+/*
+=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(0x%"UVxf")(%s)", PTR2UV(cv), params);
+ }
+}