Commit Graph

226 Commits

Author SHA1 Message Date
Martin Storsjö 529a79302b Reapply #2 of [runtimes] Fix building initial libunwind+libcxxabi+libcxx with compiler implied -lunwind
This does mostly the same as D112126, but for the runtimes cmake files.
Most of that is straightforward, but the interdependency between
libcxx and libunwind is tricky:

Libunwind is built at the same time as libcxx, but libunwind is not
installed yet. LIBCXXABI_USE_LLVM_UNWINDER makes libcxx link directly
against the just-built libunwind, but the compiler implicit -lunwind
isn't found. This patch avoids that by adding --unwindlib=none if
supported, if we are going to link explicitly against a newly built
unwinder anyway.

Since the previous attempt, this no longer uses
llvm_enable_language_nolink (and thus doesn't set
CMAKE_TRY_COMPILE_TARGET_TYPE=STATIC_LIBRARY during the compiler
sanity checks). Setting CMAKE_TRY_COMPILE_TARGET_TYPE=STATIC_LIBRARY
during compiler sanity checks makes cmake not learn about some
aspects of the compiler, which can make further find_library or
find_package fail. This caused OpenMP to not detect libelf and libffi,
disabling some OpenMP target plugins.

Instead, require the caller to set CMAKE_{C,CXX}_COMPILER_WORKS=YES
when building in a configuration with an incomplete toolchain.

Differential Revision: https://reviews.llvm.org/D113253
2021-12-09 21:38:14 +02:00
Martin Storsjö 62cff45d76 Revert "Reapply [runtimes] Fix building initial libunwind+libcxxabi+libcxx with compiler implied -lunwind"
This reverts commit 317dc31e53.

After that change, OpenMP doesn't find dependencies in the host
system (it fails do find e.g. /usr/lib/x86_64-linux-gnu/libelf.so
which it found before), which causes some OpenMP target offloading
plugins to not be found. This doesn't break the build, but just
causes the AMDGPU OpenMP target plugin to be omitted. See
https://reviews.llvm.org/D113253#3181934 for the report of this
issue.
2021-12-09 12:56:57 +02:00
Martin Storsjö 317dc31e53 Reapply [runtimes] Fix building initial libunwind+libcxxabi+libcxx with compiler implied -lunwind
This does mostly the same as D112126, but for the runtimes cmake files.
Most of that is straightforward, but the interdependency between
libcxx and libunwind is tricky:

Libunwind is built at the same time as libcxx, but libunwind is not
installed yet. LIBCXXABI_USE_LLVM_UNWINDER makes libcxx link directly
against the just-built libunwind, but the compiler implicit -lunwind
isn't found. This patch avoids that by adding --unwindlib=none if
supported, if we are going to link explicitly against a newly built
unwinder anyway.

Reapplying this after
db32c4f456, which should fix the issues
that were reported last time this was applied.

Differential Revision: https://reviews.llvm.org/D113253
2021-12-08 00:32:40 +02:00
Louis Dionne fa1c077b41 [runtimes] Remove support for GCC-style 32 bit multilib builds
This patch removes the ability to build the runtimes in the 32 bit
multilib configuration, i.e. using -m32. Instead of doing this, one
should cross-compile the runtimes for the appropriate target triple,
like we do for all other triples.

As it stands, -m32 has several issues, which all seem to be related to
the fact that it's not well supported by the operating systems that
libc++ support. The simplest path towards fixing this is to remove
support for the configuration, which is also the best course of action
if there is little interest for keeping that configuration. If there
is a desire to keep this configuration around, we'll need to do some
work to figure out the underlying issues and fix them.

Differential Revision: https://reviews.llvm.org/D114473
2021-12-01 12:57:01 -05:00
Martin Storsjö efbe9ae23f Revert "[runtimes] Fix building initial libunwind+libcxxabi+libcxx with compiler implied -lunwind"
This reverts commit 7c3d19ab7b.

This commit was reported as causing build problems for the amdgpu
buildbot in https://reviews.llvm.org/D113253#3137097.
2021-11-17 12:50:33 +02:00
Martin Storsjö f5ca3ac748 [libcxx] [ci] Add CI configurations for MinGW
Mention support for MinGW in the docs. Rename the existing windows
CI jobs to Clang-cl, as both Clang-cl and MinGW are equally much
"Windows", just different toolchain environments.

Add an XFAIL for a recently added test that fails in the MinGW DLL
configuration (with an explanation of what's causing the failure).

Differential Revision: https://reviews.llvm.org/D112215
2021-11-17 10:00:50 +02:00
Martin Storsjö 7c3d19ab7b [runtimes] Fix building initial libunwind+libcxxabi+libcxx with compiler implied -lunwind
This does mostly the same as D112126, but for the runtimes cmake files.
Most of that is straightforward, but the interdependency between
libcxx and libunwind is tricky:

Libunwind is built at the same time as libcxx, but libunwind is not
installed yet. LIBCXXABI_USE_LLVM_UNWINDER makes libcxx link directly
against the just-built libunwind, but the compiler implicit -lunwind
isn't found. This patch avoids that by adding --unwindlib=none if
supported, if we are going to link explicitly against a newly built
unwinder anyway.

Differential Revision: https://reviews.llvm.org/D113253
2021-11-16 23:04:06 +02:00
Petr Hosek 22acda48ff [CMake] Cache the compiler-rt library search results
There's a lot of duplicated calls to find various compiler-rt libraries
from build of runtime libraries like libunwind, libc++, libc++abi and
compiler-rt. The compiler-rt helper module already implemented caching
for results avoid repeated Clang invocations.

This change moves the compiler-rt implementation into a shared location
and reuses it from other runtimes to reduce duplication and speed up
the build.

Differential Revision: https://reviews.llvm.org/D88458
2021-10-27 17:53:03 -07:00
Petr Hosek ba4920e98e Revert "[CMake] Cache the compiler-rt library search results"
This reverts commit 0eed292fba, there
are compiler-rt build failures that appear to have been introduced
by this change.
2021-10-21 10:32:01 -07:00
Louis Dionne cbe3b6b21f [libc++] Move LIBCXX-DEBUG-FIXME to params.py
This temporary FIXME really belongs to the testing config, not to the
specific CMake cache that enables that configuration.

Differential Revision: https://reviews.llvm.org/D112031
2021-10-20 09:23:03 -04:00
Petr Hosek 0eed292fba [CMake] Cache the compiler-rt library search results
There's a lot of duplicated calls to find various compiler-rt libraries
from build of runtime libraries like libunwind, libc++, libc++abi and
compiler-rt. The compiler-rt helper module already implemented caching
for results avoid repeated Clang invocations.

This change moves the compiler-rt implementation into a shared location
and reuses it from other runtimes to reduce duplication and speed up
the build.

Differential Revision: https://reviews.llvm.org/D88458
2021-10-18 14:44:07 -07:00
Mikhail Dvorskiy 6069a6a504 [pstl] Initial implementation of OpenMP backend, on behalf of Christopher Nelson nadiasvertex@gmail.com
Phabricator Review:
https://reviews.llvm.org/D99836

A couple of parallel patterns still remains serial - "Parallel partial sort", and "Parallel transform scan" - there are //TODOs in the code.
2021-10-15 15:36:07 +03:00
David Tenty 228b3b729d [libc++][AIX] Add scripts and config for building with the libcxx CI infrastructure
This initial change adds the AIX configuration to run-buildbot, an AIX
CMake cache file, and appropriate compiler and linker flags for testing
AIX to the lit "from scratch" configuration files. Either of the 32-bit or 64-bit configurations
can be built by setting `OBJECT_MODE` in the build environment (as is
typical for AIX).

Reviewed By: ldionne, #libc, #libc_abi

Differential Revision: https://reviews.llvm.org/D111244
2021-10-14 14:31:10 -04:00
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
Louis Dionne f6a74908a7 [runtimes] Add tests for vendor-specific properties
Vendors take libc++ and ship it in various ways. Some vendors might
ship it differently from what upstream LLVM does, i.e. the install
location might be different, some ABI properties might differ, etc.

In the past few years, I've come across several instances where
having a place to test some of these properties would have been
incredibly useful. I also just got bitten by the lack of tests
of that kind, so I'm adding some now.

The tests added by this commit for Apple platforms have numerous
TODOs that capture discrepancies between the upstream LLVM CMake
and the slightly-modified build we perform internally to produce
Apple's system libc++. In the future, the goal would be to upstream
all those differences so that it's possible to build a faithful
Apple system libc++ with the upstream LLVM sources only.

But this isn't only useful for Apple - this lays out the path for
any vendor being able to add their own checks (either upstream or
downstream) to libc++.

This is a re-application of 9892d1644f, which was reverted in 138dc27186
because it broke the build. The issue was that we didn't apply the required
changes to libunwind and our CI didn't notice it because we were not
running the libunwind tests. This has been fixed now, and we're running
the libunwind tests in CI now too.

Differential Revision: https://reviews.llvm.org/D110736
2021-10-07 15:46:20 -04:00
Haowei Wu 138dc27186 Revert "[libc++][libc++abi] Add tests for vendor-specific properties"
This reverts commit 9892d1644f, which
causes clang test failures in libcxx tests.
2021-09-30 11:03:59 -07:00
Louis Dionne 9892d1644f [libc++][libc++abi] Add tests for vendor-specific properties
Vendors take libc++ and ship it in various ways. Some vendors might
ship it differently from what upstream LLVM does, i.e. the install
location might be different, some ABI properties might differ, etc.

In the past few years, I've come across several instances where
having a place to test some of these properties would have been
incredibly useful. I also just got bitten by the lack of tests
of that kind, so I'm adding some now.

The tests added by this commit for Apple platforms have numerous
TODOs that capture discrepancies between the upstream LLVM CMake
and the slightly-modified build we perform internally to produce
Apple's system libc++. In the future, the goal would be to upstream
all those differences so that it's possible to build a faithful
Apple system libc++ with the upstream LLVM sources only.

But this isn't only useful for Apple - this lays out the path for
any vendor being able to add their own checks (either upstream or
downstream) to libc++.

Differential Revision: https://reviews.llvm.org/D110736
2021-09-29 17:22:37 -04:00
Alfonso Gregory a2c319fdc6 [LLVM][CMake][NFC] Resolve FIXME: Rename LLVM_CMAKE_PATH to LLVM_CMAKE_DIR throughout the project
This way, we do not need to set LLVM_CMAKE_PATH to LLVM_CMAKE_DIR when (NOT LLVM_CONFIG_FOUND)

Reviewed By: #libc, ldionne

Differential Revision: https://reviews.llvm.org/D107717
2021-09-16 18:29:57 +02:00
Nehal J Wani 1613ab8a4a [libcxx][libcxxabi] CMAKE_REQUIRED_FLAGS is a string, not a list
When `libcxx` or `libcxxabi` is built with `-DLLVM_USE_SANITIZER=MemoryWithOrigins`
**and** `-DLIBCXX[ABI]_USE_COMPILER_RT=ON`, all of the `LIBCXX[ABI]_SUPPORTS_*_FLAG`
checks fail, since the value of `CMAKE_REQUIRED_FLAGS` is not set correctly.

Bugzilla: https://bugs.llvm.org/show_bug.cgi?id=51774

Reviewed By: #libc, #libc_abi, compnerd, ldionne

Differential Revision: https://reviews.llvm.org/D109342
2021-09-16 18:26:29 +02:00
Martin Storsjö a3870e8ab1 Reapply [runtimes] Set more paths when building runtimes standalone
These paths are needed when building with per-target runtime directories.

(It's possible to fix this by manually setting these when invoking
cmake, but one isn't supposed to need to do that.)

Also set LLVM_TOOLS_BINARY_DIR while touching this area (as it's
also unset in this case) even if it isn't specifically needed by the
per-target runtime configuration.

Fixed since previous attempt: Don't check if the runtimes directory
is the root of the CMake invocation; when the main LLVM CMake
build builds runtimes, it does invoke a sub-CMake with this directory
as the root too, just as if manually invoking CMake at the runtimes
directory. Instead check whether LLVM_TOOLS_BINARY_DIR was set and
whether find_package(LLVM) succeeded or not.

Differential Revision: https://reviews.llvm.org/D107895
2021-09-09 15:30:42 +03:00
Leonard Chan d96e0c5388 Revert "[runtimes] Set more paths when building runtimes standalone"
This reverts commit 407e07aa67.

Reverting since this seems to break OpenMP builds and our clang
builders. See thread on https://reviews.llvm.org/D107895.
2021-09-08 18:31:10 -07:00
Martin Storsjö 407e07aa67 [runtimes] Set more paths when building runtimes standalone
These paths are needed when building with per-target runtime directories.

(It's possible to fix this by manually setting these when invoking
cmake, but one isn't supposed to need to do that.)

Also set LLVM_TOOLS_BINARY_DIR while touching this area (as it's
also unset in this case) even if it isn't specifically needed by the
per-target runtime configuration.

Differential Revision: https://reviews.llvm.org/D107895
2021-09-09 00:01:38 +03:00
Mark de Wever df2af9936c [libc++][format] Add a CMake Unicode option.
This option is used to select between the format headers output column
width option. This option should be independent of the locale setting.
It's encouraged to default to Unicode unless the platform doesn't offer
that option.

[format.string.std]/10
```
  For the purposes of width computation, a string is assumed to be in a
  locale-independent, implementation-defined encoding. Implementations
  should use a Unicode encoding on platforms capable of displaying Unicode
```

Reviewed By: #libc, ldionne, vitaut

Differential Revision: https://reviews.llvm.org/D103379
2021-09-04 11:55:10 +02:00
Mark de Wever 71909de374 [libc++] Disable incomplete library features.
Adds a new CMake option to disable the usage of incomplete headers.
These incomplete headers are not guaranteed to be ABI stable. This
option is intended to be used by vendors so they can avoid their users
from code that's not ready for production usage.

The option is enabled by default.

Differential Revision: https://reviews.llvm.org/D106763
2021-07-27 22:37:35 +02:00
Louis Dionne 069428b6f7 [libc++] Set the target triple by default in the standalone build
Even though the standalone build is deprecated, some people are still
relying on it (including libc++ itself for some configurations). Setting
the target triple will ensure that the build and the test suite behaves
consistently in the standalone and normal builds.

Differential Revision: https://reviews.llvm.org/D106800
2021-07-26 15:04:45 -04:00
Louis Dionne a59165b017 [runtimes] Don't try passing --target flags to GCC
When a target triple is specified in CMake via XXX_TARGET_TRIPLE, we tried
passing the --target=<...> flag to the compiler. However, not all compilers
support that flag (e.g. GCC, which is not a cross-compiler). As a result,
setting e.g. LIBCXX_TARGET_TRIPLE=<host-triple> would end up trying to
pass --target=<host-triple> to GCC, which breaks everything because the
flag isn't even supported.

This commit only adds `--target=<...>` & friends to the flags if it is
supported by the compiler.

One could argue that it's confusing to pass LIBCXX_TARGET_TRIPLE=<...>
and have it be ignored. That's correct, and one possibility would be
to assert that the requested triple is the same as the host triple when
we know the compiler is unable to cross-compile. However, note that this
is a pre-existing issue (setting the TARGET_TRIPLE variable never had an
influence on the flags passed to the compiler), and also fixing that is
starting to look like reimplementing a lot of CMake logic that is already
handled with CMAKE_CXX_COMPILER_TARGET.

Differential Revision: https://reviews.llvm.org/D106082
2021-07-15 16:52:02 -04:00
Louis Dionne a0ae3b0789 [libc++abi] Remove the LIBCXXABI_ENABLE_PIC option
Instead, people should be using CMAKE_POSITION_INDEPENDENT_CODE to control
whether they want to use PIC or not. We should try to avoid reinventing
the wheel whenever CMake natively supports something.

This makes libc++abi consistent with libc++ and libunwind.

Differential Revision: https://reviews.llvm.org/D103973
2021-06-10 12:26:31 -04:00
Louis Dionne b648c611ed [libc++] Fix libc++ build with assertions enabled
This fixes http://llvm.org/PR50534. This is another take on D103960
which is less disruptive.

Differential Revision: https://reviews.llvm.org/D103964
2021-06-09 12:58:53 -04:00
Louis Dionne 4d680b06c9 [libc++] Add a CI configuration for the modular build
Differential Revision: https://reviews.llvm.org/D103559
2021-06-08 13:32:08 -04:00
Louis Dionne 56b6e4e2df [libc++] Also build the static library in the Apple cache 2021-06-03 18:15:20 -04:00
Louis Dionne b274728b1a [libc++] Switch a few CI jobs to the minimal Lit configuration
Eventually, this should become the default way of running the tests.
For now, only move a few CI nodes to it, and keep a node that runs the
legacy configuration.

Differential Revision: https://reviews.llvm.org/D97565
2021-05-20 10:46:59 -04:00
Arthur O'Dwyer 86d1f590c2 [libc++] [test] Add a debug-mode CI.
To run llvm-lit manually from the command line:

    ./bin/llvm-lit -sv --param std=c++2b --param cxx_under_test=`pwd`/bin/clang \
        --param debug_level=1 ../libcxx/test/

Tests that currently fail with `debug_level=1` are marked `LIBCXX-DEBUG-FIXME`,
but my intent is to deal with all of them and leave no such annotations in
the codebase within the next couple weeks. (I have patches for all of them
in my local checkout.)

Differential Revision: https://reviews.llvm.org/D100866
2021-04-30 18:08:09 -04:00
Petr Hosek eea5cbc858 [libcxx] Fix the libc++abi header path
This addresses an issue introduced in 775e55462a.
2021-04-27 23:30:53 -07:00
Louis Dionne 8508b1c133 [libc++] Divorce the std Lit feature from the -std=XXX compiler flag
After this patch, we can use `--param std=c++20` even if the compiler only
supports -std=c++2a. The test suite will handle that for us. The only Lit
feature that isn't fully baked will always be the "in development" one,
since we don't know exactly what year the standard will be ratified in.

This is another take on https://reviews.llvm.org/D99789.

Differential Revision: https://reviews.llvm.org/D100210
2021-04-12 11:55:39 -04:00
Petr Hosek 96d8c6b571 [CMake] Remove {LIBCXX,LIBCXXABI,LIBUNWIND}_INSTALL_PREFIX
These variables were introduced during early work on the runtimes build
but were obsoleted by {LIBCXX,LIBCXXABI,LIBUNWIND}_INSTALL_LIBRARY_DIR.

Differential Revision: https://reviews.llvm.org/D99697
2021-04-01 10:13:07 -07:00
Louis Dionne c06a8f9caa [libc++] Include <__config_site> from <__config>
Prior to this patch, we would generate a fancy <__config> header by
concatenating <__config_site> and <__config>. This complexifies the
build system and also increases the difference between what's tested
and what's actually installed.

This patch removes that complexity and instead simply installs <__config_site>
alongside the libc++ headers. <__config_site> is then included by <__config>,
which is much simpler. Doing this also opens the door to having different
<__config_site> headers depending on the target, which was impossible before.

It does change the workflow for testing header-only changes to libc++.
Previously, we would run `lit` against the headers in libcxx/include.
After this patch, we run it against a fake installation root of the
headers (containing a proper <__config_site> header). This makes use
closer to testing what we actually install, which is good, however it
does mean that we have to update that root before testing header changes.
Thus, we now need to run `ninja check-cxx-deps` before running `lit` by
hand.

Differential Revision: https://reviews.llvm.org/D97572
2021-03-30 14:06:11 -07:00
Louis Dionne c504c68fac [libc++] Add a CI configuration with static libc++/libc++abi
Differential Revision: https://reviews.llvm.org/D99268
2021-03-24 16:30:48 -04:00
Louis Dionne 6c93eb4477 [libc++] Remove old cache file that was left behind by accident 2021-03-23 14:15:48 -04:00
Louis Dionne 2e033b36bf [libc++] NFC: nodebug => no-debug in the CI configurations 2021-03-23 14:10:27 -04:00
David Spickett 3aa6a4cb39 [libcxx][Arm] Move buildbot flags into cmake files
Reviewed By: #libc, Mordante, curdeius

Differential Revision: https://reviews.llvm.org/D98771
2021-03-19 16:45:09 +00:00
David Spickett 44e36fc2b1 [libcxx] Move Linaro 32 bit armv bots to buildkite
Instead of setting mcpu like the previous bots,
set the target triple.

Each config builds either Arm only or Thumb only
code. This gives us some coverage of thumb specific
issues.

The new agents on Linaro's side are running on v8 hardware
so will report arch "armv8l" just like the v8 bots.
(and buildkite can choose any of them for v7/v8 jobs)

Reviewed By: #libc, curdeius, Mordante

Differential Revision: https://reviews.llvm.org/D98019
2021-03-12 09:47:07 +00:00
David Spickett 6e5342a6b0 [libcxx] Move Linaro AArch64 buildbots to buildkite
Reviewed By: #libc, ldionne

Differential Revision: https://reviews.llvm.org/D96267
2021-03-04 10:22:17 +00:00
Zbigniew Sarbinowski 5f9be2c3e3 [SystemZ][ZOS] Prefer -nostdlib++ as opposed to -nodefaultlibs when building c++ libraries
Let's use -nostdlib++ rather than -nodefaultlibs when building libc++/libc++abi/libunwind libraries. The default is -nostdlib++ if supported by a build compiler like it is the case with clang, otherwise -nodefaultlibs is used as before.

This change is needed to avoid additional changes at the link step and not to increase the maintenance costs. If clang with -nodefaultlibs is used all the libraries which are removed but required would have to be manually added in. This set of libraries are unique and will send out.

The propose change will allow to make the link step simple for other platforms as well.

Reviewed By: #libc, #libc_abi, ldionne

Differential Revision: https://reviews.llvm.org/D95875
2021-02-16 18:42:14 +00:00
Dimitry Andric 328261019f Define new/delete in libc++ when using libcxxrt
Always turn on LIBCXX_ENABLE_NEW_DELETE_DEFINITIONS, if libcxxrt is used
as the C++ ABI library, since libcxxrt does not provide the full set
ofnew and delete operators. In particular, the aligned versions of these
operators are completely missing. This primarily addresses builds on
FreeBSD, as this platform uses libcxxrt by default.

Also, attempt to provide a FreeBSD.cmake cache file, with hopefully sane
settings, partially copied from the Apple.cmake cache file. This needs
more work, probably some additions to ci build scripts (although I am
not aware of any 'official' FreeBSD build bots).

Reviewed By: ldionne, #libc

Differential Revision: https://reviews.llvm.org/D96720
2021-02-15 21:22:12 +01:00
Louis Dionne 933518fff8 [libc++] Make LIBCXX_ENABLE_FILESYSTEM fully consistent
Previously, LIBCXX_ENABLE_FILESYSTEM controlled only whether the filesystem
support was compiled into libc++'s library. This commit promotes the
setting to a first-class option like LIBCXX_ENABLE_LOCALIZATION, where
the whole library is aware of the setting and features that depend on
<filesystem> won't be provided at all. The test suite is also properly
annotated such that tests that depend on <filesystem> are disabled when
the library doesn't support it.

This is an alternative to https://llvm.org/D94824, but also an improvement
along the lines of LIBCXX_ENABLE_LOCALIZATION that I had been wanting to
make for a while.

Differential Revision: https://reviews.llvm.org/D94921
2021-01-19 14:15:48 -05:00
Marek Kurdej 95729f95d8 [libc++] Add basic support for -std=c++2b.
* Add feature test macros.
* Add buildbot configuration generic-cxx2b that uses clang-tot.

Reviewed By: ldionne, #libc

Differential Revision: https://reviews.llvm.org/D94227
2021-01-08 19:02:41 +01:00
Marek Kurdej 044b892c79 [libc++] Use c++20 instead of c++2a consistently.
* The only exception is that the flag -std=c++2a is still used not to break compatibility with older compilers (clang <= 9, gcc <= 9).
* Bump _LIBCPP_STD_VER for C++20 to 20 and use 21 for the future standard (C++2b).

That's a preparation step to add c++2b support to libc++.

Reviewed By: ldionne, #libc

Differential Revision: https://reviews.llvm.org/D93383
2021-01-07 13:11:33 +01:00
Louis Dionne be00e8893f [libc++] Clarify how we pick the typeinfo comparison
This commit makes it clear that the typeinfo comparison implementation
is automatically selected by default, and that the CMake option only
overrides the value. This has been a source of confusion and bugs ever
since we've introduced complexity in that area, so I'm trying to simplify
it while still allowing for some control on the implementation.

Differential Revision: https://reviews.llvm.org/D91574
2020-11-18 16:58:45 -05:00
Louis Dionne 2eadbc8614 [libc++] Rework the whole availability markup implementation
Currently, vendor-specific availability markup is enabled by default.
This means that even when building against trunk libc++, the headers
will by default prevent you from using some features that were not
released in the dylib on your target platform. This is a source of
frustration since people building libc++ from sources are usually not
trying to use some vendor's released dylib.

For that reason, I've been thinking for a long time that availability
annotations should be off by default, which is the primary change that
this commit enables.

In addition, it reworks the implementation to make it easier for new
vendors to add availability annotations for their platform, and it
refreshes the documentation to reflect the current state of the codebase.

Finally, a CMake configuration option is added to control whether
availability annotations should be turned on for the flavor of libc++
being created. The intent is for vendors like Apple to turn it on, and
for the upstream libc++ to leave it off (the default).

Differential Revision: https://reviews.llvm.org/D90843
2020-11-05 12:28:52 -05:00
Louis Dionne 88ffc72717 [libc++] Add a libc++ configuration that does not support localization
When porting libc++ to embedded systems, it can be useful to drop support
for localization, which these systems don't implement or care about.

Differential Revision: https://reviews.llvm.org/D90072
2020-10-27 14:56:30 -04:00