[perl #87064] eval no longer shares filters

Before this commit:

commit f07ec6d
Author: Zefram <zefram@fysh.org>
Date:   Wed Oct 13 19:05:19 2010 +0100

    remove filter inheritance option from lex_start

    The only uses of lex_start that had the new_filter parameter false,
    to make the new lexer context share source filters with the previous
    lexer context, were uses with rsfp null, which therefore never invoked
    source filters.  Inheriting source filters from a logically unrelated
    file seems like a silly idea anyway.

string evals could inherit the same source filter space as the cur-
rently compiling code. Despite what the quoted commit message says,
sharing source filters allows filters to be inherited in both direc-
tions: A source filter created when the eval is being compiled also
applies to the file with which it is sharing its space.

There are at least 20 CPAN distributions relying on this behaviour
(or, rather, what could be considered a Test::More bug). So this com-
mit restores the source-filter-sharing capability. It does not change
the current API or make public the API for sharing source filters, as
this is supposed to be a temporary stop-gap measure for 5.14.

MANIFEST

@@ -3633,6 +3633,7 @@ ext/XS-APItest/t/cleanup.t	test stack behaviour on unwinding
 ext/XS-APItest/t/cophh.t	test COPHH API
 ext/XS-APItest/t/copyhints.t	test hv_copy_hints_hv() API
 ext/XS-APItest/t/customop.t	XS::APItest: tests for custom ops
+ext/XS-APItest/t/eval-filter.t	Simple source filter/eval test
 ext/XS-APItest/t/exception.t	XS::APItest extension
 ext/XS-APItest/t/grok.t		XS::APItest: tests for grok* functions
 ext/XS-APItest/t/hash.t		XS::APItest: tests for hash related APIs

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

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);

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].

op.c

@@ -4453,7 +4453,7 @@ Perl_vload_module(pTHX_ U32 flags, SV *name, SV *ver, va_list *args)
 
     ENTER;
     SAVEVPTR(PL_curcop);
-    lex_start(NULL, NULL, 0);
+    lex_start(NULL, NULL, LEX_START_SAME_FILTER);
     utilize(!(flags & PERL_LOADMOD_DENY), start_subparse(FALSE, 0),
 	    veop, modname, imop);
     LEAVE;

parser.h

@@ -112,6 +112,9 @@ typedef struct yy_parser {
 /* flags for lexer API */
 #define LEX_STUFF_UTF8		0x00000001
 #define LEX_KEEP_PREVIOUS	0x00000002
+#ifdef PERL_CORE
+# define LEX_START_SAME_FILTER	0x00000001
+#endif
 
 /* flags for parser API */
 #define PARSE_OPTIONAL          0x00000001

pp_ctl.c

@@ -3090,7 +3090,7 @@ Perl_sv_compile_2op_is_broken(pTHX_ SV *sv, OP **startop, const char *code,
     PERL_ARGS_ASSERT_SV_COMPILE_2OP_IS_BROKEN;
 
     ENTER_with_name("eval");
-    lex_start(sv, NULL, 0);
+    lex_start(sv, NULL, LEX_START_SAME_FILTER);
     SAVETMPS;
     /* switch to eval mode */
 
@@ -3957,7 +3957,7 @@ PP(pp_entereval)
     TAINT_PROPER("eval");
 
     ENTER_with_name("eval");
-    lex_start(sv, NULL, 0);
+    lex_start(sv, NULL, LEX_START_SAME_FILTER);
     SAVETMPS;
 
     /* switch to eval mode */

toke.c

@@ -667,19 +667,23 @@ code in I<line> comes first and must consist of complete lines of input,
 and I<rsfp> supplies the remainder of the source.
 
 The I<flags> parameter is reserved for future use, and must always
-be zero.
+be zero, except for one flag that is currently reserved for perl's internal
+use.
 
 =cut
 */
 
+/* LEX_START_SAME_FILTER indicates that this is not a new file, so it
+   can share filters with the current parser. */
+
 void
 Perl_lex_start(pTHX_ SV *line, PerlIO *rsfp, U32 flags)
 {
     dVAR;
     const char *s = NULL;
     STRLEN len;
     yy_parser *parser, *oparser;
-    if (flags)
+    if (flags && flags != LEX_START_SAME_FILTER)
 	Perl_croak(aTHX_ "Lexing code internal error (%s)", "lex_start");
 
     /* create and initialise a parser */
@@ -708,7 +712,10 @@ Perl_lex_start(pTHX_ SV *line, PerlIO *rsfp, U32 flags)
     parser->lex_state = LEX_NORMAL;
     parser->expect = XSTATE;
     parser->rsfp = rsfp;
-    parser->rsfp_filters = newAV();
+    parser->rsfp_filters =
+      !(flags & LEX_START_SAME_FILTER) || !oparser
+        ? newAV()
+        : MUTABLE_AV(SvREFCNT_inc(oparser->rsfp_filters));
 
     Newx(parser->lex_brackstack, 120, char);
     Newx(parser->lex_casestack, 12, char);