FIR checker: introduce FunctionChecker alias

and use it to add support diagnostic FUNCTION_DECLARATION_WITH_NO_NAME

compiler/testData/diagnostics/tests/declarationChecks/FunctionWithMissingNames.fir.kt

@@ -3,18 +3,18 @@ annotation class a
 interface A
 interface B
 
-fun () {}
-fun A.() {}
+<!FUNCTION_DECLARATION_WITH_NO_NAME!>fun ()<!> {}
+<!FUNCTION_DECLARATION_WITH_NO_NAME!>fun A.()<!> {}
 
-@a fun () {}
-fun @a A.() {}
+<!FUNCTION_DECLARATION_WITH_NO_NAME!>@a fun ()<!> {}
+<!FUNCTION_DECLARATION_WITH_NO_NAME!>fun @a A.()<!> {}
 
 class Outer {
-    fun () {}
-    fun B.() {}
+    <!FUNCTION_DECLARATION_WITH_NO_NAME!>fun ()<!> {}
+    <!FUNCTION_DECLARATION_WITH_NO_NAME!>fun B.()<!> {}
 
-    @a fun () {}
-    fun @a A.() {}
+    <!FUNCTION_DECLARATION_WITH_NO_NAME!>@a fun ()<!> {}
+    <!FUNCTION_DECLARATION_WITH_NO_NAME!>fun @a A.()<!> {}
 }
 
 fun outerFun() {

compiler/testData/diagnostics/tests/duplicateJvmSignature/missingNames.fir.kt

@@ -1,9 +1,9 @@
 // !DIAGNOSTICS: -DUPLICATE_CLASS_NAMES
-fun () {
+<!FUNCTION_DECLARATION_WITH_NO_NAME!>fun ()<!> {
 
 }
 
-fun Outer.() {
+<!FUNCTION_DECLARATION_WITH_NO_NAME!>fun Outer.()<!> {
 
 }
 
@@ -30,7 +30,7 @@ annotation class<!SYNTAX!><!> {
 }
 
 class Outer {
-    fun () {
+    <!FUNCTION_DECLARATION_WITH_NO_NAME!>fun ()<!> {
 
     }
 

compiler/testData/diagnostics/tests/recovery/namelessInJava.fir.kt

@@ -1,18 +0,0 @@
-// SKIP_JAVAC
-// FILE: p/Nameless.java
-
-package p;
-
-public class Nameless {
-    void () {}
-    int ;
-}
-
-// FILE: k.kt
-
-import p.*
-
-class K : Nameless() {
-    fun () {}
-    val<!SYNTAX!><!> : Int = 1
-}

compiler/testData/diagnostics/tests/recovery/namelessInJava.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 // SKIP_JAVAC
 // FILE: p/Nameless.java
 

compiler/testData/diagnostics/tests/recovery/namelessMembers.fir.kt

@@ -1,17 +0,0 @@
-// !DIAGNOSTICS: -REDECLARATION -DUPLICATE_CLASS_NAMES
-
-class C {
-    fun () {
-
-    }
-
-    val<!SYNTAX!><!> : Int = 1
-
-    class<!SYNTAX!><!> {}
-
-    enum class<!SYNTAX!><!> {}
-}
-
-class C1<<!SYNTAX!>in<!>> {}
-
-class C2(val<!SYNTAX!><!>) {}

compiler/testData/diagnostics/tests/recovery/namelessMembers.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 // !DIAGNOSTICS: -REDECLARATION -DUPLICATE_CLASS_NAMES
 
 class C {

compiler/testData/diagnostics/tests/recovery/namelessToplevelDeclarations.fir.kt

@@ -2,7 +2,7 @@
 
 package<!SYNTAX!><!>
 
-fun () {
+<!FUNCTION_DECLARATION_WITH_NO_NAME!>fun ()<!> {
 
 }