390 diagnostic warnings, deprecations, errors in perl 5.002b3 Feb 03, 1996: 
perl -MHTTP::Tiny -le'$|++;for(split/\n/,HTTP::Tiny->new->get("https:/
+/fastapi.metacpan.org/source/LWALL/perl5.002b3/pod/perldiag.pod")->{c
+ontent}){print${1}and$-++if/^=item\s+(\S\S.*)$/}print(($-+1)," diagno
+stic warnings, deprecations, errors in perl 5.002b3 Feb 03, 1996")'

[download]
1104 diagnostic warnings, deprecations, errors in perl v5.42.0 Compiled at Dec 17 2025: 
perl -MConfig=compile_date -le'$|++;for(`perldoc -u perldiag`){print${
+1}and$-++if/^=item\s+(\S\S.*)$/}print(($-+1)," diagnostic warnings, d
+eprecations, errors in perl $^V ").compile_date()'

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What is forbidden? 
perl -MConfig=compile_date -le'$|++;for(`perldoc -u perldiag`){print${
+1}and$-++if/^=item\s+(\S\S.*)$/}print(($-+1)," diagnostic warnings, d
+eprecations, errors in perl $^V ").compile_date()' | grep 'forbidden'

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Experimental %s on scalar is now forbidden
Initialization of state variables in list currently forbidden
Setting $/ to a reference to %s is forbidden
Setting $/ to %s reference is forbidden
Use of bare << to mean <<"" is forbidden
Use of strings with code points over 0xFF as arguments to vec is forbidden

In reply to diagnostics: warning, deprecation, error by Anonymous Monk

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