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Define unconstify() and unvolatize() for C++.

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These two macros wouldn't work if used in an inline function definition
in a header seen by g++, because __builtin_types_compatible_p is only
available in C.  Redirect to standard C++ const_cast (which also
adds/removes volatile despite its name).

Per cpluspluscheck failure in a development branch.

Suggested-by: Peter Eisentraut <peter@eisentraut.org>
Discussion: https://postgr.es/m/CA%2BhUKGK3OXFjkOyZiw-DgL2bUqk9by1uGuCnViJX786W%2BfyDSw%40mail.gmail.com
This commit is contained in:
Thomas Munro 2023-12-12 09:31:44 +13:00
parent 0a5c46a7a4
commit baf7c93ed5
1 changed files with 4 additions and 1 deletions
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5
src/include/c.h
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@ -1245,7 +1245,10 @@ typedef union PGAlignedXLogBlock
* Note that this only works in function scope, not for global variables (it'd
* be nice, but not trivial, to improve that).
*/
#if defined(HAVE__BUILTIN_TYPES_COMPATIBLE_P)
#if defined(__cplusplus)
#define unconstify(underlying_type, expr) const_cast<underlying_type>(expr)
#define unvolatize(underlying_type, expr) const_cast<underlying_type>(expr)
#elif defined(HAVE__BUILTIN_TYPES_COMPATIBLE_P)
#define unconstify(underlying_type, expr) \
(StaticAssertExpr(__builtin_types_compatible_p(__typeof(expr), const underlying_type), \
"wrong cast"), \