LWG3759 ranges::rotate_copy should use std::move
This has been one in the initial version (D127211).
Reviewed By: #libc, ldionne
Differential Revision: https://reviews.llvm.org/D142813
The removal of operator!= in this header will be done in a separate
commit.
Note in the synopsis of P1614R2 there is a constexpr
template<class BiIter>
constexpr auto operator<=>(const sub_match<BiIter>& lhs, const sub_match<BiIter>& rhs);
In the implementation of P1614R2 there isn't a constexpr
template<class BiIter>
auto operator<=>(const sub_match<BiIter>& lhs, const sub_match<BiIter>& rhs);
There doesn't seem to be an LWG-issue, but it was fixed in the Standard
by removing the constexpr in b050fd474f11441942c88ef69b8622c8036656ac.
Implements part of:
- P1614R2 The Mothership has Landed
Reviewed By: #libc, ldionne
Differential Revision: https://reviews.llvm.org/D132310
As obvious from the paper's title this is an LWG issue and thus retroactively
applied to C++20. This change may the output for certain code points:
1 Considers 8477 extra codepoints as having a width 2 (as of Unicode 15)
(mostly Tangut Ideographs)
2 Change the width of 85 unassigned code points from 2 to 1
3 Change the width of 8 codepoints (in the range U+3248 CIRCLED NUMBER
TEN ON BLACK SQUARE ... U+324F CIRCLED NUMBER EIGHTY ON BLACK
SQUARE) from 2 to 1, because it seems questionable to make an exception
for those without input from Unicode
Note that libc++ already uses Unicode 15, while the Standard requires Unicode 12.
(The last time I checked MSVC STL used Unicode 14.)
So in practice the only notable change is item 3.
Implements
P2675 LWG3780: The Paper
format's width estimation is too approximate and not forward compatible
Benchmark before these changes
--------------------------------------------------------------------
Benchmark Time CPU Iterations
--------------------------------------------------------------------
BM_ascii_text<char> 3928 ns 3928 ns 178131
BM_unicode_text<char> 75231 ns 75230 ns 9158
BM_cyrillic_text<char> 59837 ns 59834 ns 11529
BM_japanese_text<char> 39842 ns 39832 ns 17501
BM_emoji_text<char> 3931 ns 3930 ns 177750
BM_ascii_text<wchar_t> 4024 ns 4024 ns 174190
BM_unicode_text<wchar_t> 63756 ns 63751 ns 11136
BM_cyrillic_text<wchar_t> 44639 ns 44638 ns 15597
BM_japanese_text<wchar_t> 34425 ns 34424 ns 20283
BM_emoji_text<wchar_t> 3937 ns 3937 ns 177684
Benchmark after these changes
--------------------------------------------------------------------
Benchmark Time CPU Iterations
--------------------------------------------------------------------
BM_ascii_text<char> 3914 ns 3913 ns 178814
BM_unicode_text<char> 70380 ns 70378 ns 9694
BM_cyrillic_text<char> 51889 ns 51877 ns 13488
BM_japanese_text<char> 41707 ns 41705 ns 16723
BM_emoji_text<char> 3908 ns 3907 ns 177912
BM_ascii_text<wchar_t> 3949 ns 3948 ns 177525
BM_unicode_text<wchar_t> 64591 ns 64587 ns 10649
BM_cyrillic_text<wchar_t> 44089 ns 44078 ns 15721
BM_japanese_text<wchar_t> 39369 ns 39367 ns 17779
BM_emoji_text<wchar_t> 3936 ns 3934 ns 177821
Benchmarks without "if(__code_point < (__entries[0] >> 14))"
--------------------------------------------------------------------
Benchmark Time CPU Iterations
--------------------------------------------------------------------
BM_ascii_text<char> 3922 ns 3922 ns 178587
BM_unicode_text<char> 94474 ns 94474 ns 7351
BM_cyrillic_text<char> 69202 ns 69200 ns 10157
BM_japanese_text<char> 42735 ns 42692 ns 16382
BM_emoji_text<char> 3920 ns 3919 ns 178704
BM_ascii_text<wchar_t> 3951 ns 3950 ns 177224
BM_unicode_text<wchar_t> 81003 ns 80988 ns 8668
BM_cyrillic_text<wchar_t> 57020 ns 57018 ns 12048
BM_japanese_text<wchar_t> 39695 ns 39687 ns 17582
BM_emoji_text<wchar_t> 3977 ns 3976 ns 176479
This optimization does carry its weight for the Unicode and Cyrillic
test. For the Japanese tests the gains are minor and for emoji it seems
to have no effect.
Reviewed By: ldionne, tahonermann, #libc
Differential Revision: https://reviews.llvm.org/D144499
The __cpp_lib_format_ranges feature-test macro only depends on P2286R8
and P2585R0. Note since LWG3750 only affects these two C++23 papers
there is nothing to do for older language versions.
(The __cpp_lib_format feature-test macro depends on the incomplete
formatting for chrono. So this part can't be marked as complete yet.)
This completes
- P2286R8 Formatting ranges
- P2585R0 Improving default container formatting
This partly implements
- LWG3750 Too many papers bump __cpp_lib_format
Reviewed By: #libc, ldionne
Differential Revision: https://reviews.llvm.org/D147880
LWG3720 Restrict the valid types of arg-id for width and precision in
std-format-spec
Depends on D144325
Reviewed By: #libc, ldionne
Differential Revision: https://reviews.llvm.org/D144326
Since stacktrace header is WIP and it's not sure that will be done
before LLVM17 update the documentation. When the header is implemented
implementing the formatter is trivial, so that can be done quickly
afterwards.
Implements parts of:
- P2693R1 Formatting thread::id and stacktrace
Reviewed By: #libc, ldionne
Differential Revision: https://reviews.llvm.org/D144331
This LWG issue is based on the discussion regarding
P2733R3 Fix handling of empty specifiers in std::format
This paper was disussed and changed a few times in LEWG during the
Issaquah meeting. The paper was not voted in, instead LEWG asked for
a DR against C++26.
This LWG issue contains the direction voted by LEWG. This issue has not
been voted in yet. However it fixes some of the defencies on the
container based formatting. Without this fix the range-default-formatter
for strings looks bad when used in containers.
The changes of this issue match the intended changes of P27333.
type fmt before after (if changed)
---------------------------------------------------------------
char {} a
char {:?} 'a'
array<char, 1> {} ['a']
array<char, 1> {::} [a]
array<char, 1> {::c} [a]
array<char, 1> {::?} ['a']
map<char, char> {} {a: a} -> {'a': 'a'}
map<char, char> {::} {'a': 'a'}
set<char> {} {'a'}
set<char> {::} {a}
set<char> {::c} {a}
set<char> {::?} {'a'}
tuple<char> {} ('a')
stack<char> {} ['a']
stack<char> {::} [a]
stack<char> {::c} [a]
stack<char> {::?} ['a']
array<array<char, 1>, 1> {} [[a]] -> {'a': 'a'}
array<array<char, 1>, 1> {::} [['a']]
array<array<char, 1>, 1> {:::} [[a]]
array<array<char, 1>, 1> {:::c} [[a]]
array<array<char, 1>, 1> {:::?} [['a']]
array<tuple<char>, 1> {} [(a)] -> [('a')]
tuple<tuple<char>> {} ((a)) -> (('a'))
tuple<array<char, 1>> {} ([a]) -> (['a'])
Note the optimization text as mentioned in the tuple formatter can't be
done. The call to parse may affect the formatter so its state needs to
be preserved.
Reviewed By: ldionne, #libc, EricWF
Differential Revision: https://reviews.llvm.org/D145847
LWG3842 Unclear wording for precision in chrono-format-spec
Note there is nothing to do, the issue clarifies the wording in the Standard.
The new wording matches my interpretation of the previous wording and this has
already been implemented in libc++.
Reviewed By: #libc, ldionne
Differential Revision: https://reviews.llvm.org/D144328
Implements parts of P1614R2: `operator<=>` for `map` and `multimap`
Reviewed By: #libc, philnik
Spies: philnik, libcxx-commits, yaxunl
Differential Revision: https://reviews.llvm.org/D145976
LWG3358 §[span.cons] is mistaken that to_address can throw
Since last - first has to throw tests are added to make sure this always
happens.
Depends on D142808
Reviewed By: #libc, ldionne
Differential Revision: https://reviews.llvm.org/D142843
LWG3839 range_formatter's set_separator, set_brackets, and
underlying functions should be noexcept
Adds tests for:
template<ranges::input_range R, class charT>
struct range-default-formatter<range_format::sequence, R, charT>
These were missing, the format functions tests for the sequences
are already present.
Reviewed By: #libc, ldionne
Differential Revision: https://reviews.llvm.org/D144286
https://wg21.link/LWG2444 updated the comparison complexity of
std:sort_heap to be at most 2N log (N) where N == last - first. In the
current implementation, we invoke __pop_heap exactly N-1 times. In each
call to __pop_heap, we first go down the heap from first to possibly
last in the function __floyd_sift_down. Then, we possibly go back up in
the function __sift_up.
In the function __floyd_sift_down, there is loop in which one comparison
is made in each iteration. The loop runs till __child becomes greater
than (__len - 2) / 2. __child starts at 0 and it is at least set to 2 *
__child + 1 on each iteration. Thus, after k iterations, __child will
be at least 2^k - 1. After log(N) iterations, __child >= 2^(log(N)) -
1 = N - 1 > (__len - 2) / 2. This means that the while loop in the
function __floyd_sift_down would perform at most log(N) comparisons on
each invocation.
In the function __sift_up, there is one comparison made that will almost
always occur. After that there is a do-while loop. The comparison
function is invoked once in each iteration. In the worst case, the loop
will run till __len goes down to zero. It can start from (N-3)/2. In
each iteration, __len goes down to (__len-1) / 2. After k iterations,
__len will be at most (N - 2^(k+1) -1) / 2^(k+1). Thus, __len will
become when (N-2^(k+1)-1) < 2^(k+1) i.e. N < 2^(k+2) + 1. This means
at most log(N) - 1 iterations for the loop. So in total at most log(N)
comparison will be performed in __sift_up.
So overall for each iteration of the loop in __pop_heap, there will at
most 2 log(N) comparisons. So, the total number of comparisons is
at most 2 N log(N).
We also updated the test sort.heap/complexity.pass.cpp to test for the
number of operations.
Differential Revision: https://reviews.llvm.org/D144538
LWG3103 Errors in taking subview of span should be ill-formed where possible
Note that the real work was already done before, including tests.
Reviewed By: #libc, ldionne
Differential Revision: https://reviews.llvm.org/D143432
The `basic_string_view` constructor accepting a contiguous range rejects
converting between `basic_string_view` even when only the trait types vary.
This prevents conversions for converting from `basic_string_view<C, T1>` and
`basic_string<C, T1, A>` to `basic_string_view<C, T2>`. Recently, this
constructor was made `explicit`, so there's no reason to really forbid this
conversion anymore.
Relax the restriction that the trait types need to match in this constructor.
Differential Revision: https://reviews.llvm.org/D143972
Partially implements:
- P1361 Integration of chrono with text formatting
- P2372 Fixing locale handling in chrono formatters
- P1466 Miscellaneous minor fixes for chrono
Depends on D137022
Reviewed By: ldionne, #libc
Differential Revision: https://reviews.llvm.org/D139771
Instead of destroying the object with allocator::destroy, we must
call its destructor directly. As a fly-by also mark LWG3008 as
fixed since it is handled by our implementation.
This was pointed out by Tim Song in https://reviews.llvm.org/D140913.
Differential Revision: https://reviews.llvm.org/D143791
The implementation makes use of the freedom added by LWG 3410. We have
two variants of this algorithm:
* a fast path for random access iterators: This fast path computes the
maximum number of loop iterations up-front and does not compare the
iterators against their limits on every loop iteration.
* A basic implementation for all other iterators: This implementation
compares the iterators against their limits in every loop iteration.
However, it still takes advantage of the freedom added by LWG 3410 to
avoid unnecessary additional iterator comparisons, as originally
specified by P1614R2.
https://godbolt.org/z/7xbMEen5e shows the benefit of the fast path:
The hot loop generated of `lexicographical_compare_three_way3` is
more tight than for `lexicographical_compare_three_way1`. The added
benchmark illustrates how this leads to a 30% - 50% performance
improvement on integer vectors.
Implements part of P1614R2 "The Mothership has Landed"
Fixes LWG 3410 and LWG 3350
Differential Revision: https://reviews.llvm.org/D131395
