KT-2752: remove diagnostic that reports about overridden method having several names from different sources. Generate proxies instead. Fix reporting name clash when two distinct fake overrides require same name.

js/js.frontend/src/org/jetbrains/kotlin/js/resolve/diagnostics/DefaultErrorMessagesJs.kt

@@ -45,8 +45,6 @@ private val DIAGNOSTIC_FACTORY_TO_RENDERER by lazy {
         put(ErrorsJs.JS_NAME_ON_ACCESSOR_AND_PROPERTY, "@JsName can be either on a property or its accessors, not both of them")
         put(ErrorsJs.JS_NAME_IS_NOT_ON_ALL_ACCESSORS, "@JsName should be on all of the property accessors")
         put(ErrorsJs.JS_NAME_PROHIBITED_FOR_OVERRIDE, "@JsName is prohibited for overridden members")
-        put(ErrorsJs.JS_NAME_OVERRIDE_CLASH, "Conflicting names got from overridden declarations {0} and {1}", Renderers.COMPACT,
-            Renderers.COMPACT)
 
         this
     }

js/js.frontend/src/org/jetbrains/kotlin/js/resolve/diagnostics/ErrorsJs.java

@@ -49,7 +49,6 @@ public interface ErrorsJs {
     DiagnosticFactory0<KtElement> JS_NAME_ON_ACCESSOR_AND_PROPERTY = DiagnosticFactory0.create(ERROR);
     DiagnosticFactory0<PsiElement> JS_NAME_IS_NOT_ON_ALL_ACCESSORS = DiagnosticFactory0.create(ERROR);
     DiagnosticFactory0<PsiElement> JS_NAME_PROHIBITED_FOR_OVERRIDE = DiagnosticFactory0.create(ERROR);
-    DiagnosticFactory2<PsiElement, DeclarationDescriptor, DeclarationDescriptor> JS_NAME_OVERRIDE_CLASH = DiagnosticFactory2.create(ERROR);
 
     @SuppressWarnings("UnusedDeclaration")
     Object _initializer = new Object() {

js/js.frontend/src/org/jetbrains/kotlin/js/resolve/diagnostics/JsNameClashChecker.kt

@@ -33,6 +33,7 @@ import org.jetbrains.kotlin.resolve.scopes.MemberScope
 class JsNameClashChecker : SimpleDeclarationChecker {
     private val fqnGenerator = FQNGenerator()
     private val scopes = mutableMapOf<DeclarationDescriptor, MutableMap<String, DeclarationDescriptor>>()
+    private val clashedFakeOverrides = mutableMapOf<DeclarationDescriptor, Pair<DeclarationDescriptor, DeclarationDescriptor>>()
     private val clashedDescriptors = mutableSetOf<DeclarationDescriptor>()
 
     override fun check(
@@ -74,6 +75,14 @@ class JsNameClashChecker : SimpleDeclarationChecker {
                 val existing = scope[name]
                 if (existing != null && existing != overrideFqn.descriptor) {
                     diagnosticHolder.report(ErrorsJs.JS_NAME_CLASH_SYNTHETIC.on(declaration, name, override, existing))
+                    break
+                }
+
+                val clashedOverrides = clashedFakeOverrides[override]
+                if (clashedOverrides != null) {
+                    val (firstExample, secondExample) = clashedOverrides
+                    diagnosticHolder.report(ErrorsJs.JS_NAME_CLASH_SYNTHETIC.on(declaration, name, firstExample, secondExample))
+                    break
                 }
             }
         }
@@ -111,6 +120,28 @@ class JsNameClashChecker : SimpleDeclarationChecker {
         val fqn = fqnGenerator.generate(descriptor)
         if (fqn.shared && isOpaque(fqn.descriptor)) {
             target[fqn.names.last()] = fqn.descriptor
+            (fqn.descriptor as? CallableMemberDescriptor)?.let { checkOverrideClashes(it, target) }
+        }
+    }
+
+    private fun checkOverrideClashes(descriptor: CallableMemberDescriptor, target: MutableMap<String, DeclarationDescriptor>) {
+        var overridden = descriptor.overriddenDescriptors
+        while (overridden.isNotEmpty()) {
+            for (overridenDescriptor in overridden) {
+                val overriddenFqn = fqnGenerator.generate(overridenDescriptor)
+                if (overriddenFqn.shared) {
+                    val existing = target[overriddenFqn.names.last()]
+                    if (existing != null) {
+                        if (existing != descriptor && descriptor.kind == CallableMemberDescriptor.Kind.FAKE_OVERRIDE) {
+                            clashedFakeOverrides[descriptor] = Pair(existing, overridenDescriptor)
+                        }
+                    }
+                    else {
+                        target[overriddenFqn.names.last()] = descriptor
+                    }
+                }
+            }
+            overridden = overridden.flatMap { it.overriddenDescriptors }
         }
     }
 

js/js.frontend/src/org/jetbrains/kotlin/js/resolve/diagnostics/OverriddenJsNameChecker.kt

@@ -16,7 +16,6 @@
 
 package org.jetbrains.kotlin.js.resolve.diagnostics
 
-import org.jetbrains.kotlin.config.LanguageFeatureSettings
 import org.jetbrains.kotlin.descriptors.CallableMemberDescriptor
 import org.jetbrains.kotlin.descriptors.ClassDescriptor
 import org.jetbrains.kotlin.descriptors.DeclarationDescriptor
@@ -31,7 +30,7 @@ class OverriddenJsNameChecker : DeclarationChecker {
     private val fqnGenerator = FQNGenerator()
 
     override fun check(declaration: KtDeclaration, descriptor: DeclarationDescriptor, diagnosticHolder: DiagnosticSink,
-                       bindingContext: BindingContext, languageFeatureSettings: LanguageFeatureSettings) {
+                       bindingContext: BindingContext) {
         doCheck(descriptor) { first, second ->
             val psi = descriptor.findPsi() ?: declaration
             diagnosticHolder.report(ErrorsJs.JS_NAME_OVERRIDE_CLASH.on(psi, first, second))