org.jetbrains.kotlin.backend.wasm.lower.GenericReturnTypeLowering.kt Maven / Gradle / Ivy
/*
* Copyright 2010-2019 JetBrains s.r.o. and Kotlin Programming Language contributors.
* Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
*/
package org.jetbrains.kotlin.backend.wasm.lower
import org.jetbrains.kotlin.backend.common.FileLoweringPass
import org.jetbrains.kotlin.backend.common.IrElementTransformerVoidWithContext
import org.jetbrains.kotlin.backend.common.lower.createIrBuilder
import org.jetbrains.kotlin.backend.common.lower.irComposite
import org.jetbrains.kotlin.backend.wasm.WasmBackendContext
import org.jetbrains.kotlin.ir.backend.js.utils.erasedUpperBound
import org.jetbrains.kotlin.ir.backend.js.utils.realOverrideTarget
import org.jetbrains.kotlin.ir.builders.irImplicitCast
import org.jetbrains.kotlin.ir.declarations.IrFile
import org.jetbrains.kotlin.ir.declarations.IrSimpleFunction
import org.jetbrains.kotlin.ir.expressions.IrCall
import org.jetbrains.kotlin.ir.expressions.IrExpression
import org.jetbrains.kotlin.ir.symbols.IrSymbol
import org.jetbrains.kotlin.ir.types.*
import org.jetbrains.kotlin.ir.util.defaultType
import org.jetbrains.kotlin.ir.util.irCall
import org.jetbrains.kotlin.ir.util.isTypeParameter
import org.jetbrains.kotlin.ir.visitors.transformChildrenVoid
/**
* This lowering adds implicit casts in places where erased generic function return type
* differs from expected type on the call site.
*/
class GenericReturnTypeLowering(val context: WasmBackendContext) : FileLoweringPass {
override fun lower(irFile: IrFile) {
irFile.transformChildrenVoid(object : IrElementTransformerVoidWithContext() {
override fun visitCall(expression: IrCall): IrExpression =
transformGenericCall(
super.visitCall(expression) as IrCall,
currentScope!!.scope.scopeOwnerSymbol
)
})
}
private fun IrType.eraseUpperBoundType(): IrType {
val type = erasedUpperBound?.defaultType ?: return context.irBuiltIns.anyNType
return if (this.isNullable())
type.makeNullable()
else
type
}
private fun transformGenericCall(call: IrCall, scopeOwnerSymbol: IrSymbol): IrExpression {
val function: IrSimpleFunction =
call.symbol.owner as? IrSimpleFunction ?: return call
val erasedReturnType: IrType =
function.realOverrideTarget.returnType.eraseUpperBoundType()
val callType = call.type
if (erasedReturnType != call.type) {
if (callType.isNothing()) return call
if (erasedReturnType.isSubtypeOf(callType, context.typeSystem)) return call
// Erase type parameter from call return type
val newCall = irCall(
call,
function.symbol,
newReturnType = erasedReturnType,
newSuperQualifierSymbol = call.superQualifierSymbol
)
context.createIrBuilder(scopeOwnerSymbol).apply {
return irImplicitCast(newCall, call.type)
}
}
return call
}
}