Const Boy II: The Localizing

Message-ID: <20050622144059.GA19598@petdance.com>

p4raw-id: //depot/perl@24945

14 files changed, 405 insertions, 396 deletions

diff --git a/autodoc.pl b/autodoc.pl
index 4c5c60ff0d..d347e4c95e 100644
--- a/autodoc.pl
+++ b/autodoc.pl
@@ -53,7 +53,7 @@ sub walk_table (&@) {
 	else {
 	    @args = split /\s*\|\s*/, $_;
 	}
-	s/\bNN\b\s+// for @args;
+	s/\b(NN|NULLOK)\b\s+//g for @args;
 	print $F $function->(@args);
     }
     print $F $trailer if $trailer;
diff --git a/embed.fnc b/embed.fnc
index 1bf8f08952..c05c4220ac 100644
--- a/embed.fnc
+++ b/embed.fnc
@@ -31,6 +31,11 @@
 :
 : Pointer parameters that must not be passed NULLs should be prefixed with NN.
 :
+: Pointer parameters that may be NULL should be prefixed with NULLOK.  This has
+: no effect on output yet.  It's a notation for the maintainers to know "I have
+: defined whether NULL is OK or not" rather than having neither NULL or NULLOK,
+: which is ambiguous.
+:
 : Individual flags may be separated by whitespace.
 :
 : New global functions should be added at the end for binary compatibility
@@ -90,7 +95,7 @@ p	|OP*	|append_list	|I32 optype|LISTOP* first|LISTOP* last
 p	|I32	|apply		|I32 type|SV** mark|SV** sp
 ApM	|void	|apply_attrs_string|const char *stashpv|CV *cv|const char *attrstr|STRLEN len
 Apd	|void	|av_clear	|AV* ar
-ApdR	|SV*	|av_delete	|AV* ar|I32 key|I32 flags
+Apd	|SV*	|av_delete	|AV* ar|I32 key|I32 flags
 ApdR	|bool	|av_exists	|AV* ar|I32 key
 Apd	|void	|av_extend	|NN AV* ar|I32 key
 pR	|AV*	|av_fake	|I32 size|NN SV** svp
@@ -98,7 +103,7 @@ ApdR	|SV**	|av_fetch	|AV* ar|I32 key|I32 lval
 Apd	|void	|av_fill	|AV* ar|I32 fill
 ApdR	|I32	|av_len		|const AV* ar
 ApdR	|AV*	|av_make	|I32 size|NN SV** svp
-ApdR	|SV*	|av_pop		|AV* ar
+Apd	|SV*	|av_pop		|AV* ar
 Apd	|void	|av_push	|AV* ar|SV* val
 p	|void	|av_reify	|AV* ar
 ApdR	|SV*	|av_shift	|AV* ar
@@ -265,8 +270,7 @@ Ap	|GV*	|gv_fetchpv	|const char* name|I32 add|I32 sv_type
 Ap	|void	|gv_fullname	|SV* sv|const GV* gv
 Apmb	|void	|gv_fullname3	|SV* sv|const GV* gv|const char* prefix
 Ap	|void	|gv_fullname4	|SV* sv|const GV* gv|const char* prefix|bool keepmain
-Ap	|void	|gv_init	|NN GV* gv|NN HV* stash|NN const char* name \
-				|STRLEN len|int multi
+Ap	|void	|gv_init	|NN GV* gv|HV* stash|NN const char* name|STRLEN len|int multi
 Apd	|HV*	|gv_stashpv	|const char* name|I32 create
 Apd	|HV*	|gv_stashpvn	|const char* name|U32 namelen|I32 create
 Apd	|HV*	|gv_stashsv	|SV* sv|I32 create
@@ -539,8 +543,8 @@ Apda	|SV*	|newSVhek	|const HEK *hek
 Apda	|SV*	|newSVpvn_share	|const char* s|I32 len|U32 hash
 Afpda	|SV*	|newSVpvf	|const char* pat|...
 Ap	|SV*	|vnewSVpvf	|const char* pat|va_list* args
-Apda	|SV*	|newSVrv	|SV* rv|const char* classname
-Apda	|SV*	|newSVsv	|SV* old
+Apda	|SV*	|newSVrv	|NN SV* rv|NULLOK const char* classname
+Apda	|SV*	|newSVsv	|NULLOK SV* old
 Apa	|OP*	|newUNOP	|I32 type|I32 flags|OP* first
 Apa	|OP*	|newWHILEOP	|I32 flags|I32 debuggable|LOOP* loop \
 				|I32 whileline|OP* expr|OP* block|OP* cont \
@@ -767,9 +771,9 @@ Apd	|void	|sv_magic	|NN SV* sv|SV* obj|int how|const char* name \
 				|I32 namlen
 Apd	|MAGIC *|sv_magicext	|NN SV* sv|SV* obj|int how|const MGVTBL *vtbl \
 				|const char* name|I32 namlen
-Apd	|SV*	|sv_mortalcopy	|NN SV* oldsv
+ApdaR	|SV*	|sv_mortalcopy	|NULLOK SV* oldsv
 ApdR	|SV*	|sv_newmortal
-Apd	|SV*	|sv_newref	|SV* sv
+Apd	|SV*	|sv_newref	|NULLOK SV* sv
 Ap	|char*	|sv_peek	|SV* sv
 Apd	|void	|sv_pos_u2b	|SV* sv|NN I32* offsetp|I32* lenp
 Apd	|void	|sv_pos_b2u	|SV* sv|NN I32* offsetp
@@ -792,9 +796,8 @@ Apd	|void	|sv_setnv	|SV* sv|NV num
 Apd	|SV*	|sv_setref_iv	|SV* rv|const char* classname|IV iv
 Apd	|SV*	|sv_setref_uv	|SV* rv|const char* classname|UV uv
 Apd	|SV*	|sv_setref_nv	|SV* rv|const char* classname|NV nv
-Apd	|SV*	|sv_setref_pv	|SV* rv|const char* classname|void* pv
-Apd	|SV*	|sv_setref_pvn	|SV* rv|const char* classname|char* pv \
-				|STRLEN n
+Apd	|SV*	|sv_setref_pv	|SV* rv|const char* classname|NULLOK void* pv
+Apd	|SV*	|sv_setref_pvn	|SV* rv|const char* classname|NN const char* pv|STRLEN n
 Apd	|void	|sv_setpv	|SV* sv|const char* ptr
 Apd	|void	|sv_setpvn	|NN SV* sv|const char* ptr|STRLEN len
 Amdb	|void	|sv_setsv	|SV* dsv|SV* ssv
@@ -901,19 +904,19 @@ Apd	|void	|sv_usepvn_mg	|SV *sv|char *ptr|STRLEN len
 Ap	|MGVTBL*|get_vtbl	|int vtbl_id
 Ap	|char*	|pv_display	|SV *dsv|const char *pv|STRLEN cur|STRLEN len \
 				|STRLEN pvlim
-Afp	|void	|dump_indent	|I32 level|PerlIO *file|const char* pat|...
-Ap	|void	|dump_vindent	|I32 level|PerlIO *file|const char* pat \
+Afp	|void	|dump_indent	|I32 level|NN PerlIO *file|const char* pat|...
+Ap	|void	|dump_vindent	|I32 level|NN PerlIO *file|const char* pat \
 				|va_list *args
-Ap	|void	|do_gv_dump	|I32 level|PerlIO *file|const char *name|GV *sv
-Ap	|void	|do_gvgv_dump	|I32 level|PerlIO *file|const char *name|GV *sv
-Ap	|void	|do_hv_dump	|I32 level|PerlIO *file|const char *name|HV *sv
-Ap	|void	|do_magic_dump	|I32 level|PerlIO *file|const MAGIC *mg|I32 nest \
+Ap	|void	|do_gv_dump	|I32 level|NN PerlIO *file|const char *name|GV *sv
+Ap	|void	|do_gvgv_dump	|I32 level|NN PerlIO *file|const char *name|GV *sv
+Ap	|void	|do_hv_dump	|I32 level|NN PerlIO *file|const char *name|HV *sv
+Ap	|void	|do_magic_dump	|I32 level|NN PerlIO *file|const MAGIC *mg|I32 nest \
 				|I32 maxnest|bool dumpops|STRLEN pvlim
-Ap	|void	|do_op_dump	|I32 level|PerlIO *file|const OP *o
-Ap	|void	|do_pmop_dump	|I32 level|PerlIO *file|const PMOP *pm
-Ap	|void	|do_sv_dump	|I32 level|PerlIO *file|SV *sv|I32 nest \
+Ap	|void	|do_op_dump	|I32 level|NN PerlIO *file|const OP *o
+Ap	|void	|do_pmop_dump	|I32 level|NN PerlIO *file|const PMOP *pm
+Ap	|void	|do_sv_dump	|I32 level|NN PerlIO *file|NULLOK SV *sv|I32 nest \
 				|I32 maxnest|bool dumpops|STRLEN pvlim
-Ap	|void	|magic_dump	|const MAGIC *mg
+Ap	|void	|magic_dump	|NULLOK const MAGIC *mg
 Ap	|void	|reginitcolors
 Apd	|char*	|sv_2pv_nolen	|SV* sv
 Apd	|char*	|sv_2pvutf8_nolen|SV* sv
@@ -999,8 +1002,8 @@ sa	|HE*	|new_he
 s	|void	|del_he		|NN HE *p
 sa	|HEK*	|save_hek_flags	|NN const char *str|I32 len|U32 hash|int flags
 s	|void	|hv_magic_check	|NN HV *hv|NN bool *needs_copy|NN bool *needs_store
-s	|void	|unshare_hek_or_pvn|const HEK* hek|const char* str|I32 len|U32 hash
-sR	|HEK*	|share_hek_flags|const char* sv|I32 len|U32 hash|int flags
+s	|void	|unshare_hek_or_pvn|NULLOK const HEK* hek|NULLOK const char* str|I32 len|U32 hash
+sR	|HEK*	|share_hek_flags|NN const char* sv|I32 len|U32 hash|int flags
 rs	|void	|hv_notallowed	|int flags|NN const char *key|I32 klen|NN const char *msg
 s	|struct xpvhv_aux*|hv_auxinit|NN HV *hv
 sM	|SV*	|hv_delete_common|HV* tb|SV* key_sv|const char* key|STRLEN klen|int k_flags|I32 d_flags|U32 hash
@@ -1224,15 +1227,15 @@ s	|SV*	|save_scalar_at	|SV **sptr
 #endif
 
 #if defined(PERL_IN_SV_C) || defined(PERL_DECL_PROT)
-s	|IV	|asIV		|SV* sv
-s	|UV	|asUV		|SV* sv
-s	|void	|sv_unglob	|SV* sv
-s	|void	|not_a_number	|SV *sv
-s	|I32	|visit		|SVFUNC_t f|U32 flags|U32 mask
-s	|void	|sv_add_backref	|SV *tsv|SV *sv
-s	|void	|sv_del_backref	|SV *sv
-s	|SV *	|varname	|GV *gv|NN const char *gvtype|PADOFFSET targ \
-				|SV *keyname|I32 aindex|int subscript_type
+sR	|IV	|asIV		|NN SV* sv
+sR	|UV	|asUV		|NN SV* sv
+s	|void	|sv_unglob	|NN SV* sv
+s	|void	|not_a_number	|NN SV *sv
+s	|I32	|visit		|NN SVFUNC_t f|U32 flags|U32 mask
+s	|void	|sv_add_backref	|NN SV *tsv|NN SV *sv
+s	|void	|sv_del_backref	|NN SV *sv
+sR	|SV *	|varname	|NULLOK GV *gv|NN const char *gvtype|PADOFFSET targ \
+				|NULLOK SV *keyname|I32 aindex|int subscript_type
 #  ifdef DEBUGGING
 s	|void	|del_sv	|SV *p
 #  endif
@@ -1334,7 +1337,7 @@ s	|STRLEN	|is_utf8_char_slow|NN const U8 *s|const STRLEN len
 
 START_EXTERN_C
 
-Apd	|void	|sv_setsv_flags	|NN SV* dsv|SV* ssv|I32 flags
+Apd	|void	|sv_setsv_flags	|NN SV* dsv|NULLOK SV* ssv|I32 flags
 Apd	|void	|sv_catpvn_flags|NN SV* sv|NN const char* ptr|STRLEN len|I32 flags
 Apd	|void	|sv_catsv_flags	|NN SV* dsv|SV* ssv|I32 flags
 Apd	|STRLEN	|sv_utf8_upgrade_flags|NN SV *sv|I32 flags
diff --git a/embed.pl b/embed.pl
index 27815ae9cd..778090f8a0 100755
--- a/embed.pl
+++ b/embed.pl
@@ -195,6 +195,7 @@ sub write_protos {
 	    for my $arg ( @args ) {
 		++$n;
 		push( @nonnull, $n ) if ( $arg =~ s/\s*\bNN\b\s+// );
+		$arg =~ s/\s*\bNULLOK\b\s+//; # strip NULLOK with no effect
 	    }
 	    $ret .= join ", ", @args;
 	}
@@ -953,3 +954,5 @@ my %vfuncs = qw(
     Perl_dump_indent		Perl_dump_vindent
     Perl_default_protect	Perl_vdefault_protect
 );
+
+# ex: set ts=8 sts=4 sw=4 noet:
diff --git a/hv.c b/hv.c
index eb2a1a5aa7..b3c6b2f33d 100644
--- a/hv.c
+++ b/hv.c
@@ -171,7 +171,7 @@ Perl_he_dup(pTHX_ HE *e, bool shared, CLONE_PARAMS* param)
     else if (shared) {
 	/* This is hek_dup inlined, which seems to be important for speed
 	   reasons.  */
-	HEK *source = HeKEY_hek(e);
+	HEK * const source = HeKEY_hek(e);
 	HEK *shared = (HEK*)ptr_table_fetch(PL_ptr_table, source);
 
 	if (shared) {
@@ -198,7 +198,7 @@ static void
 S_hv_notallowed(pTHX_ int flags, const char *key, I32 klen,
 		const char *msg)
 {
-    SV *sv = sv_newmortal();
+    SV * const sv = sv_newmortal();
     if (!(flags & HVhek_FREEKEY)) {
 	sv_setpvn(sv, key, klen);
     }
@@ -2309,7 +2309,6 @@ Perl_share_hek(pTHX_ const char *str, I32 len, register U32 hash)
 STATIC HEK *
 S_share_hek_flags(pTHX_ const char *str, I32 len, register U32 hash, int flags)
 {
-    register XPVHV* xhv;
     register HE *entry;
     register HE **oentry;
     I32 found = 0;
@@ -2323,7 +2322,7 @@ S_share_hek_flags(pTHX_ const char *str, I32 len, register U32 hash, int flags)
 	Can't rehash the shared string table, so not sure if it's worth
 	counting the number of entries in the linked list
     */
-    xhv = (XPVHV*)SvANY(PL_strtab);
+    register XPVHV * const xhv = (XPVHV*)SvANY(PL_strtab);
     /* assert(xhv_array != 0) */
     LOCK_STRTAB_MUTEX;
     oentry = &(HvARRAY(PL_strtab))[hash & (I32) HvMAX(PL_strtab)];
diff --git a/perl.c b/perl.c
index 1d6bc6a0d2..f8fd6d3e1e 100644
--- a/perl.c
+++ b/perl.c
@@ -428,6 +428,7 @@ perl_destruct(pTHXx)
         int x = 0;
 
         JMPENV_PUSH(x);
+	PERL_UNUSED_VAR(x);
         if (PL_endav && !PL_minus_c)
             call_list(PL_scopestack_ix, PL_endav);
         JMPENV_POP;
@@ -1231,15 +1232,10 @@ setuid perl scripts securely.\n");
     if (!PL_rehash_seed_set)
 	 PL_rehash_seed = get_hash_seed();
     {
-	 char *s = PerlEnv_getenv("PERL_HASH_SEED_DEBUG");
+	const char *s = PerlEnv_getenv("PERL_HASH_SEED_DEBUG");
 
-	 if (s) {
-	      int i = atoi(s);
-
-	      if (i == 1)
-		   PerlIO_printf(Perl_debug_log, "HASH_SEED = %"UVuf"\n",
-				 PL_rehash_seed);
-	 }
+	if (s && (atoi(s) == 1))
+	    PerlIO_printf(Perl_debug_log, "HASH_SEED = %"UVuf"\n", PL_rehash_seed);
     }
 #endif /* #if defined(USE_HASH_SEED) || defined(USE_HASH_SEED_EXPLICIT) */
 
@@ -1256,10 +1252,10 @@ setuid perl scripts securely.\n");
 	 * --jhi */
 	 const char *s = NULL;
 	 int i;
-	 UV mask =
+	 const UV mask =
 	   ~(UV)(PTRSIZE == 4 ? 3 : PTRSIZE == 8 ? 7 : PTRSIZE == 16 ? 15 : 0);
          /* Do the mask check only if the args seem like aligned. */
-	 UV aligned =
+	 const UV aligned =
 	   (mask < ~(UV)0) && ((PTR2UV(argv[0]) & mask) == PTR2UV(argv[0]));
 
 	 /* See if all the arguments are contiguous in memory.  Note
diff --git a/perlio.c b/perlio.c
index df4ddc0e8a..a3d2d6fad2 100644
--- a/perlio.c
+++ b/perlio.c
@@ -650,6 +650,9 @@ PerlIO_clone(pTHX_ PerlInterpreter *proto, CLONE_PARAMS *param)
 		f++;
 	    }
 	}
+#else
+    PERL_UNUSED_ARG(proto);
+    PERL_UNUSED_ARG(param);
 #endif
 }
 
@@ -2178,6 +2181,7 @@ PerlIO_sv_dup(pTHX_ SV *arg, CLONE_PARAMS *param)
 	return newSVsv(arg);
     }
 #else
+    PERL_UNUSED_ARG(param);
     return newSVsv(arg);
 #endif
 }
@@ -2185,7 +2189,7 @@ PerlIO_sv_dup(pTHX_ SV *arg, CLONE_PARAMS *param)
 PerlIO *
 PerlIOBase_dup(pTHX_ PerlIO *f, PerlIO *o, CLONE_PARAMS *param, int flags)
 {
-    PerlIO *nexto = PerlIONext(o);
+    PerlIO * const nexto = PerlIONext(o);
     if (PerlIOValid(nexto)) {
 	const PerlIO_funcs * const tab = PerlIOBase(nexto)->tab;
 	if (tab && tab->Dup)
@@ -2545,6 +2549,7 @@ PerlIOUnix_write(pTHX_ PerlIO *f, const void *vbuf, Size_t count)
 	}
 	PERL_ASYNC_CHECK();
     }
+    /*NOTREACHED*/
 }
 
 Off_t
diff --git a/pod/perlapi.pod b/pod/perlapi.pod
index c27e4e2dc3..6b603bf774 100644
--- a/pod/perlapi.pod
+++ b/pod/perlapi.pod
@@ -4873,7 +4873,7 @@ of 1, and the RV will be returned.
 
 Note that C<sv_setref_pv> copies the pointer while this copies the string.
 
-	SV*	sv_setref_pvn(SV* rv, const char* classname, char* pv, STRLEN n)
+	SV*	sv_setref_pvn(SV* rv, const char* classname, const char* pv, STRLEN n)
 
 =for hackers
 Found in file sv.c
diff --git a/pp.c b/pp.c
index 11ca9ced47..e2649d30ca 100644
--- a/pp.c
+++ b/pp.c
@@ -83,7 +83,7 @@ PP(pp_padav)
 	if (SvMAGICAL(TARG)) {
 	    U32 i;
 	    for (i=0; i < (U32)maxarg; i++) {
-		SV **svp = av_fetch((AV*)TARG, i, FALSE);
+		SV ** const svp = av_fetch((AV*)TARG, i, FALSE);
 		SP[i+1] = (svp) ? *svp : &PL_sv_undef;
 	    }
 	}
@@ -93,7 +93,7 @@ PP(pp_padav)
 	SP += maxarg;
     }
     else if (gimme == G_SCALAR) {
-	SV* sv = sv_newmortal();
+	SV* const sv = sv_newmortal();
 	const I32 maxarg = AvFILL((AV*)TARG) + 1;
 	sv_setiv(sv, maxarg);
 	PUSHs(sv);
@@ -121,7 +121,7 @@ PP(pp_padhv)
 	RETURNOP(do_kv());
     }
     else if (gimme == G_SCALAR) {
-	SV* sv = Perl_hv_scalar(aTHX_ (HV*)TARG);
+	SV* const sv = Perl_hv_scalar(aTHX_ (HV*)TARG);
 	SETs(sv);
     }
     RETURN;
@@ -144,7 +144,7 @@ PP(pp_rv2gv)
 
 	sv = SvRV(sv);
 	if (SvTYPE(sv) == SVt_PVIO) {
-	    GV *gv = (GV*) sv_newmortal();
+	    GV * const gv = (GV*) sv_newmortal();
 	    gv_init(gv, 0, "", 0, 0);
 	    GvIOp(gv) = (IO *)sv;
 	    (void)SvREFCNT_inc(sv);
@@ -201,7 +201,7 @@ PP(pp_rv2gv)
 	    if ((PL_op->op_flags & OPf_SPECIAL) &&
 		!(PL_op->op_flags & OPf_MOD))
 	    {
-		SV * temp = (SV*)gv_fetchsv(sv, FALSE, SVt_PVGV);
+		SV * const temp = (SV*)gv_fetchsv(sv, FALSE, SVt_PVGV);
 		if (!temp
 		    && (!is_gv_magical_sv(sv,0)
 			|| !(sv = (SV*)gv_fetchsv(sv, TRUE, SVt_PVGV)))) {
@@ -294,8 +294,8 @@ PP(pp_rv2sv)
 PP(pp_av2arylen)
 {
     dSP;
-    AV *av = (AV*)TOPs;
-    SV **sv = Perl_av_arylen_p(aTHX_ (AV*)av);
+    AV * const av = (AV*)TOPs;
+    SV ** const sv = Perl_av_arylen_p(aTHX_ (AV*)av);
     if (!*sv) {
 	*sv = NEWSV(0,0);
 	sv_upgrade(*sv, SVt_PVMG);
@@ -325,10 +325,8 @@ PP(pp_pos)
 	RETURN;
     }
     else {
-	MAGIC* mg;
-
 	if (SvTYPE(sv) >= SVt_PVMG && SvMAGIC(sv)) {
-	    mg = mg_find(sv, PERL_MAGIC_regex_global);
+	    const MAGIC * const mg = mg_find(sv, PERL_MAGIC_regex_global);
 	    if (mg && mg->mg_len >= 0) {
 		I32 i = mg->mg_len;
 		if (DO_UTF8(sv))
@@ -504,10 +502,8 @@ S_refto(pTHX_ SV *sv)
 PP(pp_ref)
 {
     dSP; dTARGET;
-    SV *sv;
     const char *pv;
-
-    sv = POPs;
+    SV * const sv = POPs;
 
     if (sv && SvGMAGICAL(sv))
 	mg_get(sv);
@@ -515,8 +511,7 @@ PP(pp_ref)
     if (!sv || !SvROK(sv))
 	RETPUSHNO;
 
-    sv = SvRV(sv);
-    pv = sv_reftype(sv,TRUE);
+    pv = sv_reftype(SvRV(sv),TRUE);
     PUSHp(pv, strlen(pv));
     RETURN;
 }
@@ -529,7 +524,7 @@ PP(pp_bless)
     if (MAXARG == 1)
 	stash = CopSTASH(PL_curcop);
     else {
-	SV *ssv = POPs;
+	SV * const ssv = POPs;
 	STRLEN len;
 	const char *ptr;
 
@@ -548,63 +543,60 @@ PP(pp_bless)
 
 PP(pp_gelem)
 {
-    GV *gv;
-    SV *sv;
-    SV *tmpRef;
-    const char *elem;
     dSP;
 
-    sv = POPs;
-    elem = SvPV_nolen_const(sv);
-    gv = (GV*)POPs;
-    tmpRef = Nullsv;
+    SV *sv = POPs;
+    const char * const elem = SvPV_nolen_const(sv);
+    GV * const gv = (GV*)POPs;
+    SV * tmpRef = Nullsv;
+
     sv = Nullsv;
     if (elem) {
 	/* elem will always be NUL terminated.  */
-	const char *elem2 = elem + 1;
+	const char * const second_letter = elem + 1;
 	switch (*elem) {
 	case 'A':
-	    if (strEQ(elem2, "RRAY"))
+	    if (strEQ(second_letter, "RRAY"))
 		tmpRef = (SV*)GvAV(gv);
 	    break;
 	case 'C':
-	    if (strEQ(elem2, "ODE"))
+	    if (strEQ(second_letter, "ODE"))
 		tmpRef = (SV*)GvCVu(gv);
 	    break;
 	case 'F':
-	    if (strEQ(elem2, "ILEHANDLE")) {
+	    if (strEQ(second_letter, "ILEHANDLE")) {
 		/* finally deprecated in 5.8.0 */
 		deprecate("*glob{FILEHANDLE}");
 		tmpRef = (SV*)GvIOp(gv);
 	    }
 	    else
-		if (strEQ(elem2, "ORMAT"))
+		if (strEQ(second_letter, "ORMAT"))
 		    tmpRef = (SV*)GvFORM(gv);
 	    break;
 	case 'G':
-	    if (strEQ(elem2, "LOB"))
+	    if (strEQ(second_letter, "LOB"))
 		tmpRef = (SV*)gv;
 	    break;
 	case 'H':
-	    if (strEQ(elem2, "ASH"))
+	    if (strEQ(second_letter, "ASH"))
 		tmpRef = (SV*)GvHV(gv);
 	    break;
 	case 'I':
-	    if (*elem2 == 'O' && !elem[2])
+	    if (*second_letter == 'O' && !elem[2])
 		tmpRef = (SV*)GvIOp(gv);
 	    break;
 	case 'N':
-	    if (strEQ(elem2, "AME"))
+	    if (strEQ(second_letter, "AME"))
 		sv = newSVpvn(GvNAME(gv), GvNAMELEN(gv));
 	    break;
 	case 'P':
-	    if (strEQ(elem2, "ACKAGE")) {
+	    if (strEQ(second_letter, "ACKAGE")) {
 		const HEK *hek = HvNAME_HEK(GvSTASH(gv));
 		sv = hek ? newSVhek(hek) : newSVpvn("__ANON__", 8);
 	    }
 	    break;
 	case 'S':
-	    if (strEQ(elem2, "CALAR"))
+	    if (strEQ(second_letter, "CALAR"))
 		tmpRef = GvSV(gv);
 	    break;
 	}
@@ -670,7 +662,7 @@ PP(pp_study)
     sfirst -= 256;
 
     while (--pos >= 0) {
-	ch = s[pos];
+	register const I32 ch = s[pos];
 	if (sfirst[ch] >= 0)
 	    snext[pos] = sfirst[ch] - pos;
 	else
@@ -743,9 +735,8 @@ PP(pp_chomp)
 PP(pp_defined)
 {
     dSP;
-    register SV* sv;
+    register SV* const sv = POPs;
 
-    sv = POPs;
     if (!sv || !SvANY(sv))
 	RETPUSHNO;
     switch (SvTYPE(sv)) {
@@ -917,7 +908,7 @@ PP(pp_pow)
             if (baseuok) {
                 baseuv = SvUVX(TOPm1s);
             } else {
-                IV iv = SvIVX(TOPm1s);
+		const IV iv = SvIVX(TOPm1s);
                 if (iv >= 0) {
                     baseuv = iv;
                     baseuok = TRUE; /* effectively it's a UV now */
@@ -959,7 +950,7 @@ PP(pp_pow)
                     for (; power; base *= base, n++) {
                         /* Do I look like I trust gcc with long longs here?
                            Do I hell.  */
-                        UV bit = (UV)1 << (UV)n;
+			const UV bit = (UV)1 << (UV)n;
                         if (power & bit) {
                             result *= base;
                             /* Only bother to clear the bit if it is set.  */
@@ -991,7 +982,7 @@ PP(pp_pow)
 			register UV base = baseuv;
 			register int n = 0;
 			for (; power; base *= base, n++) {
-			    register UV bit = (UV)1 << (UV)n;
+			    register const UV bit = (UV)1 << (UV)n;
 			    if (power & bit) {
 				result *= base;
 				power -= bit;
@@ -1054,7 +1045,7 @@ PP(pp_multiply)
 	    if (auvok) {
 		alow = SvUVX(TOPm1s);
 	    } else {
-		IV aiv = SvIVX(TOPm1s);
+		const IV aiv = SvIVX(TOPm1s);
 		if (aiv >= 0) {
 		    alow = aiv;
 		    auvok = TRUE; /* effectively it's a UV now */
@@ -1065,7 +1056,7 @@ PP(pp_multiply)
 	    if (buvok) {
 		blow = SvUVX(TOPs);
 	    } else {
-		IV biv = SvIVX(TOPs);
+		const IV biv = SvIVX(TOPs);
 		if (biv >= 0) {
 		    blow = biv;
 		    buvok = TRUE; /* effectively it's a UV now */
@@ -1186,7 +1177,7 @@ PP(pp_divide)
                 right = SvUVX(TOPs);
             }
 	    else {
-                IV biv = SvIVX(TOPs);
+		const IV biv = SvIVX(TOPs);
                 if (biv >= 0) {
                     right = biv;
                     right_non_neg = TRUE; /* effectively it's a UV now */
@@ -1207,7 +1198,7 @@ PP(pp_divide)
                 left = SvUVX(TOPm1s);
             }
 	    else {
-                IV aiv = SvIVX(TOPm1s);
+		const IV aiv = SvIVX(TOPm1s);
                 if (aiv >= 0) {
                     left = aiv;
                     left_non_neg = TRUE; /* effectively it's a UV now */
@@ -1233,7 +1224,7 @@ PP(pp_divide)
 #endif
                 ) {
                 /* Integer division can't overflow, but it can be imprecise.  */
-                UV result = left / right;
+		const UV result = left / right;
                 if (result * right == left) {
                     SP--; /* result is valid */
                     if (left_non_neg == right_non_neg) {
@@ -1282,7 +1273,7 @@ PP(pp_modulo)
             if (!right_neg) {
                 right = SvUVX(POPs);
             } else {
-                IV biv = SvIVX(POPs);
+		const IV biv = SvIVX(POPs);
                 if (biv >= 0) {
                     right = biv;
                     right_neg = FALSE; /* effectively it's a UV now */
@@ -1401,7 +1392,7 @@ PP(pp_repeat)
 	 mg_get(sv);
     if (SvIOKp(sv)) {
 	 if (SvUOK(sv)) {
-	      UV uv = SvUV(sv);
+	      const UV uv = SvUV(sv);
 	      if (uv > IV_MAX)
 		   count = IV_MAX; /* The best we can do? */
 	      else
@@ -1415,7 +1406,7 @@ PP(pp_repeat)
 	 }
     }
     else if (SvNOKp(sv)) {
-	 NV nv = SvNV(sv);
+	 const NV nv = SvNV(sv);
 	 if (nv < 0.0)
 	      count = 0;
 	 else
@@ -1546,7 +1537,7 @@ PP(pp_subtract)
 		if ((auvok = SvUOK(TOPm1s)))
 		    auv = SvUVX(TOPm1s);
 		else {
-		    register IV aiv = SvIVX(TOPm1s);
+		    register const IV aiv = SvIVX(TOPm1s);
 		    if (aiv >= 0) {
 			auv = aiv;
 			auvok = 1;	/* Now acting as a sign flag.  */
@@ -1566,7 +1557,7 @@ PP(pp_subtract)
 	    if (buvok)
 		buv = SvUVX(TOPs);
 	    else {
-		register IV biv = SvIVX(TOPs);
+		register const IV biv = SvIVX(TOPs);
 		if (biv >= 0) {
 		    buv = biv;
 		    buvok = 1;
@@ -1640,7 +1631,7 @@ PP(pp_left_shift)
 {
     dSP; dATARGET; tryAMAGICbin(lshift,opASSIGN);
     {
-      IV shift = POPi;
+      const IV shift = POPi;
       if (PL_op->op_private & HINT_INTEGER) {
 	IV i = TOPi;
 	SETi(i << shift);
@@ -1657,7 +1648,7 @@ PP(pp_right_shift)
 {
     dSP; dATARGET; tryAMAGICbin(rshift,opASSIGN);
     {
-      IV shift = POPi;
+      const IV shift = POPi;
       if (PL_op->op_private & HINT_INTEGER) {
 	IV i = TOPi;
 	SETi(i >> shift);
@@ -1682,16 +1673,16 @@ PP(pp_lt)
 	    bool buvok = SvUOK(TOPs);
 	
 	    if (!auvok && !buvok) { /* ## IV < IV ## */
-		IV aiv = SvIVX(TOPm1s);
-		IV biv = SvIVX(TOPs);
+		const IV aiv = SvIVX(TOPm1s);
+		const IV biv = SvIVX(TOPs);
 		
 		SP--;
 		SETs(boolSV(aiv < biv));
 		RETURN;
 	    }
 	    if (auvok && buvok) { /* ## UV < UV ## */
-		UV auv = SvUVX(TOPm1s);
-		UV buv = SvUVX(TOPs);
+		const UV auv = SvUVX(TOPm1s);
+		const UV buv = SvUVX(TOPs);
 		
 		SP--;
 		SETs(boolSV(auv < buv));
@@ -1699,9 +1690,7 @@ PP(pp_lt)
 	    }
 	    if (auvok) { /* ## UV < IV ## */
 		UV auv;
-		IV biv;
-		
-		biv = SvIVX(TOPs);
+		const IV biv = SvIVX(TOPs);
 		SP--;
 		if (biv < 0) {
 		    /* As (a) is a UV, it's >=0, so it cannot be < */
@@ -1713,10 +1702,9 @@ PP(pp_lt)
 		RETURN;
 	    }
 	    { /* ## IV < UV ## */
-		IV aiv;
+		const IV aiv = SvIVX(TOPm1s);
 		UV buv;
 		
-		aiv = SvIVX(TOPm1s);
 		if (aiv < 0) {
 		    /* As (b) is a UV, it's >=0, so it must be < */
 		    SP--;
@@ -1760,16 +1748,16 @@ PP(pp_gt)
 	    bool buvok = SvUOK(TOPs);
 	
 	    if (!auvok && !buvok) { /* ## IV > IV ## */
-		IV aiv = SvIVX(TOPm1s);
-		IV biv = SvIVX(TOPs);
-		
+		const IV aiv = SvIVX(TOPm1s);
+		const IV biv = SvIVX(TOPs);
+
 		SP--;
 		SETs(boolSV(aiv > biv));
 		RETURN;
 	    }
 	    if (auvok && buvok) { /* ## UV > UV ## */
-		UV auv = SvUVX(TOPm1s);
-		UV buv = SvUVX(TOPs);
+		const UV auv = SvUVX(TOPm1s);
+		const UV buv = SvUVX(TOPs);
 		
 		SP--;
 		SETs(boolSV(auv > buv));
@@ -1777,9 +1765,8 @@ PP(pp_gt)
 	    }
 	    if (auvok) { /* ## UV > IV ## */
 		UV auv;
-		IV biv;
-		
-		biv = SvIVX(TOPs);
+		const IV biv = SvIVX(TOPs);
+
 		SP--;
 		if (biv < 0) {
 		    /* As (a) is a UV, it's >=0, so it must be > */
@@ -1791,10 +1778,9 @@ PP(pp_gt)
 		RETURN;
 	    }
 	    { /* ## IV > UV ## */
-		IV aiv;
+		const IV aiv = SvIVX(TOPm1s);
 		UV buv;
 		
-		aiv = SvIVX(TOPm1s);
 		if (aiv < 0) {
 		    /* As (b) is a UV, it's >=0, so it cannot be > */
 		    SP--;
@@ -1838,8 +1824,8 @@ PP(pp_le)
 	    bool buvok = SvUOK(TOPs);
 	
 	    if (!auvok && !buvok) { /* ## IV <= IV ## */
-		IV aiv = SvIVX(TOPm1s);
-		IV biv = SvIVX(TOPs);
+		const IV aiv = SvIVX(TOPm1s);
+		const IV biv = SvIVX(TOPs);
 		
 		SP--;
 		SETs(boolSV(aiv <= biv));
@@ -1855,9 +1841,8 @@ PP(pp_le)
 	    }
 	    if (auvok) { /* ## UV <= IV ## */
 		UV auv;
-		IV biv;
-		
-		biv = SvIVX(TOPs);
+		const IV biv = SvIVX(TOPs);
+
 		SP--;
 		if (biv < 0) {
 		    /* As (a) is a UV, it's >=0, so a cannot be <= */
@@ -1869,10 +1854,9 @@ PP(pp_le)
 		RETURN;
 	    }
 	    { /* ## IV <= UV ## */
-		IV aiv;
+		const IV aiv = SvIVX(TOPm1s);
 		UV buv;
-		
-		aiv = SvIVX(TOPm1s);
+
 		if (aiv < 0) {
 		    /* As (b) is a UV, it's >=0, so a must be <= */
 		    SP--;
@@ -1916,26 +1900,25 @@ PP(pp_ge)
 	    bool buvok = SvUOK(TOPs);
 	
 	    if (!auvok && !buvok) { /* ## IV >= IV ## */
-		IV aiv = SvIVX(TOPm1s);
-		IV biv = SvIVX(TOPs);
-		
+		const IV aiv = SvIVX(TOPm1s);
+		const IV biv = SvIVX(TOPs);
+
 		SP--;
 		SETs(boolSV(aiv >= biv));
 		RETURN;
 	    }
 	    if (auvok && buvok) { /* ## UV >= UV ## */
-		UV auv = SvUVX(TOPm1s);
-		UV buv = SvUVX(TOPs);
-		
+		const UV auv = SvUVX(TOPm1s);
+		const UV buv = SvUVX(TOPs);
+
 		SP--;
 		SETs(boolSV(auv >= buv));
 		RETURN;
 	    }
 	    if (auvok) { /* ## UV >= IV ## */
 		UV auv;
-		IV biv;
-		
-		biv = SvIVX(TOPs);
+		const IV biv = SvIVX(TOPs);
+
 		SP--;
 		if (biv < 0) {
 		    /* As (a) is a UV, it's >=0, so it must be >= */
@@ -1947,10 +1930,9 @@ PP(pp_ge)
 		RETURN;
 	    }
 	    { /* ## IV >= UV ## */
-		IV aiv;
+		const IV aiv = SvIVX(TOPm1s);
 		UV buv;
-		
-		aiv = SvIVX(TOPm1s);
+
 		if (aiv < 0) {
 		    /* As (b) is a UV, it's >=0, so a cannot be >= */
 		    SP--;
@@ -2007,9 +1989,9 @@ PP(pp_ne)
                    differ from normal zero. As I understand it. (Need to
                    check - is negative zero implementation defined behaviour
                    anyway?). NWC  */
-		UV buv = SvUVX(POPs);
-		UV auv = SvUVX(TOPs);
-		
+		const UV buv = SvUVX(POPs);
+		const UV auv = SvUVX(TOPs);
+
 		SETs(boolSV(auv != buv));
 		RETURN;
 	    }
@@ -2068,12 +2050,12 @@ PP(pp_ncmp)
     if (SvIOK(TOPs)) {
 	SvIV_please(TOPm1s);
 	if (SvIOK(TOPm1s)) {
-	    bool leftuvok = SvUOK(TOPm1s);
-	    bool rightuvok = SvUOK(TOPs);
+	    const bool leftuvok = SvUOK(TOPm1s);
+	    const bool rightuvok = SvUOK(TOPs);
 	    I32 value;
 	    if (!leftuvok && !rightuvok) { /* ## IV <=> IV ## */
-		IV leftiv = SvIVX(TOPm1s);
-		IV rightiv = SvIVX(TOPs);
+		const IV leftiv = SvIVX(TOPm1s);
+		const IV rightiv = SvIVX(TOPs);
 		
 		if (leftiv > rightiv)
 		    value = 1;
@@ -2082,8 +2064,8 @@ PP(pp_ncmp)
 		else
 		    value = 0;
 	    } else if (leftuvok && rightuvok) { /* ## UV <=> UV ## */
-		UV leftuv = SvUVX(TOPm1s);
-		UV rightuv = SvUVX(TOPs);
+		const UV leftuv = SvUVX(TOPm1s);
+		const UV rightuv = SvUVX(TOPs);
 		
 		if (leftuv > rightuv)
 		    value = 1;
@@ -2092,15 +2074,12 @@ PP(pp_ncmp)
 		else
 		    value = 0;
 	    } else if (leftuvok) { /* ## UV <=> IV ## */
-		UV leftuv;
-		IV rightiv;
-		
-		rightiv = SvIVX(TOPs);
+		const IV rightiv = SvIVX(TOPs);
 		if (rightiv < 0) {
 		    /* As (a) is a UV, it's >=0, so it cannot be < */
 		    value = 1;
 		} else {
-		    leftuv = SvUVX(TOPm1s);
+		    const UV leftuv = SvUVX(TOPm1s);
 		    if (leftuv > (UV)rightiv) {
 			value = 1;
 		    } else if (leftuv < (UV)rightiv) {
@@ -2110,15 +2089,12 @@ PP(pp_ncmp)
 		    }
 		}
 	    } else { /* ## IV <=> UV ## */
-		IV leftiv;
-		UV rightuv;
-		
-		leftiv = SvIVX(TOPm1s);
+		const IV leftiv = SvIVX(TOPm1s);
 		if (leftiv < 0) {
 		    /* As (b) is a UV, it's >=0, so it must be < */
 		    value = -1;
 		} else {
-		    rightuv = SvUVX(TOPs);
+		    const UV rightuv = SvUVX(TOPs);
 		    if ((UV)leftiv > rightuv) {
 			value = 1;
 		    } else if ((UV)leftiv < rightuv) {
@@ -2166,7 +2142,7 @@ PP(pp_slt)
     dSP; tryAMAGICbinSET(slt,0);
     {
       dPOPTOPssrl;
-      int cmp = (IN_LOCALE_RUNTIME
+      const int cmp = (IN_LOCALE_RUNTIME
 		 ? sv_cmp_locale(left, right)
 		 : sv_cmp(left, right));
       SETs(boolSV(cmp < 0));
@@ -2179,7 +2155,7 @@ PP(pp_sgt)
     dSP; tryAMAGICbinSET(sgt,0);
     {
       dPOPTOPssrl;
-      int cmp = (IN_LOCALE_RUNTIME
+      const int cmp = (IN_LOCALE_RUNTIME
 		 ? sv_cmp_locale(left, right)
 		 : sv_cmp(left, right));
       SETs(boolSV(cmp > 0));
@@ -2192,7 +2168,7 @@ PP(pp_sle)
     dSP; tryAMAGICbinSET(sle,0);
     {
       dPOPTOPssrl;
-      int cmp = (IN_LOCALE_RUNTIME
+      const int cmp = (IN_LOCALE_RUNTIME
 		 ? sv_cmp_locale(left, right)
 		 : sv_cmp(left, right));
       SETs(boolSV(cmp <= 0));
@@ -2205,7 +2181,7 @@ PP(pp_sge)
     dSP; tryAMAGICbinSET(sge,0);
     {
       dPOPTOPssrl;
-      int cmp = (IN_LOCALE_RUNTIME
+      const int cmp = (IN_LOCALE_RUNTIME
 		 ? sv_cmp_locale(left, right)
 		 : sv_cmp(left, right));
       SETs(boolSV(cmp >= 0));
@@ -2238,7 +2214,7 @@ PP(pp_scmp)
     dSP; dTARGET;  tryAMAGICbin(scmp,0);
     {
       dPOPTOPssrl;
-      int cmp = (IN_LOCALE_RUNTIME
+      const int cmp = (IN_LOCALE_RUNTIME
 		 ? sv_cmp_locale(left, right)
 		 : sv_cmp(left, right));
       SETi( cmp );
@@ -2255,11 +2231,11 @@ PP(pp_bit_and)
       if (SvGMAGICAL(right)) mg_get(right);
       if (SvNIOKp(left) || SvNIOKp(right)) {
 	if (PL_op->op_private & HINT_INTEGER) {
-	  IV i = SvIV_nomg(left) & SvIV_nomg(right);
+	  const IV i = SvIV_nomg(left) & SvIV_nomg(right);
 	  SETi(i);
 	}
 	else {
-	  UV u = SvUV_nomg(left) & SvUV_nomg(right);
+	  const UV u = SvUV_nomg(left) & SvUV_nomg(right);
 	  SETu(u);
 	}
       }
@@ -2280,11 +2256,11 @@ PP(pp_bit_xor)
       if (SvGMAGICAL(right)) mg_get(right);
       if (SvNIOKp(left) || SvNIOKp(right)) {
 	if (PL_op->op_private & HINT_INTEGER) {
-	  IV i = (USE_LEFT(left) ? SvIV_nomg(left) : 0) ^ SvIV_nomg(right);
+	  const IV i = (USE_LEFT(left) ? SvIV_nomg(left) : 0) ^ SvIV_nomg(right);
 	  SETi(i);
 	}
 	else {
-	  UV u = (USE_LEFT(left) ? SvUV_nomg(left) : 0) ^ SvUV_nomg(right);
+	  const UV u = (USE_LEFT(left) ? SvUV_nomg(left) : 0) ^ SvUV_nomg(right);
 	  SETu(u);
 	}
       }
@@ -2305,11 +2281,11 @@ PP(pp_bit_or)
       if (SvGMAGICAL(right)) mg_get(right);
       if (SvNIOKp(left) || SvNIOKp(right)) {
 	if (PL_op->op_private & HINT_INTEGER) {
-	  IV i = (USE_LEFT(left) ? SvIV_nomg(left) : 0) | SvIV_nomg(right);
+	  const IV i = (USE_LEFT(left) ? SvIV_nomg(left) : 0) | SvIV_nomg(right);
 	  SETi(i);
 	}
 	else {
-	  UV u = (USE_LEFT(left) ? SvUV_nomg(left) : 0) | SvUV_nomg(right);
+	  const UV u = (USE_LEFT(left) ? SvUV_nomg(left) : 0) | SvUV_nomg(right);
 	  SETu(u);
 	}
       }
@@ -2326,7 +2302,7 @@ PP(pp_negate)
     dSP; dTARGET; tryAMAGICun(neg);
     {
 	dTOPss;
-	int flags = SvFLAGS(sv);
+	const int flags = SvFLAGS(sv);
 	if (SvGMAGICAL(sv))
 	    mg_get(sv);
 	if ((flags & SVf_IOK) || ((flags & (SVp_IOK | SVp_NOK)) == SVp_IOK)) {
@@ -2408,11 +2384,11 @@ PP(pp_complement)
 	  mg_get(sv);
       if (SvNIOKp(sv)) {
 	if (PL_op->op_private & HINT_INTEGER) {
-	  IV i = ~SvIV_nomg(sv);
+	  const IV i = ~SvIV_nomg(sv);
 	  SETi(i);
 	}
 	else {
-	  UV u = ~SvUV_nomg(sv);
+	  const UV u = ~SvUV_nomg(sv);
 	  SETu(u);
 	}
       }
@@ -2436,7 +2412,7 @@ PP(pp_complement)
 
 	  send = tmps + len;
 	  while (tmps < send) {
-	    UV c = utf8n_to_uvchr(tmps, send-tmps, &l, UTF8_ALLOW_ANYUV);
+	    const UV c = utf8n_to_uvchr(tmps, send-tmps, &l, UTF8_ALLOW_ANYUV);
 	    tmps += UTF8SKIP(tmps);
 	    targlen += UNISKIP(~c);
 	    nchar++;
@@ -2450,7 +2426,7 @@ PP(pp_complement)
 	  if (nwide) {
 	      Newz(0, result, targlen + 1, U8);
 	      while (tmps < send) {
-		  UV c = utf8n_to_uvchr(tmps, send-tmps, &l, UTF8_ALLOW_ANYUV);
+		  const UV c = utf8n_to_uvchr(tmps, send-tmps, &l, UTF8_ALLOW_ANYUV);
 		  tmps += UTF8SKIP(tmps);
 		  result = uvchr_to_utf8_flags(result, ~c, UNICODE_ALLOW_ANY);
 	      }
@@ -2462,7 +2438,7 @@ PP(pp_complement)
 	  else {
 	      Newz(0, result, nchar + 1, U8);
 	      while (tmps < send) {
-		  U8 c = (U8)utf8n_to_uvchr(tmps, 0, &l, UTF8_ALLOW_ANY);
+		  const U8 c = (U8)utf8n_to_uvchr(tmps, 0, &l, UTF8_ALLOW_ANY);
 		  tmps += UTF8SKIP(tmps);
 		  *result++ = ~c;
 	      }
@@ -2713,10 +2689,8 @@ PP(pp_sin)
 {
     dSP; dTARGET; tryAMAGICun(sin);
     {
-      NV value;
-      value = POPn;
-      value = Perl_sin(value);
-      XPUSHn(value);
+      const NV value = POPn;
+      XPUSHn(Perl_sin(value));
       RETURN;
     }
 }
@@ -2725,10 +2699,8 @@ PP(pp_cos)
 {
     dSP; dTARGET; tryAMAGICun(cos);
     {
-      NV value;
-      value = POPn;
-      value = Perl_cos(value);
-      XPUSHn(value);
+      const NV value = POPn;
+      XPUSHn(Perl_cos(value));
       RETURN;
     }
 }
@@ -2797,14 +2769,12 @@ PP(pp_log)
 {
     dSP; dTARGET; tryAMAGICun(log);
     {
-      NV value;
-      value = POPn;
+      const NV value = POPn;
       if (value <= 0.0) {
 	SET_NUMERIC_STANDARD();
 	DIE(aTHX_ "Can't take log of %"NVgf, value);
       }
-      value = Perl_log(value);
-      XPUSHn(value);
+      XPUSHn(Perl_log(value));
       RETURN;
     }
 }
@@ -2813,14 +2783,12 @@ PP(pp_sqrt)
 {
     dSP; dTARGET; tryAMAGICun(sqrt);
     {
-      NV value;
-      value = POPn;
+      const NV value = POPn;
       if (value < 0.0) {
 	SET_NUMERIC_STANDARD();
 	DIE(aTHX_ "Can't take sqrt of %"NVgf, value);
       }
-      value = Perl_sqrt(value);
-      XPUSHn(value);
+      XPUSHn(Perl_sqrt(value));
       RETURN;
     }
 }
@@ -2829,8 +2797,7 @@ PP(pp_int)
 {
     dSP; dTARGET; tryAMAGICun(int);
     {
-      NV value;
-      IV iv = TOPi; /* attempt to convert to IV if possible. */
+      const IV iv = TOPi; /* attempt to convert to IV if possible. */
       /* XXX it's arguable that compiler casting to IV might be subtly
 	 different from modf (for numbers inside (IV_MIN,UV_MAX)) in which
 	 else preferring IV has introduced a subtle behaviour change bug. OTOH
@@ -2840,12 +2807,12 @@ PP(pp_int)
         SETu(0);
       else if (SvIOK(TOPs)) {
 	if (SvIsUV(TOPs)) {
-	    UV uv = TOPu;
+	    const UV uv = TOPu;
 	    SETu(uv);
 	} else
 	    SETi(iv);
       } else {
-	  value = TOPn;
+	  const NV value = TOPn;
 	  if (value >= 0.0) {
 	      if (value < (NV)UV_MAX + 0.5) {
 		  SETu(U_V(value));
@@ -2870,7 +2837,7 @@ PP(pp_abs)
     dSP; dTARGET; tryAMAGICun(abs);
     {
       /* This will cache the NV value if string isn't actually integer  */
-      IV iv = TOPi;
+      const IV iv = TOPi;
 
       if (!SvOK(TOPs))
         SETu(0);
@@ -2892,10 +2859,11 @@ PP(pp_abs)
 	  }
 	}
       } else{
-	NV value = TOPn;
+	const NV value = TOPn;
 	if (value < 0.0)
-	  value = -value;
-	SETn(value);
+	  SETn(value);
+	else
+	  SETn(-value);
       }
     }
     RETURN;
@@ -2910,13 +2878,13 @@ PP(pp_hex)
     STRLEN len;
     NV result_nv;
     UV result_uv;
-    SV* sv = POPs;
+    SV* const sv = POPs;
 
     tmps = (SvPV_const(sv, len));
     if (DO_UTF8(sv)) {
 	 /* If Unicode, try to downgrade
 	  * If not possible, croak. */
-         SV* tsv = sv_2mortal(newSVsv(sv));
+	 SV* const tsv = sv_2mortal(newSVsv(sv));
 	
 	 SvUTF8_on(tsv);
 	 sv_utf8_downgrade(tsv, FALSE);
@@ -2940,13 +2908,13 @@ PP(pp_oct)
     STRLEN len;
     NV result_nv;
     UV result_uv;
-    SV* sv = POPs;
+    SV* const sv = POPs;
 
     tmps = (SvPV_const(sv, len));
     if (DO_UTF8(sv)) {
 	 /* If Unicode, try to downgrade
 	  * If not possible, croak. */
-         SV* tsv = sv_2mortal(newSVsv(sv));
+	 SV* const tsv = sv_2mortal(newSVsv(sv));
 	
 	 SvUTF8_on(tsv);
 	 sv_utf8_downgrade(tsv, FALSE);
@@ -3002,7 +2970,7 @@ PP(pp_substr)
     SV *repl_sv = NULL;
     const char *repl = 0;
     STRLEN repl_len;
-    int num_args = PL_op->op_private & 7;
+    const int num_args = PL_op->op_private & 7;
     bool repl_need_utf8_upgrade = FALSE;
     bool repl_is_utf8 = FALSE;
 
@@ -3079,8 +3047,8 @@ PP(pp_substr)
 	RETPUSHUNDEF;
     }
     else {
-	I32 upos = pos;
-	I32 urem = rem;
+	const I32 upos = pos;
+	const I32 urem = rem;
 	if (utf8_curlen)
 	    sv_pos_u2b(sv, &pos, &rem);
 	tmps += pos;
@@ -3157,10 +3125,10 @@ PP(pp_substr)
 PP(pp_vec)
 {
     dSP; dTARGET;
-    register IV size   = POPi;
-    register IV offset = POPi;
-    register SV *src = POPs;
-    I32 lvalue = PL_op->op_flags & OPf_MOD || LVRET;
+    register const IV size   = POPi;
+    register const IV offset = POPi;
+    register SV * const src = POPs;
+    const I32 lvalue = PL_op->op_flags & OPf_MOD || LVRET;
 
     SvTAINTED_off(TARG);		/* decontaminate */
     if (lvalue) {			/* it's an lvalue! */
@@ -3196,7 +3164,7 @@ PP(pp_index)
     const char *tmps;
     const char *tmps2;
     STRLEN biglen;
-    I32 arybase = PL_curcop->cop_arybase;
+    const I32 arybase = PL_curcop->cop_arybase;
     int big_utf8;
     int little_utf8;
 
@@ -3210,9 +3178,9 @@ PP(pp_index)
     little_utf8 = DO_UTF8(little);
     if (big_utf8 ^ little_utf8) {
 	/* One needs to be upgraded.  */
-	SV *bytes = little_utf8 ? big : little;
+	SV * const bytes = little_utf8 ? big : little;
 	STRLEN len;
-	const char *p = SvPV_const(bytes, len);
+	const char * const p = SvPV_const(bytes, len);
 
 	temp = newSVpvn(p, len);
 
@@ -3260,7 +3228,7 @@ PP(pp_rindex)
     I32 retval;
     const char *tmps;
     const char *tmps2;
-    I32 arybase = PL_curcop->cop_arybase;
+    const I32 arybase = PL_curcop->cop_arybase;
     int big_utf8;
     int little_utf8;
 
@@ -3272,7 +3240,7 @@ PP(pp_rindex)
     little_utf8 = DO_UTF8(little);
     if (big_utf8 ^ little_utf8) {
 	/* One needs to be upgraded.  */
-	SV *bytes = little_utf8 ? big : little;
+	SV * const bytes = little_utf8 ? big : little;
 	STRLEN len;
 	const char *p = SvPV_const(bytes, len);
 
@@ -3418,7 +3386,7 @@ PP(pp_crypt)
          /* If Unicode, try to downgrade.
 	  * If not possible, croak.
 	  * Yes, we made this up.  */
-         SV* tsv = sv_2mortal(newSVsv(left));
+	 SV* const tsv = sv_2mortal(newSVsv(left));
 
 	 SvUTF8_on(tsv);
 	 sv_utf8_downgrade(tsv, FALSE);
@@ -3689,8 +3657,8 @@ PP(pp_lc)
 	    d = (U8*)SvPVX(TARG);
 	    send = s + len;
 	    while (s < send) {
-		STRLEN u = UTF8SKIP(s);
-		UV uv = toLOWER_utf8(s, tmpbuf, &ulen);
+		const STRLEN u = UTF8SKIP(s);
+		const UV uv = toLOWER_utf8(s, tmpbuf, &ulen);
 
 #define GREEK_CAPITAL_LETTER_SIGMA 0x03A3 /* Unicode U+03A3 */
 		if (uv == GREEK_CAPITAL_LETTER_SIGMA) {
@@ -3745,7 +3713,7 @@ PP(pp_lc)
 
 	s = (U8*)SvPV_force_nomg(sv, len);
 	if (len) {
-	    register U8 *send = s + len;
+	    register const U8 * const send = s + len;
 
 	    if (IN_LOCALE_RUNTIME) {
 		TAINT;
@@ -3766,13 +3734,13 @@ PP(pp_lc)
 PP(pp_quotemeta)
 {
     dSP; dTARGET;
-    SV *sv = TOPs;
+    SV * const sv = TOPs;
     STRLEN len;
     const register char *s = SvPV_const(sv,len);
-    register char *d;
 
     SvUTF8_off(TARG);				/* decontaminate */
     if (len) {
+	register char *d;
 	SvUPGRADE(TARG, SVt_PV);
 	SvGROW(TARG, (len * 2) + 1);
 	d = SvPVX(TARG);
@@ -3819,17 +3787,16 @@ PP(pp_quotemeta)
 PP(pp_aslice)
 {
     dSP; dMARK; dORIGMARK;
-    register SV** svp;
-    register AV* av = (AV*)POPs;
-    register I32 lval = (PL_op->op_flags & OPf_MOD || LVRET);
-    I32 arybase = PL_curcop->cop_arybase;
-    I32 elem;
+    register AV* const av = (AV*)POPs;
+    register const I32 lval = (PL_op->op_flags & OPf_MOD || LVRET);
 
     if (SvTYPE(av) == SVt_PVAV) {
+	const I32 arybase = PL_curcop->cop_arybase;
 	if (lval && PL_op->op_private & OPpLVAL_INTRO) {
+	    register SV **svp;
 	    I32 max = -1;
 	    for (svp = MARK + 1; svp <= SP; svp++) {
-		elem = SvIVx(*svp);
+		const I32 elem = SvIVx(*svp);
 		if (elem > max)
 		    max = elem;
 	    }
@@ -3837,7 +3804,8 @@ PP(pp_aslice)
 		av_extend(av, max);
 	}
 	while (++MARK <= SP) {
-	    elem = SvIVx(*MARK);
+	    register SV **svp;
+	    I32 elem = SvIVx(*MARK);
 
 	    if (elem > 0)
 		elem -= arybase;
@@ -3864,7 +3832,7 @@ PP(pp_aslice)
 PP(pp_each)
 {
     dSP;
-    HV *hash = (HV*)POPs;
+    HV * const hash = (HV*)POPs;
     HE *entry;
     const I32 gimme = GIMME_V;
 
@@ -3875,7 +3843,7 @@ PP(pp_each)
 
     EXTEND(SP, 2);
     if (entry) {
-        SV* sv = hv_iterkeysv(entry);
+	SV* const sv = hv_iterkeysv(entry);
 	PUSHs(sv);	/* won't clobber stack_sp */
 	if (gimme == G_ARRAY) {
 	    SV *val;
@@ -3907,24 +3875,21 @@ PP(pp_delete)
     dSP;
     const I32 gimme = GIMME_V;
     const I32 discard = (gimme == G_VOID) ? G_DISCARD : 0;
-    SV *sv;
-    HV *hv;
 
     if (PL_op->op_private & OPpSLICE) {
 	dMARK; dORIGMARK;
-	U32 hvtype;
-	hv = (HV*)POPs;
-	hvtype = SvTYPE(hv);
+	HV * const hv = (HV*)POPs;
+	const U32 hvtype = SvTYPE(hv);
 	if (hvtype == SVt_PVHV) {			/* hash element */
 	    while (++MARK <= SP) {
-		sv = hv_delete_ent(hv, *MARK, discard, 0);
+		SV * const sv = hv_delete_ent(hv, *MARK, discard, 0);
 		*MARK = sv ? sv : &PL_sv_undef;
 	    }
 	}
 	else if (hvtype == SVt_PVAV) {                  /* array element */
             if (PL_op->op_flags & OPf_SPECIAL) {
                 while (++MARK <= SP) {
-                    sv = av_delete((AV*)hv, SvIV(*MARK), discard);
+                    SV * const sv = av_delete((AV*)hv, SvIV(*MARK), discard);
                     *MARK = sv ? sv : &PL_sv_undef;
                 }
             }
@@ -3944,7 +3909,8 @@ PP(pp_delete)
     }
     else {
 	SV *keysv = POPs;
-	hv = (HV*)POPs;
+	HV * const hv = (HV*)POPs;
+	SV *sv;
 	if (SvTYPE(hv) == SVt_PVHV)
 	    sv = hv_delete_ent(hv, keysv, discard, 0);
 	else if (SvTYPE(hv) == SVt_PVAV) {
@@ -3971,9 +3937,8 @@ PP(pp_exists)
 
     if (PL_op->op_private & OPpEXISTS_SUB) {
 	GV *gv;
-	CV *cv;
 	SV *sv = POPs;
-	cv = sv_2cv(sv, &hv, &gv, FALSE);
+	CV * const cv = sv_2cv(sv, &hv, &gv, FALSE);
 	if (cv)
 	    RETPUSHYES;
 	if (gv && isGV(gv) && GvCV(gv) && !GvCVGEN(gv))
@@ -4001,9 +3966,9 @@ PP(pp_exists)
 PP(pp_hslice)
 {
     dSP; dMARK; dORIGMARK;
-    register HV *hv = (HV*)POPs;
-    register I32 lval = (PL_op->op_flags & OPf_MOD || LVRET);
-    bool localizing = PL_op->op_private & OPpLVAL_INTRO ? TRUE : FALSE;
+    register HV * const hv = (HV*)POPs;
+    register const I32 lval = (PL_op->op_flags & OPf_MOD || LVRET);
+    const bool localizing = PL_op->op_private & OPpLVAL_INTRO;
     bool other_magic = FALSE;
 
     if (localizing) {
@@ -4021,7 +3986,7 @@ PP(pp_hslice)
     }
 
     while (++MARK <= SP) {
-        SV *keysv = *MARK;
+        SV * const keysv = *MARK;
         SV **svp;
         HE *he;
         bool preeminent = FALSE;
@@ -4076,20 +4041,18 @@ PP(pp_list)
 PP(pp_lslice)
 {
     dSP;
-    SV **lastrelem = PL_stack_sp;
-    SV **lastlelem = PL_stack_base + POPMARK;
-    SV **firstlelem = PL_stack_base + POPMARK + 1;
-    register SV **firstrelem = lastlelem + 1;
-    I32 arybase = PL_curcop->cop_arybase;
-    I32 lval = PL_op->op_flags & OPf_MOD;
-    I32 is_something_there = lval;
-
-    register I32 max = lastrelem - lastlelem;
+    SV ** const lastrelem = PL_stack_sp;
+    SV ** const lastlelem = PL_stack_base + POPMARK;
+    SV ** const firstlelem = PL_stack_base + POPMARK + 1;
+    register SV ** const firstrelem = lastlelem + 1;
+    const I32 arybase = PL_curcop->cop_arybase;
+    I32 is_something_there = PL_op->op_flags & OPf_MOD;
+
+    register const I32 max = lastrelem - lastlelem;
     register SV **lelem;
-    register I32 ix;
 
     if (GIMME != G_ARRAY) {
-	ix = SvIVx(*lastlelem);
+	I32 ix = SvIVx(*lastlelem);
 	if (ix < 0)
 	    ix += max;
 	else
@@ -4108,7 +4071,7 @@ PP(pp_lslice)
     }
 
     for (lelem = firstlelem; lelem <= lastlelem; lelem++) {
-	ix = SvIVx(*lelem);
+	I32 ix = SvIVx(*lelem);
 	if (ix < 0)
 	    ix += max;
 	else
@@ -4131,8 +4094,8 @@ PP(pp_lslice)
 PP(pp_anonlist)
 {
     dSP; dMARK; dORIGMARK;
-    I32 items = SP - MARK;
-    SV *av = sv_2mortal((SV*)av_make(items, MARK+1));
+    const I32 items = SP - MARK;
+    SV * const av = sv_2mortal((SV*)av_make(items, MARK+1));
     SP = ORIGMARK;		/* av_make() might realloc stack_sp */
     XPUSHs(av);
     RETURN;
@@ -4141,11 +4104,11 @@ PP(pp_anonlist)
 PP(pp_anonhash)
 {
     dSP; dMARK; dORIGMARK;
-    HV* hv = (HV*)sv_2mortal((SV*)newHV());
+    HV* const hv = (HV*)sv_2mortal((SV*)newHV());
 
     while (MARK < SP) {
-	SV* key = *++MARK;
-	SV *val = NEWSV(46, 0);
+	SV * const key = *++MARK;
+	SV * const val = NEWSV(46, 0);
 	if (MARK < SP)
 	    sv_setsv(val, *++MARK);
 	else if (ckWARN(WARN_MISC))
@@ -4170,9 +4133,9 @@ PP(pp_splice)
     I32 after;
     I32 diff;
     SV **tmparyval = 0;
-    MAGIC *mg;
+    const MAGIC * const mg = SvTIED_mg((SV*)ary, PERL_MAGIC_tied);
 
-    if ((mg = SvTIED_mg((SV*)ary, PERL_MAGIC_tied))) {
+    if (mg) {
 	*MARK-- = SvTIED_obj((SV*)ary, mg);
 	PUSHMARK(MARK);
 	PUTBACK;
@@ -4230,7 +4193,7 @@ PP(pp_splice)
 
     /* make new elements SVs now: avoid problems if they're from the array */
     for (dst = MARK, i = newlen; i; i--) {
-        SV *h = *dst;
+        SV * const h = *dst;
 	*dst++ = newSVsv(h);
     }
 
@@ -4368,10 +4331,9 @@ PP(pp_push)
 {
     dVAR; dSP; dMARK; dORIGMARK; dTARGET;
     register AV *ary = (AV*)*++MARK;
-    register SV *sv = &PL_sv_undef;
-    MAGIC *mg;
+    const MAGIC * const mg = SvTIED_mg((SV*)ary, PERL_MAGIC_tied);
 
-    if ((mg = SvTIED_mg((SV*)ary, PERL_MAGIC_tied))) {
+    if (mg) {
 	*MARK-- = SvTIED_obj((SV*)ary, mg);
 	PUSHMARK(MARK);
 	PUTBACK;
@@ -4383,7 +4345,7 @@ PP(pp_push)
     else {
 	/* Why no pre-extend of ary here ? */
 	for (++MARK; MARK <= SP; MARK++) {
-	    sv = NEWSV(51, 0);
+	    SV * const sv = NEWSV(51, 0);
 	    if (*MARK)
 		sv_setsv(sv, *MARK);
 	    av_push(ary, sv);
@@ -4397,8 +4359,8 @@ PP(pp_push)
 PP(pp_pop)
 {
     dSP;
-    AV *av = (AV*)POPs;
-    SV *sv = av_pop(av);
+    AV * const av = (AV*)POPs;
+    SV * const sv = av_pop(av);
     if (AvREAL(av))
 	(void)sv_2mortal(sv);
     PUSHs(sv);
@@ -4408,8 +4370,8 @@ PP(pp_pop)
 PP(pp_shift)
 {
     dSP;
-    AV *av = (AV*)POPs;
-    SV *sv = av_shift(av);
+    AV * const av = (AV*)POPs;
+    SV * const sv = av_shift(av);
     EXTEND(SP, 1);
     if (!sv)
 	RETPUSHUNDEF;
@@ -4423,11 +4385,9 @@ PP(pp_unshift)
 {
     dVAR; dSP; dMARK; dORIGMARK; dTARGET;
     register AV *ary = (AV*)*++MARK;
-    register SV *sv;
-    register I32 i = 0;
-    MAGIC *mg;
+    const MAGIC * const mg = SvTIED_mg((SV*)ary, PERL_MAGIC_tied);
 
-    if ((mg = SvTIED_mg((SV*)ary, PERL_MAGIC_tied))) {
+    if (mg) {
 	*MARK-- = SvTIED_obj((SV*)ary, mg);
 	PUSHMARK(MARK);
 	PUTBACK;
@@ -4437,9 +4397,10 @@ PP(pp_unshift)
 	SPAGAIN;
     }
     else {
+	register I32 i = 0;
 	av_unshift(ary, SP - MARK);
 	while (MARK < SP) {
-	    sv = newSVsv(*++MARK);
+	    SV * const sv = newSVsv(*++MARK);
 	    (void)av_store(ary, i++, sv);
 	}
     }
@@ -4451,13 +4412,12 @@ PP(pp_unshift)
 PP(pp_reverse)
 {
     dSP; dMARK;
-    register SV *tmp;
-    SV **oldsp = SP;
+    SV ** const oldsp = SP;
 
     if (GIMME == G_ARRAY) {
 	MARK++;
 	while (MARK < SP) {
-	    tmp = *MARK;
+	    register SV * const tmp = *MARK;
 	    *MARK++ = *SP;
 	    *SP-- = tmp;
 	}
@@ -4526,10 +4486,10 @@ PP(pp_split)
     dVAR; dSP; dTARG;
     AV *ary;
     register IV limit = POPi;			/* note, negative is forever */
-    SV *sv = POPs;
+    SV * const sv = POPs;
     STRLEN len;
     register const char *s = SvPV_const(sv, len);
-    bool do_utf8 = DO_UTF8(sv);
+    const bool do_utf8 = DO_UTF8(sv);
     const char *strend = s + len;
     register PMOP *pm;
     register REGEXP *rx;
@@ -4538,9 +4498,8 @@ PP(pp_split)
     I32 iters = 0;
     const STRLEN slen = do_utf8 ? utf8_length((U8*)s, (U8*)strend) : (strend - s);
     I32 maxiters = slen + 10;
-    I32 i;
     const char *orig;
-    I32 origlimit = limit;
+    const I32 origlimit = limit;
     I32 realarray = 0;
     I32 base;
     const I32 gimme = GIMME_V;
@@ -4586,6 +4545,7 @@ PP(pp_split)
 	}
 	else {
 	    if (!AvREAL(ary)) {
+		I32 i;
 		AvREAL_on(ary);
 		AvREIFY_off(ary);
 		for (i = AvFILLp(ary); i >= 0; i--)
@@ -4658,12 +4618,12 @@ PP(pp_split)
 	     (rx->reganch & RE_USE_INTUIT) && !rx->nparens
 	     && (rx->reganch & ROPT_CHECK_ALL)
 	     && !(rx->reganch & ROPT_ANCH)) {
-	int tail = (rx->reganch & RE_INTUIT_TAIL);
-	SV *csv = CALLREG_INTUIT_STRING(aTHX_ rx);
+	const int tail = (rx->reganch & RE_INTUIT_TAIL);
+	SV * const csv = CALLREG_INTUIT_STRING(aTHX_ rx);
 
 	len = rx->minlen;
 	if (len == 1 && !(rx->reganch & ROPT_UTF8) && !tail) {
-	    char c = *SvPV_nolen_const(csv);
+	    const char c = *SvPV_nolen_const(csv);
 	    while (--limit) {
 		for (m = s; m < strend && *m != c; m++)
 		    ;
@@ -4707,11 +4667,12 @@ PP(pp_split)
 	maxiters += slen * rx->nparens;
 	while (s < strend && --limit)
 	{
+	    I32 rex_return;
 	    PUTBACK;
-	    i = CALLREGEXEC(aTHX_ rx, (char*)s, (char*)strend, (char*)orig, 1 ,
+	    rex_return = CALLREGEXEC(aTHX_ rx, (char*)s, (char*)strend, (char*)orig, 1 ,
 			    sv, NULL, 0);
 	    SPAGAIN;
-	    if (i == 0)
+	    if (rex_return == 0)
 		break;
 	    TAINT_IF(RX_MATCH_TAINTED(rx));
 	    if (RX_MATCH_COPIED(rx) && rx->subbeg != orig) {
@@ -4729,6 +4690,7 @@ PP(pp_split)
 		(void)SvUTF8_on(dstr);
 	    XPUSHs(dstr);
 	    if (rx->nparens) {
+		I32 i;
 		for (i = 1; i <= (I32)rx->nparens; i++) {
 		    s = rx->startp[i] + orig;
 		    m = rx->endp[i] + orig;
@@ -4758,7 +4720,7 @@ PP(pp_split)
 
     /* keep field after final delim? */
     if (s < strend || (iters && origlimit)) {
-        STRLEN l = strend - s;
+        const STRLEN l = strend - s;
 	dstr = newSVpvn(s, l);
 	if (make_mortal)
 	    sv_2mortal(dstr);
@@ -4800,6 +4762,7 @@ PP(pp_split)
 	    LEAVE;
 	    SPAGAIN;
 	    if (gimme == G_ARRAY) {
+		I32 i;
 		/* EXTEND should not be needed - we just popped them */
 		EXTEND(SP, iters);
 		for (i=0; i < iters; i++) {
diff --git a/pp.h b/pp.h
index 8f127d1208..d5e3bf9277 100644
--- a/pp.h
+++ b/pp.h
@@ -283,8 +283,8 @@ and C<PUSHu>.
 			} } STMT_END
 
 /* Same thing, but update mark register too. */
-#define MEXTEND(p,n)	STMT_START {if (PL_stack_max - p < (int)(n)) {		\
-			    int markoff = mark - PL_stack_base;		\
+#define MEXTEND(p,n)	STMT_START {if (PL_stack_max - p < (int)(n)) {	\
+			    const int markoff = mark - PL_stack_base;	\
 			    sp = stack_grow(sp,p,(int) (n));		\
 			    mark = PL_stack_base + markoff;		\
 			} } STMT_END
@@ -401,7 +401,7 @@ and C<PUSHu>.
 #define tryAMAGICbinW(meth,assign,set) STMT_START { \
           if (PL_amagic_generation) { \
 	    SV* tmpsv; \
-	    SV* right= *(sp); SV* left= *(sp-1);\
+	    SV* const right= *(sp); SV* const left= *(sp-1);\
 	    if ((SvAMAGIC(left)||SvAMAGIC(right))&&\
 		(tmpsv=amagic_call(left, \
 				   right, \
@@ -483,3 +483,13 @@ True if this op will be the return value of an lvalue subroutine
 
 =cut */
 #define LVRET ((PL_op->op_private & OPpMAYBE_LVSUB) && is_lvalue_sub())
+
+/*
+ * Local variables:
+ * c-indentation-style: bsd
+ * c-basic-offset: 4
+ * indent-tabs-mode: t
+ * End:
+ *
+ * ex: set ts=8 sts=4 sw=4 noet:
+ */
diff --git a/pp_ctl.c b/pp_ctl.c
index 94a3f31ab6..e27d637a76 100644
--- a/pp_ctl.c
+++ b/pp_ctl.c
@@ -1374,6 +1374,7 @@ Perl_dounwind(pTHX_ I32 cxix)
 	}
 	cxstack_ix--;
     }
+    PERL_UNUSED_VAR(optype);
 }
 
 void
@@ -2068,6 +2069,7 @@ PP(pp_last)
 	dounwind(cxix);
 
     POPBLOCK(cx,newpm);
+    PERL_UNUSED_VAR(optype);
     cxstack_ix++; /* temporarily protect top context */
     mark = newsp;
     switch (CxTYPE(cx)) {
@@ -2380,6 +2382,9 @@ PP(pp_goto)
 		    PUSHMARK(mark);
 		    PUTBACK;
 		    (void)(*CvXSUB(cv))(aTHX_ cv);
+		    /* Put these at the bottom since the vars are set but not used */
+		    PERL_UNUSED_VAR(newsp);
+		    PERL_UNUSED_VAR(gimme);
 		}
 		LEAVE;
 		return retop;
@@ -2857,7 +2862,7 @@ Perl_find_runcv(pTHX_ U32 *db_seqp)
 	for (ix = si->si_cxix; ix >= 0; ix--) {
 	    const PERL_CONTEXT *cx = &(si->si_cxstack[ix]);
 	    if (CxTYPE(cx) == CXt_SUB || CxTYPE(cx) == CXt_FORMAT) {
-		CV *cv = cx->blk_sub.cv;
+		CV * const cv = cx->blk_sub.cv;
 		/* skip DB:: code */
 		if (db_seqp && PL_debstash && CvSTASH(cv) == PL_debstash) {
 		    *db_seqp = cx->blk_oldcop->cop_seq;
diff --git a/pp_sys.c b/pp_sys.c
index 68f72271ac..e096478b3b 100644
--- a/pp_sys.c
+++ b/pp_sys.c
@@ -321,7 +321,7 @@ PP(pp_backtick)
 {
     dSP; dTARGET;
     PerlIO *fp;
-    const char *tmps = POPpconstx;
+    const char * const tmps = POPpconstx;
     const I32 gimme = GIMME_V;
     const char *mode = "r";
 
@@ -356,10 +356,8 @@ PP(pp_backtick)
 	    SvTAINTED_on(TARG);
 	}
 	else {
-	    SV *sv;
-
 	    for (;;) {
-		sv = NEWSV(56, 79);
+		SV * const sv = NEWSV(56, 79);
 		if (sv_gets(sv, fp, 0) == Nullch) {
 		    SvREFCNT_dec(sv);
 		    break;
@@ -445,7 +443,7 @@ PP(pp_warn)
     }
     tmps = SvPV_const(tmpsv, len);
     if ((!tmps || !len) && PL_errgv) {
-  	SV *error = ERRSV;
+  	SV * const error = ERRSV;
 	SvUPGRADE(error, SVt_PV);
 	if (SvPOK(error) && SvCUR(error))
 	    sv_catpv(error, "\t...caught");
@@ -882,7 +880,7 @@ PP(pp_untie)
 	RETPUSHYES;
 
     if ((mg = SvTIED_mg(sv, how))) {
-	SV *obj = SvRV(SvTIED_obj(sv, mg));
+	SV * const obj = SvRV(SvTIED_obj(sv, mg));
 	GV *gv;
 	CV *cv = NULL;
         if (obj) {
@@ -912,7 +910,7 @@ PP(pp_untie)
 PP(pp_tied)
 {
     dSP;
-    MAGIC *mg;
+    const MAGIC *mg;
     SV *sv = POPs;
     const char how = (SvTYPE(sv) == SVt_PVHV || SvTYPE(sv) == SVt_PVAV)
 		? PERL_MAGIC_tied : PERL_MAGIC_tiedscalar;
@@ -933,13 +931,12 @@ PP(pp_tied)
 PP(pp_dbmopen)
 {
     dVAR; dSP;
-    HV *hv;
     dPOPPOPssrl;
     HV* stash;
     GV *gv;
     SV *sv;
 
-    hv = (HV*)POPs;
+    HV * const hv = (HV*)POPs;
 
     sv = sv_mortalcopy(&PL_sv_no);
     sv_setpv(sv, "AnyDBM_File");
@@ -1181,7 +1178,7 @@ PP(pp_select)
     if (! hv)
 	XPUSHs(&PL_sv_undef);
     else {
-	GV **gvp = (GV**)hv_fetch(hv, GvNAME(egv), GvNAMELEN(egv), FALSE);
+	GV ** const gvp = (GV**)hv_fetch(hv, GvNAME(egv), GvNAMELEN(egv), FALSE);
 	if (gvp && *gvp == egv) {
 	    gv_efullname4(TARG, PL_defoutgv, Nullch, TRUE);
 	    XPUSHTARG;
@@ -1203,14 +1200,9 @@ PP(pp_select)
 PP(pp_getc)
 {
     dVAR; dSP; dTARGET;
-    GV *gv;
     IO *io = NULL;
     MAGIC *mg;
-
-    if (MAXARG == 0)
-	gv = PL_stdingv;
-    else
-	gv = (GV*)POPs;
+    GV * const gv = (MAXARG==0) ? PL_stdingv : (GV*)POPs;
 
     if (gv && (io = GvIO(gv))
 	&& (mg = SvTIED_mg((SV*)io, PERL_MAGIC_tiedscalar)))
@@ -1322,13 +1314,15 @@ PP(pp_enterwrite)
 PP(pp_leavewrite)
 {
     dVAR; dSP;
-    GV *gv = cxstack[cxstack_ix].blk_sub.gv;
-    register IO *io = GvIOp(gv);
-    PerlIO *ofp = IoOFP(io);
+    GV * const gv = cxstack[cxstack_ix].blk_sub.gv;
+    register IO * const io = GvIOp(gv);
+    PerlIO * const ofp = IoOFP(io);
     PerlIO *fp;
     SV **newsp;
     I32 gimme;
     register PERL_CONTEXT *cx;
+    PERL_UNUSED_VAR(newsp);
+    PERL_UNUSED_VAR(gimme);
 
     DEBUG_f(PerlIO_printf(Perl_debug_log, "left=%ld, todo=%ld\n",
 	  (long)IoLINES_LEFT(io), (long)FmLINES(PL_formtarget)));
@@ -1341,9 +1335,9 @@ PP(pp_leavewrite)
 	CV *cv;
 	if (!IoTOP_GV(io)) {
 	    GV *topgv;
-	    SV *topname;
 
 	    if (!IoTOP_NAME(io)) {
+		SV *topname;
 		if (!IoFMT_NAME(io))
 		    IoFMT_NAME(io) = savepv(GvNAME(gv));
 		topname = sv_2mortal(Perl_newSVpvf(aTHX_ "%s_TOP", GvNAME(gv)));
@@ -1522,19 +1516,14 @@ PP(pp_prtf)
 PP(pp_sysopen)
 {
     dSP;
-    GV *gv;
-    SV *sv;
-    const char *tmps;
-    STRLEN len;
     const int perm = (MAXARG > 3) ? POPi : 0666;
     const int mode = POPi;
-
-    sv = POPs;
-    gv = (GV *)POPs;
+    SV * const sv = POPs;
+    GV * const gv = (GV *)POPs;
+    STRLEN len;
 
     /* Need TIEHANDLE method ? */
-
-    tmps = SvPV_const(sv, len);
+    const char * const tmps = SvPV_const(sv, len);
     /* FIXME? do_open should do const  */
     if (do_open(gv, (char*)tmps, len, TRUE, mode, perm, Nullfp)) {
 	IoLINES(GvIOp(gv)) = 0;
@@ -1550,7 +1539,6 @@ PP(pp_sysread)
 {
     dVAR; dSP; dMARK; dORIGMARK; dTARGET;
     int offset;
-    GV *gv;
     IO *io;
     char *buffer;
     SSize_t length;
@@ -1558,7 +1546,6 @@ PP(pp_sysread)
     Sock_size_t bufsize;
     SV *bufsv;
     STRLEN blen;
-    MAGIC *mg;
     int fp_utf8;
     int buffer_utf8;
     SV *read_target;
@@ -1568,23 +1555,24 @@ PP(pp_sysread)
     STRLEN charskip = 0;
     STRLEN skip = 0;
 
-    gv = (GV*)*++MARK;
+    GV * const gv = (GV*)*++MARK;
     if ((PL_op->op_type == OP_READ || PL_op->op_type == OP_SYSREAD)
-	&& gv && (io = GvIO(gv))
-	&& (mg = SvTIED_mg((SV*)io, PERL_MAGIC_tiedscalar)))
+	&& gv && (io = GvIO(gv)) )
     {
-	SV *sv;
-	
-	PUSHMARK(MARK-1);
-	*MARK = SvTIED_obj((SV*)io, mg);
-	ENTER;
-	call_method("READ", G_SCALAR);
-	LEAVE;
-	SPAGAIN;
-	sv = POPs;
-	SP = ORIGMARK;
-	PUSHs(sv);
-	RETURN;
+	const MAGIC * mg = SvTIED_mg((SV*)io, PERL_MAGIC_tiedscalar);
+	if (mg) {
+	    SV *sv;
+	    PUSHMARK(MARK-1);
+	    *MARK = SvTIED_obj((SV*)io, mg);
+	    ENTER;
+	    call_method("READ", G_SCALAR);
+	    LEAVE;
+	    SPAGAIN;
+	    sv = POPs;
+	    SP = ORIGMARK;
+	    PUSHs(sv);
+	    RETURN;
+	}
     }
 
     if (!gv)
diff --git a/proto.h b/proto.h
index 22f84e7a0d..cc7f00bf48 100644
--- a/proto.h
+++ b/proto.h
@@ -80,9 +80,7 @@ PERL_CALLCONV OP*	Perl_append_list(pTHX_ I32 optype, LISTOP* first, LISTOP* last
 PERL_CALLCONV I32	Perl_apply(pTHX_ I32 type, SV** mark, SV** sp);
 PERL_CALLCONV void	Perl_apply_attrs_string(pTHX_ const char *stashpv, CV *cv, const char *attrstr, STRLEN len);
 PERL_CALLCONV void	Perl_av_clear(pTHX_ AV* ar);
-PERL_CALLCONV SV*	Perl_av_delete(pTHX_ AV* ar, I32 key, I32 flags)
-			__attribute__warn_unused_result__;
-
+PERL_CALLCONV SV*	Perl_av_delete(pTHX_ AV* ar, I32 key, I32 flags);
 PERL_CALLCONV bool	Perl_av_exists(pTHX_ AV* ar, I32 key)
 			__attribute__warn_unused_result__;
 
@@ -104,9 +102,7 @@ PERL_CALLCONV AV*	Perl_av_make(pTHX_ I32 size, SV** svp)
 			__attribute__warn_unused_result__
 			__attribute__nonnull__(pTHX_2);
 
-PERL_CALLCONV SV*	Perl_av_pop(pTHX_ AV* ar)
-			__attribute__warn_unused_result__;
-
+PERL_CALLCONV SV*	Perl_av_pop(pTHX_ AV* ar);
 PERL_CALLCONV void	Perl_av_push(pTHX_ AV* ar, SV* val);
 PERL_CALLCONV void	Perl_av_reify(pTHX_ AV* ar);
 PERL_CALLCONV SV*	Perl_av_shift(pTHX_ AV* ar)
@@ -403,7 +399,6 @@ PERL_CALLCONV void	Perl_gv_fullname(pTHX_ SV* sv, const GV* gv);
 PERL_CALLCONV void	Perl_gv_fullname4(pTHX_ SV* sv, const GV* gv, const char* prefix, bool keepmain);
 PERL_CALLCONV void	Perl_gv_init(pTHX_ GV* gv, HV* stash, const char* name, STRLEN len, int multi)
 			__attribute__nonnull__(pTHX_1)
-			__attribute__nonnull__(pTHX_2)
 			__attribute__nonnull__(pTHX_3);
 
 PERL_CALLCONV HV*	Perl_gv_stashpv(pTHX_ const char* name, I32 create);
@@ -1089,7 +1084,8 @@ PERL_CALLCONV SV*	Perl_newSVpvf(pTHX_ const char* pat, ...)
 PERL_CALLCONV SV*	Perl_vnewSVpvf(pTHX_ const char* pat, va_list* args);
 PERL_CALLCONV SV*	Perl_newSVrv(pTHX_ SV* rv, const char* classname)
 			__attribute__malloc__
-			__attribute__warn_unused_result__;
+			__attribute__warn_unused_result__
+			__attribute__nonnull__(pTHX_1);
 
 PERL_CALLCONV SV*	Perl_newSVsv(pTHX_ SV* old)
 			__attribute__malloc__
@@ -1553,7 +1549,8 @@ PERL_CALLCONV MAGIC *	Perl_sv_magicext(pTHX_ SV* sv, SV* obj, int how, const MGV
 			__attribute__nonnull__(pTHX_1);
 
 PERL_CALLCONV SV*	Perl_sv_mortalcopy(pTHX_ SV* oldsv)
-			__attribute__nonnull__(pTHX_1);
+			__attribute__malloc__
+			__attribute__warn_unused_result__;
 
 PERL_CALLCONV SV*	Perl_sv_newmortal(pTHX)
 			__attribute__warn_unused_result__;
@@ -1597,7 +1594,9 @@ PERL_CALLCONV SV*	Perl_sv_setref_iv(pTHX_ SV* rv, const char* classname, IV iv);
 PERL_CALLCONV SV*	Perl_sv_setref_uv(pTHX_ SV* rv, const char* classname, UV uv);
 PERL_CALLCONV SV*	Perl_sv_setref_nv(pTHX_ SV* rv, const char* classname, NV nv);
 PERL_CALLCONV SV*	Perl_sv_setref_pv(pTHX_ SV* rv, const char* classname, void* pv);
-PERL_CALLCONV SV*	Perl_sv_setref_pvn(pTHX_ SV* rv, const char* classname, char* pv, STRLEN n);
+PERL_CALLCONV SV*	Perl_sv_setref_pvn(pTHX_ SV* rv, const char* classname, const char* pv, STRLEN n)
+			__attribute__nonnull__(pTHX_3);
+
 PERL_CALLCONV void	Perl_sv_setpv(pTHX_ SV* sv, const char* ptr);
 PERL_CALLCONV void	Perl_sv_setpvn(pTHX_ SV* sv, const char* ptr, STRLEN len)
 			__attribute__nonnull__(pTHX_1);
@@ -1782,16 +1781,33 @@ PERL_CALLCONV void	Perl_sv_usepvn_mg(pTHX_ SV *sv, char *ptr, STRLEN len);
 PERL_CALLCONV MGVTBL*	Perl_get_vtbl(pTHX_ int vtbl_id);
 PERL_CALLCONV char*	Perl_pv_display(pTHX_ SV *dsv, const char *pv, STRLEN cur, STRLEN len, STRLEN pvlim);
 PERL_CALLCONV void	Perl_dump_indent(pTHX_ I32 level, PerlIO *file, const char* pat, ...)
-			__attribute__format__(__printf__,pTHX_3,pTHX_4);
-
-PERL_CALLCONV void	Perl_dump_vindent(pTHX_ I32 level, PerlIO *file, const char* pat, va_list *args);
-PERL_CALLCONV void	Perl_do_gv_dump(pTHX_ I32 level, PerlIO *file, const char *name, GV *sv);
-PERL_CALLCONV void	Perl_do_gvgv_dump(pTHX_ I32 level, PerlIO *file, const char *name, GV *sv);
-PERL_CALLCONV void	Perl_do_hv_dump(pTHX_ I32 level, PerlIO *file, const char *name, HV *sv);
-PERL_CALLCONV void	Perl_do_magic_dump(pTHX_ I32 level, PerlIO *file, const MAGIC *mg, I32 nest, I32 maxnest, bool dumpops, STRLEN pvlim);
-PERL_CALLCONV void	Perl_do_op_dump(pTHX_ I32 level, PerlIO *file, const OP *o);
-PERL_CALLCONV void	Perl_do_pmop_dump(pTHX_ I32 level, PerlIO *file, const PMOP *pm);
-PERL_CALLCONV void	Perl_do_sv_dump(pTHX_ I32 level, PerlIO *file, SV *sv, I32 nest, I32 maxnest, bool dumpops, STRLEN pvlim);
+			__attribute__format__(__printf__,pTHX_3,pTHX_4)
+			__attribute__nonnull__(pTHX_2);
+
+PERL_CALLCONV void	Perl_dump_vindent(pTHX_ I32 level, PerlIO *file, const char* pat, va_list *args)
+			__attribute__nonnull__(pTHX_2);
+
+PERL_CALLCONV void	Perl_do_gv_dump(pTHX_ I32 level, PerlIO *file, const char *name, GV *sv)
+			__attribute__nonnull__(pTHX_2);
+
+PERL_CALLCONV void	Perl_do_gvgv_dump(pTHX_ I32 level, PerlIO *file, const char *name, GV *sv)
+			__attribute__nonnull__(pTHX_2);
+
+PERL_CALLCONV void	Perl_do_hv_dump(pTHX_ I32 level, PerlIO *file, const char *name, HV *sv)
+			__attribute__nonnull__(pTHX_2);
+
+PERL_CALLCONV void	Perl_do_magic_dump(pTHX_ I32 level, PerlIO *file, const MAGIC *mg, I32 nest, I32 maxnest, bool dumpops, STRLEN pvlim)
+			__attribute__nonnull__(pTHX_2);
+
+PERL_CALLCONV void	Perl_do_op_dump(pTHX_ I32 level, PerlIO *file, const OP *o)
+			__attribute__nonnull__(pTHX_2);
+
+PERL_CALLCONV void	Perl_do_pmop_dump(pTHX_ I32 level, PerlIO *file, const PMOP *pm)
+			__attribute__nonnull__(pTHX_2);
+
+PERL_CALLCONV void	Perl_do_sv_dump(pTHX_ I32 level, PerlIO *file, SV *sv, I32 nest, I32 maxnest, bool dumpops, STRLEN pvlim)
+			__attribute__nonnull__(pTHX_2);
+
 PERL_CALLCONV void	Perl_magic_dump(pTHX_ const MAGIC *mg);
 PERL_CALLCONV void	Perl_reginitcolors(pTHX);
 PERL_CALLCONV char*	Perl_sv_2pv_nolen(pTHX_ SV* sv);
@@ -1986,7 +2002,8 @@ STATIC void	S_hv_magic_check(pTHX_ HV *hv, bool *needs_copy, bool *needs_store)
 
 STATIC void	S_unshare_hek_or_pvn(pTHX_ const HEK* hek, const char* str, I32 len, U32 hash);
 STATIC HEK*	S_share_hek_flags(pTHX_ const char* sv, I32 len, U32 hash, int flags)
-			__attribute__warn_unused_result__;
+			__attribute__warn_unused_result__
+			__attribute__nonnull__(pTHX_1);
 
 STATIC void	S_hv_notallowed(pTHX_ int flags, const char *key, I32 klen, const char *msg)
 			__attribute__noreturn__
@@ -2547,14 +2564,32 @@ STATIC SV*	S_save_scalar_at(pTHX_ SV **sptr);
 #endif
 
 #if defined(PERL_IN_SV_C) || defined(PERL_DECL_PROT)
-STATIC IV	S_asIV(pTHX_ SV* sv);
-STATIC UV	S_asUV(pTHX_ SV* sv);
-STATIC void	S_sv_unglob(pTHX_ SV* sv);
-STATIC void	S_not_a_number(pTHX_ SV *sv);
-STATIC I32	S_visit(pTHX_ SVFUNC_t f, U32 flags, U32 mask);
-STATIC void	S_sv_add_backref(pTHX_ SV *tsv, SV *sv);
-STATIC void	S_sv_del_backref(pTHX_ SV *sv);
+STATIC IV	S_asIV(pTHX_ SV* sv)
+			__attribute__warn_unused_result__
+			__attribute__nonnull__(pTHX_1);
+
+STATIC UV	S_asUV(pTHX_ SV* sv)
+			__attribute__warn_unused_result__
+			__attribute__nonnull__(pTHX_1);
+
+STATIC void	S_sv_unglob(pTHX_ SV* sv)
+			__attribute__nonnull__(pTHX_1);
+
+STATIC void	S_not_a_number(pTHX_ SV *sv)
+			__attribute__nonnull__(pTHX_1);
+
+STATIC I32	S_visit(pTHX_ SVFUNC_t f, U32 flags, U32 mask)
+			__attribute__nonnull__(pTHX_1);
+
+STATIC void	S_sv_add_backref(pTHX_ SV *tsv, SV *sv)
+			__attribute__nonnull__(pTHX_1)
+			__attribute__nonnull__(pTHX_2);
+
+STATIC void	S_sv_del_backref(pTHX_ SV *sv)
+			__attribute__nonnull__(pTHX_1);
+
 STATIC SV *	S_varname(pTHX_ GV *gv, const char *gvtype, PADOFFSET targ, SV *keyname, I32 aindex, int subscript_type)
+			__attribute__warn_unused_result__
 			__attribute__nonnull__(pTHX_2);
 
 #  ifdef DEBUGGING
diff --git a/sv.c b/sv.c
index 3888ce09be..13a51f1200 100644
--- a/sv.c
+++ b/sv.c
@@ -512,7 +512,7 @@ Perl_sv_clean_all(pTHX)
 static void 
 S_free_arena(pTHX_ void **root) {
     while (root) {
-	void **next = *(void **)root;
+	void ** const next = *(void **)root;
 	Safefree(root);
 	root = next;
     }
@@ -690,7 +690,7 @@ S_varname(pTHX_ GV *gv, const char *gvtype, PADOFFSET targ,
 	AV *av;
 
 	if (!cv || !CvPADLIST(cv))
-	    return Nullsv;;
+	    return Nullsv;
 	av = (AV*)(*av_fetch(CvPADLIST(cv), 0, FALSE));
 	sv = *av_fetch(av, targ, FALSE);
 	/* SvLEN in a pad name is not to be trusted */
@@ -698,9 +698,8 @@ S_varname(pTHX_ GV *gv, const char *gvtype, PADOFFSET targ,
     }
 
     if (subscript_type == FUV_SUBSCRIPT_HASH) {
-	SV *sv;
+	SV * const sv = NEWSV(0,0);
 	*SvPVX(name) = '$';
-	sv = NEWSV(0,0);
 	Perl_sv_catpvf(aTHX_ name, "{%s}",
 	    pv_display(sv,SvPVX_const(keyname), SvCUR(keyname), 0, 32));
 	SvREFCNT_dec(sv);
@@ -742,7 +741,6 @@ S_find_uninit_var(pTHX_ OP* obase, SV* uninit_sv, bool match)
     dVAR;
     SV *sv;
     AV *av;
-    SV **svp;
     GV *gv;
     OP *o, *o2, *kid;
 
@@ -795,25 +793,26 @@ S_find_uninit_var(pTHX_ OP* obase, SV* uninit_sv, bool match)
 	if (match && subscript_type == FUV_SUBSCRIPT_WITHIN)
 	    break;
 
-	return S_varname(aTHX_ gv, hash ? "%" : "@", obase->op_targ,
+	return varname(gv, hash ? "%" : "@", obase->op_targ,
 				    keysv, index, subscript_type);
       }
 
     case OP_PADSV:
 	if (match && PAD_SVl(obase->op_targ) != uninit_sv)
 	    break;
-	return S_varname(aTHX_ Nullgv, "$", obase->op_targ,
+	return varname(Nullgv, "$", obase->op_targ,
 				    Nullsv, 0, FUV_SUBSCRIPT_NONE);
 
     case OP_GVSV:
 	gv = cGVOPx_gv(obase);
 	if (!gv || (match && GvSV(gv) != uninit_sv))
 	    break;
-	return S_varname(aTHX_ gv, "$", 0, Nullsv, 0, FUV_SUBSCRIPT_NONE);
+	return varname(gv, "$", 0, Nullsv, 0, FUV_SUBSCRIPT_NONE);
 
     case OP_AELEMFAST:
 	if (obase->op_flags & OPf_SPECIAL) { /* lexical array */
 	    if (match) {
+		SV **svp;
 		av = (AV*)PAD_SV(obase->op_targ);
 		if (!av || SvRMAGICAL(av))
 		    break;
@@ -821,7 +820,7 @@ S_find_uninit_var(pTHX_ OP* obase, SV* uninit_sv, bool match)
 		if (!svp || *svp != uninit_sv)
 		    break;
 	    }
-	    return S_varname(aTHX_ Nullgv, "$", obase->op_targ,
+	    return varname(Nullgv, "$", obase->op_targ,
 		    Nullsv, (I32)obase->op_private, FUV_SUBSCRIPT_ARRAY);
 	}
 	else {
@@ -829,6 +828,7 @@ S_find_uninit_var(pTHX_ OP* obase, SV* uninit_sv, bool match)
 	    if (!gv)
 		break;
 	    if (match) {
+		SV **svp;
 		av = GvAV(gv);
 		if (!av || SvRMAGICAL(av))
 		    break;
@@ -836,7 +836,7 @@ S_find_uninit_var(pTHX_ OP* obase, SV* uninit_sv, bool match)
 		if (!svp || *svp != uninit_sv)
 		    break;
 	    }
-	    return S_varname(aTHX_ gv, "$", 0,
+	    return varname(gv, "$", 0,
 		    Nullsv, (I32)obase->op_private, FUV_SUBSCRIPT_ARRAY);
 	}
 	break;
@@ -885,16 +885,16 @@ S_find_uninit_var(pTHX_ OP* obase, SV* uninit_sv, bool match)
 			break;
 		}
 		else {
-		    svp = av_fetch((AV*)sv, SvIV(cSVOPx_sv(kid)), FALSE);
+		    SV ** const svp = av_fetch((AV*)sv, SvIV(cSVOPx_sv(kid)), FALSE);
 		    if (!svp || *svp != uninit_sv)
 			break;
 		}
 	    }
 	    if (obase->op_type == OP_HELEM)
-		return S_varname(aTHX_ gv, "%", o->op_targ,
+		return varname(gv, "%", o->op_targ,
 			    cSVOPx_sv(kid), 0, FUV_SUBSCRIPT_HASH);
 	    else
-		return S_varname(aTHX_ gv, "@", o->op_targ, Nullsv,
+		return varname(gv, "@", o->op_targ, Nullsv,
 			    SvIV(cSVOPx_sv(kid)), FUV_SUBSCRIPT_ARRAY);
 	    ;
 	}
@@ -904,18 +904,18 @@ S_find_uninit_var(pTHX_ OP* obase, SV* uninit_sv, bool match)
 	    if (obase->op_type == OP_HELEM) {
 		SV * const keysv = S_find_hash_subscript(aTHX_ (HV*)sv, uninit_sv);
 		if (keysv)
-		    return S_varname(aTHX_ gv, "%", o->op_targ,
+		    return varname(gv, "%", o->op_targ,
 						keysv, 0, FUV_SUBSCRIPT_HASH);
 	    }
 	    else {
 		const I32 index = S_find_array_subscript(aTHX_ (AV*)sv, uninit_sv);
 		if (index >= 0)
-		    return S_varname(aTHX_ gv, "@", o->op_targ,
+		    return varname(gv, "@", o->op_targ,
 					Nullsv, index, FUV_SUBSCRIPT_ARRAY);
 	    }
 	    if (match)
 		break;
-	    return S_varname(aTHX_ gv,
+	    return varname(gv,
 		(o->op_type == OP_PADAV || o->op_type == OP_RV2AV)
 		? "@" : "%",
 		o->op_targ, Nullsv, 0, FUV_SUBSCRIPT_WITHIN);
@@ -939,7 +939,7 @@ S_find_uninit_var(pTHX_ OP* obase, SV* uninit_sv, bool match)
 		gv = cGVOPx_gv(o);
 		if (match && GvSV(gv) != uninit_sv)
 		    break;
-		return S_varname(aTHX_ gv, "$", 0,
+		return varname(gv, "$", 0,
 			    Nullsv, 0, FUV_SUBSCRIPT_NONE);
 	    }
 	    /* other possibilities not handled are:
@@ -1830,7 +1830,7 @@ S_not_a_number(pTHX_ SV *sv)
 {
      SV *dsv;
      char tmpbuf[64];
-     char *pv;
+     const char *pv;
 
      if (DO_UTF8(sv)) {
           dsv = sv_2mortal(newSVpv("", 0));
@@ -5245,7 +5245,7 @@ S_sv_del_backref(pTHX_ SV *sv)
     AV *av;
     SV **svp;
     I32 i;
-    SV *tsv = SvRV(sv);
+    SV * const tsv = SvRV(sv);
     MAGIC *mg = NULL;
     if (!SvMAGICAL(tsv) || !(mg = mg_find(tsv, PERL_MAGIC_backref)))
 	Perl_croak(aTHX_ "panic: del_backref");
@@ -5472,7 +5472,7 @@ Perl_sv_clear(pTHX_ register SV *sv)
 		stash = SvSTASH(sv);
 		destructor = StashHANDLER(stash,DESTROY);
 		if (destructor) {
-		    SV* tmpref = newRV(sv);
+		    SV* const tmpref = newRV(sv);
 	            SvREADONLY_on(tmpref);   /* DESTROY() could be naughty */
 		    ENTER;
 		    PUSHSTACKi(PERLSI_DESTROY);
@@ -6530,7 +6530,7 @@ Perl_sv_gets(pTHX_ register SV *sv, register PerlIO *fp, I32 append)
 		sv_pos_u2b(sv,&append,0);
 	    }
 	} else if (SvUTF8(sv)) {
-	    SV *tsv = NEWSV(0,0);
+	    SV * const tsv = NEWSV(0,0);
 	    sv_gets(tsv, fp, 0);
 	    sv_utf8_upgrade_nomg(tsv);
 	    SvCUR_set(sv,append);
@@ -8053,7 +8053,7 @@ Perl_sv_reftype(pTHX_ const SV *sv, int ob)
     /* The fact that I don't need to downcast to char * everywhere, only in ?:
        inside return suggests a const propagation bug in g++.  */
     if (ob && SvOBJECT(sv)) {
-	char *name = HvNAME_get(SvSTASH(sv));
+	char * const name = HvNAME_get(SvSTASH(sv));
 	return name ? name : (char *) "__ANON__";
     }
     else {
@@ -8187,7 +8187,7 @@ Perl_newSVrv(pTHX_ SV *rv, const char *classname)
     SvROK_on(rv);
 
     if (classname) {
-	HV* stash = gv_stashpv(classname, TRUE);
+	HV* const stash = gv_stashpv(classname, TRUE);
 	(void)sv_bless(rv, stash);
     }
     return sv;
@@ -8296,7 +8296,7 @@ Note that C<sv_setref_pv> copies the pointer while this copies the string.
 */
 
 SV*
-Perl_sv_setref_pvn(pTHX_ SV *rv, const char *classname, char *pv, STRLEN n)
+Perl_sv_setref_pvn(pTHX_ SV *rv, const char *classname, const char *pv, STRLEN n)
 {
     sv_setpvn(newSVrv(rv,classname), pv, n);
     return rv;
diff --git a/util.c b/util.c
index b5a2d49d5b..d5c074fa74 100644
--- a/util.c
+++ b/util.c
@@ -3340,11 +3340,13 @@ Perl_init_tm(pTHX_ struct tm *ptm)	/* see mktime, strftime and asctime */
 {
 #ifdef HAS_TM_TM_ZONE
     Time_t now;
-    struct tm* my_tm;
+    const struct tm* my_tm;
     (void)time(&now);
     my_tm = localtime(&now);
     if (my_tm)
         Copy(my_tm, ptm, 1, struct tm);
+#else
+    PERL_UNUSED_ARG(ptm);
 #endif
 }