[inseparable changes from match from perl-5.003_97a to perl-5.003_97b]

 BUILD PROCESS

Subject: Don't suggest 'Configure -der' in config.sh comments
From: Chip Salzenberg <chip@perl.com>
Files: Configure

 CORE LANGUAGE CHANGES

Subject: Make assignment to C<$)> call setgroups()
From: Chip Salzenberg <chip@perl.com>
Files: Configure config_H config_h.SH mg.c plan9/config.plan9 pod/perldelta.pod vms/config.vms win32/config.H win32/config.w32

Subject: Grandfather "$$<digit>" in strings
From: Chip Salzenberg <chip@perl.com>
Files: pod/perldiag.pod toke.c

Subject: Disconnect warn and die hooks _after_ object destruction
From: Chip Salzenberg <chip@perl.com>
Files: perl.c

Subject: Forbid recursive substitutions
From: Chip Salzenberg <chip@perl.com>
Files: cop.h pod/perldelta.pod pod/perldiag.pod pp_ctl.c pp_hot.c

 DOCUMENTATION

Subject: Document required module versions
From: Chip Salzenberg <chip@perl.com>
Files: pod/perldelta.pod

 LIBRARY AND EXTENSIONS

Subject: Updates to Math::Complex and Math::Trig
From: Jarkko Hietaniemi <Jarkko.Hietaniemi@cc.hut.fi>
Files: lib/Math/Complex.pm lib/Math/Trig.pm pod/perldelta.pod t/lib/complex.t

 OTHER CORE CHANGES

Subject: length($') isn't
Date: Mon, 07 Apr 1997 03:30:44 -0400
From: Gurusamy Sarathy <gsar@engin.umich.edu>
Files: mg.c
Msg-ID: 199704070730.DAA07310@aatma.engin.umich.edu

    (applied based on p5p patch as commit 645a7cbb1f14932f058231f0a4f808b88ebe8703)

Subject: Fix obscure regex bug related to leading C<.*>
From: Chip Salzenberg <chip@perl.com>
Files: toke.c

Subject: Add warning for glob failure
From: Chip Salzenberg <chip@perl.com>
Files: pod/perldelta.pod pod/perldiag.pod pp_hot.c

Subject: Fix C<perl -V> in presence of local patches
From: Chip Salzenberg <chip@perl.com>
Files: perl.c

1 files changed, 22 insertions, 8 deletions

diff --git a/pp_hot.c b/pp_hot.c
index 2f735a3bf6..0422017d74 100644
--- a/pp_hot.c
+++ b/pp_hot.c
@@ -1171,7 +1171,8 @@ do_readline()
 		IoFLAGS(io) |= IOf_START;
 	    }
 	    else if (type == OP_GLOB) {
-		(void)do_close(last_in_gv, FALSE);
+		if (do_close(last_in_gv, FALSE) & ~0xFF)
+		    warn("internal error: glob failed");
 	    }
 	    if (gimme == G_SCALAR) {
 		(void)SvOK_off(TARG);
@@ -1386,6 +1387,13 @@ PP(pp_iter)
     RETPUSHYES;
 }
 
+static void
+leave_subst(p)
+void *p;
+{
+    ((PMOP*)p)->op_private &= ~OPpLVAL_INTRO;
+}
+
 PP(pp_subst)
 {
     dSP; dTARG;
@@ -1410,8 +1418,8 @@ PP(pp_subst)
     int force_on_match = 0;
     I32 oldsave = savestack_ix;
 
-    if (pm->op_pmflags & PMf_CONST)	/* known replacement string? */
-	dstr = POPs;
+    /* known replacement string? */
+    dstr = (pm->op_pmflags & PMf_CONST) ? POPs : Nullsv;
     if (op->op_flags & OPf_STACKED)
 	TARG = POPs;
     else {
@@ -1427,6 +1435,13 @@ PP(pp_subst)
 	force_on_match = 1;
     TAINT_NOT;
 
+    if (pm->op_private & OPpLVAL_INTRO)
+	croak("Recursive substitution detected");
+    if (!dstr) {
+	SAVEDESTRUCTOR(leave_subst, pm);
+	pm->op_private |= OPpLVAL_INTRO;
+    }
+
   force_it:
     if (!pm || !s)
 	DIE("panic: do_subst");
@@ -1480,7 +1495,7 @@ PP(pp_subst)
     once = !(rpm->op_pmflags & PMf_GLOBAL);
 
     /* known replacement string? */
-    c = (rpm->op_pmflags & PMf_CONST) ? SvPV(dstr, clen) : Nullch;
+    c = dstr ? SvPV(dstr, clen) : Nullch;
 
     /* can do inplace substitution? */
     if (c && clen <= rx->minlen) {
@@ -1630,13 +1645,12 @@ PP(pp_subst)
 	LEAVE_SCOPE(oldsave);
 	RETURN;
     }
-
-    PUSHs(&sv_no);
-    LEAVE_SCOPE(oldsave);
-    RETURN;
+    goto ret_no;
 
 nope:
     ++BmUSEFUL(pm->op_pmshort);
+
+ret_no:
     PUSHs(&sv_no);
     LEAVE_SCOPE(oldsave);
     RETURN;