[Bug c++/94219] ICE in cxx_eval_bare_aggregate, at cp/constexpr.c:3790
cvs-commit at gcc dot gnu.org
gcc-bugzilla@gcc.gnu.org
Sat Apr 4 16:18:02 GMT 2020
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94219
--- Comment #2 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Patrick Palka <ppalka@gcc.gnu.org>:
https://gcc.gnu.org/g:37244b217a7329792f4ec48027f63cf5010b0ea8
commit r10-7556-g37244b217a7329792f4ec48027f63cf5010b0ea8
Author: Patrick Palka <ppalka@redhat.com>
Date: Thu Apr 2 12:59:34 2020 -0400
c++: Fix constexpr evaluation of self-modifying CONSTRUCTORs [PR94219]
This PR reveals that cxx_eval_bare_aggregate and cxx_eval_store_expression
do
not anticipate that a constructor element's initializer could mutate the
underlying CONSTRUCTOR. Evaluation of the initializer could add new
elements to
the underlying CONSTRUCTOR, thereby potentially invalidating any pointers
to
or assumptions about the CONSTRUCTOR's elements, and so these routines
should be
prepared for that.
To fix this problem, this patch makes cxx_eval_bare_aggregate and
cxx_eval_store_expression recompute the constructor_elt pointers through
which
we're assigning, after it evaluates the initializer. Care is taken to to
not
slow down the common case where the initializer does not modify the
underlying
CONSTRUCTOR.
gcc/cp/ChangeLog:
PR c++/94219
PR c++/94205
* constexpr.c (get_or_insert_ctor_field): Split out (while adding
support for VECTOR_TYPEs, and optimizations for the common case)
from ...
(cxx_eval_store_expression): ... here. Rename local variable
'changed_active_union_member_p' to 'activated_union_member_p'.
Record
the sequence of indexes into 'indexes' that yields the subobject
we're
assigning to. Record the integer offsets of the constructor
indexes
we're assigning through into 'index_pos_hints'. After evaluating
the
initializer of the store expression, recompute 'valp' using
'indexes'
and using 'index_pos_hints' as hints.
(cxx_eval_bare_aggregate): Tweak comments. Use
get_or_insert_ctor_field
to recompute the constructor_elt pointer we're assigning through
after
evaluating each initializer.
gcc/testsuite/ChangeLog:
PR c++/94219
PR c++/94205
* g++.dg/cpp1y/constexpr-nsdmi3.C: New test.
* g++.dg/cpp1y/constexpr-nsdmi4.C: New test.
* g++.dg/cpp1y/constexpr-nsdmi5.C: New test.
* g++.dg/cpp1z/lambda-this5.C: New test.
More information about the Gcc-bugs
mailing list