Added optimized PackageFragmentProvider#isEmpty(FqName)

compiler/frontend.java/src/org/jetbrains/kotlin/load/kotlin/incremental/IncrementalPackageFragmentProvider.kt

@@ -60,6 +60,8 @@ class IncrementalPackageFragmentProvider(
     override fun collectPackageFragments(fqName: FqName, packageFragments: MutableCollection<PackageFragmentDescriptor>) =
         packageFragments.addIfNotNull(fqNameToPackageFragment[fqName])
 
+    override fun isEmpty(fqName: FqName): Boolean = !fqNameToPackageFragment.containsKey(fqName)
+
     override fun getPackageFragments(fqName: FqName): List<PackageFragmentDescriptor> {
         return listOfNotNull(fqNameToPackageFragment[fqName])
     }

compiler/frontend.java/src/org/jetbrains/kotlin/resolve/jvm/multiplatform/OptionalAnnotationPackageFragmentProvider.kt

@@ -83,6 +83,9 @@ class OptionalAnnotationPackageFragmentProvider(
     override fun collectPackageFragments(fqName: FqName, packageFragments: MutableCollection<PackageFragmentDescriptor>) =
         packageFragments.addIfNotNull(packages[fqName])
 
+    override fun isEmpty(fqName: FqName): Boolean =
+        !packages.containsKey(fqName)
+
     override fun getPackageFragments(fqName: FqName): List<PackageFragmentDescriptor> =
         packages[fqName]?.let(::listOf).orEmpty()
 

compiler/frontend/src/org/jetbrains/kotlin/analyzer/AbstractResolverForProject.kt

@@ -252,6 +252,12 @@ private class DelegatingPackageFragmentProvider<M : ModuleInfo>(
         resolverForProject.resolverForModuleDescriptor(module).packageFragmentProvider.collectPackageFragmentsOptimizedIfPossible(fqName, packageFragments)
     }
 
+    override fun isEmpty(fqName: FqName): Boolean {
+        if (certainlyDoesNotExist(fqName)) return true
+
+        return resolverForProject.resolverForModuleDescriptor(module).packageFragmentProvider.isEmpty(fqName)
+    }
+
     override fun getSubPackagesOf(fqName: FqName, nameFilter: (Name) -> Boolean): Collection<FqName> {
         if (certainlyDoesNotExist(fqName)) return emptyList()
 

compiler/frontend/src/org/jetbrains/kotlin/resolve/lazy/ResolveSession.java

@@ -204,6 +204,12 @@ public class ResolveSession implements KotlinCodeAnalyzer, LazyClassContext {
                 }
             }
 
+            @Override
+            public boolean isEmpty(@NotNull FqName fqName) {
+                PackageMemberDeclarationProvider provider = declarationProviderFactory.getPackageMemberDeclarationProvider(fqName);
+                return provider == null;
+            }
+
             @NotNull
             @Override
             public List<PackageFragmentDescriptor> getPackageFragments(@NotNull FqName fqName) {