Standardize context receiver parameter names

Previously, FIR used `_context_receiver_n` while FE10 used `<this>` for
all context receiver parameters. This commit changes the code in FE10
to follow the convention from FIR.

core/descriptors/src/org/jetbrains/kotlin/descriptors/impl/AbstractReceiverParameterDescriptor.java

@@ -20,6 +20,7 @@ import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.jetbrains.kotlin.descriptors.*;
 import org.jetbrains.kotlin.descriptors.annotations.Annotations;
+import org.jetbrains.kotlin.name.Name;
 import org.jetbrains.kotlin.name.SpecialNames;
 import org.jetbrains.kotlin.resolve.scopes.receivers.TransientReceiver;
 import org.jetbrains.kotlin.types.KotlinType;
@@ -36,6 +37,10 @@ public abstract class AbstractReceiverParameterDescriptor extends DeclarationDes
         super(annotations, SpecialNames.THIS);
     }
 
+    public AbstractReceiverParameterDescriptor(@NotNull Annotations annotations, @NotNull Name name) {
+        super(annotations, name);
+    }
+
     @Nullable
     @Override
     public ReceiverParameterDescriptor substitute(@NotNull TypeSubstitutor substitutor) {

core/descriptors/src/org/jetbrains/kotlin/descriptors/impl/FunctionDescriptorImpl.java

@@ -628,6 +628,7 @@ public abstract class FunctionDescriptorImpl extends DeclarationDescriptorNonRoo
 
         List<ReceiverParameterDescriptor> substitutedContextReceiverParameters = new ArrayList<ReceiverParameterDescriptor>();
         if (!configuration.newContextReceiverParameters.isEmpty()) {
+            int index = 0;
             for (ReceiverParameterDescriptor newContextReceiverParameter : configuration.newContextReceiverParameters) {
                 KotlinType substitutedContextReceiverType =
                         substitutor.substitute(newContextReceiverParameter.getType(), Variance.IN_VARIANCE);
@@ -637,7 +638,8 @@ public abstract class FunctionDescriptorImpl extends DeclarationDescriptorNonRoo
                 ReceiverParameterDescriptor substitutedContextReceiverParameter =
                         DescriptorFactory.createContextReceiverParameterForCallable(substitutedDescriptor, substitutedContextReceiverType,
                                                                                     ((ImplicitContextReceiver)newContextReceiverParameter.getValue()).getCustomLabelName(),
-                                                                                    newContextReceiverParameter.getAnnotations());
+                                                                                    newContextReceiverParameter.getAnnotations(),
+                                                                                    index++);
                 substitutedContextReceiverParameters.add(substitutedContextReceiverParameter);
 
                 wereChanges[0] |= substitutedContextReceiverType != newContextReceiverParameter.getType();

core/descriptors/src/org/jetbrains/kotlin/descriptors/impl/ReceiverParameterDescriptorImpl.java

@@ -20,6 +20,8 @@ import org.jetbrains.annotations.NotNull;
 import org.jetbrains.kotlin.descriptors.DeclarationDescriptor;
 import org.jetbrains.kotlin.descriptors.ReceiverParameterDescriptor;
 import org.jetbrains.kotlin.descriptors.annotations.Annotations;
+import org.jetbrains.kotlin.name.Name;
+import org.jetbrains.kotlin.name.SpecialNames;
 import org.jetbrains.kotlin.resolve.scopes.receivers.ReceiverValue;
 import org.jetbrains.kotlin.types.KotlinType;
 import org.jetbrains.kotlin.types.typeUtil.TypeUtilsKt;
@@ -33,7 +35,16 @@ public class ReceiverParameterDescriptorImpl extends AbstractReceiverParameterDe
             @NotNull ReceiverValue value,
             @NotNull Annotations annotations
     ) {
-        super(annotations);
+        this(containingDeclaration, value, annotations, SpecialNames.THIS);
+    }
+
+    public ReceiverParameterDescriptorImpl(
+            @NotNull DeclarationDescriptor containingDeclaration,
+            @NotNull ReceiverValue value,
+            @NotNull Annotations annotations,
+            @NotNull Name name
+    ) {
+        super(annotations, name);
         this.containingDeclaration = containingDeclaration;
         this.value = value;
     }

core/descriptors/src/org/jetbrains/kotlin/resolve/DescriptorFactory.java

@@ -22,6 +22,7 @@ import org.jetbrains.kotlin.descriptors.*;
 import org.jetbrains.kotlin.descriptors.annotations.Annotations;
 import org.jetbrains.kotlin.descriptors.impl.*;
 import org.jetbrains.kotlin.name.Name;
+import org.jetbrains.kotlin.name.NameUtils;
 import org.jetbrains.kotlin.name.StandardClassIds;
 import org.jetbrains.kotlin.resolve.scopes.receivers.ContextClassReceiver;
 import org.jetbrains.kotlin.resolve.scopes.receivers.ContextReceiver;
@@ -231,11 +232,13 @@ public class DescriptorFactory {
             @NotNull CallableDescriptor owner,
             @Nullable KotlinType receiverParameterType,
             @Nullable Name customLabelName,
-            @NotNull Annotations annotations
+            @NotNull Annotations annotations,
+            int index
     ) {
         return receiverParameterType == null
                ? null
-               : new ReceiverParameterDescriptorImpl(owner, new ContextReceiver(owner, receiverParameterType, customLabelName, null), annotations);
+               : new ReceiverParameterDescriptorImpl(owner, new ContextReceiver(owner, receiverParameterType, customLabelName, null), annotations,
+                                                     NameUtils.contextReceiverName(index));
     }
 
     @Nullable