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Prevent duplication of guard clause in switch expressions #8971

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Merged
mbien merged 1 commit into from
Nov 9, 2025
Merged

Prevent duplication of guard clause in switch expressions #8971

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2 changes: 1 addition & 1 deletion java/java.source.base/src/org/netbeans/modules/java/source/save/CasualDiff.java
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Original file line number Diff line number Diff line change
Expand Up @@ -2144,7 +2144,7 @@ protected int diffCase(JCCase oldT, JCCase newT, int[] bounds) {
if (oldT.guard != null && newT.guard != null) {
int[] guardBounds = getBounds(oldT.guard);
copyTo(localPointer, guardBounds[0]);
diffTree(oldT.guard, newT.guard, guardBounds);
localPointer = diffTree(oldT.guard, newT.guard, guardBounds);
} else if (oldT.guard != null && newT.guard == null) {
//TODO:
} else if (oldT.guard == null && newT.guard != null) {
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53 changes: 53 additions & 0 deletions java/java.source.base/test/unit/src/org/netbeans/api/java/source/gen/SwitchTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -657,6 +657,59 @@ public Void visitSwitch(SwitchTree node, Void p) {
assertEquals(golden, res);
}

// test as advised by lahodaj
public void testGuardPreserved() throws Exception {
testFile = new File(getWorkDir(), "Test.java");
String test
= """
public class Test {
void m(Object o) {
switch (o) {
case String str when str.isEmpty() -> System.err.println();
default -> {}
}
}
}
""";
String golden
= """
public class Test {
void m(Object o) {
switch (o) {
case String str when str.isEmpty() -> {
}
default -> {}
}
}
}
""";
TestUtilities.copyStringToFile(testFile, test.replace("|", ""));
JavaSource src = getJavaSource(testFile);
Task<WorkingCopy> task = new Task<WorkingCopy>() {
public void run(final WorkingCopy copy) throws IOException {
if (copy.toPhase(Phase.RESOLVED).compareTo(Phase.RESOLVED) < 0) {
return;
}
final TreeMaker make = copy.getTreeMaker();
new ErrorAwareTreePathScanner<Void, Void>() {
@Override
public Void visitCase(CaseTree node, Void p) {
if (!node.getLabels().isEmpty()) {
copy.rewrite(getCurrentPath().getLeaf(),
make.CasePatterns(node.getLabels(), node.getGuard(), make.Block(List.of(), false)));
}
return super.visitCase(node, p);
}
}.scan(copy.getCompilationUnit(), null);
}
};
src.runModificationTask(task).commit();
String res = TestUtilities.copyFileToString(testFile);
//System.err.println(res);
assertEquals(golden, res);
}


// XXX I don't understand what these are used for
@Override
String getSourcePckg() {
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