Rule 6.1.5: Explicit supertype qualification should not be used if th…

…ere is not clash between called methods (#458)

* rule 6.1.5

### What's done:
   Implemented rule 6.1.5
  Added documentation

diktat-analysis.yml

@@ -366,3 +366,7 @@
 - name: COMPACT_OBJECT_INITIALIZATION
   enabled: true
   configuration: {}
+# Checks explicit supertype qualification
+- name: USELESS_SUPERTYPE
+  enabled: true
+  configuration: {}

diktat-rules/src/main/kotlin/generated/WarningNames.kt

@@ -213,4 +213,6 @@ public object WarningNames {
     public const val CUSTOM_GETTERS_SETTERS: String = "CUSTOM_GETTERS_SETTERS"
 
     public const val COMPACT_OBJECT_INITIALIZATION: String = "COMPACT_OBJECT_INITIALIZATION"
+
+    public const val USELESS_SUPERTYPE: String = "USELESS_SUPERTYPE"
 }

diktat-rules/src/main/kotlin/org/cqfn/diktat/ruleset/constants/Warnings.kt

@@ -128,6 +128,7 @@ enum class Warnings(private val canBeAutoCorrected: Boolean, private val warn: S
     TRIVIAL_ACCESSORS_ARE_NOT_RECOMMENDED(true, "trivial property accessors are not recommended"),
     CUSTOM_GETTERS_SETTERS(false, "Custom getters and setters are not recommended, use class methods instead"),
     COMPACT_OBJECT_INITIALIZATION(true, "class instance can be initialized in `apply` block"),
+    USELESS_SUPERTYPE(true,"unnecessary supertype specification"),
     ;
 
     /**

diktat-rules/src/main/kotlin/org/cqfn/diktat/ruleset/rules/DiktatRuleSetProvider.kt

@@ -65,6 +65,7 @@ class DiktatRuleSetProvider(private val diktatConfigFile: String = "diktat-analy
                 ::PackageNaming,
                 ::IdentifierNaming,
                 // code structure
+                ::UselessSupertype,
                 ::ClassLikeStructuresOrderRule,
                 ::WhenMustHaveElseRule,
                 ::BracesInConditionalsAndLoopsRule,

diktat-rules/src/main/kotlin/org/cqfn/diktat/ruleset/rules/UselessSupertype.kt

@@ -0,0 +1,138 @@
+package org.cqfn.diktat.ruleset.rules
+
+import com.pinterest.ktlint.core.Rule
+import com.pinterest.ktlint.core.ast.ElementType.CALL_EXPRESSION
+import com.pinterest.ktlint.core.ast.ElementType.CLASS
+import com.pinterest.ktlint.core.ast.ElementType.CLASS_BODY
+import com.pinterest.ktlint.core.ast.ElementType.CLASS_KEYWORD
+import com.pinterest.ktlint.core.ast.ElementType.DOT_QUALIFIED_EXPRESSION
+import com.pinterest.ktlint.core.ast.ElementType.FILE
+import com.pinterest.ktlint.core.ast.ElementType.FUN
+import com.pinterest.ktlint.core.ast.ElementType.IDENTIFIER
+import com.pinterest.ktlint.core.ast.ElementType.MODIFIER_LIST
+import com.pinterest.ktlint.core.ast.ElementType.OPEN_KEYWORD
+import com.pinterest.ktlint.core.ast.ElementType.REFERENCE_EXPRESSION
+import com.pinterest.ktlint.core.ast.ElementType.SUPER_EXPRESSION
+import com.pinterest.ktlint.core.ast.ElementType.SUPER_TYPE_CALL_ENTRY
+import com.pinterest.ktlint.core.ast.ElementType.SUPER_TYPE_ENTRY
+import com.pinterest.ktlint.core.ast.ElementType.SUPER_TYPE_LIST
+import com.pinterest.ktlint.core.ast.ElementType.TYPE_REFERENCE
+import com.pinterest.ktlint.core.ast.parent
+import org.cqfn.diktat.common.config.rules.RulesConfig
+import org.cqfn.diktat.ruleset.constants.EmitType
+import org.cqfn.diktat.ruleset.constants.Warnings.USELESS_SUPERTYPE
+import org.cqfn.diktat.ruleset.utils.*
+import org.jetbrains.kotlin.com.intellij.lang.ASTNode
+import org.jetbrains.kotlin.psi.psiUtil.siblings
+
+/**
+ * rule 6.1.5
+ * Explicit supertype qualification should not be used if there is not clash between called methods
+ * fixme can't fix supertypes that are defined in other files.
+ */
+class UselessSupertype(private val configRules: List<RulesConfig>) : Rule("useless-override") {
+
+    companion object {
+        private val SUPER_TYPE = listOf(SUPER_TYPE_CALL_ENTRY, SUPER_TYPE_ENTRY)
+    }
+
+    private lateinit var emitWarn: EmitType
+    private var isFixMode: Boolean = false
+
+    override fun visit(node: ASTNode,
+                       autoCorrect: Boolean,
+                       emit: (offset: Int, errorMessage: String, canBeAutoCorrected: Boolean) -> Unit) {
+        emitWarn = emit
+        isFixMode = autoCorrect
+
+        if (node.elementType == CLASS)
+            checkClass(node)
+    }
+
+    private fun checkClass(node: ASTNode) {
+        val superNodes = node.findChildByType(SUPER_TYPE_LIST)?.findAllNodesWithCondition({ it.elementType in SUPER_TYPE })?.takeIf { it.isNotEmpty() } ?: return
+        val qualifiedSuperCalls = node.findAllNodesWithSpecificType(DOT_QUALIFIED_EXPRESSION)
+                .mapNotNull { findFunWithSuper(it) }.ifEmpty { return }
+        if (superNodes.size == 1) {
+            qualifiedSuperCalls.map { removeSupertype(it.first) }
+        } else {
+            handleManyImpl(superNodes, qualifiedSuperCalls)
+        }
+    }
+
+    private fun handleManyImpl(superNodes: List<ASTNode>, overrideNodes: List<Pair<ASTNode, ASTNode>>) {
+        val uselessSuperType = findAllSupers(superNodes, overrideNodes.map { it.second.text })
+                ?.filter { it.value == 1 } // filtering methods whose names occur only once
+                ?.map { it.key } // take their names
+                ?: return
+        overrideNodes
+                .filter {
+                    it.second.text in uselessSuperType
+                }.map {
+                    removeSupertype(it.first)
+                }
+    }
+
+    @Suppress("UnsafeCallOnNullableType")
+    private fun removeSupertype(node: ASTNode) {
+        USELESS_SUPERTYPE.warnAndFix(configRules, emitWarn, isFixMode, node.text, node.startOffset, node) {
+            val startNode = node.parent({ it.elementType == SUPER_EXPRESSION })!!.findChildByType(REFERENCE_EXPRESSION)!!
+            val lastNode = startNode.siblings(true).last()
+            startNode.treeParent.removeRange(startNode.treeNext, lastNode)
+            startNode.treeParent.removeChild(lastNode)
+        }
+    }
+
+    /**
+     * Method finds pair of identifier supertype and method name else return null
+     * example: super<A>.foo() -> return Pair(A, foo)
+     *          super.foo() -> null
+     * @param node - node of type DOT_QUALIFIED_EXPRESSION
+     *
+     * @return pair of identifier
+     */
+    @Suppress("UnsafeCallOnNullableType")
+    private fun findFunWithSuper(node: ASTNode): Pair<ASTNode, ASTNode>? {
+        return Pair(
+                node.findChildByType(SUPER_EXPRESSION)
+                        ?.findChildByType(TYPE_REFERENCE)
+                        ?.findAllNodesWithSpecificType(IDENTIFIER)
+                        ?.firstOrNull() ?: return null,
+                node.findChildByType(CALL_EXPRESSION)
+                        ?.findAllNodesWithSpecificType(IDENTIFIER)
+                        ?.firstOrNull() ?: return null)
+    }
+
+    /**
+     * The method looks in the same file for all super interfaces or a class, in each it looks for methods
+     * that can be overridden and creates a map with a key - the name of the method and value - the number of times it meets
+     *
+     * @param superTypeList - list of identifiers super classes
+     * @param methodsName - name of overrides methods
+     *
+     * @return map name of method and the number of times it meets
+     */
+    @Suppress("UnsafeCallOnNullableType")
+    private fun findAllSupers(superTypeList: List<ASTNode>, methodsName: List<String>): Map<String, Int>? {
+        val fileNode = superTypeList.first().parent({ it.elementType == FILE })!!
+        val superNodesIdentifier = superTypeList.map { it.findAllNodesWithSpecificType(IDENTIFIER).first().text }
+        val superNodes = fileNode.findAllNodesWithCondition({ superClass ->
+            superClass.elementType == CLASS &&
+                    superClass.getIdentifierName()!!.text in superNodesIdentifier
+        }).mapNotNull { it.findChildByType(CLASS_BODY) }
+        if (superNodes.size != superTypeList.size)
+            return null
+        val functionNameMap = hashMapOf<String, Int>()
+        superNodes.forEach { classBody ->
+            val overrideFunctions = classBody.findAllNodesWithSpecificType(FUN)
+                    .filter {
+                        (if (classBody.treeParent.hasChildOfType(CLASS_KEYWORD)) it.findChildByType(MODIFIER_LIST)!!.hasChildOfType(OPEN_KEYWORD) else true) &&
+                                it.getIdentifierName()!!.text in methodsName
+                    }
+            overrideFunctions.forEach {
+                functionNameMap.compute(it.getIdentifierName()!!.text) { _, oldValue -> (oldValue ?: 0) + 1}
+            }
+        }
+        return functionNameMap.toMap()
+    }
+}

diktat-rules/src/main/resources/diktat-analysis-huawei.yml

@@ -363,5 +363,9 @@
   configuration: { }
 # Checks if class instantiation can be wrapped in `apply` for better readability
 - name: COMPACT_OBJECT_INITIALIZATION
+  enabled: true
+  configuration: {}
+# Checks explicit supertype qualification
+- name: USELESS_SUPERTYPE
   enabled: true
   configuration: {}

diktat-rules/src/main/resources/diktat-analysis.yml

@@ -365,5 +365,9 @@
   configuration: { }
 # Checks if class instantiation can be wrapped in `apply` for better readability
 - name: COMPACT_OBJECT_INITIALIZATION
+  enabled: true
+  configuration: {}
+# Checks explicit supertype qualification
+- name: USELESS_SUPERTYPE
   enabled: true
   configuration: {}

diktat-rules/src/test/kotlin/org/cqfn/diktat/ruleset/chapter6/UselessSupertypeFixTest.kt

@@ -0,0 +1,22 @@
+package org.cqfn.diktat.ruleset.chapter6
+
+import generated.WarningNames
+import org.cqfn.diktat.util.FixTestBase
+import org.cqfn.diktat.ruleset.rules.UselessSupertype
+import org.junit.jupiter.api.Tag
+import org.junit.jupiter.api.Test
+
+class UselessSupertypeFixTest : FixTestBase("test/paragraph6/useless-override", ::UselessSupertype) {
+
+    @Test
+    @Tag(WarningNames.USELESS_SUPERTYPE)
+    fun `fix example with one super`() {
+        fixAndCompare("UselessOverrideExpected.kt", "UselessOverrideTest.kt")
+    }
+
+    @Test
+    @Tag(WarningNames.USELESS_SUPERTYPE)
+    fun `fix several super`() {
+        fixAndCompare("SeveralSuperTypesExpected.kt", "SeveralSuperTypesTest.kt")
+    }
+}

diktat-rules/src/test/kotlin/org/cqfn/diktat/ruleset/chapter6/UselessSupertypeWarnTest.kt

@@ -0,0 +1,91 @@
+package org.cqfn.diktat.ruleset.chapter6
+
+import com.pinterest.ktlint.core.LintError
+import generated.WarningNames
+import org.cqfn.diktat.ruleset.constants.Warnings.USELESS_SUPERTYPE
+import org.cqfn.diktat.ruleset.rules.DIKTAT_RULE_SET_ID
+import org.cqfn.diktat.ruleset.rules.UselessSupertype
+import org.cqfn.diktat.util.LintTestBase
+import org.junit.jupiter.api.Tag
+import org.junit.jupiter.api.Test
+
+class UselessSupertypeWarnTest: LintTestBase(::UselessSupertype) {
+
+    private val ruleId = "$DIKTAT_RULE_SET_ID:useless-override"
+
+    @Test
+    @Tag(WarningNames.USELESS_SUPERTYPE)
+    fun `check simple wrong example`() {
+        lintMethod(
+                """
+                    open class Rectangle {
+                        open fun draw() { /* ... */ }
+                    }
+                    
+                    class Square() : Rectangle() {
+                        override fun draw() {
+                        /**
+                         *
+                         * hehe
+                         */
+                            super<Rectangle>.draw()
+                        }
+                    }
+                    
+                    class Square2() : Rectangle() {
+                        override fun draw() {
+                            //hehe
+                            /*
+                                hehe
+                            */
+                            super<Rectangle>.draw()
+                        }
+                    }
+                    
+                    class Square2() : Rectangle() {
+                        override fun draw() {
+                            val q = super.draw()
+                        }
+                    }
+                    
+                    class A: Runnable {
+                        override fun run() {
+                        
+                        }
+                    }
+                """.trimMargin(),
+                LintError(11,35, ruleId, "${USELESS_SUPERTYPE.warnText()} Rectangle", true),
+                LintError(21,35, ruleId, "${USELESS_SUPERTYPE.warnText()} Rectangle", true)
+        )
+    }
+
+    @Test
+    @Tag(WarningNames.USELESS_SUPERTYPE)
+    fun `check example with two super`() {
+        lintMethod(
+                """
+                    open class Rectangle {
+                        open fun draw() { /* ... */ }
+                    }
+                    
+                    interface KK {
+                        fun draw() {}
+                        fun kk() {}
+                    }
+                    
+                    class Square2() : Rectangle(), KK {
+                        override fun draw() {
+                            super<Rectangle>.draw()
+                            super<KK>.draw()
+                        }
+                        
+                        private fun goo() {
+                            super<KK>.kk()
+                        }
+
+                    }
+                """.trimMargin(),
+                LintError(17,35, ruleId, "${USELESS_SUPERTYPE.warnText()} KK", true)
+        )
+    }
+}

diktat-rules/src/test/resources/test/paragraph6/useless-override/SeveralSuperTypesExpected.kt

@@ -0,0 +1,28 @@
+package test.paragraph6.`useless-override`
+
+open class A {
+    open fun foo(){}
+}
+
+interface C {
+    fun foo(){}
+    fun goo(){}
+}
+
+class B: A(){
+    override fun foo() {
+        super.foo()
+    }
+}
+
+class D: A(), C {
+    override fun foo() {
+        super<C>.foo()
+        super<A>.foo()
+        super.goo()
+    }
+
+    private fun qwe(){
+        val q = super.goo()
+    }
+}

diktat-rules/src/test/resources/test/paragraph6/useless-override/SeveralSuperTypesTest.kt

@@ -0,0 +1,28 @@
+package test.paragraph6.`useless-override`
+
+open class A {
+    open fun foo(){}
+}
+
+interface C {
+    fun foo(){}
+    fun goo(){}
+}
+
+class B: A(){
+    override fun foo() {
+        super<A>.foo()
+    }
+}
+
+class D: A(), C {
+    override fun foo() {
+        super<C>.foo()
+        super<A>.foo()
+        super<C>.goo()
+    }
+
+    private fun qwe(){
+        val q = super<C>.goo()
+    }
+}