[Bug libstdc++/94540] stack overflow populating std::vector<very large type>

["cvs-commit at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94540

--- Comment #1 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jonathan Wakely <redi@gcc.gnu.org>:

https://gcc.gnu.org/g:632183ddcc8f3aead8b4fc63c4ab59a42ef9ad00

commit r11-1464-g632183ddcc8f3aead8b4fc63c4ab59a42ef9ad00
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Wed Jun 17 22:49:06 2020 +0100

    libstdc++: Avoid stack overflow in std::vector (PR 94540)

    The std::__uninitialized_default_n algorithm used by std::vector creates
    an initial object as a local variable then copies that into the
    destination range. If the object is too large for the stack this
    crashes. We should create the first object directly into the
    destination and then copy it from there.

    This doesn't fix the bug for C++98, because in that case the initial
    value is created as a default argument of the vector constructor i.e. in
    the user's code, not inside libstdc++. We can't prevent that.

            PR libstdc++/94540
            * include/bits/stl_uninitialized.h
(__uninitialized_default_1<true>):
            Construct the first value at *__first instead of on the stack.
            (__uninitialized_default_n_1<true>): Likewise.
            Improve comments on several of the non-standard algorithms.
            *
testsuite/20_util/specialized_algorithms/uninitialized_default/94540.cc:
            New test.
            *
testsuite/20_util/specialized_algorithms/uninitialized_default_n/94540.cc:
            New test.
            *
testsuite/20_util/specialized_algorithms/uninitialized_value_construct/94540.cc:
            New test.
            *
testsuite/20_util/specialized_algorithms/uninitialized_value_construct_n/94540.cc:
            New test.
            * testsuite/23_containers/vector/cons/94540.cc: New test.