fixup to "avoid identical stack traces" - try 2

GH #15109, #17567

[ this commit was originally applied as v5.31.9-121-gfb8188b84d, but was
quickly reverted by v5.31.9-124-g6311900a66. I'm now -re-applying it,
but with a 'SAVEFREEOP(PL_curcop)' added, which was missing from the
original commit. ]

My original fix for this issue, v5.31.6-141-gf2f32cd638
made a shallow copy of &PL_compiling. However, for non-default
warning bits, this made two COPs share the malloced() cop_warnings,
and bad things ensured. In particular this was flagged up in:

    GH #17567: "BBC: AYOUNG/OpenVZ-0.01.tar.gz"

The fix in this commit is to do a deep copy of the COP using
newSTATEOP().

1 files changed, 3 insertions, 4 deletions

diff --git a/op.c b/op.c
index 954bb32f57..0b8e961803 100644
--- a/op.c
+++ b/op.c
@@ -11712,10 +11712,9 @@ S_process_special_blocks(pTHX_ I32 floor, const char *const fullname,
                  * to PL_compiling, IN_PERL_COMPILETIME/IN_PERL_RUNTIME
                  * will give the wrong answer.
                  */
-                Newx(PL_curcop, 1, COP);
-                StructCopy(&PL_compiling, PL_curcop, COP);
-                PL_curcop->op_slabbed = 0;
-                SAVEFREEPV(PL_curcop);
+                PL_curcop = (COP*)newSTATEOP(PL_compiling.op_flags, NULL, NULL);
+                CopLINE_set(PL_curcop, CopLINE(&PL_compiling));
+                SAVEFREEOP(PL_curcop);
             }
 
             PUSHSTACKi(PERLSI_REQUIRE);