In D144319, Clang tried to land a change that would cause some functions
that are not supposed to return nullptr to optimize better. As reported
in https://reviews.llvm.org/D144319#4203982, libc++ started seeing
failures in its CI shortly after this change was landed.
As explained in D146379, the reason for these failures is that libc++'s
throwing `operator new` can in fact return nullptr when compiled with
exceptions disabled. However, this contradicts the Standard, which
clearly says that the throwing version of `operator new(size_t)` should
never return nullptr. This is actually a long standing issue. I've
previously seen a case where LTO would optimize incorrectly based on the
assumption that `operator new` doesn't return nullptr, an assumption
that was violated in that case because libc++.dylib was compiled with
-fno-exceptions.
Unfortunately, fixing this is kind of tricky. The Standard has a few
requirements for the allocation functions, some of which are impossible
to satisfy under -fno-exceptions:
1. `operator new(size_t)` must never return nullptr
2. `operator new(size_t, nothrow_t)` must call the throwing version and
return nullptr on failure to allocate
3. We can't throw exceptions when compiled with -fno-exceptions
In the case where exceptions are enabled, things work nicely.
`new(size_t)` throws and `new(size_t, nothrow_t)` uses a try-catch to
return nullptr. However, when compiling the library with
-fno-exceptions, we can't throw an exception from `new(size_t)`, and we
can't catch anything from `new(size_t, nothrow_t)`. The only thing we
can do from `new(size_t)` is actually abort the program, which does not
make it possible for `new(size_t, nothrow_t)` to catch something and
return nullptr.
This patch makes the following changes:
1. When compiled with -fno-exceptions, the throwing version of `operator
new` will now abort on failure instead of returning nullptr on failure.
This resolves the issue that the compiler could mis-compile based on the
assumption that nullptr is never returned. This constitutes an API and
ABI breaking change for folks compiling the library with -fno-exceptions
(which is not the general public, who merely uses libc++ headers but use
a shared library that has already been compiled). This should mostly
impact vendors and other folks who compile libc++.dylib themselves.
2. When the library is compiled with -fexceptions, the nothrow version
of `operator new` has no change. When the library is compiled with
-fno-exceptions, the nothrow version of `operator new` will now check
whether the throwing version of `operator new` has been overridden. If
it has not been overridden, then it will use an implementation
equivalent to that of the throwing `operator new`, except it will return
nullptr on failure to allocate (instead of terminating). However, if the
throwing `operator new` has been overridden, it is now an error NOT to
also override the nothrow `operator new`. Indeed, there is no way for us
to implement a valid nothrow `operator new` without knowing the exact
implementation of the throwing version.
In summary, this change will impact people who fall into the following
intersection of conditions:
- They use the libc++ shared/static library built with `-fno-exceptions`
- They do not override `operator new(..., std::nothrow_t)`
- They override `operator new(...)` (the throwing version)
- They use `operator new(..., std::nothrow_t)`
We believe this represents a small number of people.
Fixes#60129
rdar://103958777
Differential Revision: https://reviews.llvm.org/D150610
This patch removes the noexcept specifier introduced in #69407 since the
Standard allows a new handler to throw an exception of type bad_alloc
(or derived from it). With the noexcept specifier on the helper
functions, we would immediately terminate the program.
The patch also adds tests for the case that had regressed.
Co-authored-by: Alison Zhang <alisonzhang@ibm.com>
This patch adds a configuration of the libc++ test suite that enables
optimizations when building the tests. It also adds a new CI
configuration to exercise this on a regular basis. This is added in the
context of [1], which requires building with optimizations in order to
hit the bug.
[1]: https://github.com/llvm/llvm-project/issues/68552
Found while running libc++'s tests with MSVC's STL.
*
`libcxx/test/std/algorithms/alg.sorting/alg.heap.operations/sort.heap/ranges_sort_heap.pass.cpp`
+ Fix Clang `-Wunused-variable`, because `LIBCPP_ASSERT` expands to
nothing for MSVC's STL.
+ This is the same "always void-cast" change that #73437 applied to the
neighboring `complexity.pass.cpp`. I missed that
`ranges_sort_heap.pass.cpp` was also affected because we had disabled
this test.
*
`libcxx/test/std/input.output/file.streams/fstreams/ifstream.members/buffered_reads.pass.cpp`
*
`libcxx/test/std/input.output/file.streams/fstreams/ofstream.members/buffered_writes.pass.cpp`
+ Fix MSVC "warning C4244: '`=`': conversion from '`__int64`' to
'`_Ty`', possible loss of data".
+ This is a valid warning, possibly the best one that MSVC found in this
entire saga. We're accumulating a `std::vector<std::streamsize>` and
storing the result in `std::streamsize total_size` but we actually have
to start with `std::streamsize{0}` or we'll truncate.
*
`libcxx/test/std/input.output/filesystems/fs.enum/enum.path.format.pass.cpp`
+ Fix Clang `-Wunused-local-typedef` because the following usage is
libc++-only.
+ I'm just expanding it at the point of use, and using the dedicated
`LIBCPP_STATIC_ASSERT` to keep the line length down.
*
`libcxx/test/std/input.output/syncstream/syncbuf/syncstream.syncbuf.assign/swap.pass.cpp`
+ Fix MSVC "warning C4242: 'argument': conversion from '`int`' to
'`const _Elem`', possible loss of data".
+ This is a valid warning (possibly the second-best) as `sputc()`
returns `int_type`. If `sputc()` returns something unexpected, we want
to know, so we should separately say `expected.push_back(CharT('B'))`.
*
`libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new.size_align_nothrow.pass.cpp`
*
`libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new.size_nothrow.pass.cpp`
+ Fix MSVC "warning C6001: Using uninitialized memory '`x`'."
+ [N4964](https://wg21.link/N4964) \[new.delete.single\]/12:
> *Effects:* The deallocation functions
(\[basic.stc.dynamic.deallocation\]) called by a *delete-expression*
(\[expr.delete\]) to render the value of `ptr` invalid.
+ \[basic.stc.general\]/4:
> When the end of the duration of a region of storage is reached, the
values of all pointers representing the address of any part of that
region of storage become invalid pointer values (\[basic.compound\]).
Indirection through an invalid pointer value and passing an invalid
pointer value to a deallocation function have undefined behavior. Any
other use of an invalid pointer value has implementation-defined
behavior.
+ In certain configurations, after `delete x;` MSVC will consider `x` to
be radioactive (and in other configurations, it'll physically null out
`x` as a safety measure). We can copy it into `old_x` before deletion,
which the implementation finds acceptable.
*
`libcxx/test/std/ranges/range.adaptors/range.elements/general.pass.cpp`
*
`libcxx/test/std/ranges/range.adaptors/range.elements/iterator/deref.pass.cpp`
+ Fix MSVC "warning C4242: 'initializing': conversion from '`_Ty`' to
'`_Ty`', possible loss of data".
+ This was being emitted in `pair` and `tuple`'s perfect forwarding
constructors. Passing `short{1}` allows MSVC to see that no truncation
is happening.
*
`libcxx/test/std/ranges/range.adaptors/range.elements/iterator/member_types.compile.pass.cpp`
+ Fix MSVC "warning C4242: 'initializing': conversion from '`_Ty`' to
'`_Ty2`', possible loss of data".
+ Similarly, this was being emitted in `pair`'s perfect forwarding
constructor. After passing `short{1}`, I reduced repetition by relying
on CTAD. (I can undo that cleanup if it's stylistically undesirable.)
*
`libcxx/test/std/utilities/function.objects/refwrap/refwrap.const/type_conv_ctor.pass.cpp`
+ Fix MSVC "warning C4930: '`std::reference_wrapper<int> purr(void)`':
prototyped function not called (was a variable definition intended?)".
+ There's no reason for `purr()` to be locally declared (aside from
isolating it to a narrow scope, which has minimal benefits); it can be
declared like `meow()` above. 😸
*
`libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.create/make_shared_for_overwrite.pass.cpp`
*
`libcxx/test/std/utilities/smartptr/unique.ptr/unique.ptr.create/make_unique_for_overwrite.default_init.pass.cpp`
+ Fix MSVC static analysis warnings when replacing `operator new`:
```
warning C28196: The requirement that '(_Param_(1)>0)?(return!=0):(1)' is
not satisfied. (The expression does not evaluate to true.)
warning C6387: 'return' could be '0': this does not adhere to the
specification for the function 'new'.
warning C6011: Dereferencing NULL pointer 'reinterpret_cast<char
*>ptr+i'.
```
+ All we need is a null check, which appears in other `operator new`
replacements:
b85f1f9b18/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new.size.replace.pass.cpp (L27-L28)
This patch actually runs the tests for picolibc behind an emulator,
removing a few workarounds and increasing coverage.
Differential Revision: https://reviews.llvm.org/D155521
Picolibc is a C Standard Library that is commonly used in embedded
environments. This patch adds initial support for this configuration
along with pre-commit CI. As of this patch, the test suite only builds
the tests and nothing is run. A follow-up patch will make the test suite
actually run the tests.
Differential Revision: https://reviews.llvm.org/D154246
According to https://developer.apple.com/support/xcode/, quite a few of
our availability macros don't do anything anymore, so we might as well
remove them to clean up the code a bit.
AppleClang 15 was released on September 18th and is now stable. Per our
policy, we're bumping the supported AppleClang compiler to the latest
release. This allows cleaning up the test suite, but most importantly
unblocking various other patches that are blocked on bumping the
compiler requirements.
Since C++14 has been released for about nine years and most standard
libraries have implemented sized deallocation functions, it's time to
make this feature default again.
Reviewed By: rnk, aaron.ballman, #libc, ldionne, Mordante, MaskRay
Differential Revision: https://reviews.llvm.org/D112921
The oldest deployment target supported by Xcode 14 is macOS 10.13.
Trying to back-deploy to older targets runs into other issues in Clang,
so stop testing libc++ against unsupported deployment targets.
This patch doesn't attempt to clean up support for older deployment
targets from the code base -- this will be done in a follow-up patch.
Differential Revision: https://reviews.llvm.org/D155085
I made sure they all had some expected-error output in them. Many of
these tests would be better implemented as a positive test using SFINAE,
but this is beyond the scope of this patch.
Differential Revision: https://reviews.llvm.org/D153980
A few tests were also straightforward to translate to SFINAE tests
instead, so in a few cases I did that and removed the .fail.cpp test
entirely.
Differential Revision: https://reviews.llvm.org/D153149
Use ASSERT_WITH_OPERATOR_NEW_FALLBACKS where relevant to waive
the known cases where operator new isn't overridden as expected,
in MinGW DLL configurations.
Clarify the reason for why the fallback in
new.delete.array/new.size_align_nothrow.replace.indirect doesn't
work as expected, which can be considered a vcruntime bug.
Differential Revision: https://reviews.llvm.org/D151304
I stumbled upon the `operator new` and `operator new[]` tests while
investigating an issue with `operator new` when exceptions are disabled,
and I realized that our test coverage was incomplete. This patch refactors
all the `operator new` and `operator new[]` tests to add consistency and
better coverage for scenarios in which it should be possible to override
an operator indirectly by defining another one (for example new(size_t, nothrow)
should use new(size_t) if it has been provided).
This is intended to be a NFC setting up the terrain for some refactoring
work and bug fix in operator new.
Differential Revision: https://reviews.llvm.org/D150408
The use_system_cxx_lib Lit feature was only used for back-deployment
testing. However, one immense hole in that setup was that we didn't
have a proper way to test Apple's own libc++ outside of back-deployment,
which was embodied by the fact that we needed to define _LIBCPP_DISABLE_AVAILABILITY
when testing (see change in libcxx/utils/libcxx/test/params.py).
This led to the apple-system testing configuration not checking for
availability markup, which is obviously quite bad since the library
we ship actually has availability markup.
Using stdlib=<VENDOR>-libc++ instead to encode back-deployment restrictions
on tests is simpler and it makes it possible to naturally support tests
such as availability markup checking even in the tip-of-trunk Apple-libc++
configuration.
Differential Revision: https://reviews.llvm.org/D146366
Instead of writing something like `XFAIL: use_system_cxx_lib && target=...`
to XFAIL back-deployment tests, introduce named Lit features like
`availability-shared_mutex-missing` to represent those. This makes the
XFAIL annotations leaner, and solves the problem of XFAIL comments
potentially getting out of sync. This would also make it easier for
another vendor to add their own annotations to the test suite by simply
changing how the feature is defined for their OS releases, instead
of having to modify hundreds of tests to add repetitive annotations.
This doesn't touch *all* annotations -- only annotations that were widely
duplicated are given named features (e.g. when filesystem or shared_mutex
were introduced). I still think it probably doesn't make sense to have a
named feature for every single fix we make to the dylib.
This is in essence a revert of 2659663, but since then the test suite
has changed significantly. Back when I did 2659663, the configuration
files we have for the test suite right now were being bootstrapped and
it wasn't clear how to provide these features for back-deployment in
that context. Since then, we have a streamlined way of defining these
features in `features.py` and that doesn't impact the ability for a
configuration file to stay minimal.
The original motivation for this change was that I am about to propose
a change that would touch essentially all XFAIL annotations for back-deployment
in the test suite, and this greatly reduces the number of lines changed
by that upcoming change, in addition to making the test suite generally
better.
Differential Revision: https://reviews.llvm.org/D146359
We pretty consistently don't define those cause they are not needed,
and it removes the potential pitfall to think that these tests are
being run. This doesn't touch .compile.fail.cpp tests since those
should be replaced by .verify.cpp tests anyway, and there would be
a lot to fix up.
As a fly-by, I also fixed a bit of formatting, removed a few unused
includes and made some very minor, clearly NFC refactorings such as
in allocator.traits/allocator.traits.members/allocate.verify.cpp where
the old test basically made no sense the way it was written.
Differential Revision: https://reviews.llvm.org/D146236
Adding `[[nodiscard]]` to functions is a conforming extension and done extensively in the MSVC STL.
Reviewed By: ldionne, EricWF, #libc
Spies: #libc_vendors, cjdb, mgrang, jloser, libcxx-commits
Differential Revision: https://reviews.llvm.org/D128267
This patch rewords the static assert diagnostic output. Failing a
_Static_assert in C should not report that static_assert failed. This
changes the wording to be more like GCC and uses "static assertion"
when possible instead of hard coding the name. This also changes some
instances of 'static_assert' to instead be based on the token in the
source code.
Differential Revision: https://reviews.llvm.org/D129048
Looks like we again are going to have problems with libcxx tests that
are overly specific in their dependency on clang's diagnostics.
This reverts commit 6542cb55a3.
This patch is basically the rewording of the static assert statement's
output(error) on screen after failing. Failing a _Static_assert in C
should not report that static_assert failed. It’d probably be better to
reword the diagnostic to be more like GCC and say “static assertion”
failed in both C and C++.
consider a c file having code
_Static_assert(0, "oh no!");
In clang the output is like:
<source>:1:1: error: static_assert failed: oh no!
_Static_assert(0, "oh no!");
^ ~
1 error generated.
Compiler returned: 1
Thus here the "static_assert" is not much good, it will be better to
reword it to the "static assertion failed" to more generic. as the gcc
prints as:
<source>:1:1: error: static assertion failed: "oh no!"
1 | _Static_assert(0, "oh no!");
| ^~~~~~~~~~~~~~
Compiler returned: 1
The above can also be seen here. This patch is about rewording
the static_assert to static assertion.
Differential Revision: https://reviews.llvm.org/D129048
After checking the libc++abi.dylib shipped in macOS 10.13, I can confirm
that it contains the align_val_t variants of operator new and operator
delete. However, the libc++abi.dylib shipped on macOS 10.12 does not.
Differential Revision: https://reviews.llvm.org/D129198
Display 'static_assert failed: message' instead of
'static_assert failed "message"' to be consistent
with other implementations and be slightly more
readable.
Reviewed By: #libc, aaron.ballman, philnik, Mordante
Differential Revision: https://reviews.llvm.org/D128844
`__GCC_CONSTRUCTIVE_SIZE` and `__GCC_DESTRUCTIVE_SIZE` are available since GCC 12. I'm assuming clang will also implement these for compatability with libstdc++.
Reviewed By: ldionne, #libc
Spies: h-vetinari, libcxx-commits, arichardson
Differential Revision: https://reviews.llvm.org/D122276
This changes adds the pipeline config for both 32-bit and 64-bit AIX targets. As well, we add a lit feature `LIBCXX-AIX-FIXME` which is used to mark the failing tests which remain to be investigated on AIX, so that the CI produces a clean build.
Reviewed By: #libc, ldionne
Differential Revision: https://reviews.llvm.org/D111359
Even if these comments have a benefit in .h files (for editors that
care about language but can't be configured to treat .h as C++ code),
they certainly have no benefit for files with the .cpp extension.
Discussed in D110794.
Since we officially don't support several older compilers now, we can
drop a lot of the markup in the test suite. This helps keep the test
suite simple and makes sure that UNSUPPORTED annotations don't rot.
This is the first patch of a series that will remove annotations for
compilers that are now unsupported.
Differential Revision: https://reviews.llvm.org/D107787
This allows waiving the right amount of asserts on Windows and zOS.
This should supersede D107124 and D105910.
Differential Revision: https://reviews.llvm.org/D107755
The XFAIL comments about VCRuntime not providing aligned operator new
are outdated; these days VCRuntime does provide them.
However, the tests used to fail on Windows, as the pointers allocated
with an aligned operator new (which is implemented with _aligned_malloc
on Windows) can't be freed using std::free() on Windows (but they need
to be freed with the corresponding function _aligned_free instead).
Instead override the aligned operator new to return a dummy suitably
aligned pointer instead, like other tests that override aligned operator
new.
Also override `operator delete[]` instead of plain `operator delete`
in the array testcase; the fallback from `operator delete[]` to
user defined `operator delete` doesn't work in all DLL build
configurations on Windows.
Also expand the TEST_NOEXCEPT macros, as these tests only are built
in C++17 mode.
By providing the aligned operator new within the tests, this also makes
these test cases pass when testing back deployment on macOS 10.9.
Differential Revision: https://reviews.llvm.org/D105962
Now that Lit supports regular expressions inside XFAIL & friends, it is
much easier to write Lit annotations based on the triple.
Differential Revision: https://reviews.llvm.org/D104747
This fixes a long standing issue where the triple is not always set
consistently in all configurations. This change also moves the
back-deployment Lit features to using the proper target triple
instead of using something ad-hoc.
This will be necessary for using from scratch Lit configuration files
in both normal testing and back-deployment testing.
Differential Revision: https://reviews.llvm.org/D102012
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
This matches what we link the library itself against (set in
CMakeLists.txt). When testing a static library version of libc++,
this is needed for essentially every test due to libc++ object files
requiring it.
Also with libc++ built as a DLL, some tests directly call functions that
are provided by msvcprt (such as std::set_new_handler), thus this fixes
a number of tests in that configuration too.
Differential Revision: https://reviews.llvm.org/D99263
This makes no attempt yet to look into the why/what for each of them,
but makes the CI configuration useful for tracking further regressions.
After looking into each case, they can either be fixed, or converted
into UNSUPPORTED: windows or XFAIL: windows, once the cause is known
and explained.
A number of the filesystem cases can be fixed by patches that are
currently in review.
Differential Revision: https://reviews.llvm.org/D99095
- Several -Wshadow warnings
- Several places where we did not initialize our base class explicitly
- Unused variable warnings
- Some tautological comparisons
- Some places where we'd pass null arguments to functions expecting
non-null (in unevaluated contexts)
- Add a few pragmas to turn off spurious warnings
- Fix warnings about declarations that don't declare anything
- Properly disable deprecation warnings in ext/ tests (the pragmas we
were using didn't work on GCC)
- Disable include_as_c.sh.cpp because GCC complains about C++ flags
when compiling as C. I couldn't find a way to fix this one properly,
so I'm disabling the test. This isn't great, but at least we'll be
able to enable warnings in the whole test suite with GCC.
This is needed when running the tests in Freestanding mode, where main()
isn't treated specially. In Freestanding, main() doesn't get mangled as
extern "C", so whatever runtime we're using fails to find the entry point.
One way to solve this problem is to define a symbol alias from __Z4mainiPPc
to _main, however this requires all definitions of main() to have the same
mangling. Hence this commit.
