Don't report "main parameter not necessary" in objects #KT-29414 Fixed

compiler/frontend/src/org/jetbrains/kotlin/cfg/ControlFlowInformationProvider.kt

@@ -31,6 +31,7 @@ import org.jetbrains.kotlin.diagnostics.Errors.*
 import org.jetbrains.kotlin.idea.MainFunctionDetector
 import org.jetbrains.kotlin.lexer.KtTokens
 import org.jetbrains.kotlin.psi.*
+import org.jetbrains.kotlin.psi.psiUtil.containingClassOrObject
 import org.jetbrains.kotlin.resolve.*
 import org.jetbrains.kotlin.resolve.BindingContext.*
 import org.jetbrains.kotlin.resolve.bindingContextUtil.isUsedAsExpression
@@ -736,7 +737,9 @@ class ControlFlowInformationProvider private constructor(
                             return
                         }
                         !languageVersionSettings.supportsFeature(LanguageFeature.WarningOnMainUnusedParameter) -> {
-                            trace.record(UNUSED_MAIN_PARAMETER, element)
+                            if (owner.containingClassOrObject == null) {
+                                trace.record(UNUSED_MAIN_PARAMETER, element)
+                            }
                             return
                         }
                     }

idea/testData/inspectionsLocal/unusedMainParameter/object.kt

@@ -0,0 +1,7 @@
+// LANGUAGE_VERSION: 1.3
+// WITH_RUNTIME
+// PROBLEM: none
+
+object SomeMain {
+    @JvmStatic fun main(<caret>args: Array<String>) {}
+}

idea/tests/org/jetbrains/kotlin/idea/inspections/LocalInspectionTestGenerated.java

@@ -8136,6 +8136,11 @@ public class LocalInspectionTestGenerated extends AbstractLocalInspectionTest {
             runTest("idea/testData/inspectionsLocal/unusedMainParameter/legacy.kt");
         }
 
+        @TestMetadata("object.kt")
+        public void testObject() throws Exception {
+            runTest("idea/testData/inspectionsLocal/unusedMainParameter/object.kt");
+        }
+
         @TestMetadata("simple.kt")
         public void testSimple() throws Exception {
             runTest("idea/testData/inspectionsLocal/unusedMainParameter/simple.kt");