revert smartmatch to 5.27.6 behaviour

The pumpking has determined that the CPAN breakage caused by changing
smartmatch [perl #132594] is too great for the smartmatch changes to
stay in for 5.28.

This reverts most of the merge in commit
da4e040f42421764ef069371d77c008e6b801f45.  All core behaviour and
documentation is reverted.  The removal of use of smartmatch from a couple
of tests (that aren't testing smartmatch) remains.  Customisation of
a couple of CPAN modules to make them portable across smartmatch types
remains.  A small bugfix in scope.c also remains.

1 files changed, 16 insertions, 8 deletions

diff --git a/cop.h b/cop.h
index f6853573b3..5c66752859 100644
--- a/cop.h
+++ b/cop.h
@@ -721,9 +721,10 @@ struct block_loop {
 
 
 
-/* whereso context */
-struct block_whereso {
+/* given/when context */
+struct block_givwhen {
 	OP *leave_op;
+        SV *defsv_save; /* the original $_ */
 };
 
 
@@ -747,7 +748,7 @@ struct block {
 	struct block_format	blku_format;
 	struct block_eval	blku_eval;
 	struct block_loop	blku_loop;
-	struct block_whereso	blku_whereso;
+	struct block_givwhen	blku_givwhen;
     } blk_u;
 };
 #define blk_oldsp	cx_u.cx_blk.blku_oldsp
@@ -763,7 +764,7 @@ struct block {
 #define blk_format	cx_u.cx_blk.blk_u.blku_format
 #define blk_eval	cx_u.cx_blk.blk_u.blku_eval
 #define blk_loop	cx_u.cx_blk.blk_u.blku_loop
-#define blk_whereso	cx_u.cx_blk.blk_u.blku_whereso
+#define blk_givwhen	cx_u.cx_blk.blk_u.blku_givwhen
 
 #define CX_DEBUG(cx, action)						\
     DEBUG_l(								\
@@ -856,11 +857,16 @@ struct context {
    and a static array of context names in pp_ctl.c  */
 #define CXTYPEMASK	0xf
 #define CXt_NULL	0 /* currently only used for sort BLOCK */
-#define CXt_WHERESO	1
+#define CXt_WHEN	1
 #define CXt_BLOCK	2
-/* be careful of the ordering of these six. Macros like CxTYPE_is_LOOP,
+/* When micro-optimising :-) keep GIVEN next to the LOOPs, as these 5 share a
+   jump table in pp_ctl.c
+   The first 4 don't have a 'case' in at least one switch statement in pp_ctl.c
+*/
+#define CXt_GIVEN	3
+
+/* be careful of the ordering of these five. Macros like CxTYPE_is_LOOP,
  * CxFOREACH compare ranges */
-#define CXt_LOOP_GIVEN	3 /* given (...)    { ...; } */
 #define CXt_LOOP_ARY	4 /* for (@ary)     { ...; } */
 #define CXt_LOOP_LAZYSV	5 /* for ('a'..'z') { ...; } */
 #define CXt_LOOP_LAZYIV	6 /* for (1..9)     { ...; } */
@@ -886,6 +892,8 @@ struct context {
 
 /* private flags for CXt_LOOP */
 
+/* this is only set in conjunction with CXp_FOR_GV */
+#define CXp_FOR_DEF	0x10	/* foreach using $_ */
 /* these 3 are mutually exclusive */
 #define CXp_FOR_LVREF	0x20	/* foreach using \$var */
 #define CXp_FOR_GV	0x40	/* foreach using package var */
@@ -897,7 +905,7 @@ struct context {
 #define CXp_ONCE	0x10	/* What was sbu_once in struct subst */
 
 #define CxTYPE(c)	((c)->cx_type & CXTYPEMASK)
-#define CxTYPE_is_LOOP(c) (   CxTYPE(cx) >= CXt_LOOP_GIVEN              \
+#define CxTYPE_is_LOOP(c) (   CxTYPE(cx) >= CXt_LOOP_ARY                \
                            && CxTYPE(cx) <= CXt_LOOP_PLAIN)
 #define CxMULTICALL(c)	((c)->cx_type & CXp_MULTICALL)
 #define CxREALEVAL(c)	(((c)->cx_type & (CXTYPEMASK|CXp_REAL))		\