* libguile/dynstack.h:
* libguile/dynstack.c (scm_dynstack_find_old_fluid_value): New
function.
* libguile/fluids.c (saved_dynamic_state_ref): New helper.
(scm_fluid_ref): Fix docstring.
(scm_fluid_ref_star): New function allowing access to previous values
for a fluid.
(scm_dynamic_state_ref): New internal function.
* libguile/fluids.h: Add scm_fluid_ref_star and scm_dynamic_state_ref.
* libguile/stacks.c (scm_stack_id): Adapt to %stacks not being a chain.
* libguile/throw.c (catch, throw_without_pre_unwind): Adapt to
%exception-handlers not being a chain.
* module/ice-9/boot-9.scm (catch, dispatch-exception): Instead of having
%exception-handlers be a chain, use fluid-ref* to access the chain
that is in place at the time the exception is thrown. Prevents
unintended undelimited capture of the current exception handler stack
by a delimited "catch".
(%start-stack): Similarly, don't be a chain.
* module/system/repl/debug.scm (frame->stack-vector):
* module/system/repl/error-handling.scm (call-with-error-handling):
* module/ice-9/save-stack.scm (save-stack): Adapt to %stacks not being a
chain.
* test-suite/tests/exceptions.test ("delimited exception handlers"): Add
tests.
* doc/ref/api-control.texi (Fluids and Dynamic States): Add docs.
* module/ice-9/scm-style-repl.scm:
* module/ice-9/save-stack.scm: As the deprecated bindings have been
removed from the default environment, use #:export instead of
#:replace.
* libguile/backtrace.h (scm_the_last_stack_fluid_var)
* libguile/backtrace.c (scm_init_backtrace): No more
scm_the_last_stack_fluid_var. The replacement is to resolve
`the-last-stack' in (ice-9 stack-catch).
(scm_backtrace_with_highlights): Accordingly, instead of backtracing
the last stack, backtrace the current stack.
* libguile/throw.h:
* libguile/throw.c:
* libguile/deprecated.h:
* libguile/deprecated.c (scm_internal_stack_catch): Deprecate this
function.
* module/ice-9/save-stack.scm (the-last-stack): Move here from boot-9.
* module/ice-9/debug.scm:
* module/ice-9/debugger.scm: Use (ice-9 save-stack) for the-last-stack.
* module/ice-9/deprecated.scm (the-last-stack): Add deprecated shim.
