Integrate from perlio:

[ 18560]
Fixes for open.pm which attempts to load layers:
 1. C equivalent of local $SIG{__WARN__} = sub {} 
    while loading layers to supress warnings lib/open.t does
    not want.
 2. The loading scheme does not recurse now so look for 
    new symptom of bad layer which is that a good module 
    fails to load (as we cannot open any files).

NOTE: In my opinion open.pm should probably die on bad layer
spec rather than just (maybe) warning and then allowing opens
to fail.
p4raw-link: @18560 on //depot/perlio: c9bca74aca217023baf0f921dcffaaa072a83cf3

p4raw-id: //depot/perl@18561

1 files changed, 18 insertions, 1 deletions

diff --git a/perlio.c b/perlio.c
index 79f75d3014..e6de36f29a 100644
--- a/perlio.c
+++ b/perlio.c
@@ -666,8 +666,13 @@ PerlIO_find_layer(pTHX_ const char *name, STRLEN len, int load)
 	} else {
 	    SV *pkgsv = newSVpvn("PerlIO", 6);
 	    SV *layer = newSVpvn(name, len);
-	    ENTER;
+	    CV *cv  = get_cv("PerlIO::Layer::NoWarnings", FALSE);
+    	    ENTER;
 	    SAVEINT(PL_in_load_module);
+	    if (cv) {
+	        SAVESPTR(PL_warnhook);
+		PL_warnhook = (SV *) cv;
+	    }
 	    PL_in_load_module++;
 	    /*
 	     * The two SVs are magically freed by load_module
@@ -770,6 +775,17 @@ PerlIO_tab_sv(pTHX_ PerlIO_funcs *tab)
     return sv;
 }
 
+XS(XS_PerlIO__Layer__NoWarnings)
+{
+    /* This is used as a %SIG{__WARN__} handler to supress warnings 
+       during loading of layers.
+     */
+    dXSARGS;
+    if (items)
+    	PerlIO_debug("warning:%s\n",SvPV_nolen(ST(0)));
+    XSRETURN(0);
+}
+
 XS(XS_PerlIO__Layer__find)
 {
     dXSARGS;
@@ -1012,6 +1028,7 @@ Perl_boot_core_PerlIO(pTHX)
 	  __FILE__);
 #endif
     newXS("PerlIO::Layer::find", XS_PerlIO__Layer__find, __FILE__);
+    newXS("PerlIO::Layer::NoWarnings", XS_PerlIO__Layer__NoWarnings, __FILE__);
 }
 
 PerlIO_funcs *