Re: [bug-gawk] 'watch' in gawk debugger gives wrong NR

[Aharon Robbins]

Hi.

Thanks for your note. Here is what I got when I tried your example
using the gawk-4.1-stable branch in git.  I don't think there's
a bug.

Run gawk:

| Script started on Mon Nov 23 20:56:29 2015
| [aahz:pts/6 gawk.git]$ ./gawk -D -f testprog.awk data.in

List:

| gawk> list
| 1       #! /usr/bin/gawk -f
| 2       BEGIN {
| 3            c = 0
| 4       }
| 5       
| 6       /apple/ {
| 7            nr = NR
| 8            c++
| 9            # printf "[c, NR] = [%s, %s]\n", c, NR
| 10      }
| 11      
| 12      END {
| 13          print c
| 14      }

Setup watchpoints, display variables, and breakpoint:

| gawk> watch c
| Watchpoint 1: c
| gawk> display nr
| 1: nr = untyped variable
| gawk> display NR
| 2: NR = 0
| gawk> display c
| 3: c = untyped variable
| gawk> break 6
| Breakpoint 2 set at file `testprog.awk', line 6

Run!

| gawk> run
| Starting program: 
| Stopping in Rule ...
| Breakpoint 2, main() at `testprog.awk':6
| 6       /apple/ {
| 1: nr = untyped variable
| 2: NR = 1
| 3: c = 0
| gawk> print $0
| $0 = "1 1 pear"

So far, so good. First record doesn't match, nr has not been assigned
to, and NR is correct.

| gawk> continue
| Watchpoint 1: c
|   Old value: untyped variable
|   New value: 0

Hmm. This is a little strange. Maybe I need to look at why the
watchpoint was triggered.

| main() at `testprog.awk':6
| 6       /apple/ {
| 1: nr = untyped variable
| 2: NR = 1
| 3: c = 0
| gawk> print $0
| $0 = "1 1 pear"

So, we're still in the first record. NR is ok.

| gawk> continue
| Breakpoint 2, main() at `testprog.awk':6
| 6       /apple/ {
| 1: nr = untyped variable
| 2: NR = 2
| 3: c = 0
| gawk> print $0
| $0 = "2 1 apple 4"

Continue on:

| gawk> continue
| Breakpoint 2, main() at `testprog.awk':6
| 6       /apple/ {
| 1: nr = 2
| 2: NR = 3
| 3: c = 1
| gawk> print $0
| $0 = "3 2 pear"

We're at record 3. It won't match, but NR is displayed correctly.

| gawk> exit
| error: unknown command - "exit", try help
| gawk> ^D

I think display of NR is OK.  I probably need to figure out
why the watchpoint triggered.

Thanks,

Arnold