[msys+mingw] build error [-Werror=uninitialized]

[msys+mingw] build error [-Werror=uninitialized]

[asmwarrior]

I see the build error in the latest cvs:

mingw32-gcc -g -O2 -D__USE_MINGW_ACCESS   -I. -I../../gdb/gdb -I../../gdb/gdb/common -I../../gdb/gdb/config -DLOCALEDIR="\"/mingw/share/locale\"" -DHAVE_CONFIG_H -I../../gdb/gdb/../include/opcode -I../../gdb/gdb/../opcodes/.. -I../../gdb/gdb/../readline/.. -I../bfd -I../../gdb/gdb/../bfd -I../../gdb/gdb/../include -I../libdecnumber -I../../gdb/gdb/../libdecnumber  -I../../gdb/gdb/gnulib -Ignulib    -IE:/code/python272/include -IE:/code/python272/include -Wall -Wdeclaration-after-statement -Wpointer-arith -Wformat-nonliteral -Wno-pointer-sign -Wno-unused -Wunused-value -Wunused-function -Wno-switch -Wno-char-subscripts -Wmissing-prototypes -Wno-format -Werror -c -o gnu-v3-abi.o -MT gnu-v3-abi.o -MMD -MP -MF .deps/gnu-v3-abi.Tpo ../../gdb/gdb/gnu-v3-abi.c
../../gdb/gdb/gnu-v3-abi.c: In function 'print_one_vtable.isra.2':
../../gdb/gdb/gnu-v3-abi.c:892:33: error: 'addr' may be used uninitialized in this function [-Werror=uninitialized]
cc1.exe: all warnings being treated as errors
make[2]: *** [gnu-v3-abi.o] Error 1

So, I think it can be quickly fixed by using:
CORE_ADDR addr = 0;

Is this correct? I see the addr is used in the try catch block:

TRY_CATCH (ex, RETURN_MASK_ERROR)
	{
	  addr = value_as_address (vfn);
	}
       if (ex.reason < 0)
	printf_filtered (_("<error: %s>"), ex.message);
       else
	print_function_pointer_address (gdbarch, addr, gdb_stdout,
					opts->addressprint);

Not sure why it still report such error.


Yuanhui Zhang

Re: [msys+mingw] build error [-Werror=uninitialized]

[Yao Qi]

On 03/16/2012 09:56 AM, asmwarrior wrote:
> I see the build error in the latest cvs:
> 
> mingw32-gcc -g -O2 -D__USE_MINGW_ACCESS   -I. -I../../gdb/gdb
> -I../../gdb/gdb/common -I../../gdb/gdb/config
> -DLOCALEDIR="\"/mingw/share/locale\"" -DHAVE_CONFIG_H
> -I../../gdb/gdb/../include/opcode -I../../gdb/gdb/../opcodes/..
> -I../../gdb/gdb/../readline/.. -I../bfd -I../../gdb/gdb/../bfd
> -I../../gdb/gdb/../include -I../libdecnumber
> -I../../gdb/gdb/../libdecnumber  -I../../gdb/gdb/gnulib -Ignulib   
> -IE:/code/python272/include -IE:/code/python272/include -Wall
> -Wdeclaration-after-statement -Wpointer-arith -Wformat-nonliteral
> -Wno-pointer-sign -Wno-unused -Wunused-value -Wunused-function
> -Wno-switch -Wno-char-subscripts -Wmissing-prototypes -Wno-format
> -Werror -c -o gnu-v3-abi.o -MT gnu-v3-abi.o -MMD -MP -MF
> .deps/gnu-v3-abi.Tpo ../../gdb/gdb/gnu-v3-abi.c
> ../../gdb/gdb/gnu-v3-abi.c: In function 'print_one_vtable.isra.2':
> ../../gdb/gdb/gnu-v3-abi.c:892:33: error: 'addr' may be used
> uninitialized in this function [-Werror=uninitialized]
> cc1.exe: all warnings being treated as errors
> make[2]: *** [gnu-v3-abi.o] Error 1

I get the same error when building gdb on x86_64-linux.

> 
> So, I think it can be quickly fixed by using:
> CORE_ADDR addr = 0;
> 

Yes, this fixes the build error I got.

> Is this correct? I see the addr is used in the try catch block:
> 
> TRY_CATCH (ex, RETURN_MASK_ERROR)
>     {
>       addr = value_as_address (vfn);
>     }
>       if (ex.reason < 0)
>     printf_filtered (_("<error: %s>"), ex.message);
>       else
>     print_function_pointer_address (gdbarch, addr, gdb_stdout,
>                     opts->addressprint);
> 
> Not sure why it still report such error.

I didn't see any other errors.  What error did you see even after you
setting `addr' to 0?

-- 
Yao (齐尧)

Re: [msys+mingw] build error [-Werror=uninitialized]

[asmwarrior]

On 2012-3-16 15:24, Yao Qi wrote:
> I didn't see any other errors.  What error did you see even after you
> setting `addr' to 0?
See:

TRY_CATCH (ex, RETURN_MASK_ERROR)
     {
       addr = value_as_address (vfn);
     }
Which means addr is set before passed to print_function_pointer_address() call.
So I'm not sure why gcc report such warning.

Yuanhui Zhang

Re: [msys+mingw] build error [-Werror=uninitialized]

[Yao Qi]

On 03/16/2012 03:31 PM, asmwarrior wrote:
> TRY_CATCH (ex, RETURN_MASK_ERROR)
>     {
>       addr = value_as_address (vfn);
>     }
> Which means addr is set before passed to print_function_pointer_address() call.
> 
> So I'm not sure why gcc report such warning.

No idea on this.  Patch below fixes the problem on my box.

-- 
Yao (齐尧)

2012-03-16  Yao Qi  <yao@codesourcery.com>

index 0ba6ab5..5bfabe3 100644
--- a/gdb/gnu-v3-abi.c
+++ b/gdb/gnu-v3-abi.c
@@ -870,7 +870,7 @@ print_one_vtable (struct gdbarch *gdbarch, struct
value *value,
   for (i = 0; i <= max_voffset; ++i)
     {
       struct value *vfn;
-      CORE_ADDR addr;
+      CORE_ADDR addr = 0;
       volatile struct gdb_exception ex;

       printf_filtered ("[%d]: ", i);

[commit] [msys+mingw] build error [-Werror=uninitialized]

[Jan Kratochvil]

On Fri, 16 Mar 2012 08:44:37 +0100, Yao Qi wrote:
> On 03/16/2012 03:31 PM, asmwarrior wrote:
> > TRY_CATCH (ex, RETURN_MASK_ERROR)
> >     {
> >       addr = value_as_address (vfn);
> >     }
> > Which means addr is set before passed to print_function_pointer_address() call.
> > 
> > So I'm not sure why gcc report such warning.
> 
> No idea on this.  Patch below fixes the problem on my box.

Added there a comment like in other cases.

This improper warning happens with TRY_CATCH on older gccs.


Thanks,
Jan


http://sourceware.org/ml/gdb-cvs/2012-03/msg00203.html

--- src/gdb/ChangeLog	2012/03/15 18:53:42	1.14016
+++ src/gdb/ChangeLog	2012/03/16 08:18:07	1.14017
@@ -1,3 +1,9 @@
+2012-03-16  Yao Qi  <yao@codesourcery.com>
+	    Jan Kratochvil  <jan.kratochvil@redhat.com>
+
+	Fix false compilation warning.
+	* gnu-v3-abi.c (print_one_vtable): Initialize ADDR.
+
 2012-03-15  Jonathan Larmour  <jifl@eCosCentric.com>
 	    Pedro Alves  <pedro@codesourcery.com>
 
--- src/gdb/gnu-v3-abi.c	2012/03/15 15:43:11	1.70
+++ src/gdb/gnu-v3-abi.c	2012/03/16 08:18:09	1.71
@@ -869,8 +869,9 @@
 
   for (i = 0; i <= max_voffset; ++i)
     {
+      /* Initialize it just to avoid a GCC false warning.  */
+      CORE_ADDR addr = 0;
       struct value *vfn;
-      CORE_ADDR addr;
       volatile struct gdb_exception ex;
 
       printf_filtered ("[%d]: ", i);

Re: [commit] [msys+mingw] build error [-Werror=uninitialized]

[asmwarrior]

On 2012-3-16 16:19, Jan Kratochvil wrote:
> This improper warning happens with TRY_CATCH on older gccs.
In-fact, I'm using a modern GCC (GCC 4.6.3 under Windows).

Re: [commit] [msys+mingw] build error [-Werror=uninitialized]

[asmwarrior]

On 2012-3-16 16:23, asmwarrior wrote:
> On 2012-3-16 16:19, Jan Kratochvil wrote:
>> This improper warning happens with TRY_CATCH on older gccs.
> In-fact, I'm using a modern GCC (GCC 4.6.3 under Windows).
>

I filed a bug report in GCC, see:
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52602

Yuanhui Zhang