Is it true that ($match){1}+ equals to simply $match? Yes, and the + does nothing here, as you can see with use warnings:

That's only true because you the OP included a quantifier in the embedded regex; and you get 3 fails because your anchors guarantee the regex used couldn't succeed (which doesn't seem like a useful test?)

This shows that {n}+ is a valid quantifier:

use strict;
use warnings;

chomp(my $match = <DATA>);
chomp(   $_     = <DATA>);

for my $regex (
                  "($match){1}+",
                  "($match){1}",
                  "($match)",
                  "($match)+",
                  "($match)+?",
              )
{
    print qw(FAIL SUCCESS)[ !! m/$regex/ ], "\n"
}

__DATA__
(?:a|b)
bbab
[download]

C:\test>junk37
SUCCESS
SUCCESS
SUCCESS
SUCCESS
SUCCESS
[download]

Hello BrowserUk,

I still get the warning when the regex isn’t embedded:

23:15 >perl -wE "my $r = qr{(?:a|b)}; say $r;"
(?^u:(?:a|b))

23:17 >perl -wE "my $r = qr{(?:a|b){1}}; say $r;"
(?^u:(?:a|b){1})

23:17 >perl -wE "my $r = qr{(?:a|b){1}+}; say $r;"
Useless use of greediness modifier '+' in regex; marked by <-- HERE in
+ m/(?:a|b){1}+ <-- HERE / at -e line 1.
(?^u:(?:a|b){1}+)

23:17 >perl -v

This is perl 5, version 22, subversion 0 (v5.22.0) built for MSWin32-x
+64-multi-thread
...
[download]

I get the same warning with Strawberry Perl v5.20.2, but not with v5.18.2. Is the warning erroneous?

Athanasius <°(((>< contra mundum

Iustus alius egestas vitae, eros Piratica,

I get the same warning with Strawberry Perl v5.20.2, but not on v5.18.2.

You're right! My default perl is currently 5.18:

C:\test>\perl5.18\perl\bin\perl.exe junk37.pl
SUCCESS
SUCCESS
SUCCESS
SUCCESS
SUCCESS

C:\test>\Perl5.20\bin\perl.exe junk37.pl
Useless use of greediness modifier '+' in regex; marked by <-- HERE in
+ m/((?:a|b)){1}+ <-- HERE / at junk37.pl line 15, <DATA> line 2.
SUCCESS
SUCCESS
SUCCESS
SUCCESS
SUCCESS

C:\test>\Perl22\bin\perl.exe junk37.pl
Useless use of greediness modifier '+' in regex; marked by <-- HERE in
+ m/((?:a|b)){1}+ <-- HERE / at junk37.pl line 15, <DATA> line 2.
SUCCESS
SUCCESS
SUCCESS
SUCCESS
SUCCESS
[download]

Is the warning erroneous?

Erm. I was relying on Perl to tell me :)

The fact that the warning has been recently added suggests it is probably correct.

That said, the construct is still listed in the 5.22 docs:  {n}+   Match exactly n times and give nothing back (redundant); which basically means your guess is as good as anybody's at this point?

---

With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

"Science is about questioning the status quo. Questioning authority". I knew I was on the right track :)

In the absence of evidence, opinion is indistinguishable from prejudice.

I'm with torvalds on this Agile (and TDD) debunked I told'em LLVM was the way to go. But did they listen!

> Is the warning erroneous?

if the meaning of {n}+ hasn't be deprecated or changed its a totally wrong warning.

Please run my code with 5.20, with same results we should file a bug report.

edit

As you can see there its not redundant.

The plus is neither a greedyness operator here, bc its in second place, its there to stop backtracking.

update

Apparently adding the second + turns the whole quantifier {n}+ into a possessive quantifier.

see here

Like a greedy quantifier, a possessive quantifier repeats the token as many times as possible. Unlike a greedy quantifier, it does not give up matches as the engine backtracks. With a possessive quantifier, the deal is all or nothing. You can make a quantifier possessive by placing an extra + after it. * is greedy, *? is lazy, and *+ is possessive. ++, ?+ and {n,m}+ are all possessive as well.

so + is "greedy" and ++ "possessive", {n}+ is analogous to ++ .

Cheers Rolf
_{(addicted to the Perl Programming Language and ☆☆☆☆ :)
Je suis Charlie!}