Improving the desugared code.

lahodaj · Sep 8, 2023 · 283b0b0 · 283b0b0
1 parent 52bf0e3
commit 283b0b0
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Showing 2 changed files with 36 additions and 15 deletions.
diff --git a/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/TransPatterns.java b/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/TransPatterns.java
@@ -680,15 +680,30 @@ private void handleSwitch(JCTree tree,
     //     ...
     // }
     private static void patchCompletingNormallyCases(List<JCCase> cases) {
-        for (int j = cases.size() - 1; j >= 0; j--) {
-            var currentCase = cases.get(j);
-
-            if (currentCase != cases.last() && (currentCase.guard != null || TreeInfo.isNullCaseLabel(currentCase.labels.head)) &&
-                    currentCase.caseKind == CaseKind.STATEMENT &&
-                    currentCase.completesNormally) {
-                var nextCase = cases.get(j + 1);
-                currentCase.stats = currentCase.stats.appendList(nextCase.stats);
+        while (cases.nonEmpty()) {
+            var currentCase = cases.head;
+
+            if (currentCase.caseKind == CaseKind.STATEMENT &&
+                currentCase.completesNormally &&
+                cases.tail.nonEmpty() &&
+                cases.tail.head.guard != null) {
+                ListBuffer<JCStatement> newStatements = new ListBuffer<>();
+                List<JCCase> copyFrom = cases;
+
+                while (copyFrom.nonEmpty()) {
+                    newStatements.appendList(copyFrom.head.stats);
+
+                    if (!copyFrom.head.completesNormally) {
+                        break;
+                    }
+
+                    copyFrom = copyFrom.tail;
+                };
+
+                currentCase.stats = newStatements.toList();
             }
+
+            cases = cases.tail;
         }
     }
 

diff --git a/test/langtools/tools/javac/patterns/T8314226.java b/test/langtools/tools/javac/patterns/T8314226.java
@@ -108,15 +108,21 @@ case Integer _ when ((Integer) obj) > 0:
     }
 
     int multipleCasesWithLoop(Object obj) {
+        int i = 0;
         switch (obj) {
             case Integer _ when ((Integer) obj) > 0:
             case String _ when !((String) obj).isEmpty():
-                return 1;
+                i = i + 1;
             case null:
-                while (true) {break;}
+                while (true) {
+                    i = i + 10;
+                    break;
+                }
             default:
-                return 3;
+                i = i + 100;
         }
+
+        return i;
     }
 
     public static void main(String[] args) {
@@ -147,10 +153,10 @@ private void run() {
         assertEquals(111, multipleCasesWithEffectNoReturn("test"));
         assertEquals(110, multipleCasesWithEffectNoReturn(null));
         assertEquals(100, multipleCasesWithEffectNoReturn(""));
-        assertEquals(1, multipleCasesWithLoop(42));
-        assertEquals(1, multipleCasesWithLoop("test"));
-        assertEquals(3, multipleCasesWithLoop(null));
-        assertEquals(3, multipleCasesWithLoop(""));
+        assertEquals(111, multipleCasesWithLoop(42));
+        assertEquals(111, multipleCasesWithLoop("test"));
+        assertEquals(110, multipleCasesWithLoop(null));
+        assertEquals(100, multipleCasesWithLoop(""));
     }
 
     void assertEquals(Object expected, Object actual) {