Consting part 4

Message-ID: <20050325204331.GA16388@petdance.com>

p4raw-id: //depot/perl@24079

14 files changed, 87 insertions, 66 deletions

diff --git a/embed.fnc b/embed.fnc
index 4904dc9df3..4faf632410 100644
--- a/embed.fnc
+++ b/embed.fnc
@@ -400,7 +400,7 @@ p	|U32	|magic_len	|SV* sv|MAGIC* mg
 p	|int	|magic_nextpack	|SV* sv|MAGIC* mg|SV* key
 p	|U32	|magic_regdata_cnt|SV* sv|MAGIC* mg
 p	|int	|magic_regdatum_get|SV* sv|MAGIC* mg
-p	|int	|magic_regdatum_set|SV* sv|MAGIC* mg
+pr	|int	|magic_regdatum_set|SV* sv|MAGIC* mg
 p	|int	|magic_set	|SV* sv|MAGIC* mg
 p	|int	|magic_setamagic|SV* sv|MAGIC* mg
 p	|int	|magic_setarylen|SV* sv|MAGIC* mg
@@ -549,7 +549,7 @@ Apd	|int	|vcmp		|SV *lvs|SV *rvs
 p	|PerlIO*|nextargv	|GV* gv
 Ap	|char*	|ninstr		|const char* big|const char* bigend \
 				|const char* little|const char* lend
-p	|OP*	|oopsCV		|OP* o
+pr	|OP*	|oopsCV		|OP* o
 Ap	|void	|op_free	|OP* arg
 p	|void	|package	|OP* o
 pd	|PADOFFSET|pad_alloc	|I32 optype|U32 tmptype
@@ -655,7 +655,7 @@ Ap	|void	|save_shared_pvref|char** str
 Ap	|void	|save_gp	|GV* gv|I32 empty
 Ap	|HV*	|save_hash	|GV* gv
 Ap	|void	|save_helem	|HV* hv|SV *key|SV **sptr
-Ap	|void	|save_hints
+Apr	|void	|save_hints
 Ap	|void	|save_hptr	|HV** hptr
 Ap	|void	|save_I16	|I16* intp
 Ap	|void	|save_I32	|I32* intp
@@ -675,16 +675,16 @@ Ap	|void	|save_re_context
 Ap	|void	|save_padsv	|PADOFFSET off
 Ap	|void	|save_sptr	|SV** sptr
 Ap	|SV*	|save_svref	|SV** sptr
-Ap	|SV**	|save_threadsv	|PADOFFSET i
+Apr	|SV**	|save_threadsv	|PADOFFSET i
 p	|OP*	|sawparens	|OP* o
 p	|OP*	|scalar		|OP* o
 p	|OP*	|scalarkids	|OP* o
 p	|OP*	|scalarseq	|OP* o
 p	|OP*	|scalarvoid	|OP* o
-Apd	|NV	|scan_bin	|char* start|STRLEN len|STRLEN* retlen
-Apd	|NV	|scan_hex	|char* start|STRLEN len|STRLEN* retlen
+Apd	|NV	|scan_bin	|const char* start|STRLEN len|STRLEN* retlen
+Apd	|NV	|scan_hex	|const char* start|STRLEN len|STRLEN* retlen
 Ap	|char*	|scan_num	|const char* s|YYSTYPE *lvalp
-Apd	|NV	|scan_oct	|char* start|STRLEN len|STRLEN* retlen
+Apd	|NV	|scan_oct	|const char* start|STRLEN len|STRLEN* retlen
 p	|OP*	|scope		|OP* o
 Ap	|char*	|screaminstr	|SV* bigsv|SV* littlesv|I32 start_shift \
 				|I32 end_shift|I32 *state|I32 last
@@ -920,7 +920,7 @@ Apd	|SV*	|sv_rvweaken	|SV *sv
 p	|int	|magic_killbackrefs|SV *sv|MAGIC *mg
 Ap	|OP*	|newANONATTRSUB	|I32 floor|OP *proto|OP *attrs|OP *block
 Ap	|CV*	|newATTRSUB	|I32 floor|OP *o|OP *proto|OP *attrs|OP *block
-Ap	|void	|newMYSUB	|I32 floor|OP *o|OP *proto|OP *attrs|OP *block
+Apr	|void	|newMYSUB	|I32 floor|OP *o|OP *proto|OP *attrs|OP *block
 p	|OP *	|my_attrs	|OP *o|OP *attrs
 p	|void	|boot_core_xsutils
 #if defined(USE_ITHREADS)
@@ -989,7 +989,7 @@ s	|HEK*	|save_hek_flags	|const char *str|I32 len|U32 hash|int flags
 s	|void	|hv_magic_check	|HV *hv|bool *needs_copy|bool *needs_store
 s	|void	|unshare_hek_or_pvn|HEK* hek|const char* sv|I32 len|U32 hash
 s	|HEK*	|share_hek_flags|const char* sv|I32 len|U32 hash|int flags
-s	|void	|hv_notallowed	|int flags|const char *key|I32 klen|const char *msg
+rs	|void	|hv_notallowed	|int flags|const char *key|I32 klen|const char *msg
 #endif
 
 #if defined(PERL_IN_MG_C) || defined(PERL_DECL_PROT)
@@ -1130,7 +1130,7 @@ Es	|I32	|study_chunk	|struct RExC_state_t*|regnode **scanp|I32 *deltap \
 				|regnode *last|struct scan_data_t *data \
 				|U32 flags|U32 depth
 Es	|I32	|add_data	|struct RExC_state_t*|I32 n|const char *s
-rs	|void|re_croak2	|const char* pat1|const char* pat2|...
+rs	|void	|re_croak2	|const char* pat1|const char* pat2|...
 Es	|I32	|regpposixcc	|struct RExC_state_t*|I32 value
 Es	|void	|checkposixcc	|struct RExC_state_t*
 
@@ -1259,7 +1259,7 @@ s	|void	|incline	|char *s
 s	|int	|intuit_method	|char *s|GV *gv
 s	|int	|intuit_more	|char *s
 s	|I32	|lop		|I32 f|int x|char *s
-s	|void	|missingterm	|char *s
+rs	|void	|missingterm	|char *s
 s	|void	|no_op		|const char *what|char *s
 s	|void	|set_csh
 s	|I32	|sublex_done
diff --git a/mg.c b/mg.c
index 679c51ea16..db1175fd44 100644
--- a/mg.c
+++ b/mg.c
@@ -476,6 +476,7 @@ Perl_magic_regdatum_set(pTHX_ SV *sv, MAGIC *mg)
 {
     Perl_croak(aTHX_ PL_no_modify);
     /* NOT REACHED */
+    (void)sv; (void)mg;
     return 0;
 }
 
diff --git a/numeric.c b/numeric.c
index a6386e85dd..aeb1a0240f 100644
--- a/numeric.c
+++ b/numeric.c
@@ -471,33 +471,33 @@ For backwards compatibility. Use C<grok_oct> instead.
  */
 
 NV
-Perl_scan_bin(pTHX_ char *start, STRLEN len, STRLEN *retlen)
+Perl_scan_bin(pTHX_ const char *start, STRLEN len, STRLEN *retlen)
 {
     NV rnv;
     I32 flags = *retlen ? PERL_SCAN_ALLOW_UNDERSCORES : 0;
-    UV ruv = grok_bin (start, &len, &flags, &rnv);
+    const UV ruv = grok_bin (start, &len, &flags, &rnv);
 
     *retlen = len;
     return (flags & PERL_SCAN_GREATER_THAN_UV_MAX) ? rnv : (NV)ruv;
 }
 
 NV
-Perl_scan_oct(pTHX_ char *start, STRLEN len, STRLEN *retlen)
+Perl_scan_oct(pTHX_ const char *start, STRLEN len, STRLEN *retlen)
 {
     NV rnv;
     I32 flags = *retlen ? PERL_SCAN_ALLOW_UNDERSCORES : 0;
-    UV ruv = grok_oct (start, &len, &flags, &rnv);
+    const UV ruv = grok_oct (start, &len, &flags, &rnv);
 
     *retlen = len;
     return (flags & PERL_SCAN_GREATER_THAN_UV_MAX) ? rnv : (NV)ruv;
 }
 
 NV
-Perl_scan_hex(pTHX_ char *start, STRLEN len, STRLEN *retlen)
+Perl_scan_hex(pTHX_ const char *start, STRLEN len, STRLEN *retlen)
 {
     NV rnv;
     I32 flags = *retlen ? PERL_SCAN_ALLOW_UNDERSCORES : 0;
-    UV ruv = grok_hex (start, &len, &flags, &rnv);
+    const UV ruv = grok_hex (start, &len, &flags, &rnv);
 
     *retlen = len;
     return (flags & PERL_SCAN_GREATER_THAN_UV_MAX) ? rnv : (NV)ruv;
@@ -516,7 +516,7 @@ Perl_grok_numeric_radix(pTHX_ const char **sp, const char *send)
 #ifdef USE_LOCALE_NUMERIC
     if (PL_numeric_radix_sv && IN_LOCALE) { 
         STRLEN len;
-        char* radix = SvPV(PL_numeric_radix_sv, len);
+        const char* radix = SvPV(PL_numeric_radix_sv, len);
         if (*sp + len <= send && memEQ(*sp, radix, len)) {
             *sp += len;
             return TRUE; 
@@ -998,7 +998,7 @@ Perl_my_atof2(pTHX_ const char* orig, NV* value)
 	result[2] = -result[2];
 #endif /* USE_PERL_ATOF */
     *value = result[2];
-    return s;
+    return (char *)s;
 }
 
 #if ! defined(HAS_MODFL) && defined(HAS_AINTL) && defined(HAS_COPYSIGNL)
diff --git a/op.c b/op.c
index 9fa2176216..a1542f3520 100644
--- a/op.c
+++ b/op.c
@@ -1851,7 +1851,7 @@ Perl_save_hints(pTHX)
 int
 Perl_block_start(pTHX_ int full)
 {
-    int retval = PL_savestack_ix;
+    const int retval = PL_savestack_ix;
     pad_block_start(full);
     SAVEHINTS();
     PL_hints &= ~HINT_BLOCK_SCOPE;
@@ -3699,8 +3699,9 @@ Perl_newLOOPOP(pTHX_ I32 flags, I32 debuggable, OP *expr, OP *block)
 {
     OP* listop;
     OP* o;
-    int once = block && block->op_flags & OPf_SPECIAL &&
+    const bool once = block && block->op_flags & OPf_SPECIAL &&
       (block->op_type == OP_ENTERSUB || block->op_type == OP_NULL);
+    (void)debuggable;
 
     if (expr) {
 	if (once && expr->op_type == OP_CONST && !SvTRUE(((SVOP*)expr)->op_sv))
@@ -3710,8 +3711,8 @@ Perl_newLOOPOP(pTHX_ I32 flags, I32 debuggable, OP *expr, OP *block)
 	    expr = newUNOP(OP_DEFINED, 0,
 		newASSIGNOP(0, newDEFSVOP(), 0, expr) );
 	} else if (expr->op_flags & OPf_KIDS) {
-	    OP *k1 = ((UNOP*)expr)->op_first;
-	    OP *k2 = (k1) ? k1->op_sibling : NULL;
+            const OP *k1 = ((UNOP*)expr)->op_first;
+            const OP *k2 = (k1) ? k1->op_sibling : NULL;
 	    switch (expr->op_type) {
 	      case OP_NULL:
 		if (k2 && k2->op_type == OP_READLINE
@@ -3761,6 +3762,7 @@ Perl_newWHILEOP(pTHX_ I32 flags, I32 debuggable, LOOP *loop, I32 whileline, OP *
     OP *listop;
     OP *o;
     U8 loopflags = 0;
+    (void)debuggable;
 
     if (expr && (expr->op_type == OP_READLINE || expr->op_type == OP_GLOB
 		 || (expr->op_type == OP_NULL && expr->op_targ == OP_GLOB))) {
@@ -3879,7 +3881,7 @@ Perl_newFOROP(pTHX_ I32 flags,char *label,line_t forline,OP *sv,OP *expr,OP *blo
 	    Perl_croak(aTHX_ "Can't use %s for loop variable", PL_op_desc[sv->op_type]);
     }
     else {
-	I32 offset = pad_findmy("$_");
+        const I32 offset = pad_findmy("$_");
 	if (offset == NOT_IN_PAD || PAD_COMPNAME_FLAGS(offset) & SVpad_OUR) {
 	    sv = newGVOP(OP_GV, 0, PL_defgv);
 	}
@@ -4158,6 +4160,7 @@ Perl_op_const_sv(pTHX_ OP *o, CV *cv)
 void
 Perl_newMYSUB(pTHX_ I32 floor, OP *o, OP *proto, OP *attrs, OP *block)
 {
+    (void)floor;
     if (o)
 	SAVEFREEOP(o);
     if (proto)
@@ -4842,7 +4845,7 @@ Perl_oopsCV(pTHX_ OP *o)
 {
     Perl_croak(aTHX_ "NOT IMPL LINE %d",__LINE__);
     /* STUB */
-    return o;
+    (void)o;
 }
 
 OP *
diff --git a/perlio.c b/perlio.c
index 2f5373c20f..4d2b6a93f0 100644
--- a/perlio.c
+++ b/perlio.c
@@ -4727,8 +4727,8 @@ char *
 PerlIO_getname(PerlIO *f, char *buf)
 {
     dTHX;
-    char *name = NULL;
 #ifdef VMS
+    char *name = NULL;
     bool exported = FALSE;
     FILE *stdio = PerlIOSelf(f, PerlIOStdio)->stdio;
     if (!stdio) {
@@ -4739,10 +4739,12 @@ PerlIO_getname(PerlIO *f, char *buf)
 	name = fgetname(stdio, buf);
 	if (exported) PerlIO_releaseFILE(f,stdio);
     }
+    return name;
 #else
+    (void)f;
+    (void)buf;
     Perl_croak(aTHX_ "Don't know how to get file name");
 #endif
-    return name;
 }
 
 
diff --git a/pod/perlapi.pod b/pod/perlapi.pod
index a915892a01..a724f3eb4d 100644
--- a/pod/perlapi.pod
+++ b/pod/perlapi.pod
@@ -2139,7 +2139,7 @@ Found in file numeric.c
 
 For backwards compatibility. Use C<grok_bin> instead.
 
-	NV	scan_bin(char* start, STRLEN len, STRLEN* retlen)
+	NV	scan_bin(const char* start, STRLEN len, STRLEN* retlen)
 
 =for hackers
 Found in file numeric.c
@@ -2148,7 +2148,7 @@ Found in file numeric.c
 
 For backwards compatibility. Use C<grok_hex> instead.
 
-	NV	scan_hex(char* start, STRLEN len, STRLEN* retlen)
+	NV	scan_hex(const char* start, STRLEN len, STRLEN* retlen)
 
 =for hackers
 Found in file numeric.c
@@ -2157,7 +2157,7 @@ Found in file numeric.c
 
 For backwards compatibility. Use C<grok_oct> instead.
 
-	NV	scan_oct(char* start, STRLEN len, STRLEN* retlen)
+	NV	scan_oct(const char* start, STRLEN len, STRLEN* retlen)
 
 =for hackers
 Found in file numeric.c
@@ -5097,6 +5097,8 @@ missing (NULL).  When running with taint checks enabled, indicates via
 C<maybe_tainted> if results are untrustworthy (often due to the use of
 locales).
 
+XXX Except that it maybe_tainted is never assigned to.
+
 Usually used via one of its frontends C<sv_vcatpvf> and C<sv_vcatpvf_mg>.
 
 	void	sv_vcatpvfn(SV* sv, const char* pat, STRLEN patlen, va_list* args, SV** svargs, I32 svmax, bool *maybe_tainted)
diff --git a/proto.h b/proto.h
index a40c23ec36..6a7564f95a 100644
--- a/proto.h
+++ b/proto.h
@@ -377,7 +377,7 @@ PERL_CALLCONV U32	Perl_magic_len(pTHX_ SV* sv, MAGIC* mg);
 PERL_CALLCONV int	Perl_magic_nextpack(pTHX_ SV* sv, MAGIC* mg, SV* key);
 PERL_CALLCONV U32	Perl_magic_regdata_cnt(pTHX_ SV* sv, MAGIC* mg);
 PERL_CALLCONV int	Perl_magic_regdatum_get(pTHX_ SV* sv, MAGIC* mg);
-PERL_CALLCONV int	Perl_magic_regdatum_set(pTHX_ SV* sv, MAGIC* mg);
+PERL_CALLCONV int	Perl_magic_regdatum_set(pTHX_ SV* sv, MAGIC* mg) __attribute__((noreturn));
 PERL_CALLCONV int	Perl_magic_set(pTHX_ SV* sv, MAGIC* mg);
 PERL_CALLCONV int	Perl_magic_setamagic(pTHX_ SV* sv, MAGIC* mg);
 PERL_CALLCONV int	Perl_magic_setarylen(pTHX_ SV* sv, MAGIC* mg);
@@ -525,7 +525,7 @@ PERL_CALLCONV SV*	Perl_vstringify(pTHX_ SV *vs);
 PERL_CALLCONV int	Perl_vcmp(pTHX_ SV *lvs, SV *rvs);
 PERL_CALLCONV PerlIO*	Perl_nextargv(pTHX_ GV* gv);
 PERL_CALLCONV char*	Perl_ninstr(pTHX_ const char* big, const char* bigend, const char* little, const char* lend);
-PERL_CALLCONV OP*	Perl_oopsCV(pTHX_ OP* o);
+PERL_CALLCONV OP*	Perl_oopsCV(pTHX_ OP* o) __attribute__((noreturn));
 PERL_CALLCONV void	Perl_op_free(pTHX_ OP* arg);
 PERL_CALLCONV void	Perl_package(pTHX_ OP* o);
 PERL_CALLCONV PADOFFSET	Perl_pad_alloc(pTHX_ I32 optype, U32 tmptype);
@@ -624,7 +624,7 @@ PERL_CALLCONV void	Perl_save_shared_pvref(pTHX_ char** str);
 PERL_CALLCONV void	Perl_save_gp(pTHX_ GV* gv, I32 empty);
 PERL_CALLCONV HV*	Perl_save_hash(pTHX_ GV* gv);
 PERL_CALLCONV void	Perl_save_helem(pTHX_ HV* hv, SV *key, SV **sptr);
-PERL_CALLCONV void	Perl_save_hints(pTHX);
+PERL_CALLCONV void	Perl_save_hints(pTHX) __attribute__((noreturn));
 PERL_CALLCONV void	Perl_save_hptr(pTHX_ HV** hptr);
 PERL_CALLCONV void	Perl_save_I16(pTHX_ I16* intp);
 PERL_CALLCONV void	Perl_save_I32(pTHX_ I32* intp);
@@ -644,16 +644,16 @@ PERL_CALLCONV void	Perl_save_re_context(pTHX);
 PERL_CALLCONV void	Perl_save_padsv(pTHX_ PADOFFSET off);
 PERL_CALLCONV void	Perl_save_sptr(pTHX_ SV** sptr);
 PERL_CALLCONV SV*	Perl_save_svref(pTHX_ SV** sptr);
-PERL_CALLCONV SV**	Perl_save_threadsv(pTHX_ PADOFFSET i);
+PERL_CALLCONV SV**	Perl_save_threadsv(pTHX_ PADOFFSET i) __attribute__((noreturn));
 PERL_CALLCONV OP*	Perl_sawparens(pTHX_ OP* o);
 PERL_CALLCONV OP*	Perl_scalar(pTHX_ OP* o);
 PERL_CALLCONV OP*	Perl_scalarkids(pTHX_ OP* o);
 PERL_CALLCONV OP*	Perl_scalarseq(pTHX_ OP* o);
 PERL_CALLCONV OP*	Perl_scalarvoid(pTHX_ OP* o);
-PERL_CALLCONV NV	Perl_scan_bin(pTHX_ char* start, STRLEN len, STRLEN* retlen);
-PERL_CALLCONV NV	Perl_scan_hex(pTHX_ char* start, STRLEN len, STRLEN* retlen);
+PERL_CALLCONV NV	Perl_scan_bin(pTHX_ const char* start, STRLEN len, STRLEN* retlen);
+PERL_CALLCONV NV	Perl_scan_hex(pTHX_ const char* start, STRLEN len, STRLEN* retlen);
 PERL_CALLCONV char*	Perl_scan_num(pTHX_ const char* s, YYSTYPE *lvalp);
-PERL_CALLCONV NV	Perl_scan_oct(pTHX_ char* start, STRLEN len, STRLEN* retlen);
+PERL_CALLCONV NV	Perl_scan_oct(pTHX_ const char* start, STRLEN len, STRLEN* retlen);
 PERL_CALLCONV OP*	Perl_scope(pTHX_ OP* o);
 PERL_CALLCONV char*	Perl_screaminstr(pTHX_ SV* bigsv, SV* littlesv, I32 start_shift, I32 end_shift, I32 *state, I32 last);
 #if !defined(VMS)
@@ -881,7 +881,7 @@ PERL_CALLCONV SV*	Perl_sv_rvweaken(pTHX_ SV *sv);
 PERL_CALLCONV int	Perl_magic_killbackrefs(pTHX_ SV *sv, MAGIC *mg);
 PERL_CALLCONV OP*	Perl_newANONATTRSUB(pTHX_ I32 floor, OP *proto, OP *attrs, OP *block);
 PERL_CALLCONV CV*	Perl_newATTRSUB(pTHX_ I32 floor, OP *o, OP *proto, OP *attrs, OP *block);
-PERL_CALLCONV void	Perl_newMYSUB(pTHX_ I32 floor, OP *o, OP *proto, OP *attrs, OP *block);
+PERL_CALLCONV void	Perl_newMYSUB(pTHX_ I32 floor, OP *o, OP *proto, OP *attrs, OP *block) __attribute__((noreturn));
 PERL_CALLCONV OP *	Perl_my_attrs(pTHX_ OP *o, OP *attrs);
 PERL_CALLCONV void	Perl_boot_core_xsutils(pTHX);
 #if defined(USE_ITHREADS)
@@ -949,7 +949,7 @@ STATIC HEK*	S_save_hek_flags(pTHX_ const char *str, I32 len, U32 hash, int flags
 STATIC void	S_hv_magic_check(pTHX_ HV *hv, bool *needs_copy, bool *needs_store);
 STATIC void	S_unshare_hek_or_pvn(pTHX_ HEK* hek, const char* sv, I32 len, U32 hash);
 STATIC HEK*	S_share_hek_flags(pTHX_ const char* sv, I32 len, U32 hash, int flags);
-STATIC void	S_hv_notallowed(pTHX_ int flags, const char *key, I32 klen, const char *msg);
+STATIC void	S_hv_notallowed(pTHX_ int flags, const char *key, I32 klen, const char *msg) __attribute__((noreturn));
 #endif
 
 #if defined(PERL_IN_MG_C) || defined(PERL_DECL_PROT)
@@ -1207,7 +1207,7 @@ STATIC void	S_incline(pTHX_ char *s);
 STATIC int	S_intuit_method(pTHX_ char *s, GV *gv);
 STATIC int	S_intuit_more(pTHX_ char *s);
 STATIC I32	S_lop(pTHX_ I32 f, int x, char *s);
-STATIC void	S_missingterm(pTHX_ char *s);
+STATIC void	S_missingterm(pTHX_ char *s) __attribute__((noreturn));
 STATIC void	S_no_op(pTHX_ const char *what, char *s);
 STATIC void	S_set_csh(pTHX);
 STATIC I32	S_sublex_done(pTHX);
diff --git a/regcomp.c b/regcomp.c
index 713669cade..4a25d0cb2b 100644
--- a/regcomp.c
+++ b/regcomp.c
@@ -6267,7 +6267,7 @@ S_re_croak2(pTHX_ const char* pat1,const char* pat2,...)
     STRLEN l2 = strlen(pat2);
     char buf[512];
     SV *msv;
-    char *message;
+    const char *message;
 
     if (l1 > 510)
 	l1 = 510;
diff --git a/scope.c b/scope.c
index 56ea96fb12..9bb89b7ac1 100644
--- a/scope.c
+++ b/scope.c
@@ -466,6 +466,7 @@ SV **
 Perl_save_threadsv(pTHX_ PADOFFSET i)
 {
     Perl_croak(aTHX_ "panic: save_threadsv called in non-threaded perl");
+    (void)i;
     return 0;
 }
 
diff --git a/sv.c b/sv.c
index 8d8b44663f..4f0fa987a7 100644
--- a/sv.c
+++ b/sv.c
@@ -3458,7 +3458,7 @@ Perl_sv_2pv_flags(pTHX_ register SV *sv, STRLEN *lp, I32 flags)
 
     if (!sv) {
 	*lp = 0;
-	return "";
+	return (char *)"";
     }
     if (SvGMAGICAL(sv)) {
 	if (flags & SV_GMAGIC)
@@ -3486,7 +3486,7 @@ Perl_sv_2pv_flags(pTHX_ register SV *sv, STRLEN *lp, I32 flags)
 		    report_uninit(sv);
 	    }
             *lp = 0;
-            return "";
+            return (char *)"";
         }
     }
     if (SvTHINKFIRST(sv)) {
@@ -3626,13 +3626,13 @@ Perl_sv_2pv_flags(pTHX_ register SV *sv, STRLEN *lp, I32 flags)
 		goto tokensaveref;
 	    }
 	    *lp = strlen(typestr);
-	    return typestr;
+	    return (char *)typestr;
 	}
 	if (SvREADONLY(sv) && !SvOK(sv)) {
 	    if (ckWARN(WARN_UNINITIALIZED))
 		report_uninit(sv);
 	    *lp = 0;
-	    return "";
+	    return (char *)"";
 	}
     }
     if (SvIOK(sv) || ((SvIOKp(sv) && !SvNOKp(sv)))) {
@@ -3695,7 +3695,7 @@ Perl_sv_2pv_flags(pTHX_ register SV *sv, STRLEN *lp, I32 flags)
 	if (SvTYPE(sv) < SVt_PV)
 	    /* Typically the caller expects that sv_any is not NULL now.  */
 	    sv_upgrade(sv, SVt_PV);
-	return "";
+	return (char *)"";
     }
     *lp = s - SvPVX(sv);
     SvCUR_set(sv, *lp);
@@ -3717,7 +3717,7 @@ Perl_sv_2pv_flags(pTHX_ register SV *sv, STRLEN *lp, I32 flags)
     }
     else {
 	STRLEN len;
-	char *t;
+        const char *t;
 
 	if (tsv) {
 	    sv_2mortal(tsv);
@@ -9141,6 +9141,8 @@ missing (NULL).  When running with taint checks enabled, indicates via
 C<maybe_tainted> if results are untrustworthy (often due to the use of
 locales).
 
+XXX Except that it maybe_tainted is never assigned to.
+
 Usually used via one of its frontends C<sv_vcatpvf> and C<sv_vcatpvf_mg>.
 
 =cut
@@ -9178,7 +9180,7 @@ Perl_sv_vcatpvfn(pTHX_ SV *sv, const char *pat, STRLEN patlen, va_list *args, SV
 	switch (pat[1]) {
 	case 's':
 	    if (args) {
-		char *s = va_arg(*args, char*);
+                const char *s = va_arg(*args, char*);
 		sv_catpv(sv, s ? s : nullstr);
 	    }
 	    else if (svix < svmax) {
@@ -10308,6 +10310,8 @@ PerlIO *
 Perl_fp_dup(pTHX_ PerlIO *fp, char type, CLONE_PARAMS *param)
 {
     PerlIO *ret;
+    (void)type;
+
     if (!fp)
 	return (PerlIO*)NULL;
 
diff --git a/taint.c b/taint.c
index c2865facb9..f21aedcdb4 100644
--- a/taint.c
+++ b/taint.c
@@ -91,7 +91,7 @@ Perl_taint_env(pTHX)
     if (!GvHV(PL_envgv) || !(SvRMAGICAL(GvHV(PL_envgv))
 	    && mg_find((SV*)GvHV(PL_envgv), PERL_MAGIC_env))) {
 	const bool was_tainted = PL_tainted;
-	char *name = GvENAME(PL_envgv);
+        const char *name = GvENAME(PL_envgv);
 	PL_tainted = TRUE;
 	if (strEQ(name,"ENV"))
 	    /* hash alias */
@@ -144,7 +144,7 @@ Perl_taint_env(pTHX)
     svp = hv_fetch(GvHVn(PL_envgv),"TERM",4,FALSE);
     if (svp && *svp && SvTAINTED(*svp)) {
 	STRLEN n_a;
-	bool was_tainted = PL_tainted;
+	const bool was_tainted = PL_tainted;
 	char *t = SvPV(*svp, n_a);
 	char *e = t + n_a;
 	PL_tainted = was_tainted;
diff --git a/toke.c b/toke.c
index c2c7ba22c6..7bbe2bd8c0 100644
--- a/toke.c
+++ b/toke.c
@@ -9419,6 +9419,8 @@ S_scan_heredoc(pTHX_ register char *s)
     I32 len;
     SV *tmpstr;
     char term;
+    const char newline[] = "\n";
+    const char *found_newline;
     register char *d;
     register char *e;
     char *peek;
@@ -9479,11 +9481,13 @@ S_scan_heredoc(pTHX_ register char *s)
 	s = olds;
     }
 #endif
-    d = "\n";
-    if (outer || !(d=ninstr(s,PL_bufend,d,d+1)))
-	herewas = newSVpvn(s,PL_bufend-s);
-    else
-	s--, herewas = newSVpvn(s,d-s);
+    if ( outer || !(found_newline = ninstr(s,PL_bufend,newline,newline+1)) ) {
+        herewas = newSVpvn(s,PL_bufend-s);
+    }
+    else {
+        s--;
+        herewas = newSVpvn(s,found_newline-s);
+    }
     s += SvCUR(herewas);
 
     tmpstr = NEWSV(87,79);
@@ -10489,7 +10493,7 @@ vstring:
     else
 	lvalp->opval = Nullop;
 
-    return s;
+    return (char *)s;
 }
 
 STATIC char *
@@ -10915,7 +10919,7 @@ Perl_scan_vstring(pTHX_ const char *s, SV *sv)
 	if ((PL_bufend - next) >= 2 && *next == '=' && next[1] == '>' ) {
 	    /* return string not v-string */
 	    sv_setpvn(sv,(char *)s,pos-s);
-	    return pos;
+	    return (char *)pos;
 	}
     }
 
@@ -10968,6 +10972,6 @@ Perl_scan_vstring(pTHX_ const char *s, SV *sv)
 	sv_magic(sv,NULL,PERL_MAGIC_vstring,(const char*)start, pos-start);
 	SvRMAGICAL_on(sv);
     }
-    return s;
+    return (char *)s;
 }
 
diff --git a/utf8.c b/utf8.c
index bb31862be9..6fc068040b 100644
--- a/utf8.c
+++ b/utf8.c
@@ -787,7 +787,7 @@ Perl_bytes_from_utf8(pTHX_ const U8 *s, STRLEN *len, bool *is_utf8)
     I32 count = 0;
 
     if (!*is_utf8)
-	return start;
+        return (U8 *)start;
 
     /* ensure valid UTF-8 and chars < 256 before converting string */
     for (send = s + *len; s < send;) {
@@ -797,7 +797,7 @@ Perl_bytes_from_utf8(pTHX_ const U8 *s, STRLEN *len, bool *is_utf8)
                 (c = *s++) && UTF8_IS_CONTINUATION(c))
 		count++;
 	    else
-		return start;
+                return (U8 *)start;
 	}
     }
 
@@ -816,7 +816,7 @@ Perl_bytes_from_utf8(pTHX_ const U8 *s, STRLEN *len, bool *is_utf8)
     }
     *d = '\0';
     *len = d - start;
-    return start;
+    return (U8 *)start;
 }
 
 /*
@@ -1620,7 +1620,7 @@ Perl_swash_init(pTHX_ const char* pkg, const char* name, SV *listsv, I32 minbits
     POPSTACK;
     if (IN_PERL_COMPILETIME) {
 	STRLEN len;
-	char* pv = SvPV(tokenbufsv, len);
+        const char* pv = SvPV(tokenbufsv, len);
 
 	Copy(pv, PL_tokenbuf, len+1, char);
 	PL_curcop->op_private = (U8)(PL_hints & HINT_PRIVATE_MASK);
diff --git a/util.c b/util.c
index ca781771a3..afbe19e644 100644
--- a/util.c
+++ b/util.c
@@ -246,7 +246,7 @@ Perl_delimcpy(pTHX_ register char *to, register const char *toend, register cons
     if (to < toend)
 	*to = '\0';
     *retlen = tolen;
-    return from;
+    return (char *)from;
 }
 
 /* return ptr to little string in big string, NULL if not found */
@@ -1142,7 +1142,7 @@ S_vdie_common(pTHX_ const char *message, STRLEN msglen, I32 utf8)
 OP *
 Perl_vdie(pTHX_ const char* pat, va_list *args)
 {
-    char *message;
+    const char *message;
     const int was_in_eval = PL_in_eval;
     STRLEN msglen;
     I32 utf8 = 0;
@@ -1191,7 +1191,7 @@ Perl_die(pTHX_ const char* pat, ...)
 void
 Perl_vcroak(pTHX_ const char* pat, va_list *args)
 {
-    char *message;
+    const char *message;
     STRLEN msglen;
     I32 utf8 = 0;
 
@@ -2758,6 +2758,7 @@ Perl_find_script(pTHX_ const char *scriptname, bool dosearch, const char **searc
     int extidx = 0, i = 0;
     const char *curext = Nullch;
 #else
+    (void)search_ext;
 #  define MAX_EXT_LEN 0
 #endif
 
@@ -3918,7 +3919,7 @@ Perl_scan_version(pTHX_ const char *s, SV *rv, bool qv)
 	while (len-- > 0)
 	    av_push((AV *)sv, newSViv(0));
     }
-    return s;
+    return (char *)s;
 }
 
 /*
@@ -4465,6 +4466,7 @@ some level of strict-ness.
 void
 Perl_sv_nosharing(pTHX_ SV *sv)
 {
+    (void)sv;
 }
 
 /*
@@ -4480,6 +4482,7 @@ some level of strict-ness.
 void
 Perl_sv_nolocking(pTHX_ SV *sv)
 {
+    (void)sv;
 }
 
 
@@ -4496,6 +4499,7 @@ some level of strict-ness.
 void
 Perl_sv_nounlocking(pTHX_ SV *sv)
 {
+    (void)sv;
 }
 
 U32