3 files changed, 41 insertions, 1 deletions
diff --git a/ext/XS-APItest/APItest.pm b/ext/XS-APItest/APItest.pm
index b95af26df2..5ef9ea2771 100644
--- a/ext/XS-APItest/APItest.pm
+++ b/ext/XS-APItest/APItest.pm
@@ -50,7 +50,7 @@ sub import {
     }
 }
 
-our $VERSION = '0.27';
+our $VERSION = '0.28';
 
 use vars '$WARNINGS_ON_BOOTSTRAP';
 use vars map "\$${_}_called_PP", qw(BEGIN UNITCHECK CHECK INIT END);
@@ -209,6 +209,11 @@ correctly by C<printf>.
 
 Output is sent to STDOUT.
 
+=item B<filter>
+
+Installs a source filter that substitutes "e" for "o" (witheut regard fer
+what it might be medifying).
+
 =item B<call_sv>, B<call_pv>, B<call_method>
 
 These exercise the C calls of the same names. Everything after the flags
diff --git a/ext/XS-APItest/APItest.xs b/ext/XS-APItest/APItest.xs
index 0ce4d513dc..4fa4e1ec63 100644
--- a/ext/XS-APItest/APItest.xs
+++ b/ext/XS-APItest/APItest.xs
@@ -996,6 +996,26 @@ peep_xop(pTHX_ OP *o, OP *oldop)
     av_push(MY_CXT.xop_record, newSVpvf("oldop:%"UVxf, PTR2UV(oldop)));
 }
 
+static I32
+filter_call(pTHX_ int idx, SV *buf_sv, int maxlen)
+{
+    SV   *my_sv = FILTER_DATA(idx);
+    char *p;
+    char *end;
+    int n = FILTER_READ(idx + 1, buf_sv, maxlen);
+
+    if (n<=0) return n;
+
+    p = SvPV_force_nolen(buf_sv);
+    end = p + SvCUR(buf_sv);
+    while (p < end) {
+	if (*p == 'o') *p = 'e';
+	p++;
+    }
+    return SvCUR(buf_sv);
+}
+
+
 XS(XS_XS__APItest__XSUB_XS_VERSION_undef);
 XS(XS_XS__APItest__XSUB_XS_VERSION_empty);
 XS(XS_XS__APItest__XSUB_XS_APIVERSION_invalid);
@@ -2750,6 +2770,11 @@ CODE:
     PERL_UNUSED_VAR(items);
     croak("postinc called as a function");
 
+void
+filter()
+CODE:
+    filter_add(filter_call, NULL);
+
 BOOT:
 {
     CV *asscv = get_cv("XS::APItest::postinc", 0);
diff --git a/ext/XS-APItest/t/eval-filter.t b/ext/XS-APItest/t/eval-filter.t
new file mode 100644
index 0000000000..8d370e59a7
--- /dev/null
+++ b/ext/XS-APItest/t/eval-filter.t
@@ -0,0 +1,10 @@
+#!perl -w
+use strict;
+
+use Test::More tests => 1;
+use XS::APItest;
+
+BEGIN { eval "BEGIN{ filter() }" }
+
+is "foo", "fee", "evals share filters with the currently compiling scope";
+# See [perl #87064].