[Bug middle-end/24129] New: [4.0 4.1 regression] bogus warning <var> is used uninitialized in this function

[Bug middle-end/24129] New: [4.0 4.1 regression] bogus warning <var> is used uninitialized in this function

[doko at debian dot org]

$ gcc -O3 -c -Wall -fno-strict-aliasing marshal.i
../Python/marshal.c: In function 'PyMarshal_ReadShortFromFile':
../Python/marshal.c:342: warning: 'rf.end' is used uninitialized in this function
../Python/marshal.c:342: warning: 'rf.ptr' is used uninitialized in this function

The warning is not shown with 3.4 CVS, seen with 4.0.2 and CVS HEAD 20050922,
using -fno-inline-functions avoids the warning.

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           Summary: [4.0 4.1 regression] bogus warning <var> is used
                    uninitialized in this function
           Product: gcc
           Version: 4.0.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: middle-end
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: doko at debian dot org
                CC: gcc-bugs at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24129

[Bug middle-end/24129] [4.0 4.1 regression] bogus warning <var> is used uninitialized in this function

[doko at debian dot org]

------- Additional Comments From doko at debian dot org  2005-09-29 20:24 -------
Created an attachment (id=9841)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=9841&action=view)
preprocessed source


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24129

[Bug middle-end/24129] [4.0 4.1 regression] bogus warning <var> is used uninitialized in this function

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-09-29 20:26 -------
I really doubt this is bogus but I have not looked into the source yet.

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24129

[Bug middle-end/24129] [4.0 4.1 regression] bogus warning <var> is used uninitialized in this function

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-09-29 20:35 -------
Lets look at the two functions:

static int
r_short(RFILE *p)
{ 
 register short x;
 x = ((p)->fp ? _IO_getc ((p)->fp) : (((p)->ptr != (p)->end) ? (unsigned char)*(p)->ptr++ : (-1)));
 x |= ((p)->fp ? _IO_getc ((p)->fp) : (((p)->ptr != (p)->end) ? (unsigned char)*(p)->ptr++ : (-1))) << 8;

 x |= -(x & 0x8000);
 return x;
}

int
PyMarshal_ReadShortFromFile(FILE *fp)
{
 WFILE rf;
 rf.fp = fp;
 rf.strings = ((void *)0);
 return r_short(&rf);
}

It is obvious that the warnings are valid as rf.end and rf.ptr is not initialized in 
PyMarshal_ReadShortFromFile.  There are no way to know that the arguments passing to 
PyMarshal_ReadShortFromFile are non null from the source you gave so the warning is correct.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |INVALID


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24129

[Bug middle-end/24129] [4.0 4.1 regression] bogus warning <var> is used uninitialized in this function

[doko at debian dot org]

------- Additional Comments From doko at debian dot org  2005-09-29 20:40 -------
The line number points to the inlined function, not to
'PyMarshal_ReadShortFromFile'. Is this intended?


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24129

[Bug middle-end/24129] [4.0 4.1 regression] bogus warning <var> is used uninitialized in this function

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-09-29 20:44 -------
(In reply to comment #4)
> The line number points to the inlined function, not to
> 'PyMarshal_ReadShortFromFile'. Is this intended?
In a way yes but that would be PR 17506 which I have not submitted the patch yet.

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24129