Eliminate opASSIGN macro usage from core

This macro is defined as

    (PL_op->op_flags & OPf_STACKED)

and indicates, for ops which support it, that the mutator-variant of the
op is present (e.g. $x += 1).

This macro was mainly used as an arg for the old-style overloading
macros (tryAMAGICbin()) which were eliminated several years ago.

This commit removes its vestigial usage, and instead tests OPf_STACKED
directly at each location, along with adding a comment about the
significance of the flag.

This removes one item of obfuscation from the overloading code.

There is one potentially functional change in this commit:
Perl_try_amagic_bin() was sometimes testing for OPf_STACKED without
first checking that it had been called with the AMGf_assign flag (which
indicates that this op supports a mutator variant). With this commit, it
now checks first, so this is theoretically a bug fix. In practice that
section of code was never reached without AMGf_assign always being set
anyway.

1 files changed, 7 insertions, 3 deletions

diff --git a/gv.c b/gv.c
index 798c3ae92f..f7ffbfa9ed 100644
--- a/gv.c
+++ b/gv.c
@@ -2998,8 +2998,12 @@ Perl_try_amagic_bin(pTHX_ int method, int flags) {
 	SvGETMAGIC(right);
 
     if (SvAMAGIC(left) || SvAMAGIC(right)) {
-	SV * const tmpsv = amagic_call(left, right, method,
-		    ((flags & AMGf_assign) && opASSIGN ? AMGf_assign: 0)
+	SV * tmpsv;
+        /* STACKED implies mutator variant, e.g. $x += 1 */
+        bool mutator = (flags & AMGf_assign) && (PL_op->op_flags & OPf_STACKED);
+
+	tmpsv = amagic_call(left, right, method,
+		    (mutator ? AMGf_assign: 0)
 		  | (flags & AMGf_numarg));
 	if (tmpsv) {
 	    if (flags & AMGf_set) {
@@ -3009,7 +3013,7 @@ Perl_try_amagic_bin(pTHX_ int method, int flags) {
 	    else {
 		dATARGET;
 		(void)POPs;
-		if (opASSIGN || SvPADMY(TARG)) {
+		if (mutator || SvPADMY(TARG)) {
 		    sv_setsv(TARG, tmpsv);
 		    SETTARG;
 		}