Minor: cover negative cases with test +m

Add case without reported diagnostic on public companion.
Only report diagnostic if @JvmStatic annotation has source in code.

KT-25114

compiler/frontend.java/src/org/jetbrains/kotlin/resolve/jvm/checkers/JvmStaticInPrivateCompanionChecker.kt

@@ -18,14 +18,16 @@ import org.jetbrains.kotlin.utils.addToStdlib.safeAs
 
 class JvmStaticInPrivateCompanionChecker : DeclarationChecker {
     override fun check(declaration: KtDeclaration, descriptor: DeclarationDescriptor, context: DeclarationCheckerContext) {
+        val containingDeclaration = descriptor.containingDeclaration
 
-        descriptor.containingDeclaration.safeAs<ClassDescriptor>()?.takeIf {
+        if (containingDeclaration !is ClassDescriptor
-            it.isCompanionObject && Visibilities.isPrivate(it.visibility.delegate)
+            || !containingDeclaration.isCompanionObject
-        } ?: return
+            || !Visibilities.isPrivate(containingDeclaration.visibility.delegate)
+        ) return
 
         val jvmStaticAnnotation = descriptor.annotations.findAnnotation(JVM_STATIC_ANNOTATION_FQ_NAME) ?: return
 
-        val reportTarget = jvmStaticAnnotation.source.safeAs<KotlinSourceElement>()?.psi ?: declaration
+        val reportTarget = jvmStaticAnnotation.source.safeAs<KotlinSourceElement>()?.psi ?: return
         context.trace.report(JVM_STATIC_IN_PRIVATE_COMPANION.on(reportTarget))
     }
 }

compiler/testData/diagnostics/testsWithStdLib/annotations/jvmStatic/privateCompanionObject.fir.kt

@@ -27,3 +27,30 @@ class WithPrivateCompanion {
         fun staticFunction() {}
     }
 }
+
+class WithPublicCompanion {
+    companion object {
+        @JvmStatic
+        val staticVal1: Int = 42
+
+        val staticVal2: Int
+            @JvmStatic get() = 42
+
+        @get:JvmStatic
+        val staticVal3: Int = 42
+
+        @JvmStatic
+        var staticVar1: Int = 42
+
+        var staticVar2: Int
+            @JvmStatic get() = 42
+            @JvmStatic set(value) {}
+
+        @get: JvmStatic
+        @set: JvmStatic
+        var staticVar3: Int = 42
+
+        @JvmStatic
+        fun staticFunction() {}
+    }
+}

compiler/testData/diagnostics/testsWithStdLib/annotations/jvmStatic/privateCompanionObject.kt

@@ -27,3 +27,30 @@ class WithPrivateCompanion {
         fun staticFunction() {}
     }
 }
+
+class WithPublicCompanion {
+    companion object {
+        @JvmStatic
+        val staticVal1: Int = 42
+
+        val staticVal2: Int
+            @JvmStatic get() = 42
+
+        @get:JvmStatic
+        val staticVal3: Int = 42
+
+        @JvmStatic
+        var staticVar1: Int = 42
+
+        var staticVar2: Int
+            @JvmStatic get() = 42
+            @JvmStatic set(value) {}
+
+        @get: JvmStatic
+        @set: JvmStatic
+        var staticVar3: Int = 42
+
+        @JvmStatic
+        fun staticFunction() {}
+    }
+}

compiler/testData/diagnostics/testsWithStdLib/annotations/jvmStatic/privateCompanionObject.txt

@@ -20,3 +20,24 @@ public final class WithPrivateCompanion {
         public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
     }
 }
+
+public final class WithPublicCompanion {
+    public constructor WithPublicCompanion()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+
+    public companion object Companion {
+        private constructor Companion()
+        @kotlin.jvm.JvmStatic public final val staticVal1: kotlin.Int = 42
+        @get:kotlin.jvm.JvmStatic public final val staticVal2: kotlin.Int
+        @get:kotlin.jvm.JvmStatic public final val staticVal3: kotlin.Int = 42
+        @kotlin.jvm.JvmStatic public final var staticVar1: kotlin.Int
+        @get:kotlin.jvm.JvmStatic @set:kotlin.jvm.JvmStatic public final var staticVar2: kotlin.Int
+        @get:kotlin.jvm.JvmStatic @set:kotlin.jvm.JvmStatic public final var staticVar3: kotlin.Int
+        public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+        public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+        @kotlin.jvm.JvmStatic public final fun staticFunction(): kotlin.Unit
+        public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+    }
+}