[FIR] Add ArrayEqualityOpCanBeReplacedWithEquals checker

compiler/fir/analysis-tests/testData/extendedCheckers/ArrayEqualityCanBeReplacedWithEquals.kt

@@ -0,0 +1,17 @@
+// WITH_RUNTIME
+
+fun foo(p: Int) {
+    val a = arrayOf(1, 2, 3)
+    val b = arrayOf(3, 2, 1)
+
+    if (a <!ARRAY_EQUALITY_OPERATOR_CAN_BE_REPLACED_WITH_EQUALS!>==<!> b) { }
+}
+
+fun testsFromIdea() {
+    val a = arrayOf("a")
+    val b = a
+    val c: Any? = null
+    a <!ARRAY_EQUALITY_OPERATOR_CAN_BE_REPLACED_WITH_EQUALS!>==<!> b
+    a == c
+    a <!ARRAY_EQUALITY_OPERATOR_CAN_BE_REPLACED_WITH_EQUALS!>!=<!> b
+}

compiler/fir/analysis-tests/testData/extendedCheckers/ArrayEqualityCanBeReplacedWithEquals.txt

@@ -0,0 +1,18 @@
+FILE: ArrayEqualityCanBeReplacedWithEquals.kt
+    public final fun foo(p: R|kotlin/Int|): R|kotlin/Unit| {
+        lval a: R|kotlin/Array<kotlin/Int>| = R|kotlin/arrayOf|<R|kotlin/Int|>(vararg(Int(1), Int(2), Int(3)))
+        lval b: R|kotlin/Array<kotlin/Int>| = R|kotlin/arrayOf|<R|kotlin/Int|>(vararg(Int(3), Int(2), Int(1)))
+        when () {
+            ==(R|<local>/a|, R|<local>/b|) ->  {
+            }
+        }
+
+    }
+    public final fun testsFromIdea(): R|kotlin/Unit| {
+        lval a: R|kotlin/Array<kotlin/String>| = R|kotlin/arrayOf|<R|kotlin/String|>(vararg(String(a)))
+        lval b: R|kotlin/Array<kotlin/String>| = R|<local>/a|
+        lval c: R|kotlin/Any?| = Null(null)
+        ==(R|<local>/a|, R|<local>/b|)
+        ==(R|<local>/a|, R|<local>/c|)
+        !=(R|<local>/a|, R|<local>/b|)
+    }

compiler/fir/analysis-tests/tests/org/jetbrains/kotlin/fir/ExtendedFirDiagnosticsTestGenerated.java

@@ -28,6 +28,11 @@ public class ExtendedFirDiagnosticsTestGenerated extends AbstractExtendedFirDiag
         KotlinTestUtils.assertAllTestsPresentByMetadataWithExcluded(this.getClass(), new File("compiler/fir/analysis-tests/testData/extendedCheckers"), Pattern.compile("^([^.]+)\\.kt$"), null, true);
     }
 
+    @TestMetadata("ArrayEqualityCanBeReplacedWithEquals.kt")
+    public void testArrayEqualityCanBeReplacedWithEquals() throws Exception {
+        runTest("compiler/fir/analysis-tests/testData/extendedCheckers/ArrayEqualityCanBeReplacedWithEquals.kt");
+    }
+
     @TestMetadata("RedundantExplicitTypeChecker.kt")
     public void testRedundantExplicitTypeChecker() throws Exception {
         runTest("compiler/fir/analysis-tests/testData/extendedCheckers/RedundantExplicitTypeChecker.kt");

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/expression/ExtendedExpressionCheckers.kt

@@ -5,9 +5,13 @@
 
 package org.jetbrains.kotlin.fir.analysis.checkers.expression
 
+import org.jetbrains.kotlin.fir.analysis.checkers.extended.ArrayEqualityCanBeReplacedWithEquals
 import org.jetbrains.kotlin.fir.analysis.checkers.extended.CanBeReplacedWithOperatorAssignmentChecker
 
 object ExtendedExpressionCheckers : ExpressionCheckers() {
+    override val expressionCheckers: List<FirBasicExpresionChecker> = listOf(
+        ArrayEqualityCanBeReplacedWithEquals
+    )
     override val variableAssignmentCheckers: List<FirVariableAssignmentChecker> = listOf(
         CanBeReplacedWithOperatorAssignmentChecker
     )

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/extended/ArrayEqualityCanBeReplacedWithEquals.kt

@@ -0,0 +1,34 @@
+/*
+ * Copyright 2010-2020 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.fir.analysis.checkers.extended
+
+import org.jetbrains.kotlin.fir.analysis.checkers.context.CheckerContext
+import org.jetbrains.kotlin.fir.analysis.checkers.expression.FirBasicExpresionChecker
+import org.jetbrains.kotlin.fir.analysis.diagnostics.DiagnosticReporter
+import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.ARRAY_EQUALITY_OPERATOR_CAN_BE_REPLACED_WITH_EQUALS
+import org.jetbrains.kotlin.fir.expressions.FirEqualityOperatorCall
+import org.jetbrains.kotlin.fir.expressions.FirOperation
+import org.jetbrains.kotlin.fir.expressions.FirStatement
+import org.jetbrains.kotlin.fir.expressions.arguments
+import org.jetbrains.kotlin.fir.psi
+import org.jetbrains.kotlin.fir.symbols.StandardClassIds
+import org.jetbrains.kotlin.fir.toFirPsiSourceElement
+import org.jetbrains.kotlin.fir.types.classId
+import org.jetbrains.kotlin.fir.types.coneType
+
+object ArrayEqualityCanBeReplacedWithEquals : FirBasicExpresionChecker() {
+    override fun check(equality: FirStatement, context: CheckerContext, reporter: DiagnosticReporter) {
+        if (equality !is FirEqualityOperatorCall) return
+        if (equality.operation != FirOperation.EQ && equality.operation != FirOperation.NOT_EQ) return
+        val left = equality.arguments.getOrNull(0) ?: return
+        val right = equality.arguments.getOrNull(1) ?: return
+
+        if (left.typeRef.coneType.classId != StandardClassIds.Array) return
+        if (right.typeRef.coneType.classId != StandardClassIds.Array) return
+
+        reporter.report(equality.psi?.children?.get(1)?.toFirPsiSourceElement(), ARRAY_EQUALITY_OPERATOR_CAN_BE_REPLACED_WITH_EQUALS)
+    }
+}

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/collectors/components/ExpressionCheckersDiagnosticComponent.kt

@@ -79,6 +79,10 @@ class ExpressionCheckersDiagnosticComponent(collector: AbstractDiagnosticCollect
         runCheck { checkers.expressionCheckers.check(getClassCall, data, it) }
     }
 
+    override fun visitEqualityOperatorCall(equalityOperatorCall: FirEqualityOperatorCall, data: CheckerContext) {
+        runCheck { checkers.expressionCheckers.check(equalityOperatorCall, data, it) }
+    }
+
     override fun visitVariableAssignment(variableAssignment: FirVariableAssignment, data: CheckerContext) {
         runCheck { checkers.variableAssignmentCheckers.check(variableAssignment, data, it) }
     }

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirErrors.kt

@@ -91,4 +91,5 @@ object FirErrors {
     val REDUNDANT_EXPLICIT_TYPE by warning0<FirSourceElement, PsiElement>()
     val CAN_BE_VAL by warning0<FirSourceElement, PsiElement>()
     val CAN_BE_REPLACED_WITH_OPERATOR_ASSIGNMENT by warning0<FirSourceElement, PsiElement>()
+    val ARRAY_EQUALITY_OPERATOR_CAN_BE_REPLACED_WITH_EQUALS by warning0<FirSourceElement, PsiElement>()
 }