[FIR] Introduce FirReturnExpressionChecker

compiler/fir/checkers/checkers-component-generator/src/org/jetbrains/kotlin/fir/checkers/generator/Main.kt

@@ -22,6 +22,7 @@ fun main(args: Array<String>) {
         alias<FirVariableAssignment>("VariableAssignmentChecker")
         alias<FirTryExpression>("TryExpressionChecker")
         alias<FirWhenExpression>("WhenExpressionChecker")
+        alias<FirReturnExpression>("ReturnExpressionChecker")
     }
 
     val declarationPackage = "org.jetbrains.kotlin.fir.analysis.checkers.declaration"

compiler/fir/checkers/gen/org/jetbrains/kotlin/fir/analysis/checkers/expression/ComposedExpressionCheckers.kt

@@ -25,6 +25,8 @@ internal class ComposedExpressionCheckers : ExpressionCheckers() {
         get() = _tryExpressionCheckers
     override val whenExpressionCheckers: Set<FirWhenExpressionChecker>
         get() = _whenExpressionCheckers
+    override val returnExpressionCheckers: Set<FirReturnExpressionChecker>
+        get() = _returnExpressionCheckers
 
     private val _basicExpressionCheckers: MutableSet<FirBasicExpressionChecker> = mutableSetOf()
     private val _qualifiedAccessCheckers: MutableSet<FirQualifiedAccessChecker> = mutableSetOf()
@@ -32,6 +34,7 @@ internal class ComposedExpressionCheckers : ExpressionCheckers() {
     private val _variableAssignmentCheckers: MutableSet<FirVariableAssignmentChecker> = mutableSetOf()
     private val _tryExpressionCheckers: MutableSet<FirTryExpressionChecker> = mutableSetOf()
     private val _whenExpressionCheckers: MutableSet<FirWhenExpressionChecker> = mutableSetOf()
+    private val _returnExpressionCheckers: MutableSet<FirReturnExpressionChecker> = mutableSetOf()
 
     @CheckersComponentInternal
     internal fun register(checkers: ExpressionCheckers) {
@@ -41,5 +44,6 @@ internal class ComposedExpressionCheckers : ExpressionCheckers() {
         _variableAssignmentCheckers += checkers.variableAssignmentCheckers
         _tryExpressionCheckers += checkers.tryExpressionCheckers
         _whenExpressionCheckers += checkers.whenExpressionCheckers
+        _returnExpressionCheckers += checkers.returnExpressionCheckers
     }
 }

compiler/fir/checkers/gen/org/jetbrains/kotlin/fir/analysis/checkers/expression/ExpressionCheckers.kt

@@ -23,6 +23,7 @@ abstract class ExpressionCheckers {
     open val variableAssignmentCheckers: Set<FirVariableAssignmentChecker> = emptySet()
     open val tryExpressionCheckers: Set<FirTryExpressionChecker> = emptySet()
     open val whenExpressionCheckers: Set<FirWhenExpressionChecker> = emptySet()
+    open val returnExpressionCheckers: Set<FirReturnExpressionChecker> = emptySet()
 
     @CheckersComponentInternal internal val allBasicExpressionCheckers: Set<FirBasicExpressionChecker> get() = basicExpressionCheckers
     @CheckersComponentInternal internal val allQualifiedAccessCheckers: Set<FirQualifiedAccessChecker> get() = qualifiedAccessCheckers + basicExpressionCheckers
@@ -30,4 +31,5 @@ abstract class ExpressionCheckers {
     @CheckersComponentInternal internal val allVariableAssignmentCheckers: Set<FirVariableAssignmentChecker> get() = variableAssignmentCheckers + basicExpressionCheckers
     @CheckersComponentInternal internal val allTryExpressionCheckers: Set<FirTryExpressionChecker> get() = tryExpressionCheckers + basicExpressionCheckers
     @CheckersComponentInternal internal val allWhenExpressionCheckers: Set<FirWhenExpressionChecker> get() = whenExpressionCheckers + basicExpressionCheckers
+    @CheckersComponentInternal internal val allReturnExpressionCheckers: Set<FirReturnExpressionChecker> get() = returnExpressionCheckers + basicExpressionCheckers
 }

compiler/fir/checkers/gen/org/jetbrains/kotlin/fir/analysis/checkers/expression/FirExpressionCheckerAliases.kt

@@ -12,6 +12,7 @@ package org.jetbrains.kotlin.fir.analysis.checkers.expression
 
 import org.jetbrains.kotlin.fir.expressions.FirFunctionCall
 import org.jetbrains.kotlin.fir.expressions.FirQualifiedAccessExpression
+import org.jetbrains.kotlin.fir.expressions.FirReturnExpression
 import org.jetbrains.kotlin.fir.expressions.FirStatement
 import org.jetbrains.kotlin.fir.expressions.FirTryExpression
 import org.jetbrains.kotlin.fir.expressions.FirVariableAssignment
@@ -23,3 +24,4 @@ typealias FirFunctionCallChecker = FirExpressionChecker<FirFunctionCall>
 typealias FirVariableAssignmentChecker = FirExpressionChecker<FirVariableAssignment>
 typealias FirTryExpressionChecker = FirExpressionChecker<FirTryExpression>
 typealias FirWhenExpressionChecker = FirExpressionChecker<FirWhenExpression>
+typealias FirReturnExpressionChecker = FirExpressionChecker<FirReturnExpression>

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

@@ -97,6 +97,10 @@ class ExpressionCheckersDiagnosticComponent(
         checkers.allVariableAssignmentCheckers.check(variableAssignment, data, reporter)
     }
 
+    override fun visitReturnExpression(returnExpression: FirReturnExpression, data: CheckerContext) {
+        checkers.returnExpressionCheckers.check(returnExpression, data, reporter)
+    }
+
     private fun <E : FirStatement> Collection<FirExpressionChecker<E>>.check(
         expression: E,
         context: CheckerContext,