[Bug c++/25546] New: Wrong-type destructor call accepted in template with no error

[steev at azuro dot com]

Hi all. g++ 3.4.4 seems to accept calling a destructor ~T() on a char * pointer
if you're inside a template in certain cases. Obviously not very serious in the
grand scheme of things! Apologies if this has been fixed - I couldn't find it
in the bug list, though.

--- START EXAMPLE ---
class Foo {};

struct Bing
{
  char *GetChar() { return new char; }
};

template<typename T> struct Bar
{
  void Wibble()
  {
    bing.GetChar()->~T(); // How can this be legal if T isn't char?
  }
  Bing bing; 
};

int main()
{
  Bar<Foo> fooBar;
  fooBar.Wibble();
}
--- END EXAMPLE ---

  You can see that the (char *) return from GetChar() has ~Foo() called on it,
but g++ 3.4.4 happily accepts this. It doesn't actually enter the destructor
for Foo - I guess it's calling the char destructor. If you split the call to
GetChar into "char *p = bing.GetChar(); p->~T();", then the compiler spots that
there's something wrong:

gccbug.cpp: In member function `void Bar<T>::Wibble() [with T = Foo]':
gccbug.cpp:21:   instantiated from here
gccbug.cpp:12: error: `*p' is not of type `Foo'

  Haven't tried it on g++ 3.4.5 or 4.0.x - I don't have time before Xmas
(sorry). Command line is "g++ -o gccbug gccbug.cpp", g++ -v gives:

Reading specs from
/space/azuro2/i686-pc-linux-gnu/toolset/lib/gcc/i686-pc-linux-gnu/3.4.4/specs
Configured with: ../gcc-3.4.4/configure --with-gnu-as --with-gnu-ld
--prefix=/space/azuro2/i686-pc-linux-gn/toolset -v : (reconfigured)
../gcc-3.4.4/configure --with-gnu-as --with-gnu-ld
--prefix=/space/azuro2/i686-pc-linux-gnu/toolset -v
Thread model: posix
gcc version 3.4.4

  Hope this helps. Have a good Xmas y'all, regards Steev


-- 
           Summary: Wrong-type destructor call accepted in template with no
                    error
           Product: gcc
           Version: 3.4.4
            Status: UNCONFIRMED
          Severity: minor
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: steev at azuro dot com
  GCC host triplet: i686-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25546