What should the appended program print?  Four different compilers
give four different results.

The result of the conditional expression is an rvalue, either
  - an rvalue referring to the static object s
  - an rvalue referring to a temporary object

Visual C++ 6.0 copy-constructs a reference-lifetime temporary
in both cases.  In the 'true' case it also constructs an
expression-lifetime temporary.  This would seem to correspond
to reference-binding to rvalues being implementation-defined
(as per the choice in 8.5.3#5) to use a temporary.

g++ 3.1 on the other hand constructs only a reference-lifetime
temporary.  In the 'true' case this is the temporary in one
side of the conditional ("temp"); there is no copy-construction.
In the 'false' case the reference is bound to a separate object
copy-constructed from the static object.  Is that allowed or
must it always make the same choice?

struct S {
  S(char const *name = "def"): str(name) { printf("con %s\n", name); }
  S(S const &s): str("copy") { printf("copy %s\n", s.str); }
  ~S() { printf("des %s\n", str); str = "*dead*"; }
  void show(void) const { printf("show %s\n", str); }
  char const *str;
};

S s("stat");

int f(bool n) {
  printf("call %d\n", n);
  S const &r = n ? S("temp") : s;
  r.show();
  printf("body\n");
  return 0;
}

int main(int argc, char **argv) { f(true); f(false); return 0; }

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