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 #include <libpldm/compiler.h> 6 7 #ifndef __has_attribute 8 #error The libpldm implementation requires __has_attribute 9 #endif 10 11 #include <assert.h> 12 13 static struct { 14 static_assert(__has_attribute(always_inline), 15 "`always_inline` attribute is required"); 16 static_assert(__has_attribute(nonnull), 17 "`nonnull` attribute is required"); 18 static_assert(__has_attribute(unused), 19 "`unused` attribute is required"); 20 static_assert(__has_attribute(warn_unused_result), 21 "`warn_unused_result` attribute is required"); 22 int compliance; 23 } pldm_required_attributes __attribute__((unused)); 24 25 #ifndef LIBPLDM_CC_ALWAYS_INLINE 26 #error Missing definition for LIBPLDM_ALWAYS_INLINE 27 #endif 28 29 #ifndef LIBPLDM_CC_NONNULL 30 #error Missing definition for LIBPLDM_CC_NONNULL 31 #endif 32 33 #define LIBPLDM_CC_NONNULL_ARGS(...) __attribute__((nonnull(__VA_ARGS__))) 34 #define LIBPLDM_CC_UNUSED __attribute__((unused)) 35 #define LIBPLDM_CC_WARN_UNUSED_RESULT __attribute__((warn_unused_result)) 36 37 // NOLINTBEGIN(bugprone-macro-parentheses) 38 /** 39 * Require that the given object is of the specified type. 40 * 41 * If the object is not of the required type then a diagnostic will be emitted. 42 * 43 * If you are reading this documentation due to hitting a compilation error 44 * passing through the macro, then you have a type error in your code that must 45 * be fixed. Despite the compiler output, the error is _not_ that some array 46 * is negatively sized, the array is negatively sized _because_ you have a type 47 * error. 48 * 49 * How this works: 50 * 51 * If the type of @p obj is not equivalent to the provided type @p type then 52 * we force the compiler to evaluate sizeof on a negatively-sized array. The 53 * C standard requires that the integer constant expression that specifies 54 * the array length must be greater than zero. Failure to meet this constraint 55 * generally terminates compilation of the translation unit as any other result 56 * cannot be handled in a sensible way. The array size is derived to an integer 57 * constant expression from a type eqivalence evaluated using _Generic() 58 * allowing us to stay within the language standard. The default generic 59 * association, representing a type mismatch, yields -1. 60 * 61 * pldm_require_obj_type() was introduced into the libpldm implementation to 62 * enable use of the pldm_msgbuf_extract*() APIs for objects that may or may not 63 * reside in a packed struct. See src/msgbuf.h for more details. 64 * 65 * @param obj The name of the object to evaluate 66 * @param type The required type of @p obj 67 * 68 * @return The expression either yields 1, or compilation is terminated 69 */ 70 #define pldm_require_obj_type(obj, type) \ 71 ((void)(sizeof( \ 72 struct { char buf[_Generic((obj), type: 1, default: -1)]; }))) 73 // NOLINTEND(bugprone-macro-parentheses) 74 75 #endif 76