http://d.puremagic.com/issues/show_bug.cgi?id=2990

           Summary: TypeInfo.init() returns invalid array
           Product: D
           Version: 1.044
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: bugzilla@digitalmars.com
        ReportedBy: nfxjfg@gmail.com


Sometimes, the array TypeInfo.init() returns has a length, but ptr is null. Accessing an element of such an array causes segfaults. This can't be right. TypeInfo.init() should just return an empty array.

Example follows. This outputs "ptr=0000 length=4".

import std.stdio;

struct X {
   int y;
}

void main() {
   TypeInfo ti = typeid(X);
   writefln("ptr=%s length=%s", ti.init.ptr, ti.init.length);
}

-- 
Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email
------- You are receiving this mail because: -------

http://d.puremagic.com/issues/show_bug.cgi?id=2990


nfxjfg@gmail.com changed:

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


-- 
Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email
------- You are receiving this mail because: -------

http://d.puremagic.com/issues/show_bug.cgi?id=2990


Brad Roberts <braddr@puremagic.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |REOPENED
                 CC|                            |braddr@puremagic.com
         Resolution|WONTFIX                     |


-- 
Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email
------- You are receiving this mail because: -------

http://d.puremagic.com/issues/show_bug.cgi?id=2990


Steven Schveighoffer <schveiguy@yahoo.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |schveiguy@yahoo.com


--- Comment #1 from Steven Schveighoffer <schveiguy@yahoo.com> 2011-01-07 06:46:51 PST ---
This is really a documentation issue.  The init() is correct, as I discovered when fixing a recent bug.

Essentially, when the ptr is null, but the length is non-zero, the meaning is that the init value for that type is init().length bytes of zero.  This cuts down on having to store an array of zeros in the binary.

The documentation for init() says:

"Return default initializer, null if default initialize to 0"

Which seems to indicate init() should return null if default initializer should be zero.  But a null array has length == 0.

I think the right solution to this is to change the documentation:

"Return default initializer.  If the type should be initialized to all zeros, an array with a null ptr and a length equal to the type size will be returned"

Sound good?

-- 
Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email
------- You are receiving this mail because: -------

http://d.puremagic.com/issues/show_bug.cgi?id=2990


Walter Bright <bugzilla@digitalmars.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bugzilla@digitalmars.com


--- Comment #2 from Walter Bright <bugzilla@digitalmars.com> 2011-04-05 11:31:07 PDT ---
This is deliberate, see the typinf.c code:

    // void[] init;
    dtsize_t(pdt, sd->structsize);       // init.length
    if (sd->zeroInit)
        dtsize_t(pdt, 0);                // NULL for 0 initialization
    else
        dtxoff(pdt, sd->toInitializer(), 0, TYnptr);    // init.ptr

I'll fix the documentation.

-- 
Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email
------- You are receiving this mail because: -------

http://d.puremagic.com/issues/show_bug.cgi?id=2990


Walter Bright <bugzilla@digitalmars.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|REOPENED                    |RESOLVED
         Resolution|                            |FIXED


--- Comment #3 from Walter Bright <bugzilla@digitalmars.com> 2011-04-05 11:41:20 PDT ---
https://github.com/D-Programming-Language/druntime/commit/a771c11bfe357ac2c6c87e96b39e8986286222f5

https://github.com/D-Programming-Language/phobos/commit/50a73bef9ac0e6f8bbc713c1ded85a8254175feb

-- 
Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email
------- You are receiving this mail because: -------