Bug in com.sun.tools.javac.tree.Pretty

[Jonathan Gibbons]

Normally, when someone makes a comment like "it should show up soon", it 
should show up within about 24 hours or less, depending on the 
propogation delay between the systems involved.

I agree that this issue has not shown up on bugs.sun.com, but I don't 
see any reason why it should not be visible externally. I'll have to 
follow up with internal folk to find out what is going on.

-- Jon

On 09/09/2013 11:54 AM, Matthew Dempsky wrote:
> Thanks Jonathan!
>
> http://bugs.sun.com/view_bug.do?bug_id=8024415 still tells me "This 
> bug is not available", and clicking on the FAQ page 
> (http://bugs.sun.com/faq.do) just gives me a blank page (except for 
> header links).  Can you clarify how much longer I should expect before 
> the bug report is available?
>
>
> On Fri, Sep 6, 2013 at 9:08 AM, Jonathan Gibbons 
> <jonathan.gibbons at oracle.com <mailto:jonathan.gibbons at oracle.com>> wrote:
>
>     Matthew,
>
>     Thank you. This is being tracked as 8024415.  It should show up
>     soon on bugs.sun.com <http://bugs.sun.com>.
>
>     -- Jon
>
>
>     On 09/05/2013 11:10 PM, Matthew Dempsky wrote:
>>     Hi Java compiler developers,
>>
>>     I noticed a bug in javac's JCTree pretty printer: it mishandles
>>     the precedence rules when pretty printing JCConditional trees.
>>      The "condition" subexpression should be pretty printed at
>>     precedence condPrec+1 instead of condPrec.
>>
>>     I've put together a short test program demonstrating this bug,
>>     included below.  It constructs and pretty prints two different
>>     nested conditional trees, but they generate identical output.
>>
>>     Additionally, but less severely, the "true" subexpression can be
>>     printed at noPrec without introducing any ambiguity; e.g., "x ? y
>>     = 1 : z" will parse the same as "x ? (y = 1) : z" anyway, so it's
>>     unnecessary (but also not incorrect) for Pretty to print the latter.
>>
>>     I believe (but have not verified) that these can both be fixed by
>>     changing Pretty.visitConditional() to:
>>
>>               printExpr(tree.cond, TreeInfo.condPrec + 1);
>>                 print(" ? ");
>>               printExpr(tree.truepart);
>>               print(" : ");
>>               printExpr(tree.falsepart, TreeInfo.condPrec);
>>
>>     I discovered this bug in what I believe to be jdk7u40, but it
>>     looks like it's still present in jdk8 langtools at tip:
>>     http://hg.openjdk.java.net/jdk8/jdk8/langtools/file/tip/src/share/classes/com/sun/tools/javac/tree/Pretty.java
>>
>>     Thanks
>>
>>
>>     Test program:
>>
>>     package prettybug;
>>
>>     import com.sun.tools.javac.file.JavacFileManager;
>>     import com.sun.tools.javac.tree.Pretty;
>>     import com.sun.tools.javac.tree.TreeMaker;
>>     import com.sun.tools.javac.util.Context;
>>
>>     import java.io.PrintWriter;
>>
>>     public class Bug {
>>       public static void main(String[] args) throws Exception {
>>     Context ctx = new Context();
>>     JavacFileManager.preRegister(ctx);
>>     TreeMaker maker = TreeMaker.instance(ctx);
>>
>>     PrintWriter writer = new PrintWriter(System.out);
>>     Pretty pretty = new Pretty(writer, true);
>>
>>     writer.println("These two trees should print differently:");
>>
>>     pretty.printExpr(
>>     maker.Conditional(
>>     maker.Conditional(
>>         maker.Literal(1),
>>       maker.Literal(2),
>>       maker.Literal(3)),
>>     maker.Literal(4),
>>     maker.Literal(5)));
>>     writer.println();
>>
>>     pretty.printExpr(
>>     maker.Conditional(
>>     maker.Literal(1),
>>     maker.Literal(2),
>>     maker.Conditional(
>>       maker.Literal(3),
>>       maker.Literal(4),
>>       maker.Literal(5))));
>>     writer.println();
>>
>>     writer.println();
>>
>>     writer.println("This expression is unambiguous even without the
>>     parentheses:");
>>
>>     pretty.printExpr(
>>     maker.Conditional(
>>     maker.Literal(1),
>>     maker.Assign(
>>       maker.Literal(2),
>>       maker.Literal(3)),
>>     maker.Literal(4)));
>>     writer.println();
>>
>>     writer.flush();
>>       }
>>     }
>
>

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