/
UnnecessaryNotNullCheck.kt
75 lines (65 loc) · 2.51 KB
/
UnnecessaryNotNullCheck.kt
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package io.gitlab.arturbosch.detekt.rules.bugs
import io.gitlab.arturbosch.detekt.api.CodeSmell
import io.gitlab.arturbosch.detekt.api.Config
import io.gitlab.arturbosch.detekt.api.Debt
import io.gitlab.arturbosch.detekt.api.Entity
import io.gitlab.arturbosch.detekt.api.Issue
import io.gitlab.arturbosch.detekt.api.Rule
import io.gitlab.arturbosch.detekt.api.Severity
import io.gitlab.arturbosch.detekt.api.internal.RequiresTypeResolution
import io.gitlab.arturbosch.detekt.rules.getDataFlowAwareTypes
import io.gitlab.arturbosch.detekt.rules.isCalling
import org.jetbrains.kotlin.name.FqName
import org.jetbrains.kotlin.psi.KtCallExpression
import org.jetbrains.kotlin.resolve.BindingContext
import org.jetbrains.kotlin.types.isNullable
/**
* Reports unnecessary not-null checks with `requireNotNull` or `checkNotNull` that can be removed by the user.
*
* <noncompliant>
* var string = "foo"
* println(requireNotNull(string))
* </noncompliant>
*
* <compliant>
* var string : String? = "foo"
* println(requireNotNull(string))
* </compliant>
*/
@RequiresTypeResolution
class UnnecessaryNotNullCheck(config: Config = Config.empty) : Rule(config) {
override val issue = Issue(
"UnnecessaryNotNullCheck",
Severity.Defect,
"Remove unnecessary not-null checks on non-null types.",
Debt.FIVE_MINS,
)
@Suppress("ReturnCount")
override fun visitCallExpression(expression: KtCallExpression) {
super.visitCallExpression(expression)
if (bindingContext == BindingContext.EMPTY) return
val compilerResources = compilerResources ?: return
val callee = expression.calleeExpression ?: return
val argument = expression.valueArguments.firstOrNull()?.getArgumentExpression() ?: return
if (!expression.isCalling(notNullCheckFunctionFqNames, bindingContext)) return
val dataFlowAwareTypes = argument.getDataFlowAwareTypes(
bindingContext,
compilerResources.languageVersionSettings,
compilerResources.dataFlowValueFactory
)
if (dataFlowAwareTypes.all { it.isNullable() }) return
report(
CodeSmell(
issue = issue,
entity = Entity.from(expression),
message = "Using `${callee.text}` on non-null `${argument.text}` is unnecessary",
)
)
}
companion object {
private val notNullCheckFunctionFqNames = listOf(
FqName("kotlin.requireNotNull"),
FqName("kotlin.checkNotNull"),
)
}
}