smartmatch: fail to find the loop instead of crashing

dopoptoloop() or dopoptolabel() would find a loop outside the sub
called from call_sv() and rewind the context and save stack to outside
the context set up by call_sv(), crashes and panics ensure.

Switching stacks here also starts a new context stack, so the outer
loop isn't found and we don't crash.

Most other callers to call_sv() (or call_method() etc) do the same.

I'm not entirely sure about passing flags = 1 to push_stackinfo(),
this matches pp_sort, but not other callers.

Fixes #16608

Author: tonycoz

cop.h

@@ -1258,6 +1258,7 @@ struct context {
 #define PERLSI_REQUIRE		9
 #define PERLSI_MULTICALL       10
 #define PERLSI_REGCOMP         11
+#define PERLSI_SMARTMATCH      12
 
 struct stackinfo {
     AV *		si_stack;	/* stack for current runlevel */

deb.c

@@ -237,7 +237,8 @@ static const char * const si_names[] = {
     "DIEHOOK",
     "REQUIRE",
     "MULTICALL",
-    "REGCOMP"
+    "REGCOMP",
+    "SMARTMATCH"
 };
 #endif
 

pp_ctl.c

@@ -5941,6 +5941,7 @@ S_do_smartmatch(pTHX_ HV *seen_this, HV *seen_other, const bool copied)
             DEBUG_M(Perl_deb(aTHX_ "    applying rule Hash-CodeRef\n"));
             if (numkeys == 0)
                 goto ret_yes;
+            push_stackinfo(PERLSI_SMARTMATCH, 1);
             while ( (he = hv_iternext(hv)) ) {
                 DEBUG_M(Perl_deb(aTHX_ "        testing hash key...\n"));
                 ENTER_with_name("smartmatch_hash_key_test");
@@ -5953,6 +5954,7 @@ S_do_smartmatch(pTHX_ HV *seen_this, HV *seen_other, const bool copied)
                 FREETMPS;
                 LEAVE_with_name("smartmatch_hash_key_test");
             }
+            pop_stackinfo();
             if (andedresults)
                 goto ret_yes;
             else
@@ -5967,6 +5969,7 @@ S_do_smartmatch(pTHX_ HV *seen_this, HV *seen_other, const bool copied)
             DEBUG_M(Perl_deb(aTHX_ "    applying rule Array-CodeRef\n"));
             if (len == 0)
                 goto ret_yes;
+            push_stackinfo(PERLSI_SMARTMATCH, 1);
             for (i = 0; i < len; ++i) {
                 SV * const * const svp = av_fetch(av, i, FALSE);
                 DEBUG_M(Perl_deb(aTHX_ "        testing array element...\n"));
@@ -5981,6 +5984,7 @@ S_do_smartmatch(pTHX_ HV *seen_this, HV *seen_other, const bool copied)
                 FREETMPS;
                 LEAVE_with_name("smartmatch_array_elem_test");
             }
+            pop_stackinfo();
             if (andedresults)
                 goto ret_yes;
             else
@@ -5989,12 +5993,14 @@ S_do_smartmatch(pTHX_ HV *seen_this, HV *seen_other, const bool copied)
         else {
           sm_any_sub:
             DEBUG_M(Perl_deb(aTHX_ "    applying rule Any-CodeRef\n"));
+            push_stackinfo(PERLSI_SMARTMATCH, 1);
             ENTER_with_name("smartmatch_coderef");
             PUSHMARK(PL_stack_sp);
             rpp_xpush_1(d);
             (void)call_sv(e, G_SCALAR);
             LEAVE_with_name("smartmatch_coderef");
             SV *retsv = *PL_stack_sp--;
+            pop_stackinfo();
             rpp_replace_2_1(retsv);
 #ifdef PERL_RC_STACK
             SvREFCNT_dec(retsv);

t/lib/croak/pp_ctl

@@ -57,3 +57,71 @@ die;
 EXPECT
 Unmatched ) in regex; marked by <-- HERE in m/_) <-- HERE / at (eval 1) line 1.
 	...propagated at - line 2.
+########
+# NAME last from smartmatch CV
+0 ~~ sub {last} for 0
+EXPECT
+Can't "last" outside a loop block at - line 1.
+########
+# NAME redo from smartmatch CV
+0 ~~ sub {redo} for 0
+EXPECT
+Can't "redo" outside a loop block at - line 1.
+########
+# NAME next from smartmatch CV
+0 ~~ sub {next} for 0
+EXPECT
+Can't "next" outside a loop block at - line 1.
+########
+# NAME goto loop label from smartmatch CV
+FOO: 0~~sub{goto FOO} for 0
+EXPECT
+Can't find label FOO at - line 1.
+########
+# NAME last from smartmatch CV against array
+my @x = (0);
+@x ~~ sub {last} for 0
+EXPECT
+Can't "last" outside a loop block at - line 2.
+########
+# NAME redo from smartmatch CV against array
+my @x = (0);
+@x ~~ sub {redo} for 0
+EXPECT
+Can't "redo" outside a loop block at - line 2.
+########
+# NAME next from smartmatch CV against array
+my @x = (0);
+@x ~~ sub {next} for 0
+EXPECT
+Can't "next" outside a loop block at - line 2.
+########
+# NAME goto loop label from smartmatch CV against array
+my @x = (0);
+FOO:@x ~~sub{goto FOO} for 0
+EXPECT
+Can't find label FOO at - line 2.
+########
+# NAME last from smartmatch CV against hash
+my %x = qw(a b);
+%x ~~ sub {last} for 0
+EXPECT
+Can't "last" outside a loop block at - line 2.
+########
+# NAME redo from smartmatch CV against hash
+my %x = qw(a b);
+%x ~~ sub {redo} for 0
+EXPECT
+Can't "redo" outside a loop block at - line 2.
+########
+# NAME next from smartmatch CV against hash
+my %x = qw(a b);
+%x ~~ sub {next} for 0
+EXPECT
+Can't "next" outside a loop block at - line 2.
+########
+# NAME goto loop label from smartmatch CV against hash
+my %x = qw(a b);
+FOO:%x ~~sub{goto FOO} for 0
+EXPECT
+Can't find label FOO at - line 2.