Use const repl optimisation with s///e where possible

In those cases where s///e contains a single variable or a sequence
that is folded to a const op, we can do away with substcont.

PMf_EVAL means that there was an /e.  But we don’t actually need to
check that; instead we can just examine the op tree, which we have to
do anyway.

The op tree that s//$x/e and s//"constant"/e compile down to have a
null (a do-block) containing a scope op (block with a single state-
ment, as opposed to op_leave which represents multiple statements)
containing a null followed by the constant or variable.

1 files changed, 1 insertions, 1 deletions

diff --git a/t/lib/warnings/9uninit b/t/lib/warnings/9uninit
index 717e7f6fb0..43069f56d4 100644
--- a/t/lib/warnings/9uninit
+++ b/t/lib/warnings/9uninit
@@ -883,7 +883,7 @@ Use of uninitialized value $m1 in regexp compilation at - line 41.
 Use of uninitialized value $g1 in substitution (s///) at - line 42.
 Use of uninitialized value $m1 in regexp compilation at - line 43.
 Use of uninitialized value $g1 in substitution iterator at - line 43.
-Use of uninitialized value $m1 in substitution iterator at - line 44.
+Use of uninitialized value $m1 in substitution (s///) at - line 44.
 Use of uninitialized value in substitution iterator at - line 47.
 ########
 use warnings 'uninitialized';