variables not shown in single stepping

[Denis Budyak]

SBCL 1.4.2 on Debian 3.16.39-1/Amd64 or SBCL 1.3.18 at Win10/Amd64 have the following issue:

;; file variables-not-shown-in-single-stepping.lisp

(declaim (optimize (speed 0) (debug 3) (safety 3) (space 0) (compilation-speed 0)))

(defun gg (y) y)

(defun ff (x)
  (let ((y (+ x 1))
        (z (- x 1)))
    ;(sb-impl::enable-stepping) ;; the same, but faster
    (break)
    (list
     (gg y)
     (+ z y)
     )))
;; EOF

The following is a procedure to reproduce:
* *features*
(:64-BIT :64-BIT-REGISTERS :ALIEN-CALLBACKS :ANSI-CL :ASH-RIGHT-VOPS
 :C-STACK-IS-CONTROL-STACK :COMMON-LISP :COMPACT-INSTANCE-HEADER
 :COMPARE-AND-SWAP-VOPS :COMPLEX-FLOAT-VOPS :CYCLE-COUNTER :ELF :FLOAT-EQL-VOPS
 :FP-AND-PC-STANDARD-SAVE :GENCGC :IEEE-FLOATING-POINT :IMMOBILE-CODE
 :IMMOBILE-SPACE :INLINE-CONSTANTS :INTEGER-EQL-VOP :LARGEFILE :LINKAGE-TABLE
 :LINUX :LITTLE-ENDIAN :MEMORY-BARRIER-VOPS :MULTIPLY-HIGH-VOPS
 :OS-PROVIDES-BLKSIZE-T :OS-PROVIDES-DLADDR :OS-PROVIDES-DLOPEN
 :OS-PROVIDES-GETPROTOBY-R :OS-PROVIDES-POLL :OS-PROVIDES-PUTWC
 :OS-PROVIDES-SUSECONDS-T :PACKAGE-LOCAL-NICKNAMES :PRECISE-ARG-COUNT-ERROR
 :RAW-INSTANCE-INIT-VOPS :RAW-SIGNED-WORD :RELOCATABLE-HEAP :SB-AFTER-XC-CORE
 :SB-DOC :SB-EVAL :SB-FLUID :SB-FUTEX :SB-LDB :SB-PACKAGE-LOCKS :SB-SIMD-PACK
 :SB-SOURCE-LOCATIONS :SB-THREAD :SB-UNICODE :SB-XREF-FOR-INTERNALS :SBCL
 :STACK-ALLOCATABLE-CLOSURES :STACK-ALLOCATABLE-FIXED-OBJECTS
 :STACK-ALLOCATABLE-LISTS :STACK-ALLOCATABLE-VECTORS
 :STACK-GROWS-DOWNWARD-NOT-UPWARD :SYMBOL-INFO-VOPS :UNBIND-N-VOP
 :UNDEFINED-FUN-RESTARTS :UNIX :UNWIND-TO-FRAME-AND-CALL-VOP :X86-64)

* (load (compile-file "variables-not-shown-in-single-stepping.lisp"))
* (ff 5)

debugger invoked on a SIMPLE-CONDITION in thread
#<THREAD "main thread" RUNNING {1001E500C3}>:
  break

Type HELP for debugger help, or (SB-EXT:EXIT) to exit from SBCL.

restarts (invokable by number or by possibly-abbreviated name):
  0: [CONTINUE] Return from BREAK.
  1: [ABORT ] Exit debugger, returning to top level.

(FF 5)
   source: (BREAK)
0] start
; Evaluating call:
; (GG Y)
; With arguments:
; 6

1] l
X = 5
Y = 6
Z = 4

1] next
; Evaluating call:
; (+ Z Y)
; With unknown arguments

0] l
X = 5

That is the issue: Y and Z are not shown.

[Denis Budyak (budden73)]

It might be another bug than #1274103. If we place (break) near the same place, all variables are shown.