[FE 1.0] Report recursive type checker problem as a warning till 1.9

^KT-48546

compiler/frontend/src/org/jetbrains/kotlin/diagnostics/Errors.java

@@ -796,7 +796,8 @@ public interface Errors {
     DiagnosticFactory1<PsiElement, String> NAME_SHADOWING = DiagnosticFactory1.create(WARNING, PositioningStrategies.FOR_REDECLARATION);
     DiagnosticFactory0<PsiElement> ACCESSOR_PARAMETER_NAME_SHADOWING = DiagnosticFactory0.create(WARNING);
 
-    DiagnosticFactoryForDeprecation0<KtExpression> TYPECHECKER_HAS_RUN_INTO_RECURSIVE_PROBLEM = DiagnosticFactoryForDeprecation0.create(LanguageFeature.ForbidRecursiveDelegateExpressions);
+    DiagnosticFactoryForDeprecation0<KtExpression> TYPECHECKER_HAS_RUN_INTO_RECURSIVE_PROBLEM =
+            DiagnosticFactoryForDeprecation0.create(LanguageFeature.ForbidRecursiveDelegateExpressions);
 
     // Checking call arguments
 

compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/DiagnosticReporterByTrackingStrategy.kt

@@ -75,7 +75,11 @@ class DiagnosticReporterByTrackingStrategy(
                 trace,
                 (diagnostic as NoValueForParameter).parameterDescriptor
             )
-            TypeCheckerHasRanIntoRecursion::class.java -> tracingStrategy.recursiveType(trace)
+            TypeCheckerHasRanIntoRecursion::class.java -> {
+                val shouldReportErrorsOnRecursiveTypeInsidePlusAssignment =
+                    context.languageVersionSettings.supportsFeature(LanguageFeature.ReportErrorsOnRecursiveTypeInsidePlusAssignment)
+                tracingStrategy.recursiveType(trace, shouldReportErrorsOnRecursiveTypeInsidePlusAssignment)
+            }
             InstantiationOfAbstractClass::class.java -> tracingStrategy.instantiationOfAbstractClass(trace)
             AbstractSuperCall::class.java -> {
                 val superExpression = (diagnostic as AbstractSuperCall).receiver.psiExpression as? KtSuperExpression

compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/tasks/AbstractTracingStrategy.java

@@ -22,6 +22,7 @@ import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.jetbrains.kotlin.descriptors.*;
 import org.jetbrains.kotlin.diagnostics.Diagnostic;
+import org.jetbrains.kotlin.diagnostics.DiagnosticFactory0;
 import org.jetbrains.kotlin.diagnostics.DiagnosticUtilsKt;
 import org.jetbrains.kotlin.lexer.KtToken;
 import org.jetbrains.kotlin.lexer.KtTokens;
@@ -138,10 +139,16 @@ public abstract class AbstractTracingStrategy implements TracingStrategy {
     }
 
     @Override
-    public void recursiveType(@NotNull BindingTrace trace) {
+    public void recursiveType(@NotNull BindingTrace trace, boolean shouldReportErrorsOnRecursiveTypeInsidePlusAssignment) {
         KtExpression expression = call.getCalleeExpression();
         if (expression == null) return;
-        trace.report(TYPECHECKER_HAS_RUN_INTO_RECURSIVE_PROBLEM.getErrorFactory().on(expression));
+        DiagnosticFactory0<KtExpression> factory;
+        if (shouldReportErrorsOnRecursiveTypeInsidePlusAssignment) {
+            factory = TYPECHECKER_HAS_RUN_INTO_RECURSIVE_PROBLEM.getErrorFactory();
+        } else {
+            factory = TYPECHECKER_HAS_RUN_INTO_RECURSIVE_PROBLEM.getWarningFactory();
+        }
+        trace.report(factory.on(expression));
     }
 
     @Override

compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/tasks/TracingStrategy.java

@@ -17,6 +17,7 @@
 package org.jetbrains.kotlin.resolve.calls.tasks;
 
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.kotlin.config.LanguageVersionSettings;
 import org.jetbrains.kotlin.descriptors.*;
 import org.jetbrains.kotlin.psi.Call;
 import org.jetbrains.kotlin.resolve.BindingTrace;
@@ -82,7 +83,7 @@ public interface TracingStrategy {
         ) {}
 
         @Override
-        public void recursiveType(@NotNull BindingTrace trace) {}
+        public void recursiveType(@NotNull BindingTrace trace, boolean shouldReportErrorsOnRecursiveTypeInsidePlusAssignment) {}
 
         @Override
         public void instantiationOfAbstractClass(@NotNull BindingTrace trace) {}
@@ -147,7 +148,7 @@ public interface TracingStrategy {
             @NotNull Collection<? extends ResolvedCall<D>> descriptors
     );
 
-    void recursiveType(@NotNull BindingTrace trace);
+    void recursiveType(@NotNull BindingTrace trace, boolean shouldReportErrorsOnRecursiveTypeInsidePlusAssignment);
 
     void instantiationOfAbstractClass(@NotNull BindingTrace trace);
 

compiler/frontend/src/org/jetbrains/kotlin/types/expressions/ControlStructureTypingUtils.java

@@ -585,7 +585,7 @@ public class ControlStructureTypingUtils {
         }
 
         @Override
-        public void recursiveType(@NotNull BindingTrace trace) {
+        public void recursiveType(@NotNull BindingTrace trace, boolean shouldReportErrorsOnRecursiveTypeInsidePlusAssignment) {
             logError();
         }