Allow lvalue usage of SvRV() and add MUTABLE_SV() check.

Also add new SvRV_const() macro for read-only access.

p4raw-id: //depot/perl@34804

2 files changed, 15 insertions, 3 deletions

diff --git a/sv.c b/sv.c
index 436f18fe44..bae7604f66 100644
--- a/sv.c
+++ b/sv.c
@@ -10562,8 +10562,8 @@ Perl_rvpv_dup(pTHX_ SV *const dstr, const SV *const sstr, CLONE_PARAMS *const pa
 
     if (SvROK(sstr)) {
 	SvRV_set(dstr, SvWEAKREF(sstr)
-		       ? sv_dup(SvRV(sstr), param)
-		       : sv_dup_inc(SvRV(sstr), param));
+		       ? sv_dup(SvRV_const(sstr), param)
+		       : sv_dup_inc(SvRV_const(sstr), param));
 
     }
     else if (SvPVX_const(sstr)) {
diff --git a/sv.h b/sv.h
index 3717070445..7a65fe83d9 100644
--- a/sv.h
+++ b/sv.h
@@ -1048,6 +1048,7 @@ the scalar's value cannot change unless written to.
 #  define SvUVX(sv) (0 + ((XPVUV*) SvANY(sv))->xuv_uv)
 #  define SvNVX(sv) (-0.0 + ((XPVNV*) SvANY(sv))->xnv_u.xnv_nv)
 #  define SvRV(sv) (0 + (sv)->sv_u.svu_rv)
+#  define SvRV_const(sv) (0 + (sv)->sv_u.svu_rv)
 /* Don't test the core XS code yet.  */
 #  if defined (PERL_CORE) && PERL_DEBUG_COW > 1
 #    define SvPVX(sv) (0 + (assert(!SvREADONLY(sv)), (sv)->sv_u.svu_pv))
@@ -1119,7 +1120,7 @@ the scalar's value cannot change unless written to.
 	    &(((XPVNV*) MUTABLE_PTR(SvANY(_svnvx)))->xnv_u.xnv_nv);	\
 	 }))
 #    define SvRV(sv)							\
-	(*({ const SV *const _svrv = (const SV *)(sv);			\
+	(*({ SV *const _svrv = MUTABLE_SV(sv);				\
 	    assert(SvTYPE(_svrv) >= SVt_PV || SvTYPE(_svrv) == SVt_IV);	\
 	    assert(SvTYPE(_svrv) != SVt_PVAV);				\
 	    assert(SvTYPE(_svrv) != SVt_PVHV);				\
@@ -1128,6 +1129,16 @@ the scalar's value cannot change unless written to.
 	    assert(!isGV_with_GP(_svrv));				\
 	    &((_svrv)->sv_u.svu_rv);					\
 	 }))
+#    define SvRV_const(sv)						\
+	({ const SV *const _svrv = (const SV *)(sv);			\
+	    assert(SvTYPE(_svrv) >= SVt_PV || SvTYPE(_svrv) == SVt_IV);	\
+	    assert(SvTYPE(_svrv) != SVt_PVAV);				\
+	    assert(SvTYPE(_svrv) != SVt_PVHV);				\
+	    assert(SvTYPE(_svrv) != SVt_PVCV);				\
+	    assert(SvTYPE(_svrv) != SVt_PVFM);				\
+	    assert(!isGV_with_GP(_svrv));				\
+	    (_svrv)->sv_u.svu_rv;					\
+	 })
 #    define SvMAGIC(sv)							\
 	(*({ const SV *const _svmagic = (const SV *)(sv);		\
 	    assert(SvTYPE(_svmagic) >= SVt_PVMG);			\
@@ -1147,6 +1158,7 @@ the scalar's value cannot change unless written to.
 #    define SvUVX(sv) ((XPVUV*) SvANY(sv))->xuv_uv
 #    define SvNVX(sv) ((XPVNV*) SvANY(sv))->xnv_u.xnv_nv
 #    define SvRV(sv) ((sv)->sv_u.svu_rv)
+#    define SvRV_const(sv) (0 + (sv)->sv_u.svu_rv)
 #    define SvMAGIC(sv)	((XPVMG*)  SvANY(sv))->xmg_u.xmg_magic
 #    define SvSTASH(sv)	((XPVMG*)  SvANY(sv))->xmg_stash
 #  endif