Clarify in documentation the distinction between sv_isa_sv() and the much older sv_isa()

leonerd · leonerd · commit 6a02a2592878 · 2019-11-30T20:18:07.000Z
diff --git a/sv.c b/sv.c
@@ -10301,8 +10301,12 @@ Perl_sv_isobject(pTHX_ SV *sv)
 =for apidoc sv_isa
 
 Returns a boolean indicating whether the SV is blessed into the specified
-class.  This does not check for subtypes; use C<sv_derived_from> to verify
-an inheritance relationship.
+class.
+
+This does not check for subtypes or method overloading. Use C<sv_isa_sv> to
+verify an inheritance relationship in the same way as the C<isa> operator by
+respecting any C<isa()> method overloading; or C<sv_derived_from_sv> to test
+directly on the actual object type.
 
 =cut
 */
diff --git a/universal.c b/universal.c
@@ -197,6 +197,9 @@ not derived from the specified class.
 
 This is the function used to implement the behaviour of the C<isa> operator.
 
+Not to be confused with the older C<sv_isa> function, which does not use an
+overloaded C<isa()> method, nor will check subclassing.
+
 =cut
 
 */
