Description Manoj N Palat 2022-03-21 10:59:09 EDT

From bug 576746 comment 3 by Alexander Kriegisch

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public class SwitchPatternPreview2OK {
  static void constantLabelMustAppearBeforePattern(Integer o) {
    switch (o) {
      case -1, 1 -> System.out.println("special case:" + o);
      case Integer i && i > 0 -> System.out.println("positive integer: " + o);
      case Integer i -> System.out.println("other integer: " + o);
    }
  }
}

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I immediately got:

$ java -jar org.eclipse.jdt.core/target/org.eclipse.jdt.core-3.29.50-SNAPSHOT-batch-compiler.jar -18 --enable-preview ../AspectJ/tests/features199/java18/SwitchPatternPreview2OK.java
Picked up _JAVA_OPTIONS: -Djava.net.preferIPv4Stack=true
----------
1. ERROR in C:\Users\alexa\Documents\java-src\AspectJ\tests\features199\java18\SwitchPatternPreview2OK.java (at line 0)
        public class SwitchPatternPreview2OK {
        ^
Internal compiler error: java.lang.OutOfMemoryError: Java heap space at org.eclipse.jdt.internal.compiler.codegen.BranchLabel.addForwardReference(BranchLabel.java:57)
----------
2. WARNING in C:\Users\alexa\Documents\java-src\AspectJ\tests\features199\java18\SwitchPatternPreview2OK.java (at line 5)
        case Integer i && i > 0 -> System.out.println("positive integer: " + o);
             ^^^^^^^^^^^^^^^^^^
You are using a preview language feature that may or may not be supported in a future release
----------
3. WARNING in C:\Users\alexa\Documents\java-src\AspectJ\tests\features199\java18\SwitchPatternPreview2OK.java (at line 6)
        case Integer i -> System.out.println("other integer: " + o);
             ^^^^^^^^^
You are using a preview language feature that may or may not be supported in a future release
----------
Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
        at org.eclipse.jdt.internal.compiler.codegen.BranchLabel.addForwardReference(BranchLabel.java:57)
        at org.eclipse.jdt.internal.compiler.codegen.CaseLabel.branch(CaseLabel.java:35)
        at org.eclipse.jdt.internal.compiler.codegen.CodeStream.tableswitch(CodeStream.java:7552)
        at org.eclipse.jdt.internal.compiler.ast.SwitchStatement.generateCode(SwitchStatement.java:563)
        at org.eclipse.jdt.internal.compiler.ast.AbstractMethodDeclaration.generateCode(AbstractMethodDeclaration.java:354)
        at org.eclipse.jdt.internal.compiler.ast.AbstractMethodDeclaration.generateCode(AbstractMethodDeclaration.java:291)
        at org.eclipse.jdt.internal.compiler.ast.TypeDeclaration.generateCode(TypeDeclaration.java:761)
        at org.eclipse.jdt.internal.compiler.ast.TypeDeclaration.generateCode(TypeDeclaration.java:831)
        at org.eclipse.jdt.internal.compiler.ast.CompilationUnitDeclaration.generateCode(CompilationUnitDeclaration.java:412)
        at org.eclipse.jdt.internal.compiler.Compiler.process(Compiler.java:913)
        at org.eclipse.jdt.internal.compiler.ProcessTaskManager.run(ProcessTaskManager.java:145)
        at java.base/java.lang.Thread.run(Thread.java:833)

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Actually, originally I wanted to use some example code right from JEP 420, ...

public class SwitchPatternPreview2OK {
  static void constantLabelMustAppearBeforePattern(Object o) {
    switch (o) {
      case -1, 1 -> System.out.println("special case:" + o);
      case Integer i && i > 0 -> System.out.println("positive integer: " + o);
      case Integer i -> System.out.println("other integer: " + o);
      default -> System.out.println("non-integer: " + o);
    }
  }
}

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but that yielded:

$ java -jar org.eclipse.jdt.core/target/org.eclipse.jdt.core-3.29.50-SNAPSHOT-batch-compiler.jar -18 --enable-preview ../AspectJ/tests/features199/java18/SwitchPatternPreview2OK.java
Picked up _JAVA_OPTIONS: -Djava.net.preferIPv4Stack=true
----------
1. ERROR in C:\Users\alexa\Documents\java-src\AspectJ\tests\features199\java18\SwitchPatternPreview2OK.java (at line 4)
        case -1, 1 -> System.out.println("special case:" + o);
             ^^
Type mismatch: cannot convert from int to Object
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2. ERROR in C:\Users\alexa\Documents\java-src\AspectJ\tests\features199\java18\SwitchPatternPreview2OK.java (at line 4)
        case -1, 1 -> System.out.println("special case:" + o);
                 ^
Type mismatch: cannot convert from int to Object
----------
3. WARNING in C:\Users\alexa\Documents\java-src\AspectJ\tests\features199\java18\SwitchPatternPreview2OK.java (at line 5)
        case Integer i && i > 0 -> System.out.println("positive integer: " + o);
             ^^^^^^^^^^^^^^^^^^
You are using a preview language feature that may or may not be supported in a future release
----------
4. WARNING in C:\Users\alexa\Documents\java-src\AspectJ\tests\features199\java18\SwitchPatternPreview2OK.java (at line 6)
        case Integer i -> System.out.println("other integer: " + o);
             ^^^^^^^^^
You are using a preview language feature that may or may not be supported in a future release
----------
4 problems (2 errors, 2 warnings)

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But Javac also does not seem to like the int constants with an Object switch type. I have no idea why they chose that example for the spec.

I re-tested this with the upstream beta 18 branch, no AspectJ mixed in at all, pure JDT Core. So before you merge, better double-check. But maybe I was just misunderstanding the mailing list discussion,and this is actually still under development, as the open ticket suggests.
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