Re: [patch] ptype: show members of an unnamed struct inside an union

[Carlos Eduardo Seo <cseo@linux.vnet.ibm.com>]

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Joel

Here's a testcase. In order to see the issue, do the following:

1. Compile it with -g flag
2. Run gdb
3. b main
4. ptype struct my_page

You'll see:

type = struct my_page {
    union {
        struct {...};
    };
}

Using the proposed patch, you'll see:


type = struct my_page {
    union {
        struct {int mapping; };
    };
}

If you want, you may use a more complex union, such as:

struct my_page {
       union {
           struct {
               int mapping;
               long foo;
               char *pointer;
           };
           struct {
               char blah;
               int test;
           };
           struct {
               char blahblah;
           };
           struct {
           };
       };
};

Any questions, feel free to contact me.

Thanks and regards,

- --
Carlos Eduardo Seo
Software Engineer
IBM Linux Technology Center



Joel Brobecker wrote:
> Carlos,
>
>> The attached patched fixes an issue described on this post:
>>
>> http://sourceware.org/ml/gdb-patches/2002-04/msg01114.html
>
>> 2007-08-16   Carlos Eduardo Seo <cseo@linux.vnet.ibm.com>
>>
>>     gdb/c-typeprint.c (c_type_print_base): check value of
>>     TYPE_NFIELDS (type) when displaying members of an
>>     unnamed struct inside an union.
>
> Could you add a testcase for this issue? Being new at reviewing
> other people's patches, it's sometimes hard for me to understand
> what you are trying to do. A testcase would help in two ways: not
> only ensure that we do not regress in the future, but also help
> me understand clearly what it is that we're trying to fix.
>
> Thank you!
>
>> Index: src-git/gdb/c-typeprint.c
>> ===================================================================
>> --- src-git.orig/gdb/c-typeprint.c    2007-08-16 15:28:04.000000000 -0700
>> +++ src-git/gdb/c-typeprint.c    2007-08-16 15:29:07.000000000 -0700
>> @@ -735,7 +735,7 @@
>>          fputs_filtered (" ", stream);
>>      }
>>        wrap_here ("    ");
>> -      if (show < 0)
>> +      if ((show < 0) && (TYPE_NFIELDS (type) == 0))
>>      {
>>        /* If we just printed a tag name, no need to print anything
else.  */
>>        if (TYPE_TAG_NAME (type) == NULL)
>


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struct my_page {
       union {
           struct {
               int mapping;
           };
       };
};

main()
{
       struct my_page mypage;
}

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