bug#30829: (no subject)

[Don Crissti]

Thanks for the prompt reply !
While I understand your explanation I think we are talking about slightly 
different things. Your example is different than mine. Let me re-write my code 
so as to be portable:
 
printf %s\\n 1 2 3 4 5 | sed -e '2,/5/{//!d' -e'}'

Now, as you can see, the main difference between my sample above and your sample

printf "%s\n" 1 2 3 4 5 | sed -n -e '2,/5/p' -e '//p'

is the braces (the command grouping). In other words, you are unconditionally 
using an empty regex while I'm only using it for lines that meet certain 
criteria. Based on your explanation (i.e. applied regex=executed regex, no 
executed regex=no previous regex on line 1 hence fail) I can understand why 
your code exits with error.

However, my code uses empty regex on condition (only for a certain range of 
lines). It is logical that '//!d' should not be executed for lines outside that 
range. If I used a plain 'd' instead of '//!d' would sed unconditionally delete 
all lines from the file ? No. It would delete only the lines in that range. 
Similarly, sed should not even attempt to evaluate the empty regex in '{//!d' 
for lines outside that range.

Unless I'm missing something I still see this as a bug.