switch expression: display dedicated error on target type void (IDEA-203776)

java/java-analysis-impl/src/com/intellij/codeInsight/daemon/impl/analysis/HighlightUtil.java

@@ -1452,6 +1452,10 @@ public class HighlightUtil extends HighlightUtilBase {
                       .create());
         }
       }
+
+      if (PsiType.VOID.equals(switchExpressionType)) {
+        infos.add(HighlightInfo.newHighlightInfo(HighlightInfoType.ERROR).range(switchExpression.getFirstChild()).descriptionAndTooltip("Target type for switch expression cannot be void").create());
+      }
     }
 
     return infos;

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/advHighlighting12/SimpleInferenceCases.java

@@ -103,5 +103,9 @@ no instance(s) of type variable(s) exist so that Integer conforms to String">()
         };
       }
     };
+
+    Runnable r = () -> <error descr="Target type for switch expression cannot be void">switch</error>(0) {
+      default -> throw new IllegalArgumentException();
+    };
   }
 }