usenamedanoncv: named __ANON__ => name@

See [cperl #370]: We should no throw away information for no good reason.
Mark anonymised functions with a @ suffix, keeping their old name.
Esp. with upcoming more and more cvref's without GV.
Only if a sub has no name, like my $anon = sub {}; use __ANON__.

Add GV_ANON flag to create named anonymous XS functions via newXS_len_flags().

$ cperl -Dt -d:NYTProf -e0
...
(-e:0)	nextstate
(-e:0)	pushmark
(-e:0)	const(PV("Devel::NYTProf"))
(-e:0)	method_named(->import)
(-e:0)	entersub(import@)   # was entersub(__ANON_)
(-e:0)	enterxssub(import@) # was enterxssub(__ANON_)
(-e:0)	leavesub

The import XS method has no name (but an attached CV), so a dummy anon
CvGV is created.
Devel::NYTProf even creates numbered variants, like BEGIN@4.
This might be too expensive here.

We could then use the @ CvNAME suffix for marking multi methods
(new@int, new@int,str) (i.e. same name, but different methods),
as well as marking multiple variants of special blocks (BEGIN@1)
for easier identification.

Author: rurban

Configure

@@ -1409,6 +1409,7 @@ yaccflags=''
 CONFIG=''
 usecperl=''
 fake_signatures=''
+usenamedanoncv=''
 
 : Detect odd OSs
 define='define'
@@ -23790,6 +23791,32 @@ case "$ans" in
         exit 1 ;;
 esac
 
+case "$usenamedanoncv" in
+$define|true|[yY]*)	dflt='y' ;;
+undef|[nN]*)		dflt='n' ;;
+*) case "$usecperl" in
+       define) 		dflt='y' ;;
+       *)	    	dflt='n' ;;
+   esac
+   ;;
+esac
+cat <<EOM
+
+Would you like to build Perl with named anonymous CVs instead of using
+the old __ANON__ name? With usenamedanoncv every anonymous CV gets the
+old name plus a @ appended, to mark this name as orphaned or anon.
+
+If this doesn't make any sense to you, just accept the default '$dflt'.
+EOM
+rp='Use usenamedanoncv?'
+. ./myread
+case "$ans" in
+y|Y)	val="$define" ;;
+*)	val="$undef"  ;;
+esac
+set usenamedanoncv
+eval $setvar
+
 : Check extensions
 echo " "
 echo "Looking for extensions..." >&4
@@ -25478,6 +25505,7 @@ usemallocwrap='$usemallocwrap'
 usemorebits='$usemorebits'
 usemultiplicity='$usemultiplicity'
 usemymalloc='$usemymalloc'
+usenamedanoncv='$usenamedanoncv'
 usenm='$usenm'
 usensgetexecutablepath='$usensgetexecutablepath'
 useopcode='$useopcode'

Cross/config.sh-arm-linux

@@ -1146,6 +1146,7 @@ usemallocwrap='define'
 usemorebits='undef'
 usemultiplicity='undef'
 usemymalloc='n'
+usenamedanoncv='define'
 usenm='false'
 usensgetexecutablepath='undef'
 useopcode='true'

NetWare/config.wc

@@ -1109,6 +1109,7 @@ usemallocwrap='undef'
 usemorebits='undef'
 usemultiplicity='define'
 usemymalloc='n'
+usenamedanoncv='define'
 usenm='false'
 usensgetexecutablepath='undef'
 useopcode='true'

Porting/config.sh

@@ -1193,6 +1193,7 @@ usemallocwrap='define'
 usemorebits='undef'
 usemultiplicity='undef'
 usemymalloc='n'
+usenamedanoncv='define'
 usenm='false'
 usensgetexecutablepath='undef'
 useopcode='true'

config_h.SH

@@ -5432,6 +5432,15 @@ sed <<!GROK!THIS! >$CONFIG_H -e 's!^#undef\(.*/\)\*!/\*#define\1 \*!' -e 's!^#un
 #$fake_signatures	PERL_FAKE_SIGNATURE		/**/
 #endif
 
+/* USE_NAMED_ANONCV:
+ *	This symbol, if defined, indicates that Perl is compiled with usenamedanoncv,
+ *      using name@ instead of __ANON__.
+ *      It is the default since cperl-5.28.0.
+ */
+#ifndef USE_NAMED_ANONCV
+#$usenamedanoncv	USE_NAMED_ANONCV		/**/
+#endif
+
 /* USE_SANITIZE_ADDRESS:
  *	This symbol, if defined, indicates that Perl is compiled with -fsanitize=address
  */

configure.com

@@ -2744,6 +2744,28 @@ $   if ans.eqs."TWO_POT" then use_two_pot_malloc = "Y"
 $   if ans.eqs."PACK_MALLOC" then use_pack_malloc = "Y"
 $ ENDIF
 $!
+$!
+$ echo ""
+$ echo "Would you like to build Perl with named anonymous CVs instead of using"
+$ echo "the old __ANON__ name? With usenamedanoncv every anonymous CV gets the"
+$ echo "old name plus a @ appended, to mark this name as orphaned or anon."
+$ echo ""
+$ bool_dflt = "y"
+$ IF F$TYPE(usenamedanoncv) .nes. ""
+$ then
+$   if usenamedanoncv .and. usenamedanoncv .eqs. "undef" then bool_dflt = "n"
+$ endif
+$ rp = "Use named anoncv? [''bool_dflt'] "
+$ GOSUB myread
+$ usenamedanoncv = ans
+$ IF usenamedanoncv
+$ THEN
+$   usenamedanoncv = "define"
+$ ELSE
+$   usenamedanoncv = "undef"
+$ ENDIF
+$ !
+$ !
 $ xs_extensions = ""
 $ xxx = ""
 $ OPEN/READ CONFIG 'manifestfound'
@@ -6822,6 +6844,7 @@ $ WC "uselongdouble='" + uselongdouble + "'"
 $ WC "usemorebits='" + usemorebits + "'"
 $ WC "usemultiplicity='" + usemultiplicity + "'"
 $ WC "usemymalloc='" + usemymalloc + "'"
+$ WC "usenamedanoncv='" + usenamedanoncv + "'"
 $ WC "useperlio='define'"
 $ WC "useposix='false'"
 $ WC "usequadmath='undef'"

ext/Config/Config_xs.in

@@ -1495,6 +1495,7 @@ usemallocwrap,		T_INV,0,ALN64I"@@usemallocwrap@@"
 usemorebits,		T_INV,0,ALN64I"@@usemorebits@@"
 usemultiplicity,	T_INV,0,ALN64I"@@usemultiplicity@@"
 usemymalloc,		T_INV,0,ALN64I"@@usemymalloc@@"
+usenamedanoncv,		T_INV,0,ALN64I"@@usenamedanoncv@@"
 usenm,			T_INV,0,ALN64I"@@usenm@@"
 usensgetexecutablepath,	T_INV,0,ALN64I"@@usensgetexecutablepath@@"
 useopcode,		T_INV,0,ALN64I"@@useopcode@@"