This is the mail archive of the gcc@gcc.gnu.org mailing list for the GCC project.

Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Re: Compiling GCC With a C++ Compiler (g++)


On 12/10/2004, at 8:42 PM, Gabriel Dos Reis wrote:

The code in build_string

  memset (s, 0, sizeof (struct tree_common));
  TREE_SET_CODE (s, STRING_CST);
  TREE_STRING_LENGTH (s) = len;
  memcpy ((char *) TREE_STRING_POINTER (s), str, len);
  ((char *) TREE_STRING_POINTER (s))[len] = '\0';

is trying to do similar thing, but it is undefined behaviour.

       [#5] If an attempt is made to modify an object defined  with
       a  const-qualified  type  through use of an lvalue with non-
       const-qualified type, the  behavior  is  undefined.

The object here is '*s', which was not defined with a const-qualified type. It's not defined with any type at all, it was allocated through malloc which is not a typed interface. (It would be different if it was allocated through 'new', but we do not have new in C.)

Attachment: smime.p7s
Description: S/MIME cryptographic signature

Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]