[perl #78634] Conflict in defining constant INIT

When gv_init tries to turn a constant named INIT into a CV, the auto-
matic special processing of the INIT ‘block’ kicks in, which removes
the CV from the GV.

This should not happen with gv_init, as $::{INIT} = \5 is supposed
to be equivalent to *INIT = sub(){5}, which does not do that.

This commit makes gv_init check for that, increase the reference
count, and reassign the CV. It does not stop the CV from being called
as a special block, but it is harmless to call a constant CV.

1 files changed, 3 insertions, 0 deletions

diff --git a/gv.c b/gv.c
index b2cb5a4146..f51839e6a8 100644
--- a/gv.c
+++ b/gv.c
@@ -317,6 +317,9 @@ Perl_gv_init(pTHX_ GV *gv, HV *stash, const char *name, STRLEN len, int multi)
 
 	    /* newCONSTSUB takes ownership of the reference from us.  */
 	    cv = newCONSTSUB(stash, (name0 ? name0 : name), has_constant);
+	    /* In case op.c:S_process_special_blocks stole it: */
+	    if (!GvCV(gv))
+		GvCV(gv) = SvREFCNT_inc_simple_NN(cv);
 	    assert(GvCV(gv) == cv); /* newCONSTSUB should have set this */
 	    if (name0)
 		Safefree(name0);