+
+}
+
+/* ---------------------------------------------------------------------
+ *
+ * support functions for report_uninit()
+ */
+
+/* the maxiumum size of array or hash where we will scan looking
+ * for the undefined element that triggered the warning */
+
+#define FUV_MAX_SEARCH_SIZE 1000
+
+/* Look for an entry in the hash whose value has the same SV as val;
+ * If so, return a mortal copy of the key. */
+
+STATIC SV*
+S_find_hash_subscript(pTHX_ HV *hv, SV* val)
+{
+ dVAR;
+ register HE **array;
+ I32 i;
+
+ if (!hv || SvMAGICAL(hv) || !HvARRAY(hv) ||
+ (HvTOTALKEYS(hv) > FUV_MAX_SEARCH_SIZE))
+ return Nullsv;
+
+ array = HvARRAY(hv);
+
+ for (i=HvMAX(hv); i>0; i--) {
+ register HE *entry;
+ for (entry = array[i]; entry; entry = HeNEXT(entry)) {
+ if (HeVAL(entry) != val)
+ continue;
+ if ( HeVAL(entry) == &PL_sv_undef ||
+ HeVAL(entry) == &PL_sv_placeholder)
+ continue;
+ if (!HeKEY(entry))
+ return Nullsv;
+ if (HeKLEN(entry) == HEf_SVKEY)
+ return sv_mortalcopy(HeKEY_sv(entry));
+ return sv_2mortal(newSVpvn(HeKEY(entry), HeKLEN(entry)));
+ }
+ }
+ return Nullsv;
+}
+
+/* Look for an entry in the array whose value has the same SV as val;
+ * If so, return the index, otherwise return -1. */
+
+STATIC I32
+S_find_array_subscript(pTHX_ AV *av, SV* val)
+{
+ SV** svp;
+ I32 i;
+ if (!av || SvMAGICAL(av) || !AvARRAY(av) ||
+ (AvFILLp(av) > FUV_MAX_SEARCH_SIZE))
+ return -1;
+
+ svp = AvARRAY(av);
+ for (i=AvFILLp(av); i>=0; i--) {
+ if (svp[i] == val && svp[i] != &PL_sv_undef)
+ return i;
+ }
+ return -1;
+}
+
+/* S_varname(): return the name of a variable, optionally with a subscript.
+ * If gv is non-zero, use the name of that global, along with gvtype (one
+ * of "$", "@", "%"); otherwise use the name of the lexical at pad offset
+ * targ. Depending on the value of the subscript_type flag, return:
+ */
+
+#define FUV_SUBSCRIPT_NONE 1 /* "@foo" */
+#define FUV_SUBSCRIPT_ARRAY 2 /* "$foo[aindex]" */
+#define FUV_SUBSCRIPT_HASH 3 /* "$foo{keyname}" */
+#define FUV_SUBSCRIPT_WITHIN 4 /* "within @foo" */
+
+STATIC SV*
+S_varname(pTHX_ GV *gv, const char gvtype, PADOFFSET targ,
+ SV* keyname, I32 aindex, int subscript_type)
+{
+
+ SV * const name = sv_newmortal();
+ if (gv) {
+ char buffer[2];
+ buffer[0] = gvtype;
+ buffer[1] = 0;
+
+ /* as gv_fullname4(), but add literal '^' for $^FOO names */
+
+ gv_fullname4(name, gv, buffer, 0);
+
+ if ((unsigned int)SvPVX(name)[1] <= 26) {
+ buffer[0] = '^';
+ buffer[1] = SvPVX(name)[1] + 'A' - 1;
+
+ /* Swap the 1 unprintable control character for the 2 byte pretty
+ version - ie substr($name, 1, 1) = $buffer; */
+ sv_insert(name, 1, 1, buffer, 2);
+ }
+ }
+ else {
+ U32 unused;
+ CV * const cv = find_runcv(&unused);
+ SV *sv;
+ AV *av;
+
+ if (!cv || !CvPADLIST(cv))
+ return Nullsv;
+ av = (AV*)(*av_fetch(CvPADLIST(cv), 0, FALSE));
+ sv = *av_fetch(av, targ, FALSE);
+ /* SvLEN in a pad name is not to be trusted */
+ sv_setpv(name, SvPV_nolen_const(sv));
+ }
+
+ if (subscript_type == FUV_SUBSCRIPT_HASH) {
+ SV * const sv = NEWSV(0,0);
+ *SvPVX(name) = '$';
+ Perl_sv_catpvf(aTHX_ name, "{%s}",
+ pv_display(sv,SvPVX_const(keyname), SvCUR(keyname), 0, 32));
+ SvREFCNT_dec(sv);
+ }
+ else if (subscript_type == FUV_SUBSCRIPT_ARRAY) {
+ *SvPVX(name) = '$';
+ Perl_sv_catpvf(aTHX_ name, "[%"IVdf"]", (IV)aindex);
+ }
+ else if (subscript_type == FUV_SUBSCRIPT_WITHIN)
+ sv_insert(name, 0, 0, "within ", 7);
+
+ return name;
+}
+
+
+/*
+=for apidoc find_uninit_var
+
+Find the name of the undefined variable (if any) that caused the operator o
+to issue a "Use of uninitialized value" warning.
+If match is true, only return a name if it's value matches uninit_sv.
+So roughly speaking, if a unary operator (such as OP_COS) generates a
+warning, then following the direct child of the op may yield an
+OP_PADSV or OP_GV that gives the name of the undefined variable. On the
+other hand, with OP_ADD there are two branches to follow, so we only print
+the variable name if we get an exact match.
+
+The name is returned as a mortal SV.
+
+Assumes that PL_op is the op that originally triggered the error, and that
+PL_comppad/PL_curpad points to the currently executing pad.
+
+=cut
+*/
+
+STATIC SV *
+S_find_uninit_var(pTHX_ OP* obase, SV* uninit_sv, bool match)
+{
+ dVAR;
+ SV *sv;
+ AV *av;
+ GV *gv;
+ OP *o, *o2, *kid;
+
+ if (!obase || (match && (!uninit_sv || uninit_sv == &PL_sv_undef ||
+ uninit_sv == &PL_sv_placeholder)))
+ return Nullsv;
+
+ switch (obase->op_type) {
+
+ case OP_RV2AV:
+ case OP_RV2HV:
+ case OP_PADAV:
+ case OP_PADHV:
+ {
+ const bool pad = (obase->op_type == OP_PADAV || obase->op_type == OP_PADHV);
+ const bool hash = (obase->op_type == OP_PADHV || obase->op_type == OP_RV2HV);
+ I32 index = 0;
+ SV *keysv = Nullsv;
+ int subscript_type = FUV_SUBSCRIPT_WITHIN;
+
+ if (pad) { /* @lex, %lex */
+ sv = PAD_SVl(obase->op_targ);
+ gv = Nullgv;
+ }
+ else {
+ if (cUNOPx(obase)->op_first->op_type == OP_GV) {
+ /* @global, %global */
+ gv = cGVOPx_gv(cUNOPx(obase)->op_first);
+ if (!gv)
+ break;
+ sv = hash ? (SV*)GvHV(gv): (SV*)GvAV(gv);
+ }
+ else /* @{expr}, %{expr} */
+ return find_uninit_var(cUNOPx(obase)->op_first,
+ uninit_sv, match);
+ }
+
+ /* attempt to find a match within the aggregate */
+ if (hash) {
+ keysv = S_find_hash_subscript(aTHX_ (HV*)sv, uninit_sv);
+ if (keysv)
+ subscript_type = FUV_SUBSCRIPT_HASH;
+ }
+ else {
+ index = S_find_array_subscript(aTHX_ (AV*)sv, uninit_sv);
+ if (index >= 0)
+ subscript_type = FUV_SUBSCRIPT_ARRAY;
+ }
+
+ if (match && subscript_type == FUV_SUBSCRIPT_WITHIN)
+ break;
+
+ 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 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 varname(gv, '$', 0, Nullsv, 0, FUV_SUBSCRIPT_NONE);
+
+ case OP_AELEMFAST:
+ if (obase->op_flags & OPf_SPECIAL) { /* lexical array */
+ if (match) {
+ SV **svp;
+ av = (AV*)PAD_SV(obase->op_targ);
+ if (!av || SvRMAGICAL(av))
+ break;
+ svp = av_fetch(av, (I32)obase->op_private, FALSE);
+ if (!svp || *svp != uninit_sv)
+ break;
+ }
+ return varname(Nullgv, '$', obase->op_targ,
+ Nullsv, (I32)obase->op_private, FUV_SUBSCRIPT_ARRAY);
+ }
+ else {
+ gv = cGVOPx_gv(obase);
+ if (!gv)
+ break;
+ if (match) {
+ SV **svp;
+ av = GvAV(gv);
+ if (!av || SvRMAGICAL(av))
+ break;
+ svp = av_fetch(av, (I32)obase->op_private, FALSE);
+ if (!svp || *svp != uninit_sv)
+ break;
+ }
+ return varname(gv, '$', 0,
+ Nullsv, (I32)obase->op_private, FUV_SUBSCRIPT_ARRAY);
+ }
+ break;
+
+ case OP_EXISTS:
+ o = cUNOPx(obase)->op_first;
+ if (!o || o->op_type != OP_NULL ||
+ ! (o->op_targ == OP_AELEM || o->op_targ == OP_HELEM))
+ break;
+ return find_uninit_var(cBINOPo->op_last, uninit_sv, match);
+
+ case OP_AELEM:
+ case OP_HELEM:
+ if (PL_op == obase)
+ /* $a[uninit_expr] or $h{uninit_expr} */
+ return find_uninit_var(cBINOPx(obase)->op_last, uninit_sv, match);
+
+ gv = Nullgv;
+ o = cBINOPx(obase)->op_first;
+ kid = cBINOPx(obase)->op_last;
+
+ /* get the av or hv, and optionally the gv */
+ sv = Nullsv;
+ if (o->op_type == OP_PADAV || o->op_type == OP_PADHV) {
+ sv = PAD_SV(o->op_targ);
+ }
+ else if ((o->op_type == OP_RV2AV || o->op_type == OP_RV2HV)
+ && cUNOPo->op_first->op_type == OP_GV)
+ {
+ gv = cGVOPx_gv(cUNOPo->op_first);
+ if (!gv)
+ break;
+ sv = o->op_type == OP_RV2HV ? (SV*)GvHV(gv) : (SV*)GvAV(gv);
+ }
+ if (!sv)
+ break;
+
+ if (kid && kid->op_type == OP_CONST && SvOK(cSVOPx_sv(kid))) {
+ /* index is constant */
+ if (match) {
+ if (SvMAGICAL(sv))
+ break;
+ if (obase->op_type == OP_HELEM) {
+ HE* he = hv_fetch_ent((HV*)sv, cSVOPx_sv(kid), 0, 0);
+ if (!he || HeVAL(he) != uninit_sv)
+ break;
+ }
+ else {
+ 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 varname(gv, '%', o->op_targ,
+ cSVOPx_sv(kid), 0, FUV_SUBSCRIPT_HASH);
+ else
+ return varname(gv, '@', o->op_targ, Nullsv,
+ SvIV(cSVOPx_sv(kid)), FUV_SUBSCRIPT_ARRAY);
+ ;
+ }
+ else {
+ /* index is an expression;
+ * attempt to find a match within the aggregate */
+ if (obase->op_type == OP_HELEM) {
+ SV * const keysv = S_find_hash_subscript(aTHX_ (HV*)sv, uninit_sv);
+ if (keysv)
+ 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 varname(gv, '@', o->op_targ,
+ Nullsv, index, FUV_SUBSCRIPT_ARRAY);
+ }
+ if (match)
+ break;
+ return varname(gv,
+ (o->op_type == OP_PADAV || o->op_type == OP_RV2AV)
+ ? '@' : '%',
+ o->op_targ, Nullsv, 0, FUV_SUBSCRIPT_WITHIN);
+ }
+
+ break;
+
+ case OP_AASSIGN:
+ /* only examine RHS */
+ return find_uninit_var(cBINOPx(obase)->op_first, uninit_sv, match);
+
+ case OP_OPEN:
+ o = cUNOPx(obase)->op_first;
+ if (o->op_type == OP_PUSHMARK)
+ o = o->op_sibling;
+
+ if (!o->op_sibling) {
+ /* one-arg version of open is highly magical */
+
+ if (o->op_type == OP_GV) { /* open FOO; */
+ gv = cGVOPx_gv(o);
+ if (match && GvSV(gv) != uninit_sv)
+ break;
+ return varname(gv, '$', 0,
+ Nullsv, 0, FUV_SUBSCRIPT_NONE);
+ }
+ /* other possibilities not handled are:
+ * open $x; or open my $x; should return '${*$x}'
+ * open expr; should return '$'.expr ideally
+ */
+ break;
+ }
+ goto do_op;
+
+ /* ops where $_ may be an implicit arg */
+ case OP_TRANS:
+ case OP_SUBST:
+ case OP_MATCH:
+ if ( !(obase->op_flags & OPf_STACKED)) {
+ if (uninit_sv == ((obase->op_private & OPpTARGET_MY)
+ ? PAD_SVl(obase->op_targ)
+ : DEFSV))
+ {
+ sv = sv_newmortal();
+ sv_setpvn(sv, "$_", 2);
+ return sv;
+ }
+ }
+ goto do_op;
+
+ case OP_PRTF:
+ case OP_PRINT:
+ /* skip filehandle as it can't produce 'undef' warning */
+ o = cUNOPx(obase)->op_first;
+ if ((obase->op_flags & OPf_STACKED) && o->op_type == OP_PUSHMARK)
+ o = o->op_sibling->op_sibling;
+ goto do_op2;
+
+
+ case OP_RV2SV:
+ case OP_CUSTOM:
+ case OP_ENTERSUB:
+ match = 1; /* XS or custom code could trigger random warnings */
+ goto do_op;
+
+ case OP_SCHOMP:
+ case OP_CHOMP:
+ if (SvROK(PL_rs) && uninit_sv == SvRV(PL_rs))
+ return sv_2mortal(newSVpvn("${$/}", 5));
+ /* FALL THROUGH */
+
+ default:
+ do_op:
+ if (!(obase->op_flags & OPf_KIDS))
+ break;
+ o = cUNOPx(obase)->op_first;
+
+ do_op2:
+ if (!o)
+ break;
+
+ /* if all except one arg are constant, or have no side-effects,
+ * or are optimized away, then it's unambiguous */
+ o2 = Nullop;
+ for (kid=o; kid; kid = kid->op_sibling) {
+ if (kid &&
+ ( (kid->op_type == OP_CONST && SvOK(cSVOPx_sv(kid)))
+ || (kid->op_type == OP_NULL && ! (kid->op_flags & OPf_KIDS))
+ || (kid->op_type == OP_PUSHMARK)
+ )
+ )
+ continue;
+ if (o2) { /* more than one found */
+ o2 = Nullop;
+ break;
+ }
+ o2 = kid;
+ }
+ if (o2)
+ return find_uninit_var(o2, uninit_sv, match);
+
+ /* scan all args */
+ while (o) {
+ sv = find_uninit_var(o, uninit_sv, 1);
+ if (sv)
+ return sv;
+ o = o->op_sibling;
+ }
+ break;
+ }
+ return Nullsv;
+}
+
+
+/*
+=for apidoc report_uninit
+
+Print appropriate "Use of uninitialized variable" warning
+
+=cut
+*/
+
+void
+Perl_report_uninit(pTHX_ SV* uninit_sv)
+{
+ if (PL_op) {
+ SV* varname = Nullsv;
+ if (uninit_sv) {
+ varname = find_uninit_var(PL_op, uninit_sv,0);
+ if (varname)
+ sv_insert(varname, 0, 0, " ", 1);
+ }
+ Perl_warner(aTHX_ packWARN(WARN_UNINITIALIZED), PL_warn_uninit,
+ varname ? SvPV_nolen_const(varname) : "",
+ " in ", OP_DESC(PL_op));
+ }
+ else
+ Perl_warner(aTHX_ packWARN(WARN_UNINITIALIZED), PL_warn_uninit,
+ "", "", "");