[FIR] Implement deprecation for accessing private operators from public inline function

This only affects delegation operators as well as the for-loop-related
next and hasNext operators.
All the other operators worked correctly before.
In K2, the previously mentioned operator calls will be flagged with a
deprecation error and will become and error in 2.1.

#KT-59782 Fixed

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

@@ -1651,6 +1651,11 @@ object DIAGNOSTICS_LIST : DiagnosticList("FirErrors") {
             parameter<Symbol>("referencedDeclaration")
         }
 
+        val NON_PUBLIC_CALL_FROM_PUBLIC_INLINE_DEPRECATION by warning<KtElement>(PositioningStrategy.REFERENCE_BY_QUALIFIED) {
+            parameter<Symbol>("inlineDeclaration")
+            parameter<Symbol>("referencedDeclaration")
+        }
+
         val PROTECTED_CONSTRUCTOR_CALL_FROM_PUBLIC_INLINE by error<KtElement>(PositioningStrategy.REFERENCE_BY_QUALIFIED) {
             parameter<Symbol>("inlineDeclaration")
             parameter<Symbol>("referencedDeclaration")

compiler/fir/checkers/gen/org/jetbrains/kotlin/fir/analysis/diagnostics/FirErrors.kt

@@ -833,6 +833,7 @@ object FirErrors {
     val NULLABLE_INLINE_PARAMETER: KtDiagnosticFactory2<FirValueParameterSymbol, FirBasedSymbol<*>> by error2<KtDeclaration, FirValueParameterSymbol, FirBasedSymbol<*>>()
     val RECURSION_IN_INLINE: KtDiagnosticFactory1<FirBasedSymbol<*>> by error1<KtElement, FirBasedSymbol<*>>(SourceElementPositioningStrategies.REFERENCE_BY_QUALIFIED)
     val NON_PUBLIC_CALL_FROM_PUBLIC_INLINE: KtDiagnosticFactory2<FirBasedSymbol<*>, FirBasedSymbol<*>> by error2<KtElement, FirBasedSymbol<*>, FirBasedSymbol<*>>(SourceElementPositioningStrategies.REFERENCE_BY_QUALIFIED)
+    val NON_PUBLIC_CALL_FROM_PUBLIC_INLINE_DEPRECATION: KtDiagnosticFactory2<FirBasedSymbol<*>, FirBasedSymbol<*>> by warning2<KtElement, FirBasedSymbol<*>, FirBasedSymbol<*>>(SourceElementPositioningStrategies.REFERENCE_BY_QUALIFIED)
     val PROTECTED_CONSTRUCTOR_CALL_FROM_PUBLIC_INLINE: KtDiagnosticFactory2<FirBasedSymbol<*>, FirBasedSymbol<*>> by error2<KtElement, FirBasedSymbol<*>, FirBasedSymbol<*>>(SourceElementPositioningStrategies.REFERENCE_BY_QUALIFIED)
     val PROTECTED_CALL_FROM_PUBLIC_INLINE_ERROR: KtDiagnosticFactory2<FirBasedSymbol<*>, FirBasedSymbol<*>> by error2<KtElement, FirBasedSymbol<*>, FirBasedSymbol<*>>(SourceElementPositioningStrategies.REFERENCE_BY_QUALIFIED)
     val PROTECTED_CALL_FROM_PUBLIC_INLINE: KtDiagnosticFactory2<FirBasedSymbol<*>, FirBasedSymbol<*>> by warning2<KtElement, FirBasedSymbol<*>, FirBasedSymbol<*>>(SourceElementPositioningStrategies.REFERENCE_BY_QUALIFIED)

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

@@ -14,6 +14,7 @@ import org.jetbrains.kotlin.descriptors.EffectiveVisibility
 import org.jetbrains.kotlin.descriptors.Visibilities
 import org.jetbrains.kotlin.descriptors.Visibility
 import org.jetbrains.kotlin.diagnostics.DiagnosticReporter
+import org.jetbrains.kotlin.diagnostics.KtDiagnosticFactory2
 import org.jetbrains.kotlin.diagnostics.reportOn
 import org.jetbrains.kotlin.fir.*
 import org.jetbrains.kotlin.fir.analysis.checkers.MppCheckerKind
@@ -26,6 +27,7 @@ import org.jetbrains.kotlin.fir.declarations.*
 import org.jetbrains.kotlin.fir.declarations.utils.*
 import org.jetbrains.kotlin.fir.expressions.*
 import org.jetbrains.kotlin.fir.references.FirSuperReference
+import org.jetbrains.kotlin.fir.references.symbol
 import org.jetbrains.kotlin.fir.resolve.toSymbol
 import org.jetbrains.kotlin.fir.resolve.transformers.publishedApiEffectiveVisibility
 import org.jetbrains.kotlin.fir.symbols.FirBasedSymbol
@@ -91,7 +93,7 @@ object FirInlineDeclarationChecker : FirFunctionChecker(MppCheckerKind.Common) {
             ) {
                 reporter.reportOn(
                     source,
-                    FirErrors.NON_PUBLIC_CALL_FROM_PUBLIC_INLINE,
+                    getNonPublicCallFromPublicInlineFactory(accessExpression, source, context),
                     inlineFunction.symbol,
                     accessedSymbol,
                     context
@@ -106,6 +108,24 @@ object FirInlineDeclarationChecker : FirFunctionChecker(MppCheckerKind.Common) {
             )
         }
 
+        private fun getNonPublicCallFromPublicInlineFactory(
+            accessExpression: FirStatement,
+            source: KtSourceElement,
+            context: CheckerContext,
+        ): KtDiagnosticFactory2<FirBasedSymbol<*>, FirBasedSymbol<*>> {
+            if (!context.languageVersionSettings.supportsFeature(LanguageFeature.ProhibitPrivateOperatorCallInInline)) {
+                val isDelegatedPropertyAccessor = source.kind == KtFakeSourceElementKind.DelegatedPropertyAccessor
+                val isForLoopButNotIteratorCall = source.kind == KtFakeSourceElementKind.DesugaredForLoop &&
+                        accessExpression.toReference(context.session)?.symbol?.memberDeclarationNameOrNull != OperatorNameConventions.ITERATOR
+
+                if (isDelegatedPropertyAccessor || isForLoopButNotIteratorCall) {
+                    return FirErrors.NON_PUBLIC_CALL_FROM_PUBLIC_INLINE_DEPRECATION
+                }
+            }
+
+            return FirErrors.NON_PUBLIC_CALL_FROM_PUBLIC_INLINE
+        }
+
         private fun EffectiveVisibility.isReachableDueToLocalDispatchReceiver(access: FirStatement, context: CheckerContext): Boolean {
             val receiverType = access.localDispatchReceiver(context) ?: return false
             val receiverProtected = EffectiveVisibility.Protected(receiverType.typeConstructor(context.session.typeContext))

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

@@ -6,6 +6,7 @@
 package org.jetbrains.kotlin.fir.analysis.diagnostics
 
 import com.intellij.openapi.util.io.FileUtil
+import org.jetbrains.kotlin.config.LanguageFeature
 import org.jetbrains.kotlin.diagnostics.KtDiagnosticFactoryToRendererMap
 import org.jetbrains.kotlin.diagnostics.KtDiagnosticRenderers.CLASS_ID
 import org.jetbrains.kotlin.diagnostics.KtDiagnosticRenderers.COLLECTION
@@ -504,6 +505,7 @@ import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.PLATFORM_CLASS_MA
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.COMPILER_REQUIRED_ANNOTATION_AMBIGUITY
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.MULTIPLE_LABELS_ARE_FORBIDDEN
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.EXPECT_AND_ACTUAL_IN_THE_SAME_MODULE
+import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.NON_PUBLIC_CALL_FROM_PUBLIC_INLINE_DEPRECATION
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.POTENTIALLY_NON_REPORTED_ANNOTATION
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.PRE_RELEASE_CLASS
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.PRIMARY_CONSTRUCTOR_DELEGATION_CALL_EXPECTED
@@ -2427,6 +2429,13 @@ object FirErrorsDefaultMessages : BaseDiagnosticRendererFactory() {
         )
         map.put(RECURSION_IN_INLINE, "Inline function ''{0}'' cannot be recursive.", SYMBOL)
         map.put(NON_PUBLIC_CALL_FROM_PUBLIC_INLINE, "Public-API inline function cannot access non-public-API ''{0}''.", SYMBOL, SYMBOL)
+        map.put(
+            NON_PUBLIC_CALL_FROM_PUBLIC_INLINE_DEPRECATION,
+            "Public-API inline function cannot access non-public-API ''{0}''. " +
+                    "This will become an error in Kotlin ${LanguageFeature.ProhibitPrivateOperatorCallInInline.sinceVersion?.versionString}.",
+            SYMBOL,
+            SYMBOL
+        )
         map.put(
             PROTECTED_CONSTRUCTOR_CALL_FROM_PUBLIC_INLINE,
             "Protected constructor call from public-API inline function is deprecated.",