IDEA-203447 Switch statement without default branch: support Java 12

plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/controlflow/SwitchStatementsWithoutDefaultInspection.java

@@ -17,16 +17,19 @@ package com.siyeh.ig.controlflow;
 
 import com.intellij.codeInspection.ui.SingleCheckboxOptionsPanel;
 import com.intellij.psi.*;
+import com.intellij.psi.util.PsiTreeUtil;
 import com.intellij.psi.util.PsiUtil;
 import com.siyeh.InspectionGadgetsBundle;
 import com.siyeh.ig.BaseInspection;
 import com.siyeh.ig.BaseInspectionVisitor;
-import com.siyeh.ig.psiutils.ControlFlowUtils;
 import com.siyeh.ig.psiutils.SwitchUtils;
+import one.util.streamex.StreamEx;
 import org.intellij.lang.annotations.Pattern;
 import org.jetbrains.annotations.NotNull;
 
 import javax.swing.*;
+import java.util.List;
+import java.util.Set;
 
 public class SwitchStatementsWithoutDefaultInspection extends BaseInspection {
 
@@ -72,19 +75,27 @@ public class SwitchStatementsWithoutDefaultInspection extends BaseInspection {
       if (count <= 0) {
         return;
       }
-      if (m_ignoreFullyCoveredEnums && switchStatementIsFullyCoveredEnum(statement, count)) {
+      if (m_ignoreFullyCoveredEnums && switchStatementIsFullyCoveredEnum(statement)) {
         return;
       }
       registerStatementError(statement);
     }
 
-    private boolean switchStatementIsFullyCoveredEnum(PsiSwitchStatement statement, int branchCount) {
+    private boolean switchStatementIsFullyCoveredEnum(PsiSwitchStatement statement) {
       final PsiExpression expression = statement.getExpression();
       if (expression == null) {
         return true; // don't warn on incomplete code
       }
       final PsiClass aClass = PsiUtil.resolveClassInClassTypeOnly(expression.getType());
-      return aClass != null && aClass.isEnum() && ControlFlowUtils.hasChildrenOfTypeCount(aClass, branchCount, PsiEnumConstant.class);
+      if (aClass == null || !aClass.isEnum()) return false;
+      List<PsiSwitchLabelStatementBase> labels = PsiTreeUtil.getChildrenOfTypeAsList(statement.getBody(), PsiSwitchLabelStatementBase.class);
+      Set<PsiEnumConstant> constants = StreamEx.of(labels).flatCollection(SwitchUtils::findEnumConstants).toSet();
+      for (PsiField field : aClass.getFields()) {
+        if (field instanceof PsiEnumConstant && !constants.remove(field)) {
+          return false;
+        }
+      }
+      return true;
     }
   }
 }

plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/psiutils/SwitchUtils.java

@@ -271,6 +271,35 @@ public class SwitchUtils {
     return visitor.isUsed();
   }
 
+  /**
+   * @param element a switch label element
+   * @return list of enum constants which are targets of the specified label; empty list if the supplied element is not a switch label,
+   * or it is not an enum switch.
+   */
+  @NotNull
+  public static List<PsiEnumConstant> findEnumConstants(PsiElement element) {
+    if (!(element instanceof PsiSwitchLabelStatementBase)) {
+      return Collections.emptyList();
+    }
+    final PsiSwitchLabelStatementBase switchLabelStatement = (PsiSwitchLabelStatementBase)element;
+    final PsiExpressionList list = switchLabelStatement.getCaseValues();
+    if (list == null) {
+      return Collections.emptyList();
+    }
+    List<PsiEnumConstant> constants = new ArrayList<>();
+    for (PsiExpression value : list.getExpressions()) {
+      if (value instanceof PsiReferenceExpression) {
+        final PsiElement target = ((PsiReferenceExpression)value).resolve();
+        if (target instanceof PsiEnumConstant) {
+          constants.add((PsiEnumConstant)target);
+          continue;
+        }
+      }
+      return Collections.emptyList();
+    }
+    return constants;
+  }
+
   private static class LabelSearchVisitor extends JavaRecursiveElementWalkingVisitor {
 
     private final String m_labelName;

plugins/InspectionGadgets/test/com/siyeh/igtest/controlflow/switch_statements_without_default/SwitchStatementsWithoutDefault.java

@@ -81,6 +81,23 @@ public class SwitchStatementsWithoutDefault
                 break;
         }
     }
+    
+    public void testRules(T t, MyEnum my) {
+        switch (t) {
+            case A -> {}
+            case B -> {}
+        }
+        switch (t) {
+            case A, B -> {}
+        }
+        <warning descr="'switch' statement without 'default' branch">switch</warning> (my) {
+            case foo, bar -> {}
+        }
+        switch (my) {
+            case foo, bar -> {}
+            case baz -> {}
+        }
+    }
 
     void empty(T t) {
         switch (t) {

plugins/InspectionGadgets/testsrc/com/siyeh/ig/controlflow/SwitchStatementsWithoutDefaultInspectionTest.java

@@ -16,7 +16,9 @@
 package com.siyeh.ig.controlflow;
 
 import com.intellij.codeInspection.InspectionProfileEntry;
+import com.intellij.testFramework.LightProjectDescriptor;
 import com.siyeh.ig.LightInspectionTestCase;
+import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
 public class SwitchStatementsWithoutDefaultInspectionTest extends LightInspectionTestCase {
@@ -25,6 +27,12 @@ public class SwitchStatementsWithoutDefaultInspectionTest extends LightInspectio
     doTest();
   }
 
+  @NotNull
+  @Override
+  protected LightProjectDescriptor getProjectDescriptor() {
+    return JAVA_12;
+  }
+
   @Nullable
   @Override
   protected InspectionProfileEntry getInspection() {