pp_ctl.c - try_run_unitcheck() guard against leaking PL_restartop

If we die while executing a UNITCHECK inside of an eval we shouldn't
leave PL_restartop set, as we will execute PL_op->op_next anyway.
I couldn't get anything to SEGV with code related to this, but I could
get asserts() to trip to show the leaking PL_restartop. This maintains
equivalence with try_yyparse() which does need it for sure.

Author: demerphq

pp_ctl.c

@@ -3570,17 +3570,31 @@ S_try_yyparse(pTHX_ int gramtype, OP *caller_op)
  *   3: a unitcheck block died
  */
 STATIC int
-S_try_run_unitcheck(pTHX)
+S_try_run_unitcheck(pTHX, OP* caller_op)
 {
-    int ret;
+    /* if we die during compilation PL_restartop and PL_restartjmpenv
+     * will be set. We need to restore their values if that happens. */
+    JMPENV *restartjmpenv = PL_restartjmpenv;
+    OP *restartop = PL_restartop;
     dJMPENV;
+    int ret;
+
+    assert(CxTYPE(CX_CUR()) == CXt_EVAL);
     JMPENV_PUSH(ret);
     switch (ret) {
     case 0:
         call_list(PL_scopestack_ix, PL_unitcheckav);
         break;
     case 3:
         /* call_list died */
+        /* call_list() died and we trapped the error. We should restore
+         * the old PL_restartjmpenv and PL_restartop values, as they are
+         * used only in the case where the code was actually run.
+         * The assert validates that we will still execute the PL_restartop.
+         */
+        assert(PL_restartop == caller_op->op_next); /* we expect these to match */
+        PL_restartjmpenv = restartjmpenv;
+        PL_restartop = restartop;
         break;
     default:
         JMPENV_POP;
@@ -3804,7 +3818,7 @@ S_doeval_compile(pTHX_ U8 gimme, CV* outside, U32 seq, HV *hh)
         if (in_require) {
             call_list(PL_scopestack_ix, PL_unitcheckav);
         }
-        else if (S_try_run_unitcheck(aTHX)) {
+        else if (S_try_run_unitcheck(aTHX, saveop)) {
             /* there was an error! */
 
             /* Restore PL_OP */