Support formatting of 'where' clauses

#KT-14083 Fixed

idea/formatter/src/org/jetbrains/kotlin/idea/formatter/KotlinCommonBlock.kt

@@ -263,6 +263,9 @@ abstract class KotlinCommonBlock(
                     }
                 }
 
+            parentType == KtNodeTypes.TYPE_CONSTRAINT_LIST ->
+                createAlignmentStrategy(true, getAlignment())
+
             else ->
                 getNullAlignmentStrategy()
         }
@@ -505,7 +508,12 @@ private val INDENT_RULES = arrayOf<NodeIndentStrategy>(
                         Indent.getContinuationIndent()
                     else
                         Indent.getNormalIndent()
-                })
+                },
+
+        strategy("Where clause")
+                .within(KtNodeTypes.CLASS, KtNodeTypes.FUN, KtNodeTypes.PROPERTY)
+                .forType(KtTokens.WHERE_KEYWORD)
+                .set(Indent.getContinuationIndent()))
 
 
 private fun getOperationType(node: ASTNode): IElementType? = node.findChildByType(KtNodeTypes.OPERATION_REFERENCE)?.firstChildNode?.elementType

idea/testData/formatter/WhereClause.after.kt

@@ -0,0 +1,12 @@
+abstract class RustNavigationContributorBase<T> protected constructor(
+        private val indexKey: StubIndexKey<String, T>,
+        private val clazz: Class<T>
+) : ChooseByNameContributor, GotoClassContributor
+        where T : NavigationItem,
+              T : RustNamedElement {
+}
+
+fun <T> foo()
+        where T : NavigationItem,
+              T : RustNamedElement {
+}

idea/testData/formatter/WhereClause.kt

@@ -0,0 +1,12 @@
+abstract class RustNavigationContributorBase<T> protected constructor(
+        private val indexKey: StubIndexKey<String, T>,
+        private val clazz: Class<T>
+) : ChooseByNameContributor, GotoClassContributor
+where T : NavigationItem,
+T : RustNamedElement {
+}
+
+fun <T> foo()
+where T : NavigationItem,
+T : RustNamedElement {
+}

idea/tests/org/jetbrains/kotlin/formatter/FormatterTestGenerated.java

@@ -842,6 +842,12 @@ public class FormatterTestGenerated extends AbstractFormatterTest {
             doTest(fileName);
         }
 
+        @TestMetadata("WhereClause.after.kt")
+        public void testWhereClause() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/formatter/WhereClause.after.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("WhileLineBreak.after.kt")
         public void testWhileLineBreak() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("idea/testData/formatter/WhileLineBreak.after.kt");