Use CLEANUP_POINT_EXPR for auto-destructing temporaries.

[ibuclaw]

Another example moving lowering from frontend (glue) to gimple.

Puts declarations marked needsScopeDtor into a TARGET_EXPR, i.e:

TARGET_EXPR <__pfx79,  // decl
             *__ctor (&__pfx79, 0), // init
             __dtor (&__pfx79), // cleanup>;

Then _build_expr_dtor wraps up the result into a CLEANUP_POINT_EXPR, e.g:

<<cleanup_point
  TARGET_EXPR <__pfx79, *__ctor (&__pfx79, 0)>;
  some_func (&__pfx79);>>;

The gimplification of cleanup_point_expr nodes then adds try/finally as needed for us, in the correct order. i.e:

try
{
  __pfx79 = *__ctor (&__pfx79, 0);
  try
  {
    some_func (&__pfx79); // may throw
  }
  finally
  {
    __dtor (&__pfx79);
  }
}
finally
{
  __pfx79 = {CLOBBER};  // constructor maybe threw.
}

Fixes broken test in test14903.d.

[ibuclaw]

Fixes broken test in test14903.d.

And causes a regression in another (sdtor.d / issue 13095)

[ibuclaw]

Should be sorted now.

[jpf91]

👍