Add Perl_croak_xs_usage(), which reduces a lot of explicit calls of

the form Perl_croak(aTHX_ "Usage %s::%s(%s)", "ouch" "awk", "eee_yow");
down to croak_xs_usage(cv, "eee_yow"); and refactor all the core XS
code to use it. This adds () to the error messages for attributes::*

p4raw-id: //depot/perl@33901

8 files changed, 115 insertions, 108 deletions

diff --git a/embed.fnc b/embed.fnc
index 43fe830c0f..f08dfef1a5 100644
--- a/embed.fnc
+++ b/embed.fnc
@@ -148,6 +148,9 @@ pM	|PERL_CONTEXT*	|create_eval_scope|U32 flags
 : croak()'s first parm can be NULL.  Otherwise, mod_perl breaks.
 Afprd	|void	|croak		|NULLOK const char* pat|...
 Apr	|void	|vcroak		|NULLOK const char* pat|NULLOK va_list* args
+Aprd	|void	|croak_xs_usage	|NN const CV *const cv \
+				|NN const char *const params
+
 #if defined(PERL_IMPLICIT_CONTEXT)
 Afnrp	|void	|croak_nocontext|NULLOK const char* pat|...
 Afnp	|OP*	|die_nocontext	|NN const char* pat|...
diff --git a/embed.h b/embed.h
index 6d4e489140..9caec1d93d 100644
--- a/embed.h
+++ b/embed.h
@@ -104,6 +104,7 @@
 #endif
 #define croak			Perl_croak
 #define vcroak			Perl_vcroak
+#define croak_xs_usage		Perl_croak_xs_usage
 #if defined(PERL_IMPLICIT_CONTEXT)
 #define croak_nocontext		Perl_croak_nocontext
 #define die_nocontext		Perl_die_nocontext
@@ -2421,6 +2422,7 @@
 #define create_eval_scope(a)	Perl_create_eval_scope(aTHX_ a)
 #endif
 #define vcroak(a,b)		Perl_vcroak(aTHX_ a,b)
+#define croak_xs_usage(a,b)	Perl_croak_xs_usage(aTHX_ a,b)
 #if defined(PERL_IMPLICIT_CONTEXT)
 #endif
 #ifdef PERL_CORE
diff --git a/global.sym b/global.sym
index 53e15a8a5f..248d8a4bb4 100644
--- a/global.sym
+++ b/global.sym
@@ -61,6 +61,7 @@ Perl_cast_uv
 Perl_my_chsize
 Perl_croak
 Perl_vcroak
+Perl_croak_xs_usage
 Perl_croak_nocontext
 Perl_die_nocontext
 Perl_deb_nocontext
diff --git a/mro.c b/mro.c
index 2d52805826..13dd70a15a 100644
--- a/mro.c
+++ b/mro.c
@@ -707,10 +707,8 @@ XS(XS_mro_get_linear_isa) {
     HV* class_stash;
     SV* classname;
 
-    PERL_UNUSED_ARG(cv);
-
     if(items < 1 || items > 2)
-       Perl_croak(aTHX_ "Usage: mro::get_linear_isa(classname [, type ])");
+	croak_xs_usage(cv, "classname [, type ]");
 
     classname = ST(0);
     class_stash = gv_stashsv(classname, 0);
@@ -748,10 +746,8 @@ XS(XS_mro_set_mro)
     HV* class_stash;
     struct mro_meta* meta;
 
-    PERL_UNUSED_ARG(cv);
-
     if (items != 2)
-       Perl_croak(aTHX_ "Usage: mro::set_mro(classname, type)");
+	croak_xs_usage(cv, "classname, type");
 
     classname = ST(0);
     whichstr = SvPV_nolen(ST(1));
@@ -783,10 +779,8 @@ XS(XS_mro_get_mro)
     SV* classname;
     HV* class_stash;
 
-    PERL_UNUSED_ARG(cv);
-
     if (items != 1)
-       Perl_croak(aTHX_ "Usage: mro::get_mro(classname)");
+	croak_xs_usage(cv, "classname");
 
     classname = ST(0);
     class_stash = gv_stashsv(classname, 0);
@@ -806,10 +800,8 @@ XS(XS_mro_get_isarev)
     HV* isarev;
     AV* ret_array;
 
-    PERL_UNUSED_ARG(cv);
-
     if (items != 1)
-       Perl_croak(aTHX_ "Usage: mro::get_isarev(classname)");
+	croak_xs_usage(cv, "classname");
 
     classname = ST(0);
 
@@ -842,10 +834,8 @@ XS(XS_mro_is_universal)
     STRLEN classname_len;
     HE* he;
 
-    PERL_UNUSED_ARG(cv);
-
     if (items != 1)
-       Perl_croak(aTHX_ "Usage: mro::is_universal(classname)");
+	croak_xs_usage(cv, "classname");
 
     classname = ST(0);
 
@@ -866,10 +856,8 @@ XS(XS_mro_invalidate_method_caches)
     dVAR;
     dXSARGS;
 
-    PERL_UNUSED_ARG(cv);
-
     if (items != 0)
-        Perl_croak(aTHX_ "Usage: mro::invalidate_all_method_caches()");
+	croak_xs_usage(cv, "");
 
     PL_sub_generation++;
 
@@ -883,10 +871,8 @@ XS(XS_mro_method_changed_in)
     SV* classname;
     HV* class_stash;
 
-    PERL_UNUSED_ARG(cv);
-
     if(items != 1)
-        Perl_croak(aTHX_ "Usage: mro::method_changed_in(classname)");
+	croak_xs_usage(cv, "classname");
     
     classname = ST(0);
 
@@ -905,10 +891,8 @@ XS(XS_mro_get_pkg_gen)
     SV* classname;
     HV* class_stash;
 
-    PERL_UNUSED_ARG(cv);
-
     if(items != 1)
-        Perl_croak(aTHX_ "Usage: mro::get_pkg_gen(classname)");
+	croak_xs_usage(cv, "classname");
     
     classname = ST(0);
 
diff --git a/pod/perlapi.pod b/pod/perlapi.pod
index 2644e88a8a..effd8fbe0e 100644
--- a/pod/perlapi.pod
+++ b/pod/perlapi.pod
@@ -3931,6 +3931,23 @@ Found in file sv.h
 
 =over 8
 
+=item croak_xs_usage
+X<croak_xs_usage>
+
+A specialised variant of C<croak()> for emitting the usage message for xsubs
+
+    croak_xs_usage(cv, "eee_yow");
+
+works out the package name and subroutine name from C<cv>, and then calls
+C<croak()>. Hence if C<cv> is C<&ouch::awk>, it would call C<croak> as:
+
+    Perl_croak(aTHX_ "Usage %s::%s(%s)", "ouch" "awk", "eee_yow");
+
+	void	croak_xs_usage(CV *const cv, const char *const params)
+
+=for hackers
+Found in file universal.c
+
 =item get_sv
 X<get_sv>
 
diff --git a/proto.h b/proto.h
index e40cdcfaeb..da79be1516 100644
--- a/proto.h
+++ b/proto.h
@@ -327,6 +327,14 @@ PERL_CALLCONV void	Perl_croak(pTHX_ const char* pat, ...)
 PERL_CALLCONV void	Perl_vcroak(pTHX_ const char* pat, va_list* args)
 			__attribute__noreturn__;
 
+PERL_CALLCONV void	Perl_croak_xs_usage(pTHX_ const CV *const cv, const char *const params)
+			__attribute__noreturn__
+			__attribute__nonnull__(pTHX_1)
+			__attribute__nonnull__(pTHX_2);
+#define PERL_ARGS_ASSERT_CROAK_XS_USAGE	\
+	assert(cv); assert(params)
+
+
 #if defined(PERL_IMPLICIT_CONTEXT)
 PERL_CALLCONV void	Perl_croak_nocontext(const char* pat, ...)
 			__attribute__noreturn__
diff --git a/universal.c b/universal.c
index d03596c82b..7026195b6b 100644
--- a/universal.c
+++ b/universal.c
@@ -296,15 +296,50 @@ Perl_boot_core_UNIVERSAL(pTHX)
     newXS("Tie::Hash::NamedCapture::flags", XS_Tie_Hash_NamedCapture_flags, file);
 }
 
+/*
+=for apidoc croak_xs_usage
+
+A specialised variant of C<croak()> for emitting the usage message for xsubs
+
+    croak_xs_usage(cv, "eee_yow");
+
+works out the package name and subroutine name from C<cv>, and then calls
+C<croak()>. Hence if C<cv> is C<&ouch::awk>, it would call C<croak> as:
+
+    Perl_croak(aTHX_ "Usage %s::%s(%s)", "ouch" "awk", "eee_yow");
+
+=cut
+*/
+
+void
+Perl_croak_xs_usage(pTHX_ const CV *const cv, const char *const params)
+{
+    const GV *const gv = CvGV(cv);
+
+    PERL_ARGS_ASSERT_CROAK_XS_USAGE;
+
+    if (gv) {
+	const char *const gvname = GvNAME(gv);
+	const HV *const stash = GvSTASH(gv);
+	const char *const hvname = stash ? HvNAME_get(stash) : NULL;
+
+	if (hvname)
+	    Perl_croak(aTHX_ "Usage: %s::%s(%s)", hvname, gvname, params);
+	else
+	    Perl_croak(aTHX_ "Usage: %s(%s)", gvname, params);
+    } else {
+	/* Pants. I don't think that it should be possible to get here. */
+	Perl_croak(aTHX_ "Usage: CODE(%"UVXf")(%s)", (UV)cv, params);
+    }
+}
 
 XS(XS_UNIVERSAL_isa)
 {
     dVAR;
     dXSARGS;
-    PERL_UNUSED_ARG(cv);
 
     if (items != 2)
-	Perl_croak(aTHX_ "Usage: UNIVERSAL::isa(reference, kind)");
+	croak_xs_usage(cv, "reference, kind");
     else {
 	SV * const sv = ST(0);
 	const char *name;
@@ -330,10 +365,9 @@ XS(XS_UNIVERSAL_can)
     const char *name;
     SV   *rv;
     HV   *pkg = NULL;
-    PERL_UNUSED_ARG(cv);
 
     if (items != 2)
-	Perl_croak(aTHX_ "Usage: UNIVERSAL::can(object-ref, method)");
+	croak_xs_usage(cv, "object-ref, method");
 
     sv = ST(0);
 
@@ -471,9 +505,8 @@ XS(XS_version_new)
 {
     dVAR;
     dXSARGS;
-    PERL_UNUSED_ARG(cv);
     if (items > 3)
-	Perl_croak(aTHX_ "Usage: version::new(class, version)");
+	croak_xs_usage(cv, "class, version");
     SP -= items;
     {
         SV *vs = ST(1);
@@ -507,9 +540,8 @@ XS(XS_version_stringify)
 {
      dVAR;
      dXSARGS;
-     PERL_UNUSED_ARG(cv);
      if (items < 1)
-	  Perl_croak(aTHX_ "Usage: version::stringify(lobj, ...)");
+	 croak_xs_usage(cv, "lobj, ...");
      SP -= items;
      {
 	  SV *	lobj;
@@ -531,9 +563,8 @@ XS(XS_version_numify)
 {
      dVAR;
      dXSARGS;
-     PERL_UNUSED_ARG(cv);
      if (items < 1)
-	  Perl_croak(aTHX_ "Usage: version::numify(lobj, ...)");
+	 croak_xs_usage(cv, "lobj, ...");
      SP -= items;
      {
 	  SV *	lobj;
@@ -555,9 +586,8 @@ XS(XS_version_normal)
 {
      dVAR;
      dXSARGS;
-     PERL_UNUSED_ARG(cv);
      if (items < 1)
-	  Perl_croak(aTHX_ "Usage: version::normal(lobj, ...)");
+	 croak_xs_usage(cv, "lobj, ...");
      SP -= items;
      {
 	  SV *	lobj;
@@ -579,9 +609,8 @@ XS(XS_version_vcmp)
 {
      dVAR;
      dXSARGS;
-     PERL_UNUSED_ARG(cv);
      if (items < 1)
-	  Perl_croak(aTHX_ "Usage: version::vcmp(lobj, ...)");
+	 croak_xs_usage(cv, "lobj, ...");
      SP -= items;
      {
 	  SV *	lobj;
@@ -625,9 +654,8 @@ XS(XS_version_boolean)
 {
     dVAR;
     dXSARGS;
-    PERL_UNUSED_ARG(cv);
     if (items < 1)
-	Perl_croak(aTHX_ "Usage: version::boolean(lobj, ...)");
+	croak_xs_usage(cv, "lobj, ...");
     SP -= items;
     if (sv_derived_from(ST(0), "version")) {
 	SV * const lobj = SvRV(ST(0));
@@ -644,9 +672,8 @@ XS(XS_version_noop)
 {
     dVAR;
     dXSARGS;
-    PERL_UNUSED_ARG(cv);
     if (items < 1)
-	Perl_croak(aTHX_ "Usage: version::noop(lobj, ...)");
+	croak_xs_usage(cv, "lobj, ...");
     if (sv_derived_from(ST(0), "version"))
 	Perl_croak(aTHX_ "operation not supported with version object");
     else
@@ -660,9 +687,8 @@ XS(XS_version_is_alpha)
 {
     dVAR;
     dXSARGS;
-    PERL_UNUSED_ARG(cv);
     if (items != 1)
-	Perl_croak(aTHX_ "Usage: version::is_alpha(lobj)");
+	croak_xs_usage(cv, "lobj");
     SP -= items;
     if (sv_derived_from(ST(0), "version")) {
 	SV * const lobj = ST(0);
@@ -681,9 +707,8 @@ XS(XS_version_qv)
 {
     dVAR;
     dXSARGS;
-    PERL_UNUSED_ARG(cv);
     if (items != 1)
-	Perl_croak(aTHX_ "Usage: version::qv(ver)");
+	croak_xs_usage(cv, "ver");
     SP -= items;
     {
 	SV *	ver = ST(0);
@@ -707,9 +732,8 @@ XS(XS_utf8_is_utf8)
 {
      dVAR;
      dXSARGS;
-     PERL_UNUSED_ARG(cv);
      if (items != 1)
-	  Perl_croak(aTHX_ "Usage: utf8::is_utf8(sv)");
+	 croak_xs_usage(cv, "sv");
      else {
 	const SV * const sv = ST(0);
 	    if (SvUTF8(sv))
@@ -724,9 +748,8 @@ XS(XS_utf8_valid)
 {
      dVAR;
      dXSARGS;
-     PERL_UNUSED_ARG(cv);
      if (items != 1)
-	  Perl_croak(aTHX_ "Usage: utf8::valid(sv)");
+	 croak_xs_usage(cv, "sv");
     else {
 	SV * const sv = ST(0);
 	STRLEN len;
@@ -743,9 +766,8 @@ XS(XS_utf8_encode)
 {
     dVAR;
     dXSARGS;
-    PERL_UNUSED_ARG(cv);
     if (items != 1)
-	Perl_croak(aTHX_ "Usage: utf8::encode(sv)");
+	croak_xs_usage(cv, "sv");
     sv_utf8_encode(ST(0));
     XSRETURN_EMPTY;
 }
@@ -754,9 +776,8 @@ XS(XS_utf8_decode)
 {
     dVAR;
     dXSARGS;
-    PERL_UNUSED_ARG(cv);
     if (items != 1)
-	Perl_croak(aTHX_ "Usage: utf8::decode(sv)");
+	croak_xs_usage(cv, "sv");
     else {
 	SV * const sv = ST(0);
 	const bool RETVAL = sv_utf8_decode(sv);
@@ -770,9 +791,8 @@ XS(XS_utf8_upgrade)
 {
     dVAR;
     dXSARGS;
-    PERL_UNUSED_ARG(cv);
     if (items != 1)
-	Perl_croak(aTHX_ "Usage: utf8::upgrade(sv)");
+	croak_xs_usage(cv, "sv");
     else {
 	SV * const sv = ST(0);
 	STRLEN	RETVAL;
@@ -788,9 +808,8 @@ XS(XS_utf8_downgrade)
 {
     dVAR;
     dXSARGS;
-    PERL_UNUSED_ARG(cv);
     if (items < 1 || items > 2)
-	Perl_croak(aTHX_ "Usage: utf8::downgrade(sv, failok=0)");
+	croak_xs_usage(cv, "sv, failok=0");
     else {
 	SV * const sv = ST(0);
         const bool failok = (items < 2) ? 0 : (int)SvIV(ST(1));
@@ -807,10 +826,9 @@ XS(XS_utf8_native_to_unicode)
  dVAR;
  dXSARGS;
  const UV uv = SvUV(ST(0));
- PERL_UNUSED_ARG(cv);
 
  if (items > 1)
-     Perl_croak(aTHX_ "Usage: utf8::native_to_unicode(sv)");
+     croak_xs_usage(cv, "sv");
 
  ST(0) = sv_2mortal(newSViv(NATIVE_TO_UNI(uv)));
  XSRETURN(1);
@@ -821,10 +839,9 @@ XS(XS_utf8_unicode_to_native)
  dVAR;
  dXSARGS;
  const UV uv = SvUV(ST(0));
- PERL_UNUSED_ARG(cv);
 
  if (items > 1)
-     Perl_croak(aTHX_ "Usage: utf8::unicode_to_native(sv)");
+     croak_xs_usage(cv, "sv");
 
  ST(0) = sv_2mortal(newSViv(UNI_TO_NATIVE(uv)));
  XSRETURN(1);
@@ -878,10 +895,9 @@ XS(XS_Internals_hv_clear_placehold)
 {
     dVAR;
     dXSARGS;
-    PERL_UNUSED_ARG(cv);
 
     if (items != 1)
-	Perl_croak(aTHX_ "Usage: UNIVERSAL::hv_clear_placeholders(hv)");
+	croak_xs_usage(cv, "hv");
     else {
 	HV * const hv = (HV *) SvRV(ST(0));
 	hv_clear_placeholders(hv);
@@ -899,9 +915,8 @@ XS(XS_PerlIO_get_layers)
 {
     dVAR;
     dXSARGS;
-    PERL_UNUSED_ARG(cv);
     if (items < 1 || items % 2 == 0)
-	Perl_croak(aTHX_ "Usage: PerlIO_get_layers(filehandle[,args])");
+	croak_xs_usage(cv, "filehandle[,args]");
 #ifdef USE_PERLIO
     {
 	SV *	sv;
@@ -1050,7 +1065,6 @@ XS(XS_Internals_HvREHASH)	/* Subject to change  */
 {
     dVAR;
     dXSARGS;
-    PERL_UNUSED_ARG(cv);
     if (SvROK(ST(0))) {
 	const HV * const hv = (HV *) SvRV(ST(0));
 	if (items == 1 && SvTYPE(hv) == SVt_PVHV) {
@@ -1070,7 +1084,7 @@ XS(XS_re_is_regexp)
     PERL_UNUSED_VAR(cv);
 
     if (items != 1)
-       Perl_croak(aTHX_ "Usage: %s(%s)", "re::is_regexp", "sv");
+	croak_xs_usage(cv, "sv");
 
     SP -= items;
 
@@ -1087,10 +1101,9 @@ XS(XS_re_regnames_count)
     SV * ret;
     dVAR; 
     dXSARGS;
-    PERL_UNUSED_ARG(cv);
 
     if (items != 0)
-       Perl_croak(aTHX_ "Usage: %s(%s)", "re::regnames_count", "");
+	croak_xs_usage(cv, "");
 
     SP -= items;
 
@@ -1117,10 +1130,9 @@ XS(XS_re_regname)
     REGEXP * rx;
     U32 flags;
     SV * ret;
-    PERL_UNUSED_ARG(cv);
 
     if (items < 1 || items > 2)
-        Perl_croak(aTHX_ "Usage: %s(%s)", "re::regname", "name[, all ]");
+	croak_xs_usage(cv, "name[, all ]");
 
     SP -= items;
 
@@ -1158,10 +1170,9 @@ XS(XS_re_regnames)
     I32 length;
     I32 i;
     SV **entry;
-    PERL_UNUSED_ARG(cv);
 
     if (items > 1)
-        Perl_croak(aTHX_ "Usage: %s(%s)", "re::regnames", "[all]");
+	croak_xs_usage(cv, "[all]");
 
     rx = PL_curpm ? PM_GETRE(PL_curpm) : NULL;
 
@@ -1205,10 +1216,9 @@ XS(XS_re_regexp_pattern)
     dVAR;
     dXSARGS;
     REGEXP *re;
-    PERL_UNUSED_ARG(cv);
 
     if (items != 1)
-       Perl_croak(aTHX_ "Usage: %s(%s)", "re::regexp_pattern", "sv");
+	croak_xs_usage(cv, "sv");
 
     SP -= items;
 
@@ -1298,10 +1308,9 @@ XS(XS_Tie_Hash_NamedCapture_FETCH)
     REGEXP * rx;
     U32 flags;
     SV * ret;
-    PERL_UNUSED_ARG(cv);
 
     if (items != 2)
-        Perl_croak(aTHX_ "Usage: Tie::Hash::NamedCapture::STORE($key, $flags)");
+	croak_xs_usage(cv, "$key, $flags");
 
     rx = PL_curpm ? PM_GETRE(PL_curpm) : NULL;
 
@@ -1332,10 +1341,9 @@ XS(XS_Tie_Hash_NamedCapture_STORE)
     dXSARGS;
     REGEXP * rx;
     U32 flags;
-    PERL_UNUSED_ARG(cv);
 
     if (items != 3)
-        Perl_croak(aTHX_ "Usage: Tie::Hash::NamedCapture::STORE($key, $value, $flags)");
+	croak_xs_usage(cv, "$key, $value, $flags");
 
     rx = PL_curpm ? PM_GETRE(PL_curpm) : NULL;
 
@@ -1358,10 +1366,9 @@ XS(XS_Tie_Hash_NamedCapture_DELETE)
     dXSARGS;
     REGEXP * rx = PL_curpm ? PM_GETRE(PL_curpm) : NULL;
     U32 flags;
-    PERL_UNUSED_ARG(cv);
 
     if (items != 2)
-        Perl_croak(aTHX_ "Usage: Tie::Hash::NamedCapture::DELETE($key, $flags)");
+	croak_xs_usage(cv, "$key, $flags");
 
     if (!rx)
         Perl_croak(aTHX_ PL_no_modify);
@@ -1378,10 +1385,9 @@ XS(XS_Tie_Hash_NamedCapture_CLEAR)
     dXSARGS;
     REGEXP * rx;
     U32 flags;
-    PERL_UNUSED_ARG(cv);
 
     if (items != 1)
-        Perl_croak(aTHX_ "Usage: Tie::Hash::NamedCapture::CLEAR($flags)");
+	croak_xs_usage(cv, "$flags");
 
     rx = PL_curpm ? PM_GETRE(PL_curpm) : NULL;
 
@@ -1401,10 +1407,9 @@ XS(XS_Tie_Hash_NamedCapture_EXISTS)
     REGEXP * rx;
     U32 flags;
     SV * ret;
-    PERL_UNUSED_ARG(cv);
 
     if (items != 2)
-        Perl_croak(aTHX_ "Usage: Tie::Hash::NamedCapture::EXISTS($key, $flags)");
+	croak_xs_usage(cv, "$key, $flags");
 
     rx = PL_curpm ? PM_GETRE(PL_curpm) : NULL;
 
@@ -1430,10 +1435,9 @@ XS(XS_Tie_Hash_NamedCapture_FIRSTK)
     REGEXP * rx;
     U32 flags;
     SV * ret;
-    PERL_UNUSED_ARG(cv);
 
     if (items != 1)
-        Perl_croak(aTHX_ "Usage: Tie::Hash::NamedCapture::FIRSTKEY()");
+	croak_xs_usage(cv, "");
 
     rx = PL_curpm ? PM_GETRE(PL_curpm) : NULL;
 
@@ -1463,10 +1467,9 @@ XS(XS_Tie_Hash_NamedCapture_NEXTK)
     REGEXP * rx;
     U32 flags;
     SV * ret;
-    PERL_UNUSED_ARG(cv);
 
     if (items != 2)
-        Perl_croak(aTHX_ "Usage: Tie::Hash::NamedCapture::NEXTKEY($lastkey)");
+	croak_xs_usage(cv, "$lastkey");
 
     rx = PL_curpm ? PM_GETRE(PL_curpm) : NULL;
 
@@ -1495,10 +1498,9 @@ XS(XS_Tie_Hash_NamedCapture_SCALAR)
     REGEXP * rx;
     U32 flags;
     SV * ret;
-    PERL_UNUSED_ARG(cv);
 
     if (items != 1)
-        Perl_croak(aTHX_ "Usage: Tie::Hash::NamedCapture::SCALAR()");
+	croak_xs_usage(cv, "");
 
     rx = PL_curpm ? PM_GETRE(PL_curpm) : NULL;
 
@@ -1525,10 +1527,9 @@ XS(XS_Tie_Hash_NamedCapture_flags)
 {
     dVAR;
     dXSARGS;
-    PERL_UNUSED_ARG(cv);
 
     if (items != 0)
-        Perl_croak(aTHX_ "Usage: Tie::Hash::NamedCapture::flags()");
+	croak_xs_usage(cv, "");
 
 	mXPUSHu(RXapif_ONE);
 	mXPUSHu(RXapif_ALL);
diff --git a/xsutils.c b/xsutils.c
index 583527a35f..dcc8d09d8d 100644
--- a/xsutils.c
+++ b/xsutils.c
@@ -150,10 +150,9 @@ XS(XS_attributes_bootstrap)
 {
     dVAR;
     dXSARGS;
-    PERL_UNUSED_ARG(cv);
 
     if( items > 1 )
-        Perl_croak(aTHX_ "Usage: attributes::bootstrap $module");
+	croak_xs_usage(cv, "$module");
 
     newXS("attributes::_modify_attrs",	XS_attributes__modify_attrs,	file);
     newXSproto("attributes::_guess_stash", XS_attributes__guess_stash, file, "$");
@@ -168,12 +167,10 @@ XS(XS_attributes__modify_attrs)
     dVAR;
     dXSARGS;
     SV *rv, *sv;
-    PERL_UNUSED_ARG(cv);
 
     if (items < 1) {
 usage:
-	Perl_croak(aTHX_
-		   "Usage: attributes::_modify_attrs $reference, @attributes");
+	croak_xs_usage(cv, "@attributes");
     }
 
     rv = ST(0);
@@ -192,12 +189,10 @@ XS(XS_attributes__fetch_attrs)
     dXSARGS;
     SV *rv, *sv;
     cv_flags_t cvflags;
-    PERL_UNUSED_ARG(cv);
 
     if (items != 1) {
 usage:
-	Perl_croak(aTHX_
-		   "Usage: attributes::_fetch_attrs $reference");
+	croak_xs_usage(cv, "$reference");
     }
 
     rv = ST(0);
@@ -237,12 +232,10 @@ XS(XS_attributes__guess_stash)
     dXSARGS;
     SV *rv, *sv;
     dXSTARG;
-    PERL_UNUSED_ARG(cv);
 
     if (items != 1) {
 usage:
-	Perl_croak(aTHX_
-		   "Usage: attributes::_guess_stash $reference");
+	croak_xs_usage(cv, "$reference");
     }
 
     rv = ST(0);
@@ -287,12 +280,10 @@ XS(XS_attributes_reftype)
     dXSARGS;
     SV *rv, *sv;
     dXSTARG;
-    PERL_UNUSED_ARG(cv);
 
     if (items != 1) {
 usage:
-	Perl_croak(aTHX_
-		   "Usage: attributes::reftype $reference");
+	croak_xs_usage(cv, "$reference");
     }
 
     rv = ST(0);