Return nothing, instead of undef, when can() is called with missing m…

…ethods

t/uni/universal.t

@@ -13,7 +13,7 @@ BEGIN {
 use utf8;
 use open qw( :utf8 :std );
 
-plan tests => 103;
+plan tests => 105;
 
 $a = {};
 bless $a, "Bòb";
@@ -195,3 +195,11 @@ ok( scalar $child->can(qw(bar baz)), 'can(@methods) in scalar content should ret
 
 ok( !Child->can(qw(foo baz no_such_method)), 'can(@methods) with non-existent methods should already return nothing' );
 ok( !scalar Child->can(qw(foo baz no_such_method)), 'can(@methods) with non-existent methods should return false in scalar context' );
+
+#
+# Check that can() returns an empty list when called with missing methods
+#
+@methods = Child->can(qw(no_such_method));
+ok( !@methods, 'can(@methods) with non-existent methods should already return nothing even when assigned to an array' );
+@methods = $child->can(qw(no_such_method));
+ok( !@methods, 'can(@methods) with non-existent methods should return even when assigned to an array' );

universal.c

@@ -488,7 +488,7 @@ XS(XS_UNIVERSAL_can)
        precedence here over the numeric form, as (!1)->foo treats the
        invocant as the empty string, though it is a dualvar. */
     if (!SvOK(sv) || (SvPOK(sv) && !SvCUR(sv)))
-        XSRETURN_UNDEF;
+        XSRETURN_EMPTY;
 
     if (SvROK(sv)) {
         sv = MUTABLE_SV(SvRV(sv));
@@ -512,15 +512,15 @@ XS(XS_UNIVERSAL_can)
         for (i = 1; i < items; i++) {
             GV * const gv = gv_fetchmethod_sv_flags(pkg, ST(i), 0);
             if (!gv || !isGV(gv) || !GvCV(gv))
-                XSRETURN_UNDEF;
+                XSRETURN_EMPTY;
             else {
                 ST(i-1) = sv_2mortal(newRV(MUTABLE_SV(GvCV(gv))));
             }
         }
         XSRETURN(items - 1);
     }
 
-    XSRETURN_UNDEF;
+    XSRETURN_EMPTY;
 }
 
 XS(XS_UNIVERSAL_DOES); /* prototype to pass -Wmissing-prototypes */