add strbeg argument to Perl_re_intuit_start()

(note that this is a change both to the perl API and the regex engine
plugin API).

Currently, Perl_re_intuit_start() is passed an SV, plus pointers to:
where in the string to start matching (strpos); and to the end of the
string (strend).

Unlike Perl_regexec_flags(), it doesn't also have a strbeg arg.
Because of this this, it guesses strbeg: based on the passed SV (if its
svPOK()); or just set to strpos otherwise. This latter can happen if for
example the SV is overloaded. Note also that this latter guess is wrong,
and could in theory make /\b.../ fail.

But just to confuse matters, although Perl_re_intuit_start() itself uses
its guesstimate strbeg var, some of the functions it calls use the global
value of PL_bostr instead. To make this work, the *callers* of
Perl_re_intuit_start() currently set PL_bostr first. This is why \b
doesn't actually break.

The fix to this unholy mess is to simply add a strbeg arg to
Perl_re_intuit_start(). It's also the first step to eliminating PL_bostr
altogether.

2 files changed, 10 insertions, 4 deletions

diff --git a/ext/re/re.pm b/ext/re/re.pm
index 6e9e9b0f29..ebad00a66a 100644
--- a/ext/re/re.pm
+++ b/ext/re/re.pm
@@ -4,7 +4,7 @@ package re;
 use strict;
 use warnings;
 
-our $VERSION     = "0.24";
+our $VERSION     = "0.25";
 our @ISA         = qw(Exporter);
 our @EXPORT_OK   = ('regmust',
                     qw(is_regexp regexp_pattern
diff --git a/ext/re/re.xs b/ext/re/re.xs
index 1da68f12ee..93a3b9cac1 100644
--- a/ext/re/re.xs
+++ b/ext/re/re.xs
@@ -20,9 +20,15 @@ extern I32	my_regexec (pTHX_ REGEXP * const prog, char* stringarg, char* strend,
 			    char* strbeg, I32 minend, SV* screamer,
 			    void* data, U32 flags);
 
-extern char*	my_re_intuit_start (pTHX_ REGEXP * const prog, SV *sv, char *strpos,
-				    char *strend, const U32 flags,
-				    struct re_scream_pos_data_s *data);
+extern char*	my_re_intuit_start(pTHX_
+                    REGEXP * const rx,
+                    SV *sv,
+                    const char * const strbeg,
+                    char *strpos,
+                    char *strend,
+                    const U32 flags,
+                    re_scream_pos_data *data);
+
 extern SV*	my_re_intuit_string (pTHX_ REGEXP * const prog);
 
 extern void	my_regfree (pTHX_ REGEXP * const r);