From: arighi Date: Mon, 30 Aug 2010 15:48:18 +0000 (+0000) Subject: countof(): perform a compile time type checking for static arrays X-Git-Tag: 2.6.0~192 X-Git-Url: https://codewiz.org/gitweb?a=commitdiff_plain;h=59ed30d944d4ec2bd41675f64a4cedeb26d2f8b2;p=bertos.git countof(): perform a compile time type checking for static arrays The macro countof() can only work with static arrays, so throw a compile time error if a pointer is passed as argument. NOTE: this only works with gcc (not g++). git-svn-id: https://src.develer.com/svnoss/bertos/trunk@4202 38d2e660-2303-0410-9eaa-f027e97ec537 --- diff --git a/bertos/cfg/compiler.h b/bertos/cfg/compiler.h index 907b23e6..e8a76ab1 100644 --- a/bertos/cfg/compiler.h +++ b/bertos/cfg/compiler.h @@ -531,7 +531,22 @@ typedef unsigned char sigmask_t; /**< Type for signal masks. */ * * \note This macro is non-standard, but implements a very common idiom */ - #define countof(a) (sizeof(a) / sizeof(*(a))) + #if defined(__GNUC__) && !defined(__cplusplus) + /* + * Perform a compile time type checking: countof() can only + * work with static arrays, so throw a compile time error if a + * pointer is passed as argument. + * + * NOTE: the construct __builtin_types_compatible_p() is only + * available for C. + */ + #define countof(a) (sizeof(a) / sizeof(*(a)) + \ + sizeof(typeof(int[1 - 2 * \ + !!__builtin_types_compatible_p(typeof(a), \ + typeof(&a[0]))])) * 0) + #else + #define countof(a) (sizeof(a) / sizeof(*(a))) + #endif #endif #ifndef alignof /**