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===========================================
Clang |release| |ReleaseNotesTitle|
===========================================
.. contents::
:local:
:depth: 2
Written by the `LLVM Team <https://llvm.org/>`_
.. only:: PreRelease
.. warning::
These are in-progress notes for the upcoming Clang |version| release.
Release notes for previous releases can be found on
`the Releases Page <https://llvm.org/releases/>`_.
Introduction
============
This document contains the release notes for the Clang C/C++/Objective-C
frontend, part of the LLVM Compiler Infrastructure, release |release|. Here we
describe the status of Clang in some detail, including major
improvements from the previous release and new feature work. For the
general LLVM release notes, see `the LLVM
documentation <https://llvm.org/docs/ReleaseNotes.html>`_. For the libc++ release notes,
see `this page <https://libcxx.llvm.org/ReleaseNotes.html>`_. All LLVM releases
may be downloaded from the `LLVM releases web site <https://llvm.org/releases/>`_.
For more information about Clang or LLVM, including information about the
latest release, please see the `Clang Web Site <https://clang.llvm.org>`_ or the
`LLVM Web Site <https://llvm.org>`_.
Potentially Breaking Changes
============================
These changes are ones which we think may surprise users when upgrading to
Clang |release| because of the opportunity they pose for disruption to existing
code bases.
- Setting the deprecated CMake variable ``GCC_INSTALL_PREFIX`` (which sets the
default ``--gcc-toolchain=``) now leads to a fatal error.
C/C++ Language Potentially Breaking Changes
-------------------------------------------
C++ Specific Potentially Breaking Changes
-----------------------------------------
- Clang now diagnoses function/variable templates that shadow their own template parameters, e.g. ``template<class T> void T();``.
This error can be disabled via `-Wno-strict-primary-template-shadow` for compatibility with previous versions of clang.
ABI Changes in This Version
---------------------------
- Fixed Microsoft name mangling of implicitly defined variables used for thread
safe static initialization of static local variables. This change resolves
incompatibilities with code compiled by MSVC but might introduce
incompatibilities with code compiled by earlier versions of Clang when an
inline member function that contains a static local variable with a dynamic
initializer is declared with ``__declspec(dllimport)``. (#GH83616).
- Fixed Microsoft name mangling of lifetime extended temporary objects. This
change corrects missing back reference registrations that could result in
incorrect back reference indexes and suprising demangled name results. Since
MSVC uses a different mangling for these objects, compatibility is not affected.
(#GH85423).
AST Dumping Potentially Breaking Changes
----------------------------------------
Clang Frontend Potentially Breaking Changes
-------------------------------------------
- Removed support for constructing on-stack ``TemplateArgumentList``s; interfaces should instead
use ``ArrayRef<TemplateArgument>`` to pass template arguments. Transitioning internal uses to
``ArrayRef<TemplateArgument>`` reduces AST memory usage by 0.4% when compiling clang, and is
expected to show similar improvements on other workloads.
- The ``-Wgnu-binary-literal`` diagnostic group no longer controls any
diagnostics. Binary literals are no longer a GNU extension, they're now a C23
extension which is controlled via ``-pedantic`` or ``-Wc23-extensions``. Use
of ``-Wno-gnu-binary-literal`` will no longer silence this pedantic warning,
which may break existing uses with ``-Werror``.
What's New in Clang |release|?
==============================
Some of the major new features and improvements to Clang are listed
here. Generic improvements to Clang as a whole or to its underlying
infrastructure are described first, followed by language-specific
sections with improvements to Clang's support for those languages.
C++ Language Changes
--------------------
C++20 Feature Support
^^^^^^^^^^^^^^^^^^^^^
- Clang won't perform ODR checks for decls in the global module fragment any
more to ease the implementation and improve the user's using experience.
This follows the MSVC's behavior. Users interested in testing the more strict
behavior can use the flag '-Xclang -fno-skip-odr-check-in-gmf'.
(#GH79240).
- Implemented the `__is_layout_compatible` intrinsic to support
`P0466R5: Layout-compatibility and Pointer-interconvertibility Traits <https://wg21.link/P0466R5>`_.
- Clang now implements [module.import]p7 fully. Clang now will import module
units transitively for the module units coming from the same module of the
current module units.
Fixes `#84002 <https://github.com/llvm/llvm-project/issues/84002>`_.
- Initial support for class template argument deduction (CTAD) for type alias
templates (`P1814R0 <https://wg21.link/p1814r0>`_).
(#GH54051).
C++23 Feature Support
^^^^^^^^^^^^^^^^^^^^^
- Implemented `P2718R0: Lifetime extension in range-based for loops <https://wg21.link/P2718R0>`_. Also
materialize temporary object which is a prvalue in discarded-value expression.
- Implemented `P1774R8: Portable assumptions <https://wg21.link/P1774R8>`_.
- Implemented `P2448R2: Relaxing some constexpr restrictions <https://wg21.link/P2448R2>`_.
C++2c Feature Support
^^^^^^^^^^^^^^^^^^^^^
- Implemented `P2662R3 Pack Indexing <https://wg21.link/P2662R3>`_.
Resolutions to C++ Defect Reports
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[Sema] Substitute parameter packs when deduced from function arguments (#79371) This pull request would solve https://github.com/llvm/llvm-project/issues/78449 . There is also a discussion about this on stackoverflow: https://stackoverflow.com/questions/77832658/stdtype-identity-to-support-several-variadic-argument-lists . The following program is well formed: ```cpp #include <type_traits> template <typename... T> struct args_tag { using type = std::common_type_t<T...>; }; template <typename... T> void bar(args_tag<T...>, std::type_identity_t<T>..., int, std::type_identity_t<T>...) {} // example int main() { bar(args_tag<int, int>{}, 4, 8, 15, 16, 23); } ``` but Clang rejects it, while GCC and MSVC doesn't. The reason for this is that, in `Sema::DeduceTemplateArguments` we are not prepared for this case. # Substitution/deduction of parameter packs The logic that handles substitution when we have explicit template arguments (`SubstituteExplicitTemplateArguments`) does not work here, since the types of the pack are not pushed to `ParamTypes` before the loop starts that does the deduction. The other "candidate" that may could have handle this case would be the loop that does the deduction for trailing packs, but we are not dealing with trailing packs here. # Solution proposed in this PR The solution proposed in this PR works similar to the trailing pack deduction. The main difference here is the end of the deduction cycle. When a non-trailing template pack argument is found, whose type is not explicitly specified and the next type is not a pack type, the length of the previously deduced pack is retrieved (let that length be `s`). After that the next `s` arguments are processed in the same way as in the case of non trailing packs. # Another possible solution There is another possible approach that would be less efficient. In the loop when we get to an element of `ParamTypes` that is a pack and could be substituted because the type is deduced from a previous argument, then `s` number of arg types would be inserted before the current element of `ParamTypes` type. Then we would "cancel" the processing of the current element, first process the previously inserted elements and the after that re-process the current element. Basically we would do what `SubstituteExplicitTemplateArguments` does but during deduction. # Adjusted test cases In `clang/test/CXX/temp/temp.fct.spec/temp.deduct/temp.deduct.call/p1-0x.cpp` there is a test case named `test_pack_not_at_end` that should work, but still does not. This test case is relevant because the note for the error message has changed. This is what the test case looks like currently: ```cpp template<typename ...Types> void pack_not_at_end(tuple<Types...>, Types... values, int); // expected-note {{<int *, double *> vs. <int, int>}} void test_pack_not_at_end(tuple<int*, double*> t2) { pack_not_at_end(t2, 0, 0, 0); // expected-error {{no match}} // FIXME: Should the "original argument type must match deduced parameter // type" rule apply here? pack_not_at_end<int*, double*>(t2, 0, 0, 0); // ok } ``` The previous note said (before my changes): ``` deduced conflicting types for parameter 'Types' (<int *, double *> vs. <>) ```` The current note says (after my changesand also clang 14 would say this if the pack was not trailing): ``` deduced conflicting types for parameter 'Types' (<int *, double *> vs. <int, int>) ``` GCC says: ``` error: no matching function for call to ‘pack_not_at_end(std::tuple<int*, double*>&, int, int, int)’ 70 | pack_not_at_end(t2, 0, 0, 9); // expected-error {{no match}} ```` --------- Co-authored-by: cor3ntin <corentinjabot@gmail.com> Co-authored-by: Erich Keane <ekeane@nvidia.com>
2024-01-27 10:43:38 +01:00
- Substitute template parameter pack, when it is not explicitly specified
in the template parameters, but is deduced from a previous argument.
(`#78449: <https://github.com/llvm/llvm-project/issues/78449>`_).
- Type qualifications are now ignored when evaluating layout compatibility
of two types.
(`CWG1719: Layout compatibility and cv-qualification revisited <https://cplusplus.github.io/CWG/issues/1719.html>`_).
- Alignment of members is now respected when evaluating layout compatibility
of structs.
(`CWG2583: Common initial sequence should consider over-alignment <https://cplusplus.github.io/CWG/issues/2583.html>`_).
- ``[[no_unique_address]]`` is now respected when evaluating layout
compatibility of two types.
(`CWG2759: [[no_unique_address] and common initial sequence <https://cplusplus.github.io/CWG/issues/2759.html>`_).
C Language Changes
------------------
C23 Feature Support
^^^^^^^^^^^^^^^^^^^
- No longer diagnose use of binary literals as an extension in C23 mode. Fixes
#GH72017.
- Corrected parsing behavior for the ``alignas`` specifier/qualifier in C23. We
previously handled it as an attribute as in C++, but there are parsing
differences. The behavioral differences are:
.. code-block:: c
struct alignas(8) /* was accepted, now rejected */ S {
char alignas(8) /* was rejected, now accepted */ C;
};
int i alignas(8) /* was accepted, now rejected */ ;
Fixes (#GH81472).
- Clang now generates predefined macros of the form ``__TYPE_FMTB__`` and
``__TYPE_FMTb__`` (e.g., ``__UINT_FAST64_FMTB__``) in C23 mode for use with
macros typically exposed from ``<inttypes.h>``, such as ``PRIb8``.
(`#81896: <https://github.com/llvm/llvm-project/issues/81896>`_).
- Clang now supports `N3018 The constexpr specifier for object definitions`
<https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3018.htm>`_.
Non-comprehensive list of changes in this release
-------------------------------------------------
- Added ``__builtin_readsteadycounter`` for reading fixed frequency hardware
counters.
- ``__builtin_addc``, ``__builtin_subc``, and the other sizes of those
builtins are now constexpr and may be used in constant expressions.
- Added ``__builtin_popcountg`` as a type-generic alternative to
``__builtin_popcount{,l,ll}`` with support for any unsigned integer type. Like
the previous builtins, this new builtin is constexpr and may be used in
constant expressions.
- Lambda expressions are now accepted in C++03 mode as an extension.
New Compiler Flags
------------------
- ``-Wmissing-designated-field-initializers``, grouped under ``-Wmissing-field-initializers``.
This diagnostic can be disabled to make ``-Wmissing-field-initializers`` behave
like it did before Clang 18.x. Fixes (`#56628 <https://github.com/llvm/llvm-project/issues/68933>`_)
Deprecated Compiler Flags
-------------------------
Modified Compiler Flags
-----------------------
- Added a new diagnostic flag ``-Wreturn-mismatch`` which is grouped under
``-Wreturn-type``, and moved some of the diagnostics previously controlled by
``-Wreturn-type`` under this new flag. Fixes #GH72116.
- Added ``-Wcast-function-type-mismatch`` under the ``-Wcast-function-type``
warning group. Moved the diagnostic previously controlled by
``-Wcast-function-type`` to the new warning group and added
``-Wcast-function-type-mismatch`` to ``-Wextra``. #GH76872
.. code-block:: c
int x(long);
typedef int (f2)(void*);
typedef int (f3)();
void func(void) {
// Diagnoses under -Wcast-function-type, -Wcast-function-type-mismatch,
// -Wcast-function-type-strict, -Wextra
f2 *b = (f2 *)x;
// Diagnoses under -Wcast-function-type, -Wcast-function-type-strict
f3 *c = (f3 *)x;
}
Removed Compiler Flags
-------------------------
- The ``-freroll-loops`` flag has been removed. It had no effect since Clang 13.
- ``-m[no-]unaligned-access`` is removed for RISC-V and LoongArch.
``-m[no-]strict-align``, also supported by GCC, should be used instead.
(`#85350 <https://github.com/llvm/llvm-project/pull/85350>`_.)
Attribute Changes in Clang
--------------------------
- Introduced a new function attribute ``__attribute__((amdgpu_max_num_work_groups(x, y, z)))`` or
``[[clang::amdgpu_max_num_work_groups(x, y, z)]]`` for the AMDGPU target. This attribute can be
attached to HIP or OpenCL kernel function definitions to provide an optimization hint. The parameters
``x``, ``y``, and ``z`` specify the maximum number of workgroups for the respective dimensions,
and each must be a positive integer when provided. The parameter ``x`` is required, while ``y`` and
``z`` are optional with default value of 1.
- The ``swiftasynccc`` attribute is now considered to be a Clang extension
rather than a language standard feature. Please use
``__has_extension(swiftasynccc)`` to check the availability of this attribute
for the target platform instead of ``__has_feature(swiftasynccc)``. Also,
added a new extension query ``__has_extension(swiftcc)`` corresponding to the
``__attribute__((swiftcc))`` attribute.
Improvements to Clang's diagnostics
-----------------------------------
- Clang now applies syntax highlighting to the code snippets it
prints.
- Clang now diagnoses member template declarations with multiple declarators.
- Clang now diagnoses use of the ``template`` keyword after declarative nested
name specifiers.
- The ``-Wshorten-64-to-32`` diagnostic is now grouped under ``-Wimplicit-int-conversion`` instead
of ``-Wconversion``. Fixes #GH69444.
- Clang now uses thousand separators when printing large numbers in integer overflow diagnostics.
Fixes #GH80939.
- Clang now diagnoses friend declarations with an ``enum`` elaborated-type-specifier in language modes after C++98.
- Added diagnostics for C11 keywords being incompatible with language standards
before C11, under a new warning group: ``-Wpre-c11-compat``.
- Now diagnoses an enumeration constant whose value is larger than can be
represented by ``unsigned long long``, which can happen with a large constant
using the ``wb`` or ``uwb`` suffix. The maximal underlying type is currently
``unsigned long long``, but this behavior may change in the future when Clang
implements
`WG14 N3029 <https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3029.htm>`_.
(#GH69352).
- Clang now diagnoses extraneous template parameter lists as a language extension.
- Clang now diagnoses declarative nested name specifiers that name alias templates.
- Clang now diagnoses lambda function expressions being implicitly cast to boolean values, under ``-Wpointer-bool-conversion``.
Fixes #GH82512.
- Clang now provides improved warnings for the ``cleanup`` attribute to detect misuse scenarios,
such as attempting to call ``free`` on an unallocated object. Fixes
`#79443 <https://github.com/llvm/llvm-project/issues/79443>`_.
- Clang no longer warns when the ``bitand`` operator is used with boolean
operands, distinguishing it from potential typographical errors or unintended
bitwise operations. Fixes #GH77601.
- Clang now correctly diagnoses no arguments to a variadic macro parameter as a C23/C++20 extension.
Fixes #GH84495.
Improvements to Clang's time-trace
----------------------------------
Bug Fixes in This Version
-------------------------
- Fixed missing warnings when comparing mismatched enumeration constants
in C (`#29217 <https://github.com/llvm/llvm-project/issues/29217>`).
- Clang now accepts elaborated-type-specifiers that explicitly specialize
a member class template for an implicit instantiation of a class template.
- Fixed missing warnings when doing bool-like conversions in C23 (#GH79435).
- Clang's ``-Wshadow`` no longer warns when an init-capture is named the same as
a class field unless the lambda can capture this.
Fixes (#GH71976)
- Clang now accepts qualified partial/explicit specializations of variable templates that
are not nominable in the lookup context of the specialization.
- Clang now doesn't produce false-positive warning `-Wconstant-logical-operand`
for logical operators in C23.
Fixes (#GH64356).
- ``__is_trivially_relocatable`` no longer returns ``false`` for volatile-qualified types.
Fixes (#GH77091).
- Clang no longer produces a false-positive `-Wunused-variable` warning
for variables created through copy initialization having side-effects in C++17 and later.
Fixes (#GH64356) (#GH79518).
- Fix value of predefined macro ``__FUNCTION__`` in MSVC compatibility mode.
Fixes (#GH66114).
- Clang now emits errors for explicit specializations/instatiations of lambda call
operator.
Fixes (#GH83267).
- Clang now correctly generates overloads for bit-precise integer types for
builtin operators in C++. Fixes #GH82998.
[Clang] [Sema] Fix bug in `_Complex float`+`int` arithmetic (#83063) C23 6.3.1.8 ‘Usual arithmetic conversions’ p1 states (emphasis mine): > Otherwise, if the corresponding real type of either operand is `float`, the other operand is converted, *without change of type domain*, to a type whose corresponding real type is `float`. ‘type domain’ here refers to `_Complex` vs real (i.e. non-`_Complex`); there is another clause that states the same for `double`. Consider the following code: ```c++ _Complex float f; int x; f / x; ``` After talking this over with @AaronBallman, we came to the conclusion that `x` should be converted to `float` and *not* `_Complex float` (that is, we should perform a division of `_Complex float / float`, and *not* `_Complex float / _Complex float`; the same also applies to `-+*`). This was already being done correctly for cases where `x` was already a `float`; it’s just mixed `_Complex float`+`int` operations that currently suffer from this problem. This pr removes the extra `FloatingRealToComplex` conversion that we were erroneously inserting and adds some tests to make sure we’re actually doing `_Complex float / float` and not `_Complex float / _Complex float` (and analogously for `double` and `-+*`). The only exception here is `float / _Complex float`, which calls a library function (`__divsc3`) that takes 4 `float`s, so we end up having to convert the `float` to a `_Complex float` after all (and analogously for `double`); I don’t believe there is a way around this. Lastly, we were also missing tests for `_Complex` arithmetic at compile time, so this adds some tests for that as well.
2024-03-13 17:39:23 +01:00
- When performing mixed arithmetic between ``_Complex`` floating-point types and integers,
Clang now correctly promotes the integer to its corresponding real floating-point
type only rather than to the complex type (e.g. ``_Complex float / int`` is now evaluated
as ``_Complex float / float`` rather than ``_Complex float / _Complex float``), as mandated
by the C standard. This significantly improves codegen of `*` and `/` especially.
Fixes (`#31205 <https://github.com/llvm/llvm-project/issues/31205>`_).
- Fixes an assertion failure on invalid code when trying to define member
functions in lambdas.
Bug Fixes to Compiler Builtins
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Bug Fixes to Attribute Support
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Bug Fixes to C++ Support
^^^^^^^^^^^^^^^^^^^^^^^^
- Fix crash when calling the constructor of an invalid class.
(#GH10518) (#GH67914) (#GH78388)
- Fix crash when using lifetimebound attribute in function with trailing return.
(#GH73619)
- Addressed an issue where constraints involving injected class types are perceived
distinct from its specialization types. (#GH56482)
- Fixed a bug where variables referenced by requires-clauses inside
nested generic lambdas were not properly injected into the constraint scope. (#GH73418)
- Fixed a crash where substituting into a requires-expression that refers to function
parameters during the equivalence determination of two constraint expressions.
(#GH74447)
- Fixed deducing auto& from const int in template parameters of partial
specializations. (#GH77189)
- Fix for crash when using a erroneous type in a return statement.
(#GH63244) (#GH79745)
[clang][Sema] Populate function template depth at AddTemplateOverloadCandidate (#80395) This is yet another one-line patch to fix crashes on constraint substitution. ```cpp template <class, class> struct formatter; template <class, class> struct basic_format_context {}; template <typename CharType> concept has_format_function = format(basic_format_context<CharType, CharType>()); template <typename ValueType, typename CharType> requires has_format_function<CharType> struct formatter<ValueType, CharType> { template <typename OutputIt> CharType format(basic_format_context<OutputIt, CharType>); }; ``` In this case, we would build up a `RecoveryExpr` for a call within a constraint expression due to the absence of viable functions. The heuristic algorithm attempted to find such a function inside of a ClassTemplatePartialSpecialization, from which we started to substitute its requires-expression, and it succeeded with a FunctionTemplate such that 1) It has only one parameter, which is dependent. 2) The only one parameter depends on two template parameters. They are, in canonical form, `<template-parameter-1-0>` and `<template-parameter-0-1>` respectively. Before we emit an error, we still want to recover the most viable functions. This goes downhill to deducing template parameters against its arguments, where we would collect the argument type with the same depth as the parameter type into a Deduced set. The size of the set is presumed to be that of function template parameters, which is 1 in this case. However, since we haven't yet properly set the template depth before the dance, we'll end up putting the type for `<template-parameter-0-1>` to the second position of Deduced set, which is unfortunately an access violation! The bug seems to appear since clang 12.0. This fixes [the case](https://github.com/llvm/llvm-project/issues/58548#issuecomment-1287935336).
2024-02-03 16:14:48 +08:00
- Fixed an out-of-bounds error caused by building a recovery expression for ill-formed
function calls while substituting into constraints. (#GH58548)
- Fix incorrect code generation caused by the object argument
of ``static operator()`` and ``static operator[]`` calls not being evaluated. (#GH67976)
- Fix crash and diagnostic with const qualified member operator new.
Fixes (#GH79748)
- Fixed a crash where substituting into a requires-expression that involves parameter packs
during the equivalence determination of two constraint expressions. (#GH72557)
- Fix a crash when specializing an out-of-line member function with a default
parameter where we did an incorrect specialization of the initialization of
the default parameter. (#GH68490)
- Fix a crash when trying to call a varargs function that also has an explicit object parameter.
Fixes (#GH80971)
- Reject explicit object parameters on `new` and `delete` operators. (#GH82249)
- Fix a crash when trying to call a varargs function that also has an explicit object parameter. (#GH80971)
- Fixed a bug where abbreviated function templates would append their invented template parameters to
an empty template parameter lists.
- Fix parsing of abominable function types inside type traits.
Fixes (`#77585 <https://github.com/llvm/llvm-project/issues/77585>`_)
- Clang now classifies aggregate initialization in C++17 and newer as constant
or non-constant more accurately. Previously, only a subset of the initializer
elements were considered, misclassifying some initializers as constant. Partially fixes
#GH80510.
- Clang now ignores top-level cv-qualifiers on function parameters in template partial orderings. (#GH75404)
- No longer reject valid use of the ``_Alignas`` specifier when declaring a
local variable, which is supported as a C11 extension in C++. Previously, it
was only accepted at namespace scope but not at local function scope.
- Clang no longer tries to call consteval constructors at runtime when they appear in a member initializer. (#GH82154)
- Fix crash when using an immediate-escalated function at global scope. (#GH82258)
- Correctly immediate-escalate lambda conversion functions. (#GH82258)
- Fixed an issue where template parameters of a nested abbreviated generic lambda within
a requires-clause lie at the same depth as those of the surrounding lambda. This,
in turn, results in the wrong template argument substitution during constraint checking.
(#GH78524)
[Clang][Sema] Defer instantiation of exception specification until after partial ordering when determining primary template (#82417) Consider the following: ``` struct A { static constexpr bool x = true; }; template<typename T, typename U> void f(T, U) noexcept(T::y); // #1, error: no member named 'y' in 'A' template<typename T, typename U> void f(T, U*) noexcept(T::x); // #2 template<> void f(A, int*) noexcept; // explicit specialization of #2 ``` We currently instantiate the exception specification of all candidate function template specializations when deducting template arguments for an explicit specialization, which results in a error despite `#1` not being selected by partial ordering as the most specialized template. According to [except.spec] p13: > An exception specification is considered to be needed when: > - [...] > - the exception specification is compared to that of another declaration (e.g., an explicit specialization or an overriding virtual function); Assuming that "comparing declarations" means "determining whether the declarations correspond and declare the same entity" (per [basic.scope.scope] p4 and [basic.link] p11.1, respectively), the exception specification does _not_ need to be instantiated until _after_ partial ordering, at which point we determine whether the implicitly instantiated specialization and the explicit specialization declare the same entity (the determination of whether two functions/function templates correspond does not consider the exception specifications). This patch defers the instantiation of the exception specification until a single function template specialization is selected via partial ordering, matching the behavior of GCC, EDG, and MSVC: see https://godbolt.org/z/Ebb6GTcWE.
2024-02-26 09:58:55 -05:00
- Clang no longer instantiates the exception specification of discarded candidate function
templates when determining the primary template of an explicit specialization.
- Fixed a crash in Microsoft compatibility mode where unqualified dependent base class
lookup searches the bases of an incomplete class.
[Clang] [Sema] Handle placeholders in '.*' expressions (#83103) When analysing whether we should handle a binary expression as an overloaded operator call or a builtin operator, we were calling `checkPlaceholderForOverload()`, which takes care of any placeholders that are not overload sets—which would usually make sense since those need to be handled as part of overload resolution. Unfortunately, we were also doing that for `.*`, which is not overloadable, and then proceeding to create a builtin operator anyway, which would crash if the RHS happened to be an unresolved overload set (due hitting an assertion in `CreateBuiltinBinOp()`—specifically, in one of its callees—in the `.*` case that makes sure its arguments aren’t placeholders). This pr instead makes it so we check for *all* placeholders early if the operator is `.*`. It’s worth noting that, 1. In the `.*` case, we now additionally also check for *any* placeholders (not just non-overload-sets) in the LHS; this shouldn’t make a difference, however—at least I couldn’t think of a way to trigger the assertion with an overload set as the LHS of `.*`; it is worth noting that the assertion in question would also complain if the LHS happened to be of placeholder type, though. 2. There is another case in which we also don’t perform overload resolution—namely `=` if the LHS is not of class or enumeration type after handling non-overload-set placeholders—as in the `.*` case, but similarly to 1., I first couldn’t think of a way of getting this case to crash, and secondly, `CreateBuiltinBinOp()` doesn’t seem to care about placeholders in the LHS or RHS in the `=` case (from what I can tell, it, or rather one of its callees, only checks that the LHS is not a pseudo-object type, but those will have already been handled by the call to `checkPlaceholderForOverload()` by the time we get to this function), so I don’t think this case suffers from the same problem. This fixes #53815. --------- Co-authored-by: Aaron Ballman <aaron@aaronballman.com>
2024-02-27 20:19:44 +01:00
- Fix a crash when an unresolved overload set is encountered on the RHS of a ``.*`` operator.
(#GH53815)
- In ``__restrict``-qualified member functions, attach ``__restrict`` to the pointer type of
``this`` rather than the pointee type.
Fixes (#GH82941), (#GH42411) and (#GH18121).
- Clang now properly reports supported C++11 attributes when using
``__has_cpp_attribute`` and parses attributes with arguments in C++03 (#GH82995)
- Clang now properly diagnoses missing 'default' template arguments on a variety
of templates. Previously we were diagnosing on any non-function template
instead of only on class, alias, and variable templates, as last updated by
CWG2032. Fixes (#GH83461)
- Fixed an issue where an attribute on a declarator would cause the attribute to
be destructed prematurely. This fixes a pair of Chromium that were brought to
our attention by an attempt to fix in (#GH77703). Fixes (#GH83385).
- Fix evaluation of some immediate calls in default arguments.
Fixes (#GH80630)
- Fixed an issue where the ``RequiresExprBody`` was involved in the lambda dependency
calculation. (#GH56556), (#GH82849).
- Fix a bug where overload resolution falsely reported an ambiguity when it was comparing
a member-function against a non member function or a member-function with an
explicit object parameter against a member function with no explicit object parameter
when one of the function had more specialized templates.
Fixes (`#82509 <https://github.com/llvm/llvm-project/issues/82509>`_)
and (`#74494 <https://github.com/llvm/llvm-project/issues/74494>`_)
- Allow access to a public template alias declaration that refers to friend's
private nested type. (#GH25708).
- Fixed a crash in constant evaluation when trying to access a
captured ``this`` pointer in a lambda with an explicit object parameter.
Fixes (#GH80997)
- Fix an issue where missing set friend declaration in template class instantiation.
Fixes (#GH84368).
- Fixed a crash while checking constraints of a trailing requires-expression of a lambda, that the
expression references to an entity declared outside of the lambda. (#GH64808)
- Clang's __builtin_bit_cast will now produce a constant value for records with empty bases. See:
(#GH82383)
- Fix a crash when instantiating a lambda that captures ``this`` outside of its context. Fixes (#GH85343).
- Fix an issue where a namespace alias could be defined using a qualified name (all name components
following the first `::` were ignored).
Bug Fixes to AST Handling
^^^^^^^^^^^^^^^^^^^^^^^^^
- Clang now properly preserves ``FoundDecls`` within a ``ConceptReference``. (#GH82628)
Miscellaneous Bug Fixes
^^^^^^^^^^^^^^^^^^^^^^^
Miscellaneous Clang Crashes Fixed
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
- Do not attempt to dump the layout of dependent types or invalid declarations
when ``-fdump-record-layouts-complete`` is passed.
Fixes (`#83684 <https://github.com/llvm/llvm-project/issues/83684>`_).
OpenACC Specific Changes
------------------------
Target Specific Changes
-----------------------
AMDGPU Support
^^^^^^^^^^^^^^
X86 Support
^^^^^^^^^^^
Arm and AArch64 Support
^^^^^^^^^^^^^^^^^^^^^^^
- ARMv7+ targets now default to allowing unaligned access, except Armv6-M, and
Armv8-M without the Main Extension. Baremetal targets should check that the
new default will work with their system configurations, since it requires
that SCTLR.A is 0, SCTLR.U is 1, and that the memory in question is
configured as "normal" memory. This brings Clang in-line with the default
settings for GCC and Arm Compiler. Aside from making Clang align with other
compilers, changing the default brings major performance and code size
improvements for most targets. We have not changed the default behavior for
ARMv6, but may revisit that decision in the future. Users can restore the old
behavior with -m[no-]unaligned-access.
- An alias identifier (rdma) has been added for targeting the AArch64
Architecture Extension which uses Rounding Doubling Multiply Accumulate
instructions (rdm). The identifier is available on the command line as
a feature modifier for -march and -mcpu as well as via target attributes
like ``target_version`` or ``target_clones``.
- Support has been added for the following processors (-mcpu identifiers in parenthesis):
* Arm Cortex-A78AE (cortex-a78ae).
* Arm Cortex-A520AE (cortex-a520ae).
* Arm Cortex-A720AE (cortex-a720ae).
Android Support
^^^^^^^^^^^^^^^
Windows Support
^^^^^^^^^^^^^^^
[clang] [MinGW] Add the option -fno-auto-import In GCC, the .refptr stubs are only generated for x86_64, and only for code models medium and larger (and medium is the default for x86_64 since this was introduced). They can be omitted for projects that are conscious about performance and size, and don't need automatically importing dll data members, by passing -mcmodel=small. In Clang/LLVM, such .refptr stubs are generated for any potentially symbol reference that might end up autoimported. The .refptr stubs are emitted for three separate reasons: - Without .refptr stubs, undefined symbols are mostly referenced with 32 bit wide relocations. If the symbol ends up autoimported from a different DLL, a 32 bit relative offset might not be enough to reference data in a different DLL, depending on runtime loader layout. - Without .refptr stubs, the runtime pseudo relocation mechanism will need to temporarily make sections read-write-executable if there are such relocations in the text section - On ARM and AArch64, the immediate addressing encoded into instructions isn't in the form of a plain 32 bit relative offset, but is expressed with various bits scattered throughout two instructions - the mingw runtime pseudo relocation mechanism doesn't support updating offsets in that form. If autoimporting is known not to be needed, the user can now compile with -fno-auto-import, avoiding the extra overhead of the .refptr stubs. However, omitting them is potentially fragile as the code might still rely on automatically importing some symbol without the developer knowing. If this happens, linking still usually will succeed, but users may encounter issues at runtime. Therefore, if the new option -fno-auto-import is passed to the compiler when driving linking, it passes the flag --disable-auto-import to the linker, making sure that no symbols actually are autoimported when the generated code doesn't expect it. Differential Revision: https://reviews.llvm.org/D61670
2019-05-08 11:45:26 +03:00
[clang] Add `intrin0.h` header to mimic `intrin0.h` used by MSVC STL for clang-cl (#75711) Fixes https://github.com/llvm/llvm-project/issues/53520. #### Description #### Provide `intrin0.h` to be the minimal set of intrinsics that the MSVC STL requires. The `intrin0.h` header matches the latest header provided by MSVC 1939 which does include some extra intrinsics that the MSVC STL does not use. Inside `BuiltinHeaders.def` I kept the header description as `intrin.h`. If you want me to change those to `intrin0.h` for the moved intrinsics let me know. This should now allow `immintrin.h` to be used with function targets for runtime cpu detection of simd instruction sets without worrying about the compile-time overhead from MSVC STL including `intrin.h` on clang. I still need to figure out how to best update MSVC STL to detect for the presence of `intrin0.h` from clang and to use this header over `intrin.h`. #### Testing #### Built clang locally and ran the test suite. I still need to do a pass over the existing unit tests for the ms intrinsics to make sure there aren't any gaps. Wanted to get this PR up for discussion first. Modified latest MSVC STL from github to point to `intrin0.h` for clang. Wrote some test files that included MSVC STL headers that rely on intrinsics such as `atomic`, `bit` and `vector`. Built the unit tests against x86, arm, aarch64, and x64. #### Benchmarks #### The following include times are based on the x64 target with the modified headers in this PR. These timings were done by using `clang-cl.exe -ftime-trace` and taking the wall time for parsing `intrin.h` and `intrin0.h`. `intrin.h` takes ~897ms to parse. `intrin0.h` takes ~1ms to parse. If there is anything required or a different approach is preferred let me know. I would very much like to move this over the finish line so we can use function targets with clang-cl.
2024-03-19 08:30:54 -04:00
- Clang-cl now supports function targets with intrinsic headers. This allows
for runtime feature detection of intrinsics. Previously under clang-cl
``immintrin.h`` and similar intrinsic headers would only include the intrinsics
if building with that feature enabled at compile time, e.g. ``avxintrin.h``
would only be included if AVX was enabled at compile time. This was done to work
around include times from MSVC STL including ``intrin.h`` under clang-cl.
Clang-cl now provides ``intrin0.h`` for MSVC STL and therefore all intrinsic
features without requiring enablement at compile time.
Fixes: (`#53520 <https://github.com/llvm/llvm-project/issues/53520>`_)
- Improved compile times with MSVC STL. MSVC provides ``intrin0.h`` which is a
header that only includes intrinsics that are used by MSVC STL to avoid the
use of ``intrin.h``. MSVC STL when compiled under clang uses ``intrin.h``
instead. Clang-cl now provides ``intrin0.h`` for the same compiler throughput
purposes as MSVC. Clang-cl also provides ``yvals_core.h`` to redefine
``_STL_INTRIN_HEADER`` to expand to ``intrin0.h`` instead of ``intrin.h``.
This also means that if all intrinsic features are enabled at compile time
including STL headers will no longer slow down compile times since ``intrin.h``
is not included from MSVC STL.
LoongArch Support
^^^^^^^^^^^^^^^^^
RISC-V Support
^^^^^^^^^^^^^^
- ``__attribute__((rvv_vector_bits(N)))`` is now supported for RVV vbool*_t types.
- Profile names in ``-march`` option are now supported.
CUDA/HIP Language Changes
^^^^^^^^^^^^^^^^^^^^^^^^^
- PTX is no longer included by default when compiling for CUDA. Using
``--cuda-include-ptx=all`` will return the old behavior.
CUDA Support
^^^^^^^^^^^^
AIX Support
^^^^^^^^^^^
WebAssembly Support
^^^^^^^^^^^^^^^^^^^
AVR Support
^^^^^^^^^^^
DWARF Support in Clang
----------------------
Floating Point Support in Clang
-------------------------------
Fixed Point Support in Clang
----------------------------
- Support fixed point precision macros according to ``7.18a.3`` of
`ISO/IEC TR 18037:2008 <https://standards.iso.org/ittf/PubliclyAvailableStandards/c051126_ISO_IEC_TR_18037_2008.zip>`_.
AST Matchers
------------
- ``isInStdNamespace`` now supports Decl declared with ``extern "C++"``.
- Add ``isExplicitObjectMemberFunction``.
- Fixed ``forEachArgumentWithParam`` and ``forEachArgumentWithParamType`` to
not skip the explicit object parameter for operator calls.
clang-format
------------
- ``AlwaysBreakTemplateDeclarations`` is deprecated and renamed to
``BreakTemplateDeclarations``.
- ``AlwaysBreakAfterReturnType`` is deprecated and renamed to
``BreakAfterReturnType``.
libclang
--------
Static Analyzer
---------------
- Fixed crashing on loops if the loop variable was declared in switch blocks
but not under any case blocks if ``unroll-loops=true`` analyzer config is
set. (#GH68819)
- Support C++23 static operator calls. (#GH84972)
New features
^^^^^^^^^^^^
Crash and bug fixes
^^^^^^^^^^^^^^^^^^^
Improvements
^^^^^^^^^^^^
- Support importing C++20 modules in clang-repl.
- Added support for ``TypeLoc::dump()`` for easier debugging, and improved
textual and JSON dumping for various ``TypeLoc``-related nodes.
Moved checkers
^^^^^^^^^^^^^^
.. _release-notes-sanitizers:
Sanitizers
----------
- ``-fsanitize=signed-integer-overflow`` now instruments signed arithmetic even
when ``-fwrapv`` is enabled. Previously, only division checks were enabled.
Users with ``-fwrapv`` as well as a sanitizer group like
``-fsanitize=undefined`` or ``-fsanitize=integer`` enabled may want to
manually disable potentially noisy signed integer overflow checks with
``-fno-sanitize=signed-integer-overflow``
Python Binding Changes
----------------------
- Exposed `CXRewriter` API as `class Rewriter`.
- Add some missing kinds from Index.h (CursorKind: 149-156, 272-320, 420-437.
TemplateArgumentKind: 5-9. TypeKind: 161-175 and 178).
OpenMP Support
--------------
- Added support for the `[[omp::assume]]` attribute.
Additional Information
======================
A wide variety of additional information is available on the `Clang web
page <https://clang.llvm.org/>`_. The web page contains versions of the
2020-03-22 22:18:40 +01:00
API documentation which are up-to-date with the Git version of
the source code. You can access versions of these documents specific to
this release by going into the "``clang/docs/``" directory in the Clang
tree.
If you have any questions or comments about Clang, please feel free to
contact us on the `Discourse forums (Clang Frontend category)
<https://discourse.llvm.org/c/clang/6>`_.