make overload respect get magic

In most places, ops checked their args for overload *before* doing
mg_get(). This meant that, among other issues, tied vars that
returned overloaded objects wouldn't trigger calling the
overloaded method.  (Actually, for tied and arrays and hashes, it
still often would since mg_get gets called beforehand in rvalue
context).

This patch does the following:

Makes sure get magic is called first.

Moves most of the overload code formerly included by macros at the
start of each pp function into the separate helper functions
Perl_try_amagic_bin, Perl_try_amagic_un, S_try_amagic_ftest,
with 3 new wrapper macros:
tryAMAGICbin_MG, tryAMAGICun_MG, tryAMAGICftest_MG.
This made the code 3800 bytes smaller.

Makes sure that FETCH is not called multiple times. Much of this
bit was helped by some earlier work from Father Chrysostomos.

Added new functions and macros sv_inc_nomg(), sv_dec_nomg(),
dPOPnv_nomg, dPOPXiirl_ul_nomg, dPOPTOPnnrl_nomg, dPOPTOPiirl_ul_nomg
dPOPTOPiirl_nomg, SvIV_please_nomg, SvNV_nomg (again, some of
these were based on Father Chrysostomos's work).

Fixed the list version of the repeat operator (x): it now only
calls overloaded methods for the scalar version:
    (1,2,$overloaded) x 10
no longer erroneously calls
    x_method($overloaded,10))

The only thing I haven't checked/fixed yet is overloading the
iterator operator, <>.

1 files changed, 7 insertions, 0 deletions

diff --git a/sv.h b/sv.h
index 97a6c53d29..cc7edb9049 100644
--- a/sv.h
+++ b/sv.h
@@ -1163,6 +1163,9 @@ the scalar's value cannot change unless written to.
 #define SvIV_please(sv) \
 	STMT_START {if (!SvIOKp(sv) && (SvNOK(sv) || SvPOK(sv))) \
 		(void) SvIV(sv); } STMT_END
+#define SvIV_please_nomg(sv) \
+	STMT_START {if (!SvIOKp(sv) && (SvNOK(sv) || SvPOK(sv))) \
+		(void) SvIV_nomg(sv); } STMT_END
 #define SvIV_set(sv, val) \
 	STMT_START { assert(SvTYPE(sv) == SVt_IV || SvTYPE(sv) >= SVt_PVIV); \
 		assert(SvTYPE(sv) != SVt_PVAV);		\
@@ -1419,6 +1422,9 @@ otherwise use the more efficient C<SvIV>.
 Coerce the given SV to a double and return it. See C<SvNVx> for a version
 which guarantees to evaluate sv only once.
 
+=for apidoc Am|NV|SvNV_nomg|SV* sv
+Like C<SvNV> but doesn't process magic.
+
 =for apidoc Am|NV|SvNVx|SV* sv
 Coerces the given SV to a double and returns it. Guarantees to evaluate
 C<sv> only once. Only use this if C<sv> is an expression with side effects,
@@ -1510,6 +1516,7 @@ Like sv_utf8_upgrade, but doesn't do magic on C<sv>
 
 #define SvIV_nomg(sv) (SvIOK(sv) ? SvIVX(sv) : sv_2iv_flags(sv, 0))
 #define SvUV_nomg(sv) (SvIOK(sv) ? SvUVX(sv) : sv_2uv_flags(sv, 0))
+#define SvNV_nomg(sv) (SvNOK(sv) ? SvNVX(sv) : sv_2nv_flags(sv, 0))
 
 /* ----*/