[FIR] Fix top-level property initialization checks in scripts

- While `collectionInitializationInfo` unwrapped a script's top-level
  declarations, `check` forgot to do it, so a script effectively had no
  top-level properties in the mind of the checker.

^KT-63286 fixed

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

@@ -34,29 +34,32 @@ import org.jetbrains.kotlin.lexer.KtTokens
 // See old FE's [DeclarationsChecker]
 object FirTopLevelPropertiesChecker : FirFileChecker() {
     override fun check(declaration: FirFile, context: CheckerContext, reporter: DiagnosticReporter) {
-        val info = declaration.collectionInitializationInfo(context, reporter)
-        for (innerDeclaration in declaration.declarations) {
-            if (innerDeclaration is FirProperty) {
-                val symbol = innerDeclaration.symbol
-                val isDefinitelyAssigned = info?.get(symbol)?.isDefinitelyVisited() == true
-                checkProperty(containingDeclaration = null, innerDeclaration, isDefinitelyAssigned, context, reporter, reachable = true)
-            }
+        val topLevelProperties = declaration.effectiveTopLevelProperties
+        val info = declaration.collectionInitializationInfo(topLevelProperties, context, reporter)
+        for (topLevelProperty in topLevelProperties) {
+            val symbol = topLevelProperty.symbol
+            val isDefinitelyAssigned = info?.get(symbol)?.isDefinitelyVisited() == true
+            checkProperty(containingDeclaration = null, topLevelProperty, isDefinitelyAssigned, context, reporter, reachable = true)
         }
     }
 
+    /**
+     * Scripts are nested as a single declaration under [FirFile]s and contain their own statements. To properly check all "top-level"
+     * properties, script statements need to be unwrapped.
+     */
+    private val FirFile.effectiveTopLevelProperties: List<FirProperty>
+        get() = when (val script = declarations.singleOrNull()) {
+            is FirScript -> script.statements.filterIsInstance<FirProperty>()
+            else -> declarations.filterIsInstance<FirProperty>()
+        }
+
     private fun FirFile.collectionInitializationInfo(
+        topLevelProperties: List<FirProperty>,
         context: CheckerContext,
         reporter: DiagnosticReporter,
     ): PropertyInitializationInfo? {
         val graph = (this as? FirControlFlowGraphOwner)?.controlFlowGraphReference?.controlFlowGraph ?: return null
 
-        // Scripts are nested as a single declaration under FirFiles and contain their own statements. To properly check all "top-level"
-        // properties, script statements need to be unwrapped.
-        val topLevelProperties = when (val script = declarations.singleOrNull()) {
-            is FirScript -> script.statements.filterIsInstance<FirProperty>()
-            else -> declarations.filterIsInstance<FirProperty>()
-        }
-
         val propertySymbols = topLevelProperties.mapNotNullTo(mutableSetOf()) { declaration ->
             declaration.symbol.takeIf { it.requiresInitialization(isForInitialization = true) }
         }

compiler/testData/diagnostics/tests/script/topLevelPropertiesWithGetSet.fir.kts

@@ -16,10 +16,10 @@ get() = 42
 val testValLineBreakNoType
 get() = 42
 
-val testValLineBreakSemi: Int;
+<!MUST_BE_INITIALIZED!>val testValLineBreakSemi: Int<!>;
 <!VARIABLE_EXPECTED!><!UNRESOLVED_REFERENCE!>get<!>()<!> = 42
 
-val testValLineBreakSemiNoType;
+<!MUST_BE_INITIALIZED!>val testValLineBreakSemiNoType<!>;
 <!VARIABLE_EXPECTED!><!UNRESOLVED_REFERENCE!>get<!>()<!> = 42
 
 var testVarLineBreak: Int
@@ -30,10 +30,10 @@ var String.testExtVarLineBreak: Int
 get() = 42
 set(value) {}
 
-var testVarLineBreakSemi: Int;
+<!MUST_BE_INITIALIZED!>var testVarLineBreakSemi: Int<!>;
 <!VARIABLE_EXPECTED!><!UNRESOLVED_REFERENCE!>get<!>()<!> = 42
 <!UNRESOLVED_REFERENCE!>set<!>(<!UNRESOLVED_REFERENCE!>value<!>) {}
 
-var String.testExtVarLineBreakSemi: Int;
+<!EXTENSION_PROPERTY_MUST_HAVE_ACCESSORS_OR_BE_ABSTRACT!>var String.testExtVarLineBreakSemi: Int<!>;
 <!VARIABLE_EXPECTED!><!UNRESOLVED_REFERENCE!>get<!>()<!> = 42
 <!UNRESOLVED_REFERENCE!>set<!>(<!UNRESOLVED_REFERENCE!>value<!>) {}

compiler/testData/diagnostics/tests/script/topLevelPropertyInitialization.fir.kts

@@ -32,9 +32,9 @@ val d: String by simpleDelegate(d)
 val e: String by inPlaceDelegate { e }
 val f: String by notInPlaceDelegate { f }
 
-val g: Int
+<!MUST_BE_INITIALIZED!>val g: Int<!>
 val h = 1.also { <!VAL_REASSIGNMENT!>g<!> = 2 }
-val i: Int
+<!MUST_BE_INITIALIZED!>val i: Int<!>
 val j by lazy { <!VAL_REASSIGNMENT!>i<!> = 2; 1 }
 val k: Int
     get() {