diff mbox series

gdb: Fix -Wuninitialied issue

Message ID OS3P286MB21527F155CDDA3DCFCAA6F29F0F1A@OS3P286MB2152.JPNP286.PROD.OUTLOOK.COM
State New
Headers
Series gdb: Fix -Wuninitialied issue |

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Commit Message

Enze Li Sept. 12, 2023, 8:22 a.m. UTC 
  I see the following warning when building GDB on FreeBSD/amd64 with
Clang 14,

======================================================================
  CXX    mdebugread.o
mdebugread.c:1069:3: error: variable 'f' is uninitialized when used here [-Werror,-Wuninitialized]
                f->set_loc_enumval (tsym.value);
                ^
mdebugread.c:836:17: note: initialize the variable 'f' to silence this warning
        struct field *f;
                       ^
                        = nullptr
======================================================================

after digging a little, I realized that we can not simply do what
Clang 14 says.

The root cause of this issue is that we lost the initialization of
the variable 'f' in this commit,

  commit 2774f2dad5f05e68771c07df6ab0fb23baa2118e
  Date:   Thu Aug 31 09:37:44 2023 +0200

      [gdb/symtab] Factor out type::{alloc_fields,copy_fields}

we have made these modifications,

----------------------------------------------------------------------

base-commit: 318d3bda5cad124bd11eebb0349d0f183ba625b1

Comments

Tom de Vries Sept. 12, 2023, 9:09 a.m. UTC | #1 
On 9/12/23 10:22, Enze Li wrote:
> I see the following warning when building GDB on FreeBSD/amd64 with
> Clang 14,
> 
> ======================================================================
>    CXX    mdebugread.o
> mdebugread.c:1069:3: error: variable 'f' is uninitialized when used here [-Werror,-Wuninitialized]
>                  f->set_loc_enumval (tsym.value);
>                  ^
> mdebugread.c:836:17: note: initialize the variable 'f' to silence this warning
>          struct field *f;
>                         ^
>                          = nullptr
> ======================================================================
> 
> after digging a little, I realized that we can not simply do what
> Clang 14 says.
> 
> The root cause of this issue is that we lost the initialization of
> the variable 'f' in this commit,
> 
>    commit 2774f2dad5f05e68771c07df6ab0fb23baa2118e
>    Date:   Thu Aug 31 09:37:44 2023 +0200
> 
>        [gdb/symtab] Factor out type::{alloc_fields,copy_fields}
> 

Hi,

thanks for fixing this.  I've reviewed my commit once more, and only 
found the instance that this patch fixes.

LGTM.

Approved-By: Tom de Vries <tdevries@suse.de>

Thanks,
- Tom

> we have made these modifications,
> 
> ----------------------------------------------------------------------
> --- a/gdb/mdebugread.c
> +++ b/gdb/mdebugread.c
> @@ -1034,9 +1034,7 @@ parse_symbol (SYMR *sh, union aux_ext *ax, char *ext_sh, int bigend,
> 
>          t->set_code (type_code);
>          t->set_length (sh->value);
> -       t->set_num_fields (nfields);
> -       f = ((struct field *) TYPE_ALLOC (t, nfields * sizeof (struct field)));
> -       t->set_fields (f);
> +       t->alloc_fields (nfields, false);
> ----------------------------------------------------------------------
> 
> The problem is that the variable 'f' is used in the second half of
> parse_symbol, that's why Clang complained.
> 
> To fix this issue we need to ensure that the varibale 'f' is
> initialized.  Calling the fields method is an obvious way to fix this
> issue.
> 
> Tested on FreeBSD/amd64 by rebuilding.
> ---
>   gdb/mdebugread.c | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/gdb/mdebugread.c b/gdb/mdebugread.c
> index ea3e15be53b2..9cb30ce0acd0 100644
> --- a/gdb/mdebugread.c
> +++ b/gdb/mdebugread.c
> @@ -1035,6 +1035,7 @@ parse_symbol (SYMR *sh, union aux_ext *ax, char *ext_sh, int bigend,
>   	t->set_code (type_code);
>   	t->set_length (sh->value);
>   	t->alloc_fields (nfields);
> +	f = t->fields();
>   
>   	if (type_code == TYPE_CODE_ENUM)
>   	  {
> 
> base-commit: 318d3bda5cad124bd11eebb0349d0f183ba625b1
Tom de Vries Sept. 12, 2023, 9:11 a.m. UTC | #2 
On 9/12/23 11:09, Tom de Vries via Gdb-patches wrote:
> On 9/12/23 10:22, Enze Li wrote:
>> I see the following warning when building GDB on FreeBSD/amd64 with
>> Clang 14,
>>
>> ======================================================================
>>    CXX    mdebugread.o
>> mdebugread.c:1069:3: error: variable 'f' is uninitialized when used 
>> here [-Werror,-Wuninitialized]
>>                  f->set_loc_enumval (tsym.value);
>>                  ^
>> mdebugread.c:836:17: note: initialize the variable 'f' to silence this 
>> warning
>>          struct field *f;
>>                         ^
>>                          = nullptr
>> ======================================================================
>>
>> after digging a little, I realized that we can not simply do what
>> Clang 14 says.
>>
>> The root cause of this issue is that we lost the initialization of
>> the variable 'f' in this commit,
>>
>>    commit 2774f2dad5f05e68771c07df6ab0fb23baa2118e
>>    Date:   Thu Aug 31 09:37:44 2023 +0200
>>
>>        [gdb/symtab] Factor out type::{alloc_fields,copy_fields}
>>
> 
> Hi,
> 
> thanks for fixing this.  I've reviewed my commit once more, and only 
> found the instance that this patch fixes.
> 
> LGTM.
> 
> Approved-By: Tom de Vries <tdevries@suse.de>
> 

Forgot to mention: before pushing, please fix the typo in $subject:

Wuninitialied -> Wuninitialized.

Thanks,
- Tom

>> we have made these modifications,
>>
>> ----------------------------------------------------------------------
>> --- a/gdb/mdebugread.c
>> +++ b/gdb/mdebugread.c
>> @@ -1034,9 +1034,7 @@ parse_symbol (SYMR *sh, union aux_ext *ax, char 
>> *ext_sh, int bigend,
>>
>>          t->set_code (type_code);
>>          t->set_length (sh->value);
>> -       t->set_num_fields (nfields);
>> -       f = ((struct field *) TYPE_ALLOC (t, nfields * sizeof (struct 
>> field)));
>> -       t->set_fields (f);
>> +       t->alloc_fields (nfields, false);
>> ----------------------------------------------------------------------
>>
>> The problem is that the variable 'f' is used in the second half of
>> parse_symbol, that's why Clang complained.
>>
>> To fix this issue we need to ensure that the varibale 'f' is
>> initialized.  Calling the fields method is an obvious way to fix this
>> issue.
>>
>> Tested on FreeBSD/amd64 by rebuilding.
>> ---
>>   gdb/mdebugread.c | 1 +
>>   1 file changed, 1 insertion(+)
>>
>> diff --git a/gdb/mdebugread.c b/gdb/mdebugread.c
>> index ea3e15be53b2..9cb30ce0acd0 100644
>> --- a/gdb/mdebugread.c
>> +++ b/gdb/mdebugread.c
>> @@ -1035,6 +1035,7 @@ parse_symbol (SYMR *sh, union aux_ext *ax, char 
>> *ext_sh, int bigend,
>>       t->set_code (type_code);
>>       t->set_length (sh->value);
>>       t->alloc_fields (nfields);
>> +    f = t->fields();
>>       if (type_code == TYPE_CODE_ENUM)
>>         {
>>
>> base-commit: 318d3bda5cad124bd11eebb0349d0f183ba625b1
>
Enze Li Sept. 12, 2023, 1:42 p.m. UTC | #3 
On Tue, Sep 12 2023 at 11:11:05 AM +0200, Tom de Vries wrote:

> On 9/12/23 11:09, Tom de Vries via Gdb-patches wrote:
>> On 9/12/23 10:22, Enze Li wrote:
>>> I see the following warning when building GDB on FreeBSD/amd64 with
>>> Clang 14,
>>>
>>> ======================================================================
>>>    CXX    mdebugread.o
>>> mdebugread.c:1069:3: error: variable 'f' is uninitialized when used
>>> here [-Werror,-Wuninitialized]
>>>                  f->set_loc_enumval (tsym.value);
>>>                  ^
>>> mdebugread.c:836:17: note: initialize the variable 'f' to silence
>>> this warning
>>>          struct field *f;
>>>                         ^
>>>                          = nullptr
>>> ======================================================================
>>>
>>> after digging a little, I realized that we can not simply do what
>>> Clang 14 says.
>>>
>>> The root cause of this issue is that we lost the initialization of
>>> the variable 'f' in this commit,
>>>
>>>    commit 2774f2dad5f05e68771c07df6ab0fb23baa2118e
>>>    Date:   Thu Aug 31 09:37:44 2023 +0200
>>>
>>>        [gdb/symtab] Factor out type::{alloc_fields,copy_fields}
>>>
>> Hi,
>> thanks for fixing this.  I've reviewed my commit once more, and only
>> found the instance that this patch fixes.
>> LGTM.
>> Approved-By: Tom de Vries <tdevries@suse.de>
>> 
>
> Forgot to mention: before pushing, please fix the typo in $subject:
>
> Wuninitialied -> Wuninitialized.
>

Okey, fixed.  I'm checking this in now.

Best Regards,
Enze

> Thanks,
> - Tom
>
>>> we have made these modifications,
>>>
>>> ----------------------------------------------------------------------
>>> --- a/gdb/mdebugread.c
>>> +++ b/gdb/mdebugread.c
>>> @@ -1034,9 +1034,7 @@ parse_symbol (SYMR *sh, union aux_ext *ax,
>>> char *ext_sh, int bigend,
>>>
>>>          t->set_code (type_code);
>>>          t->set_length (sh->value);
>>> -       t->set_num_fields (nfields);
>>> -       f = ((struct field *) TYPE_ALLOC (t, nfields * sizeof
>>> (struct field)));
>>> -       t->set_fields (f);
>>> +       t->alloc_fields (nfields, false);
>>> ----------------------------------------------------------------------
>>>
>>> The problem is that the variable 'f' is used in the second half of
>>> parse_symbol, that's why Clang complained.
>>>
>>> To fix this issue we need to ensure that the varibale 'f' is
>>> initialized.  Calling the fields method is an obvious way to fix this
>>> issue.
>>>
>>> Tested on FreeBSD/amd64 by rebuilding.
>>> ---
>>>   gdb/mdebugread.c | 1 +
>>>   1 file changed, 1 insertion(+)
>>>
>>> diff --git a/gdb/mdebugread.c b/gdb/mdebugread.c
>>> index ea3e15be53b2..9cb30ce0acd0 100644
>>> --- a/gdb/mdebugread.c
>>> +++ b/gdb/mdebugread.c
>>> @@ -1035,6 +1035,7 @@ parse_symbol (SYMR *sh, union aux_ext *ax,
>>> char *ext_sh, int bigend,
>>>       t->set_code (type_code);
>>>       t->set_length (sh->value);
>>>       t->alloc_fields (nfields);
>>> +    f = t->fields();
>>>       if (type_code == TYPE_CODE_ENUM)
>>>         {
>>>
>>> base-commit: 318d3bda5cad124bd11eebb0349d0f183ba625b1
>>
diff mbox series

Patch

--- a/gdb/mdebugread.c
+++ b/gdb/mdebugread.c
@@ -1034,9 +1034,7 @@  parse_symbol (SYMR *sh, union aux_ext *ax, char *ext_sh, int bigend,

        t->set_code (type_code);
        t->set_length (sh->value);
-       t->set_num_fields (nfields);
-       f = ((struct field *) TYPE_ALLOC (t, nfields * sizeof (struct field)));
-       t->set_fields (f);
+       t->alloc_fields (nfields, false);
----------------------------------------------------------------------

The problem is that the variable 'f' is used in the second half of
parse_symbol, that's why Clang complained.

To fix this issue we need to ensure that the varibale 'f' is
initialized.  Calling the fields method is an obvious way to fix this
issue.

Tested on FreeBSD/amd64 by rebuilding.
---
 gdb/mdebugread.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/gdb/mdebugread.c b/gdb/mdebugread.c
index ea3e15be53b2..9cb30ce0acd0 100644
--- a/gdb/mdebugread.c
+++ b/gdb/mdebugread.c
@@ -1035,6 +1035,7 @@  parse_symbol (SYMR *sh, union aux_ext *ax, char *ext_sh, int bigend,
 	t->set_code (type_code);
 	t->set_length (sh->value);
 	t->alloc_fields (nfields);
+	f = t->fields();
 
 	if (type_code == TYPE_CODE_ENUM)
 	  {