106 Commits

Author SHA1 Message Date
Louis Dionne
87d56c59f5
[libc++][modules] Guard carved-out headers more consistently (#108637)
Several headers that should not be provided when localization or threads
are disabled were not guarded. That works until one tries to build with
modules and these headers get pulled in.

Note that this could be cleaned up further into something more
systematic, but this patch solves the immediate problems I ran into with
the monolithic modulemap and doesn't create any new inconsistency that
wasn't already there.
2024-09-16 08:15:38 -04:00
Louis Dionne
1f0d545ec3
[libc++] Fix wraparound issue with -fsanitize=integer in string operator>> (#106263)
Fixes #106261
rdar://133991190
2024-08-29 16:37:25 -04:00
Nikolas Klauser
bbe4a80605
[libc++] Enable modernize-use-equals-delete (#93293)
Differential Revision: https://reviews.llvm.org/D121213
2024-06-18 10:51:57 +02:00
Nikolas Klauser
17f006207c
[libc++] Granularize <ostream> (#85537)
This also includes `<__ostream/basic_ostream.h>` in `<sstream>` now,
reducing the include time of `<complex>` from 819ms to 603ms.
2024-05-02 22:38:44 +02:00
Louis Dionne
37dca605c9
[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
2024-02-29 10:12:22 -05:00
Mark de Wever
54daf6af57
[libc++] Fixes istream::sync. (#76467)
This fixes two issues.

The return value
----------------

Based on the wording

[istream.unformatted]/37
Effects: Behaves as an unformatted input function (as described above),
  except that it does not count the number of characters extracted and
  does not affect the value returned by subsequent calls to gcount().
  After constructing a sentry object, if rdbuf() is a null pointer,
  returns -1.

[istream.unformatted]/1
... It then creates an object of class sentry with the default argument
noskipws (second) argument true. If the sentry object returns true, when
converted to a value of type bool, the function endeavors to obtain the
  requested input. ...

It could be argued the current behaviour is correct, however
constructing a istream rdbuf() == nullptr creates a sentry that returns
false; its state is always bad in this case.

As mentioned in the bug report, after this change the 3 major
implementations behave the same.

The setting of the state
------------------------

When pubsync returned -1 it updated the local __state variable and
returned. This early return caused the state up the istream not to be
updated to the new state.

Fixes: https://github.com/llvm/llvm-project/issues/51497
Fixes: https://github.com/llvm/llvm-project/issues/51499

---------

Co-authored-by: Louis Dionne <ldionne.2@gmail.com>
2024-02-18 17:20:49 +01:00
Nikolas Klauser
f9d6d6fbcc
[libc++] Move the contents of __fwd/get.h into the forward declaration headers they actually belong to (#81368)
This brings us closer to one forward declaring header per public header.
2024-02-12 08:32:28 +01:00
Louis Dionne
9783f28cbb
[libc++] Format the code base (#74334)
This patch runs clang-format on all of libcxx/include and libcxx/src, in
accordance with the RFC discussed at [1]. Follow-up patches will format
the benchmarks, the test suite and remaining parts of the code. I'm
splitting this one into its own patch so the diff is a bit easier to
review.

This patch was generated with:

   find libcxx/include libcxx/src -type f \
      | grep -v 'module.modulemap.in' \
      | grep -v 'CMakeLists.txt' \
      | grep -v 'README.txt' \
      | grep -v 'libcxx.imp' \
      | grep -v '__config_site.in' \
      | xargs clang-format -i

A Git merge driver is available in libcxx/utils/clang-format-merge-driver.sh
to help resolve merge and rebase issues across these formatting changes.

[1]: https://discourse.llvm.org/t/rfc-clang-formatting-all-of-libc-once-and-for-all
2023-12-18 14:01:33 -05:00
Louis Dionne
77a00c0d54
[libc++] Replace uses of _VSTD:: by std:: (#74331)
As part of the upcoming clang-formatting of libc++, this patch performs
the long desired removal of the _VSTD macro.

See https://discourse.llvm.org/t/rfc-clang-formatting-all-of-libc-once-and-for-all
for the clang-format proposal.
2023-12-05 11:19:15 -05:00
Louis Dionne
4c19854222
[libc++] Rename _LIBCPP_INLINE_VISIBILITY to _LIBCPP_HIDE_FROM_ABI (#74095)
In preparation for running clang-format on the whole code base, we are
also removing mentions of the legacy _LIBCPP_INLINE_VISIBILITY macro in
favor of the newer _LIBCPP_HIDE_FROM_ABI.

We're still leaving the definition of _LIBCPP_INLINE_VISIBILITY to avoid
creating needless breakage in case some older patches are checked-in
with mentions of the old macro. After we branch for LLVM 18, we can do
another pass to clean up remaining uses of the macro that might have
gotten introduced by mistake (if any) and remove the macro itself at the
same time. This is just a minor convenience to smooth out the transition
as much as possible.

See
https://discourse.llvm.org/t/rfc-clang-formatting-all-of-libc-once-and-for-all
for the clang-format proposal.
2023-12-04 10:25:14 -05:00
philnik777
a65070a76a
[libc++] Remove a few transitive includes (#70553) 2023-10-29 18:31:37 +01:00
Nikolas Klauser
6256ccfd4f [libc++][NFC] Update the remaining enable_ifs
This brings most of the enable_ifs in libc++ to the same style.

Reviewed By: #libc, ldionne

Spies: ldionne, libcxx-commits

Differential Revision: https://reviews.llvm.org/D157753
2023-09-01 17:51:17 -07:00
yronglin
06ef752b7c [libc++] Implement LWG3464(istream::gcount() can overflow)
Implement LWG3464 https://wg21.link/LWG3464

Reviewed By: #libc, Mordante, philnik

Differential Revision: https://reviews.llvm.org/D158749
2023-08-29 20:18:25 +08:00
yronglin
2051a41219 Revert "[libc++] Implement LWG3464(istream::gcount() can overflow)"
This reverts commit d57fe1dbe0506c006d8f082101a7c00fde798ddb.
2023-08-27 13:34:32 +08:00
yronglin
d57fe1dbe0 [libc++] Implement LWG3464(istream::gcount() can overflow)
Implement LWG3464 https://wg21.link/LWG3464

Reviewed By: Mordante

Differential Revision: https://reviews.llvm.org/D158749
2023-08-27 11:24:40 +08:00
Nikolas Klauser
140c375ab1 Revert "[libc++] Apply _LIBCPP_EXCLUDE_FROM_EXPLICIT_INSTANTIATION only in classes that we have instantiated externally"
This reverts commit b3c9150062dc4264afb4a3d2790f071c1ebe0743.

There were unexpected breakages downstream. @EricWF is investigating.
2023-05-24 08:48:18 -07:00
Nikolas Klauser
b3c9150062 [libc++] Apply _LIBCPP_EXCLUDE_FROM_EXPLICIT_INSTANTIATION only in classes that we have instantiated externally
To make sure all member functions that require it are marked `_LIBCPP_EXCLUDE_FROM_EXPLICIT_INSTANTIATION` I compared the output of `objdump --syms lib/libc++.1.0.dylib` before and after, ignoring addresses.

Reviewed By: #libc, ldionne

Spies: Mordante, libcxx-commits, ldionne, arichardson, mstorsjo

Differential Revision: https://reviews.llvm.org/D150896
2023-05-23 13:32:55 -07:00
Mark de Wever
9d16cbc5c8 [libc++] Adds more forward declaration headers.
The module validation script of D144994 validate whether the contents of
an include match its module. An include is the set of files matching the
pattern:
- foo
- foo/*.
- __fwd/foo.h

Several declarations of the stream headers are in the header iosfwd.
This gives issue using the validation script. Adding iosfwd to the set
of matching files gives too many declarations. For example when
validating the fstream header it will pull in declarations of the
istream header. Instead if writing a set of filters the headers are
granularized into smaller headers containing the expected declarations.

Reviewed By: #libc, ldionne

Differential Revision: https://reviews.llvm.org/D148927
2023-04-27 17:07:10 +02:00
Nikolas Klauser
43562287a8 [libc++] Granularize <exception>
This patch also updates the moved code to the new style (i.e. formatted, replaced marcos and typedefs)

Reviewed By: ldionne, #libc

Spies: arichardson, libcxx-commits

Differential Revision: https://reviews.llvm.org/D145095
2023-03-12 22:19:41 +01:00
Nikolas Klauser
0a4aa8a122 [libc++] Granularize <type_traits> includes
Reviewed By: ldionne, #libc, #libc_abi

Spies: #libc_vendors, smeenai, libcxx-commits

Differential Revision: https://reviews.llvm.org/D145320
2023-03-08 22:05:04 +01:00
Nikolas Klauser
b22aa3d74f [libc++][NFC] Rename _LIBCPP_NO_EXCEPTIONS to _LIBCPP_HAS_NO_EXCEPTIONS
Other macros that disable parts of the library are named `_LIBCPP_HAS_NO_WHATEVER`.

Reviewed By: ldionne, Mordante, #libc

Spies: libcxx-commits, smeenai

Differential Revision: https://reviews.llvm.org/D143163
2023-02-17 17:39:03 +01:00
Nikolas Klauser
4f15267d3d [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
2023-02-15 16:52:25 +01:00
Nikolas Klauser
73e8e1ba8d [libc++][NFC] Qualify declval
While it's not necessary to qualify calls to `declval` it makes error messages very crypric if the declaration isn't reachable anymore

For example:
```
    /home/nikolask/llvm-projects/libcxx/build/include/c++/v1/__chrono/duration.h:53:66: error: no type named 'type' in 'std::common_type<long, long>'
        typedef chrono::duration<typename common_type<_Rep1, _Rep2>::type,
                                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~
    /home/nikolask/llvm-projects/libcxx/build/include/c++/v1/__type_traits/common_type.h:107:14: note: in instantiation of template class 'std::common_type<std::chrono::duration<long, std::ratio<3600, 1>>, std::chrono::duration<long, std::ratio<3600, 1>>>' requested here
        : public common_type<_Tp, _Tp> {};
                 ^
    /home/nikolask/llvm-projects/libcxx/build/include/c++/v1/__chrono/duration.h:279:58: note: in instantiation of template class 'std::common_type<std::chrono::duration<long, std::ratio<3600, 1>>>' requested here
        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR typename common_type<duration>::type operator+() const {return typename common_type<duration>::type(*this);}
                                                             ^
    /home/nikolask/llvm-projects/libcxx/build/include/c++/v1/__chrono/duration.h:308:54: note: in instantiation of template class 'std::chrono::duration<long, std::ratio<3600, 1>>' requested here
    typedef duration<     int, ratio_multiply<ratio<24>, hours::period>>         days;
                                                         ^
    /home/nikolask/llvm-projects/libcxx/build/include/c++/v1/__chrono/duration.h:280:81: error: no type named 'type' in 'std::common_type<std::chrono::duration<long, std::ratio<3600, 1>>>'
        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR typename common_type<duration>::type operator-() const {return typename common_type<duration>::type(-__rep_);}
                                                    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~
    /home/nikolask/llvm-projects/libcxx/build/include/c++/v1/__chrono/duration.h:308:54: note: in instantiation of template class 'std::chrono::duration<long, std::ratio<3600, 1>>' requested here
    typedef duration<     int, ratio_multiply<ratio<24>, hours::period>>         days;
                                                         ^
    /home/nikolask/llvm-projects/libcxx/build/include/c++/v1/__chrono/duration.h:53:66: error: no type named 'type' in 'std::common_type<int, int>'
        typedef chrono::duration<typename common_type<_Rep1, _Rep2>::type,
                                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~
    /home/nikolask/llvm-projects/libcxx/build/include/c++/v1/__type_traits/common_type.h:107:14: note: in instantiation of template class 'std::common_type<std::chrono::duration<int, std::ratio<86400, 1>>, std::chrono::duration<int, std::ratio<86400, 1>>>' requested here
        : public common_type<_Tp, _Tp> {};
                 ^
    /home/nikolask/llvm-projects/libcxx/build/include/c++/v1/__chrono/duration.h:279:58: note: in instantiation of template class 'std::common_type<std::chrono::duration<int, std::ratio<86400, 1>>>' requested here
        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR typename common_type<duration>::type operator+() const {return typename common_type<duration>::type(*this);}
                                                             ^
    /home/nikolask/llvm-projects/libcxx/build/include/c++/v1/__chrono/duration.h:309:55: note: in instantiation of template class 'std::chrono::duration<int, std::ratio<86400, 1>>' requested here
    typedef duration<     int, ratio_multiply<ratio<7>,   days::period>>         weeks;
                                                          ^
    19 similar errors omitted
```
changes with qualification added to:
```
    While building module 'std' imported from /home/nikolask/llvm-projects/libcxx/libcxx/test/std/utilities/meta/meta.trans/meta.trans.other/common_type.pass.cpp:13:
    In file included from <module-includes>:17:
    In file included from /home/nikolask/llvm-projects/libcxx/build/include/c++/v1/math.h:309:
    In file included from /home/nikolask/llvm-projects/libcxx/build/include/c++/v1/limits:107:
    In file included from /home/nikolask/llvm-projects/libcxx/build/include/c++/v1/type_traits:432:
    In file included from /home/nikolask/llvm-projects/libcxx/build/include/c++/v1/__type_traits/common_reference.h:13:
    /home/nikolask/llvm-projects/libcxx/build/include/c++/v1/__type_traits/common_type.h:28:43: error: declaration of 'declval' must be imported from module 'std.utility.__utility.declval' before it is required
    using __cond_type = decltype(false ? std::declval<_Tp>() : std::declval<_Up>());
                                              ^
    /home/nikolask/llvm-projects/libcxx/build/include/c++/v1/__utility/declval.h:30:34: note: declaration here is not visible
    decltype(std::__declval<_Tp>(0)) declval() _NOEXCEPT;
                                     ^
    /home/nikolask/llvm-projects/libcxx/libcxx/test/std/utilities/meta/meta.trans/meta.trans.other/common_type.pass.cpp:13:10: fatal error: could not build module 'std'
    #include <functional>
     ~~~~~~~~^
    2 errors generated.
```

Reviewed By: ldionne, Mordante, #libc

Spies: libcxx-commits

Differential Revision: https://reviews.llvm.org/D130854
2023-01-12 18:28:41 +01:00
Nikolas Klauser
841399a218 [libc++] Add custom clang-tidy checks
Reviewed By: #libc, ldionne

Spies: jwakely, beanz, smeenai, cfe-commits, tschuett, avogelsgesang, Mordante, sstefan1, libcxx-commits, ldionne, mgorny, arichardson, miyuki

Differential Revision: https://reviews.llvm.org/D131963
2022-12-23 15:42:13 +01:00
Nikolas Klauser
e0a66116fc [libc++] Granularize <type_traits> includes in <compare>
Reviewed By: Mordante, #libc

Spies: libcxx-commits

Differential Revision: https://reviews.llvm.org/D140480
2022-12-23 02:58:06 +01:00
Nikolas Klauser
89b356f05a [libc++] Granularize <concept> includes
Reviewed By: ldionne, #libc

Spies: libcxx-commits

Differential Revision: https://reviews.llvm.org/D137283
2022-11-05 20:59:29 +01:00
Nikolas Klauser
4262b523ff [libc++][NFC] Enable modernize-use-override
Reviewed By: Mordante, #libc

Spies: aheejin, libcxx-commits, smeenai

Differential Revision: https://reviews.llvm.org/D124714
2022-08-25 20:55:08 +02:00
Nikolas Klauser
80c7e93a2a [libc++] Add a bunch of missing _LIBCPP_HIDE_FROM_ABI
Reviewed By: ldionne, Mordante, var-const, huixie90, #libc

Spies: jloser, libcxx-commits, arichardson, miyuki

Differential Revision: https://reviews.llvm.org/D129968
2022-08-13 22:41:22 +02:00
Nikolas Klauser
3cd4531b9b [libc++] Granularize <iterator> includes
Reviewed By: ldionne, #libc

Spies: libcxx-commits, wenlei

Differential Revision: https://reviews.llvm.org/D127445
2022-06-10 22:43:57 +02:00
Louis Dionne
2ae52326da [libc++] Towards a simpler extern template story in libc++
The flexibility around extern template instantiation declarations in
libc++ result in a very complicated model, especially when support for
slightly different configurations (like the debug mode or assertions
in the dylib) are taken into account. That results in unexpected bugs
like http://llvm.org/PR50534 (and there have been multiple similar
bugs in the past, notably around the debug mode).

This patch gets rid of the _LIBCPP_DISABLE_EXTERN_TEMPLATE knob, which
I don't think is fundamental. Indeed, the motivation for that knob was to
avoid taking a dependency on the library, however that can be done better
by linking against the static library instead. And in fact, some parts of
the headers will always depend on things defined in the library, which
defeats the original goal of _LIBCPP_DISABLE_EXTERN_TEMPLATE.

Differential Revision: https://reviews.llvm.org/D103960
2022-06-08 22:05:07 -04:00
Louis Dionne
385cc25a53 [libc++] Ensure that all public C++ headers include <__assert>
This patch changes the requirement for getting the declaration of the
assertion handler from including <__assert> to including any public
C++ header of the library. Note that C compatibility headers are
excluded because we don't implement all the C headers ourselves --
some of them are taken straight from the C library, like assert.h.

It also adds a generated test to check it. Furthermore, this new
generated test is designed in a way that will make it possible to
replace almost all the existing test-generation scripts with this
system in upcoming patches.

Differential Revision: https://reviews.llvm.org/D122506
2022-03-30 15:05:31 -04:00
Louis Dionne
e39095a32e [libc++] Define _LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER whenever we enable warnings in the test suite
This should make CI consistent on all the compilers we support. Most of
this patch is working around various warnings emitted by GCC in our code
base, which are now being shown when we compile the tests.

After this patch, the whole test suite should be warning free on all
compilers we support and test, except for a few warnings on GCC that
we silence explicitly until we figure out the proper fix for them.

Differential Revision: https://reviews.llvm.org/D120684
2022-03-15 17:17:54 -04:00
Arthur O'Dwyer
fa6b9e4010 [libc++] Normalize all our '#pragma GCC system_header', and regression-test.
Now we'll notice if a header forgets to include this magic phrase.

Differential Revision: https://reviews.llvm.org/D118800
2022-02-04 12:27:19 -05:00
Nikolas Klauser
feb80aa96b [libc++] = delete member functions with // = delete;
Use `= delete` for member functions that are marked with `// = delete;`

Reviewed By: ldionne, Quuxplusone, #libc

Spies: jloser, libcxx-commits

Differential Revision: https://reviews.llvm.org/D115291
2021-12-08 19:29:44 +01:00
Louis Dionne
eb8650a757 [runtimes][NFC] Remove filenames at the top of the license notice
We've stopped doing it in libc++ for a while now because these names
would end up rotting as we move things around and copy/paste stuff.
This cleans up all the existing files so as to stop the spreading
as people copy-paste headers around.
2021-11-17 16:30:52 -05:00
Louis Dionne
f4c1258d56 [libc++] Add an option to disable wide character support in libc++
Some embedded platforms do not wish to support the C library functionality
for handling wchar_t because they have no use for it. It makes sense for
libc++ to work properly on those platforms, so this commit adds a carve-out
of functionality for wchar_t.

Unfortunately, unlike some other carve-outs (e.g. random device), this
patch touches several parts of the library. However, despite the wide
impact of this patch, I still think it is important to support this
configuration since it makes it much simpler to port libc++ to some
embedded platforms.

Differential Revision: https://reviews.llvm.org/D111265
2021-10-12 06:08:23 -04:00
Arthur O'Dwyer
a8d1182f66 [libc++] Remove some _LIBCPP_CXX03_LANG from iostreams headers.
With the STL containers, I didn't enable move operations in C++03 mode
because that would change the overload resolution for things that today
are copy operations. With iostreams, though, the copy operations aren't
present at all, and so I see no problem with enabling move operations
even in (Clang's greatly extended) C++03 mode.

Clang's C++03 mode does not support delegating constructors.

Differential Revision: https://reviews.llvm.org/D104310
2021-06-28 12:55:26 -04:00
Arthur O'Dwyer
585496803c [libc++] Enable the rvalue overloads of operator<< and operator>> even in C++03.
Continuing to eliminate no-longer-needed uses of _LIBCPP_CXX03_LANG.

Differential Revision: https://reviews.llvm.org/D104725
2021-06-25 14:59:58 -04:00
Christopher Di Bella
6adbc83ee9 [libcxx][modularisation] moves <utility> content out of <type_traits>
Moves:

* `std::move`, `std::forward`, `std::declval`, and `std::swap` into
  `__utility/${FUNCTION_NAME}`.
* `std::swap_ranges` and `std::iter_swap` into
  `__algorithm/${FUNCTION_NAME}`

Differential Revision: https://reviews.llvm.org/D103734
2021-06-24 17:57:29 +00:00
Arthur O'Dwyer
317e92a3e8 [libc++] Enable explicit conversion operators, even in C++03 mode.
C++03 didn't support `explicit` conversion operators;
but Clang's C++03 mode does, as an extension, so we can use it.
This lets us make the conversion explicit in `std::function` (even in '03),
and remove some silly metaprogramming in `std::basic_ios`.

Drive-by improvements to the tests for these operators, in addition
to making sure all these tests also run in `c++03` mode.

Differential Revision: https://reviews.llvm.org/D104682
2021-06-22 13:35:59 -04:00
Arthur O'Dwyer
bfbd73f87d [libc++] Alphabetize and include-what-you-use. NFCI.
Differential Revision: https://reviews.llvm.org/D102781
2021-05-29 19:54:48 -04:00
Arthur O'Dwyer
ab3fcc5065 [libc++] s/_VSTD::declval/declval/g. NFCI. 2021-05-11 12:23:55 -04:00
Louis Dionne
4cd6ca102a [libc++] NFC: Normalize #endif // comment indentation 2021-04-20 12:03:32 -04:00
Bruce Mitchener
527a7fdfbd [libc++] Replace several uses of 0 by nullptr
Differential Revision: https://reviews.llvm.org/D43159
2020-11-27 10:00:21 -05:00
Louis Dionne
ce565861c7 [libc++] Drop old workaround for iostreams instantiations missing from the dylib
On old Apple platforms (pre 10.9), we couldn't rely on the iostreams
explicit instantiations being part of the dylib. However, we don't
support back-deploying to such old deployment targets anymore, so the
workaround can be dropped.
2020-10-22 14:51:25 -04:00
Louis Dionne
c90dee1e90 [libc++] Re-apply fdc41e11f (LWG1203) without breaking the C++11 build
fdc41e11f was reverted in e46c1def5 because it broke the C++11 build.
We shouldn't be using enable_if_t in C++11, instead we must use
enable_if<...>::type.
2020-09-23 08:56:00 -04:00
Raphael Isemann
e46c1def52 Revert "[libc++] Implement LWG1203"
This reverts commit fdc41e11f9687a50c97e2a59663bf2d541ff5489. It causes the
libcxx/modules/stds_include.sh.cpp test to fail with:
libcxx/include/ostream:1039:45: error: no template named 'enable_if_t'; did you mean 'enable_if'?
template <class _Stream, class _Tp, class = enable_if_t<

Still investigating what's causing this and reverting in the meantime to get
the bots green again.
2020-09-23 10:13:38 +02:00
Louis Dionne
fdc41e11f9 [libc++] Implement LWG1203
Libc++ had an issue where nonsensical code like

  decltype(std::stringstream{} << std::vector<int>{});

would compile, as long as you kept the expression inside decltype in
an unevaluated operand. This turned out to be that we didn't implement
LWG1203, which clarifies what we should do in that case.

rdar://58769296
2020-09-22 17:15:31 -04:00
Louis Dionne
fc4486c247 [libc++] Implement LWG 3199
Summary:
The resolution of LWG 3199 makes sure that input-streaming into an empty bitset
does not set the failbit on the input stream.

Reviewers: mclow.lists, EricWF

Subscribers: christof, jkorous, dexonsmith, libcxx-commits

Tags: #libc

Differential Revision: https://reviews.llvm.org/D65105

llvm-svn: 369422
2019-08-20 18:21:06 +00:00
Louis Dionne
396145d0da [libc++] Fix error flags and exceptions propagated from input stream operations
Summary:
This is a re-application of r357533 and r357531. They had been reverted
because we thought the commits broke the LLDB data formatters, but it
turns out this was because only r357531 had been included in the CI
run.

Before this patch, we would only ever throw an exception if the badbit
was set on the stream. The Standard is currently very unclear on how
exceptions should be propagated and what error flags should be set by
the input stream operations. This commit changes libc++ to behave under
a different (but valid) interpretation of the Standard. This interpretation
of the Standard matches what other implementations are doing.

This effectively implements the wording in p1264r0. It hasn't been voted
into the Standard yet, however there is wide agreement that the fix is
correct and it's just a matter of time before the fix is standardized.

PR21586
PR15949
rdar://problem/15347558

Reviewers: mclow.lists, EricWF

Subscribers: christof, dexonsmith, cfe-commits

Differential Revision: https://reviews.llvm.org/D49863

llvm-svn: 357775
2019-04-05 16:33:37 +00:00