assert() that every NN argument is not NULL. Otherwise we have the

ability to create landmines that will explode under someone in the
future when they upgrade their compiler to one with better
optimisation. We've already done this at least twice.
(Yes, some of the assertions are after code that would already have
SEGVd because it already deferences a pointer, but they are put in
to make it easier to automate checking that each and every case is
covered.)
Add a tool, checkARGS_ASSERT.pl, to check that every case is covered.

p4raw-id: //depot/perl@33291

1 files changed, 120 insertions, 1 deletions

diff --git a/util.c b/util.c
index c2604e4492..b7e1cce4d7 100644
--- a/util.c
+++ b/util.c
@@ -362,6 +362,8 @@ Perl_delimcpy(pTHX_ register char *to, register const char *toend, register cons
     register I32 tolen;
     PERL_UNUSED_CONTEXT;
 
+    PERL_ARGS_ASSERT_DELIMCPY;
+
     for (tolen = 0; from < fromend; from++, tolen++) {
 	if (*from == '\\') {
 	    if (from[1] != delim) {
@@ -391,6 +393,8 @@ Perl_instr(pTHX_ register const char *big, register const char *little)
     register I32 first;
     PERL_UNUSED_CONTEXT;
 
+    PERL_ARGS_ASSERT_INSTR;
+
     if (!little)
 	return (char*)big;
     first = *little++;
@@ -421,6 +425,7 @@ Perl_instr(pTHX_ register const char *big, register const char *little)
 char *
 Perl_ninstr(pTHX_ const char *big, const char *bigend, const char *little, const char *lend)
 {
+    PERL_ARGS_ASSERT_NINSTR;
     PERL_UNUSED_CONTEXT;
     if (little >= lend)
         return (char*)big;
@@ -452,6 +457,8 @@ Perl_rninstr(pTHX_ register const char *big, const char *bigend, const char *lit
     register const char * const littleend = lend;
     PERL_UNUSED_CONTEXT;
 
+    PERL_ARGS_ASSERT_RNINSTR;
+
     if (little >= littleend)
 	return (char*)bigend;
     bigbeg = big;
@@ -501,6 +508,8 @@ Perl_fbm_compile(pTHX_ SV *sv, U32 flags)
     U32 rarest = 0;
     U32 frequency = 256;
 
+    PERL_ARGS_ASSERT_FBM_COMPILE;
+
     if (flags & FBMcf_TAIL) {
 	MAGIC * const mg = SvUTF8(sv) && SvMAGICAL(sv) ? mg_find(sv, PERL_MAGIC_utf8) : NULL;
 	sv_catpvs(sv, "\n");		/* Taken into account in fbm_instr() */
@@ -578,6 +587,8 @@ Perl_fbm_instr(pTHX_ unsigned char *big, register unsigned char *bigend, SV *lit
     register STRLEN littlelen = l;
     register const I32 multiline = flags & FBMrf_MULTILINE;
 
+    PERL_ARGS_ASSERT_FBM_INSTR;
+
     if ((STRLEN)(bigend - big) < littlelen) {
 	if ( SvTAIL(littlestr)
 	     && ((STRLEN)(bigend - big) == littlelen - 1)
@@ -781,6 +792,8 @@ Perl_screaminstr(pTHX_ SV *bigstr, SV *littlestr, I32 start_shift, I32 end_shift
     register const unsigned char *littleend;
     I32 found = 0;
 
+    PERL_ARGS_ASSERT_SCREAMINSTR;
+
     assert(SvTYPE(littlestr) == SVt_PVGV);
     assert(SvVALID(littlestr));
 
@@ -864,6 +877,8 @@ Perl_ibcmp(pTHX_ const char *s1, const char *s2, register I32 len)
     register const U8 *b = (const U8 *)s2;
     PERL_UNUSED_CONTEXT;
 
+    PERL_ARGS_ASSERT_IBCMP;
+
     while (len--) {
 	if (*a != *b && *a != PL_fold[*b])
 	    return 1;
@@ -880,6 +895,8 @@ Perl_ibcmp_locale(pTHX_ const char *s1, const char *s2, register I32 len)
     register const U8 *b = (const U8 *)s2;
     PERL_UNUSED_CONTEXT;
 
+    PERL_ARGS_ASSERT_IBCMP_LOCALE;
+
     while (len--) {
 	if (*a != *b && *a != PL_fold_locale[*b])
 	    return 1;
@@ -985,7 +1002,9 @@ char *
 Perl_savesharedpvn(pTHX_ const char *const pv, const STRLEN len)
 {
     char *const newaddr = (char*)PerlMemShared_malloc(len + 1);
-    assert(pv);
+
+    PERL_ARGS_ASSERT_SAVESHAREDPVN;
+
     if (!newaddr) {
 	return write_no_mem();
     }
@@ -1009,6 +1028,8 @@ Perl_savesvpv(pTHX_ SV *sv)
     const char * const pv = SvPV_const(sv, len);
     register char *newaddr;
 
+    PERL_ARGS_ASSERT_SAVESVPV;
+
     ++len;
     Newx(newaddr,len,char);
     return (char *) CopyD(pv,newaddr,len,char);
@@ -1048,6 +1069,7 @@ Perl_form_nocontext(const char* pat, ...)
     dTHX;
     char *retval;
     va_list args;
+    PERL_ARGS_ASSERT_FORM_NOCONTEXT;
     va_start(args, pat);
     retval = vform(pat, &args);
     va_end(args);
@@ -1080,6 +1102,7 @@ Perl_form(pTHX_ const char* pat, ...)
 {
     char *retval;
     va_list args;
+    PERL_ARGS_ASSERT_FORM;
     va_start(args, pat);
     retval = vform(pat, &args);
     va_end(args);
@@ -1090,6 +1113,7 @@ char *
 Perl_vform(pTHX_ const char *pat, va_list *args)
 {
     SV * const sv = mess_alloc();
+    PERL_ARGS_ASSERT_VFORM;
     sv_vsetpvfn(sv, pat, strlen(pat), args, NULL, 0, NULL);
     return SvPVX(sv);
 }
@@ -1101,6 +1125,7 @@ Perl_mess_nocontext(const char *pat, ...)
     dTHX;
     SV *retval;
     va_list args;
+    PERL_ARGS_ASSERT_MESS_NOCONTEXT;
     va_start(args, pat);
     retval = vmess(pat, &args);
     va_end(args);
@@ -1113,6 +1138,7 @@ Perl_mess(pTHX_ const char *pat, ...)
 {
     SV *retval;
     va_list args;
+    PERL_ARGS_ASSERT_MESS;
     va_start(args, pat);
     retval = vmess(pat, &args);
     va_end(args);
@@ -1125,6 +1151,8 @@ S_closest_cop(pTHX_ const COP *cop, const OP *o)
     dVAR;
     /* Look for PL_op starting from o.  cop is the last COP we've seen. */
 
+    PERL_ARGS_ASSERT_CLOSEST_COP;
+
     if (!o || o == PL_op)
 	return cop;
 
@@ -1158,6 +1186,8 @@ Perl_vmess(pTHX_ const char *pat, va_list *args)
     dVAR;
     SV * const sv = mess_alloc();
 
+    PERL_ARGS_ASSERT_VMESS;
+
     sv_vsetpvfn(sv, pat, strlen(pat), args, NULL, 0, NULL);
     if (!SvCUR(sv) || *(SvEND(sv) - 1) != '\n') {
 	/*
@@ -1199,6 +1229,8 @@ Perl_write_to_stderr(pTHX_ const char* message, int msglen)
     IO *io;
     MAGIC *mg;
 
+    PERL_ARGS_ASSERT_WRITE_TO_STDERR;
+
     if (PL_stderrgv && SvREFCNT(PL_stderrgv) 
 	&& (io = GvIO(PL_stderrgv))
 	&& (mg = SvTIED_mg((SV*)io, PERL_MAGIC_tiedscalar))) 
@@ -1353,6 +1385,7 @@ Perl_die_nocontext(const char* pat, ...)
     dTHX;
     OP *o;
     va_list args;
+    PERL_ARGS_ASSERT_DIE_NOCONTEXT;
     va_start(args, pat);
     o = vdie(pat, &args);
     va_end(args);
@@ -1399,6 +1432,7 @@ Perl_croak_nocontext(const char *pat, ...)
 {
     dTHX;
     va_list args;
+    PERL_ARGS_ASSERT_CROAK_NOCONTEXT;
     va_start(args, pat);
     vcroak(pat, &args);
     /* NOTREACHED */
@@ -1445,6 +1479,8 @@ Perl_vwarn(pTHX_ const char* pat, va_list *args)
     const I32 utf8 = SvUTF8(msv);
     const char * const message = SvPV_const(msv, msglen);
 
+    PERL_ARGS_ASSERT_VWARN;
+
     if (PL_warnhook) {
 	if (vdie_common(message, msglen, utf8, TRUE))
 	    return;
@@ -1459,6 +1495,7 @@ Perl_warn_nocontext(const char *pat, ...)
 {
     dTHX;
     va_list args;
+    PERL_ARGS_ASSERT_WARN_NOCONTEXT;
     va_start(args, pat);
     vwarn(pat, &args);
     va_end(args);
@@ -1478,6 +1515,7 @@ void
 Perl_warn(pTHX_ const char *pat, ...)
 {
     va_list args;
+    PERL_ARGS_ASSERT_WARN;
     va_start(args, pat);
     vwarn(pat, &args);
     va_end(args);
@@ -1489,6 +1527,7 @@ Perl_warner_nocontext(U32 err, const char *pat, ...)
 {
     dTHX; 
     va_list args;
+    PERL_ARGS_ASSERT_WARNER_NOCONTEXT;
     va_start(args, pat);
     vwarner(err, pat, &args);
     va_end(args);
@@ -1499,6 +1538,7 @@ void
 Perl_warner(pTHX_ U32  err, const char* pat,...)
 {
     va_list args;
+    PERL_ARGS_ASSERT_WARNER;
     va_start(args, pat);
     vwarner(err, pat, &args);
     va_end(args);
@@ -1508,6 +1548,7 @@ void
 Perl_vwarner(pTHX_ U32  err, const char* pat, va_list* args)
 {
     dVAR;
+    PERL_ARGS_ASSERT_VWARNER;
     if (PL_warnhook == PERL_WARNHOOK_FATAL || ckDEAD(err)) {
 	SV * const msv = vmess(pat, args);
 	STRLEN msglen;
@@ -1589,6 +1630,7 @@ Perl_new_warnings_bitfield(pTHX_ STRLEN *buffer, const char *const bits,
 			   STRLEN size) {
     const MEM_SIZE len_wanted = sizeof(STRLEN) + size;
     PERL_UNUSED_CONTEXT;
+    PERL_ARGS_ASSERT_NEW_WARNINGS_BITFIELD;
 
     buffer = (STRLEN*)
 	(specialWARN(buffer) ?
@@ -1736,6 +1778,8 @@ Perl_setenv_getix(pTHX_ const char *nam)
 {
     register I32 i;
     register const I32 len = strlen(nam);
+
+    PERL_ARGS_ASSERT_SETENV_GETIX;
     PERL_UNUSED_CONTEXT;
 
     for (i = 0; environ[i]; i++) {
@@ -1760,6 +1804,8 @@ Perl_unlnk(pTHX_ const char *f)	/* unlink all versions of a file */
 {
     I32 retries = 0;
 
+    PERL_ARGS_ASSERT_UNLNK;
+
     while (PerlLIO_unlink(f) >= 0)
 	retries++;
     return retries ? 0 : -1;
@@ -1773,6 +1819,8 @@ Perl_my_bcopy(register const char *from,register char *to,register I32 len)
 {
     char * const retval = to;
 
+    PERL_ARGS_ASSERT_MY_BCOPY;
+
     if (from - to >= 0) {
 	while (len--)
 	    *to++ = *from++;
@@ -1794,6 +1842,8 @@ Perl_my_memset(register char *loc, register I32 ch, register I32 len)
 {
     char * const retval = loc;
 
+    PERL_ARGS_ASSERT_MY_MEMSET;
+
     while (len--)
 	*loc++ = ch;
     return retval;
@@ -1807,6 +1857,8 @@ Perl_my_bzero(register char *loc, register I32 len)
 {
     char * const retval = loc;
 
+    PERL_ARGS_ASSERT_MY_BZERO;
+
     while (len--)
 	*loc++ = 0;
     return retval;
@@ -1822,6 +1874,8 @@ Perl_my_memcmp(const char *s1, const char *s2, register I32 len)
     register const U8 *b = (const U8 *)s2;
     register I32 tmp;
 
+    PERL_ARGS_ASSERT_MY_MEMCMP;
+
     while (len--) {
         if ((tmp = *a++ - *b++))
 	    return tmp;
@@ -2205,6 +2259,8 @@ Perl_my_swabn(void *ptr, int n)
     register char *e = s + (n-1);
     register char tc;
 
+    PERL_ARGS_ASSERT_MY_SWABN;
+
     for (n /= 2; n > 0; s++, e--, n--) {
       tc = *s;
       *s = *e;
@@ -2224,6 +2280,8 @@ Perl_my_popen_list(pTHX_ const char *mode, int n, SV **args)
     I32 did_pipes = 0;
     int pp[2];
 
+    PERL_ARGS_ASSERT_MY_POPEN_LIST;
+
     PERL_FLUSHALL_FOR_CHILD;
     This = (*mode == 'w');
     that = !This;
@@ -2364,6 +2422,8 @@ Perl_my_popen(pTHX_ const char *cmd, const char *mode)
     I32 did_pipes = 0;
     int pp[2];
 
+    PERL_ARGS_ASSERT_MY_POPEN;
+
     PERL_FLUSHALL_FOR_CHILD;
 #ifdef OS2
     if (doexec) {
@@ -2512,6 +2572,7 @@ FILE *popen();
 PerlIO *
 Perl_my_popen(pTHX_ const char *cmd, const char *mode)
 {
+    PERL_ARGS_ASSERT_MY_POPEN;
     PERL_FLUSHALL_FOR_CHILD;
     /* Call system's popen() to get a FILE *, then import it.
        used 0 for 2nd parameter to PerlIO_importFILE;
@@ -2602,6 +2663,8 @@ Perl_dump_fds(pTHX_ const char *const s)
     int fd;
     Stat_t tmpstatbuf;
 
+    PERL_ARGS_ASSERT_DUMP_FDS;
+
     PerlIO_printf(Perl_debug_log,"%s", s);
     for (fd = 0; fd < 32; fd++) {
 	if (PerlLIO_fstat(fd,&tmpstatbuf) >= 0)
@@ -2701,6 +2764,8 @@ Perl_rsignal_save(pTHX_ int signo, Sighandler_t handler, Sigsave_t *save)
     dVAR;
     struct sigaction act;
 
+    PERL_ARGS_ASSERT_RSIGNAL_SAVE;
+
 #ifdef USE_ITHREADS
     /* only "parent" interpreter can diddle signals */
     if (PL_curinterp != aTHX)
@@ -2873,6 +2938,7 @@ Perl_wait4pid(pTHX_ Pid_t pid, int *statusp, int flags)
 {
     dVAR;
     I32 result = 0;
+    PERL_ARGS_ASSERT_WAIT4PID;
     if (!pid)
 	return -1;
 #ifdef PERL_USES_PL_PIDSTATUS
@@ -3003,6 +3069,8 @@ Perl_repeatcpy(pTHX_ register char *to, register const char *from, I32 len, regi
     register const char * const frombase = from;
     PERL_UNUSED_CONTEXT;
 
+    PERL_ARGS_ASSERT_REPEATCPY;
+
     if (len == 1) {
 	register const char c = *from;
 	while (count-- > 0)
@@ -3027,6 +3095,8 @@ Perl_same_dirent(pTHX_ const char *a, const char *b)
     Stat_t tmpstatbuf2;
     SV * const tmpsv = sv_newmortal();
 
+    PERL_ARGS_ASSERT_SAME_DIRENT;
+
     if (fa)
 	fa++;
     else
@@ -3089,6 +3159,8 @@ Perl_find_script(pTHX_ const char *scriptname, bool dosearch,
 #  define MAX_EXT_LEN 0
 #endif
 
+    PERL_ARGS_ASSERT_FIND_SCRIPT;
+
     /*
      * If dosearch is true and if scriptname does not contain path
      * delimiters, search the PATH for scriptname.
@@ -3317,6 +3389,7 @@ void
 Perl_set_context(void *t)
 {
     dVAR;
+    PERL_ARGS_ASSERT_SET_CONTEXT;
 #if defined(USE_ITHREADS)
 #  ifdef I_MACH_CTHREADS
     cthread_set_data(cthread_self(), t);
@@ -3381,6 +3454,7 @@ Perl_getenv_len(pTHX_ const char *env_elem, unsigned long *len)
 {
     char * const env_trans = PerlEnv_getenv(env_elem);
     PERL_UNUSED_CONTEXT;
+    PERL_ARGS_ASSERT_GETENV_LEN;
     if (env_trans)
 	*len = strlen(env_trans);
     return env_trans;
@@ -3678,11 +3752,13 @@ Perl_init_tm(pTHX_ struct tm *ptm)	/* see mktime, strftime and asctime */
 #ifdef HAS_TM_TM_ZONE
     Time_t now;
     const struct tm* my_tm;
+    PERL_ARGS_ASSERT_INIT_TM;
     (void)time(&now);
     my_tm = localtime(&now);
     if (my_tm)
         Copy(my_tm, ptm, 1, struct tm);
 #else
+    PERL_ARGS_ASSERT_INIT_TM;
     PERL_UNUSED_ARG(ptm);
 #endif
 }
@@ -3700,6 +3776,8 @@ Perl_mini_mktime(pTHX_ struct tm *ptm)
     int odd_cent, odd_year;
     PERL_UNUSED_CONTEXT;
 
+    PERL_ARGS_ASSERT_MINI_MKTIME;
+
 #define	DAYS_PER_YEAR	365
 #define	DAYS_PER_QYEAR	(4*DAYS_PER_YEAR+1)
 #define	DAYS_PER_CENT	(25*DAYS_PER_QYEAR-1)
@@ -3894,6 +3972,8 @@ Perl_my_strftime(pTHX_ const char *fmt, int sec, int min, int hour, int mday, in
   struct tm mytm;
   int len;
 
+  PERL_ARGS_ASSERT_MY_STRFTIME;
+
   init_tm(&mytm);	/* XXX workaround - see init_tm() above */
   mytm.tm_sec = sec;
   mytm.tm_min = min;
@@ -4001,6 +4081,8 @@ Perl_getcwd_sv(pTHX_ register SV *sv)
     SvTAINTED_on(sv);
 #endif
 
+    PERL_ARGS_ASSERT_GETCWD_SV;
+
 #ifdef HAS_GETCWD
     {
 	char buf[MAXPATHLEN];
@@ -4173,6 +4255,9 @@ Perl_scan_version(pTHX_ const char *s, SV *rv, bool qv)
     bool vinf = FALSE;
     AV * const av = newAV();
     SV * const hv = newSVrv(rv, "version"); /* create an SV and upgrade the RV */
+
+    PERL_ARGS_ASSERT_SCAN_VERSION;
+
     (void)sv_upgrade(hv, SVt_PVHV); /* needs to be an HV type */
 
     while (isSPACE(*s)) /* leading whitespace is OK */
@@ -4373,6 +4458,7 @@ Perl_new_version(pTHX_ SV *ver)
 {
     dVAR;
     SV * const rv = newSV(0);
+    PERL_ARGS_ASSERT_NEW_VERSION;
     if ( sv_derived_from(ver,"version") ) /* can just copy directly */
     {
 	I32 key;
@@ -4458,6 +4544,8 @@ Perl_upg_version(pTHX_ SV *ver, bool qv)
     const MAGIC *mg;
 #endif
 
+    PERL_ARGS_ASSERT_UPG_VERSION;
+
     if ( SvNOK(ver) && !( SvPOK(ver) && sv_len(ver) == 3 ) )
     {
 	/* may get too much accuracy */ 
@@ -4550,6 +4638,9 @@ bool
 Perl_vverify(pTHX_ SV *vs)
 {
     SV *sv;
+
+    PERL_ARGS_ASSERT_VVERIFY;
+
     if ( SvROK(vs) )
 	vs = SvRV(vs);
 
@@ -4585,6 +4676,9 @@ Perl_vnumify(pTHX_ SV *vs)
     bool alpha = FALSE;
     SV * const sv = newSV(0);
     AV *av;
+
+    PERL_ARGS_ASSERT_VNUMIFY;
+
     if ( SvROK(vs) )
 	vs = SvRV(vs);
 
@@ -4663,6 +4757,9 @@ Perl_vnormal(pTHX_ SV *vs)
     bool alpha = FALSE;
     SV * const sv = newSV(0);
     AV *av;
+
+    PERL_ARGS_ASSERT_VNORMAL;
+
     if ( SvROK(vs) )
 	vs = SvRV(vs);
 
@@ -4718,6 +4815,9 @@ SV *
 Perl_vstringify(pTHX_ SV *vs)
 {
     SV *pv;
+
+    PERL_ARGS_ASSERT_VSTRINGIFY;
+
     if ( SvROK(vs) )
 	vs = SvRV(vs);
     
@@ -4749,6 +4849,9 @@ Perl_vcmp(pTHX_ SV *lhv, SV *rhv)
     I32 left = 0;
     I32 right = 0;
     AV *lav, *rav;
+
+    PERL_ARGS_ASSERT_VCMP;
+
     if ( SvROK(lhv) )
 	lhv = SvRV(lhv);
     if ( SvROK(rhv) )
@@ -5130,6 +5233,8 @@ Perl_parse_unicode_opts(pTHX_ const char **popt)
   const char *p = *popt;
   U32 opt = 0;
 
+  PERL_ARGS_ASSERT_PARSE_UNICODE_OPTS;
+
   if (*p) {
        if (isDIGIT(*p)) {
 	    opt = (U32) atoi(p);
@@ -5309,6 +5414,7 @@ Perl_stashpv_hvname_match(pTHX_ const COP *c, const HV *hv)
     const char * const stashpv = CopSTASHPV(c);
     const char * const name = HvNAME_get(hv);
     PERL_UNUSED_CONTEXT;
+    PERL_ARGS_ASSERT_STASHPV_HVNAME_MATCH;
 
     if (stashpv == name)
 	return TRUE;
@@ -5385,6 +5491,7 @@ Perl_init_global_struct(pTHX)
 void
 Perl_free_global_struct(pTHX_ struct perl_vars *plvarsp)
 {
+    PERL_ARGS_ASSERT_FREE_GLOBAL_STRUCT;
 # ifdef PERL_GLOBAL_STRUCT
 #  ifdef PERL_UNSET_VARS
     PERL_UNSET_VARS(plvarsp);
@@ -5583,6 +5690,7 @@ int
 Perl_my_sprintf(char *buffer, const char* pat, ...)
 {
     va_list args;
+    PERL_ARGS_ASSERT_MY_SPRINTF;
     va_start(args, pat);
     vsprintf(buffer, pat, args);
     va_end(args);
@@ -5608,6 +5716,7 @@ Perl_my_snprintf(char *buffer, const Size_t len, const char *format, ...)
     dTHX;
     int retval;
     va_list ap;
+    PERL_ARGS_ASSERT_MY_SNPRINTF;
     va_start(ap, format);
 #ifdef HAS_VSNPRINTF
     retval = vsnprintf(buffer, len, format, ap);
@@ -5639,6 +5748,9 @@ Perl_my_vsnprintf(char *buffer, const Size_t len, const char *format, va_list ap
     int retval;
 #ifdef NEED_VA_COPY
     va_list apc;
+
+    PERL_ARGS_ASSERT_MY_VSNPRINTF;
+
     Perl_va_copy(ap, apc);
 # ifdef HAS_VSNPRINTF
     retval = vsnprintf(buffer, len, format, apc);
@@ -5728,6 +5840,7 @@ Perl_my_cxt_init(pTHX_ int *index, size_t size)
 {
     dVAR;
     void *p;
+    PERL_ARGS_ASSERT_MY_CXT_INIT;
     if (*index == -1) {
 	/* this module hasn't been allocated an index yet */
 	MUTEX_LOCK(&PL_my_ctx_mutex);
@@ -5762,6 +5875,8 @@ Perl_my_cxt_index(pTHX_ const char *my_cxt_key)
     dVAR;
     int index;
 
+    PERL_ARGS_ASSERT_MY_CXT_INDEX;
+
     for (index = 0; index < PL_my_cxt_index; index++) {
 	const char *key = PL_my_cxt_keys[index];
 	/* try direct pointer compare first - there are chances to success,
@@ -5780,6 +5895,8 @@ Perl_my_cxt_init(pTHX_ const char *my_cxt_key, size_t size)
     void *p;
     int index;
 
+    PERL_ARGS_ASSERT_MY_CXT_INIT;
+
     index = Perl_my_cxt_index(aTHX_ my_cxt_key);
     if (index == -1) {
 	/* this module hasn't been allocated an index yet */
@@ -5866,6 +5983,8 @@ Perl_get_db_sub(pTHX_ SV **svp, CV *cv)
      * it's for informational purposes only.
      */
 
+    PERL_ARGS_ASSERT_GET_DB_SUB;
+
     save_item(dbsv);
     if (!PERLDB_SUB_NN) {
 	GV * const gv = CvGV(cv);