diff options
Diffstat (limited to 'absl/base/attributes.h')
| -rw-r--r-- | absl/base/attributes.h | 23 |
1 files changed, 18 insertions, 5 deletions
diff --git a/absl/base/attributes.h b/absl/base/attributes.h index a7da62af..ff138629 100644 --- a/absl/base/attributes.h +++ b/absl/base/attributes.h @@ -157,10 +157,12 @@ // Tags a function as weak for the purposes of compilation and linking. // Weak attributes currently do not work properly in LLVM's Windows backend, // so disable them there. See https://bugs.llvm.org/show_bug.cgi?id=37598 -// for futher information. -#if (ABSL_HAVE_ATTRIBUTE(weak) || \ +// for further information. +// The MinGW compiler doesn't complain about the weak attribute until the link +// step, presumably because Windows doesn't use ELF binaries. +#if (ABSL_HAVE_ATTRIBUTE(weak) || \ (defined(__GNUC__) && !defined(__clang__))) && \ - !(defined(__llvm__) && defined(_WIN32)) + !(defined(__llvm__) && defined(_WIN32)) && !defined(__MINGW32__) #undef ABSL_ATTRIBUTE_WEAK #define ABSL_ATTRIBUTE_WEAK __attribute__((weak)) #define ABSL_HAVE_ATTRIBUTE_WEAK 1 @@ -561,7 +563,19 @@ // ABSL_ATTRIBUTE_PACKED // -// Prevents the compiler from padding a structure to natural alignment +// Instructs the compiler not to use natural alignment for a tagged data +// structure, but instead to reduce its alignment to 1. This attribute can +// either be applied to members of a structure or to a structure in its +// entirety. Applying this attribute (judiciously) to a structure in its +// entirety to optimize the memory footprint of very commonly-used structs is +// fine. Do not apply this attribute to a structure in its entirety if the +// purpose is to control the offsets of the members in the structure. Instead, +// apply this attribute only to structure members that need it. +// +// When applying ABSL_ATTRIBUTE_PACKED only to specific structure members the +// natural alignment of structure members not annotated is preserved. Aligned +// member accesses are faster than non-aligned member accesses even if the +// targeted microprocessor supports non-aligned accesses. #if ABSL_HAVE_ATTRIBUTE(packed) || (defined(__GNUC__) && !defined(__clang__)) #define ABSL_ATTRIBUTE_PACKED __attribute__((__packed__)) #else @@ -599,7 +613,6 @@ // // Note that this attribute is redundant if the variable is declared constexpr. #if ABSL_HAVE_CPP_ATTRIBUTE(clang::require_constant_initialization) -// NOLINTNEXTLINE(whitespace/braces) #define ABSL_CONST_INIT [[clang::require_constant_initialization]] #else #define ABSL_CONST_INIT |