Implicit exhaustive when annotation / highlighting

idea/idea-analysis/src/org/jetbrains/kotlin/idea/KotlinBundle.properties

@@ -135,6 +135,7 @@ options.kotlin.attribute.descriptor.variable.as.function.like.call=Variable as f
 options.kotlin.attribute.descriptor.smart.cast=Smart-cast value
 options.kotlin.attribute.descriptor.smart.constant=Smart constant
 options.kotlin.attribute.descriptor.smart.cast.receiver=Smart-cast implicit receiver
+options.kotlin.attribute.descriptor.implicit.exhaustive.when=Implicitly exhaustive when
 options.kotlin.attribute.descriptor.label=Label
 change.to.function.invocation=Change to function invocation
 migrate.sure=Replace sure() calls by !! in project

idea/idea-analysis/src/org/jetbrains/kotlin/idea/highlighter/KotlinHighlightingColors.java

@@ -85,6 +85,7 @@ public class KotlinHighlightingColors {
     public static final TextAttributesKey SMART_CAST_VALUE = createTextAttributesKey("KOTLIN_SMART_CAST_VALUE");
     public static final TextAttributesKey SMART_CONSTANT = createTextAttributesKey("KOTLIN_SMART_CONSTANT");
     public static final TextAttributesKey SMART_CAST_RECEIVER = createTextAttributesKey("KOTLIN_SMART_CAST_RECEIVER");
+    public static final TextAttributesKey IMPLICIT_EXHAUSTIVE_WHEN = createTextAttributesKey("KOTLIN_IMPLICIT_EXHAUSTIVE_WHEN");
     public static final TextAttributesKey LABEL = createTextAttributesKey("KOTLIN_LABEL");
     public static final TextAttributesKey DEBUG_INFO = createTextAttributesKey("KOTLIN_DEBUG_INFO");
     public static final TextAttributesKey RESOLVED_TO_ERROR = createTextAttributesKey("KOTLIN_RESOLVED_TO_ERROR");

idea/idea-analysis/src/org/jetbrains/kotlin/idea/highlighter/VariablesHighlightingVisitor.java

@@ -110,6 +110,15 @@ class VariablesHighlightingVisitor extends AfterAnalysisHighlightingVisitor {
                   .setTextAttributes(KotlinHighlightingColors.SMART_CAST_VALUE);
         }
 
+        if (expression instanceof KtWhenExpression) {
+            KtWhenExpression whenExpression = (KtWhenExpression) expression;
+            boolean implicitExhaustiveWhen = bindingContext.get(IMPLICIT_EXHAUSTIVE_WHEN, whenExpression) == Boolean.TRUE;
+            if (implicitExhaustiveWhen) {
+                holder.createInfoAnnotation(whenExpression.getWhenKeyword(), "When is implicitly exhaustive")
+                      .setTextAttributes(KotlinHighlightingColors.IMPLICIT_EXHAUSTIVE_WHEN);
+            }
+        }
+
         super.visitExpression(expression);
     }
 

idea/resources/colorScheme/Darcula_Kotlin.xml

@@ -40,6 +40,11 @@
       <option name="BACKGROUND" value="223c23" />
     </value>
   </option>
+  <option name="KOTLIN_IMPLICIT_EXHAUSTIVE_WHEN">
+    <value>
+      <option name="BACKGROUND" value="0321ab" />
+    </value>
+  </option>
   <option name="KOTLIN_LABEL">
     <value>
       <option name="FOREGROUND" value="467cda" />

idea/resources/colorScheme/Default_Kotlin.xml

@@ -40,6 +40,11 @@
       <option name="BACKGROUND" value="dbffdb" />
     </value>
   </option>
+  <option name="KOTLIN_IMPLICIT_EXHAUSTIVE_WHEN">
+    <value>
+      <option name="BACKGROUND" value="d3faf8" />
+    </value>
+  </option>
   <option name="KOTLIN_LABEL">
     <value>
       <option name="FOREGROUND" value="4a86e8" />

idea/src/org/jetbrains/kotlin/idea/highlighter/KotlinColorSettingsPage.kt

@@ -63,13 +63,17 @@ public class KotlinColorSettingsPage : ColorSettingsPage {
     }
 }
 
-fun Int?.bar() {
+fun Int?.bar(): Int {
     if (this != null) {
         println(<SMART_CAST_RECEIVER>toString</SMART_CAST_RECEIVER>())
     }
     else {
         println(<SMART_CONSTANT>this</SMART_CONSTANT>.toString())
     }
+    <IMPLICIT_EXHAUSTIVE_WHEN>when</IMPLICIT_EXHAUSTIVE_WHEN> (this != null) {
+        true -> return 1
+        false -> return 0
+    }
 }
 
 var <PROPERTY_WITH_BACKING_FIELD><PACKAGE_PROPERTY><MUTABLE_VARIABLE>globalCounter</MUTABLE_VARIABLE></PACKAGE_PROPERTY></PROPERTY_WITH_BACKING_FIELD> : Int = 5
@@ -157,6 +161,7 @@ var <PROPERTY_WITH_BACKING_FIELD><PACKAGE_PROPERTY><MUTABLE_VARIABLE>globalCount
                        KotlinBundle.message("options.kotlin.attribute.descriptor.smart.cast") to KotlinHighlightingColors.SMART_CAST_VALUE,
                        KotlinBundle.message("options.kotlin.attribute.descriptor.smart.constant") to KotlinHighlightingColors.SMART_CONSTANT,
                        KotlinBundle.message("options.kotlin.attribute.descriptor.smart.cast.receiver") to KotlinHighlightingColors.SMART_CAST_RECEIVER,
+                       KotlinBundle.message("options.kotlin.attribute.descriptor.implicit.exhaustive.when") to KotlinHighlightingColors.IMPLICIT_EXHAUSTIVE_WHEN,
                        KotlinBundle.message("options.kotlin.attribute.descriptor.label") to KotlinHighlightingColors.LABEL)
     }
 

idea/testData/checker/infos/WhenImplicitExhaustive.kt

@@ -0,0 +1,6 @@
+fun foo(b: Boolean): Int {
+    <info descr="When is implicitly exhaustive">when</info> (b) {
+        true -> return 1
+        false -> return 0
+    }
+}

idea/tests/org/jetbrains/kotlin/checkers/PsiCheckerTestGenerated.java

@@ -766,6 +766,12 @@ public class PsiCheckerTestGenerated extends AbstractPsiCheckerTest {
             doTestWithInfos(fileName);
         }
 
+        @TestMetadata("WhenImplicitExhaustive.kt")
+        public void testWhenImplicitExhaustive() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/checker/infos/WhenImplicitExhaustive.kt");
+            doTestWithInfos(fileName);
+        }
+
         @TestMetadata("WrapIntoRef.kt")
         public void testWrapIntoRef() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("idea/testData/checker/infos/WrapIntoRef.kt");