[perl #124160] Disable targlex for state var init

The targlex optimisation optimises away an assignment to a lexical
variable, having the operator on the rhs write directly to the lexi-
cal itself.  This optimisation has a bug in it (#101640) that causes
$lex = "a $b c" to stringify the result, instead of allowing con-
cat overloding to return something other than a string.  I extended
the optimisation to occur with state variable initialization, in
v5.21.5-366-ga1b22ab, not realising it would make an existing bug
occur more often.  For now, just disable the new optimisation.

1 files changed, 7 insertions, 1 deletions

diff --git a/t/opbasic/concat.t b/t/opbasic/concat.t
index f020992ac8..9c4cbe20e2 100644
--- a/t/opbasic/concat.t
+++ b/t/opbasic/concat.t
@@ -22,7 +22,7 @@ sub ok {
     return $ok;
 }
 
-print "1..30\n";
+print "1..31\n";
 
 ($a, $b, $c) = qw(foo bar);
 
@@ -163,3 +163,9 @@ sub beq { use bytes; $_[0] eq $_[1]; }
     $x .= "-append-";
     ok($x eq "ab-append-", "Appending to something initialized using constant folding");
 }
+
+# [perl #124160]
+package o { use overload "." => sub { $_[0] }, fallback => 1 }
+$o = bless [], "o";
+ok(ref(CORE::state $y = "a $o b") eq 'o',
+  'state $y = "foo $bar baz" does not stringify; only concats');