org.jetbrains.kotlin.types.expressions.SenselessComparisonChecker.kt Maven / Gradle / Ivy
/*
* Copyright 2010-2015 JetBrains s.r.o.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
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package org.jetbrains.kotlin.types.expressions
import org.jetbrains.kotlin.diagnostics.Errors
import org.jetbrains.kotlin.lexer.KtTokens
import org.jetbrains.kotlin.psi.KtBinaryExpression
import org.jetbrains.kotlin.psi.KtExpression
import org.jetbrains.kotlin.psi.KtPsiUtil
import org.jetbrains.kotlin.resolve.calls.context.ResolutionContext
import org.jetbrains.kotlin.resolve.calls.smartcasts.DataFlowValue
import org.jetbrains.kotlin.resolve.calls.smartcasts.DataFlowValueFactory
import org.jetbrains.kotlin.resolve.calls.smartcasts.Nullability
import org.jetbrains.kotlin.types.KotlinType
import org.jetbrains.kotlin.types.isError
object SenselessComparisonChecker {
@JvmStatic fun checkSenselessComparisonWithNull(
expression: KtBinaryExpression,
left: KtExpression,
right: KtExpression,
context: ResolutionContext<*>,
getType: (KtExpression) -> KotlinType?,
getNullability: (DataFlowValue) -> Nullability
) {
val expr =
when {
KtPsiUtil.isNullConstant(left) -> right
KtPsiUtil.isNullConstant(right) -> left
else -> return
}
val type = getType(expr)
if (type == null || type.isError) return
val operationSign = expression.operationReference
val value = DataFlowValueFactory.createDataFlowValue(expr, type, context)
val equality = operationSign.getReferencedNameElementType() == KtTokens.EQEQ || operationSign.getReferencedNameElementType() == KtTokens.EQEQEQ
val nullability = getNullability(value)
val expressionIsAlways =
when (nullability) {
Nullability.NULL -> equality
Nullability.NOT_NULL -> !equality
Nullability.IMPOSSIBLE -> false
else -> return
}
context.trace.report(Errors.SENSELESS_COMPARISON.on(expression, expression, expressionIsAlways))
}
}