Package: perl
Version: 5.8.7-4
Tags: upstream
When square or round brackets are used as regular expression delimiters,
the expression apparently cannot contain a backslash-escaped literal
opening delimiter bracket.
I see nothing in the documentation to suggest that this is intentional
or expected behavior.
vnix$ $ perl -ne 'print if m(\()' </dev/null
Unmatched ( in regex; marked by <-- HERE in m/( <-- HERE / at -e line
1.
vnix$ perl -ne 'print if m[\[]' </dev/null
Unmatched [ in regex; marked by <-- HERE in m/[ <-- HERE / at -e line
1.
Note that in the error message, the backslash is missing.
The closing square bracket works as expected:
vnix$ perl -ne 'print if m[\]]' </dev/null
But with the rounded parens, the closing paren too is mishandled:
vnix$ perl -ne 'print if m(\))' </dev/null
Unmatched ) in regex; marked by <-- HERE in m/) <-- HERE / at -e line
1.
With square brackets, you get an error message even if there is an
escaped pair:
vnix$ perl -ne 'print if m[\[\]]' </dev/null
Unmatched [ in regex; marked by <-- HERE in m/[ <-- HERE ]/ at -e line
1.
If you remove the escape from the closing square bracket, you still get
the error:
vnix$ perl -ne 'print if m[\[]]' </dev/null
Unmatched [ in regex; marked by <-- HERE in m/[ <-- HERE / at -e line
1.
Also note that the error message lacks the closing square bracket.
With rounded brackets, matching pairs work as expected:
vnix$ echo 'foo()' | perl -ne 'print if m(\(\))'
foo()
Curly brackets and brokets work fine:
vnix$ perl -ne 'print if m{\{}' </dev/null
vnix$ perl -ne 'print if m<\<>' </dev/null
I'm afraid I don't have the means to test this with other versions of
Perl at the moment.
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