I don't know why the hints are undef for c, but I can confirm it's accurate. 

$ diff -u \
   <( perl -MO=Concise,b b.pl 2>&1 ) \
   <( perl -MO=Concise,c b.pl 2>&1 )
--- /dev/fd/63  2023-03-06 20:59:39.932888013 -0400
+++ /dev/fd/62  2023-03-06 20:59:39.932888013 -0400
@@ -1,8 +1,8 @@
 b.pl syntax OK
-main::b:
+main::c:
 5  <1> leavesub[1 ref] K/REFC,1 ->(end)
 -     <@> lineseq KP ->5
-1        <;> nextstate(main 1252 b.pl:15) v:%,*,&,x*,x&,x$,fea=15 ->2
+1        <;> nextstate(main 1257 b.pl:16) v:*,&,x*,x&,x$,fea=1 ->2
 4        <1> entersub KS ->5
 -           <1> ex-list K ->4
 2              <0> pushmark s ->3

[download]

Note the different value of the hints (fea= for "feature") for the two lines.

In reply to Re^3: A plague on all your features by ikegami
in thread A plague on all your features by Anonymous Monk

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