Author: Aaron Ballman Date: 2022-01-18T13:41:56-05:00 New Revision: 0d459444e5105d689e6388612784b89a93054944
URL: https://github.com/llvm/llvm-project/commit/0d459444e5105d689e6388612784b89a93054944 DIFF: https://github.com/llvm/llvm-project/commit/0d459444e5105d689e6388612784b89a93054944.diff LOG: Mark ATOMIC_VAR_INIT and ATOMIC_FLAG_INIT as deprecated C17 deprecated ATOMIC_VAR_INIT with the resolution of DR 485. C++ followed suit when adopting P0883R2 for C++20, but additionally chose to deprecate ATOMIC_FLAG_INIT at the same time despite the macro still being required in C. This patch marks both macros as deprecated when appropriate to do so. Added: clang/test/Headers/stdatomic-deprecations.c Modified: clang/docs/ReleaseNotes.rst clang/docs/UsersManual.rst clang/lib/Headers/stdatomic.h Removed: ################################################################################ diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index 9fd22297ae423..de395b5d035ec 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -169,6 +169,11 @@ C Language Changes in Clang which adds ``*_WIDTH`` macros to limits.h and stdint.h to report the bit width of various integer datatypes. +- The ``ATOMIC_VAR_INIT`` macro from ``<stdatomic.h>`` is now diagnosed as + deprecated in C17 and later. The diagnostic can be disabled by defining the + ``_CLANG_DISABLE_CRT_DEPRECATION_WARNINGS`` macro prior to including the + header. + C++ Language Changes in Clang ----------------------------- @@ -176,7 +181,15 @@ C++ Language Changes in Clang C++20 Feature Support ^^^^^^^^^^^^^^^^^^^^^ -... + +- The ``ATOMIC_VAR_INIT`` and ``ATOMIC_FLAG_INIT`` macros from the C standard + library ``<stdatomic.h>`` header are now diagnosed as deprecated in C++20 and + later. Note, the behavior is specific to the inclusion of ``<stdatomic.h>`` + in C++ code; the STL ``<atomic>`` header also controls the behavior of these + macros and is not affected by these changes. The ``<stdatomic.h>`` diagnostic + can be disabled by defining the ``_CLANG_DISABLE_CRT_DEPRECATION_WARNINGS`` + macro prior to including the header. + C++2b Feature Support ^^^^^^^^^^^^^^^^^^^^^ diff --git a/clang/docs/UsersManual.rst b/clang/docs/UsersManual.rst index bdb9705dac637..227884f6aad6a 100644 --- a/clang/docs/UsersManual.rst +++ b/clang/docs/UsersManual.rst @@ -1132,10 +1132,28 @@ A ``#include`` directive which finds a file relative to the current directory is treated as including a system header if the including file is treated as a system header. +Controlling Deprecation Diagnostics in Clang-Provided C Runtime Headers +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +Clang is responsible for providing some of the C runtime headers that cannot be +provided by a platform CRT, such as implementation limits or when compiling in +freestanding mode. Define the ``_CLANG_DISABLE_CRT_DEPRECATION_WARNINGS`` macro +prior to including such a C runtime header to disable the deprecation warnings. +Note that the C Standard Library headers are allowed to transitively include +other standard library headers (see 7.1.2p5), and so the most appropriate use +of this macro is to set it within the build system using ``-D`` or before any +include directives in the translation unit. + +.. code-block:: c + + #define _CLANG_DISABLE_CRT_DEPRECATION_WARNINGS + #include <stdint.h> // Clang CRT deprecation warnings are disabled. + #include <stdatomic.h> // Clang CRT deprecation warnings are disabled. + .. _diagnostics_enable_everything: Enabling All Diagnostics -^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +^^^^^^^^^^^^^^^^^^^^^^^^ In addition to the traditional ``-W`` flags, one can enable **all** diagnostics by passing :option:`-Weverything`. This works as expected with diff --git a/clang/lib/Headers/stdatomic.h b/clang/lib/Headers/stdatomic.h index 1e47bcb2bacfc..780bcc2dfea17 100644 --- a/clang/lib/Headers/stdatomic.h +++ b/clang/lib/Headers/stdatomic.h @@ -44,6 +44,11 @@ extern "C" { /* 7.17.2 Initialization */ #define ATOMIC_VAR_INIT(value) (value) +#if (__STDC_VERSION__ >= 201710L || __cplusplus >= 202002L) && \ + !defined(_CLANG_DISABLE_CRT_DEPRECATION_WARNINGS) +/* ATOMIC_VAR_INIT was deprecated in C17 and C++20. */ +#pragma clang deprecated(ATOMIC_VAR_INIT) +#endif #define atomic_init __c11_atomic_init /* 7.17.3 Order and consistency */ @@ -153,6 +158,10 @@ typedef _Atomic(uintmax_t) atomic_uintmax_t; typedef struct atomic_flag { atomic_bool _Value; } atomic_flag; #define ATOMIC_FLAG_INIT { 0 } +#if __cplusplus >= 202002L && !defined(_CLANG_DISABLE_CRT_DEPRECATION_WARNINGS) +/* ATOMIC_FLAG_INIT was deprecated in C++20 but is not deprecated in C. */ +#pragma clang deprecated(ATOMIC_FLAG_INIT) +#endif /* These should be provided by the libc implementation. */ #ifdef __cplusplus diff --git a/clang/test/Headers/stdatomic-deprecations.c b/clang/test/Headers/stdatomic-deprecations.c new file mode 100644 index 0000000000000..56ee33e16f51a --- /dev/null +++ b/clang/test/Headers/stdatomic-deprecations.c @@ -0,0 +1,18 @@ +// RUN: %clang_cc1 -fsyntax-only -std=c11 %s -verify=okay +// RUN: %clang_cc1 -fsyntax-only -std=c17 %s -verify +// RUN: %clang_cc1 -fsyntax-only -std=c++11 -x c++ %s -verify=okay +// RUN: %clang_cc1 -fsyntax-only -std=c++20 -x c++ %s -verify=cxx,expected +// RUN: %clang_cc1 -fsyntax-only -std=c++20 -x c++ %s -verify=okay -D_CLANG_DISABLE_CRT_DEPRECATION_WARNINGS +// RUN: %clang_cc1 -fsyntax-only -std=c17 %s -verify=okay -D_CLANG_DISABLE_CRT_DEPRECATION_WARNINGS +// +// okay-no-diagnostics + +#include <stdatomic.h> + +void func(void) { + _Atomic int i = ATOMIC_VAR_INIT(12); // expected-warning {{macro 'ATOMIC_VAR_INIT' has been marked as deprecated}} \ + // expected-note@stdatomic.h:* {{macro marked 'deprecated' here}} + #if defined(ATOMIC_FLAG_INIT) // cxx-warning {{macro 'ATOMIC_FLAG_INIT' has been marked as deprecated}} \ + // cxx-note@stdatomic.h:* {{macro marked 'deprecated' here}} + #endif +} _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
