Per P2493R0 and SD6, `__cpp_constexpr` of value `202002L` indicates that
P1330R0 "Changing the active member of a union inside constexpr" is
implemented, which is true for Clang 9 and later.
This flag has been deprecated since Clang 19, having been the default
since then.
It has remained because its negation was still useful to work around
backwards compatibility breaking changes from P0522.
However, in Clang 20 we have landed various changes which implemented
P3310R2 and beyond, which solve almost all of the expected issues, the
known remaining few being a bit obscure.
So this change removes the flag completely and all of its implementation
and support code.
Hopefully any remaining users can just stop using the flag. If there are
still important issues remaining, this removal will also shake the tree
and help us know.
Added a new `-Wpre-c++26-compat` warning for when this feature is used
in C++26 and a `-Wc++26-extensions` warning for when this is used in
C++11 through C++23.
---------
Co-authored-by: cor3ntin <corentinjabot@gmail.com>
Following the discussion on #101448 this defines
`__cpp_pack_indexing`. Since pack indexing is currently
supported in all language modes, the feature test macro
is also defined in all language modes.
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.
This is another try of https://reviews.llvm.org/D112921.
The original commit cf5a8b4 was reverted by 2e5035a due to some
failures (see #83774).
Fixes#60061
This patch will finally allow us to mark C++17 support in clang as
complete.
In order to implement this as a DR and avoid breaking reasonable code
that worked before P0522, this patch implements a provisional resolution
for CWG2398: When deducing template template parameters against each other,
and the argument side names a template specialization, instead of just
deducing A, we deduce a synthesized template template parameter based
on A, but with it's parameters using the template specialization's arguments
as defaults.
The driver flag is deprecated with a warning.
Fixes https://github.com/llvm/llvm-project/issues/36505
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.
This is another try of https://reviews.llvm.org/D112921.
Fixes#60061
After discussion with a few others, and seeing the state of our concepts
support, I believe it is worth trying to see if we can update this for
Clang19. The forcing function is that libstdc++'s `<expected>` header is
guarded by this macro, so we need to update it to support that.
* Set `__cpp_auto_cast`, as per
https://github.com/cplusplus/CWG/issues/281
* Support `__has_extension(cxx_generalized_nttp)` in C++20 as the
feature isn't stable enough for a feature test macro
* Support `__has_extension(cxx_explicit_this_parameter)` in c++23 as the
feature isn't stable enough for a feature test macro
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
This is a C++ feature that allows the use of `_` to
declare multiple variable of that name in the same scope;
these variables can then not be referred to.
In addition, while P2169 does not extend to parameter
declarations, we stop warning on unused parameters of that name,
for consistency.
The feature is backported to all C++ language modes.
Reviewed By: #clang-language-wg, aaron.ballman
Differential Revision: https://reviews.llvm.org/D153536
During the ISO C++ Committee meeting plenary session the C++23 Standard
has been voted as technical complete.
This updates the reference to c++2b to c++23 and updates the __cplusplus
macro.
Drive-by fixes c++1z -> c++17 and c++2a -> c++20 when seen.
Reviewed By: aaron.ballman
Differential Revision: https://reviews.llvm.org/D149553
The feature macro '__cpp_coroutines' is for coroutines TS. And the
coroutines TS is deprecated. So we should remove the feature macro too.
BTW, the corresponding feature macro for standard c++ coroutines is
'__cpp_impl_coroutine'.
Since we decided to remove the support for `-fcoroutines-ts` in
clang/llvm17 and the clang16/llvm16 is branched. So we're going to
remove the `-fcoroutines-ts` option.
This commit relands the patches for implementing P0960R3 and P1975R0,
which describe initializing aggregates via a parenthesized list.
The relanded commits are:
* 40c52159d3ee - P0960R3 and P1975R0: Allow initializing aggregates from
a parenthesized list of values
* c77a91bb7ba7 - Remove overly restrictive aggregate paren init logic
* 32d7aae04fdb - Fix a clang crash on invalid code in C++20 mode
This patch also fixes a crash in the original implementation.
Previously, if the input tried to call an implicitly deleted copy or
move constructor of a union, we would then try to initialize the union
by initializing it's first element with a reference to a union. This
behavior is incorrect (we should fail to initialize) and if the type of
the first element has a constructor with a single template typename
parameter, then Clang will explode. This patch fixes that issue by
checking that constructor overload resolution did not result in a
deleted function before attempting parenthesized aggregate
initialization.
Additionally, this patch also includes D140159, which contains some
minor fixes made in response to code review comments in the original
implementation that were made after that patch was submitted.
Co-authored-by: Sheng <ox59616e@gmail.com>
Fixes#54040, Fixes#59675
Reviewed By: ilya-biryukov
Differential Revision: https://reviews.llvm.org/D141546
This feature causes clang to crash when compiling Chrome - see
https://crbug.com/1405031 and
https://github.com/llvm/llvm-project/issues/59675
Revert "[clang] Fix a clang crash on invalid code in C++20 mode."
This reverts commit 32d7aae04fdb58e65a952f281ff2f2c3f396d98f.
Revert "[clang] Remove overly restrictive aggregate paren init logic"
This reverts commit c77a91bb7ba793ec3a6a5da3743ed55056291658.
Revert "[clang][C++20] P0960R3 and P1975R0: Allow initializing aggregates from a parenthesized list of values"
This reverts commit 40c52159d3ee337dbed14e4c73b5616ea354c337.
This patch implements P0960R3, which allows initialization of aggregates
via parentheses.
As an example:
```
struct S { int i, j; };
S s1(1, 1);
int arr1[2](1, 2);
```
This patch also implements P1975R0, which fixes the wording of P0960R3
for single-argument parenthesized lists so that statements like the
following are allowed:
```
S s2(1);
S s3 = static_cast<S>(1);
S s4 = (S)1;
int (&&arr2)[] = static_cast<int[]>(1);
int (&&arr3)[2] = static_cast<int[2]>(1);
```
This patch was originally authored by @0x59616e and completed by
@ayzhao.
Fixes#54040, Fixes#54041
Co-authored-by: Sheng <ox59616e@gmail.com>
Full write up : https://discourse.llvm.org/t/c-20-rfc-suggestion-desired-regarding-the-implementation-of-p0960r3/63744
Reviewed By: ilya-biryukov
Differential Revision: https://reviews.llvm.org/D129531
After accepted in Kona, update the code to accept static operator[] as well.
No big code changes: accept this operator as static in SemaDeclCXX, update AST call generation in SemaOverload and update feature macros + tests accordingly.
Reviewed By: cor3ntin, erichkeane, #clang-language-wg
Differential Revision: https://reviews.llvm.org/D138387
This implement the C++23 paper P2647R1 (adopted in Kona)
Reviewed By: #clang-language-wg, erichkeane
Differential Revision: https://reviews.llvm.org/D138851
Implement P2513
This change allows initializing an array of unsigned char,
or char from u8 string literals.
This was done both to support legacy code and for compatibility
with C where char8_t will be typedef to unsigned char.
This is backported to C++20 as per WG21 guidance.
Reviewed By: aaron.ballman
Differential Revision: https://reviews.llvm.org/D136449
Define the feature test macro for named character escapes.
I assume this was not done because it was implemented before formally accepted, right? cxx_status says the paper is implemented.
Reviewed By: cor3ntin
Differential Revision: https://reviews.llvm.org/D134898
Allow goto, labelled statements as well as `static`, `thread_local`, and
non-literal variables in `constexpr` functions.
As specified. for all of the above (except labelled statements) constant
evaluation of the construct still fails.
For `constexpr` bodies, the proposal is implemented with diagnostics as
a language extension in older language modes. For determination of
whether a lambda body satisfies the requirements for a constexpr
function, the proposal is implemented only in C++2b mode to retain the
semantics of older modes for programs conforming to them.
Reviewed By: aaron.ballman, hubert.reinterpretcast, erichkeane
Differential Revision: https://reviews.llvm.org/D111400
Now in libcxx and clang, all the coroutine components are defined in
std::experimental namespace.
And now the coroutine TS is merged into C++20. So in the working draft
like N4892, we could find the coroutine components is defined in std
namespace instead of std::experimental namespace.
And the coroutine support in clang seems to be relatively stable. So I
think it may be suitable to move the coroutine component into the
experiment namespace now.
This patch would make clang lookup coroutine_traits in std namespace
first. For the compatibility consideration, clang would lookup in
std::experimental namespace if it can't find definitions in std
namespace. So the existing codes wouldn't be break after update
compiler.
And in case the compiler found std::coroutine_traits and
std::experimental::coroutine_traits at the same time, it would emit an
error for it.
The support for looking up std::experimental::coroutine_traits would be
removed in Clang16.
Reviewed By: lxfind, Quuxplusone
Differential Revision: https://reviews.llvm.org/D108696
This reverts commit 2d7fba5f95f0614f6f2c4a4ed966b307d617898b.
The patch was reverted because it caused regression with rocThrust
due to ambiguity of template specialization.
For details please see https://reviews.llvm.org/D109496
A resolution to the ambiguity issues created by P0522, which is a DR solving
CWG 150, did not come as expected, so we are just going to accept the change,
and watch how users digest it.
For now we deprecate the flag with a warning, and make it on by default.
We don't remove the flag completely in order to give users a chance to
work around any problems by disabling it.
Signed-off-by: Matheus Izvekov <mizvekov@gmail.com>
Reviewed By: rsmith
Differential Revision: https://reviews.llvm.org/D109496
The feature was implemented in D99005, but we forgot to add the test
macro.
Reviewed By: Quuxplusone
Differential Revision: https://reviews.llvm.org/D104984
This completes the series implementing p1099, by adding the feature
macro and updating the web page.
Differential Revision: https://reviews.llvm.org/D102242
Some of the parts of this work were reverted; stop defining the feature
test macro for now.
This reverts commit b4c63ef6dd90dba9af26a111c9a78b121c5284b1.
Now with concepts support merged and mostly complete, we do not need -fconcepts-ts
(which was also misleading as we were not implementing the TS) and can enable
concepts features under C++2a. A warning will be generated if users still attempt
to use -fconcepts-ts.
