I wondered what would happen if one were to use all core modules. Here's what happened:

19 core libs can not be simply used, without being fatal, so they're commented out (ymmv on versions ne 5.26.2).

The perl interpreter grows to about 150 megabytes.

A series of warnings is printed which may or may not have any value. This is why I'm sharing it here. In case the warnings indicate real issues, or interesting things to investigate.

This 1-liner generates the ~650 line script, redirects stdout to the file "useallcore" and runs "perl useallcore" which prints the errors, and lines from ps about the perl process.

perl -MExtUtils::Installed -MModule::Metadata -e '$not=q/_charnames|au
+touse|blib|charnames|Devel::Peek|encoding|encoding::warnings|feature|
+File::Spec::VMS|filetest|GDBM_File|if|O|ok|open|Pod::Simple::Debug|so
+rt|Thread|threads/;$not={map{$_=>1}split/\|/,$not};print"#!/usr/bin/p
+erl\n# Load all core Perl modules, pragmas and extensions\n# Exceptio
+ns, to prevent errors:\n".(join "\n", map {"#$_"} sort {lc$a cmp lc$b
+} keys %$not).")\n\n";@_=grep/\.pm/,(ExtUtils::Installed->files("Perl
+"));for(@_){$m=Module::Metadata->new_from_file($_)->{module} or next;
+push@m,$m}for(sort{lc$a cmp lc$b}@m){print $not->{$_}?"#":"","use $_;
+\n"}print"\nprint `ps -v | grep \"\$\$\"`;\n"' > useallcore; perl use
+allcore
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