forked from detekt/detekt
/
UnnecessaryNotNullCheck.kt
61 lines (55 loc) · 2.16 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 org.jetbrains.kotlin.psi.KtCallExpression
import org.jetbrains.kotlin.psi.KtExpression
import org.jetbrains.kotlin.psi.psiUtil.getCallNameExpression
import org.jetbrains.kotlin.resolve.BindingContext
import org.jetbrains.kotlin.resolve.calls.util.getType
import org.jetbrains.kotlin.types.typeUtil.TypeNullability
import org.jetbrains.kotlin.types.typeUtil.nullability
/**
* 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,
"Unnecessary not-null check detected.",
Debt.FIVE_MINS,
)
override fun visitCallExpression(expression: KtCallExpression) {
super.visitCallExpression(expression)
if (bindingContext == BindingContext.EMPTY) return
val callName = expression.getCallNameExpression()?.text
if (callName == "requireNotNull" || callName == "checkNotNull") {
val type = (expression.valueArguments[0].lastChild as KtExpression).getType(bindingContext)
if (type?.nullability() == TypeNullability.NOT_NULL) {
report(
CodeSmell(
issue = issue,
entity = Entity.from(expression),
message = "`${expression.text}` contains an unnecessary `$callName`",
)
)
}
}
}
}