*** Bug 30993 has been marked as a duplicate of this bug. ***

Confirmed, a regression from 3.3.3.  I made sure in 3.3.3, we would warn about the function if we removed the attribute noreturn so I know the warning works for that case.

This is somewhat complicated. 
The extra type cast causes
different code paths to be taken.
In particular, in finish_call_expr() in cp/semantics.c:

  if (processing_template_decl)
    {
      if (type_dependent_expression_p (fn)
          || any_type_dependent_arguments_p (args))
        {
          result = build_nt_call_list (fn, args);
          KOENIG_LOOKUP_P (result) = koenig_p;
          return result;
        }
      if (!BASELINK_P (fn)
          && TREE_CODE (fn) != PSEUDO_DTOR_EXPR
          && TREE_TYPE (fn) != unknown_type_node)
        fn = build_non_dependent_expr (fn);
      args = build_non_dependent_args (orig_args);



With the type cast, 
build_over_call() is called eventually
which checks TREE_THIS_VOLATILE() for the callee function decl
and mark the current function (i.e. caller A::g) as returns_abnormally.
The lack of the type cast triggers
any_type_dependent_arguments_p(args) above,
leading to build_nt_call_list() which doesn't do this marking
of the returns_abnormally.

Now, not being familiar with the c++ frontend,
I'm not sure where exactly we should do the checking
of TREE_THIS_VOLATILE() for the callee decl.

The following patch seems to fix the problem 
(though I can't even tell whether this is the right approach):

diff -r 15a559a8fcf0 gcc/cp/semantics.c
--- a/gcc/cp/semantics.c        Mon Mar 12 15:38:22 2007 -0700
+++ b/gcc/cp/semantics.c        Tue Mar 13 15:48:45 2007 -0700
@@ -1816,6 +1816,10 @@ finish_call_expr (tree fn, tree args, bo
          || any_type_dependent_arguments_p (args))
        {
          result = build_nt_call_list (fn, args);
+
+         if (fn && TREE_THIS_VOLATILE (fn) && cfun)
+           current_function_returns_abnormally = 1;
+
          KOENIG_LOOKUP_P (result) = koenig_p;
          return result;
        }

IMNSHO this is not a regression.
void f (const char *)
#ifdef NORET
__attribute__ ((noreturn))
#endif
;

template <class T> struct A
{
  int g ()
  {
#ifdef TEST1
    f (__FUNCTION__);
#elif defined TEST2
    f ((const char*) __FUNCTION__);
#else
    f ((const char *) 0);
#endif
  }
};

for k in gcc-2.96-rh gcc-3.2 gcc-3.3 gcc-3.4 gcc-4.1 gcc-4.2 gcc-4.3; do for i in " -DNORET" ""; do \
  for j in -DTEST1 -DTEST3 -DTEST3; do \
    /usr/src/$k/obj/gcc/cc1plus $i $j pr30988.C -O3 -Wall -quiet 2>&1 \
      | sed -n "/warning:/s/^/$k$i $j /p"; done; done; done
gcc-3.2 -DNORET -DTEST1 pr30988.C:18: warning: no return statement in function returning non-void
gcc-3.2 -DNORET -DTEST3 pr30988.C:18: warning: no return statement in function returning non-void
gcc-3.2 -DNORET -DTEST3 pr30988.C:18: warning: no return statement in function returning non-void
gcc-3.2 -DTEST1 pr30988.C:18: warning: no return statement in function returning non-void
gcc-3.2 -DTEST3 pr30988.C:18: warning: no return statement in function returning non-void
gcc-3.2 -DTEST3 pr30988.C:18: warning: no return statement in function returning non-void
gcc-3.4 -DNORET -DTEST1 pr30988.C:18: warning: no return statement in function returning non-void
gcc-3.4 -DTEST1 pr30988.C:18: warning: no return statement in function returning non-void
gcc-3.4 -DTEST3 pr30988.C:18: warning: no return statement in function returning non-void
gcc-3.4 -DTEST3 pr30988.C:18: warning: no return statement in function returning non-void
gcc-4.1 -DNORET -DTEST1 pr30988.C:18: warning: no return statement in function returning non-void
gcc-4.1 -DTEST1 pr30988.C:18: warning: no return statement in function returning non-void
gcc-4.1 -DTEST3 pr30988.C:18: warning: no return statement in function returning non-void
gcc-4.1 -DTEST3 pr30988.C:18: warning: no return statement in function returning non-void
gcc-4.2 -DNORET -DTEST1 pr30988.C:18: warning: no return statement in function returning non-void
gcc-4.2 -DTEST1 pr30988.C:18: warning: no return statement in function returning non-void
gcc-4.2 -DTEST3 pr30988.C:18: warning: no return statement in function returning non-void
gcc-4.2 -DTEST3 pr30988.C:18: warning: no return statement in function returning non-void
gcc-4.3 -DNORET -DTEST1 pr30988.C:18: warning: no return statement in function returning non-void
gcc-4.3 -DTEST1 pr30988.C:18: warning: no return statement in function returning non-void
gcc-4.3 -DTEST3 pr30988.C:18: warning: no return statement in function returning non-void
gcc-4.3 -DTEST3 pr30988.C:18: warning: no return statement in function returning non-void

So, gcc-2.96-RH and 3.3 wouldn't warn ever in templates, even for cases where it should warn, e.g. when the argument is not type dependent and neither the called function has noreturn attribute.

Oops, sorry for the typo (twice -DTEST3, never -DTEST2).  But with -DTEST2 the output is always identical to -DTEST3 with all compilers.

Subject: Bug 30988

Author: jakub
Date: Sun Nov 18 22:20:54 2007
New Revision: 130280

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=130280
Log:
	PR c++/30988
	semantics.c (finish_call_expr): Set current_function_returns_abnormally
	if fn is noreturn FUNCTION_DECL or OVERLOAD with all noreturn
	functions.

	* g++.dg/warn/noreturn-4.C: New test.
	* g++.dg/warn/noreturn-5.C: New test.
	* g++.dg/warn/noreturn-6.C: New test.
	* g++.dg/warn/noreturn-7.C: New test.

Added:
    trunk/gcc/testsuite/g++.dg/warn/noreturn-4.C
    trunk/gcc/testsuite/g++.dg/warn/noreturn-5.C
    trunk/gcc/testsuite/g++.dg/warn/noreturn-6.C
    trunk/gcc/testsuite/g++.dg/warn/noreturn-7.C
Modified:
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/semantics.c
    trunk/gcc/testsuite/ChangeLog

Fixed on the trunk.

Closing 4.1 branch.

Closing 4.2 branch, fixed in 4.3.

(In reply to comment #9)
> Closing 4.2 branch, fixed in 4.3.

Thanks!