[FIR] Fix redundant modality modifier checker

Fixed function FirDeclaration.hasBody() and some others improvement

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

@@ -1,3 +1,27 @@
+// Interface
+interface Interface {
+    // Redundant
+    <!REDUNDANT_MODALITY_MODIFIER!>open<!> val gav: Int
+        get() = 42
+    // Redundant
+    <!REDUNDANT_MODALITY_MODIFIER!>abstract<!> fun foo()
+    // Redundant
+    private <!REDUNDANT_MODALITY_MODIFIER!>final<!> fun bar() {}
+}
+interface B {
+    <!REDUNDANT_MODALITY_MODIFIER!>abstract<!> var bar: Unit
+    <!REDUNDANT_MODALITY_MODIFIER!>abstract<!> fun foo()
+}
+
+expect abstract class AbstractClass : Foo {
+    abstract override fun foo()
+
+    abstract fun bar()
+
+    abstract val baz: Int
+}
+
+
 // Abstract
 abstract class Base {
     // Redundant final
@@ -23,16 +47,6 @@ open class OpenDerived : Base() {
 }
 // Redundant final
 <!REDUNDANT_MODALITY_MODIFIER!>final<!> class Final
-// Interface
-interface Interface {
-    // Redundant
-    <!REDUNDANT_MODALITY_MODIFIER!>abstract<!> fun foo()
-    // Redundant
-    private <!REDUNDANT_MODALITY_MODIFIER!>final<!> fun bar() {}
-    // Redundant
-    <!REDUNDANT_MODALITY_MODIFIER!>open<!> val gav: Int
-        get() = 42
-}
 // Derived interface
 interface Derived : Interface {
     // Redundant

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

@@ -1,4 +1,37 @@
 FILE: RedundantModalityModifierChecker.kt
+    public abstract interface Interface : R|kotlin/Any| {
+        public open val gav: R|kotlin/Int|
+            public get(): R|kotlin/Int| {
+                ^ Int(42)
+            }
+
+        public abstract fun foo(): R|kotlin/Unit|
+
+        private final fun bar(): R|kotlin/Unit| {
+        }
+
+    }
+    public abstract interface B : R|kotlin/Any| {
+        public abstract var bar: R|kotlin/Unit|
+            public get(): R|kotlin/Unit|
+            public set(value: R|kotlin/Unit|): R|kotlin/Unit|
+
+        public abstract fun foo(): R|kotlin/Unit|
+
+    }
+    public abstract expect class AbstractClass : R|ERROR CLASS: Symbol not found, for `Foo`| {
+        public expect constructor(): R|AbstractClass| {
+            super<R|kotlin/Any|>()
+        }
+
+        public abstract expect override fun foo(): R|kotlin/Unit|
+
+        public abstract expect fun bar(): R|kotlin/Unit|
+
+        public abstract expect val baz: R|kotlin/Int|
+            public get(): R|kotlin/Int|
+
+    }
     public abstract class Base : R|kotlin/Any| {
         public constructor(): R|Base| {
             super<R|kotlin/Any|>()
@@ -42,18 +75,6 @@ FILE: RedundantModalityModifierChecker.kt
             super<R|kotlin/Any|>()
         }
 
-    }
-    public abstract interface Interface : R|kotlin/Any| {
-        public abstract fun foo(): R|kotlin/Unit|
-
-        private final fun bar(): R|kotlin/Unit| {
-        }
-
-        public open val gav: R|kotlin/Int|
-            public get(): R|kotlin/Int| {
-                ^ Int(42)
-            }
-
     }
     public abstract interface Derived : R|Interface| {
         public open override fun foo(): R|kotlin/Unit| {

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/FirHelpers.kt

@@ -12,6 +12,7 @@ import org.jetbrains.kotlin.fir.FirSymbolOwner
 import org.jetbrains.kotlin.fir.analysis.checkers.context.CheckerContext
 import org.jetbrains.kotlin.fir.declarations.*
 import org.jetbrains.kotlin.fir.expressions.FirQualifiedAccessExpression
+import org.jetbrains.kotlin.fir.expressions.impl.FirEmptyExpressionBlock
 import org.jetbrains.kotlin.fir.expressions.impl.FirSingleExpressionBlock
 import org.jetbrains.kotlin.fir.references.FirResolvedNamedReference
 import org.jetbrains.kotlin.fir.resolve.firSymbolProvider
@@ -268,7 +269,7 @@ fun FirMemberDeclaration.implicitModality(context: CheckerContext): KtModifierKe
 private fun FirDeclaration.modifierListOrNull() = (this.source.getModifierList() as? FirPsiModifierList)?.modifierList
 
 private fun FirDeclaration.hasBody(): Boolean = when (this) {
-    is FirSimpleFunction -> this.body != null && this.body !is FirSingleExpressionBlock
-    is FirProperty -> this.setter != null || this.getter != null
+    is FirSimpleFunction -> this.body != null && this.body !is FirEmptyExpressionBlock
+    is FirProperty -> this.setter?.body !is FirEmptyExpressionBlock? || this.getter?.body !is FirEmptyExpressionBlock?
     else -> false
 }

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/declaration/ExtendedDeclarationCheckers.kt

@@ -0,0 +1,16 @@
+/*
+ * 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.declaration
+
+import org.jetbrains.kotlin.fir.analysis.checkers.extended.RedundantModalityModifierChecker
+import org.jetbrains.kotlin.fir.analysis.checkers.extended.RedundantVisibilityModifierChecker
+
+object ExtendedDeclarationCheckers : DeclarationCheckers() {
+    override val declarationCheckers = listOf(RedundantVisibilityModifierChecker, RedundantVisibilityModifierChecker)
+
+    override val memberDeclarationCheckers = listOf(RedundantModalityModifierChecker)
+
+}

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

@@ -16,6 +16,7 @@ import org.jetbrains.kotlin.fir.declarations.FirMemberDeclaration
 import org.jetbrains.kotlin.fir.psi
 import org.jetbrains.kotlin.fir.toFirPsiSourceElement
 import org.jetbrains.kotlin.lexer.KtModifierKeywordToken
+import org.jetbrains.kotlin.lexer.KtTokens
 import org.jetbrains.kotlin.psi.KtDeclaration
 import org.jetbrains.kotlin.psi.psiUtil.modalityModifier