[IR] Mark IrExpressionBodyImpl with an opt-in annotation

KT-59318

plugins/atomicfu/atomicfu-compiler/src/org/jetbrains/kotlinx/atomicfu/compiler/backend/common/AbstractAtomicfuIrBuilder.kt

@@ -81,7 +81,7 @@ abstract class AbstractAtomicfuIrBuilder(
             visibility = DescriptorVisibilities.PRIVATE
             origin = AbstractAtomicSymbols.ATOMICFU_GENERATED_FIELD
         }.apply {
-            initializer = initValue?.let { IrExpressionBodyImpl(it) }
+            initializer = initValue?.let(context.irFactory::createExpressionBody)
             this.annotations = annotations + atomicSymbols.volatileAnnotationConstructorCall
             this.parent = parentContainer
         }
@@ -103,7 +103,7 @@ abstract class AbstractAtomicfuIrBuilder(
             visibility = DescriptorVisibilities.PRIVATE
             origin = AbstractAtomicSymbols.ATOMICFU_GENERATED_FIELD
         }.apply {
-            this.initializer = IrExpressionBodyImpl(
+            this.initializer = context.irFactory.createExpressionBody(
                 newAtomicArray(arrayClass, size, dispatchReceiver)
             )
             this.annotations = annotations
@@ -150,7 +150,7 @@ abstract class AbstractAtomicfuIrBuilder(
             this.visibility = DescriptorVisibilities.PRIVATE
             origin = AbstractAtomicSymbols.ATOMICFU_GENERATED_FIELD
         }.apply {
-            initializer = IrExpressionBodyImpl(
+            initializer = context.irFactory.createExpressionBody(
                 IrConstructorCallImpl.fromSymbolOwner(
                     irClass.defaultType,
                     irClass.primaryConstructor!!.symbol

plugins/kotlinx-serialization/kotlinx-serialization.backend/src/org/jetbrains/kotlinx/serialization/compiler/backend/ir/IrBuilderWithPluginContext.kt

@@ -180,7 +180,7 @@ interface IrBuilderWithPluginContext {
                 field.startOffset,
                 field.endOffset
             )
-            field.initializer = IrExpressionBodyImpl(builder.initializer())
+            field.initializer = factory.createExpressionBody(builder.initializer())
             field.annotations += createAnnotationCallWithoutArgs(compilerContext.jvmFieldClassSymbol)
         }
     }