Rename: FirSourceElement.getChildren() -> getChild() + minor fixes

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

@@ -9,32 +9,32 @@ import com.intellij.psi.tree.IElementType
 import com.intellij.psi.tree.TokenSet
 import org.jetbrains.kotlin.fir.*
 
-fun FirSourceElement.getChildren(type: IElementType, index: Int = 0, depth: Int = -1): FirSourceElement? {
+fun FirSourceElement.getChild(type: IElementType, index: Int = 0, depth: Int = -1): FirSourceElement? {
-    return getChildren(setOf(type), index, depth)
+    return getChild(setOf(type), index, depth)
 }
 
-fun FirSourceElement.getChildren(types: TokenSet, index: Int = 0, depth: Int = -1): FirSourceElement? {
+fun FirSourceElement.getChild(types: TokenSet, index: Int = 0, depth: Int = -1): FirSourceElement? {
-    return getChildren(types.types.toSet(), index, depth)
+    return getChild(types.types.toSet(), index, depth)
 }
 
-fun FirSourceElement.getChildren(types: Set<IElementType>, index: Int = 0, depth: Int = -1): FirSourceElement? {
+fun FirSourceElement.getChild(types: Set<IElementType>, index: Int = 0, depth: Int = -1): FirSourceElement? {
     return when (this) {
         is FirPsiSourceElement<*> -> {
-            getChildren(types, index, depth)
+            getChild(types, index, depth)
         }
         is FirLightSourceElement -> {
-            getChildren(types, index, depth)
+            getChild(types, index, depth)
         }
         else -> null
     }
 }
 
-private fun FirPsiSourceElement<*>.getChildren(types: Set<IElementType>, index: Int, depth: Int): FirSourceElement? {
+private fun FirPsiSourceElement<*>.getChild(types: Set<IElementType>, index: Int, depth: Int): FirSourceElement? {
     val visitor = PsiElementFinderByType(types, index, depth)
     return visitor.find(psi)?.toFirPsiSourceElement()
 }
 
-private fun FirLightSourceElement.getChildren(types: Set<IElementType>, index: Int, depth: Int): FirSourceElement? {
+private fun FirLightSourceElement.getChild(types: Set<IElementType>, index: Int, depth: Int): FirSourceElement? {
     val visitor = LighterTreeElementFinderByType(tree, types, index, depth)
 
     return visitor.find(lightNode)?.let { it.toFirLightSourceElement(it.startOffset, it.endOffset, tree) }

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

@@ -9,7 +9,7 @@ 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.analysis.getChildren
+import org.jetbrains.kotlin.fir.analysis.getChild
 import org.jetbrains.kotlin.fir.expressions.FirEqualityOperatorCall
 import org.jetbrains.kotlin.fir.expressions.FirOperation
 import org.jetbrains.kotlin.fir.expressions.FirStatement
@@ -29,7 +29,7 @@ object ArrayEqualityCanBeReplacedWithEquals : FirBasicExpresionChecker() {
         if (left.typeRef.coneType.classId != StandardClassIds.Array) return
         if (right.typeRef.coneType.classId != StandardClassIds.Array) return
 
-        val source = expression.source?.getChildren(setOf(KtTokens.EQEQ, KtTokens.EXCLEQ))
+        val source = expression.source?.getChild(setOf(KtTokens.EQEQ, KtTokens.EXCLEQ))
         reporter.report(source, ARRAY_EQUALITY_OPERATOR_CAN_BE_REPLACED_WITH_EQUALS)
     }
 }

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

@@ -16,7 +16,7 @@ import org.jetbrains.kotlin.fir.analysis.checkers.context.CheckerContext
 import org.jetbrains.kotlin.fir.analysis.checkers.expression.FirExpressionChecker
 import org.jetbrains.kotlin.fir.analysis.diagnostics.DiagnosticReporter
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors
-import org.jetbrains.kotlin.fir.analysis.getChildren
+import org.jetbrains.kotlin.fir.analysis.getChild
 import org.jetbrains.kotlin.fir.expressions.FirFunctionCall
 import org.jetbrains.kotlin.fir.expressions.FirVariableAssignment
 import org.jetbrains.kotlin.fir.expressions.toResolvedCallableSymbol
@@ -62,7 +62,7 @@ object CanBeReplacedWithOperatorAssignmentChecker : FirExpressionChecker<FirVari
         }
 
         if (needToReport) {
-            val source = expression.source?.getChildren(setOf(KtTokens.EQ))
+            val source = expression.source?.getChild(setOf(KtTokens.EQ))
             reporter.report(source, FirErrors.CAN_BE_REPLACED_WITH_OPERATOR_ASSIGNMENT)
         }
 

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

@@ -17,7 +17,7 @@ import org.jetbrains.kotlin.fir.analysis.cfa.TraverseDirection
 import org.jetbrains.kotlin.fir.analysis.cfa.traverse
 import org.jetbrains.kotlin.fir.analysis.diagnostics.DiagnosticReporter
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors
-import org.jetbrains.kotlin.fir.analysis.getChildren
+import org.jetbrains.kotlin.fir.analysis.getChild
 import org.jetbrains.kotlin.fir.references.FirResolvedNamedReference
 import org.jetbrains.kotlin.fir.resolve.dfa.cfg.*
 import org.jetbrains.kotlin.fir.symbols.impl.FirPropertySymbol
@@ -48,7 +48,7 @@ object CanBeValChecker : AbstractFirPropertyInitializationChecker() {
         var lastDestructuredVariables = 0
 
         for ((symbol, value) in propertiesCharacteristics) {
-            val source = symbol.fir.source?.getChildren(setOf(KtTokens.VAL_KEYWORD, KtTokens.VAR_KEYWORD), depth = 1)
+            val source = symbol.fir.source?.getChild(setOf(KtTokens.VAL_KEYWORD, KtTokens.VAR_KEYWORD), depth = 1)
             if (symbol.isDestructuring) {
                 lastDestructuringSource = source
                 lastDestructuredVariables = symbol.getDestructuringChildrenCount() ?: continue

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

@@ -8,20 +8,16 @@ package org.jetbrains.kotlin.fir.analysis.checkers.extended
 import org.jetbrains.kotlin.descriptors.ClassKind
 import org.jetbrains.kotlin.descriptors.Modality
 import org.jetbrains.kotlin.fir.FirFakeSourceElementKind
-import org.jetbrains.kotlin.fir.FirSourceElement
-import org.jetbrains.kotlin.fir.analysis.checkers.FirModifier
 import org.jetbrains.kotlin.fir.analysis.checkers.context.CheckerContext
 import org.jetbrains.kotlin.fir.analysis.checkers.declaration.FirMemberDeclarationChecker
 import org.jetbrains.kotlin.fir.analysis.checkers.implicitModality
-import org.jetbrains.kotlin.fir.analysis.checkers.source
 import org.jetbrains.kotlin.fir.analysis.checkers.toToken
 import org.jetbrains.kotlin.fir.analysis.diagnostics.DiagnosticReporter
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.REDUNDANT_MODALITY_MODIFIER
-import org.jetbrains.kotlin.fir.analysis.getChildren
+import org.jetbrains.kotlin.fir.analysis.getChild
 import org.jetbrains.kotlin.fir.declarations.FirClass
 import org.jetbrains.kotlin.fir.declarations.FirMemberDeclaration
 import org.jetbrains.kotlin.fir.declarations.modality
-import org.jetbrains.kotlin.lexer.KtTokens
 
 object RedundantModalityModifierChecker : FirMemberDeclarationChecker() {
     override fun check(declaration: FirMemberDeclaration, context: CheckerContext, reporter: DiagnosticReporter) {
@@ -37,16 +33,7 @@ object RedundantModalityModifierChecker : FirMemberDeclarationChecker() {
 
         if (modality != implicitModality) return
 
-        val modalityModifierSource = declaration.source?.getChildren(modality.toToken(), depth = 2)
+        val modalityModifierSource = declaration.source?.getChild(modality.toToken(), depth = 2)
         reporter.report(modalityModifierSource, REDUNDANT_MODALITY_MODIFIER)
     }
-
-    private fun Collection<FirModifier<*>>.modalitySource(): FirSourceElement? {
-        return this.firstOrNull {
-            it.token == KtTokens.FINAL_KEYWORD
-                    || it.token == KtTokens.OPEN_KEYWORD
-                    || it.token == KtTokens.SEALED_KEYWORD
-                    || it.token == KtTokens.ABSTRACT_KEYWORD
-        }?.source
-    }
 }

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

@@ -16,7 +16,7 @@ import org.jetbrains.kotlin.fir.analysis.checkers.context.CheckerContext
 import org.jetbrains.kotlin.fir.analysis.checkers.declaration.FirBasicDeclarationChecker
 import org.jetbrains.kotlin.fir.analysis.diagnostics.DiagnosticReporter
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors
-import org.jetbrains.kotlin.fir.analysis.getChildren
+import org.jetbrains.kotlin.fir.analysis.getChild
 import org.jetbrains.kotlin.fir.declarations.*
 import org.jetbrains.kotlin.lexer.KtModifierKeywordToken
 import org.jetbrains.kotlin.lexer.KtTokens
@@ -56,7 +56,7 @@ object RedundantVisibilityModifierChecker : FirBasicDeclarationChecker() {
             && declaration.setter?.visibility == Visibilities.Public
         ) return
 
-        reporter.report(declaration.source?.getChildren(KtTokens.VISIBILITY_MODIFIERS), FirErrors.REDUNDANT_VISIBILITY_MODIFIER)
+        reporter.report(declaration.source?.getChild(KtTokens.VISIBILITY_MODIFIERS), FirErrors.REDUNDANT_VISIBILITY_MODIFIER)
     }
 
     private fun FirDeclaration.implicitVisibility(context: CheckerContext): Visibility {
@@ -127,10 +127,6 @@ object RedundantVisibilityModifierChecker : FirBasicDeclarationChecker() {
     private val CheckerContext.containingPropertyVisibility
         get() = (this.containingDeclarations.last() as? FirProperty)?.visibility
 
-
-    private val FirModifier<*>.isVisibilityModifier
-        get() = this.token.toVisibilityOrNull() != null
-
     private fun List<FirLightModifier>.visibilityOrNull() =
         firstOrNull { it.token.toVisibilityOrNull() != null }?.token?.toVisibilityOrNull()
 

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

@@ -17,7 +17,7 @@ import org.jetbrains.kotlin.fir.analysis.checkers.getContainingClass
 import org.jetbrains.kotlin.fir.analysis.checkers.isIterator
 import org.jetbrains.kotlin.fir.analysis.diagnostics.DiagnosticReporter
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors
-import org.jetbrains.kotlin.fir.analysis.getChildren
+import org.jetbrains.kotlin.fir.analysis.getChild
 import org.jetbrains.kotlin.fir.expressions.FirFunctionCall
 import org.jetbrains.kotlin.fir.references.FirResolvedNamedReference
 import org.jetbrains.kotlin.fir.resolve.dfa.cfg.*
@@ -203,5 +203,5 @@ object UnusedChecker : FirControlFlowChecker() {
         get() = fir.initializer?.source?.kind == FirFakeSourceElementKind.DesugaredForLoop
 
     private val FirPropertySymbol.identifierSource: FirSourceElement?
-        get() = fir.source?.getChildren(KtTokens.IDENTIFIER, 0, 1)
+        get() = fir.source?.getChild(KtTokens.IDENTIFIER, 0, 1)
 }

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

@@ -343,10 +343,10 @@ class FirDefaultErrorMessages : DefaultErrorMessages.Extension {
             map.put(ARRAY_EQUALITY_OPERATOR_CAN_BE_REPLACED_WITH_EQUALS, "Replace '==' with 'Arrays.equals'")
             map.put(EMPTY_RANGE, "Range is empty")
             map.put(REDUNDANT_SETTER_PARAMETER_TYPE, "Redundant setter parameter type")
-            map.put(UNUSED_VARIABLE, "Unused variable")
+            map.put(UNUSED_VARIABLE, "Variable is unused")
             map.put(ASSIGNED_VALUE_IS_NEVER_READ, "Assigned value is never read")
-            map.put(VARIABLE_INITIALIZER_IS_REDUNDANT, "Initialized is redundant")
+            map.put(VARIABLE_INITIALIZER_IS_REDUNDANT, "Initializer is redundant")
-            map.put(VARIABLE_NEVER_READ, "Variable never read")
+            map.put(VARIABLE_NEVER_READ, "Variable is never read")
         }
     }
 }