mro.c 42.8 KB
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/*    mro.c
 *
 *    Copyright (c) 2007 Brandon L Black
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 *    Copyright (c) 2007, 2008, 2009, 2010, 2011 Larry Wall and others
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 *
 *    You may distribute under the terms of either the GNU General Public
 *    License or the Artistic License, as specified in the README file.
 *
 */

/*
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 * 'Which order shall we go in?' said Frodo.  'Eldest first, or quickest first?
 *  You'll be last either way, Master Peregrin.'
 *
 *     [p.101 of _The Lord of the Rings_, I/iii: "A Conspiracy Unmasked"]
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 */

/*
=head1 MRO Functions

These functions are related to the method resolution order of perl classes

=cut
*/

#include "EXTERN.h"
#define PERL_IN_MRO_C
#include "perl.h"

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static const struct mro_alg dfs_alg =
    {S_mro_get_linear_isa_dfs, "dfs", 3, 0, 0};

SV *
Perl_mro_get_private_data(pTHX_ struct mro_meta *const smeta,
			  const struct mro_alg *const which)
{
    SV **data;
    PERL_ARGS_ASSERT_MRO_GET_PRIVATE_DATA;

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    data = (SV **)Perl_hv_common(aTHX_ smeta->mro_linear_all, NULL,
				 which->name, which->length, which->kflags,
				 HV_FETCH_JUST_SV, NULL, which->hash);
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    if (!data)
	return NULL;

    /* If we've been asked to look up the private data for the current MRO, then
       cache it.  */
    if (smeta->mro_which == which)
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	smeta->mro_linear_current = *data;
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    return *data;
}

SV *
Perl_mro_set_private_data(pTHX_ struct mro_meta *const smeta,
			  const struct mro_alg *const which, SV *const data)
{
    PERL_ARGS_ASSERT_MRO_SET_PRIVATE_DATA;

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    if (!smeta->mro_linear_all) {
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	if (smeta->mro_which == which) {
	    /* If all we need to store is the current MRO's data, then don't use
	       memory on a hash with 1 element - store it direct, and signal
	       this by leaving the would-be-hash NULL.  */
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	    smeta->mro_linear_current = data;
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	    return data;
	} else {
	    HV *const hv = newHV();
	    /* Start with 2 buckets. It's unlikely we'll need more. */
	    HvMAX(hv) = 1;	
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	    smeta->mro_linear_all = hv;
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	    if (smeta->mro_linear_current) {
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		/* If we were storing something directly, put it in the hash
		   before we lose it. */
		Perl_mro_set_private_data(aTHX_ smeta, smeta->mro_which, 
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					  smeta->mro_linear_current);
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	    }
	}
    }

    /* We get here if we're storing more than one linearisation for this stash,
       or the linearisation we are storing is not that if its current MRO.  */

    if (smeta->mro_which == which) {
	/* If we've been asked to store the private data for the current MRO,
	   then cache it.  */
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	smeta->mro_linear_current = data;
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    }

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    if (!Perl_hv_common(aTHX_ smeta->mro_linear_all, NULL,
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			which->name, which->length, which->kflags,
			HV_FETCH_ISSTORE, data, which->hash)) {
	Perl_croak(aTHX_ "panic: hv_store() failed in set_mro_private_data() "
		   "for '%.*s' %d", (int) which->length, which->name,
		   which->kflags);
    }

    return data;
}

const struct mro_alg *
Perl_mro_get_from_name(pTHX_ SV *name) {
    SV **data;

    PERL_ARGS_ASSERT_MRO_GET_FROM_NAME;

    data = (SV **)Perl_hv_common(aTHX_ PL_registered_mros, name, NULL, 0, 0,
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				 HV_FETCH_JUST_SV, NULL, 0);
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    if (!data)
	return NULL;
    assert(SvTYPE(*data) == SVt_IV);
    assert(SvIOK(*data));
    return INT2PTR(const struct mro_alg *, SvUVX(*data));
}

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/*
=for apidoc mro_register
Registers a custom mro plugin.  See L<perlmroapi> for details.

=cut
*/

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void
Perl_mro_register(pTHX_ const struct mro_alg *mro) {
    SV *wrapper = newSVuv(PTR2UV(mro));

    PERL_ARGS_ASSERT_MRO_REGISTER;

    
    if (!Perl_hv_common(aTHX_ PL_registered_mros, NULL,
			mro->name, mro->length, mro->kflags,
			HV_FETCH_ISSTORE, wrapper, mro->hash)) {
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	SvREFCNT_dec_NN(wrapper);
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	Perl_croak(aTHX_ "panic: hv_store() failed in mro_register() "
		   "for '%.*s' %d", (int) mro->length, mro->name, mro->kflags);
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    }
}

struct mro_meta*
Perl_mro_meta_init(pTHX_ HV* stash)
{
    struct mro_meta* newmeta;

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    PERL_ARGS_ASSERT_MRO_META_INIT;
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    assert(HvAUX(stash));
    assert(!(HvAUX(stash)->xhv_mro_meta));
    Newxz(newmeta, 1, struct mro_meta);
    HvAUX(stash)->xhv_mro_meta = newmeta;
    newmeta->cache_gen = 1;
    newmeta->pkg_gen = 1;
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    newmeta->mro_which = &dfs_alg;
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    return newmeta;
}

#if defined(USE_ITHREADS)

/* for sv_dup on new threads */
struct mro_meta*
Perl_mro_meta_dup(pTHX_ struct mro_meta* smeta, CLONE_PARAMS* param)
{
    struct mro_meta* newmeta;

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    PERL_ARGS_ASSERT_MRO_META_DUP;
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    Newx(newmeta, 1, struct mro_meta);
    Copy(smeta, newmeta, 1, struct mro_meta);

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    if (newmeta->mro_linear_all) {
	newmeta->mro_linear_all
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	    = MUTABLE_HV(sv_dup_inc((const SV *)newmeta->mro_linear_all, param));
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	/* This is just acting as a shortcut pointer, and will be automatically
	   updated on the first get.  */
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	newmeta->mro_linear_current = NULL;
    } else if (newmeta->mro_linear_current) {
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	/* Only the current MRO is stored, so this owns the data.  */
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	newmeta->mro_linear_current
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	    = sv_dup_inc((const SV *)newmeta->mro_linear_current, param);
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    }

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    if (newmeta->mro_nextmethod)
	newmeta->mro_nextmethod
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	    = MUTABLE_HV(sv_dup_inc((const SV *)newmeta->mro_nextmethod, param));
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    if (newmeta->isa)
	newmeta->isa
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	    = MUTABLE_HV(sv_dup_inc((const SV *)newmeta->isa, param));
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    newmeta->super = NULL;

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    return newmeta;
}

#endif /* USE_ITHREADS */

/*
=for apidoc mro_get_linear_isa_dfs

Returns the Depth-First Search linearization of @ISA
the given stash.  The return value is a read-only AV*.
C<level> should be 0 (it is used internally in this
function's recursion).

You are responsible for C<SvREFCNT_inc()> on the
return value if you plan to store it anywhere
semi-permanently (otherwise it might be deleted
out from under you the next time the cache is
invalidated).

=cut
*/
static AV*
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S_mro_get_linear_isa_dfs(pTHX_ HV *stash, U32 level)
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{
    AV* retval;
    GV** gvp;
    GV* gv;
    AV* av;
    const HEK* stashhek;
    struct mro_meta* meta;
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    SV *our_name;
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    HV *stored = NULL;
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    PERL_ARGS_ASSERT_MRO_GET_LINEAR_ISA_DFS;
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    assert(HvAUX(stash));

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    stashhek
     = HvAUX(stash)->xhv_name_u.xhvnameu_name && HvENAME_HEK_NN(stash)
        ? HvENAME_HEK_NN(stash)
        : HvNAME_HEK(stash);

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    if (!stashhek)
      Perl_croak(aTHX_ "Can't linearize anonymous symbol table");

    if (level > 100)
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        Perl_croak(aTHX_
		  "Recursive inheritance detected in package '%"HEKf"'",
		   HEKfARG(stashhek));
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    meta = HvMROMETA(stash);

    /* return cache if valid */
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    if((retval = MUTABLE_AV(MRO_GET_PRIVATE_DATA(meta, &dfs_alg)))) {
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        return retval;
    }

    /* not in cache, make a new one */

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    retval = MUTABLE_AV(sv_2mortal(MUTABLE_SV(newAV())));
    /* We use this later in this function, but don't need a reference to it
       beyond the end of this function, so reference count is fine.  */
    our_name = newSVhek(stashhek);
    av_push(retval, our_name); /* add ourselves at the top */
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    /* fetch our @ISA */
    gvp = (GV**)hv_fetchs(stash, "ISA", FALSE);
    av = (gvp && (gv = *gvp) && isGV_with_GP(gv)) ? GvAV(gv) : NULL;

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    /* "stored" is used to keep track of all of the classnames we have added to
       the MRO so far, so we can do a quick exists check and avoid adding
       duplicate classnames to the MRO as we go.
       It's then retained to be re-used as a fast lookup for ->isa(), by adding
       our own name and "UNIVERSAL" to it.  */

    if(av && AvFILLp(av) >= 0) {
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        SV **svp = AvARRAY(av);
        I32 items = AvFILLp(av) + 1;

        /* foreach(@ISA) */
        while (items--) {
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            SV* const sv = *svp ? *svp : &PL_sv_undef;
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            HV* const basestash = gv_stashsv(sv, 0);
	    SV *const *subrv_p;
	    I32 subrv_items;
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	    svp++;
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            if (!basestash) {
                /* if no stash exists for this @ISA member,
                   simply add it to the MRO and move on */
		subrv_p = &sv;
		subrv_items = 1;
            }
            else {
                /* otherwise, recurse into ourselves for the MRO
                   of this @ISA member, and append their MRO to ours.
		   The recursive call could throw an exception, which
		   has memory management implications here, hence the use of
		   the mortal.  */
		const AV *const subrv
		    = mro_get_linear_isa_dfs(basestash, level + 1);

		subrv_p = AvARRAY(subrv);
		subrv_items = AvFILLp(subrv) + 1;
	    }
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	    if (stored) {
		while(subrv_items--) {
		    SV *const subsv = *subrv_p++;
		    /* LVALUE fetch will create a new undefined SV if necessary
		     */
		    HE *const he = hv_fetch_ent(stored, subsv, 1, 0);
		    assert(he);
		    if(HeVAL(he) != &PL_sv_undef) {
			/* It was newly created.  Steal it for our new SV, and
			   replace it in the hash with the "real" thing.  */
			SV *const val = HeVAL(he);
			HEK *const key = HeKEY_hek(he);

			HeVAL(he) = &PL_sv_undef;
			/* Save copying by making a shared hash key scalar. We
			   inline this here rather than calling
			   Perl_newSVpvn_share because we already have the
			   scalar, and we already have the hash key.  */
			assert(SvTYPE(val) == SVt_NULL);
			sv_upgrade(val, SVt_PV);
			SvPV_set(val, HEK_KEY(share_hek_hek(key)));
			SvCUR_set(val, HEK_LEN(key));
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			SvIsCOW_on(val);
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			SvPOK_on(val);
			if (HEK_UTF8(key))
			    SvUTF8_on(val);

			av_push(retval, val);
		    }
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		}
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            } else {
		/* We are the first (or only) parent. We can short cut the
		   complexity above, because our @ISA is simply us prepended
		   to our parent's @ISA, and our ->isa cache is simply our
		   parent's, with our name added.  */
		/* newSVsv() is slow. This code is only faster if we can avoid
		   it by ensuring that SVs in the arrays are shared hash key
		   scalar SVs, because we can "copy" them very efficiently.
		   Although to be fair, we can't *ensure* this, as a reference
		   to the internal array is returned by mro::get_linear_isa(),
		   so we'll have to be defensive just in case someone faffed
		   with it.  */
		if (basestash) {
		    SV **svp;
		    stored = MUTABLE_HV(sv_2mortal((SV*)newHVhv(HvMROMETA(basestash)->isa)));
		    av_extend(retval, subrv_items);
		    AvFILLp(retval) = subrv_items;
		    svp = AvARRAY(retval);
		    while(subrv_items--) {
			SV *const val = *subrv_p++;
			*++svp = SvIsCOW_shared_hash(val)
			    ? newSVhek(SvSHARED_HEK_FROM_PV(SvPVX(val)))
			    : newSVsv(val);
		    }
		} else {
		    /* They have no stash.  So create ourselves an ->isa cache
		       as if we'd copied it from what theirs should be.  */
		    stored = MUTABLE_HV(sv_2mortal(MUTABLE_SV(newHV())));
		    (void) hv_store(stored, "UNIVERSAL", 9, &PL_sv_undef, 0);
		    av_push(retval,
			    newSVhek(HeKEY_hek(hv_store_ent(stored, sv,
							    &PL_sv_undef, 0))));
		}
	    }
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        }
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    } else {
	/* We have no parents.  */
	stored = MUTABLE_HV(sv_2mortal(MUTABLE_SV(newHV())));
	(void) hv_store(stored, "UNIVERSAL", 9, &PL_sv_undef, 0);
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    }

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    (void) hv_store_ent(stored, our_name, &PL_sv_undef, 0);

    SvREFCNT_inc_simple_void_NN(stored);
    SvTEMP_off(stored);
    SvREADONLY_on(stored);

    meta->isa = stored;

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    /* now that we're past the exception dangers, grab our own reference to
       the AV we're about to use for the result. The reference owned by the
       mortals' stack will be released soon, so everything will balance.  */
    SvREFCNT_inc_simple_void_NN(retval);
    SvTEMP_off(retval);

    /* we don't want anyone modifying the cache entry but us,
       and we do so by replacing it completely */
    SvREADONLY_on(retval);

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    return MUTABLE_AV(Perl_mro_set_private_data(aTHX_ meta, &dfs_alg,
						MUTABLE_SV(retval)));
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}

/*
=for apidoc mro_get_linear_isa

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Returns the mro linearisation for the given stash.  By default, this
will be whatever C<mro_get_linear_isa_dfs> returns unless some
other MRO is in effect for the stash.  The return value is a
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read-only AV*.

You are responsible for C<SvREFCNT_inc()> on the
return value if you plan to store it anywhere
semi-permanently (otherwise it might be deleted
out from under you the next time the cache is
invalidated).

=cut
*/
AV*
Perl_mro_get_linear_isa(pTHX_ HV *stash)
{
    struct mro_meta* meta;
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    AV *isa;
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    PERL_ARGS_ASSERT_MRO_GET_LINEAR_ISA;
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    if(!SvOOK(stash))
        Perl_croak(aTHX_ "Can't linearize anonymous symbol table");

    meta = HvMROMETA(stash);
    if (!meta->mro_which)
        Perl_croak(aTHX_ "panic: invalid MRO!");
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    isa = meta->mro_which->resolve(aTHX_ stash, 0);

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    if (meta->mro_which != &dfs_alg) { /* skip for dfs, for speed */
	SV * const namesv =
	    (HvENAME(stash)||HvNAME(stash))
	      ? newSVhek(HvENAME_HEK(stash)
			  ? HvENAME_HEK(stash)
			  : HvNAME_HEK(stash))
	      : NULL;

	if(namesv && (AvFILLp(isa) == -1 || !sv_eq(*AvARRAY(isa), namesv)))
	{
	    AV * const old = isa;
	    SV **svp;
	    SV **ovp = AvARRAY(old);
	    SV * const * const oend = ovp + AvFILLp(old) + 1;
	    isa = (AV *)sv_2mortal((SV *)newAV());
	    av_extend(isa, AvFILLp(isa) = AvFILLp(old)+1);
	    *AvARRAY(isa) = namesv;
	    svp = AvARRAY(isa)+1;
	    while (ovp < oend) *svp++ = SvREFCNT_inc(*ovp++);
	}
	else SvREFCNT_dec(namesv);
    }

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    if (!meta->isa) {
	    HV *const isa_hash = newHV();
	    /* Linearisation didn't build it for us, so do it here.  */
	    SV *const *svp = AvARRAY(isa);
	    SV *const *const svp_end = svp + AvFILLp(isa) + 1;
	    const HEK *canon_name = HvENAME_HEK(stash);
	    if (!canon_name) canon_name = HvNAME_HEK(stash);

	    while (svp < svp_end) {
		(void) hv_store_ent(isa_hash, *svp++, &PL_sv_undef, 0);
	    }

	    (void) hv_common(isa_hash, NULL, HEK_KEY(canon_name),
			     HEK_LEN(canon_name), HEK_FLAGS(canon_name),
			     HV_FETCH_ISSTORE, &PL_sv_undef,
			     HEK_HASH(canon_name));
	    (void) hv_store(isa_hash, "UNIVERSAL", 9, &PL_sv_undef, 0);

	    SvREADONLY_on(isa_hash);

	    meta->isa = isa_hash;
    }

    return isa;
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}

/*
=for apidoc mro_isa_changed_in

Takes the necessary steps (cache invalidations, mostly)
when the @ISA of the given package has changed.  Invoked
by the C<setisa> magic, should not need to invoke directly.

=cut
*/
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/* Macro to avoid repeating the code five times. */
#define CLEAR_LINEAR(mEta)                                     \
    if (mEta->mro_linear_all) {                                 \
	SvREFCNT_dec(MUTABLE_SV(mEta->mro_linear_all));          \
	mEta->mro_linear_all = NULL;                              \
	/* This is just acting as a shortcut pointer.  */          \
	mEta->mro_linear_current = NULL;                            \
    } else if (mEta->mro_linear_current) {                           \
	/* Only the current MRO is stored, so this owns the data.  */ \
	SvREFCNT_dec(mEta->mro_linear_current);                        \
	mEta->mro_linear_current = NULL;                                \
    }

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void
Perl_mro_isa_changed_in(pTHX_ HV* stash)
{
    dVAR;
    HV* isarev;
    AV* linear_mro;
    HE* iter;
    SV** svp;
    I32 items;
    bool is_universal;
    struct mro_meta * meta;
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    HV *isa = NULL;
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    const HEK * const stashhek = HvENAME_HEK(stash);
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    const char * const stashname = HvENAME_get(stash);
    const STRLEN stashname_len = HvENAMELEN_get(stash);
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    PERL_ARGS_ASSERT_MRO_ISA_CHANGED_IN;

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    if(!stashname)
        Perl_croak(aTHX_ "Can't call mro_isa_changed_in() on anonymous symbol table");

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    /* wipe out the cached linearizations for this stash */
    meta = HvMROMETA(stash);
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    CLEAR_LINEAR(meta);
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    if (meta->isa) {
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	/* Steal it for our own purposes. */
	isa = (HV *)sv_2mortal((SV *)meta->isa);
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	meta->isa = NULL;
    }
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    /* Inc the package generation, since our @ISA changed */
    meta->pkg_gen++;

    /* Wipe the global method cache if this package
       is UNIVERSAL or one of its parents */

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    svp = hv_fetchhek(PL_isarev, stashhek, 0);
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    isarev = svp ? MUTABLE_HV(*svp) : NULL;
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    if((stashname_len == 9 && strEQ(stashname, "UNIVERSAL"))
        || (isarev && hv_exists(isarev, "UNIVERSAL", 9))) {
        PL_sub_generation++;
        is_universal = TRUE;
    }
    else { /* Wipe the local method cache otherwise */
        meta->cache_gen++;
	is_universal = FALSE;
    }

    /* wipe next::method cache too */
    if(meta->mro_nextmethod) hv_clear(meta->mro_nextmethod);

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    /* Changes to @ISA might turn overloading on */
    HvAMAGIC_on(stash);
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    /* pessimise derefs for now. Will get recalculated by Gv_AMupdate() */
    HvAUX(stash)->xhv_aux_flags &= ~HvAUXf_NO_DEREF;
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    /* DESTROY can be cached in SvSTASH. */
    if (!SvOBJECT(stash)) SvSTASH(stash) = NULL;

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    /* Iterate the isarev (classes that are our children),
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       wiping out their linearization, method and isa caches
       and upating PL_isarev. */
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    if(isarev) {
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        HV *isa_hashes = NULL;

       /* We have to iterate through isarev twice to avoid a chicken and
        * egg problem: if A inherits from B and both are in isarev, A might
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        * be processed before B and use B's previous linearisation.
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        */

       /* First iteration: Wipe everything, but stash away the isa hashes
        * since we still need them for updating PL_isarev.
        */

        if(hv_iterinit(isarev)) {
            /* Only create the hash if we need it; i.e., if isarev has
               any elements. */
            isa_hashes = (HV *)sv_2mortal((SV *)newHV());
        }
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        while((iter = hv_iternext(isarev))) {
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            HV* revstash = gv_stashsv(hv_iterkeysv(iter), 0);
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            struct mro_meta* revmeta;

            if(!revstash) continue;
            revmeta = HvMROMETA(revstash);
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	    CLEAR_LINEAR(revmeta);
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            if(!is_universal)
                revmeta->cache_gen++;
            if(revmeta->mro_nextmethod)
                hv_clear(revmeta->mro_nextmethod);
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	    if (!SvOBJECT(revstash)) SvSTASH(revstash) = NULL;
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	    (void)
	      hv_store(
	       isa_hashes, (const char*)&revstash, sizeof(HV *),
	       revmeta->isa ? (SV *)revmeta->isa : &PL_sv_undef, 0
	      );
	    revmeta->isa = NULL;
        }

       /* Second pass: Update PL_isarev. We can just use isa_hashes to
        * avoid another round of stash lookups. */

       /* isarev might be deleted from PL_isarev during this loop, so hang
        * on to it. */
        SvREFCNT_inc_simple_void_NN(sv_2mortal((SV *)isarev));

        if(isa_hashes) {
            hv_iterinit(isa_hashes);
            while((iter = hv_iternext(isa_hashes))) {
                HV* const revstash = *(HV **)HEK_KEY(HeKEY_hek(iter));
                HV * const isa = (HV *)HeVAL(iter);
                const HEK *namehek;

                /* We're starting at the 2nd element, skipping revstash */
                linear_mro = mro_get_linear_isa(revstash);
                svp = AvARRAY(linear_mro) + 1;
                items = AvFILLp(linear_mro);

                namehek = HvENAME_HEK(revstash);
                if (!namehek) namehek = HvNAME_HEK(revstash);

                while (items--) {
                    SV* const sv = *svp++;
                    HV* mroisarev;

                    HE *he = hv_fetch_ent(PL_isarev, sv, TRUE, 0);

                    /* That fetch should not fail.  But if it had to create
                       a new SV for us, then will need to upgrade it to an
                       HV (which sv_upgrade() can now do for us). */

                    mroisarev = MUTABLE_HV(HeVAL(he));

                    SvUPGRADE(MUTABLE_SV(mroisarev), SVt_PVHV);

                    /* This hash only ever contains PL_sv_yes. Storing it
                       over itself is almost as cheap as calling hv_exists,
                       so on aggregate we expect to save time by not making
                       two calls to the common HV code for the case where
                       it doesn't exist.  */
	   
                    (void)
638
                      hv_storehek(mroisarev, namehek, &PL_sv_yes);
639 640 641 642 643
                }

                if((SV *)isa != &PL_sv_undef)
                    mro_clean_isarev(
                     isa, HEK_KEY(namehek), HEK_LEN(namehek),
644 645
                     HvMROMETA(revstash)->isa, HEK_HASH(namehek),
                     HEK_UTF8(namehek)
646 647
                    );
            }
648 649 650
        }
    }

651 652
    /* Now iterate our MRO (parents), adding ourselves and everything from
       our isarev to their isarev.
653 654 655 656 657 658 659 660 661 662 663 664 665 666
    */

    /* We're starting at the 2nd element, skipping ourselves here */
    linear_mro = mro_get_linear_isa(stash);
    svp = AvARRAY(linear_mro) + 1;
    items = AvFILLp(linear_mro);

    while (items--) {
        SV* const sv = *svp++;
        HV* mroisarev;

        HE *he = hv_fetch_ent(PL_isarev, sv, TRUE, 0);

	/* That fetch should not fail.  But if it had to create a new SV for
667 668
	   us, then will need to upgrade it to an HV (which sv_upgrade() can
	   now do for us. */
669

670
        mroisarev = MUTABLE_HV(HeVAL(he));
671

672
	SvUPGRADE(MUTABLE_SV(mroisarev), SVt_PVHV);
673 674 675 676 677 678

	/* This hash only ever contains PL_sv_yes. Storing it over itself is
	   almost as cheap as calling hv_exists, so on aggregate we expect to
	   save time by not making two calls to the common HV code for the
	   case where it doesn't exist.  */
	   
679
	(void)hv_storehek(mroisarev, stashhek, &PL_sv_yes);
680
    }
681

682
    /* Delete our name from our former parents' isarevs. */
683
    if(isa && HvARRAY(isa))
684
        mro_clean_isarev(isa, stashname, stashname_len, meta->isa,
685
                         HEK_HASH(stashhek), HEK_UTF8(stashhek));
686 687 688 689 690
}

/* Deletes name from all the isarev entries listed in isa */
STATIC void
S_mro_clean_isarev(pTHX_ HV * const isa, const char * const name,
691 692
                         const STRLEN len, HV * const exceptions, U32 hash,
                         U32 flags)
693 694 695 696 697
{
    HE* iter;

    PERL_ARGS_ASSERT_MRO_CLEAN_ISAREV;

698
    /* Delete our name from our former parents' isarevs. */
699 700 701 702 703
    if(isa && HvARRAY(isa) && hv_iterinit(isa)) {
        SV **svp;
        while((iter = hv_iternext(isa))) {
            I32 klen;
            const char * const key = hv_iterkey(iter, &klen);
704 705 706
            if(exceptions && hv_exists(exceptions, key, HeKUTF8(iter) ? -klen : klen))
                continue;
            svp = hv_fetch(PL_isarev, key, HeKUTF8(iter) ? -klen : klen, 0);
707 708
            if(svp) {
                HV * const isarev = (HV *)*svp;
709 710
                (void)hv_common(isarev, NULL, name, len, flags,
                                G_DISCARD|HV_DELETE, NULL, hash);
711 712 713
                if(!HvARRAY(isarev) || !HvUSEDKEYS(isarev))
                    (void)hv_delete(PL_isarev, key,
                                        HeKUTF8(iter) ? -klen : klen, G_DISCARD);
714 715 716 717 718
            }
        }
    }
}

719 720 721 722
/*
=for apidoc mro_package_moved

Call this function to signal to a stash that it has been assigned to
723
another spot in the stash hierarchy.  C<stash> is the stash that has been
724
assigned.  C<oldstash> is the stash it replaces, if any.  C<gv> is the glob
725 726 727 728 729 730 731 732 733 734 735 736 737
that is actually being assigned to.

This can also be called with a null first argument to
indicate that C<oldstash> has been deleted.

This function invalidates isa caches on the old stash, on all subpackages
nested inside it, and on the subclasses of all those, including
non-existent packages that have corresponding entries in C<stash>.

It also sets the effective names (C<HvENAME>) on all the stashes as
appropriate.

If the C<gv> is present and is not in the symbol table, then this function
738
simply returns.  This checked will be skipped if C<flags & 1>.
739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778

=cut
*/
void
Perl_mro_package_moved(pTHX_ HV * const stash, HV * const oldstash,
                       const GV * const gv, U32 flags)
{
    SV *namesv;
    HEK **namep;
    I32 name_count;
    HV *stashes;
    HE* iter;

    PERL_ARGS_ASSERT_MRO_PACKAGE_MOVED;
    assert(stash || oldstash);

    /* Determine the name(s) of the location that stash was assigned to
     * or from which oldstash was removed.
     *
     * We cannot reliably use the name in oldstash, because it may have
     * been deleted from the location in the symbol table that its name
     * suggests, as in this case:
     *
     *   $globref = \*foo::bar::;
     *   Symbol::delete_package("foo");
     *   *$globref = \%baz::;
     *   *$globref = *frelp::;
     *      # calls mro_package_moved(%frelp::, %baz::, *$globref, NULL, 0)
     *
     * So we get it from the gv. But, since the gv may no longer be in the
     * symbol table, we check that first. The only reliable way to tell is
     * to see whether its stash has an effective name and whether the gv
     * resides in that stash under its name. That effective name may be
     * different from what gv_fullname4 would use.
     * If flags & 1, the caller has asked us to skip the check.
     */
    if(!(flags & 1)) {
	SV **svp;
	if(
	 !GvSTASH(gv) || !HvENAME(GvSTASH(gv)) ||
779
	 !(svp = hv_fetchhek(GvSTASH(gv), GvNAME_HEK(gv), 0)) ||
780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806
	 *svp != (SV *)gv
	) return;
    }
    assert(SvOOK(GvSTASH(gv)));
    assert(GvNAMELEN(gv));
    assert(GvNAME(gv)[GvNAMELEN(gv) - 1] == ':');
    assert(GvNAMELEN(gv) == 1 || GvNAME(gv)[GvNAMELEN(gv) - 2] == ':');
    name_count = HvAUX(GvSTASH(gv))->xhv_name_count;
    if (!name_count) {
	name_count = 1;
	namep = &HvAUX(GvSTASH(gv))->xhv_name_u.xhvnameu_name;
    }
    else {
	namep = HvAUX(GvSTASH(gv))->xhv_name_u.xhvnameu_names;
	if (name_count < 0) ++namep, name_count = -name_count - 1;
    }
    if (name_count == 1) {
	if (HEK_LEN(*namep) == 4 && strnEQ(HEK_KEY(*namep), "main", 4)) {
	    namesv = GvNAMELEN(gv) == 1
		? newSVpvs_flags(":", SVs_TEMP)
		: newSVpvs_flags("",  SVs_TEMP);
	}
	else {
	    namesv = sv_2mortal(newSVhek(*namep));
	    if (GvNAMELEN(gv) == 1) sv_catpvs(namesv, ":");
	    else                    sv_catpvs(namesv, "::");
	}
807 808 809
	if (GvNAMELEN(gv) != 1) {
	    sv_catpvn_flags(
		namesv, GvNAME(gv), GvNAMELEN(gv) - 2,
810
	                                  /* skip trailing :: */
811 812 813
		GvNAMEUTF8(gv) ? SV_CATUTF8 : SV_CATBYTES
	    );
        }
814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829
    }
    else {
	SV *aname;
	namesv = sv_2mortal((SV *)newAV());
	while (name_count--) {
	    if(HEK_LEN(*namep) == 4 && strnEQ(HEK_KEY(*namep), "main", 4)){
		aname = GvNAMELEN(gv) == 1
		         ? newSVpvs(":")
		         : newSVpvs("");
		namep++;
	    }
	    else {
		aname = newSVhek(*namep++);
		if (GvNAMELEN(gv) == 1) sv_catpvs(aname, ":");
		else                    sv_catpvs(aname, "::");
	    }
830 831 832
	    if (GvNAMELEN(gv) != 1) {
		sv_catpvn_flags(
		    aname, GvNAME(gv), GvNAMELEN(gv) - 2,
833
	                                  /* skip trailing :: */
834 835 836
		    GvNAMEUTF8(gv) ? SV_CATUTF8 : SV_CATBYTES
		);
            }
837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885
	    av_push((AV *)namesv, aname);
	}
    }

    /* Get a list of all the affected classes. */
    /* We cannot simply pass them all to mro_isa_changed_in to avoid
       the list, as that function assumes that only one package has
       changed. It does not work with:

          @foo::ISA = qw( B B::B );
          *B:: = delete $::{"A::"};

       as neither B nor B::B can be updated before the other, since they
       will reset caches on foo, which will see either B or B::B with the
       wrong name. The names must be set on *all* affected stashes before
       we do anything else. (And linearisations must be cleared, too.)
     */
    stashes = (HV *) sv_2mortal((SV *)newHV());
    mro_gather_and_rename(
     stashes, (HV *) sv_2mortal((SV *)newHV()),
     stash, oldstash, namesv
    );

    /* Once the caches have been wiped on all the classes, call
       mro_isa_changed_in on each. */
    hv_iterinit(stashes);
    while((iter = hv_iternext(stashes))) {
	HV * const stash = *(HV **)HEK_KEY(HeKEY_hek(iter));
	if(HvENAME(stash)) {
	    /* We have to restore the original meta->isa (that
	       mro_gather_and_rename set aside for us) this way, in case
	       one class in this list is a superclass of a another class
	       that we have already encountered. In such a case, meta->isa
	       will have been overwritten without old entries being deleted 
	       from PL_isarev. */
	    struct mro_meta * const meta = HvMROMETA(stash);
	    if(meta->isa != (HV *)HeVAL(iter)){
		SvREFCNT_dec(meta->isa);
		meta->isa
		 = HeVAL(iter) == &PL_sv_yes
		    ? NULL
		    : (HV *)HeVAL(iter);
		HeVAL(iter) = NULL; /* We donated our reference count. */
	    }
	    mro_isa_changed_in(stash);
	}
    }
}

886
STATIC void
887 888 889
S_mro_gather_and_rename(pTHX_ HV * const stashes, HV * const seen_stashes,
                              HV *stash, HV *oldstash, SV *namesv)
{
890 891
    XPVHV* xhv;
    HE *entry;
892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956
    I32 riter = -1;
    I32 items = 0;
    const bool stash_had_name = stash && HvENAME(stash);
    bool fetched_isarev = FALSE;
    HV *seen = NULL;
    HV *isarev = NULL;
    SV **svp = NULL;

    PERL_ARGS_ASSERT_MRO_GATHER_AND_RENAME;

    /* We use the seen_stashes hash to keep track of which packages have
       been encountered so far. This must be separate from the main list of
       stashes, as we need to distinguish between stashes being assigned
       and stashes being replaced/deleted. (A nested stash can be on both
       sides of an assignment. We cannot simply skip iterating through a
       stash on the right if we have seen it on the left, as it will not
       get its ename assigned to it.)

       To avoid allocating extra SVs, instead of a bitfield we can make
       bizarre use of immortals:

        &PL_sv_undef:  seen on the left  (oldstash)
        &PL_sv_no   :  seen on the right (stash)
        &PL_sv_yes  :  seen on both sides

     */

    if(oldstash) {
	/* Add to the big list. */
	struct mro_meta * meta;
	HE * const entry
	 = (HE *)
	     hv_common(
	      seen_stashes, NULL, (const char *)&oldstash, sizeof(HV *), 0,
	      HV_FETCH_LVALUE|HV_FETCH_EMPTY_HE, NULL, 0
	     );
	if(HeVAL(entry) == &PL_sv_undef || HeVAL(entry) == &PL_sv_yes) {
	    oldstash = NULL;
	    goto check_stash;
	}
	HeVAL(entry)
	 = HeVAL(entry) == &PL_sv_no ? &PL_sv_yes : &PL_sv_undef;
	meta = HvMROMETA(oldstash);
	(void)
	  hv_store(
	   stashes, (const char *)&oldstash, sizeof(HV *),
	   meta->isa
	    ? SvREFCNT_inc_simple_NN((SV *)meta->isa)
	    : &PL_sv_yes,
	   0
	  );
	CLEAR_LINEAR(meta);

	/* Update the effective name. */
	if(HvENAME_get(oldstash)) {
	    const HEK * const enamehek = HvENAME_HEK(oldstash);
	    if(SvTYPE(namesv) == SVt_PVAV) {
		items = AvFILLp((AV *)namesv) + 1;
		svp = AvARRAY((AV *)namesv);
	    }
	    else {
		items = 1;
		svp = &namesv;
	    }
	    while (items--) {
957
                const U32 name_utf8 = SvUTF8(*svp);
958
		STRLEN len;
959 960 961 962
		const char *name = SvPVx_const(*svp, len);
		if(PL_stashcache) {
                    DEBUG_o(Perl_deb(aTHX_ "mro_gather_and_rename clearing PL_stashcache for '%"SVf"'\n",
                                     *svp));
963
		   (void)hv_delete(PL_stashcache, name, name_utf8 ? -(I32)len : (I32)len, G_DISCARD);
964 965
                }
                ++svp;
966
	        hv_ename_delete(oldstash, name, len, name_utf8);
967 968 969 970 971 972

		if (!fetched_isarev) {
		    /* If the name deletion caused a name change, then we
		     * are not going to call mro_isa_changed_in with this
		     * name (and not at all if it has become anonymous) so
		     * we need to delete old isarev entries here, both
973
		     * those in the superclasses and this class's own list
974 975 976 977 978
		     * of subclasses. We simply delete the latter from
		     * PL_isarev, since we still need it. hv_delete morti-
		     * fies it for us, so sv_2mortal is not necessary. */
		    if(HvENAME_HEK(oldstash) != enamehek) {
			if(meta->isa && HvARRAY(meta->isa))
979 980
			    mro_clean_isarev(meta->isa, name, len, 0, 0,
					     name_utf8 ? HVhek_UTF8 : 0);
981 982
			isarev = (HV *)hv_delete(PL_isarev, name,
                                                    name_utf8 ? -(I32)len : (I32)len, 0);
983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999
			fetched_isarev=TRUE;
		    }
		}
	    }
	}
    }
   check_stash:
    if(stash) {
	if(SvTYPE(namesv) == SVt_PVAV) {
	    items = AvFILLp((AV *)namesv) + 1;
	    svp = AvARRAY((AV *)namesv);
	}
	else {
	    items = 1;
	    svp = &namesv;
	}
	while (items--) {
1000
            const U32 name_utf8 = SvUTF8(*svp);
1001 1002
	    STRLEN len;
	    const char *name = SvPVx_const(*svp++, len);
1003
	    hv_ename_add(stash, name, len, name_utf8);
1004 1005 1006 1007 1008
	}

       /* Add it to the big list if it needs
	* mro_isa_changed_in called on it. That happens if it was
	* detached from the symbol table (so it had no HvENAME) before
1009
	* being assigned to the spot named by the 'name' variable, because
1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065
	* its cached isa linearisation is now stale (the effective name
	* having changed), and subclasses will then use that cache when
	* mro_package_moved calls mro_isa_changed_in. (See
	* [perl #77358].)
	*
	* If it did have a name, then its previous name is still
	* used in isa caches, and there is no need for
	* mro_package_moved to call mro_isa_changed_in.
	*/

	entry
	 = (HE *)
	     hv_common(
	      seen_stashes, NULL, (const char *)&stash, sizeof(HV *), 0,
	      HV_FETCH_LVALUE|HV_FETCH_EMPTY_HE, NULL, 0
	     );
	if(HeVAL(entry) == &PL_sv_yes || HeVAL(entry) == &PL_sv_no)
	    stash = NULL;
	else {
	    HeVAL(entry)
	     = HeVAL(entry) == &PL_sv_undef ? &PL_sv_yes : &PL_sv_no;
	    if(!stash_had_name)
	    {
		struct mro_meta * const meta = HvMROMETA(stash);
		(void)
		  hv_store(
		   stashes, (const char *)&stash, sizeof(HV *),
		   meta->isa
		    ? SvREFCNT_inc_simple_NN((SV *)meta->isa)
		    : &PL_sv_yes,
		   0
		  );
		CLEAR_LINEAR(meta);
	    }
	}
    }

    if(!stash && !oldstash)
	/* Both stashes have been encountered already. */
	return;

    /* Add all the subclasses to the big list. */
    if(!fetched_isarev) {
	/* If oldstash is not null, then we can use its HvENAME to look up
	   the isarev hash, since all its subclasses will be listed there.
	   It will always have an HvENAME. It the HvENAME was removed
	   above, then fetch_isarev will be true, and this code will not be
	   reached.

	   If oldstash is null, then this is an empty spot with no stash in
	   it, so subclasses could be listed in isarev hashes belonging to
	   any of the names, so we have to check all of them.
	 */
	assert(!oldstash || HvENAME(oldstash));
	if (oldstash) {
	    /* Extra variable to avoid a compiler warning */
1066
	    const HEK * const hvename = HvENAME_HEK(oldstash);
1067
	    fetched_isarev = TRUE;
1068
	    svp = hv_fetchhek(PL_isarev, hvename, 0);
1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092
	    if (svp) isarev = MUTABLE_HV(*svp);
	}
	else if(SvTYPE(namesv) == SVt_PVAV) {
	    items = AvFILLp((AV *)namesv) + 1;
	    svp = AvARRAY((AV *)namesv);
	}
	else {
	    items = 1;
	    svp = &namesv;
	}
    }
    if(
        isarev || !fetched_isarev
    ) {
      while (fetched_isarev || items--) {
	HE *iter;

	if (!fetched_isarev) {
	    HE * const he = hv_fetch_ent(PL_isarev, *svp++, 0, 0);
	    if (!he || !(isarev = MUTABLE_HV(HeVAL(he)))) continue;
	}

	hv_iterinit(isarev);
	while((iter = hv_iternext(isarev))) {
1093
	    HV* revstash = gv_stashsv(hv_iterkeysv(iter), 0);
1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141
	    struct mro_meta * meta;

	    if(!revstash) continue;
	    meta = HvMROMETA(revstash);
	    (void)
	      hv_store(
	       stashes, (const char *)&revstash, sizeof(HV *),
	       meta->isa
	        ? SvREFCNT_inc_simple_NN((SV *)meta->isa)
	        : &PL_sv_yes,
	       0
	      );
	    CLEAR_LINEAR(meta);
        }

	if (fetched_isarev) break;
      }
    }

    /* This is partly based on code in hv_iternext_flags. We are not call-
       ing that here, as we want to avoid resetting the hash iterator. */

    /* Skip the entire loop if the hash is empty.   */
    if(oldstash && HvUSEDKEYS(oldstash)) { 
	xhv = (XPVHV*)SvANY(oldstash);
	seen = (HV *) sv_2mortal((SV *)newHV());

	/* Iterate through entries in the oldstash, adding them to the
	   list, meanwhile doing the equivalent of $seen{$key} = 1.
	 */

	while (++riter <= (I32)xhv->xhv_max) {
	    entry = (HvARRAY(oldstash))[riter];

	    /* Iterate through the entries in this list */
	    for(; entry; entry = HeNEXT(entry)) {
		const char* key;
		I32 len;

		/* If this entry is not a glob, ignore it.
		   Try the next.  */
		if (!isGV(HeVAL(entry))) continue;

		key = hv_iterkey(entry, &len);
		if ((len > 1 && key[len-2] == ':' && key[len-1] == ':')
		 || (len == 1 && key[0] == ':')) {
		    HV * const oldsubstash = GvHV(HeVAL(entry));
		    SV ** const stashentry
1142
		     = stash ? hv_fetch(stash, key, HeUTF8(entry) ? -(I32)len : (I32)len, 0) : NULL;
1143 1144 1145 1146 1147 1148 1149
		    HV *substash = NULL;

		    /* Avoid main::main::main::... */
		    if(oldsubstash == oldstash) continue;

		    if(
		        (
1150
		            stashentry && *stashentry && isGV(*stashentry)
1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169
		         && (substash = GvHV(*stashentry))
		        )
		     || (oldsubstash && HvENAME_get(oldsubstash))
		    )
		    {
			/* Add :: and the key (minus the trailing ::)
			   to each name. */
			SV *subname;
			if(SvTYPE(namesv) == SVt_PVAV) {
			    SV *aname;
			    items = AvFILLp((AV *)namesv) + 1;
			    svp = AvARRAY((AV *)namesv);
			    subname = sv_2mortal((SV *)newAV());
			    while (items--) {
				aname = newSVsv(*svp++);
				if (len == 1)
				    sv_catpvs(aname, ":");
				else {
				    sv_catpvs(aname, "::");
1170 1171 1172 1173 1174
				    sv_catpvn_flags(
					aname, key, len-2,
					HeUTF8(entry)
					   ? SV_CATUTF8 : SV_CATBYTES
				    );
1175 1176 1177 1178 1179 1180 1181 1182 1183
				}
				av_push((AV *)subname, aname);
			    }
			}
			else {
			    subname = sv_2mortal(newSVsv(namesv));
			    if (len == 1) sv_catpvs(subname, ":");
			    else {
				sv_catpvs(subname, "::");
1184 1185 1186 1187
				sv_catpvn_flags(
				   subname, key, len-2,
				   HeUTF8(entry) ? SV_CATUTF8 : SV_CATBYTES
				);
1188 1189 1190 1191 1192 1193 1194 1195
			    }
			}
			mro_gather_and_rename(
			     stashes, seen_stashes,
			     substash, oldsubstash, subname
			);
		    }

1196
		    (void)hv_store(seen, key, HeUTF8(entry) ? -(I32)len : (I32)len, &PL_sv_yes, 0);
1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227
		}
	    }
	}
    }

    /* Skip the entire loop if the hash is empty.   */
    if (stash && HvUSEDKEYS(stash)) {
	xhv = (XPVHV*)SvANY(stash);
	riter = -1;

	/* Iterate through the new stash, skipping $seen{$key} items,
	   calling mro_gather_and_rename(stashes,seen,entry,NULL, ...). */
	while (++riter <= (I32)xhv->xhv_max) {
	    entry = (HvARRAY(stash))[riter];

	    /* Iterate through the entries in this list */
	    for(; entry; entry = HeNEXT(entry)) {
		const char* key;
		I32 len;

		/* If this entry is not a glob, ignore it.
		   Try the next.  */
		if (!isGV(HeVAL(entry))) continue;

		key = hv_iterkey(entry, &len);
		if ((len > 1 && key[len-2] == ':' && key[len-1] == ':')
		 || (len == 1 && key[0] == ':')) {
		    HV *substash;

		    /* If this entry was seen when we iterated through the
		       oldstash, skip it. */
1228
		    if(seen && hv_exists(seen, key, HeUTF8(entry) ? -(I32)len : (I32)len)) continue;
1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252

		    /* We get here only if this stash has no corresponding
		       entry in the stash being replaced. */

		    substash = GvHV(HeVAL(entry));
		    if(substash) {
			SV *subname;

			/* Avoid checking main::main::main::... */
			if(substash == stash) continue;

			/* Add :: and the key (minus the trailing ::)
			   to each name. */
			if(SvTYPE(namesv) == SVt_PVAV) {
			    SV *aname;
			    items = AvFILLp((AV *)namesv) + 1;
			    svp = AvARRAY((AV *)namesv);
			    subname = sv_2mortal((SV *)newAV());
			    while (items--) {
				aname = newSVsv(*svp++);
				if (len == 1)
				    sv_catpvs(aname, ":");
				else {
				    sv_catpvs(aname, "::");
1253 1254 1255 1256 1257
				    sv_catpvn_flags(
					aname, key, len-2,
					HeUTF8(entry)
					   ? SV_CATUTF8 : SV_CATBYTES
				    );
1258 1259 1260 1261 1262 1263 1264 1265 1266
				}
				av_push((AV *)subname, aname);
			    }
			}
			else {
			    subname = sv_2mortal(newSVsv(namesv));
			    if (len == 1) sv_catpvs(subname, ":");
			    else {
				sv_catpvs(subname, "::");
1267 1268 1269 1270
				sv_catpvn_flags(
				   subname, key, len-2,
				   HeUTF8(entry) ? SV_CATUTF8 : SV_CATBYTES
				);
1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283
			    }
			}
			mro_gather_and_rename(
			  stashes, seen_stashes,
			  substash, NULL, subname
			);
		    }
		}
	    }
	}
    }
}

1284 1285 1286 1287 1288 1289 1290 1291
/*
=for apidoc mro_method_changed_in

Invalidates method caching on any child classes
of the given stash, so that they might notice
the changes in this one.

Ideally, all instances of C<PL_sub_generation++> in
1292
perl source outside of F<mro.c> should be
1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316
replaced by calls to this.

Perl automatically handles most of the common
ways a method might be redefined.  However, there
are a few ways you could change a method in a stash
without the cache code noticing, in which case you
need to call this method afterwards:

1) Directly manipulating the stash HV entries from
XS code.

2) Assigning a reference to a readonly scalar
constant into a stash entry in order to create
a constant subroutine (like constant.pm
does).

This same method is available from pure perl
via, C<mro::method_changed_in(classname)>.

=cut
*/
void
Perl_mro_method_changed_in(pTHX_ HV *stash)
{
1317 1318
    const char * const stashname = HvENAME_get(stash);
    const STRLEN stashname_len = HvENAMELEN_get(stash);
1319

1320
    SV ** const svp = hv_fetchhek(PL_isarev, HvENAME_HEK(stash), 0);
1321 1322 1323
    HV * const isarev = svp ? MUTABLE_HV(*svp) : NULL;

    PERL_ARGS_ASSERT_MRO_METHOD_CHANGED_IN;
1324 1325 1326 1327 1328 1329 1330

    if(!stashname)
        Perl_croak(aTHX_ "Can't call mro_method_changed_in() on anonymous symbol table");

    /* Inc the package generation, since a local method changed */
    HvMROMETA(stash)->pkg_gen++;

1331 1332 1333
    /* DESTROY can be cached in SvSTASH. */
    if (!SvOBJECT(stash)) SvSTASH(stash) = NULL;

1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348
    /* If stash is UNIVERSAL, or one of UNIVERSAL's parents,
       invalidate all method caches globally */
    if((stashname_len == 9 && strEQ(stashname, "UNIVERSAL"))
        || (isarev && hv_exists(isarev, "UNIVERSAL", 9))) {
        PL_sub_generation++;
        return;
    }

    /* else, invalidate the method caches of all child classes,
       but not itself */
    if(isarev) {
	HE* iter;

        hv_iterinit(isarev);
        while((iter = hv_iternext(isarev))) {
1349
            HV* const revstash = gv_stashsv(hv_iterkeysv(iter), 0);
1350 1351 1352 1353 1354 1355 1356
            struct mro_meta* mrometa;

            if(!revstash) continue;
            mrometa = HvMROMETA(revstash);
            mrometa->cache_gen++;
            if(mrometa->mro_nextmethod)
                hv_clear(mrometa->mro_nextmethod);
1357
            if (!SvOBJECT(revstash)) SvSTASH(revstash) = NULL;
1358 1359
        }
    }
1360 1361 1362 1363

    /* The method change may be due to *{$package . "::()"} = \&nil; in
       overload.pm. */
    HvAMAGIC_on(stash);
1364 1365
    /* pessimise derefs for now. Will get recalculated by Gv_AMupdate() */
    HvAUX(stash)->xhv_aux_flags &= ~HvAUXf_NO_DEREF;
1366 1367
}

1368 1369 1370 1371 1372 1373
void
Perl_mro_set_mro(pTHX_ struct mro_meta *const meta, SV *const name)
{
    const struct mro_alg *const which = Perl_mro_get_from_name(aTHX_ name);
 
    PERL_ARGS_ASSERT_MRO_SET_MRO;
1374

1375 1376 1377 1378
    if (!which)
        Perl_croak(aTHX_ "Invalid mro name: '%"SVf"'", name);

    if(meta->mro_which != which) {
1379
	if (meta->mro_linear_current && !meta->mro_linear_all) {
1380 1381 1382
	    /* If we were storing something directly, put it in the hash before
	       we lose it. */
	    Perl_mro_set_private_data(aTHX_ meta, meta->mro_which, 
1383
				      MUTABLE_SV(meta->mro_linear_current));
1384 1385 1386
	}
	meta->mro_which = which;
	/* Scrub our cached pointer to the private data.  */
1387
	meta->mro_linear_current = NULL;
1388 1389 1390 1391 1392
        /* Only affects local method cache, not
           even child classes */
        meta->cache_gen++;
        if(meta->mro_nextmethod)
            hv_clear(meta->mro_nextmethod);
1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405
    }
}

#include "XSUB.h"

XS(XS_mro_method_changed_in);

void
Perl_boot_core_mro(pTHX)
{
    dVAR;
    static const char file[] = __FILE__;

1406 1407
    Perl_mro_register(aTHX_ &dfs_alg);

1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418
    newXSproto("mro::method_changed_in", XS_mro_method_changed_in, file, "$");
}

XS(XS_mro_method_changed_in)
{
    dVAR;
    dXSARGS;
    SV* classname;
    HV* class_stash;

    if(items != 1)
1419
	croak_xs_usage(cv, "classname");
1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434
    
    classname = ST(0);

    class_stash = gv_stashsv(classname, 0);
    if(!class_stash) Perl_croak(aTHX_ "No such class: '%"SVf"'!", SVfARG(classname));

    mro_method_changed_in(class_stash);

    XSRETURN_EMPTY;
}

/*
 * Local variables:
 * c-indentation-style: bsd
 * c-basic-offset: 4
1435
 * indent-tabs-mode: nil
1436 1437
 * End:
 *
1438
 * ex: set ts=8 sts=4 sw=4 et:
1439
 */