Make sort’s warnings dependent on the right hints

sort’s warnings about uninitialized (or non-numeric) values returned
from comparison routines are emitted in the scope of the compar-
ison routine, not the sort function itself.  So, not only does
‘use warnings; sort...’ not always warn, but the line numbers can be
off, too:

$ ./perl -Ilib -e '()=sort flobbp 1,2;' -e'use warnings;sub flobbp{"foo"}'
Argument "foo" isn't numeric in sort at -e line 2.

The solution is to restore PL_curcop to its previous value before get-
ting a number out of the comparison routine’s return value.

1 files changed, 4 insertions, 0 deletions

diff --git a/pp_sort.c b/pp_sort.c
index da014e8073..6c2e301f7a 100644
--- a/pp_sort.c
+++ b/pp_sort.c
@@ -1765,6 +1765,7 @@ S_sortcv(pTHX_ SV *const a, SV *const b)
     I32 result;
     PMOP * const pm = PL_curpm;
     OP * const sortop = PL_op;
+    COP * const cop = PL_curcop;
     SV **pad;
  
     PERL_ARGS_ASSERT_SORTCV;
@@ -1777,6 +1778,7 @@ S_sortcv(pTHX_ SV *const a, SV *const b)
     if (PL_stack_sp != PL_stack_base + 1)
 	Perl_croak(aTHX_ "Sort subroutine didn't return single value");
     PL_op = sortop;
+    PL_curcop = cop;
     pad = PL_curpad; PL_curpad = 0;
     result = SvIV(*PL_stack_sp);
     PL_curpad = pad;
@@ -1798,6 +1800,7 @@ S_sortcv_stacked(pTHX_ SV *const a, SV *const b)
     AV * const av = GvAV(PL_defgv);
     PMOP * const pm = PL_curpm;
     OP * const sortop = PL_op;
+    COP * const cop = PL_curcop;
     SV **pad;
 
     PERL_ARGS_ASSERT_SORTCV_STACKED;
@@ -1830,6 +1833,7 @@ S_sortcv_stacked(pTHX_ SV *const a, SV *const b)
     if (PL_stack_sp != PL_stack_base + 1)
 	Perl_croak(aTHX_ "Sort subroutine didn't return single value");
     PL_op = sortop;
+    PL_curcop = cop;
     pad = PL_curpad; PL_curpad = 0;
     result = SvIV(*PL_stack_sp);
     PL_curpad = pad;