Re: Why is the error thrown from close(FH) when the error is the missing <> on while(FH)? ( line number mismatch, look above, look before )(Bareword found in conditional)

My question is: Why is the error not thrown from the while on 83?

It is, it just doesn't say line 83, the line number is wrong, it is a mismatch, example

$ cat junk
while( STDIN ){
    @ARGV=2;
}
# 4
# 5
$ perl -w -Mstrict junk
Bareword "STDIN" not allowed while "strict subs" in use at junk line 5
+.
Execution of junk aborted due to compilation errors.
[download]

$ cat junk
while( STDIN ){
    @ARGV=2;
}
[download]

I vaguely remember when I first learned to always look at the earliest error message, start at the reported line number, and look before, look above -- this is especially true in perl :)

But you've found a new bug in strict.pm, consider

 $ cat junk
while( STDIN ){
    @ARGV=2;
}
close STDIN;
[download]

With strict the following error message is misleading

$ perl -Mstrict junk
Bareword "STDIN" not allowed while "strict subs" in use at junk line 4
+.
Execution of junk aborted due to compilation errors.
[download]

If you look at line 4, you'll see close STDIN, but we know close takes barewords -- it can be very confusing even if you know to look above

But with warnings the error message is more informative

$ perl -w junk
Bareword found in conditional at junk line 4.
Terminating on signal SIGINT(2)
[download]

Sure, the line number is wrong (and the program runs forever, infinite loop is infinite), but we know close STDIN; is not a conditional , so there is less confusion

OTOH :) here is where the advantage falls apart , a conditional close STDIN if fileno STDIN; or fileno STDIN and close STDIN;

so warnings can detect a bareword in a conditional, strict can name the bareword, strict should say it is in a conditional, its more informative

On the history of the line number bug
Warning gets the line number wrong?
Error messages point to wrong line number in if-elsif construct,
if-elsif weirdness,
No Pause on Elsif in Debugger
https://rt.perl.org/rt3//Public/Search/Simple.html?q=perl5+line+number
#1031: Incorrect line number reporting due to overoptimization
#1034: error line number reported wrong when using here documents
#7084: "Use of uninitialized value" reported on incorrect line number
#8051: -B wrong line number after die
#47632: Undef loop while condition, loop code motion, and bad warning line number? 5.10-RC1 + 5.8.8
#70910: wrong line number in syntax error message
#114070: here-docs cause bogus line numbers
#115768: wrong line number in error message

:) Perl gets the line number right in the beginning (: (see "junk:" below)

$ cat junk
while( STDIN ){
    @ARGV=@ARGV;
}
close STDIN ;
$ perl -MO=Concise junk
h  <@> leave[1 ref] vKP/REFC ->(end)
1     <0> enter ->2
2     <;> nextstate(main 3 junk:1) v:{ ->3
d     <2> leaveloop vK/2 ->e
3        <{> enterloop(next->c last->d redo->4) v ->4
-        <@> lineseq vK ->d
4           <;> nextstate(main 1 junk:2) v ->5
b           <2> aassign[t6] vKS/COMMON ->c
-              <1> ex-list lK ->8
5                 <0> pushmark s ->6
7                 <1> rv2av[t5] lK/1 ->8
6                    <#> gv[*ARGV] s ->7
-              <1> ex-list lK ->b
8                 <0> pushmark s ->9
a                 <1> rv2av[t3] lKRM*/1 ->b
9                    <#> gv[*ARGV] s ->a
c           <0> unstack v ->4
e     <;> nextstate(main 3 junk:4) v:{ ->f
g     <1> close vK/1 ->h
f        <#> gv[*STDIN] s ->g
junk syntax OK
[download]

update: :) I acknowledge kcott beat me to the punch , I mean he struck first, I mean I'm not a violent person at all, its just an expression, he posted first :p

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