Build the isa cache from any linear ISA, rather than forcing the use

of dfs. This avoids calling dfs on a C3 class (and all its parents),
which won't break anything, but is more work than is needed.

p4raw-id: //depot/perl@34356

1 files changed, 22 insertions, 3 deletions

diff --git a/mro.c b/mro.c
index 4d7ade5747..b15ec3a69c 100644
--- a/mro.c
+++ b/mro.c
@@ -105,9 +105,28 @@ Perl_get_isa_hash(pTHX_ HV *const stash)
 
     PERL_ARGS_ASSERT_GET_ISA_HASH;
 
-    if (!meta->isa)
-	mro_get_linear_isa_dfs(stash, 0);
-    assert(meta->isa);
+    if (!meta->isa) {
+	AV *const isa = mro_get_linear_isa(stash);
+	if (!meta->isa) {
+	    HV *const isa_hash = newHV();
+	    /* Linearisation didn't build it for us, so do it here.  */
+	    SV *const *svp = AvARRAY(isa);
+	    SV *const *const svp_end = svp + AvFILLp(isa) + 1;
+	    const HEK *const canon_name = HvNAME_HEK(stash);
+
+	    while (svp < svp_end) {
+		(void) hv_store_ent(isa_hash, *svp++, &PL_sv_undef, 0);
+	    }
+
+	    (void) hv_common(isa_hash, NULL, HEK_KEY(canon_name),
+			     HEK_LEN(canon_name), HEK_FLAGS(canon_name),
+			     HV_FETCH_ISSTORE, &PL_sv_undef,
+			     HEK_HASH(canon_name));
+	    (void) hv_store(isa_hash, "UNIVERSAL", 9, &PL_sv_undef, 0);
+
+	    meta->isa = isa_hash;
+	}
+    }
     return meta->isa;
 }