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Cast nullable to non nullable type (#5653)
* New rule: report cast of nullable variable to non-null type * Add test case for CastNullableToNonNullableType rule * Refactor KtExpression utility to TypeUtils.kt Move isNullable and descriptor common utility that was common across NullableToStringCall.kt and CastNullableToNonNullableType.kt rules * Add test for unnecessary safe check chain * Make the parameters of isNullable non nullable Handle null compilerResources at the call site * Add apis to detekt-psi-utils.api * Make KtExpression.descriptor private * Add alternate compliant code
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72 changes: 72 additions & 0 deletions
72
...e/src/main/kotlin/io/gitlab/arturbosch/detekt/rules/bugs/CastNullableToNonNullableType.kt
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,72 @@ | ||
| 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.isNullable | ||
| import org.jetbrains.kotlin.lexer.KtTokens | ||
| import org.jetbrains.kotlin.psi.KtBinaryExpressionWithTypeRHS | ||
| import org.jetbrains.kotlin.psi.KtNullableType | ||
| import org.jetbrains.kotlin.utils.addToStdlib.ifFalse | ||
| import org.jetbrains.kotlin.utils.addToStdlib.ifTrue | ||
|
|
||
| /** | ||
| * Reports cast of nullable variable to non-null type. Cast like this can hide `null` | ||
| * problems in your code. The compliant code would be that which will correctly check | ||
| * for two things (nullability and type) and not just one (cast). | ||
| * | ||
| * <noncompliant> | ||
| * fun foo(bar: Any?) { | ||
| * val x = bar as String | ||
| * } | ||
| * </noncompliant> | ||
| * | ||
| * <compliant> | ||
| * fun foo(bar: Any?) { | ||
| * val x = checkNotNull(bar) as String | ||
| * } | ||
| * | ||
| * // Alternative | ||
| * fun foo(bar: Any?) { | ||
| * val x = (bar ?: error("null assertion message")) as String | ||
| * } | ||
| * </compliant> | ||
| */ | ||
| @RequiresTypeResolution | ||
| class CastNullableToNonNullableType(config: Config = Config.empty) : Rule(config) { | ||
| override val issue: Issue = Issue( | ||
| javaClass.simpleName, | ||
| Severity.Defect, | ||
| "Nullable type to non-null type cast is found. Consider using two assertions, " + | ||
| "`null` assertions and type cast", | ||
| Debt.FIVE_MINS | ||
| ) | ||
|
|
||
| @Suppress("ReturnCount") | ||
| override fun visitBinaryWithTypeRHSExpression(expression: KtBinaryExpressionWithTypeRHS) { | ||
| super.visitBinaryWithTypeRHSExpression(expression) | ||
|
|
||
| val operationReference = expression.operationReference | ||
| if (operationReference.getReferencedNameElementType() != KtTokens.AS_KEYWORD) return | ||
| if (expression.left.text == KtTokens.NULL_KEYWORD.value) return | ||
| val typeElement = expression.right?.typeElement ?: return | ||
| (typeElement is KtNullableType).ifTrue { return } | ||
| val compilerResourcesNonNull = compilerResources ?: return | ||
| expression.left.isNullable( | ||
| bindingContext, | ||
| compilerResourcesNonNull.languageVersionSettings, | ||
| compilerResourcesNonNull.dataFlowValueFactory, | ||
| shouldConsiderPlatformTypeAsNullable = true, | ||
| ).ifFalse { return } | ||
|
|
||
| val message = | ||
| "Use separate `null` assertion and type cast like ('(${expression.left.text} ?: " + | ||
| "error(\"null assertion message\")) as ${typeElement.text}') instead of '${expression.text}'." | ||
| report(CodeSmell(issue, Entity.from(operationReference), message)) | ||
| } | ||
| } |
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148 changes: 148 additions & 0 deletions
148
...c/test/kotlin/io/gitlab/arturbosch/detekt/rules/bugs/CastNullableToNonNullableTypeSpec.kt
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,148 @@ | ||
| package io.gitlab.arturbosch.detekt.rules.bugs | ||
|
|
||
| import io.gitlab.arturbosch.detekt.rules.KotlinCoreEnvironmentTest | ||
| import io.gitlab.arturbosch.detekt.test.assertThat | ||
| import io.gitlab.arturbosch.detekt.test.compileAndLintWithContext | ||
| import org.jetbrains.kotlin.cli.jvm.compiler.KotlinCoreEnvironment | ||
| import org.junit.jupiter.api.Test | ||
|
|
||
| @KotlinCoreEnvironmentTest | ||
| class CastNullableToNonNullableTypeSpec(private val env: KotlinCoreEnvironment) { | ||
| private val subject = CastNullableToNonNullableType() | ||
|
|
||
| @Test | ||
| fun `reports casting Nullable type to NonNullable type`() { | ||
| val code = """ | ||
| fun foo(bar: Any?) { | ||
| val x = bar as String | ||
| } | ||
| """.trimIndent() | ||
| val findings = subject.compileAndLintWithContext(env, code) | ||
| assertThat(findings).hasSize(1) | ||
| assertThat(findings).hasStartSourceLocation(2, 17) | ||
| assertThat(findings[0]).hasMessage( | ||
| "Use separate `null` assertion and type cast like " + | ||
| "('(bar ?: error(\"null assertion message\")) as String') instead of 'bar as String'." | ||
| ) | ||
| } | ||
|
|
||
| @Test | ||
| fun `reports casting Nullable value returned from a function call to NonNullable type`() { | ||
| val code = """ | ||
| fun foo(bar: Any?) { | ||
| bar() as Int | ||
| } | ||
| fun bar(): Int? { | ||
| return null | ||
| } | ||
| """.trimIndent() | ||
| val findings = subject.compileAndLintWithContext(env, code) | ||
| assertThat(findings).hasSize(1) | ||
| assertThat(findings).hasStartSourceLocation(2, 11) | ||
| assertThat(findings[0]).hasMessage( | ||
| "Use separate `null` assertion and type cast like " + | ||
| "('(bar() ?: error(\"null assertion message\")) as Int') instead of 'bar() as Int'." | ||
| ) | ||
| } | ||
|
|
||
| @Test | ||
| fun `reports casting of platform type to NonNullable type`() { | ||
| val code = """ | ||
| class Foo { | ||
| fun test() { | ||
| // getSimpleName() is not annotated with nullability information in the JDK, so compiler treats | ||
| // it as a platform type with unknown nullability. | ||
| val y = javaClass.simpleName as String | ||
| } | ||
| } | ||
| """.trimIndent() | ||
| val findings = subject.compileAndLintWithContext(env, code) | ||
| assertThat(findings).hasSize(1) | ||
| assertThat(findings).hasStartSourceLocation(5, 38) | ||
| assertThat(findings[0]).hasMessage( | ||
| "Use separate `null` assertion and type cast like " + | ||
| "('(javaClass.simpleName ?: error(\"null assertion message\")) as String') instead of " + | ||
| "'javaClass.simpleName as String'." | ||
| ) | ||
| } | ||
|
|
||
| @Test | ||
| fun `does not report unnecessary safe check chain to NonNullable type`() { | ||
| val code = """ | ||
| class Foo { | ||
| fun test() { | ||
| val z = 1?.and(2) as Int | ||
| } | ||
| } | ||
| """.trimIndent() | ||
| val findings = subject.compileAndLintWithContext(env, code) | ||
| assertThat(findings).isEmpty() | ||
| } | ||
|
|
||
| @Test | ||
| fun `does not report casting of Nullable type to NonNullable expression with assertion to NonNullable type`() { | ||
| val code = """ | ||
| fun foo(bar: Any?) { | ||
| val x = (bar ?: error("null assertion message")) as String | ||
| } | ||
| """.trimIndent() | ||
| val findings = subject.compileAndLintWithContext(env, code) | ||
| assertThat(findings).isEmpty() | ||
| } | ||
|
|
||
| @Test | ||
| fun `does not report casting of Nullable type to NonNullable expression with !! assertion to NonNullable type`() { | ||
| val code = """ | ||
| fun foo(bar: Any?) { | ||
| val x = bar!! as String | ||
| } | ||
| """.trimIndent() | ||
| val findings = subject.compileAndLintWithContext(env, code) | ||
| assertThat(findings).isEmpty() | ||
| } | ||
|
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||
| @Test | ||
| fun `does not report casting of Nullable type to NonNullable smart casted variable to NonNullable type`() { | ||
| val code = """ | ||
| fun foo(bar: Any?) { | ||
| val x = bar?.let { bar as String } | ||
| } | ||
| """.trimIndent() | ||
| val findings = subject.compileAndLintWithContext(env, code) | ||
| assertThat(findings).isEmpty() | ||
| } | ||
|
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||
| @Test | ||
| fun `does not report casting of NonNullable type to NonNullable type`() { | ||
| val code = """ | ||
| fun foo(bar: Any?) { | ||
| val x = bar as String? | ||
| } | ||
| """.trimIndent() | ||
| val findings = subject.compileAndLintWithContext(env, code) | ||
| assertThat(findings).isEmpty() | ||
| } | ||
|
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||
| @Test | ||
| fun `does not report safe casting of Nullable type to NonNullable type`() { | ||
| val code = """ | ||
| fun foo(bar: Any?) { | ||
| val x = bar as? String | ||
| } | ||
| """.trimIndent() | ||
| val findings = subject.compileAndLintWithContext(env, code) | ||
| assertThat(findings).isEmpty() | ||
| } | ||
|
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||
| @Test | ||
| fun `does not report as compile error will happen when null to NonNullable type`() { | ||
| val code = """ | ||
| fun foo(bar: Any?) { | ||
| val x = null as String | ||
| } | ||
| """.trimIndent() | ||
| val findings = subject.compileAndLintWithContext(env, code) | ||
| assertThat(findings).isEmpty() | ||
| } | ||
| } |