diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -13,7 +13,7 @@ .. warning:: These are in-progress notes for the upcoming Clang |version| release. Release notes for previous releases can be found on - `the Download Page `_. + `the Releases Page `_. Introduction ============ @@ -23,43 +23,32 @@ 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 `_. All LLVM -releases may be downloaded from the `LLVM releases web -site `_. +documentation `_. For the libc++ release notes, +see `this page `_. All LLVM releases +may be downloaded from the `LLVM releases web site `_. For more information about Clang or LLVM, including information about the latest release, please see the `Clang Web Site `_ or the `LLVM Web Site `_. -Note that if you are reading this file from a Git checkout or the -main Clang web page, this document applies to the *next* release, not -the current one. To see the release notes for a specific release, please -see the `releases page `_. - 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. -- Clang will now correctly diagnose as ill-formed a constant expression where an - enum without a fixed underlying type is set to a value outside the range of - the enumeration's values. - - .. code-block:: c++ +- Clang's default C++/ObjC++ standard is now ``gnu++17`` instead of ``gnu++14``. + This means Clang will by default accept code using features from C++17 and + conforming GNU extensions. Projects incompatible with C++17 can add + ``-std=gnu++14`` to their build settings to restore the previous behaviour. - enum E { Zero, One, Two, Three, Four }; - constexpr E Val1 = (E)3; // Ok - constexpr E Val2 = (E)7; // Ok - constexpr E Val3 = (E)8; // Now diagnosed as out of the range [0, 7] - constexpr E Val4 = (E)-1; // Now diagnosed as out of the range [0, 7] +- The ``-fexperimental-new-pass-manager`` and ``-fno-legacy-pass-manager`` + flags have been removed. These flags have been silently ignored since Clang 15. - Due to the extended period of time this bug was present in major C++ - implementations (including Clang), this error has the ability to be - downgraded into a warning (via: ``-Wno-error=enum-constexpr-conversion``) to - provide a transition period for users. This diagnostic is expected to turn - into an error-only diagnostic in the next Clang release. Fixes - `Issue 50055 `_. +- Clang's resource directory path previously included the full clang version. + It now includes only the major version. The new resource directory is + ``$prefix/lib/clang/$CLANG_MAJOR_VERSION`` and can be queried using + ``clang -print-resource-dir``, just like before. - The ``-Wimplicit-function-declaration`` and ``-Wimplicit-int`` warnings now default to an error in C99, C11, and C17. As of C2x, @@ -89,17 +78,26 @@ void (*fp)(int *) = func; // Previously a warning, now a downgradable error. } +- To match GCC, ``__ppc64__`` is no longer defined on PowerPC64 targets. Use + ``__powerpc64__`` instead. + +- ``-p`` is rejected for all targets which are not AIX or OpenBSD. ``-p`` led + to an ``-Wunused-command-line-argument`` warning in previous releases. + +C/C++ Language Potentially Breaking Changes +------------------------------------------- + - Clang now disallows types whose sizes aren't a multiple of their alignments to be used as the element type of arrays. .. code-block:: c - typedef char int8_a16 __attribute__((aligned(16))); - int8_a16 array[4]; // Now diagnosed as the element size not being a multiple of the array alignment. + typedef char int8_a16 __attribute__((aligned(16))); + int8_a16 array[4]; // Now diagnosed as the element size not being a multiple of the array alignment. - When compiling for Windows in MSVC compatibility mode (for example by using clang-cl), the compiler will now propagate dllimport/export declspecs in - explicit specializations of class template member functions (`Issue 54717 + explicit specializations of class template member functions (`#54717 `_): .. code-block:: c++ @@ -143,8 +141,8 @@ - Clang now diagnoses use of a bit-field as an instruction operand in Microsoft style inline asm blocks as an error. Previously, a bit-field operand yielded the address of the allocation unit the bit-field was stored within; reads or - writes therefore had the potential to read or write nearby bit-fields. This - change fixes `issue 57791 `_. + writes therefore had the potential to read or write nearby bit-fields. + (`#57791 `_) .. code-block:: c++ @@ -158,8 +156,35 @@ } } -- The ``-fexperimental-new-pass-manager`` and ``-fno-legacy-pass-manager`` - flags have been removed. These have been no-ops since 15.0.0. +- Clang now diagnoses if structs/unions with the same name are different in + different used modules. Behavior in C and Objective-C language modes now is + the same as in C++. + +C++ Specific Potentially Breaking Changes +----------------------------------------- +- Clang now prohibits non-inline externally-visible definitions in C++ + standard header units as per ``[module.import/6]``. In Clang 15, + these definitions were allowed. Note that such definitions are ODR + violations if the header is included more than once. + +- Clang will now correctly diagnose as ill-formed a constant expression where an + enum without a fixed underlying type is set to a value outside the range of + the enumeration's values. + + .. code-block:: c++ + + enum E { Zero, One, Two, Three, Four }; + constexpr E Val1 = (E)3; // Ok + constexpr E Val2 = (E)7; // Ok + constexpr E Val3 = (E)8; // Now diagnosed as out of the range [0, 7] + constexpr E Val4 = (E)-1; // Now diagnosed as out of the range [0, 7] + + Due to the extended period of time this bug was present in major C++ + implementations (including Clang), this error has the ability to be + downgraded into a warning (via: ``-Wno-error=enum-constexpr-conversion``) to + provide a transition period for users. This diagnostic is expected to turn + into an error-only diagnostic in the next Clang release. + (`#50055 `_) - As a side effect of implementing DR692/DR1395/DR1432, Clang now rejects some overloaded function templates as ambiguous when one of the candidates has a @@ -176,25 +201,18 @@ g(42); } -- Clang's resource dir used to include the full clang version. It will now - include only the major version. The new resource directory is - ``$prefix/lib/clang/$CLANG_MAJOR_VERSION`` and can be queried using - ``clang -print-resource-dir``, just like before. - -- To match GCC, ``__ppc64__`` is no longer defined on PowerPC64 targets. Use - ``__powerpc64__`` instead. - -- ``-p`` is rejected for all targets which are not AIX or OpenBSD. ``-p`` led - to an ``-Wunused-command-line-argument`` warning in previous releases. - -- Clang now diagnoses non-inline externally-visible definitions in C++ - standard header units as per ``[module.import/6]``. Previously, in Clang-15, - these definitions were allowed. Note that such definitions are ODR - violations if the header is included more than once. - -- Clang now diagnoses if structs/unions with the same name are different in - different used modules. Behavior in C and Objective-C language modes now is - the same as in C++. +ABI Changes in This Version +--------------------------- +- GCC doesn't pack non-POD members in packed structs unless the packed + attribute is also specified on the member. Clang historically did perform + such packing. Clang now matches the gcc behavior + (except on Darwin, PS4 and AIX). + You can switch back to the old ABI behavior with the flag: + ``-fclang-abi-compat=15.0``. +- GCC allows POD types to have defaulted special members. Clang historically + classified such types as non-POD (for the purposes of Itanium ABI). Clang now + matches the gcc behavior (except on Darwin, PS4, AIX and z/OS). You can switch + back to the old ABI behavior with the flag: ``-fclang-abi-compat=15.0``. What's New in Clang |release|? ============================== @@ -203,324 +221,234 @@ infrastructure are described first, followed by language-specific sections with improvements to Clang's support for those languages. -Major New Features +C++ Language Changes +-------------------- + +C++20 Feature Support +^^^^^^^^^^^^^^^^^^^^^ + +Newly implemented papers: + +- Implemented `P0848: Conditionally Trivial Special Member Functions `_. + Note: The handling of deleted functions is not yet compliant, as Clang + does not implement `DR1496 `_ + and `DR1734 `_. + +- Implemented `P1091R3 `_ and `P1381R1 `_ to + support capturing structured bindings in lambdas (`#52720 `_, + `#54300 `_, + `#54301 `_, + `#49430 `_). + +- Implemented `P2468R2: The Equality Operator You Are Looking For `_. + +- Implemented `P2113R0: Proposed resolution for 2019 comment CA 112 `_ + ([temp.func.order]p6.2.1 is not implemented, matching GCC). + +- Implemented `P0634R3: Down with typename! `_, + which removes the requirement for the ``typename`` keyword in certain contexts. + +- Implemented `P0857R0: Fixing small-ish functionality gaps in constraints `_, + which specifies constrained lambdas and constrained template *template-parameter*\s. + +- Implemented `P0960R3 `_ + and `P1975R0 `_, + which allow parenthesized aggregate-initialization. + +Notable Bug Fixes to C++20 Features: + +- Clang now correctly delays the instantiation of function constraints until + the time of checking, which should now allow the libstdc++ ranges implementation + to work for at least trivial examples. + (`#44178 `_) + +- Consider explicitly defaulted constexpr/consteval special member function + template instantiation to be constexpr/consteval even though a call to such + a function cannot appear in a constant expression. + (C++14 [dcl.constexpr]p6 (CWG DR647/CWG DR1358)) + +- Correctly defer dependent immediate function invocations until template instantiation. + (`#55601 `_) + +- Correctly set expression evaluation context as 'immediate function context' in + consteval functions. + (`#51182 `_) + +- Skip rebuilding lambda expressions in arguments of immediate invocations. + (`#56183 `_, + `#51695 `_, + `#50455 `_, + `#54872 `_, + `#54587 `_) + +- Clang implements DR2621, correcting a defect in ``using enum`` handling. The + name is found via ordinary lookup so typedefs are found. + +- Implemented CWG2635 as a Defect Report, which prohibits structured bindings from being constrained. + +- When using header modules, inclusion of a private header and violations of + the `use-declaration rules + `_ are now + diagnosed even when the includer is a textual header. This change can be + temporarily reversed with ``-Xclang + -fno-modules-validate-textual-header-includes``, but this flag will be + removed in a future Clang release. + +C++2b Feature Support +^^^^^^^^^^^^^^^^^^^^^ +- Implemented `P2324R2: Support label at end of compound statement `_. +- Implemented `P1169R4: static operator() `_ and `P2589R1: static operator[] `_. +- Implemented `P2513R3: char8_t Compatibility and Portability Fix `_. + This change was applied to C++20 as a Defect Report. +- Implemented `P2647R1: Permitting static constexpr variables in constexpr functions `_. +- Implemented `CWG2640: Allow more characters in an n-char sequence `_. + +Resolutions to C++ Defect Reports +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +- Implemented `DR692 `_, `DR1395 `_, + and `DR1432 `_. The fix for DR1432 is speculative since the + issue is still open and has no proposed resolution at this time. A speculative fix + for DR1432 is needed to prevent regressions that would otherwise occur due to DR692. +- Implemented `DR2358 `_, which allows init captures in lambdas in default arguments. +- Implemented `DR2654 `_ which undeprecates + all compound assignments operations on volatile qualified variables. +- Implemented `DR2631 `_. Invalid ``consteval`` calls in default arguments and default + member initializers are diagnosed when and if the default is used. + This changes the value of ``std::source_location::current()`` + used in default parameters calls compared to previous versions of Clang. + (`#56379 `_) + +C Language Changes ------------------ +- Adjusted ``-Wformat`` warnings according to `WG14 N2562 `_. + Clang will now consider default argument promotions in ``printf``, and remove + unnecessary warnings. Especially ``int`` argument with specifier ``%hhd`` and + ``%hd``. -Bug Fixes ---------- -- ``stdatomic.h`` will use the internal declarations when targeting pre-C++-23 - on Windows platforms as the MSVC support requires newer C++ standard. -- Correct ``_Static_assert`` to accept the same set of extended integer - constant expressions as is accpted in other contexts that accept them. - This fixes `Issue 57687 `_. -- Fixes an accepts-invalid bug in C when using a ``_Noreturn`` function - specifier on something other than a function declaration. This fixes - `Issue 56800 `_. -- Fix `#56772 `_ - invalid - destructor names were incorrectly accepted on template classes. -- Improve compile-times with large dynamic array allocations with trivial - constructors. This fixes - `Issue 56774 `_. -- No longer assert/miscompile when trying to make a vectorized ``_BitInt`` type - using the ``ext_vector_type`` attribute (the ``vector_size`` attribute was - already properly diagnosing this case). -- Fix clang not properly diagnosing the failing subexpression when chained - binary operators are used in a ``static_assert`` expression. -- Fix a crash when evaluating a multi-dimensional array's array filler - expression is element-dependent. This fixes - `Issue 50601 `_. -- Fixed a crash-on-valid with consteval evaluation of a list-initialized - constructor for a temporary object. This fixes - `Issue 55871 `_. -- Fix `#57008 `_ - Builtin - C++ language extension type traits instantiated by a template with unexpected - number of arguments cause an assertion fault. -- Fix multi-level pack expansion of undeclared function parameters. - This fixes `Issue 56094 `_. -- Fix `#57151 `_. - ``-Wcomma`` is emitted for void returning functions. -- ``-Wtautological-compare`` missed warnings for tautological comparisons - involving a negative integer literal. This fixes - `Issue 42918 `_. -- Fix a crash when generating code coverage information for an - ``if consteval`` statement. This fixes - `Issue 57377 `_. -- Fix assert that triggers a crash during template name lookup when a type was - incomplete but was not also a TagType. This fixes - `Issue 57387 `_. -- Fix a crash when emitting a concept-related diagnostic. This fixes - `Issue 57415 `_. -- Fix a crash when attempting to default a virtual constexpr non-special member - function in a derived class. This fixes - `Issue 57431 `_ -- Fix a crash where we attempt to define a deleted destructor. This fixes - `Issue 57516 `_ -- Fix ``__builtin_assume_aligned`` crash when the 1st arg is array type. This fixes - `Issue 57169 `_ -- Clang configuration files are now read through the virtual file system - rather than the physical one, if these are different. -- Clang will now no longer treat a C 'overloadable' function without a prototype as - a variadic function with the attribute. This should make further diagnostics more - clear. -- Fixes to builtin template emulation of regular templates. - `Issue 42102 `_ - `Issue 51928 `_ -- A SubstTemplateTypeParmType can now represent the pack index for a - substitution from an expanded pack. - `Issue 56099 `_ -- Fix `-Wpre-c++17-compat` crashing Clang when compiling C++20 code which - contains deduced template specializations. This Fixes - `Issue 57369 `_ - `Issue 57643 `_ - `Issue 57793 `_ -- Respect constructor constraints during class template argument deduction (CTAD). - This is the suggested resolution to CWG DR2628. - `Issue 57646 `_ - `Issue 43829 `_ -- Fixed a crash in C++20 mode in Clang and Clangd when compile source - with compilation errors. - `Issue 53628 `_ -- The template arguments of a variable template being accessed as a - member will now be represented in the AST. -- Fix incorrect handling of inline builtins with asm labels. -- Finished implementing C++ DR2565, which results in a requirement becoming - not satisfied in the event of an instantiation failures in a requires expression's - parameter list. We previously handled this correctly in a constraint evaluation - context, but not in a requires clause evaluated as a boolean. -- Address the thread identification problems in coroutines. - `Issue 47177 `_ - `Issue 47179 `_ -- Fix a crash upon stray coloncolon token in C2x mode. -- Reject non-type template arguments formed by casting a non-zero integer - to a pointer in pre-C++17 modes, instead of treating them as null - pointers. -- Fix template arguments of pointer and reference not taking the type as - part of their identity. - `Issue 47136 `_ -- Fix a crash when trying to form a recovery expression on a call inside a - constraint, which re-evaluated the same constraint. - `Issue 53213 `_ - `Issue 45736 `_ -- Fix an issue when performing constraints partial ordering on non-template - functions. `Issue 56154 `_ -- Fix handling of unexpanded packs in template argument expressions. - `Issue 58679 `_ -- Fix a crash when a ``btf_type_tag`` attribute is applied to the pointee of - a function pointer. -- Fix a number of recursively-instantiated constraint issues, which would possibly - result in a stack overflow. - `Issue 44304 `_ - `Issue 50891 `_ -- Clang 14 predeclared some builtin POSIX library functions in ``gnu2x`` mode, - and Clang 15 accidentally stopped predeclaring those functions in that - language mode. Clang 16 now predeclares those functions again. This fixes - `Issue 56607 `_. -- GNU attributes being applied prior to standard attributes would be handled - improperly, which was corrected to match the behaviour exhibited by GCC. - `Issue 58229 `_ -- The builtin type trait ``__is_aggregate`` now returns ``true`` for arrays of incomplete - types in accordance with the suggested fix for `LWG3823 `_ -- Fix bug with using enum that could lead to enumerators being treated as if - they were part of an overload set. This fixes - `Issue 58067 `_ - `Issue 59014 `_ - `Issue 54746 `_ -- Fix assert that triggers a crash during some types of list initialization that - generate a CXXTemporaryObjectExpr instead of a InitListExpr. This fixes - `Issue 58302 `_ - `Issue 58753 `_ - `Issue 59100 `_ -- Fix issue using __attribute__((format)) on non-variadic functions that expect - more than one formatted argument. -- Fix bug where constant evaluation treated a pointer to member that points to - a weak member as never being null. Such comparisons are now treated as - non-constant. -- Fix sanity check when value initializing an empty union so that it takes into - account anonymous structs which is a GNU extension. This fixes - `Issue 58800 `_ -- Fix an issue that triggers a crash if we instantiate a hidden friend functions. - This fixes `Issue 54457 `_ -- Fix an issue where -frewrite-includes generated line control directives with - incorrect line numbers in some cases when a header file used an end of line - character sequence that differed from the primary source file. - `Issue 59736 `_ -- In C mode, when ``e1`` has ``__attribute__((noreturn))`` but ``e2`` doesn't, - ``(c ? e1 : e2)`` is no longer considered noreturn. - `Issue 59792 `_ -- Fix an issue that makes Clang crash on lambda template parameters. This fixes - `Issue 57960 `_ -- Fix issue that the standard C++ modules importer will call global - constructor/destructor for the global varaibles in the importing modules. - This fixes `Issue 59765 `_ -- Reject in-class defaulting of previosly declared comparison operators. Fixes - `Issue 51227 `_. -- Fix the bug of inserting the ``ZeroInitializationFixit`` before the template - argument list of ``VarTemplateSpecializationDecl``. +C2x Feature Support +^^^^^^^^^^^^^^^^^^^ +- Implemented `WG14 N2662 `_, + so the ``[[maybe_unused]]`` attribute may be applied to a label to silence an + ``-Wunused-label`` warning. +- Implemented `WG14 N2508 `_, + so labels can placed everywhere inside a compound statement. +- Implemented `WG14 N2927 `_, + the Not-so-magic ``typeof`` operator. Also implemented + `WG14 N2930 `_, + renaming ``remove_quals``, so the ``typeof_unqual`` operator is also + supported. Both of these operators are supported only in C2x mode. The + ``typeof`` operator specifies the type of the given parenthesized expression + operand or type name, including all qualifiers. The ``typeof_unqual`` + operator is similar to ``typeof`` except that all qualifiers are removed, + including atomic type qualification and type attributes which behave like a + qualifier, such as an address space attribute. -Improvements to Clang's diagnostics -^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ -- Disabled FIT-IT suggested for a case of bad conversion in system headers. -- Clang will now check compile-time determinable string literals as format strings. - Fixes `Issue 55805: `_. -- ``-Wformat`` now recognizes ``%b`` for the ``printf``/``scanf`` family of - functions and ``%B`` for the ``printf`` family of functions. Fixes - `Issue 56885: `_. -- Introduced ``-Wsingle-bit-bitfield-constant-conversion``, grouped under - ``-Wbitfield-constant-conversion``, which diagnoses implicit truncation when - ``1`` is assigned to a 1-bit signed integer bitfield. This fixes - `Issue 53253 `_. To reduce - potential false positives, this diagnostic will not diagnose use of the - ``true`` macro (from ``>`) in C language mode despite the macro - being defined to expand to ``1``. -- Clang will now print more information about failed static assertions. In - particular, simple static assertion expressions are evaluated to their - compile-time value and printed out if the assertion fails. -- Diagnostics about uninitialized ``constexpr`` varaibles have been improved - to mention the missing constant initializer. -- Correctly diagnose a future keyword if it exist as a keyword in the higher - language version and specifies in which version it will be a keyword. This - supports both c and c++ language. -- When diagnosing multi-level pack expansions of mismatched lengths, Clang will - now, in most cases, be able to point to the relevant outer parameter. -- ``no_sanitize("...")`` on a global variable for known but not relevant - sanitizers is now just a warning. It now says that this will be ignored - instead of incorrectly saying no_sanitize only applies to functions and - methods. -- No longer mention ``reinterpet_cast`` in the invalid constant expression - diagnostic note when in C mode. -- Clang will now give a more suitale diagnostic for declaration of block - scope identifiers that have external/internal linkage that has an initializer. - Fixes `Issue 57478: `_. -- New analysis pass will now help preserve sugar when combining deductions, in an - order agnostic way. This will be in effect when deducing template arguments, - when deducing function return type from multiple return statements, for the - conditional operator, and for most binary operations. Type sugar is combined - in a way that strips the sugar which is different between terms, and preserves - those which are common. -- Correctly diagnose use of an integer literal without a suffix whose - underlying type is ``long long`` or ``unsigned long long`` as an extension in - C89 mode . Clang previously only diagnosed if the literal had an explicit - ``LL`` suffix. -- Clang now correctly diagnoses index that refers past the last possible element - of FAM-like arrays. -- Clang now correctly diagnoses a warning when defercencing a void pointer in C mode. - This fixes `Issue 53631 `_ -- Clang will now diagnose an overload set where a candidate has a constraint that - refers to an expression with a previous error as nothing viable, so that it - doesn't generate strange cascading errors, particularly in cases where a - subsuming constraint fails, which would result in a less-specific overload to - be selected. -- Add a fix-it hint for the ``-Wdefaulted-function-deleted`` warning to - explicitly delete the function. -- Fixed an accidental duplicate diagnostic involving the declaration of a - function definition without a prototype which is preceded by a static - declaration of the function with a prototype. Fixes - `Issue 58181 `_. -- Copy-elided initialization of lock scopes is now handled differently in - ``-Wthread-safety-analysis``: annotations on the move constructor are no - longer taken into account, in favor of annotations on the function returning - the lock scope by value. This could result in new warnings if code depended - on the previous undocumented behavior. As a side effect of this change, - constructor calls outside of initializer expressions are no longer ignored, - which can result in new warnings (or make existing warnings disappear). -- The wording of diagnostics regarding arithmetic on fixed-sized arrays and - pointers is improved to include the type of the array and whether it's cast - to another type. This should improve comprehension for why an index is - out-of-bounds. -- Clang now correctly points to the problematic parameter for the ``-Wnonnull`` - warning. This fixes - `Issue 58273 `_. -- Introduced ``-Wcast-function-type-strict`` and - ``-Wincompatible-function-pointer-types-strict`` to warn about function type - mismatches in casts and assignments that may result in runtime indirect call - `Control-Flow Integrity (CFI) - `_ failures. The - ``-Wcast-function-type-strict`` diagnostic is grouped under - ``-Wcast-function-type`` as it identifies a more strict set of potentially - problematic function type casts. -- Clang will now disambiguate NTTP types when printing diagnostic that contain NTTP types. - Fixes `Issue 57562 `_. -- Better error recovery for pack expansion of expressions. - `Issue 58673 `_. -- Better diagnostics when the user has missed `auto` in a declaration. - `Issue 49129 `_. -- Clang now diagnoses use of invalid or reserved module names in a module - export declaration. Both are diagnosed as an error, but the diagnostic is - suppressed for use of reserved names in a system header. -- ``-Winteger-overflow`` will diagnose overflow in more cases. This fixes - `Issue 58944 `_. -- Clang has an internal limit of 2GB of preprocessed source code per - compilation, including source reachable through imported AST files such as - PCH or modules. When Clang hits this limit, it now produces notes mentioning - which header and source files are consuming large amounts of this space. - ``#pragma clang __debug sloc_usage`` can also be used to request this report. -- Clang no longer permits the keyword 'bool' in a concept declaration as a - concepts-ts compatibility extension. -- Clang now diagnoses overflow undefined behavior in a constant expression while - evaluating a compound assignment with remainder as operand. -- Add ``-Wreturn-local-addr``, a GCC alias for ``-Wreturn-stack-address``. -- Clang now suppresses ``-Wlogical-op-parentheses`` on ``(x && a || b)`` and ``(a || b && x)`` - only when ``x`` is a string literal. -- Clang will now reject the GNU extension address of label in coroutines explicitly. - This fixes `Issue 56436 `_. -- Clang now automatically adds ``[[clang::lifetimebound]]`` to the parameters of - ``std::move, std::forward`` et al, this enables Clang to diagnose more cases - where the returned reference outlives the object. + .. code-block:: c + + __attribute__((address_space(1))) const _Atomic int Val; + typeof(Val) OtherVal; // type is '__attribute__((address_space(1))) const _Atomic int' + typeof_unqual(Val) OtherValUnqual; // type is 'int' + +- Implemented `WG14 N3042 `_, + Introduce the nullptr constant. This introduces a new type ``nullptr_t``, + declared in ```` which represents the type of the null pointer named + constant, ``nullptr``. This constant is implicitly convertible to any pointer + type and represents a type-safe null value. + + Note, there are some known incompatibilities with this same feature in C++. + The following examples were discovered during implementation and are subject + to change depending on how national body comments are resolved by WG14 (C + status is based on standard requirements, not necessarily implementation + behavior): + + .. code-block:: c + + nullptr_t null_val; + (nullptr_t)nullptr; // Rejected in C, accepted in C++, Clang accepts + (void)(1 ? nullptr : 0); // Rejected in C, accepted in C++, Clang rejects + (void)(1 ? null_val : 0); // Rejected in C, accepted in C++, Clang rejects + bool b1 = nullptr; // Accepted in C, rejected in C++, Clang rejects + b1 = null_val; // Accepted in C, rejected in C++, Clang rejects + null_val = 0; // Rejected in C, accepted in C++, Clang rejects + + void func(nullptr_t); + func(0); // Rejected in C, accepted in C++, Clang rejects + +- Implemented `WG14 N2975 `_, + Relax requirements for va_start. In C2x mode, functions can now be declared + fully variadic and the ``va_start`` macro no longer requires passing a second + argument (though it accepts a second argument for backwards compatibility). + If a second argument is passed, it is neither expanded nor evaluated in C2x + mode. + + .. code-block:: c + + void func(...) { // Invalid in C17 and earlier, valid in C2x and later. + va_list list; + va_start(list); // Invalid in C17 and earlier, valid in C2x and later. + va_end(list); + } + +- Diagnose type definitions in the ``type`` argument of ``__builtin_offsetof`` + as a conforming C extension according to + `WG14 N2350 `_. + Also documents the builtin appropriately. Note, a type definition in C++ + continues to be rejected. Non-comprehensive list of changes in this release ------------------------------------------------- - It's now possible to set the crash diagnostics directory through the environment variable ``CLANG_CRASH_DIAGNOSTICS_DIR``. The ``-fcrash-diagnostics-dir`` flag takes precedence. -- When using header modules, inclusion of a private header and violations of - the `use-declaration rules - `_ are now - diagnosed even when the includer is a textual header. This change can be - temporarily reversed with ``-Xclang - -fno-modules-validate-textual-header-includes``, but this flag will be - removed in a future Clang release. + - Unicode support has been updated to support Unicode 15.0. New unicode codepoints are supported as appropriate in diagnostics, C and C++ identifiers, and escape sequences. + - In identifiers, Clang allows a restricted set of additional mathematical symbols as an extension. These symbols correspond to a proposed Unicode `Mathematical notation profile for default identifiers `_. - This resolves `Issue 54732 `_. + (`#54732 `_) + - Clang now supports loading multiple configuration files. The files from default configuration paths are loaded first, unless ``--no-default-config`` option is used. All files explicitly specified using ``--config=`` option are loaded afterwards. + - When loading default configuration files, clang now unconditionally uses the real target triple (respecting options such as ``--target=`` and ``-m32``) rather than the executable prefix. The respective configuration files are also loaded when clang is called via an executable without a prefix (e.g. plain ``clang``). + - Default configuration paths were partially changed. Clang now attempts to load ``-.cfg`` first, and falls back to loading both ``.cfg`` and ``.cfg`` if the former is not found. `Triple` is the target triple and `driver` first tries the canonical name for the driver (respecting ``--driver-mode=``), and then the name found in the executable. + - If the environment variable ``SOURCE_DATE_EPOCH`` is set, it specifies a UNIX timestamp to be used in replacement of the current date and time in the ``__DATE__``, ``__TIME__``, and ``__TIMESTAMP__`` macros. See ``_. + - Clang now supports ``__has_constexpr_builtin`` function-like macro that evaluates to 1 if the builtin is supported and can be constant evaluated. It can be used to writing conditionally constexpr code that uses builtins. + - The time profiler (using ``-ftime-trace`` option) now traces various constant evaluation events. + - Clang can now generate a PCH when using ``-fdelayed-template-parsing`` for code with templates containing loop hint pragmas, OpenMP pragmas, and ``#pragma unused``. -- Now diagnoses use of a member access expression or array subscript expression - within ``__builtin_offsetof`` and ``offsetof`` as being a Clang extension. New Compiler Flags ------------------ -- Implemented `-fcoro-aligned-allocation` flag. This flag implements +- Implemented ``-fcoro-aligned-allocation`` flag. This flag implements Option 2 of P2014R0 aligned allocation of coroutine frames (`P2014R0 `_). With this flag, the coroutines will try to lookup aligned allocation @@ -528,8 +456,8 @@ find aligned allocation function. So if the user code implemented self defined allocation function for coroutines, the existing code will be broken. A little divergence with P2014R0 is that clang will lookup - `::operator new(size_­t, std::aligned_val_t, nothrow_­t)` if there is - `get_­return_­object_­on_­allocation_­failure`. We feel this is more consistent + ``::operator new(size_­t, std::aligned_val_t, nothrow_­t)`` if there is + ``get_­return_­object_­on_­allocation_­failure``. We feel this is more consistent with the intention. - Added ``--no-default-config`` to disable automatically loading configuration @@ -588,10 +516,6 @@ - Clang now no longer supports ``-cc1 -fconcepts-ts``. This flag has been deprecated and encouraged use of ``-std=c++20`` since Clang 10, so we're now removing it. -New Pragmas in Clang --------------------- -- ... - Attribute Changes in Clang -------------------------- - Added support for ``__attribute__((guard(nocf)))`` and C++-style @@ -628,262 +552,392 @@ `_ for more details. -Windows Support ---------------- -- For the MinGW driver, added the options ``-mguard=none``, ``-mguard=cf`` and - ``-mguard=cf-nochecks`` (equivalent to ``/guard:cf-``, ``/guard:cf`` and - ``/guard:cf,nochecks`` in clang-cl) for enabling Control Flow Guard checks - and generation of address-taken function table. +Improvements to Clang's diagnostics +----------------------------------- +- Disabled a FIX-IT suggested for a case of bad conversion in system headers. -- Switched from SHA1 to BLAKE3 for PDB type hashing / ``-gcodeview-ghash`` +- Clang will now check compile-time determinable string literals as format strings. + (`#55805 `_) -- Fixed code generation with emulated TLS, when the emulated TLS is enabled - by default (with downstream patches; no upstream configurations default - to this configuration, but some mingw downstreams change the default - in this way). +- ``-Wformat`` now recognizes ``%b`` for the ``printf``/``scanf`` family of + functions and ``%B`` for the ``printf`` family of functions. + (`#56885 `_) -- Improved detection of MinGW cross sysroots for finding sysroots provided - by Linux distributions such as Fedora. Also improved such setups by - avoiding to include ``/usr/include`` among the include paths when cross - compiling with a cross sysroot based in ``/usr``. +- Introduced ``-Wsingle-bit-bitfield-constant-conversion``, grouped under + ``-Wbitfield-constant-conversion``, which diagnoses implicit truncation when + ``1`` is assigned to a 1-bit signed integer bitfield. To reduce + potential false positives, this diagnostic will not diagnose use of the + ``true`` macro (from ````) in C language mode despite the macro + being defined to expand to ``1``. (`#53253 `_) -AIX Support ------------ -* When using ``-shared``, the clang driver now invokes llvm-nm to create an - export list if the user doesn't specify one via linker flag or pass an - alternative export control option. +- Clang will now print more information about failed static assertions. In + particular, simple static assertion expressions are evaluated to their + compile-time value and printed out if the assertion fails. -C Language Changes in Clang ---------------------------- -- Adjusted ``-Wformat`` warnings according to `WG14 N2562 `_. - Clang will now consider default argument promotions in ``printf``, and remove - unnecessary warnings. Especially ``int`` argument with specifier ``%hhd`` and - ``%hd``. +- Diagnostics about uninitialized ``constexpr`` variables have been improved + to mention the missing constant initializer. + +- Correctly diagnose a future keyword if it exists as a keyword in the higher + language version and specifies in which version it will be a keyword. This + supports both C and C++. + +- When diagnosing multi-level pack expansions of mismatched lengths, Clang will + now, in most cases, be able to point to the relevant outer parameter. + +- ``no_sanitize("...")`` on a global variable for known but not relevant + sanitizers is now just a warning. It now says that this will be ignored + instead of incorrectly saying no_sanitize only applies to functions and + methods. + +- No longer mention ``reinterpet_cast`` in the invalid constant expression + diagnostic note when in C mode. + +- Clang will now give a more suitale diagnostic for declaration of block + scope identifiers that have external/internal linkage that has an initializer. + (`#57478 `_) + +- A new analysis pass will helps preserve sugar when combining deductions, in an + order agnostic way. This will be in effect when deducing template arguments, + when deducing function return type from multiple return statements, for the + conditional operator, and for most binary operations. Type sugar is combined + in a way that strips the sugar which is different between terms, and preserves + those which are common. + +- Correctly diagnose the use of an integer literal without a suffix whose + underlying type is ``long long`` or ``unsigned long long`` as an extension in + C89 mode . Clang previously only diagnosed if the literal had an explicit + ``LL`` suffix. + +- Clang now correctly diagnoses index that refers past the last possible element + of FAM-like arrays. + +- Clang now correctly emits a warning when dereferencing a void pointer in C mode. + (`#53631 `_) + +- Clang will now diagnose an overload set where a candidate has a constraint that + refers to an expression with a previous error as nothing viable, so that it + doesn't generate strange cascading errors, particularly in cases where a + subsuming constraint fails, which would result in a less-specific overload to + be selected. + +- Add a fix-it hint for the ``-Wdefaulted-function-deleted`` warning to + explicitly delete the function. + +- Fixed an accidental duplicate diagnostic involving the declaration of a + function definition without a prototype which is preceded by a static + declaration of the function with a prototype. + (`#58181 `_) + +- Copy-elided initialization of lock scopes is now handled differently in + ``-Wthread-safety-analysis``: annotations on the move constructor are no + longer taken into account, in favor of annotations on the function returning + the lock scope by value. This could result in new warnings if code depended + on the previous undocumented behavior. As a side effect of this change, + constructor calls outside of initializer expressions are no longer ignored, + which can result in new warnings (or make existing warnings disappear). + +- The wording of diagnostics regarding arithmetic on fixed-sized arrays and + pointers is improved to include the type of the array and whether it's cast + to another type. This should improve comprehension for why an index is + out-of-bounds. + +- Clang now correctly points to the problematic parameter for the ``-Wnonnull`` + warning. (`#58273 `_) + +- Introduced ``-Wcast-function-type-strict`` and + ``-Wincompatible-function-pointer-types-strict`` to warn about function type + mismatches in casts and assignments that may result in runtime indirect call + `Control-Flow Integrity (CFI) + `_ failures. The + ``-Wcast-function-type-strict`` diagnostic is grouped under + ``-Wcast-function-type`` as it identifies a more strict set of potentially + problematic function type casts. + +- Clang will now disambiguate NTTP types when printing diagnostic that contain NTTP types. + (`#57562 `_) + +- Better error recovery for pack expansion of expressions. + (`#58673 `_) + +- Better diagnostics when the user has missed ``auto`` in a declaration. + (`#49129 `_) + +- Clang now diagnoses use of invalid or reserved module names in a module + export declaration. Both are diagnosed as an error, but the diagnostic is + suppressed for use of reserved names in a system header. + +- ``-Winteger-overflow`` will diagnose overflow in more cases. + (`#58944 `_) + +- Clang has an internal limit of 2GB of preprocessed source code per + compilation, including source reachable through imported AST files such as + PCH or modules. When Clang hits this limit, it now produces notes mentioning + which header and source files are consuming large amounts of this space. + ``#pragma clang __debug sloc_usage`` can also be used to request this report. + +- Clang no longer permits the keyword 'bool' in a concept declaration as a + concepts-ts compatibility extension. + +- Clang now diagnoses overflow undefined behavior in a constant expression while + evaluating a compound assignment with remainder as operand. + +- Add ``-Wreturn-local-addr``, a GCC alias for ``-Wreturn-stack-address``. + +- Clang now suppresses ``-Wlogical-op-parentheses`` on ``(x && a || b)`` and ``(a || b && x)`` + only when ``x`` is a string literal. + +- Clang will now reject the GNU extension address of label in coroutines explicitly. + (`#56436 `_) + +- Clang now automatically adds ``[[clang::lifetimebound]]`` to the parameters of + ``std::move, std::forward`` et al, this enables Clang to diagnose more cases + where the returned reference outlives the object. + +- Fix clang not properly diagnosing the failing subexpression when chained + binary operators are used in a ``static_assert`` expression. + +- ``-Wtautological-compare`` missed warnings for tautological comparisons + involving a negative integer literal. + (`#42918 `_) + +- ``-Wcomma`` is no longer emitted for void returning functions. + (`#57151 `_) + +Bug Fixes in This Version +------------------------- + +Bug Fixes to Compiler Builtins +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +- ``stdatomic.h`` will use the internal declarations when targeting pre-C++-23 + on Windows platforms as the MSVC support requires newer C++ standard. + +- Correct ``_Static_assert`` to accept the same set of extended integer + constant expressions as is accpted in other contexts that accept them. + (`#57687 `_) + +- Fix crashes caused when builtin C++ language extension type traits were + instantiated by templates with an unexpected number of arguments. + (`#57008 `_) + +- Fix ``__builtin_assume_aligned`` crash when the 1st arg is array type. + (`#57169 `_) + +- Fixes to builtin template emulation of regular templates. + (`#42102 `_, + `#51928 `_) + +- Fix incorrect handling of inline builtins with asm labels. + +- The builtin type trait ``__is_aggregate`` now returns ``true`` for arrays of incomplete + types in accordance with the suggested fix for `LWG3823 `_ + +Bug Fixes to Attribute Support +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +- Fixes an accepts-invalid bug in C when using a ``_Noreturn`` function + specifier on something other than a function declaration. + (`#56800 `_) + +- No longer assert/miscompile when trying to make a vectorized ``_BitInt`` type + using the ``ext_vector_type`` attribute (the ``vector_size`` attribute was + already properly diagnosing this case). + +- Invalid destructor names are no longer accepted on template classes. + (`#56772 `_) + +- Improve compile-times with large dynamic array allocations with trivial + constructors. + (`#56774 `_) + +- Fix a crash when a ``btf_type_tag`` attribute is applied to the pointee of + a function pointer. + +- In C mode, when ``e1`` has ``__attribute__((noreturn))`` but ``e2`` doesn't, + ``(c ? e1 : e2)`` is no longer considered noreturn. + (`#59792 `_) + +- GNU attributes being applied prior to standard attributes would be handled + improperly, which was corrected to match the behaviour exhibited by GCC. + (`#58229 `_) + +- Fix issue using __attribute__((format)) on non-variadic functions that expect + more than one formatted argument. + +- Clang will now no longer treat a C 'overloadable' function without a prototype as + a variadic function with the attribute. This should make further diagnostics more + clear. + +Bug Fixes to C++ Support +^^^^^^^^^^^^^^^^^^^^^^^^ +- Fix multi-level pack expansion of undeclared function parameters. + (`#56094 `_) + +- Address the thread identification problems in coroutines. + (`#47177 `_, + `#47179 `_) + +- Reject non-type template arguments formed by casting a non-zero integer + to a pointer in pre-C++17 modes, instead of treating them as null + pointers. + +- Fix template arguments of pointer and reference not taking the type as + part of their identity. + (`#47136 `_) + +- Fix handling of unexpanded packs in template argument expressions. + (`#58679 `_) + +- Fix bug with ``using enum`` that could lead to enumerators being treated as if + they were part of an overload set. + (`#58067 `_, + `#59014 `_, + `#54746 `_) + +- Fix bug where constant evaluation treated a pointer to member that points to + a weak member as never being null. Such comparisons are now treated as + non-constant. + +- Fix issue that the standard C++ modules importer will call global + constructor/destructor for the global variables in the importing modules. + (`#59765 `_) + +- Reject in-class defaulting of previously declared comparison operators. + (`#51227 `_) + +- Do not hide templated base members introduced via using-decl in derived class + (useful specially for constrained members). (`#50886 `_) -C2x Feature Support -------------------- -- Implemented `WG14 N2662 `_, - so the [[maybe_unused]] attribute may be applied to a label to silence an - ``-Wunused-label`` warning. -- Implemented `WG14 N2508 `_, - so labels can placed everywhere inside a compound statement. -- Implemented `WG14 N2927 `_, - the Not-so-magic ``typeof`` operator. Also implemented - `WG14 N2930 `_, - renaming ``remove_quals``, so the ``typeof_unqual`` operator is also - supported. Both of these operators are supported only in C2x mode. The - ``typeof`` operator specifies the type of the given parenthesized expression - operand or type name, including all qualifiers. The ``typeof_unqual`` - operator is similar to ``typeof`` except that all qualifiers are removed, - including atomic type qualification and type attributes which behave like a - qualifier, such as an address space attribute. +Concepts Specific Fixes: - .. code-block:: c +- Class member variables are now in scope when parsing a ``requires`` clause. + (`#55216 `_) - __attribute__((address_space(1))) const _Atomic int Val; - typeof(Val) OtherVal; // type is '__attribute__((address_space(1))) const _Atomic int' - typeof_unqual(Val) OtherValUnqual; // type is 'int' +- Required parameter pack to be provided at the end of the concept parameter list. + (`#48182 `_) -- Implemented `WG14 N3042 `_, - Introduce the nullptr constant. This introduces a new type ``nullptr_t``, - declared in ```` which represents the type of the null pointer named - constant, ``nullptr``. This constant is implicitly convertible to any pointer - type and represents a type-safe null value. +- Correctly handle access-checks in requires expression. (`#53364 `_, + `#53334 `_) - Note, there are some known incompatibilities with this same feature in C++. - The following examples were discovered during implementation and are subject - to change depending on how national body comments are resolved by WG14 (C - status is based on standard requirements, not necessarily implementation - behavior): +- Fixed an issue with concept requirement evaluation, where we incorrectly allowed implicit + conversions to bool for a requirement. (`#54524 `_) - .. code-block:: c +- Respect constructor constraints during class template argument deduction (CTAD). + This is the suggested resolution to CWG DR2628. + (`#57646 `_, + `#43829 `_) - nullptr_t null_val; - (nullptr_t)nullptr; // Rejected in C, accepted in C++, Clang accepts - (void)(1 ? nullptr : 0); // Rejected in C, accepted in C++, Clang rejects - (void)(1 ? null_val : 0); // Rejected in C, accepted in C++, Clang rejects - bool b1 = nullptr; // Accepted in C, rejected in C++, Clang rejects - b1 = null_val; // Accepted in C, rejected in C++, Clang rejects - null_val = 0; // Rejected in C, accepted in C++, Clang rejects +- Fix a crash when emitting a concept-related diagnostic. + (`#57415 `_) - void func(nullptr_t); - func(0); // Rejected in C, accepted in C++, Clang rejects +- Fix a crash when trying to form a recovery expression on a call inside a + constraint, which re-evaluated the same constraint. + (`#53213 `_, + `#45736 `_) -- Implemented `WG14 N2975 `_, - Relax requirements for va_start. In C2x mode, functions can now be declared - fully variadic and the ``va_start`` macro no longer requires passing a second - argument (though it accepts a second argument for backwards compatibility). - If a second argument is passed, it is neither expanded nor evaluated in C2x - mode. +- Fix an issue when performing constraints partial ordering on non-template + functions. (`#56154 `_) - .. code-block:: c +- Fix a number of recursively-instantiated constraint issues, which would possibly + result in a stack overflow. + (`#44304 `_, + `#50891 `_) - void func(...) { // Invalid in C17 and earlier, valid in C2x and later. - va_list list; - va_start(list); // Invalid in C17 and earlier, valid in C2x and later. - va_end(list); - } +- Finished implementing C++ DR2565, which results in a requirement becoming + not satisfied in the event of an instantiation failures in a requires expression's + parameter list. We previously handled this correctly in a constraint evaluation + context, but not in a requires clause evaluated as a boolean. -- Diagnose type definitions in the ``type`` argument of ``__builtin_offsetof`` - as a conforming C extension according to - `WG14 N2350 `_. - Also documents the builtin appropriately. Note, a type definition in C++ - continues to be rejected. +Consteval Specific Fixes: -C++ Language Changes in Clang ------------------------------ -- Implemented `DR692 `_, `DR1395 `_, - and `DR1432 `_. The fix for DR1432 is speculative since the - issue is still open and has no proposed resolution at this time. A speculative fix - for DR1432 is needed to prevent regressions that would otherwise occur due to DR692. -- Clang's default C++/ObjC++ standard is now ``gnu++17`` instead of ``gnu++14``. - This means Clang will by default accept code using features from C++17 and - conforming GNU extensions. Projects incompatible with C++17 can add - ``-std=gnu++14`` to their build settings to restore the previous behaviour. -- Implemented DR2358 allowing init captures in lambdas in default arguments. -- implemented `DR2654 `_ which undeprecates - all compound assignements operations on volatile qualified variables. -- Implemented DR2631. Invalid ``consteval`` calls in default arguments and default - member initializers are diagnosed when and if the default is used. - This Fixes `Issue 56379 `_ - and changes the value of ``std::source_location::current()`` - used in default parameters calls compared to previous versions of Clang. +- Fix a crash when generating code coverage information for an + ``if consteval`` statement. + (`#57377 `_) + +- Fixed a crash-on-valid with consteval evaluation of a list-initialized + constructor for a temporary object. + (`#55871 `_) -C++20 Feature Support -^^^^^^^^^^^^^^^^^^^^^ -- Support capturing structured bindings in lambdas - (`P1091R3 `_ and `P1381R1 `_). - This fixes issues `Issue 52720 `_, - `Issue 54300 `_, - `Issue 54301 `_, - and `Issue 49430 `_. -- Consider explicitly defaulted constexpr/consteval special member function - template instantiation to be constexpr/consteval even though a call to such - a function cannot appear in a constant expression. - (C++14 [dcl.constexpr]p6 (CWG DR647/CWG DR1358)) -- Correctly defer dependent immediate function invocations until template instantiation. - This fixes `Issue 55601 `_. -- Implemented "Conditionally Trivial Special Member Functions" (`P0848 `_). - Note: The handling of deleted functions is not yet compliant, as Clang - does not implement `DR1496 `_ - and `DR1734 `_. -- Class member variables are now in scope when parsing a ``requires`` clause. Fixes - `Issue 55216 `_. -- Correctly set expression evaluation context as 'immediate function context' in - consteval functions. - This fixes `Issue 51182 `_. - Fixes an assert crash caused by looking up missing vtable information on ``consteval`` - virtual functions. Fixes `Issue 55065 `_. -- Skip rebuilding lambda expressions in arguments of immediate invocations. - This fixes `Issue 56183 `_, - `Issue 51695 `_, - `Issue 50455 `_, - `Issue 54872 `_, - `Issue 54587 `_. -- Clang now correctly delays the instantiation of function constraints until - the time of checking, which should now allow the libstdc++ ranges implementation - to work for at least trivial examples. This fixes - `Issue 44178 `_. -- Clang implements DR2621, correcting a defect in ``using enum`` handling. The - name is found via ordinary lookup so typedefs are found. -- Implemented `P0634r3 `_, - which removes the requirement for the ``typename`` keyword in certain contexts. -- Implemented The Equality Operator You Are Looking For (`P2468 `_). -- Implemented `P2113R0: Proposed resolution for 2019 comment CA 112 `_ - ([temp.func.order]p6.2.1 is not implemented, matching GCC). -- Implemented `P0857R0 `_, - which specifies constrained lambdas and constrained template *template-parameter*\s. -- Required parameter pack to be provided at the end of the concept parameter list. This - fixes `Issue 48182 `_. + virtual functions. (`#55065 `_) -- Do not hide templated base members introduced via using-decl in derived class - (useful specially for constrained members). Fixes `GH50886 `_. -- Implemented CWG2635 as a Defect Report, which prohibits structured bindings from being constrained. -- Correctly handle access-checks in requires expression. Fixes `GH53364 `_, - `GH53334 `_. +Bug Fixes to AST Handling +^^^^^^^^^^^^^^^^^^^^^^^^^ +- A SubstTemplateTypeParmType can now represent the pack index for a + substitution from an expanded pack. + (`#56099 `_) -- Implemented `P0960R3: `_ - and `P1975R0: `_, - which allows parenthesized aggregate-initialization. +- The template arguments of a variable template being accessed as a + member will now be represented in the AST. -- Fixed an issue with concept requirement evaluation, where we incorrectly allowed implicit - conversions to bool for a requirement. This fixes `GH54524 `_. +Miscellaneous Bug Fixes +^^^^^^^^^^^^^^^^^^^^^^^ +- Clang configuration files are now read through the virtual file system + rather than the physical one, if these are different. -C++2b Feature Support -^^^^^^^^^^^^^^^^^^^^^ +- Fix an issue where -frewrite-includes generated line control directives with + incorrect line numbers in some cases when a header file used an end of line + character sequence that differed from the primary source file. + (`#59736 `_) -- Support label at end of compound statement (`P2324 `_). -- Implemented `P1169R4: static operator() `_ and `P2589R1: static operator[] `_. -- Implemented "char8_t Compatibility and Portability Fix" (`P2513R3 `_). - This change was applied to C++20 as a Defect Report. -- Implemented "Permitting static constexpr variables in constexpr functions" (`P2647R1 _`). -- Implemented `CWG2640 Allow more characters in an n-char sequence _`. +- Clang 14 predeclared some builtin POSIX library functions in ``gnu2x`` mode, + and Clang 15 accidentally stopped predeclaring those functions in that + language mode. Clang 16 now predeclares those functions again. + (`#56607 `_) -CUDA/HIP Language Changes in Clang ----------------------------------- +- Fix the bug of inserting the ``ZeroInitializationFixit`` before the template + argument list of ``VarTemplateSpecializationDecl``. - - Allow the use of ``__noinline__`` as a keyword (instead of ``__attribute__((noinline))``) - in lambda declarations. +Miscellaneous Clang Crashes Fixed +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +- Fix a crash when evaluating a multi-dimensional array's array filler + expression is element-dependent. + (`#50601 `_) + +- Fix an assert that triggers a crash during template name lookup when a type is + incomplete but was not also a TagType. + (`#57387 `_) -Objective-C Language Changes in Clang -------------------------------------- +- Fix a crash when attempting to default a virtual constexpr non-special member + function in a derived class. + (`#57431 `_) -OpenCL C Language Changes in Clang ----------------------------------- +- Fix ``-Wpre-c++17-compat`` crashing Clang when compiling C++20 code which + contains deduced template specializations. + (`#57369 `_, + `#57643 `_, + `#57793 `_) -... +- Fix a crash upon stray coloncolon token in C2x mode. -ABI Changes in Clang --------------------- +- Fix assert that triggers a crash during some types of list initialization that + generate a CXXTemporaryObjectExpr instead of a InitListExpr. + (`#58302 `_, + `#58753 `_, + `#59100 `_) -- GCC doesn't pack non-POD members in packed structs unless the packed - attribute is also specified on the member. Clang historically did perform - such packing. Clang now matches the gcc behavior - (except on Darwin, PS4 and AIX). - You can switch back to the old ABI behavior with the flag: - ``-fclang-abi-compat=15.0``. -- GCC allows POD types to have defaulted special members. Clang historically - classified such types as non-POD (for the purposes of Itanium ABI). Clang now - matches the gcc behavior (except on Darwin, PS4, AIX and z/OS). You can switch - back to the old ABI behavior with the flag: ``-fclang-abi-compat=15.0``. +- Fix a crash where we attempt to define a deleted destructor. + (`#57516 `_) -OpenMP Support in Clang ------------------------ +- Fix an issue that triggers a crash if we instantiate a hidden friend functions. + (`#54457 `_) -... +- Fix an issue that makes Clang crash on lambda template parameters. + (`#57960 `_) -CUDA Support in Clang ---------------------- +- Fixed a crash in C++20 mode in Clang and Clangd when compile source + with compilation errors. + (`#53628 `_) -- Clang now supports CUDA SDK up to 11.8 -- Added support for targeting sm_{87,89,90} GPUs. +- Fix sanity check when value initializing an empty union so that it takes into + account anonymous structs which is a GNU extension. + (`#58800 `_) -LoongArch Support in Clang --------------------------- -- Clang now supports LoongArch. Along with the backend, clang is able to build a - large corpus of Linux applications. Test-suite 100% pass. -- Support basic option ``-march=`` which is used to select the target - architecture, i.e. the basic set of ISA modules to be enabled. Possible values - are ``loongarch64`` and ``la464``. -- Support basic option ``-mabi=`` which is used to select the base ABI type. - Possible values are ``lp64d``, ``lp64f``, ``lp64s``, ``ilp32d``, ``ilp32f`` - and ``ilp32s``. -- Support extended options: ``-msoft-float``, ``-msingle-float``, ``-mdouble-float`` and ``mfpu=``. - See `LoongArch toolchain conventions `_. -RISC-V Support in Clang +Target Specific Changes ----------------------- -- ``sifive-7-rv32`` and ``sifive-7-rv64`` are no longer supported for ``-mcpu``. - Use ``sifive-e76``, ``sifive-s76``, or ``sifive-u74`` instead. -- Native detections via ``-mcpu=native`` and ``-mtune=native`` are supported. -- Fix interaction of ``-mcpu`` and ``-march``, RISC-V backend will take the - architecture extension union of ``-mcpu`` and ``-march`` before, and now will - take architecture extensions from ``-march`` if both are given. -- An ABI mismatch between GCC and Clang that related to the - sign/zero-extension of integer scalars was fixed. -X86 Support in Clang --------------------- +X86 Support +^^^^^^^^^^^ - Support ``-mindirect-branch-cs-prefix`` for call and jmp to indirect thunk. - Fix 32-bit ``__fastcall`` and ``__vectorcall`` ABI mismatch with MSVC. - Add ISA of ``AMX-FP16`` which support ``_tile_dpfp16ps``. @@ -918,27 +972,9 @@ - Support intrinsics of ``_mm(256)_reduce_(add|mul|or|and)_epi8/16``. - Support intrinsics of ``_mm(256)_reduce_(max|min)_ep[i|u]8/16``. -WebAssembly Support in Clang ----------------------------- - -The -mcpu=generic configuration now enables sign-ext and mutable-globals. These -proposals are standardized and available in all major engines. - -DWARF Support in Clang ----------------------- - -Previously when emitting DWARFv4 and tuning for GDB, Clang would use DWARF v2's -``DW_AT_bit_offset`` and ``DW_AT_data_member_location``. Clang now uses DWARF v4's -``DW_AT_data_bit_offset`` regardless of tuning. - -Support for ``DW_AT_data_bit_offset`` was added in GDB 8.0. For earlier versions, -you can use the ``-gdwarf-3`` option to emit compatible DWARF. - -Arm and AArch64 Support in Clang --------------------------------- - +Arm and AArch64 Support +^^^^^^^^^^^^^^^^^^^^^^^ - The target(..) function attributes for AArch64 now accept: - * ``"arch="`` strings, that specify the architecture for a function as per the ``-march`` option. * ``"cpu="`` strings, that specify the cpu for a function as per the ``-mcpu`` option. * ``"tune="`` strings, that specify the tune cpu for a function as per ``-mtune``. @@ -948,7 +984,6 @@ Their presence gave the impression that Clang can correctly generate code for them, which it cannot. - Support has been added for the following processors (-mcpu identifiers in parenthesis): - * Arm Cortex-A715 (cortex-a715). * Arm Cortex-X3 (cortex-x3). * Arm Neoverse V2 (neoverse-v2) @@ -956,6 +991,76 @@ ``-ftrapping-math``, ``-frounding-math``, ``-ffp-model=strict``, and ``-ffp-exception-behaviour=`` are now accepted. +Windows Support +^^^^^^^^^^^^^^^ +- For the MinGW driver, added the options ``-mguard=none``, ``-mguard=cf`` and + ``-mguard=cf-nochecks`` (equivalent to ``/guard:cf-``, ``/guard:cf`` and + ``/guard:cf,nochecks`` in clang-cl) for enabling Control Flow Guard checks + and generation of address-taken function table. +- Switched from SHA1 to BLAKE3 for PDB type hashing / ``-gcodeview-ghash`` +- Fixed code generation with emulated TLS, when the emulated TLS is enabled + by default (with downstream patches; no upstream configurations default + to this configuration, but some mingw downstreams change the default + in this way). +- Improved detection of MinGW cross sysroots for finding sysroots provided + by Linux distributions such as Fedora. Also improved such setups by + avoiding to include ``/usr/include`` among the include paths when cross + compiling with a cross sysroot based in ``/usr``. + +LoongArch Support +^^^^^^^^^^^^^^^^^ +- Clang now supports LoongArch. Along with the backend, clang is able to build a + large corpus of Linux applications. Test-suite 100% pass. +- Support basic option ``-march=`` which is used to select the target + architecture, i.e. the basic set of ISA modules to be enabled. Possible values + are ``loongarch64`` and ``la464``. +- Support basic option ``-mabi=`` which is used to select the base ABI type. + Possible values are ``lp64d``, ``lp64f``, ``lp64s``, ``ilp32d``, ``ilp32f`` + and ``ilp32s``. +- Support extended options: ``-msoft-float``, ``-msingle-float``, ``-mdouble-float`` and ``mfpu=``. + See `LoongArch toolchain conventions `_. + +RISC-V Support +^^^^^^^^^^^^^^ +- ``sifive-7-rv32`` and ``sifive-7-rv64`` are no longer supported for ``-mcpu``. + Use ``sifive-e76``, ``sifive-s76``, or ``sifive-u74`` instead. +- Native detections via ``-mcpu=native`` and ``-mtune=native`` are supported. +- Fix interaction of ``-mcpu`` and ``-march``, RISC-V backend will take the + architecture extension union of ``-mcpu`` and ``-march`` before, and now will + take architecture extensions from ``-march`` if both are given. +- An ABI mismatch between GCC and Clang that related to the + sign/zero-extension of integer scalars was fixed. + +CUDA/HIP Language Changes in Clang +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + - Allow the use of ``__noinline__`` as a keyword (instead of ``__attribute__((noinline))``) + in lambda declarations. + +CUDA Support +^^^^^^^^^^^^ +- Clang now supports CUDA SDK up to 11.8 +- Added support for targeting sm_{87,89,90} GPUs. + +AIX Support +^^^^^^^^^^^ +* When using ``-shared``, the clang driver now invokes llvm-nm to create an + export list if the user doesn't specify one via linker flag or pass an + alternative export control option. + +WebAssembly Support +^^^^^^^^^^^^^^^^^^^ +- The -mcpu=generic configuration now enables sign-ext and mutable-globals. These + proposals are standardized and available in all major engines. + +DWARF Support in Clang +---------------------- +Previously when emitting DWARFv4 and tuning for GDB, Clang would use DWARF v2's +``DW_AT_bit_offset`` and ``DW_AT_data_member_location``. Clang now uses DWARF v4's +``DW_AT_data_bit_offset`` regardless of tuning. + +Support for ``DW_AT_data_bit_offset`` was added in GDB 8.0. For earlier versions, +you can use the ``-gdwarf-3`` option to emit compatible DWARF. + Floating Point Support in Clang ------------------------------- - The driver option ``-menable-unsafe-fp-math`` has been removed. To enable @@ -963,12 +1068,6 @@ ``-ffast-math`` instead. - Add ``__builtin_elementwise_sin`` and ``__builtin_elementwise_cos`` builtins for floating point types only. -Internal API Changes --------------------- - -Build System Changes --------------------- - AST Matchers ------------ - Add ``isInAnoymousNamespace`` matcher to match declarations in an anonymous namespace. @@ -986,9 +1085,6 @@ - Add ``InsertNewlineAtEOF`` option for inserting a newline at EOF if missing. - Add ``LineEnding`` option to deprecate ``DeriveLineEnding`` and ``UseCRLF``. -clang-extdef-mapping --------------------- - libclang -------- - Introduced the new function ``clang_getUnqualifiedType``, which mimics @@ -1035,26 +1131,6 @@ reported. ``-fno-sanitize-memory-param-retval`` restores the previous behavior. -Core Analysis Improvements -========================== - -- ... - -New Issues Found -================ - -- ... - -Python Binding Changes ----------------------- - -The following methods have been added: - -- ... - -Significant Known Problems -========================== - Additional Information ====================== @@ -1066,5 +1142,5 @@ tree. If you have any questions or comments about Clang, please feel free to -contact us on the Discourse forums (Clang Frontend category) +contact us on the `Discourse forums (Clang Frontend category) `_.