www.digitalmars.com         C & C++   DMDScript  

D.gnu - [Issue 1766] New: segfault writing to a string variable...

reply d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=1766

           Summary: segfault writing to a string variable...
           Product: DGCC aka GDC
           Version: 0.24
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P2
         Component: glue layer
        AssignedTo: dvdfrdmn users.sf.net
        ReportedBy: funisher gmail.com


gentoo gdc 0.24, x86_64, no cflags

here is a simple test case:

void main() {
        string lala = "     ";
        lala[0] = '1';
}

however, reading is fine...

void main() {
        string lala;
        lala = "-----";
        printf("%c %d", lala[0], lala.length); // prints '- 5'
}


--
Jan 02 2008
next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=1766






I don't think this is a bug. Its working as I would expect it to.

The identifier 'lala' is not a VARIABLE, its a reference to a string literal
and literals are in read-only memory on Linux, thus you can't write to it. The
segfault is the operating system's reaction to the attempt.

Use this instead ...

void main() {
        string lala = "     ".dup; // Take a writable copy of the literal.
        lala[0] = '1';
}


--
Jan 02 2008
prev sibling parent reply d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=1766


bugzilla digitalmars.com changed:

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





This is not a bug, string literals are read-only.


--
Jan 02 2008
parent reply Kenny B <funisher gmail.com> writes:
d-bugmail puremagic.com wrote:

 http://d.puremagic.com/issues/show_bug.cgi?id=1766
 
 
 bugzilla digitalmars.com changed:
 
            What    |Removed                     |Added
 ----------------------------------------------------------------------------
              Status|NEW                         |RESOLVED
          Resolution|                            |INVALID
 
 
 
 

 This is not a bug, string literals are read-only.
 
 


Ok, I understand it's not a bug and it makes perfect sense, but why did
the same exact code work as I originally expected with dmd-2.003?
shouldn't that also be read-only?

Is it a bug that dmd works?
Jan 03 2008
parent Derek Parnell <derek nomail.afraid.org> writes:
On Fri, 04 Jan 2008 00:03:13 +0100, Kenny B wrote:


 d-bugmail puremagic.com wrote:

 http://d.puremagic.com/issues/show_bug.cgi?id=1766
 
 bugzilla digitalmars.com changed:
 
            What    |Removed                     |Added
 ----------------------------------------------------------------------------
              Status|NEW                         |RESOLVED
          Resolution|                            |INVALID
 

 This is not a bug, string literals are read-only.
 


 
 Ok, I understand it's not a bug and it makes perfect sense, but why did
 the same exact code work as I originally expected with dmd-2.003?
 shouldn't that also be read-only?
 
 Is it a bug that dmd works?


Yes. The Linux compiler places literals in read-only memory but the Windows
one doesn't. This is sort of fixed in D v2.

-- 
Derek
(skype: derek.j.parnell)
Melbourne, Australia
4/01/2008 2:25:46 PM
Jan 03 2008