[PATCH] D112221: Mark ATOMIC_VAR_INIT and ATOMIC_FLAG_INIT as deprecated

[Aaron Ballman via Phabricator via cfe-commits]

aaron.ballman updated this revision to Diff 394626.
aaron.ballman added a comment.

Dropped changes to libc++ based on review feedback.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D112221/new/

https://reviews.llvm.org/D112221

Files:
  clang/docs/ReleaseNotes.rst
  clang/docs/UsersManual.rst
  clang/lib/Headers/stdatomic.h
  clang/test/Headers/stdatomic-deprecations.c


Index: clang/test/Headers/stdatomic-deprecations.c
===================================================================
--- /dev/null
+++ 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 at stdatomic.h:* {{macro marked 'deprecated' here}}
+  #if defined(ATOMIC_FLAG_INIT) // cxx-warning {{macro 'ATOMIC_FLAG_INIT' has been marked as deprecated}} \
+                                // cxx-note at stdatomic.h:* {{macro marked 'deprecated' here}}
+  #endif
+}
Index: clang/lib/Headers/stdatomic.h
===================================================================
--- clang/lib/Headers/stdatomic.h
+++ clang/lib/Headers/stdatomic.h
@@ -44,6 +44,11 @@
 /* 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 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
Index: clang/docs/UsersManual.rst
===================================================================
--- clang/docs/UsersManual.rst
+++ clang/docs/UsersManual.rst
@@ -1114,10 +1114,25 @@
 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
+without also disabling other deprecation warnings.
+
+.. code-block:: c
+
+  #include <stdint.h> // May include Clang CRT deprecation warnings
+  #define _CLANG_DISABLE_CRT_DEPRECATION_WARNINGS
+  #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
Index: clang/docs/ReleaseNotes.rst
===================================================================
--- clang/docs/ReleaseNotes.rst
+++ clang/docs/ReleaseNotes.rst
@@ -156,6 +156,13 @@
   stabilized, so this type should not yet be used in interfaces that require
   ABI stability.
 
+ - The ``ATOMIC_VAR_INIT`` macro from ``<stdatomic.h>`` is now diagnosed as
+   deprecated in both C (C17 and later) and C++ (C++20 and later), and
+   ``ATOMIC_FLAG_INIT`` is now diagnosed as deprecated in C++ (C++20 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
 -----------------------------
 


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