[Bug libstdc++/58338] New: Add noexcept to functions with a narrow contract

[Bug libstdc++/58338] New: Add noexcept to functions with a narrow contract

[glisse at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58338

            Bug ID: 58338
           Summary: Add noexcept to functions with a narrow contract
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: enhancement
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: glisse at gcc dot gnu.org

Hello,

the standard only requires a noexcept specifier on functions with a wide
contract, to allow some debug implementations of functions with a narrow
contract. However, it also explicitly gives permission to strengthen the
exception specification of non-virtual functions. I believe libstdc++ should
add noexcept whereever it can, since this is supposed to help with performance.

Functions like vector::front seem like good candidates. I wouldn't mind if the
debug version had a different exception specification, but that doesn't even
seem necessary since libstdc++ aborts instead of throwing.

https://groups.google.com/a/isocpp.org/d/msg/std-discussion/lkRyImxouC0/kZpWqI0MjXsJ

[Bug libstdc++/58338] Add noexcept to functions with a narrow contract

[daniel.kruegler at googlemail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58338

Daniel Krügler <daniel.kruegler at googlemail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |daniel.kruegler@googlemail.
                   |                            |com

--- Comment #1 from Daniel Krügler <daniel.kruegler at googlemail dot com> ---
I'm also very much in favor of this suggestion.
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Subject: [Bug libstdc++/58338] Add noexcept to functions with a narrow contract
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http://gcc.gnu.org/bugzilla/show_bug.cgi?idX338

--- Comment #2 from Paolo Carlini <paolo.carlini at oracle dot com> ---
... patches welcome!

[Bug libstdc++/58338] Add noexcept to functions with a narrow contract

[glisse at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58338

--- Comment #3 from Marc Glisse <glisse at gcc dot gnu.org> ---
Author: glisse
Date: Tue Sep 17 12:23:54 2013
New Revision: 202650

URL: http://gcc.gnu.org/viewcvs?rev=202650&root=gcc&view=rev
Log:
2013-09-17  Marc Glisse  <marc.glisse@inria.fr>

    PR libstdc++/58338
    * include/bits/stl_vector.h (vector::vector(),
    vector::vector(const allocator_type&)): Merge.
    (_Vector_impl::_Vector_impl(_Tp_alloc_type const&),
    _Vector_impl::_Vector_impl(_Tp_alloc_type&&),
    _Vector_impl::_M_swap_data,
    _Vector_base::_Vector_base(const allocator_type&),
    _Vector_base::_Vector_base(allocator_type&&),
    _Vector_base::_Vector_base(_Vector_base&&), _Vector_base::~_Vector_base,
    vector::vector(const allocator_type&), vector::operator[],
    vector::operator[] const, vector::front, vector::front const,
    vector::back, vector::back const, vector::pop_back,
    vector::_M_erase_at_end): Mark as noexcept.
    * include/debug/vector (vector::vector(const _Allocator&),
    vector::operator[], vector::operator[] const, vector::front,
    vector::front const, vector::back, vector::back const, vector::pop_back,
    _M_requires_reallocation, _M_update_guaranteed_capacity,
    _M_invalidate_after_nth): Mark as noexcept.
    * include/profile/vector (vector::vector(const _Allocator&),
    vector::operator[], vector::operator[] const, vector::front,
    vector::front const, vector::back, vector::back const): Mark as
    noexcept.
    (vector::vector(vector&&, const _Allocator&)): Remove wrong noexcept.
    * testsuite/23_containers/vector/requirements/dr438/assign_neg.cc:
    Adjust line number.
    * testsuite/23_containers/vector/requirements/dr438/
    constructor_1_neg.cc: Likewise.
    * testsuite/23_containers/vector/requirements/dr438/
    constructor_2_neg.cc: Likewise.
    * testsuite/23_containers/vector/requirements/dr438/insert_neg.cc:
    Likewise.

Modified:
    trunk/libstdc++-v3/ChangeLog
    trunk/libstdc++-v3/include/bits/stl_vector.h
    trunk/libstdc++-v3/include/debug/vector
    trunk/libstdc++-v3/include/profile/vector
   
trunk/libstdc++-v3/testsuite/23_containers/vector/requirements/dr438/assign_neg.cc
   
trunk/libstdc++-v3/testsuite/23_containers/vector/requirements/dr438/constructor_1_neg.cc
   
trunk/libstdc++-v3/testsuite/23_containers/vector/requirements/dr438/constructor_2_neg.cc
   
trunk/libstdc++-v3/testsuite/23_containers/vector/requirements/dr438/insert_neg.cc

[Bug libstdc++/58338] Add noexcept to functions with a narrow contract

[glisse at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58338

--- Comment #4 from Marc Glisse <glisse at gcc dot gnu.org> ---
Author: glisse
Date: Wed Sep 18 11:21:51 2013
New Revision: 202699

URL: http://gcc.gnu.org/viewcvs?rev=202699&root=gcc&view=rev
Log:
2013-09-18  Marc Glisse  <marc.glisse@inria.fr>

    PR libstdc++/58338
    * include/bits/list.tcc (_List_base::_M_clear, list::erase): Mark as
    noexcept.
    * include/bits/stl_list.h (_List_iterator) [_List_iterator,
    _M_const_cast, operator*, operator->, operator++, operator--,
    operator==, operator!=]: Likewise.
    (_List_const_iterator) [_List_const_iterator, _M_const_cast, operator*,
    operator->, operator++, operator--, operator==, operator!=]: Likewise.
    (operator==(const _List_iterator&, const _List_const_iterator&),
    operator!=(const _List_iterator&, const _List_const_iterator&)):
    Likewise.
    (_List_impl) [_List_impl(const _Node_alloc_type&),
    _List_impl(_Node_alloc_type&&)]: Likewise.
    (_List_base) [_M_put_node, _List_base(const _Node_alloc_type&),
    _List_base(_List_base&&), _M_clear, _M_init]: Likewise.
    (list) [list(), list(const allocator_type&)]: Merge.
    (list) [list(const allocator_type&), front, back, pop_front, pop_back,
    erase, _M_erase]: Mark as noexcept.
    * include/debug/list (list) [list(const _Allocator&), front, back,
    pop_front, pop_back, _M_erase, erase]: Likewise.
    * include/profile/list (list) [list(const _Allocator&), front, back,
    pop_front, pop_back, erase]: Likewise.
    * testsuite/23_containers/list/requirements/dr438/assign_neg.cc:
    Adjust line number.
    * testsuite/23_containers/list/requirements/dr438/constructor_1_neg.cc:
    Likewise.
    * testsuite/23_containers/list/requirements/dr438/constructor_2_neg.cc:
    Likewise.
    * testsuite/23_containers/list/requirements/dr438/insert_neg.cc:
    Likewise.

Modified:
    trunk/libstdc++-v3/ChangeLog
    trunk/libstdc++-v3/include/bits/list.tcc
    trunk/libstdc++-v3/include/bits/stl_list.h
    trunk/libstdc++-v3/include/debug/list
    trunk/libstdc++-v3/include/profile/list
   
trunk/libstdc++-v3/testsuite/23_containers/list/requirements/dr438/assign_neg.cc
   
trunk/libstdc++-v3/testsuite/23_containers/list/requirements/dr438/constructor_1_neg.cc
   
trunk/libstdc++-v3/testsuite/23_containers/list/requirements/dr438/constructor_2_neg.cc
   
trunk/libstdc++-v3/testsuite/23_containers/list/requirements/dr438/insert_neg.cc

[Bug libstdc++/58338] Add noexcept to functions with a narrow contract

[glisse at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58338

--- Comment #5 from Marc Glisse <glisse at gcc dot gnu.org> ---
Author: glisse
Date: Wed Sep 18 18:31:01 2013
New Revision: 202716

URL: http://gcc.gnu.org/viewcvs?rev=202716&root=gcc&view=rev
Log:
2013-09-18  Marc Glisse  <marc.glisse@inria.fr>

    PR libstdc++/58338
    * include/bits/stl_iterator.h (__normal_iterator) [__normal_iterator,
    _M_const_cast, operator*, operator->, operator++, operator--,
    operator[], operator+=, operator+, operator-=, operator-, base]:
    Mark as noexcept.
    (operator==(const __normal_iterator&, const __normal_iterator&),
    operator!=(const __normal_iterator&, const __normal_iterator&),
    operator<(const __normal_iterator&, const __normal_iterator&),
    operator>(const __normal_iterator&, const __normal_iterator&),
    operator<=(const __normal_iterator&, const __normal_iterator&),
    operator>=(const __normal_iterator&, const __normal_iterator&),
    operator-(const __normal_iterator&, const __normal_iterator&),
    operator+(difference_type, const __normal_iterator&)): Likewise.
    * include/bits/stl_list.h (list) [splice, _M_check_equal_allocators]:
    Likewise.
    (list::_M_check_equal_allocators): Abort instead of throwing.
    * include/debug/array (array) [operator[], front, back]: Mark as
    noexcept.
    * include/profile/array (array) [operator[], front, back]: Likewise.
    * include/std/array (array) [operator[], front, back]: Likewise.
    * include/debug/list (list::splice): Likewise.
    * include/profile/list (list::splice): Likewise.
    * testsuite/23_containers/list/operations/5.cc: Remove file.
    * testsuite/23_containers/list/operations/5.h: Likewise.

Removed:
    trunk/libstdc++-v3/testsuite/23_containers/list/operations/5.cc
    trunk/libstdc++-v3/testsuite/23_containers/list/operations/5.h
Modified:
    trunk/libstdc++-v3/ChangeLog
    trunk/libstdc++-v3/include/bits/stl_iterator.h
    trunk/libstdc++-v3/include/bits/stl_list.h
    trunk/libstdc++-v3/include/debug/array
    trunk/libstdc++-v3/include/debug/list
    trunk/libstdc++-v3/include/profile/array
    trunk/libstdc++-v3/include/profile/list
    trunk/libstdc++-v3/include/std/array

[Bug libstdc++/58338] Add noexcept to functions with a narrow contract

[glisse at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58338

--- Comment #6 from Marc Glisse <glisse at gcc dot gnu.org> ---
Author: glisse
Date: Thu Sep 19 11:40:29 2013
New Revision: 202737

URL: http://gcc.gnu.org/viewcvs?rev=202737&root=gcc&view=rev
Log:
2013-09-19  Marc Glisse  <marc.glisse@inria.fr>

    PR libstdc++/58338
    * include/bits/stl_tree.h (_Rb_tree_node_base) [_S_minimum, _S_maximum]:
    Mark as noexcept.
    (_Rb_tree_iterator) [_Rb_tree_iterator, operator*, operator->,
    operator++, operator--, operator==, operator!=]: Likewise.
    (_Rb_tree_const_iterator) [_Rb_tree_const_iterator, _M_const_cast,
    operator*, operator->, operator++, operator--, operator==, operator!=]:
    Likewise.
    (operator==(const _Rb_tree_iterator&, const _Rb_tree_const_iterator&),
    operator!=(const _Rb_tree_iterator&, const _Rb_tree_const_iterator&)):
    Likewise.
    (_Rb_tree) [_M_put_node, _M_destroy_node, _M_root, _M_leftmost,
    _M_rightmost, _M_begin, _M_end, _S_left, _S_right, _S_minimum,
    _S_maximum]: Likewise.
    * include/debug/string (basic_string) [basic_string(const _Allocator&),
    shrink_to_fit, operator[], pop_back]: Likewise.
    * include/ext/vstring.h (__versa_string) [_M_limit, _M_disjunct,
    _M_ibegin, _M_iend, __versa_string(const _Alloc&),
    operator=(__versa_string&&), shrink_to_fit, operator[], front,
    back, assign(__versa_string&&), swap]: Likewise.
    (__versa_string) [__versa_string(), __versa_string(const _Alloc&)]:
    Merge.

Modified:
    trunk/libstdc++-v3/ChangeLog
    trunk/libstdc++-v3/include/bits/stl_tree.h
    trunk/libstdc++-v3/include/debug/string
    trunk/libstdc++-v3/include/ext/vstring.h

[Bug libstdc++/58338] Add noexcept to functions with a narrow contract

[glisse at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58338

--- Comment #7 from Marc Glisse <glisse at gcc dot gnu.org> ---
Author: glisse
Date: Fri Sep 20 15:50:09 2013
New Revision: 202781

URL: http://gcc.gnu.org/viewcvs?rev=202781&root=gcc&view=rev
Log:
2013-09-20  Marc Glisse  <marc.glisse@inria.fr>

    PR libstdc++/58338
    * include/bits/allocator.h (__alloc_swap::_S_do_it,
    __shrink_to_fit_aux::_S_do_it): Mark as noexcept.
    * include/bits/basic_string.h (basic_string::_Rep) [_S_empty_rep,
    _M_is_leaked, _M_is_shared, _M_set_leaked, _M_set_sharable,
    _M_set_length_and_sharable, _M_dispose]: Likewise.
    (basic_string::_Alloc_hider::_Alloc_hider): Likewise.
    (basic_string) [_M_data, _M_rep, _M_ibegin, _M_iend, _M_limit,
    _M_disjunct, _M_copy, _M_move, _M_assign, _S_copy_chars, _S_compare,
    _S_empty_rep, shrink_to_fit, operator[] const, front const, back const]:
    Likewise.
    [clear]: Link to PR 56166.
    [swap]: Link to PR 58265.
    * include/bits/stl_deque.h (_Deque_iterator) [_S_buffer_size,
    _Deque_iterator, _M_const_cast, operator*, operator->, operator++,
    operator--, operator+=, operator+, operator-=, operator-, operator[],
    _M_set_node]: Mark as noexcept.
    (operator==(const _Deque_iterator&, const _Deque_iterator&),
    operator!=(const _Deque_iterator&, const _Deque_iterator&),
    operator<(const _Deque_iterator&, const _Deque_iterator&),
    operator>(const _Deque_iterator&, const _Deque_iterator&),
    operator<=(const _Deque_iterator&, const _Deque_iterator&),
    operator>=(const _Deque_iterator&, const _Deque_iterator&),
    operator-(const _Deque_iterator&, const _Deque_iterator&),
    operator+(ptrdiff_t, const _Deque_iterator&)): Likewise.
    (_Deque_base) [_Deque_base(const allocator_type&)]: Add missing call to
    _M_initialize_map.
    [~_Deque_base, _M_deallocate_node, _M_deallocate_map, _M_destroy_nodes]:
    Mark as noexcept.
    (_Deque_base::_Deque_impl) [_Deque_impl(const _Tp_alloc_type&),
    _Deque_impl(_Tp_alloc_type&&)]: Likewise.
    (deque) [_S_buffer_size, operator=(deque&&), shrink_to_fit, operator[],
    front, back, pop_front, pop_back, swap]: Likewise.
    [deque(), deque(const allocator_type&)]: Merge.
    * include/debug/deque (deque) [operator=(deque&&), shrink_to_fit,
    operator[], front, back, pop_front, pop_back, swap]: Mark as noexcept.
    * include/profile/deque (deque) [operator=(deque&&), operator[], front,
    back, pop_front, pop_back, swap]: Likewise.
    * testsuite/23_containers/deque/requirements/dr438/assign_neg.cc:
    Adjust line number.
    * testsuite/23_containers/deque/requirements/dr438/constructor_1_neg.cc:
    Likewise.
    * testsuite/23_containers/deque/requirements/dr438/constructor_2_neg.cc:
    Likewise.
    * testsuite/23_containers/deque/requirements/dr438/insert_neg.cc:
    Likewise.

Modified:
    trunk/libstdc++-v3/ChangeLog
    trunk/libstdc++-v3/include/bits/allocator.h
    trunk/libstdc++-v3/include/bits/basic_string.h
    trunk/libstdc++-v3/include/bits/stl_deque.h
    trunk/libstdc++-v3/include/debug/deque
    trunk/libstdc++-v3/include/profile/deque
   
trunk/libstdc++-v3/testsuite/23_containers/deque/requirements/dr438/assign_neg.cc
   
trunk/libstdc++-v3/testsuite/23_containers/deque/requirements/dr438/constructor_1_neg.cc
   
trunk/libstdc++-v3/testsuite/23_containers/deque/requirements/dr438/constructor_2_neg.cc
   
trunk/libstdc++-v3/testsuite/23_containers/deque/requirements/dr438/insert_neg.cc

[Bug libstdc++/58338] Add noexcept to functions with a narrow contract

[glisse at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58338

--- Comment #8 from Marc Glisse <glisse at gcc dot gnu.org> ---
Author: glisse
Date: Tue Sep 24 10:07:32 2013
New Revision: 202861

URL: http://gcc.gnu.org/viewcvs?rev=202861&root=gcc&view=rev
Log:
2013-09-24  Marc Glisse  <marc.glisse@inria.fr>

    PR libstdc++/58338
    PR libstdc++/56166
    * include/bits/basic_string.h (basic_string)
    [basic_string(basic_string&&)]: Make the noexcept conditional.
    [operator=(basic_string&&), assign(basic_string&&)]: Link to PR 58265.
    [begin(), end(), rbegin(), rend(), clear]: Remove noexcept.
    [pop_back]: Comment on the lack of noexcept.
    * include/debug/string (basic_string) [basic_string(const _Allocator&),
    basic_string(basic_string&&), begin(), end(), rbegin(), rend(), clear,
    operator[](size_type), pop_back]: Comment out noexcept, until vstring
    replaces basic_string.

Modified:
    trunk/libstdc++-v3/ChangeLog
    trunk/libstdc++-v3/include/bits/basic_string.h
    trunk/libstdc++-v3/include/debug/string

[Bug libstdc++/58338] Add noexcept to functions with a narrow contract

[glisse at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58338

--- Comment #9 from Marc Glisse <glisse at gcc dot gnu.org> ---
Author: glisse
Date: Wed Sep 25 20:28:12 2013
New Revision: 202924

URL: http://gcc.gnu.org/viewcvs?rev=202924&root=gcc&view=rev
Log:
2013-09-25  Marc Glisse  <marc.glisse@inria.fr>

    PR libstdc++/58338
    * include/bits/forward_list.h (_Fwd_list_node_base::_M_transfer_after):
    Mark as noexcept.
    (_Fwd_list_iterator) [_Fwd_list_iterator, operator*, operator->,
    operator++, operator==, operator!=, _M_next]: Likewise.
    (_Fwd_list_const_iterator) [_Fwd_list_const_iterator, operator*,
    operator->, operator++, operator==, operator!=, _M_next]: Likewise.
    (operator==(const _Fwd_list_iterator&, const _Fwd_list_const_iterator&),
    operator!=(const _Fwd_list_iterator&, const _Fwd_list_const_iterator&)):
    Likewise.
    * include/bits/hashtable_policy.h (_Hash_node_base::_Hash_node_base,
    _Hash_node::_M_next, _Node_iterator_base::_Node_iterator_base,
    _Node_iterator_base::_M_incr, operator==(const _Node_iterator_base&,
    const _Node_iterator_base&), operator!=(const _Node_iterator_base&,
    const _Node_iterator_base&)): Likewise.
    (_Node_iterator) [_Node_iterator, operator*, operator->, operator++]:
    Likewise.
    (_Node_const_iterator) [_Node_const_iterator, operator*, operator->,
    operator++]: Likewise.
    * include/debug/safe_iterator.h (_Safe_iterator) [_Safe_iterator,
    operator=, operator*, operator->, operator++, operator--, operator[],
    operator+=, operator+, operator-=, operator-, base, operator _Iterator]:
    Likewise.
    (operator==(const _Safe_iterator&, const _Safe_iterator&),
    operator!=(const _Safe_iterator&, const _Safe_iterator&),
    operator<(const _Safe_iterator&, const _Safe_iterator&),
    operator<=(const _Safe_iterator&, const _Safe_iterator&),
    operator>(const _Safe_iterator&, const _Safe_iterator&),
    operator>=(const _Safe_iterator&, const _Safe_iterator&),
    operator-(const _Safe_iterator&, const _Safe_iterator&),
    operator+(difference_type, const _Safe_iterator&)): Likewise.
    * include/profile/iterator_tracker.h (__iterator_tracker)
    [__iterator_tracker, base, operator _Iterator, operator->, operator++,
    operator--, operator=, operator*, operator[], operator+=, operator+,
    operator-=, operator-]: Likewise.
    (operator==(const __iterator_tracker&, const __iterator_tracker&),
    operator!=(const __iterator_tracker&, const __iterator_tracker&),
    operator<(const __iterator_tracker&, const __iterator_tracker&),
    operator<=(const __iterator_tracker&, const __iterator_tracker&),
    operator>(const __iterator_tracker&, const __iterator_tracker&),
    operator>=(const __iterator_tracker&, const __iterator_tracker&),
    operator-(const __iterator_tracker&, const __iterator_tracker&),
    operator+(difference_type, const __iterator_tracker&)): Likewise.

Modified:
    trunk/libstdc++-v3/ChangeLog
    trunk/libstdc++-v3/include/bits/forward_list.h
    trunk/libstdc++-v3/include/bits/hashtable_policy.h
    trunk/libstdc++-v3/include/debug/safe_iterator.h
    trunk/libstdc++-v3/include/profile/iterator_tracker.h

[Bug libstdc++/58338] Add noexcept to functions with a narrow contract

[bredelin at ucla dot edu]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58338

bredelin at ucla dot edu changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bredelin at ucla dot edu

--- Comment #10 from bredelin at ucla dot edu ---
It seems that these changes (see Sep 17th) also made the default constructor
explicit.  While this does follow the standard, it is the subject of this
defect report:

http://cplusplus.github.io/LWG/lwg-active.html#2193

Was this change intentional?

[Bug libstdc++/58338] Add noexcept to functions with a narrow contract

[glisse at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58338

--- Comment #11 from Marc Glisse <glisse at gcc dot gnu.org> ---
(In reply to bredelin from comment #10)
> Was this change intentional?

See:
http://gcc.gnu.org/ml/gcc-patches/2013-09/msg01101.html
and Paolo's reply.

[Bug libstdc++/58338] Add noexcept to functions with a narrow contract

[glisse at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58338

--- Comment #12 from Marc Glisse <glisse at gcc dot gnu.org> ---
(In reply to bredelin from comment #10)
> http://cplusplus.github.io/LWG/lwg-active.html#2193

I suggest you open a separate bugzilla PR for this. Before my patch we were
already inconsistent about it.

[Bug libstdc++/58338] Add noexcept to functions with a narrow contract

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58338

--- Comment #13 from Paolo Carlini <paolo.carlini at oracle dot com> ---
In any case I see that the issue with explicit instantiation is recorded in
2193. Let's see what happens in EWG.

[Bug libstdc++/58338] Add noexcept to functions with a narrow contract

[glisse at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58338

--- Comment #14 from Marc Glisse <glisse at gcc dot gnu.org> ---
Author: glisse
Date: Sat Feb 22 10:24:11 2014
New Revision: 208041

URL: http://gcc.gnu.org/viewcvs?rev=208041&root=gcc&view=rev
Log:
2014-02-22  Marc Glisse  <marc.glisse@inria.fr>

    PR libstdc++/60308
    * include/bits/stl_deque.h (_Deque_base::_Deque_base(const
    allocator_type&)): Remove redundant call to _M_initialize_map.
    (deque::deque(const allocator_type&)): Initialize _Base with a
    constructor that calls _M_initialize_map.

    Partial revert:

    2013-09-20  Marc Glisse  <marc.glisse@inria.fr>
    PR libstdc++/58338
    (_Deque_base) [_Deque_base(const allocator_type&)]: Add missing call to
    _M_initialize_map.

Modified:
    trunk/libstdc++-v3/ChangeLog
    trunk/libstdc++-v3/include/bits/stl_deque.h

[Bug libstdc++/58338] Add noexcept to functions with a narrow contract

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58338

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |WAITING

--- Comment #15 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Is there any low-hanging fruit left here? Can we close this?

We should accept any patches that strengthen noexcept guarantees elsewhere in
the library, we don't need a PR to do so.

[Bug libstdc++/58338] Add noexcept to functions with a narrow contract

[glisse at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58338

Marc Glisse <glisse at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|WAITING                     |RESOLVED

--- Comment #16 from Marc Glisse <glisse at gcc dot gnu.org> ---
No idea if there are low hanging fruits. I think the original idea was to get
consensus on the idea to add noexcept in various places, and this seems well
accepted now.
At some point (back when I thought I would have enough free time) my plan was
to implement some form of noexcept(auto) as an extension, I think most of the
remaining places where we may want to add noexcept would benefit from that. The
effort and risk in working around the lack of this feature (writing 10+ lines
of nexcept(...), is_nothrow_*, etc) make it not worth it to me.

[Bug libstdc++/58338] Add noexcept to functions with a narrow contract

[dangelog at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58338

Giuseppe D'Angelo <dangelog at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |dangelog at gmail dot com

--- Comment #17 from Giuseppe D'Angelo <dangelog at gmail dot com> ---
Hi,

How does all of this intersect with the Lakos' Rule (cf. the very recent P2837
and P2861)? I get that implementations have the freedom of strenghtening the
noexcept contract; but is this patch following some specific libstdc++ policy
(documented somewhere) -- such as, if a precondition violation is detected,
libstdc++ just abort()s the process, so technically speaking, it never throws?

[Bug libstdc++/58338] Add noexcept to functions with a narrow contract

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58338

--- Comment #18 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Our precondition checks never throw, so those functions never throw.