[libc++][RFC] Always define internal feature test macros (#89178)

Currently, the library-internal feature test macros are only defined if
the feature is not available, and always have the prefix
`

[libc++][RFC] Always define internal feature test macros (#89178)

Currently, the library-internal feature test macros are only defined if
the feature is not available, and always have the prefix
`_LIBCPP_HAS_NO_`. This patch changes that, so that they are always
defined and have the prefix `_LIBCPP_HAS_` instead. This changes the
canonical use of these macros to `#if _LIBCPP_HAS_FEATURE`, which means
that using an undefined macro (e.g. due to a missing include) is
diagnosed now. While this is rather unlikely currently, a similar change
in `<__configuration/availability.h>` caught a few bugs. This also
improves readability, since it removes the double-negation of `#ifndef
_LIBCPP_HAS_NO_FEATURE`.

The current patch only touches the macros defined in `<__config>`. If
people are happy with this approach, I'll make a follow-up PR to also
change the macros defined in `<__config_site>`.

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[libc++] Clean up includes of <__assert> (#80091)

Originally, we used __libcpp_verbose_abort to handle assertion failures.
That function was declared from all public headers. Since we don't use
th

[libc++] Clean up includes of <__assert> (#80091)

Originally, we used __libcpp_verbose_abort to handle assertion failures.
That function was declared from all public headers. Since we don't use
that mechanism anymore, we don't need to declare __libcpp_verbose_abort
from all public headers, and we can clean up a lot of unnecessary
includes.

This patch also moves the definition of the various assertion categories
to the <__assert> header, since we now rely on regular IWYU for these
assertion macros.

rdar://105510916

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[libc++][hardening] Categorize more assertions. (#75918)

Also introduce `_LIBCPP_ASSERT_PEDANTIC` for assertions violating which
results in a no-op or other benign behavior, but which may neverthel

[libc++][hardening] Categorize more assertions. (#75918)

Also introduce `_LIBCPP_ASSERT_PEDANTIC` for assertions violating which
results in a no-op or other benign behavior, but which may nevertheless
indicate a bug in the invoking code.

show more ...

[libc++][hardening][NFC] Introduce `_LIBCPP_ASSERT_UNCATEGORIZED`.

Replace most uses of `_LIBCPP_ASSERT` with
`_LIBCPP_ASSERT_UNCATEGORIZED`.

This is done as a prerequisite to introducing hardened

[libc++][hardening][NFC] Introduce `_LIBCPP_ASSERT_UNCATEGORIZED`.

Replace most uses of `_LIBCPP_ASSERT` with
`_LIBCPP_ASSERT_UNCATEGORIZED`.

This is done as a prerequisite to introducing hardened mode to libc++.
The idea is to make enabling assertions an opt-in with (somewhat)
fine-grained controls over which categories of assertions are enabled.
The vast majority of assertions are currently uncategorized; the new
macro will allow turning on `_LIBCPP_ASSERT` (the underlying mechanism
for all kinds of assertions) without enabling all the uncategorized
assertions (in the future; this patch preserves the current behavior).

Differential Revision: https://reviews.llvm.org/D153816

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[NFC][libc++] Formats granularized charconv.

Reviewed By: #libc, Mordante

Differential Revision: https://reviews.llvm.org/D146153

[libc++][NFC] Replace _LIBCPP_STD_VER > x with _LIBCPP_STD_VER >= x

This change is almost fully mechanical. The only interesting change is in `generate_feature_test_macro_components.py` to generate

[libc++][NFC] Replace _LIBCPP_STD_VER > x with _LIBCPP_STD_VER >= x

This change is almost fully mechanical. The only interesting change is in `generate_feature_test_macro_components.py` to generate `_LIBCPP_STD_VER >=` instead. To avoid churn in the git-blame this commit should be added to the `.git-blame-ignore-revs` once committed.

Reviewed By: ldionne, var-const, #libc

Spies: jloser, libcxx-commits, arichardson, arphaman, wenlei

Differential Revision: https://reviews.llvm.org/D143962

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[libc++] Implements constexpr <charconv>.

Implements:
- P2291R3 Add Constexpr Modifiers to Functions to_chars and from_chars for
Integral Types in <charconv> Header

Reviewed By: #libc, ldionne

D

[libc++] Implements constexpr <charconv>.

Implements:
- P2291R3 Add Constexpr Modifiers to Functions to_chars and from_chars for
Integral Types in <charconv> Header

Reviewed By: #libc, ldionne

Differential Revision: https://reviews.llvm.org/D131317

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[libc++] Make charconv require C++17 or later.

Implementing the paper
P2291R3 Add Constexpr Modifiers to Functions to_chars and from_chars for
Integral Types in <charconv> Header

Gives issu

[libc++] Make charconv require C++17 or later.

Implementing the paper
P2291R3 Add Constexpr Modifiers to Functions to_chars and from_chars for
Integral Types in <charconv> Header

Gives issues in language versions prior to C++17. As suggested in
D131855 disable the code prior to C++17. This removes libc++'s
extension.

Reviewed By: ldionne, #libc_vendors, #libc, philnik

Differential Revision: https://reviews.llvm.org/D133216

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[libc++] Implements 128-bit support in to_chars.

This is required by the Standard and makes it possible to add full
128-bit support to format.

The patch also fixes 128-bit from_chars "support". One

[libc++] Implements 128-bit support in to_chars.

This is required by the Standard and makes it possible to add full
128-bit support to format.

The patch also fixes 128-bit from_chars "support". One unit test
required a too large value, this failed on 128-bit; the fix was to add
more characters to the input.

Note only base 10 has been optimized. Other bases can be optimized.

Note the 128-bit lookup table could be made smaller. This will be done later. I
really want to get 128-bit working in to_chars and format in the upcomming
LLVM 15 release, these optimizations aren't critical.

Reviewed By: #libc, ldionne

Differential Revision: https://reviews.llvm.org/D128929

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[libc++] Improve charconv base10 algorithm.

This change is a preparation to add the 128-bit integral output.

Before
```
--------------------------------------------------------------
Benchmark

[libc++] Improve charconv base10 algorithm.

This change is a preparation to add the 128-bit integral output.

Before
```
--------------------------------------------------------------
Benchmark Time CPU Iterations
--------------------------------------------------------------
BM_to_chars_good/2 20.1 ns 20.1 ns 35045000
BM_to_chars_good/3 117 ns 117 ns 5916000
BM_to_chars_good/4 83.7 ns 83.7 ns 8401000
BM_to_chars_good/5 70.6 ns 70.6 ns 9915000
BM_to_chars_good/6 59.9 ns 59.9 ns 11678000
BM_to_chars_good/7 53.9 ns 53.8 ns 12995000
BM_to_chars_good/8 19.0 ns 19.0 ns 37110000
BM_to_chars_good/9 45.9 ns 45.8 ns 15278000
BM_to_chars_good/10 9.24 ns 9.24 ns 75343000
BM_to_chars_good/11 42.6 ns 42.6 ns 16449000
BM_to_chars_good/12 38.8 ns 38.8 ns 18101000
BM_to_chars_good/13 38.8 ns 38.8 ns 17999000
BM_to_chars_good/14 37.7 ns 37.6 ns 18571000
BM_to_chars_good/15 35.8 ns 35.8 ns 19660000
BM_to_chars_good/16 15.4 ns 15.4 ns 46129000
BM_to_chars_good/17 32.3 ns 32.3 ns 21763000
BM_to_chars_good/18 32.8 ns 32.8 ns 21396000
BM_to_chars_good/19 33.4 ns 33.4 ns 21078000
BM_to_chars_good/20 33.3 ns 33.3 ns 21020000
BM_to_chars_good/21 32.3 ns 32.3 ns 21807000
BM_to_chars_good/22 31.6 ns 31.6 ns 22057000
BM_to_chars_good/23 30.7 ns 30.7 ns 22938000
BM_to_chars_good/24 28.3 ns 28.3 ns 24659000
BM_to_chars_good/25 28.2 ns 28.2 ns 24790000
BM_to_chars_good/26 28.4 ns 28.4 ns 24410000
BM_to_chars_good/27 28.7 ns 28.7 ns 24423000
BM_to_chars_good/28 28.9 ns 28.9 ns 24139000
BM_to_chars_good/29 28.9 ns 28.9 ns 24347000
BM_to_chars_good/30 29.2 ns 29.2 ns 24141000
BM_to_chars_good/31 29.6 ns 29.6 ns 23699000
BM_to_chars_good/32 29.5 ns 29.5 ns 23933000
BM_to_chars_good/33 28.9 ns 28.9 ns 24042000
BM_to_chars_good/34 28.7 ns 28.7 ns 24361000
BM_to_chars_good/35 28.3 ns 28.3 ns 24703000
BM_to_chars_good/36 28.1 ns 28.1 ns 24924000
BM_to_chars_bad/2 6.16 ns 6.15 ns 114101000
BM_to_chars_bad/3 14.5 ns 14.5 ns 48244000
BM_to_chars_bad/4 16.9 ns 16.9 ns 41974000
BM_to_chars_bad/5 12.5 ns 12.5 ns 56080000
BM_to_chars_bad/6 10.9 ns 10.9 ns 64036000
BM_to_chars_bad/7 14.5 ns 14.5 ns 47294000
BM_to_chars_bad/8 6.36 ns 6.35 ns 110430000
BM_to_chars_bad/9 12.4 ns 12.4 ns 56448000
BM_to_chars_bad/10 5.13 ns 5.13 ns 137596000
BM_to_chars_bad/11 9.88 ns 9.88 ns 69015000
BM_to_chars_bad/12 10.8 ns 10.8 ns 63990000
BM_to_chars_bad/13 10.7 ns 10.7 ns 65066000
BM_to_chars_bad/14 9.71 ns 9.71 ns 71775000
BM_to_chars_bad/15 9.18 ns 9.18 ns 75267000
BM_to_chars_bad/16 6.12 ns 6.12 ns 115000000
BM_to_chars_bad/17 10.7 ns 10.7 ns 65504000
BM_to_chars_bad/18 10.6 ns 10.6 ns 65685000
BM_to_chars_bad/19 9.98 ns 9.98 ns 69894000
BM_to_chars_bad/20 9.74 ns 9.74 ns 72098000
BM_to_chars_bad/21 9.25 ns 9.25 ns 75184000
BM_to_chars_bad/22 9.10 ns 9.10 ns 75602000
BM_to_chars_bad/23 9.48 ns 9.48 ns 72824000
BM_to_chars_bad/24 9.27 ns 9.27 ns 75112000
BM_to_chars_bad/25 9.61 ns 9.61 ns 72080000
BM_to_chars_bad/26 9.72 ns 9.72 ns 72178000
BM_to_chars_bad/27 10.0 ns 10.0 ns 69733000
BM_to_chars_bad/28 10.3 ns 10.3 ns 67409000
BM_to_chars_bad/29 9.97 ns 9.97 ns 69193000
BM_to_chars_bad/30 10.1 ns 10.1 ns 69007000
BM_to_chars_bad/31 9.68 ns 9.68 ns 72232000
BM_to_chars_bad/32 8.99 ns 8.99 ns 76825000
BM_to_chars_bad/33 8.82 ns 8.82 ns 79293000
BM_to_chars_bad/34 8.64 ns 8.64 ns 80441000
BM_to_chars_bad/35 8.96 ns 8.96 ns 75320000
BM_to_chars_bad/36 8.87 ns 8.87 ns 77293000

```

After
```
--------------------------------------------------------------
Benchmark Time CPU Iterations
--------------------------------------------------------------
BM_to_chars_good/2 14.7 ns 14.7 ns 47583000
BM_to_chars_good/3 101 ns 101 ns 6901000
BM_to_chars_good/4 68.4 ns 68.4 ns 10088000
BM_to_chars_good/5 58.2 ns 58.2 ns 12007000
BM_to_chars_good/6 51.1 ns 51.1 ns 13687000
BM_to_chars_good/7 45.6 ns 45.6 ns 15323000
BM_to_chars_good/8 14.6 ns 14.6 ns 47795000
BM_to_chars_good/9 40.7 ns 40.7 ns 17371000
BM_to_chars_good/10 7.48 ns 7.48 ns 90931000
BM_to_chars_good/11 37.6 ns 37.6 ns 18542000
BM_to_chars_good/12 35.2 ns 35.2 ns 19922000
BM_to_chars_good/13 34.9 ns 34.9 ns 20105000
BM_to_chars_good/14 33.5 ns 33.5 ns 20863000
BM_to_chars_good/15 31.9 ns 31.9 ns 22014000
BM_to_chars_good/16 11.7 ns 11.7 ns 60012000
BM_to_chars_good/17 28.9 ns 28.9 ns 24148000
BM_to_chars_good/18 29.0 ns 29.0 ns 24317000
BM_to_chars_good/19 28.7 ns 28.7 ns 24363000
BM_to_chars_good/20 28.1 ns 28.1 ns 24899000
BM_to_chars_good/21 27.5 ns 27.5 ns 25499000
BM_to_chars_good/22 26.9 ns 26.9 ns 25929000
BM_to_chars_good/23 26.2 ns 26.2 ns 26828000
BM_to_chars_good/24 25.1 ns 25.1 ns 27742000
BM_to_chars_good/25 25.3 ns 25.3 ns 27720000
BM_to_chars_good/26 25.2 ns 25.2 ns 27789000
BM_to_chars_good/27 25.3 ns 25.3 ns 27777000
BM_to_chars_good/28 25.3 ns 25.3 ns 27643000
BM_to_chars_good/29 25.3 ns 25.3 ns 27750000
BM_to_chars_good/30 25.4 ns 25.4 ns 27566000
BM_to_chars_good/31 25.4 ns 25.4 ns 27611000
BM_to_chars_good/32 25.8 ns 25.8 ns 27218000
BM_to_chars_good/33 25.7 ns 25.7 ns 27070000
BM_to_chars_good/34 26.1 ns 26.1 ns 26693000
BM_to_chars_good/35 26.4 ns 26.4 ns 26486000
BM_to_chars_good/36 26.3 ns 26.3 ns 26619000
BM_to_chars_bad/2 5.99 ns 5.99 ns 118787000
BM_to_chars_bad/3 14.3 ns 14.3 ns 48567000
BM_to_chars_bad/4 16.0 ns 16.0 ns 43239000
BM_to_chars_bad/5 12.6 ns 12.6 ns 55354000
BM_to_chars_bad/6 10.7 ns 10.7 ns 65491000
BM_to_chars_bad/7 14.4 ns 14.4 ns 48723000
BM_to_chars_bad/8 6.50 ns 6.50 ns 104967000
BM_to_chars_bad/9 12.0 ns 12.0 ns 56552000
BM_to_chars_bad/10 5.16 ns 5.16 ns 136380000
BM_to_chars_bad/11 10.5 ns 10.5 ns 66764000
BM_to_chars_bad/12 10.7 ns 10.7 ns 65534000
BM_to_chars_bad/13 11.0 ns 11.0 ns 63426000
BM_to_chars_bad/14 9.90 ns 9.90 ns 68575000
BM_to_chars_bad/15 9.52 ns 9.52 ns 70932000
BM_to_chars_bad/16 6.14 ns 6.14 ns 111762000
BM_to_chars_bad/17 10.6 ns 10.6 ns 65883000
BM_to_chars_bad/18 10.5 ns 10.5 ns 67606000
BM_to_chars_bad/19 9.96 ns 9.96 ns 68898000
BM_to_chars_bad/20 9.40 ns 9.41 ns 73116000
BM_to_chars_bad/21 9.12 ns 9.12 ns 78647000
BM_to_chars_bad/22 8.95 ns 8.95 ns 80211000
BM_to_chars_bad/23 9.50 ns 9.49 ns 73571000
BM_to_chars_bad/24 9.29 ns 9.29 ns 74690000
BM_to_chars_bad/25 9.65 ns 9.65 ns 72877000
BM_to_chars_bad/26 9.78 ns 9.78 ns 70171000
BM_to_chars_bad/27 10.1 ns 10.1 ns 69543000
BM_to_chars_bad/28 10.4 ns 10.4 ns 67582000
BM_to_chars_bad/29 10.00 ns 10.00 ns 70806000
BM_to_chars_bad/30 9.99 ns 9.99 ns 70340000
BM_to_chars_bad/31 9.56 ns 9.56 ns 74159000
BM_to_chars_bad/32 8.97 ns 8.97 ns 78052000
BM_to_chars_bad/33 8.86 ns 8.86 ns 78586000
BM_to_chars_bad/34 8.81 ns 8.81 ns 78562000
BM_to_chars_bad/35 8.90 ns 8.90 ns 77384000
BM_to_chars_bad/36 9.04 ns 9.04 ns 77263000

```

Reviewed By: #libc, ldionne

Differential Revision: https://reviews.llvm.org/D127764

show more ...

[libc++] Don't use static constexpr in headers.

This was noticed in the review of D125704. In that commit only the new
table has been adapted. This adapts the existing tables.

Note since libc++'s c

[libc++] Don't use static constexpr in headers.

This was noticed in the review of D125704. In that commit only the new
table has been adapted. This adapts the existing tables.

Note since libc++'s charconv is backported to C++11 it's not possible to
use inline constexpr variables. The were introduced in C++17.

Reviewed By: #libc, ldionne

Differential Revision: https://reviews.llvm.org/D126887

show more ...

[libc++] Make to_chars base 10 header only.

The functions to_chars and from_chars should offer 128-bit support. This
is the first step to implement 128-bit version of to_chars. Before
implementing 1

[libc++] Make to_chars base 10 header only.

The functions to_chars and from_chars should offer 128-bit support. This
is the first step to implement 128-bit version of to_chars. Before
implementing 128-bit support the current code will be polished.

This moves the code from the dylib to the header in prepartion of

P2291 "Add Constexpr Modifiers to Functions to_chars and from_chars for
Integral Types in <charconv> Header"

Note some more cleanups will be done in follow-up commits
- Remove the _LIBCPP_AVAILABILITY_TO_CHARS from to_chars. With all code
in the header the availablilty macro is no longer needed. This
requires enabling the unit tests for additional platforms.
- The code in the dylib can switch to using the header implementation.
This allows removing the code duplicated in the header and the dylib.

Reviewed By: #libc, ldionne

Differential Revision: https://reviews.llvm.org/D125704

show more ...