[libc++] Properly guard std::filesystem with >= C++17 (#72701)

<filesystem> is a C++17 addition. In C++11 and C++14 modes, we actually
have all the code for <filesystem> but it is hidden behind a n

[libc++] Properly guard std::filesystem with >= C++17 (#72701)

<filesystem> is a C++17 addition. In C++11 and C++14 modes, we actually
have all the code for <filesystem> but it is hidden behind a non-inline
namespace __fs so it is not accessible. Instead of doing this unusual
dance, just guard the code for filesystem behind a classic C++17 check
like we normally do.

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[libc++] Expand the contents of LIBCXX_ENABLE_FILESYSTEM

Since LIBCXX_ENABLE_FILESYSTEM now truly represents whether the
platform supports a filesystem (as opposed to whether the <filesystem>
librar

[libc++] Expand the contents of LIBCXX_ENABLE_FILESYSTEM

Since LIBCXX_ENABLE_FILESYSTEM now truly represents whether the
platform supports a filesystem (as opposed to whether the <filesystem>
library is provided), we can provide a few additional classes from
the <filesystem> library even when the platform does not have support
for a filesystem. For example, this allows performing path manipulations
using std::filesystem::path even on platforms where there is no actual
filesystem.

rdar://107061236

Differential Revision: https://reviews.llvm.org/D152382

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[libc++] IWYU in <filesystem> tests

Add headers in `<filesystem>` tests that were transitively included
through `<filesystem>`

Reviewed as part of D116146

Revert "[libc++] Remove unused headers from <filesystem>"

This reverts commit 352945dd36c64fd68b4c73fcc393ee5828da639a.

[libc++] Remove unused headers from <filesystem>

Remove unused headers from `<filesystem>`

Spies: libcxx-commits

Differential Revision: https://reviews.llvm.org/D116146

[libcxx] [test] Fix string type handling in a few fairly trivial class.path tests

Use string() for convenience for testing where possible, but keep using
native() for move tests where we want to che

[libcxx] [test] Fix string type handling in a few fairly trivial class.path tests

Use string() for convenience for testing where possible, but keep using
native() for move tests where we want to check that no allocations are
made, constructing a reference fs::path::string_type instead.

Use the right value_type in a few places.

Make the synop test check for the right types and for the expected
preferred separator.

Differential Revision: https://reviews.llvm.org/D89537

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[libc++] Remove the c++98 Lit feature from the test suite

C++98 and C++03 are effectively aliases as far as Clang is concerned.
As such, allowing both std=c++98 and std=c++03 as Lit parameters is
ju

[libc++] Remove the c++98 Lit feature from the test suite

C++98 and C++03 are effectively aliases as far as Clang is concerned.
As such, allowing both std=c++98 and std=c++03 as Lit parameters is
just slightly confusing, but provides no value. It's similar to allowing
both std=c++17 and std=c++1z, which we don't do.

This was discovered because we had an internal bot that ran the test
suite under both c++98 AND c++03 -- one of which is redundant.

Differential Revision: https://reviews.llvm.org/D80926

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libcxx: Rename .hpp files in libcxx/test/support to .h

LLVM uses .h as its extension for header files.

Files renamed using:

for f in libcxx/test/support/*.hpp; do git mv $f ${f%.hpp}.h; done

libcxx: Rename .hpp files in libcxx/test/support to .h

LLVM uses .h as its extension for header files.

Files renamed using:

for f in libcxx/test/support/*.hpp; do git mv $f ${f%.hpp}.h; done

References to the files updated using:

for f in $(git diff master | grep 'rename from' | cut -f 3 -d ' '); do
a=$(basename $f);
echo $a;
rg -l $a libcxx | xargs sed -i '' "s/$a/${a%.hpp}.h/";
done

HPP include guards updated manually using:

for f in $(git diff master | grep 'rename from' | cut -f 3 -d ' '); do
echo ${f%.hpp}.h ;
done | xargs mvim

Differential Revision: https://reviews.llvm.org/D66104

llvm-svn: 369481

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Revert "[libc++] Build <filesystem> support as part of the dylib"

When I applied r356500 (https://reviews.llvm.org/D59152), I somehow
deleted all of filesystem's tests. I will revert r356500 and re-

Revert "[libc++] Build <filesystem> support as part of the dylib"

When I applied r356500 (https://reviews.llvm.org/D59152), I somehow
deleted all of filesystem's tests. I will revert r356500 and re-apply
it properly.

llvm-svn: 356505

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Support tests in freestanding

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

Support tests in freestanding

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

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Update more file headers across all of the LLVM projects in the monorepo
to reflect the new license. These used slightly different spellings that
defeated my regular expressions.

We understand that

Update more file headers across all of the LLVM projects in the monorepo
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

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Implement <filesystem>

This patch implements the <filesystem> header and uses that
to provide <experimental/filesystem>.

Unlike other standard headers, the symbols needed for <filesystem>
have not

Implement <filesystem>

This patch implements the <filesystem> header and uses that
to provide <experimental/filesystem>.

Unlike other standard headers, the symbols needed for <filesystem>
have not yet been placed in libc++.so. Instead they live in the
new libc++fs.a library. Users of filesystem are required to link this
library. (Also note that libc++experimental no longer contains the
definition of <experimental/filesystem>, which now requires linking libc++fs).

The reason for keeping <filesystem> out of the dylib for now is that
it's still somewhat experimental, and the possibility of requiring an
ABI breaking change is very real. In the future the symbols will likely
be moved into the dylib, or the dylib will be made to link libc++fs automagically).

Note that moving the symbols out of libc++experimental may break user builds
until they update to -lc++fs. This should be OK, because the experimental
library provides no stability guarantees. However, I plan on looking into
ways we can force libc++experimental to automagically link libc++fs.

In order to use a single implementation and set of tests for <filesystem>, it
has been placed in a special `__fs` namespace. This namespace is inline in
C++17 onward, but not before that. As such implementation is available
in C++11 onward, but no filesystem namespace is present "directly", and
as such name conflicts shouldn't occur in C++11 or C++14.

llvm-svn: 338093

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