objc/6960: Compiler doesn't correct allocate object from -fconstant-string-class=

objc/6960: Compiler doesn't correct allocate object from -fconstant-string-class=

[daa]

>Number:         6960
>Category:       objc
>Synopsis:       Compiler doesn't correct allocate object from -fconstant-string-class=
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri Jun 07 09:46:01 PDT 2002
>Closed-Date:
>Last-Modified:
>Originator:     Aleksey Dukhnyakov
>Release:        unknown-1.0
>Organization:
>Environment:
Redhat Linux
>Description:
Compiler doesn't correct allocate object :

Please see minimized testcase bug1.m:

$ gcc -v
Reading specs from /home/daa/bin/../lib/gcc-lib/i686-pc-linux-gnu/3.1/specs
Configured with: ./configure  : (reconfigured) ./configure
Thread model: single
gcc version 3.1
$ gcc bug2.m -fconstant-string-class=NSConstantString -lobjc
bug2.m:1:2: warning: #import is obsolete, use an #ifndef wrapper in the header f
ile
$ a.out
isa=0x8055c40
_info=134556911
buffer=0x5
length=0
str=Hello len=5

As you can see compiler writes buffer to _info and length to buffer.
>How-To-Repeat:

>Fix:

>Release-Note:
>Audit-Trail:
>Unformatted:
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Re: objc/6960: Compiler doesn't correct allocate object from -fconstant-string-class=

[nicola]

Synopsis: Compiler doesn't correct allocate object from -fconstant-string-class=

Responsible-Changed-From-To: unassigned->nicola
Responsible-Changed-By: nicola
Responsible-Changed-When: Sun Sep  1 05:22:13 2002
Responsible-Changed-Why:
    Looking at it
State-Changed-From-To: open->closed
State-Changed-By: nicola
State-Changed-When: Sun Sep  1 05:22:13 2002
State-Changed-Why:
    The compiler is working properly.  In the testcase, the
    NSObject class contains an additional field _info in the
    ivar layout, which causes NSConstantString to have an
    additional ivar in the layout, which is not allowed.  
    I understand the point, but unfortunately this is not 
    supposed to work - the NSConstantString class ivar layout 
    is fixed.  I also agree it should be documented better,
    but that's it.

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=6960