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Re: Implicition declarations of functions and bugs

Steve Greenland <steveg@moregruel.net> writes:

> On 12-Mar-06, 04:22 (CST), Bastian Blank <waldi@debian.org> wrote: 
>> On Sat, Mar 11, 2006 at 01:43:34AM +0100, Samuel Thibault wrote:
>> > This is a warning and not an error, because using one's own strdup()
>> > function (that would take ints) is perfectly legal.
>> No, it is not. At least not with a compiler in hosted mode. In this
>> mode, the compiler is allowed to have any knowledge about the standard
>> library builtin. 
> Not if the relevant header hasn't been included. No "#include
> <string.h>", no compiler messing with "strdup()."

You are misinformed.  First, note that strdup() is not in the
standard C library, but it is in the reserved str* name space.
Declaring strdup() with external linkage *always* yields
undefined behavior.  Declaring strdup() with internal linkage
yields undefined behavior if <string.h> is included.  Read the

     7.1.3 Reserved identifiers


     - All identifiers with external linkage in any of the
        following subclauses (including the future library
        directions) are always reserved for use as identifiers
        with external linkage.154)

     - Each identifier with file scope listed in any of the
        following subclauses (including the future library
        directions) is reserved for use as a macro name and as an
        identifier with file scope in the same name space if any
        of its associated headers is included.


     7.26 Future library directions

1    The following names are grouped under individual headers for
     convenience.  All external names described below are
     reserved no matter what headers are included by the program.


     7.26.11 String handling <string.h>

1    Function names that begin with str, mem, or wcs and a lowercase
     letter may be added to the declarations in the <string.h>

"Writing is easy.
 All you do is sit in front of a typewriter and open a vein."
--Walter Smith

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