In std::tuple, we should try to avoid calling std::is_copy_constructible
whenever we can to avoid surprising interactions with (I believe) compiler
builtins. This bug was reported in https://reviews.llvm.org/D96523#2730953.
The issue was that when tuple<_Up...> was the same as tuple<_Tp...>, we
would short-circuit the _Or (because sizeof...(_Tp) != 1) and go evaluate
the following `is_constructible<_Tp, const _Up&>...`. That shouldn't
actually be a problem, but see the analysis in https://reviews.llvm.org/D101770#2736470
for why it is with Clang and GCC.
Instead, after this patch, we check whether the constructed-from tuple
is the same as the current tuple regardless of the number of elements,
since we should always prefer the normal copy constructor in that case
anyway.
Differential Revision: https://reviews.llvm.org/D101770
This nasty patch rewrites the tuple constructors to match those defined
by the Standard. We were previously providing several extensions in those
constructors - those extensions are removed by this patch.
The issue with those extensions is that we've had numerous bugs filed
against us over the years for problems essentially caused by them. As a
result, people are unable to use tuple in ways that are blessed by the
Standard, all that for the perceived benefit of providing them extensions
that they never asked for.
Since this is an API break, I communicated it in the release notes.
I do not foresee major issues with this break because I don't think the
extensions are too widely relied upon, but we can ship it and see if we
get complaints before the next LLVM release - that will give us some
amount of information regarding how much use these extensions have.
Differential Revision: https://reviews.llvm.org/D96523
As mandated by the Standard's various synopses, e.g. [iterator.synopsis].
Searching the TeX source for '#include' is a good way to find all of these
mandates.
The new tests are all autogenerated by utils/generate_header_inclusion_tests.py.
I was SHOCKED by how many mandates there are, and how many of them
libc++ wasn't conforming with.
Differential Revision: https://reviews.llvm.org/D99309
The implementation of tuple's constructors and assignment operators
currently diverges from the way the Standard specifies them, which leads
to subtle cases where the behavior is not as specified. In particular, a
class derived from a tuple-like type (e.g. pair) can't be assigned to a
tuple with corresponding members, when it should. This commit re-implements
the assignment operators (BUT NOT THE CONSTRUCTORS) in a way much closer
to the specification to get rid of this bug. Most of the tests have been
stolen from Eric's patch https://reviews.llvm.org/D27606.
As a fly-by improvement, tests for noexcept correctness have been added
to all overloads of operator=. We should tackle the same issue for the
tuple constructors in a future patch - I'm just trying to make progress
on fixing this long-standing bug.
PR17550
rdar://15837420
Differential Revision: https://reviews.llvm.org/D50106
Summary:
LWG 3158 marks the allocator_arg_t constructor of std::tuple as
conditionnally explicit based on whether the default constructors
of the tuple's members are explicitly default constructible.
This was previously committed as r372778 and reverted in r372832 due to
the commit breaking LLVM's build in C++14 mode. This issue has now been
addressed.
Reviewers: mclow.lists
Subscribers: christof, jkorous, dexonsmith, libcxx-commits
Tags: #libc
Differential Revision: https://reviews.llvm.org/D65232
llvm-svn: 373092
Summary:
LWG2510 makes tag types like allocator_arg_t explicitly default
constructible instead of implicitly default constructible. It also
makes the constructors for std::pair and std::tuple conditionally
explicit based on the explicit-ness of the default constructibility
for the pair/tuple's elements.
This was previously committed as r372777 and reverted in r372832 due to
the commit breaking LLVM's build in C++14 mode. This issue has now been
addressed.
Reviewers: mclow.lists
Subscribers: christof, jkorous, dexonsmith, libcxx-commits
Tags: #libc
Differential Revision: https://reviews.llvm.org/D65161
llvm-svn: 372983
This also reverts:
- r372778: [libc++] Implement LWG 3158
- r372782: [libc++] Try fixing tests that fail on GCC 5 and older
- r372787: Purge mentions of GCC 4 from the test suite
Reason: the change breaks compilation of LLVM with libc++, for details see
http://lists.llvm.org/pipermail/libcxx-dev/2019-September/000599.html
llvm-svn: 372832
Summary:
LWG 3158 marks the allocator_arg_t constructor of std::tuple as
conditionnally explicit based on whether the default constructors
of the tuple's members are explicitly default constructible.
Reviewers: EricWF, mclow.lists
Subscribers: christof, jkorous, dexonsmith, libcxx-commits
Tags: #libc
Differential Revision: https://reviews.llvm.org/D65232
llvm-svn: 372778
Summary:
LWG2510 makes tag types like allocator_arg_t explicitly default
constructible instead of implicitly default constructible. It also
makes the constructors for std::pair and std::tuple conditionally
explicit based on the explicit-ness of the default constructibility
for the pair/tuple's elements.
Reviewers: mclow.lists, EricWF
Subscribers: christof, jkorous, dexonsmith, libcxx-commits
Tags: #libc
Differential Revision: https://reviews.llvm.org/D65161
llvm-svn: 372777
Summary:
We were using implicit deduction guides instead of explicit ones,
however the implicit ones don't do work anymore when changing the
constructors.
This commit adds the actual guides specified in the Standard to make
libc++ (1) closer to the Standard and (2) more resistent to changes
in std::tuple's constructors.
Reviewers: Quuxplusone
Subscribers: christof, jkorous, dexonsmith, libcxx-commits
Tags: #libc
Differential Revision: https://reviews.llvm.org/D65225
llvm-svn: 368599
The constructors for std::pair and std::tuple have been made conditionally
explicit, however the synopsis in the headers do not reflect that.
llvm-svn: 366735
Previously we implemented all one trillion tuple-like constructors using
a single generic overload. This worked fairly well, except that it
differed in behavior from the standard version because it didn't
consider both T&& and T const&. This was observable for certain
types.
This patch addresses that issue by splitting the generic constructor
in two. We now provide both T&& and T const& versions of the
tuple-like constructors (sort of).
llvm-svn: 365973
types.
It seems some people like to write types that can explicitly convert
to anything, but cannot be used to explicitly construct anything.
This patch makes tuple tolerate such types, as is required
by the standard.
llvm-svn: 365074
The new meta-programming primitives are lower cost than the old versions. This patch removes those old versions and switches libc++ to use the new ones.
llvm-svn: 364160
When applied to a typedef or alias template, the [[nodebug]] attribute
makes the typedef transparent to the debugger, so instead of seeing
`std::__function::__alloc_func<remove_reference<void(&)()>::type,
allocator<remove_reference<void(&)()>, void()>::_Target` you see
`void(&)()` as the type of the variable in your debugger.
Removing all this SFINAE noise from debug info has huge binary size
wins, in addition to improving the readability.
For now this change is on by default. Users can override it by
specifying -D_LIBCPP_NODEBUG_TYPE=
llvm-svn: 363117
Summary:
This is not mandated by the Standard, but it's nonetheless a nice
property to have, especially since it's so easy to implement. It
also shrinks our bug list!
PR41714
Reviewers: mclow.lists, EricWF
Subscribers: christof, jkorous, dexonsmith, libcxx-commits
Tags: #libc
Differential Revision: https://reviews.llvm.org/D62618
llvm-svn: 363075
When the arguments to tuple cat were const, the const was incorrectly
propagated into the type of the resulting tuple. For example:
const std::tuple<int> t(42);
auto r = std::tuple_cat(t, t);
// Incorrect! should be std::tuple<int, int>.
static_assert(is_same_v<decltype(r), std::tuple<const int, const int>>);
llvm-svn: 359255
to reflect the new license.
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: 351636
Summary:
This was voted into C++20 in San Diego. Note that there was a revision
D0318R2 which did include unwrap_reference_t, but we mistakingly voted
P0318R1 into the C++20 Working Draft (which does not include
unwrap_reference_t). This patch implements D0318R2, which is what
we'll end up with in the Working Draft once this mistake has been
fixed.
Reviewers: EricWF, mclow.lists
Subscribers: christof, dexonsmith, libcxx-commits
Differential Revision: https://reviews.llvm.org/D54485
llvm-svn: 348138
Summary:
See https://bugs.llvm.org/show_bug.cgi?id=20855
Libc++ goes out of it's way to diagnose `std::tuple` constructions which are UB due to lifetime bugs caused by reference creation. For example:
```
// The 'const std::string&' is created *inside* the tuple constructor, and its lifetime is over before the end of the constructor call.
std::tuple<int, const std::string&> t(std::make_tuple(42, "abc"));
```
However, we are over-aggressive and we incorrectly diagnose cases such as:
```
void foo(std::tuple<int const&, int const&> const&);
foo(std::make_tuple(42, 42));
```
This patch fixes the incorrectly diagnosed cases, as well as converting the diagnostic to use the newly added Clang trait `__reference_binds_to_temporary`. The new trait allows us to diagnose cases we previously couldn't such as:
```
std::tuple<int, const std::string&> t(42, "abc");
```
Reviewers: rsmith, mclow.lists
Reviewed By: rsmith
Subscribers: cfe-commits
Differential Revision: https://reviews.llvm.org/D41977
llvm-svn: 323380
In addition to the PR for LWG 2773 this patch also ensures
that each of std::ignores constructors or assignment operators
are constexpr.
llvm-svn: 294165
MSVC/clang-cl doesn't do a full EBO unless __declspec(empty_bases)
is applied to the derived type. This causes certain tuple tests
to fail.
This patch adds the empty_bases attribute to __tuple_impl in order
for tuple to fully provide the EBO.
llvm-svn: 292159
The name _LIBCPP_TYPE_VIS_ONLY is no longer accurate because both
_LIBCPP_TYPE_VIS and _LIBCPP_TYPE_VIS_ONLY expand to
__attribute__((__type_visibility__)) with Clang. The only remaining difference
is that _LIBCPP_TYPE_VIS_ONLY can be applied to templates whereas
_LIBCPP_TYPE_VIS cannot (due to dllimport/dllexport not being allowed on
templates).
This patch renames _LIBCPP_TYPE_VIS_ONLY to _LIBCPP_TEMPLATE_VIS.
llvm-svn: 291035
This patch implements the correct PR for LWG 2770. It also makes the primary
tuple_size template incomplete again which fixes part of llvm.org/PR31513.
llvm-svn: 290846
This patch reverts the changes to tuple which fixed construction from
types derived from tuple. It breaks the code mentioned in llvm.org/PR31384.
I'll follow this commit up with a test case.
llvm-svn: 289773
Summary:
The standard requires tuple have the following constructors:
```
tuple(tuple<OtherTypes...> const&);
tuple(tuple<OtherTypes...> &&);
tuple(pair<T1, T2> const&);
tuple(pair<T1, T2> &&);
tuple(array<T, N> const&);
tuple(array<T, N> &&);
```
However libc++ implements these as a single constructor with the signature:
```
template <class TupleLike, enable_if_t<__is_tuple_like<TupleLike>::value>>
tuple(TupleLike&&);
```
This causes the constructor to reject types derived from tuple-like types; Unlike if we had all of the concrete overloads, because they cause the derived->base conversion in the signature.
This patch fixes this issue by detecting derived types and the tuple-like base they are derived from. It does this by creating an overloaded function with signatures for each of tuple/pair/array and checking if the possibly derived type can convert to any of them.
This patch fixes [PR17550]( https://llvm.org/bugs/show_bug.cgi?id=17550)
This patch
Reviewers: mclow.lists, K-ballo, mpark, EricWF
Subscribers: cfe-commits
Differential Revision: https://reviews.llvm.org/D27606
llvm-svn: 289727
This patch removes libc++'s tuple extension which allowed it to be
constructed from fewer initializers than elements; with the remaining
elements being default constructed. However the implicit version of
this extension breaks conforming code. For example:
int fun(std::string);
int fun(std::tuple<std::string, int>);
int x = fun("hello"); // ambigious
Because existing code may already depend on this extension it can be re-enabled
by defining _LIBCPP_ENABLE_TUPLE_IMPLICIT_REDUCED_ARITY_EXTENSION.
Note that the explicit version of this extension is still supported,
although it's somewhat less useful than the implicit one.
llvm-svn: 289158
Louis Dionne