[Bug c++/107379] [13 regression] g++.dg/modules/adl-3_c.C and adl-4_b.C break as of r13-2887-gb04208895fed34
cvs-commit at gcc dot gnu.org
gcc-bugzilla@gcc.gnu.org
Thu Oct 27 18:11:04 GMT 2022
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107379
--- Comment #3 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jakub Jelinek <jakub@gcc.gnu.org>:
https://gcc.gnu.org/g:a33d623d2d3a78f5ef6f9e854946303e063eef63
commit r13-3528-ga33d623d2d3a78f5ef6f9e854946303e063eef63
Author: Jakub Jelinek <jakub@redhat.com>
Date: Thu Oct 27 20:10:18 2022 +0200
c++: Fix ICE on g++.dg/modules/adl-3_c.C [PR107379]
As mentioned in the PR, apparently my r13-2887 P1467R9 changes
regressed these tests on powerpc64le-linux with IEEE quad by default.
I believe my changes just uncovered a latent bug.
The problem is that push_namespace calls find_namespace_slot,
which does:
tree *slot = DECL_NAMESPACE_BINDINGS (ns)
->find_slot_with_hash (name, name ? IDENTIFIER_HASH_VALUE (name) : 0,
create_p ? INSERT : NO_INSERT);
In the <identifier_node 0x7fffe9f55ac0 details> ns case, slot is non-NULL
above with a binding_vector in it.
Then pushdecl is called and this does:
slot = find_namespace_slot (ns, name, ns ==
current_namespace);
where ns == current_namespace (ns is :: and name is details) is true.
So this again calls
tree *slot = DECL_NAMESPACE_BINDINGS (ns)
->find_slot_with_hash (name, name ? IDENTIFIER_HASH_VALUE
(name) : 0,
create_p ? INSERT : NO_INSERT);
but this time with create_p and so INSERT.
At this point we reach
if (insert == INSERT && m_size * 3 <= m_n_elements * 4)
expand ();
and when we are unlucky and the occupancy of the hash table just reached
3/4,
expand () is called and the hash table is reallocated. But when that
happens,
it means the slot pointer in the pushdecl caller (push_namespace) points to
freed memory and so any accesses to it in make_namespace_finish will be UB.
The following patch fixes it by calling find_namespace_slot again even if
it
was non-NULL, just doesn't assert it is *slot == ns in that case (because
it often is not).
2022-10-27 Jakub Jelinek <jakub@redhat.com>
PR c++/107379
* name-lookup.cc (push_namespace): Call find_namespace_slot again
after pushdecl as the hash table might be expanded during pushdecl.
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