[Bug c/20189] New: assignment error in inline function

[Bug c/20189] New: assignment error in inline function

[dirk at cle-mens dot de]

This error was similar to bug #20185,
but now it is a C-Programm and not C++


// Postet by dirk@cle-mens.de
// Compiler Error found:
//	gcc (GCC) 3.3.4 (pre 3.3.5 20040809)
//	under SuSE Linux kernel 2.6.8-24.10-default (i386)
//
// This Bug is a little bit different in relation to bug #20184
//
// If this littel programm is compiled with the option -O2
// the assignment in the inline function was wrong.
// If I remove the 'inline' of any of both functions the result is correct.
//
// Compiled with: gcc -Wall error.cpp
//		-> OK, last line of printout: 0000000000000001
//
// Compiled with: gcc -Wall -O2 error.cpp
//		-> ERROR, last line of printout: 080482c500000001
//
// Compiled with: gcc -Wall -O2 error.cpp
//  but without 'inline' for GenData() and/or GetData()
//		-> OK, last line of printout: 0000000000000001
//

#include <stdlib.h>
#include <stdio.h>

typedef unsigned int uint32;
typedef unsigned long long uint64;

struct data
{
    uint32 lo;
    uint32 hi;
};

inline struct data * GenData ( struct data * d, uint32 num )
{
    d->lo = num; d->hi = -(num<0);
    return d;
}

inline uint64 GetData ( const struct data * d )
{
    return *(uint64*)&d->lo;
}

int main ( int argc, char ** argv )
{ 
    printf("sizeof(uint32)=%d\n",sizeof(uint32));
    printf("sizeof(uint64)=%d\n",sizeof(uint64));
    printf("sizeof(data)=  %d\n",sizeof(struct data));

    uint32 tab[] = { 1,1,1,1,1 };
    uint32 *p = tab;

    struct data D;
    printf("D=%p lo=%p hi=%p\n",&D,&D.lo,&D.hi);

    uint64 u64 = GetData(GenData(&D,*p++));
    printf("%016llx\n",u64);

    return 0;
}

-- 
           Summary: assignment error in inline function
           Product: gcc
           Version: 3.3.4
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: dirk at cle-mens dot de
                CC: gcc-bugs at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20189

[Bug c/20189] assignment error in inline function

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-02-24 14:04 -------
Invalid you are violating C90/C99 aliasing rules.

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20189

[Bug c/20189] assignment error in inline function

[dirk at cle-mens dot de]

------- Additional Comments From dirk at cle-mens dot de  2005-02-26 10:35 -------
(In reply to comment #1)
> Invalid you are violating C90/C99 aliasing rules.

Ok. But where is the compiler warning?

The dokumentation of gcc says: (man gcc)
-Wstrict-aliasing
 This option is only active when -fstrict-aliasing is active.  It
 warns about code which might break the strict aliasing rules that
 the compiler is using for optimization. The warning does not
 catch all cases, but does attempt to catch the more common pit‐
 falls. It is included in -Wall.

But the compiler don't give any warning!
And this is a compiler error in category warnings.

P.S.: I have minimized the Programm that shows this error:

#include <stdlib.h>
#include <stdio.h>

typedef unsigned int uint32;
typedef unsigned long long uint64;

struct data
{
    uint32 lo;
    uint32 hi;
};

inline uint64 GetData ( const struct data * d )
{
    const uint64 *p = (uint64*)d; // <<<<<<<<<<<<<<<<<<<<
    return *p;
}

int main( int argc, char ** argv )
{
    struct data D = {1,2};
    uint64 u64 = GetData(&D);
    printf("%016llx\n",u64);
    return 0;
}

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20189

[Bug c/20189] assignment error in inline function

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-02-26 14:26 -------
Because that would be PR 13049.

*** This bug has been marked as a duplicate of 13049 ***

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20189