[Bug-apl] Assertion failure after reduction of empty array

[Kacper Gutowski]

Another one. Reduction of an empty array along the last non-singleton
AND non-zero axis produces a weird value which crashes GNU APL when
copied (e.g. when assigned to variable; nothing happens when it's simply
printed or directly examined with rank/depth/whatever):


      X ← +/[3] 0 0 2 0⍴ 0

==============================================================================
Assertion failed: 0
in Function:      init
in file:          Cell.cc:48

Call stack:

----------------------------------------
-- Stack trace at Cell.cc:48
----------------------------------------
0x7f06b6b2db45 __libc_start_main
0x435995  main
0x529e3d   Workspace::immediate_execution(bool)
0x4651cd    Command::process_line()
0x463f99     Command::process_line(UCS_string&)
0x46e678      Executable::execute_body() const
0x4e4360       StateIndicator::run()
0x49133a        Prefix::reduce_statements()
0x48d46e         Prefix::reduce_V_ASS_B_()
0x4f4a16          Symbol::assign(Value_P, char const*)
0x52652b           Value::clone(char const*) const
0x45b7c1            Cell::init(Cell const&)
0x443abf             do_Assert(char const*, char const*, char const*, int)
========================================

SI stack:

Depth:    0
Exec:     0x2105be0
Safe ex:  no
Pmode:    ◊  X ← +/[3] 0 0 2 0⍴ 0
PC:       10 ENDL
Stat:     X ← +/[3] 0 0 2 0⍴ 0
err_code: 0x0
thrown:   at StateIndicator.cc:41
e_msg_1:  'No Error'
e_msg_2:  ''
e_msg_3:  ''


==============================================================================


====================================================
SEGMENTATION FAULT

----------------------------------------
-- Stack trace at main.cc:122
----------------------------------------
0x7f06b6b2db45 __libc_start_main
0x435995  main
0x529e3d   Workspace::immediate_execution(bool)
0x4651cd    Command::process_line()
0x463f99     Command::process_line(UCS_string&)
0x46e678      Executable::execute_body() const
0x4e4360       StateIndicator::run()
0x49133a        Prefix::reduce_statements()
0x48d46e         Prefix::reduce_V_ASS_B_()
0x4f4a16          Symbol::assign(Value_P, char const*)
0x52652b           Value::clone(char const*) const
0x45b7c1            Cell::init(Cell const&)
0x443a67             do_Assert(char const*, char const*, char const*, int)
0x501a9c              TestFiles::assert_error()
0x7f06b8a84890               
0x47e22a                
========================================
====================================================


-k