[Bug c++/44148] New: C++ genericization/gimplification may clobber templare arguments

["jakub at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

template <typename T> struct S2
{
  typedef const T &t2;
  t2 operator* () const {}
};
template <typename T> struct S3
{
  typedef S2 <T> t5;
};
template <typename T1, typename T2> T2 foo1 (T1 x, T2 y) { y (*x); }
template <class T> struct S4
{
  T &operator* () const;
};
struct S7 {};
struct S8
{
  typedef::S3 <S4 <S7> >::t5 t6;
  t6 m1 () const;
};
template <class T> struct S9
{
  typedef T t3;
  inline t3 &operator[] (unsigned int) {}
};
template <typename T1, typename T2, typename T3, void (&T4) (const T1 &, T3 &)>
struct S10
{
  S10 (T2 & x, unsigned int y = 0) : u (x), v (y) {}
  void operator () (const S4 <T1> &x) { T4 (*x, u[v++]); }
  T2 &u;
  unsigned int v;
};
struct S15;
struct S11
{
  static void m3 (const S8 &, S15 &);
};
struct S16;
struct S12;
struct S13
{
  static void m4 (const S7 & desc,S16 & toconfig);
};
typedef S10 <S7, S12, S16, S13::m4> t10;
struct S12: S9 <S16>
{
};
struct S15
{
  S12 p;
};
void S11::m3 (const S8 & x, S15 &y)
{
  foo1 (x.m1 (), t10 (y.p));
}

ICEs with -fpic on x86_64-linux on redhat/gcc-4_4-branch.  While it works
on the trunk, I believe this is a latent problem there.

The issue is that a template argument (<nop_expr <addr_expr <baselink...> > >)
is not unshared, so instantiated code can reference those trees and C++
genericization/gimplification then actually modifies not just the function
code, but also the template arguments.  If anything from the template is later
on mangled, the mangling is different (<baselink ...> is replaced by
<function_decl ...>).


-- 
           Summary: C++ genericization/gimplification may clobber templare
                    arguments
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: jakub at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44148