Report initializer block-related diagnostic on 'init' keyword

compiler/frontend/src/org/jetbrains/kotlin/diagnostics/Errors.java

@@ -810,7 +810,7 @@ public interface Errors {
     DiagnosticFactory0<KtDeclarationWithBody>
             NO_RETURN_IN_FUNCTION_WITH_BLOCK_BODY = DiagnosticFactory0.create(ERROR, DECLARATION_WITH_BODY);
 
-    DiagnosticFactory0<KtAnonymousInitializer> ANONYMOUS_INITIALIZER_IN_INTERFACE = DiagnosticFactory0.create(ERROR);
+    DiagnosticFactory0<KtAnonymousInitializer> ANONYMOUS_INITIALIZER_IN_INTERFACE = DiagnosticFactory0.create(ERROR, DECLARATION_SIGNATURE);
 
     DiagnosticFactory0<KtThisExpression> NO_THIS = DiagnosticFactory0.create(ERROR);
     DiagnosticFactory1<KtSimpleNameExpression, ClassifierDescriptor> NO_COMPANION_OBJECT = DiagnosticFactory1.create(ERROR);

compiler/frontend/src/org/jetbrains/kotlin/diagnostics/PositioningStrategies.kt

@@ -160,6 +160,9 @@ object PositioningStrategies {
                 is KtObjectDeclaration -> {
                     return DECLARATION_NAME.mark(element)
                 }
+                is KtClassInitializer -> {
+                    return markRange(element.initKeyword.textRange)
+                }
             }
             return super.mark(element)
         }

compiler/frontend/src/org/jetbrains/kotlin/psi/KtAnonymousInitializer.kt

@@ -18,6 +18,7 @@ package org.jetbrains.kotlin.psi
 
 import com.intellij.lang.ASTNode
 import com.intellij.psi.PsiElement
+import org.jetbrains.kotlin.lexer.KtTokens
 import org.jetbrains.kotlin.psi.psiUtil.getParentOfType
 import org.jetbrains.kotlin.psi.stubs.KotlinPlaceHolderStub
 import org.jetbrains.kotlin.psi.stubs.elements.KtStubElementTypes
@@ -41,6 +42,9 @@ class KtClassInitializer : KtDeclarationStub<KotlinPlaceHolderStub<KtClassInitia
     val openBraceNode: PsiElement?
         get() = (body as? KtBlockExpression)?.lBrace
 
+    val initKeyword: PsiElement
+        get() = findChildByType(KtTokens.INIT_KEYWORD)!!
+
     override val containingDeclaration: KtDeclaration
         get() = getParentOfType<KtClassOrObject>(true).sure { "Should only be present in class or object" }
 }

compiler/testData/diagnostics/tests/AnonymousInitializers.kt

@@ -1,13 +1,13 @@
 interface NoC {
-  <!ANONYMOUS_INITIALIZER_IN_INTERFACE!>init {
+  <!ANONYMOUS_INITIALIZER_IN_INTERFACE!>init<!> {
 
-  }<!>
+  }
 
   val a : Int get() = 1
 
-  <!ANONYMOUS_INITIALIZER_IN_INTERFACE!>init {
+  <!ANONYMOUS_INITIALIZER_IN_INTERFACE!>init<!> {
 
-  }<!>
+  }
 }
 
 class WithC() {
@@ -23,4 +23,4 @@ class WithC() {
     val <!UNUSED_VARIABLE!>z<!> = <!UNRESOLVED_REFERENCE!>b<!>
     val <!UNUSED_VARIABLE!>zz<!> = x
   }
-}
+}

compiler/testData/diagnostics/tests/annotations/onInitializer.kt

@@ -4,8 +4,8 @@ class A {
 }
 
 interface T {
-    <!ANONYMOUS_INITIALIZER_IN_INTERFACE!><!WRONG_ANNOTATION_TARGET!>@ann<!> init {}<!>
-    <!ANONYMOUS_INITIALIZER_IN_INTERFACE!><!WRONG_ANNOTATION_TARGET!>@<!UNRESOLVED_REFERENCE!>aaa<!><!> init {}<!>
+    <!WRONG_ANNOTATION_TARGET!>@ann<!> <!ANONYMOUS_INITIALIZER_IN_INTERFACE!>init<!> {}
+    <!WRONG_ANNOTATION_TARGET!>@<!UNRESOLVED_REFERENCE!>aaa<!><!> <!ANONYMOUS_INITIALIZER_IN_INTERFACE!>init<!> {}
 }
 
-annotation class ann
+annotation class ann

idea/testData/checker/AnonymousInitializers.kt

@@ -1,13 +1,13 @@
 interface NoC {
-  <error>init {
+  <error>init</error> {
 
-  }</error>
+  }
 
   val a : Int get() = 1
 
-  <error>init {
+  <error>init</error> {
 
-  }</error>
+  }
 }
 
 class WithC() {
@@ -24,4 +24,4 @@ class WithC() {
     val <warning>zz</warning> = x
   }
 
-}
+}

idea/testData/checker/regression/InitializerInInterface.kt

@@ -1,6 +1,6 @@
 interface I {
-    <error>init {
+    <error>init</error> {
         val c = 1
-        val g = c
-    }</error>
-}
+        val <warning>g</warning> = c
+    }
+}