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8314226: Series of colon-style fallthrough switch cases with guards c…
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…ompiled incorrectly

Reviewed-by: mcimadamore, vromero
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biboudis authored and Vicente Romero committed Sep 13, 2023
1 parent ff240a9 commit 3b0a6d2
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Showing 2 changed files with 218 additions and 1 deletion.
Original file line number Diff line number Diff line change
Expand Up @@ -524,6 +524,8 @@ private void handleSwitch(JCTree tree,
boolean previousCompletesNormally = false;
boolean hasDefault = false;

patchCompletingNormallyCases(cases);

for (var c : cases) {
List<JCCaseLabel> clearedPatterns = c.labels;
boolean hasJoinedNull =
Expand All @@ -541,7 +543,8 @@ private void handleSwitch(JCTree tree,
validCaseLabelList = clearedPatterns.head.hasTag(Tag.PATTERNCASELABEL);
}

if (validCaseLabelList && !previousCompletesNormally) {
if ((validCaseLabelList && !previousCompletesNormally) ||
c.guard != null) {
List<JCPatternCaseLabel> labels = clearedPatterns.stream().map(cp -> (JCPatternCaseLabel)cp).collect(List.collector());
bindingContext = new BasicBindingContext();
VarSymbol prevCurrentValue = currentValue;
Expand Down Expand Up @@ -657,6 +660,53 @@ private void handleSwitch(JCTree tree,
super.visitSwitchExpression((JCSwitchExpression) tree);
}
}

// Duplicates the block statement where needed.
// Processes cases in place, e.g.
// switch (obj) {
// case Integer _ when ((Integer) obj) > 0:
// case String _ when !((String) obj).isEmpty():
// return 1;
// ...
// }
// =>
// switch (typeSwitch(...)) {
// case 0:
// if (!((Integer)obj) > 0) { ... }
// return 1;
// case 1:
// if (!((String)obj).isEmpty()) { ... }
// return 1;
// ...
// }
private static void patchCompletingNormallyCases(List<JCCase> cases) {
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;
}
}

//where:
private void fixupContinue(JCTree switchTree, JCCase c, VarSymbol indexVariable, int currentCaseIndex) {
//inject 'index = currentCaseIndex + 1;` before continue which has the current switch as the target
Expand Down
167 changes: 167 additions & 0 deletions test/langtools/tools/javac/patterns/T8314226.java
Original file line number Diff line number Diff line change
@@ -0,0 +1,167 @@
/*
* Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
/**
* @test
* @bug 8314226
* @summary Series of colon-style fallthrough switch cases with guards compiled incorrectly
* @enablePreview
* @compile T8314226.java
* @run main T8314226
*/

public class T8314226 {
int multipleGuardedCases(Object obj) {
switch (obj) {
case Integer _ when ((Integer) obj) > 0:
case String _ when !((String) obj).isEmpty():
return 1;
default:
return -1;
}
}

int multipleGuardedCases2a(Object obj) {
switch (obj) {
case Integer _ when ((Integer) obj) > 0:
case Float _ when ((Float) obj) > 0.0f:
case String _ when !((String) obj).isEmpty():
return 1;
default:
return -1;
}
}

int multipleGuardedCases2b(Object obj) {
switch (obj) {
case Float _ when ((Float) obj) > 0.0f: // reversing the order
case Integer _ when ((Integer) obj) > 0:
case String _ when !((String) obj).isEmpty():
return 1;
default:
return -1;
}
}

int multipleGuardedCasesMultiplePatterns(Object obj) {
switch (obj) {
case String _ when !((String) obj).isEmpty():
case Integer _, Byte _ when ((Number) obj).intValue() > 0:
return 1;
default:
return -1;
}
}

int singleGuardedCase(Object obj) {
switch (obj) {
case String _ when !((String) obj).isEmpty():
return 1;
default:
return -1;
}
}

int multipleCasesWithReturn(Object obj) {
switch (obj) {
case Integer _ when ((Integer) obj) > 0:
case String _ when !((String) obj).isEmpty():
return 1;
case null:
return 2;
default:
return 3;
}
}

int multipleCasesWithEffectNoReturn(Object obj) {
int i = 0;
switch (obj) {
case Integer _ when ((Integer) obj) > 0:
case String _ when !((String) obj).isEmpty():
i = i + 1;
case null:
i = i + 10;
default:
i = i + 100;
}
return i;
}

int multipleCasesWithLoop(Object obj) {
int i = 0;
switch (obj) {
case Integer _ when ((Integer) obj) > 0:
case String _ when !((String) obj).isEmpty():
i = i + 1;
case null:
while (true) {
i = i + 10;
break;
}
default:
i = i + 100;
}

return i;
}

public static void main(String[] args) {
new T8314226().run();
}

private void run() {
assertEquals(1, multipleGuardedCases(42));
assertEquals(1, multipleGuardedCases("test"));
assertEquals(-1, multipleGuardedCases(""));
assertEquals(1, multipleGuardedCases2a(42.0f));
assertEquals(1, multipleGuardedCases2a("test"));
assertEquals(-1, multipleGuardedCases2a(""));
assertEquals(1, multipleGuardedCases2b(42.0f));
assertEquals(1, multipleGuardedCases2b("test"));
assertEquals(-1, multipleGuardedCases2b(""));
assertEquals(1, multipleGuardedCasesMultiplePatterns((byte) 42));
assertEquals(1, multipleGuardedCasesMultiplePatterns("test"));
assertEquals(-1, multipleGuardedCasesMultiplePatterns(""));
assertEquals(-1, singleGuardedCase(42));
assertEquals(1, singleGuardedCase("test"));
assertEquals(-1, singleGuardedCase(""));
assertEquals(1, multipleCasesWithReturn(42));
assertEquals(1, multipleCasesWithReturn("test"));
assertEquals(2, multipleCasesWithReturn(null));
assertEquals(3, multipleCasesWithReturn(""));
assertEquals(111, multipleCasesWithEffectNoReturn(42));
assertEquals(111, multipleCasesWithEffectNoReturn("test"));
assertEquals(110, multipleCasesWithEffectNoReturn(null));
assertEquals(100, multipleCasesWithEffectNoReturn(""));
assertEquals(111, multipleCasesWithLoop(42));
assertEquals(111, multipleCasesWithLoop("test"));
assertEquals(110, multipleCasesWithLoop(null));
assertEquals(100, multipleCasesWithLoop(""));
}

void assertEquals(Object expected, Object actual) {
if (expected != actual) {
throw new AssertionError("Expected: " + expected + ", but got: " + actual);
}
}
}

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