Watch expression doesn't work properly

[Yegappan Lakshmanan]

Hi,

When a breakpoint is set on an expression, the breakpoint works sometimes

and doesn't work other times. For example, save the following code into

a file and source it:

let g:Count = 0
breakadd expr g:Count
func T()
  let g:Count += 1
endfunc
call T()
call T()
call T()

The breakpoint should be hit three times. But it is hit only twice and if some

other script runs later, then the breakpoint is hit. For example, after sourcing

the above script, try editing a file.

The has_watchexpr() function in debugger.c always returns 0. This problem

may be related to this. I see that in the original patch from Christian, the

debug_expr variable is incremented (https://github.com/vim/vim/pull/859).

in dbg_parsearg(). But in the latest Vim code, this variable is never incremented.

- Yegappan