Summary:
Freestanding is *weird*. The standard allows it to differ in a bunch of odd
manners from regular C++, and the committee would like to improve that
situation. I'd like to make libc++ behave better with what freestanding should
be, so that it can be a tool we use in improving the standard. To do that we
need to try stuff out, both with "freestanding the language mode" and
"freestanding the library subset".
Let's start with the super basic: run the libc++ tests in freestanding, using
clang as the compiler, and see what works. The easiest hack to do this:
In utils/libcxx/test/config.py add:
self.cxx.compile_flags += ['-ffreestanding']
Run the tests and they all fail.
Why? Because in freestanding `main` isn't special. This "not special" property
has two effects: main doesn't get mangled, and main isn't allowed to omit its
`return` statement. The first means main gets mangled and the linker can't
create a valid executable for us to test. The second means we spew out warnings
(ew) and the compiler doesn't insert the `return` we omitted, and main just
falls of the end and does whatever undefined behavior (if you're luck, ud2
leading to non-zero return code).
Let's start my work with the basics. This patch changes all libc++ tests to
declare `main` as `int main(int, char**` so it mangles consistently (enabling us
to declare another `extern "C"` main for freestanding which calls the mangled
one), and adds `return 0;` to all places where it was missing. This touches 6124
files, and I apologize.
The former was done with The Magic Of Sed.
The later was done with a (not quite correct but decent) clang tool:
https://gist.github.com/jfbastien/793819ff360baa845483dde81170feed
This works for most tests, though I did have to adjust a few places when e.g.
the test runs with `-x c`, macros are used for main (such as for the filesystem
tests), etc.
Once this is in we can create a freestanding bot which will prevent further
regressions. After that, we can start the real work of supporting C++
freestanding fairly well in libc++.
<rdar://problem/47754795>
Reviewers: ldionne, mclow.lists, EricWF
Subscribers: christof, jkorous, dexonsmith, arphaman, miyuki, libcxx-commits
Differential Revision: https://reviews.llvm.org/D57624
llvm-svn: 353086
to reflect the new license. These used slightly different spellings that
defeated my regular expressions.
We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.
Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.
llvm-svn: 351648
The tests were marked to fail based on the 'availability' LIT feature.
However, those tests should really only be failing when we run them
against the dylibs that were deployed on macosx10.7 and macosx10.8,
which the deployment target has nothing to do with.
This caused the tests to unexpectedly pass when running the tests
with deployment target macosx10.{7,8} but running with a recent dylib.
llvm-svn: 348520
Libc++ is used as a system library on macOS and iOS (amongst others). In order
for users to be able to compile a binary that is intended to be deployed to an
older version of the platform, clang provides the
availability attribute <https://clang.llvm.org/docs/AttributeReference.html#availability>_
that can be placed on declarations to describe the lifecycle of a symbol in the
library.
See docs/DesignDocs/AvailabilityMarkup.rst for more information.
Differential Revision: https://reviews.llvm.org/D31739
llvm-svn: 302172
The tests for libc++ specify -target on the command-line to the
compiler, but this is problematic for a few reasons.
Firstly, the -target option isn't supported on Apple platforms. Parts
of the triple get dropped and ignored. Instead, software should be
compiled with a combination of the -arch and -m<name>-version-min
options.
Secondly, the generic "darwin" target references a kernel version
instead of a platform version. Each platform has its own independent
versions (with different versions of libc++.1.dylib), independent of the
version of the Darwin kernel.
This commit adds support to the LIT infrastructure for testing against
Apple platforms using -arch and -platform options.
If the host is not on OS X, or the compiler type is not clang or apple-clang, then this commit has NFC.
If the host is on OS X and --param=target_triple=... is specified, then a warning is emitted to use arch and platform instead. Besides the warning, there's NFC.
If the host is on OS X and *no* target-triple is specified, then use the new deployment target logic. This uses two new lit parameters, --param=arch=<arch> and --param=platform=<platform>. <platform> has the form <name>[<version>].
By default, arch is auto-detected from clang -dumpmachine, and platform is "macosx".
If the platform doesn't have a version:
For "macosx", the version is auto-detected from the host system using sw_vers. This may give a different version than the SDK, since new SDKs can be installed on older hosts.
Otherwise, the version is auto-detected from the SDK version using xcrun --show-sdk-path.
-arch <arch> -m<name>-version-min=<version> is added to the compiler flags.
The target triple is computed as <arch>-apple-<platform>. It is *not* passed to clang, but it is available for XFAIL and UNSUPPORTED (as is with_system_cxx_lib=<target>).
For convenience, apple-darwin and <arch>-apple-darwin are added to the set of available features.
There were a number of tests marked to XFAIL on x86_64-apple-darwin11
and x86_64-apple-darwin12. I updated these to
x86_64-apple-macosx10.7 and x86_64-apple-macosx10.8.
llvm-svn: 297798
