Unwind-only stack overflow exceptions

* module/ice-9/boot-9.scm (catch): Signal an early error if the handler
  or pre-unwind handler types aren't right.  This is more important than
  it was, given that we dispatch on type now when finding matching catch
  clauses.

* libguile/vm.c (vm_expand_stack): Use the standard
  scm_report_stack_overflow to signal stack overflow.  This will avoid
  running pre-unwind handlers.

* libguile/throw.h: Move scm_report_stack_overflow here.

* libguile/throw.c (catch): Define a version of catch in C.
  (throw_without_pre_unwind): New helper.  Besides serving as the
  pre-boot "throw" binding, it allows stack overflow to throw without
  running pre-unwind handlers.
  (scm_catch, scm_catch_with_pre_unwind_handler)
  (scm_with_throw_handler): Use the new catch in C.
  (scm_report_stack_overflow): Moved from stackchk.c; throws an
  unwind-only exception.

* libguile/stackchk.h:
* libguile/stackchk.c: Remove the scm_report_stack_overflow bits.

1 files changed, 3 insertions, 7 deletions

diff --git a/libguile/vm.c b/libguile/vm.c
index b071a54cb..db1309432 100644
--- a/libguile/vm.c
+++ b/libguile/vm.c
@@ -1016,13 +1016,7 @@ vm_expand_stack (struct scm_vm *vp)
       old_stack = vp->stack_base;
       new_stack = expand_stack (vp->stack_base, vp->stack_size, new_size);
       if (!new_stack)
-        /* It would be nice to throw an exception here, but that is
-           extraordinarily hard.  Exceptionally hard, you might say!
-           "throw" is implemented in Scheme, and there may be arbitrary
-           pre-unwind handlers that push on more frames.  We will
-           endeavor to do so in the future, but for now we just
-           abort.  */
-        abort ();
+        scm_report_stack_overflow ();
 
       vp->stack_base = new_stack;
       vp->stack_size = new_size;
@@ -1068,6 +1062,8 @@ vm_expand_stack (struct scm_vm *vp)
       /* Finally, reset the limit, to catch further overflows.  */
       vp->stack_limit = vp->stack_base + vp->max_stack_size;
 
+      /* FIXME: Use scm_report_stack_overflow, but in a mode that allows
+         pre-unwind handlers to run.  */
       vm_error ("VM: Stack overflow", SCM_UNDEFINED);
     }