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 static_assert(__has_attribute(cleanup), 23 "`cleanup` attribute is required"); 24 int compliance; 25 } pldm_required_attributes __attribute__((unused)); 26 27 #ifndef LIBPLDM_CC_ALWAYS_INLINE 28 #error Missing definition for LIBPLDM_ALWAYS_INLINE 29 #endif 30 31 #ifndef LIBPLDM_CC_NONNULL 32 #error Missing definition for LIBPLDM_CC_NONNULL 33 #endif 34 35 #define LIBPLDM_CC_CLEANUP(fn) __attribute__((cleanup(fn))) 36 #define LIBPLDM_CC_NONNULL_ARGS(...) __attribute__((nonnull(__VA_ARGS__))) 37 #define LIBPLDM_CC_UNUSED __attribute__((unused)) 38 #define LIBPLDM_CC_WARN_UNUSED_RESULT __attribute__((warn_unused_result)) 39 40 // NOLINTBEGIN(bugprone-macro-parentheses) 41 /** 42 * Require that the given object is of the specified type. 43 * 44 * If the object is not of the required type then a diagnostic will be emitted. 45 * 46 * If you are reading this documentation due to hitting a compilation error 47 * passing through the macro, then you have a type error in your code that must 48 * be fixed. Despite the compiler output, the error is _not_ that some array 49 * is negatively sized, the array is negatively sized _because_ you have a type 50 * error. 51 * 52 * How this works: 53 * 54 * If the type of @p obj is not equivalent to the provided type @p type then 55 * we force the compiler to evaluate sizeof on a negatively-sized array. The 56 * C standard requires that the integer constant expression that specifies 57 * the array length must be greater than zero. Failure to meet this constraint 58 * generally terminates compilation of the translation unit as any other result 59 * cannot be handled in a sensible way. The array size is derived to an integer 60 * constant expression from a type eqivalence evaluated using _Generic() 61 * allowing us to stay within the language standard. The default generic 62 * association, representing a type mismatch, yields -1. 63 * 64 * pldm_require_obj_type() was introduced into the libpldm implementation to 65 * enable use of the pldm_msgbuf_extract*() APIs for objects that may or may not 66 * reside in a packed struct. See src/msgbuf.h for more details. 67 * 68 * @param obj The name of the object to evaluate 69 * @param type The required type of @p obj 70 * 71 * @return The expression either yields 1, or compilation is terminated 72 */ 73 #define pldm_require_obj_type(obj, type) \ 74 ((void)(sizeof( \ 75 struct { char buf[_Generic((obj), type: 1, default: -1)]; }))) 76 // NOLINTEND(bugprone-macro-parentheses) 77 78 #endif 79