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Section: 17.15.4 [stdalign.h.syn], 17.15.5 [stdbool.h.syn] Status: LEWG Submitter: GB Opened: 2022-11-10 Last modified: 2022-11-11
Priority: Not Prioritized
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Discussion:
This is the resolution for NB comments:
GB-081:
C2x defines alignas as a keyword, so <stdalign.h> is empty in C2x. C++23 should deprecate the __alignas_is_defined macro now, rather than wait until a future C++ standard is based on C2x. That gives users longer to prepare for the removal of the macro.
Recommended change: Deprecate __alignas_is_defined and move it to Annex D. Maybe keep a note in 17.15.4 [stdalign.h.syn] that the macro is present but deprecated.
GB-082:
C2x supports bool as a built-in type, and true and false as keywords. Consequently, C2x marks the __bool_true_false_are_defined as obsolescent. C++23 should deprecate that attribute now, rather than wait until a future C++ standard is based on C2x. That gives users longer to prepare for the removal of the macro.
Recommended change: Deprecate __bool_true_false_are_defined and move it to Annex D. Maybe keep a note in 17.15.5 [stdbool.h.syn] that the macro is present but deprecated.
[Kona 2022-11-10; Jonathan provides wording]
[Kona 2022-11-10; Waiting for LEWG electronic polling]
Proposed resolution:
This wording is relative to N4917.
Modify 17.15.4 [stdalign.h.syn] as indicated:
17.14.4 Header <stdalign.h> synopsis [stdalign.h.syn]
#define __alignas_is_defined 1-1- The contents of the C++ header <stdalign.h> are the same as the C standard library header <stdalign.h>, with the following changes: The header <stdalign.h> does not define a macro named alignas. The macro __alignas_is_defined ( [depr.c.macros]) is deprecated.
See also: ISO C 7.15
Modify 17.15.5 [stdbool.h.syn] as indicated:
17.14.5 Header <stdbool.h> synopsis [stdbool.h.syn]
#define __bool_true_false_are_defined 1-1- The contents of the C++ header <stdbool.h> are the same as the C standard library header <stdbool.h>, with the following changes: The header <stdbool.h> does not define macros named bool, true, or false. The macro __bool_true_false_are_defined ( [depr.c.macros]) is deprecated.
See also: ISO C 7.18
D?? Deprecated C macros [depr.c.macros]
-1- The header <stdalign.h> has the following macro:
#define __alignas_is_defined 1-2- The header <stdbool.h> has the following macro:
#define __bool_true_false_are_defined 1