KT-2752: fix name clash diagnostic for case of extension property. Add more tests for the diagnostic

js/js.frontend/src/org/jetbrains/kotlin/js/naming/FQNGenerator.kt

@@ -61,7 +61,12 @@ class FQNGenerator {
         }
 
         val (localName, shared, parent) = getLocalName(descriptor)
-        return FQNPart(listOf(localName), shared, descriptor, parent)
+        return FQNPart(listOf(localName), shared, descriptor, fixParent(parent))
+    }
+
+    private fun fixParent(parent: DeclarationDescriptor) = when (parent) {
+        is PropertyDescriptor -> parent.containingDeclaration
+        else -> parent
     }
 
     private fun getLocalName(descriptor: DeclarationDescriptor): LocalName {

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

@@ -22,9 +22,11 @@ import org.jetbrains.kotlin.diagnostics.DiagnosticSink
 import org.jetbrains.kotlin.js.naming.FQNGenerator
 import org.jetbrains.kotlin.js.translate.utils.AnnotationsUtils
 import org.jetbrains.kotlin.psi.KtDeclaration
+import org.jetbrains.kotlin.psi.KtProperty
 import org.jetbrains.kotlin.resolve.BindingContext
 import org.jetbrains.kotlin.resolve.DeclarationChecker
 import org.jetbrains.kotlin.resolve.DescriptorUtils
+import org.jetbrains.kotlin.resolve.descriptorUtil.isExtension
 import org.jetbrains.kotlin.resolve.scopes.MemberScope
 import org.jetbrains.kotlin.resolve.source.getPsi
 
@@ -39,7 +41,9 @@ class JsNameChecker : DeclarationChecker {
             diagnosticHolder: DiagnosticSink,
             bindingContext: BindingContext
     ) {
-        checkDescriptor(descriptor, declaration, diagnosticHolder)
+        if (declaration !is KtProperty || !descriptor.isExtension) {
+            checkDescriptor(descriptor, declaration, diagnosticHolder)
+        }
     }
 
     private fun checkDescriptor(descriptor: DeclarationDescriptor, declaration: KtDeclaration, diagnosticHolder: DiagnosticSink) {
@@ -87,6 +91,15 @@ class JsNameChecker : DeclarationChecker {
 
     private fun collect(scope: MemberScope, target: MutableMap<String, DeclarationDescriptor>) {
         for (descriptor in scope.getContributedDescriptors()) {
+            collect(descriptor, target)
+        }
+    }
+
+    private fun collect(descriptor: DeclarationDescriptor, target: MutableMap<String, DeclarationDescriptor>) {
+        if (descriptor is PropertyDescriptor && descriptor.isExtension) {
+            descriptor.accessors.forEach { collect(it, target) }
+        }
+        else {
             val fqn = fqnGenerator.generate(descriptor)
             if (fqn.shared && isOpaque(fqn.descriptor)) {
                 target[fqn.names.last()] = fqn.descriptor
@@ -94,13 +107,6 @@ class JsNameChecker : DeclarationChecker {
         }
     }
 
-    private fun collect(descriptor: DeclarationDescriptor, target: MutableMap<String, DeclarationDescriptor>) {
-        val fqn = fqnGenerator.generate(descriptor)
-        if (fqn.shared && isOpaque(fqn.descriptor)) {
-            target[fqn.names.last()] = fqn.descriptor
-        }
-    }
-
     private fun isOpaque(descriptor: DeclarationDescriptor) =
             !AnnotationsUtils.isNativeObject(descriptor) && !AnnotationsUtils.isLibraryObject(descriptor)
 }