Enforce strict 'subs' in multideref optimisation

The code that checks constant keys and turns them into HEKs swallowed
the OP_CONST before the strictness checker could get to it, thus
allowing barewords when they should not be.

2 files changed, 17 insertions, 0 deletions

diff --git a/op.c b/op.c
index ee31adcb57..28500e31c2 100644
--- a/op.c
+++ b/op.c
@@ -2343,6 +2343,13 @@ S_check_hash_fields_and_hekify(pTHX_ UNOP *rop, SVOP *key_op)
             continue;
         svp = cSVOPx_svp(key_op);
 
+        /* make sure it's not a bareword under strict subs */
+        if (key_op->op_private & OPpCONST_BARE &&
+            key_op->op_private & OPpCONST_STRICT)
+        {
+            no_bareword_allowed((OP*)key_op);
+        }
+
         /* Make the CONST have a shared SV */
         if (   !SvIsCOW_shared_hash(sv = *svp)
             && SvTYPE(sv) < SVt_PVMG
diff --git a/t/lib/strict/subs b/t/lib/strict/subs
index 095adee4cf..bad22c6a46 100644
--- a/t/lib/strict/subs
+++ b/t/lib/strict/subs
@@ -458,3 +458,13 @@ use strict 'subs';
 EXPECT
 Bareword "FOO" not allowed while "strict subs" in use at - line 3.
 Execution of - aborted due to compilation errors.
+########
+# [perl #126981] Strict subs vs. multideref
+sub CONST () { 'some_key' }
+my $h;
+my $v1 = $h->{+CONST_TYPO};
+use strict 'subs';
+my $v2 = $h->{+CONST_TYPO};
+EXPECT
+Bareword "CONST_TYPO" not allowed while "strict subs" in use at - line 6.
+Execution of - aborted due to compilation errors.