[postfix completion] IDEA-277334 Java 17 support: Postfix .switch doesn't work when selector expression is Object

The switch statement postfix completion template used to be applied to either elements of the Object type or of a sealed class. This restriction was just a result of a mistake. This patch lifts this restriction and makes SwitchStatementPostfixTemplate truly DumbAware by resolving an expression's type with DumbModeAccessType bypassing the dumb mode if necessary.

GitOrigin-RevId: c2f82834ff4e6842d6d825f9ff994c288196291b

java/java-impl/src/com/intellij/codeInsight/template/postfix/templates/SwitchStatementPostfixTemplate.java

@@ -20,6 +20,7 @@ import com.intellij.psi.codeStyle.CodeStyleManager;
 import com.intellij.psi.util.PsiTreeUtil;
 import com.intellij.util.Function;
 import com.intellij.util.IncorrectOperationException;
+import com.intellij.util.indexing.DumbModeAccessType;
 import org.jetbrains.annotations.Contract;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
@@ -34,12 +35,16 @@ public class SwitchStatementPostfixTemplate extends SurroundPostfixTemplateBase
   private static final Condition<PsiElement> SWITCH_TYPE = expression -> {
     if (!(expression instanceof PsiExpression)) return false;
 
-    PsiType type = ((PsiExpression)expression).getType();
+    final PsiType type = getType((PsiExpression)expression);
 
     if (type == null) return false;
     if (PsiType.INT.isAssignableFrom(type)) return true;
+    if (type instanceof PsiClassType) {
+      if (HighlightingFeature.PATTERNS_IN_SWITCH.isAvailable(expression)) return true;
 
-    if (isEnumOrObjectOrSealedClass(expression, type)) return true;
+      PsiClass psiClass = ((PsiClassType)type).resolve();
+      if (psiClass != null && psiClass.isEnum()) return true;
+    }
 
     if (type.equalsToText(CommonClassNames.JAVA_LANG_STRING)) {
       PsiFile containingFile = expression.getContainingFile();
@@ -52,6 +57,14 @@ public class SwitchStatementPostfixTemplate extends SurroundPostfixTemplateBase
     return false;
   };
 
+  @Contract(pure = true)
+  private static @Nullable PsiType getType(@NotNull PsiExpression expression) {
+    if (!DumbService.isDumb(expression.getProject())) {
+      return expression.getType();
+    }
+    return DumbModeAccessType.RELIABLE_DATA_ONLY.ignoreDumbMode(expression::getType);
+  }
+
   @Contract(pure = true)
   private static boolean isEnumOrObjectOrSealedClass(@NotNull PsiElement expression, @Nullable PsiType type) {
     if (!(type instanceof PsiClassType)) return false;

java/java-tests/testData/codeInsight/completion/normal/CompleteSwitchObjectSelectorPostfix.java

@@ -1,6 +1,6 @@
 
 class Main {
-  int g(Object o) {
+  int g(CharSequence o) {
     o.swit<caret>
   }
 }

java/java-tests/testData/codeInsight/completion/normal/CompleteSwitchObjectSelectorPostfix_after.java

@@ -1,6 +1,6 @@
 
 class Main {
-  int g(Object o) {
+  int g(CharSequence o) {
       switch (o) {
           <caret>
       }