[FIR IDE] Fix invalid reference resolve into companion with custom name

idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/references/FirReferenceResolveHelper.kt

@@ -412,10 +412,10 @@ internal object FirReferenceResolveHelper {
             var qualifiedAccess: KtDotQualifiedExpression = firSourcePsi
             val referencedClassId =
                 if ((referencedClass as? FirRegularClass)?.isCompanion == true &&
-                    (qualifiedAccess.selectorExpression as? KtNameReferenceExpression)?.getReferencedName() != "Companion"
+                    (qualifiedAccess.selectorExpression as? KtNameReferenceExpression)?.getReferencedName() != referencedClass.classId.shortClassName.asString()
                 ) {
-                    // Remove the last "Companion" part if the qualified access does not contain it. This is needed because the "Companion"
-                    // part is optional.
+                    // Remove the last companion name part if the qualified access does not contain it.
+                    // This is needed because the companion name part is optional.
                     referencedClass.classId.outerClassId ?: return referencedSymbolsByFir
                 } else {
                     referencedClass.classId

idea/idea-frontend-fir/testData/referenceResolve/nestedTypes/ResolveNamedCompanionInCompanionType.kt

@@ -0,0 +1,11 @@
+package foo.bar.baz
+
+class X {
+    companion object COMP {
+        fun lol() {}
+    }
+}
+
+class E {
+    val x = foo.bar.baz.X.CO<caret>MP
+}

idea/idea-frontend-fir/testData/referenceResolve/nestedTypes/ResolveNamedCompanionInCompanionType.txt

@@ -0,0 +1,2 @@
+Resolved to:
+0: (in foo.bar.baz.X) companion object COMP

idea/idea-frontend-fir/tests/org/jetbrains/kotlin/idea/fir/frontend/api/ReferenceResolveTestGenerated.java

@@ -971,6 +971,12 @@ public class ReferenceResolveTestGenerated extends AbstractReferenceResolveTest
             runTest("idea/idea-frontend-fir/testData/referenceResolve/nestedTypes/ResolveMiddleOfPackageInType.kt");
         }
 
+        @Test
+        @TestMetadata("ResolveNamedCompanionInCompanionType.kt")
+        public void testResolveNamedCompanionInCompanionType() throws Exception {
+            runTest("idea/idea-frontend-fir/testData/referenceResolve/nestedTypes/ResolveNamedCompanionInCompanionType.kt");
+        }
+
         @Test
         @TestMetadata("ResolveStartOfPackageInType.kt")
         public void testResolveStartOfPackageInType() throws Exception {