8311825: Duplicate qualified enum constants not detected

Reviewed-by: vromero
Backport-of: d1fa1a868636dc15e96d1b4bf4acf28257c9551f

Author: lahodaj

src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Attr.java

@@ -1734,6 +1734,8 @@ private void handleSwitch(JCTree switchTree,
                                     Symbol enumSym = TreeInfo.symbol(expr);
                                     if (enumSym == null || !enumSym.isEnum() || enumSym.kind != VAR) {
                                         log.error(expr.pos(), Errors.EnumLabelMustBeEnumConstant);
+                                    } else if (!constants.add(enumSym)) {
+                                        log.error(label.pos(), Errors.DuplicateCaseLabel);
                                     }
                                 } else {
                                     log.error(expr.pos(), Errors.EnumLabelMustBeUnqualifiedEnum);
@@ -1765,6 +1767,8 @@ private void handleSwitch(JCTree switchTree,
                                                   (stringSwitch ? Errors.StringConstReq
                                                                 : intSwitch ? Errors.ConstExprReq
                                                                             : Errors.PatternOrEnumReq));
+                                    } else if (!constants.add(s)) {
+                                        log.error(label.pos(), Errors.DuplicateCaseLabel);
                                     }
                                 } else if (!stringSwitch && !intSwitch) {
                                     log.error(label.pos(), Errors.ConstantLabelNotCompatible(pattype, seltype));

test/langtools/tools/javac/switchextra/EnumSwitchQualifiedErrors.java

@@ -23,7 +23,7 @@
 
 /**
  * @test
- * @bug 8300543 8309336
+ * @bug 8300543 8309336 8311825
  * @summary Check switches work correctly with qualified enum constants
  * @compile/fail/ref=EnumSwitchQualifiedErrors.out -XDrawDiagnostics EnumSwitchQualifiedErrors.java
 */
@@ -69,6 +69,30 @@ int testPatternMatchingSwitch5(Object e) {
         };
     }
 
+    int testQualifiedDuplicate1(Object o) {
+        return switch(o) {
+            case E1.A -> 1;
+            case E1.A -> 2;
+            default -> -1;
+        };
+    }
+
+    int testQualifiedDuplicate2(E1 e) {
+        return switch(e) {
+            case A -> 1;
+            case E1.A -> 2;
+            default -> -1;
+        };
+    }
+
+    int testQualifiedDuplicate3(E1 e) {
+        return switch(e) {
+            case E1.A -> 1;
+            case A -> 2;
+            default -> -1;
+        };
+    }
+
     sealed interface I {}
     enum E1 implements I { A; }
     enum E2 { A; }

test/langtools/tools/javac/switchextra/EnumSwitchQualifiedErrors.out

@@ -8,4 +8,7 @@ EnumSwitchQualifiedErrors.java:58:18: compiler.err.enum.label.must.be.enum.const
 EnumSwitchQualifiedErrors.java:65:18: compiler.err.pattern.or.enum.req
 EnumSwitchQualifiedErrors.java:66:18: compiler.err.pattern.or.enum.req
 EnumSwitchQualifiedErrors.java:67:18: compiler.err.pattern.expected
-10 errors
+EnumSwitchQualifiedErrors.java:75:18: compiler.err.duplicate.case.label
+EnumSwitchQualifiedErrors.java:83:18: compiler.err.duplicate.case.label
+EnumSwitchQualifiedErrors.java:91:18: compiler.err.duplicate.case.label
+13 errors