Re: f771 dies with trivial fortran code

[Jim Wilson <wilson@cygnus.com>]

This is due to a backend change made since gcc 2.7.2.

Some code was added to handle C++ destructors inside conditional expressions
differently than they used to be handled.  This apparently was necessary
for correct behaviour, though I don't know exactly what bug was being fixed.
(Perhaps destructors were always run, even if the variable was only constructed
on one side of the conditional expression?)

Anyways, this causes problems if a conditional expression appears inside
the type expression of a parameter.  The code expects us to always have
a binding contour, but we do not have one when parsing the parameters.
Since no destructors are possible in this case, it is safe for us to
do nothing.

A C testcase:

sub (int a, int b, int c[a > b ? a : b])
{
}

A Fortran testcase:

	subroutine foo ()
	character*(*) str
c
	return
c
	entry bar (str)
	str = 'a'
c	^^^^^^^^ culprit
	return
	end
c

I have checked in this patch to fix the problem.

Wed Aug 20 11:58:33 1997  Jim Wilson  <wilson@cygnus.com>

	* stmt.c (start_cleanup_deferal, end_cleanup_deferal): Test
	block_stack before dereferencing it.

Index: stmt.c
===================================================================
RCS file: /cvs/cvsfiles/egcs/stmt.c,v
retrieving revision 1.1.1.1
diff -p -r1.1.1.1 stmt.c
*** stmt.c	1997/08/11 15:57:13	1.1.1.1
--- stmt.c	1997/08/20 18:43:30
*************** expand_cleanups (list, dont_do, in_fixup
*** 4212,4218 ****
  void
  start_cleanup_deferal ()
  {
!   ++block_stack->data.block.conditional_code;
  }
  
  /* Mark the end of a conditional region of code.  Because cleanup
--- 4212,4221 ----
  void
  start_cleanup_deferal ()
  {
!   /* block_stack can be NULL if we are inside the parameter list.  It is
!      OK to do nothing, because cleanups aren't possible here.  */
!   if (block_stack)
!     ++block_stack->data.block.conditional_code;
  }
  
  /* Mark the end of a conditional region of code.  Because cleanup
*************** start_cleanup_deferal ()
*** 4223,4229 ****
  void
  end_cleanup_deferal ()
  {
!   --block_stack->data.block.conditional_code;
  }
  
  /* Move all cleanups from the current block_stack
--- 4226,4235 ----
  void
  end_cleanup_deferal ()
  {
!   /* block_stack can be NULL if we are inside the parameter list.  It is
!      OK to do nothing, because cleanups aren't possible here.  */
!   if (block_stack)
!     --block_stack->data.block.conditional_code;
  }
  
  /* Move all cleanups from the current block_stack