1 /* SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later */ 2 #ifndef PLDM_COMPILER_H 3 #define PLDM_COMPILER_H 4 5 #ifndef __has_attribute 6 #error The libpldm implementation requires __has_attribute 7 #endif 8 9 #include <assert.h> 10 11 static struct { 12 static_assert(__has_attribute(always_inline), 13 "`always_inline` attribute is required"); 14 static_assert(__has_attribute(nonnull), 15 "`nonnull` attribute is required"); 16 static_assert(__has_attribute(unused), 17 "`unused` attribute is required"); 18 static_assert(__has_attribute(warn_unused_result), 19 "`warn_unused_result` attribute is required"); 20 int compliance; 21 } pldm_required_attributes __attribute__((unused)); 22 23 #define LIBPLDM_CC_ALWAYS_INLINE __attribute__((always_inline)) static inline 24 #define LIBPLDM_CC_NONNULL __attribute__((nonnull)) 25 #define LIBPLDM_CC_NONNULL_ARGS(...) __attribute__((nonnull(__VA_ARGS__))) 26 #define LIBPLDM_CC_UNUSED __attribute__((unused)) 27 #define LIBPLDM_CC_WARN_UNUSED_RESULT __attribute__((warn_unused_result)) 28 29 // NOLINTBEGIN(bugprone-macro-parentheses) 30 /** 31 * Require that the given object is of the specified type. 32 * 33 * If the object is not of the required type then a diagnostic will be emitted. 34 * 35 * If you are reading this documentation due to hitting a compilation error 36 * passing through the macro, then you have a type error in your code that must 37 * be fixed. Despite the compiler output, the error is _not_ that some array 38 * is negatively sized, the array is negatively sized _because_ you have a type 39 * error. 40 * 41 * How this works: 42 * 43 * If the type of @p obj is not equivalent to the provided type @p type then 44 * we force the compiler to evaluate sizeof on a negatively-sized array. The 45 * C standard requires that the integer constant expression that specifies 46 * the array length must be greater than zero. Failure to meet this constraint 47 * generally terminates compilation of the translation unit as any other result 48 * cannot be handled in a sensible way. The array size is derived to an integer 49 * constant expression from a type eqivalence evaluated using _Generic() 50 * allowing us to stay within the language standard. The default generic 51 * association, representing a type mismatch, yields -1. 52 * 53 * pldm_require_obj_type() was introduced into the libpldm implementation to 54 * enable use of the pldm_msgbuf_extract*() APIs for objects that may or may not 55 * reside in a packed struct. See src/msgbuf.h for more details. 56 * 57 * @param obj The name of the object to evaluate 58 * @param type The required type of @p obj 59 * 60 * @return The expression either yields 1, or compilation is terminated 61 */ 62 #define pldm_require_obj_type(obj, type) \ 63 ((void)(sizeof( \ 64 struct { char buf[_Generic((obj), type: 1, default: -1)]; }))) 65 // NOLINTEND(bugprone-macro-parentheses) 66 67 #endif 68