var metadata: MetadataSource?
+        get() = null
+        set(_) = error("We should never need to store metadata of external declarations.")
+
     override fun <R, D> accept(visitor: IrElementVisitor<R, D>, data: D): R {
         return visitor.visitSimpleFunction(this, data)
     }
@@ -155,4 +159,4 @@ class Fir2IrLazySimpleFunction(
 
         body = body?.transform(transformer, data)
     }
-}
+}