diff options
Diffstat (limited to 'third_party/abseil-cpp/absl/base/attributes.h')
| -rw-r--r-- | third_party/abseil-cpp/absl/base/attributes.h | 224 |
1 files changed, 169 insertions, 55 deletions
diff --git a/third_party/abseil-cpp/absl/base/attributes.h b/third_party/abseil-cpp/absl/base/attributes.h index ff138629d1..e3907827d6 100644 --- a/third_party/abseil-cpp/absl/base/attributes.h +++ b/third_party/abseil-cpp/absl/base/attributes.h @@ -18,8 +18,6 @@ // These macros are used within Abseil and allow the compiler to optimize, where // applicable, certain function calls. // -// This file is used for both C and C++! -// // Most macros here are exposing GCC or Clang features, and are stubbed out for // other compilers. // @@ -32,34 +30,12 @@ // of them are not supported in older version of Clang. Thus, we check // `__has_attribute()` first. If the check fails, we check if we are on GCC and // assume the attribute exists on GCC (which is verified on GCC 4.7). -// -// ----------------------------------------------------------------------------- -// Sanitizer Attributes -// ----------------------------------------------------------------------------- -// -// Sanitizer-related attributes are not "defined" in this file (and indeed -// are not defined as such in any file). To utilize the following -// sanitizer-related attributes within your builds, define the following macros -// within your build using a `-D` flag, along with the given value for -// `-fsanitize`: -// -// * `ADDRESS_SANITIZER` + `-fsanitize=address` (Clang, GCC 4.8) -// * `MEMORY_SANITIZER` + `-fsanitize=memory` (Clang-only) -// * `THREAD_SANITIZER + `-fsanitize=thread` (Clang, GCC 4.8+) -// * `UNDEFINED_BEHAVIOR_SANITIZER` + `-fsanitize=undefined` (Clang, GCC 4.9+) -// * `CONTROL_FLOW_INTEGRITY` + -fsanitize=cfi (Clang-only) -// -// Example: -// -// // Enable branches in the Abseil code that are tagged for ASan: -// $ bazel build --copt=-DADDRESS_SANITIZER --copt=-fsanitize=address -// --linkopt=-fsanitize=address *target* -// -// Since these macro names are only supported by GCC and Clang, we only check -// for `__GNUC__` (GCC or Clang) and the above macros. + #ifndef ABSL_BASE_ATTRIBUTES_H_ #define ABSL_BASE_ATTRIBUTES_H_ +#include "absl/base/config.h" + // ABSL_HAVE_ATTRIBUTE // // A function-like feature checking macro that is a wrapper around @@ -143,7 +119,7 @@ #if ABSL_HAVE_ATTRIBUTE(disable_tail_calls) #define ABSL_HAVE_ATTRIBUTE_NO_TAIL_CALL 1 #define ABSL_ATTRIBUTE_NO_TAIL_CALL __attribute__((disable_tail_calls)) -#elif defined(__GNUC__) && !defined(__clang__) +#elif defined(__GNUC__) && !defined(__clang__) && !defined(__e2k__) #define ABSL_HAVE_ATTRIBUTE_NO_TAIL_CALL 1 #define ABSL_ATTRIBUTE_NO_TAIL_CALL \ __attribute__((optimize("no-optimize-sibling-calls"))) @@ -155,14 +131,14 @@ // ABSL_ATTRIBUTE_WEAK // // 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 +// Weak attributes did not work properly in LLVM's Windows backend before +// 9.0.0, so disable them there. See https://bugs.llvm.org/show_bug.cgi?id=37598 // 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(__MINGW32__) + (!defined(_WIN32) || __clang_major__ < 9) && !defined(__MINGW32__) #undef ABSL_ATTRIBUTE_WEAK #define ABSL_ATTRIBUTE_WEAK __attribute__((weak)) #define ABSL_HAVE_ATTRIBUTE_WEAK 1 @@ -234,7 +210,7 @@ // out of bounds or does other scary things with memory. // NOTE: GCC supports AddressSanitizer(asan) since 4.8. // https://gcc.gnu.org/gcc-4.8/changes.html -#if defined(__GNUC__) +#if ABSL_HAVE_ATTRIBUTE(no_sanitize_address) #define ABSL_ATTRIBUTE_NO_SANITIZE_ADDRESS __attribute__((no_sanitize_address)) #else #define ABSL_ATTRIBUTE_NO_SANITIZE_ADDRESS @@ -242,13 +218,13 @@ // ABSL_ATTRIBUTE_NO_SANITIZE_MEMORY // -// Tells the MemorySanitizer to relax the handling of a given function. All -// "Use of uninitialized value" warnings from such functions will be suppressed, -// and all values loaded from memory will be considered fully initialized. -// This attribute is similar to the ADDRESS_SANITIZER attribute above, but deals -// with initialized-ness rather than addressability issues. +// Tells the MemorySanitizer to relax the handling of a given function. All "Use +// of uninitialized value" warnings from such functions will be suppressed, and +// all values loaded from memory will be considered fully initialized. This +// attribute is similar to the ABSL_ATTRIBUTE_NO_SANITIZE_ADDRESS attribute +// above, but deals with initialized-ness rather than addressability issues. // NOTE: MemorySanitizer(msan) is supported by Clang but not GCC. -#if defined(__clang__) +#if ABSL_HAVE_ATTRIBUTE(no_sanitize_memory) #define ABSL_ATTRIBUTE_NO_SANITIZE_MEMORY __attribute__((no_sanitize_memory)) #else #define ABSL_ATTRIBUTE_NO_SANITIZE_MEMORY @@ -259,7 +235,7 @@ // Tells the ThreadSanitizer to not instrument a given function. // NOTE: GCC supports ThreadSanitizer(tsan) since 4.8. // https://gcc.gnu.org/gcc-4.8/changes.html -#if defined(__GNUC__) +#if ABSL_HAVE_ATTRIBUTE(no_sanitize_thread) #define ABSL_ATTRIBUTE_NO_SANITIZE_THREAD __attribute__((no_sanitize_thread)) #else #define ABSL_ATTRIBUTE_NO_SANITIZE_THREAD @@ -271,8 +247,10 @@ // where certain behavior (eg. division by zero) is being used intentionally. // NOTE: GCC supports UndefinedBehaviorSanitizer(ubsan) since 4.9. // https://gcc.gnu.org/gcc-4.9/changes.html -#if defined(__GNUC__) && \ - (defined(UNDEFINED_BEHAVIOR_SANITIZER) || defined(ADDRESS_SANITIZER)) +#if ABSL_HAVE_ATTRIBUTE(no_sanitize_undefined) +#define ABSL_ATTRIBUTE_NO_SANITIZE_UNDEFINED \ + __attribute__((no_sanitize_undefined)) +#elif ABSL_HAVE_ATTRIBUTE(no_sanitize) #define ABSL_ATTRIBUTE_NO_SANITIZE_UNDEFINED \ __attribute__((no_sanitize("undefined"))) #else @@ -283,7 +261,7 @@ // // Tells the ControlFlowIntegrity sanitizer to not instrument a given function. // See https://clang.llvm.org/docs/ControlFlowIntegrity.html for details. -#if defined(__GNUC__) && defined(CONTROL_FLOW_INTEGRITY) +#if ABSL_HAVE_ATTRIBUTE(no_sanitize) #define ABSL_ATTRIBUTE_NO_SANITIZE_CFI __attribute__((no_sanitize("cfi"))) #else #define ABSL_ATTRIBUTE_NO_SANITIZE_CFI @@ -293,7 +271,7 @@ // // Tells the SafeStack to not instrument a given function. // See https://clang.llvm.org/docs/SafeStack.html for details. -#if defined(__GNUC__) && defined(SAFESTACK_SANITIZER) +#if ABSL_HAVE_ATTRIBUTE(no_sanitize) #define ABSL_ATTRIBUTE_NO_SANITIZE_SAFESTACK \ __attribute__((no_sanitize("safe-stack"))) #else @@ -303,10 +281,7 @@ // ABSL_ATTRIBUTE_RETURNS_NONNULL // // Tells the compiler that a particular function never returns a null pointer. -#if ABSL_HAVE_ATTRIBUTE(returns_nonnull) || \ - (defined(__GNUC__) && \ - (__GNUC__ > 5 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 9)) && \ - !defined(__clang__)) +#if ABSL_HAVE_ATTRIBUTE(returns_nonnull) #define ABSL_ATTRIBUTE_RETURNS_NONNULL __attribute__((returns_nonnull)) #else #define ABSL_ATTRIBUTE_RETURNS_NONNULL @@ -343,8 +318,16 @@ // `__start_ ## name` and `__stop_ ## name` symbols to bracket the section. // This functionality is supported by GNU linker. #ifndef ABSL_ATTRIBUTE_SECTION_VARIABLE +#ifdef _AIX +// __attribute__((section(#name))) on AIX is achived by using the `.csect` psudo +// op which includes an additional integer as part of its syntax indcating +// alignment. If data fall under different alignments then you might get a +// compilation error indicating a `Section type conflict`. +#define ABSL_ATTRIBUTE_SECTION_VARIABLE(name) +#else #define ABSL_ATTRIBUTE_SECTION_VARIABLE(name) __attribute__((section(#name))) #endif +#endif // ABSL_DECLARE_ATTRIBUTE_SECTION_VARS // @@ -507,8 +490,10 @@ // packages/targets, as this may lead to conflicting definitions of functions at // link-time. // +// XRay isn't currently supported on Android: +// https://github.com/android/ndk/issues/368 #if ABSL_HAVE_CPP_ATTRIBUTE(clang::xray_always_instrument) && \ - !defined(ABSL_NO_XRAY_ATTRIBUTES) + !defined(ABSL_NO_XRAY_ATTRIBUTES) && !defined(__ANDROID__) #define ABSL_XRAY_ALWAYS_INSTRUMENT [[clang::xray_always_instrument]] #define ABSL_XRAY_NEVER_INSTRUMENT [[clang::xray_never_instrument]] #if ABSL_HAVE_CPP_ATTRIBUTE(clang::xray_log_args) @@ -544,6 +529,13 @@ // ABSL_ATTRIBUTE_UNUSED // // Prevents the compiler from complaining about variables that appear unused. +// +// For code or headers that are assured to only build with C++17 and up, prefer +// just using the standard '[[maybe_unused]]' directly over this macro. +// +// Due to differences in positioning requirements between the old, compiler +// specific __attribute__ syntax and the now standard [[maybe_unused]], this +// macro does not attempt to take advantage of '[[maybe_unused]]'. #if ABSL_HAVE_ATTRIBUTE(unused) || (defined(__GNUC__) && !defined(__clang__)) #undef ABSL_ATTRIBUTE_UNUSED #define ABSL_ATTRIBUTE_UNUSED __attribute__((__unused__)) @@ -564,13 +556,19 @@ // ABSL_ATTRIBUTE_PACKED // // 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. +// structure, but instead to reduce its alignment to 1. +// +// Therefore, DO NOT APPLY THIS ATTRIBUTE TO STRUCTS CONTAINING ATOMICS. Doing +// so can cause atomic variables to be mis-aligned and silently violate +// atomicity on x86. +// +// 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 @@ -592,6 +590,79 @@ #define ABSL_ATTRIBUTE_FUNC_ALIGN(bytes) #endif +// ABSL_FALLTHROUGH_INTENDED +// +// Annotates implicit fall-through between switch labels, allowing a case to +// indicate intentional fallthrough and turn off warnings about any lack of a +// `break` statement. The ABSL_FALLTHROUGH_INTENDED macro should be followed by +// a semicolon and can be used in most places where `break` can, provided that +// no statements exist between it and the next switch label. +// +// Example: +// +// switch (x) { +// case 40: +// case 41: +// if (truth_is_out_there) { +// ++x; +// ABSL_FALLTHROUGH_INTENDED; // Use instead of/along with annotations +// // in comments +// } else { +// return x; +// } +// case 42: +// ... +// +// Notes: When supported, GCC and Clang can issue a warning on switch labels +// with unannotated fallthrough using the warning `-Wimplicit-fallthrough`. See +// clang documentation on language extensions for details: +// https://clang.llvm.org/docs/AttributeReference.html#fallthrough-clang-fallthrough +// +// When used with unsupported compilers, the ABSL_FALLTHROUGH_INTENDED macro has +// no effect on diagnostics. In any case this macro has no effect on runtime +// behavior and performance of code. + +#ifdef ABSL_FALLTHROUGH_INTENDED +#error "ABSL_FALLTHROUGH_INTENDED should not be defined." +#elif ABSL_HAVE_CPP_ATTRIBUTE(fallthrough) +#define ABSL_FALLTHROUGH_INTENDED [[fallthrough]] +#elif ABSL_HAVE_CPP_ATTRIBUTE(clang::fallthrough) +#define ABSL_FALLTHROUGH_INTENDED [[clang::fallthrough]] +#elif ABSL_HAVE_CPP_ATTRIBUTE(gnu::fallthrough) +#define ABSL_FALLTHROUGH_INTENDED [[gnu::fallthrough]] +#else +#define ABSL_FALLTHROUGH_INTENDED \ + do { \ + } while (0) +#endif + +// ABSL_DEPRECATED() +// +// Marks a deprecated class, struct, enum, function, method and variable +// declarations. The macro argument is used as a custom diagnostic message (e.g. +// suggestion of a better alternative). +// +// Examples: +// +// class ABSL_DEPRECATED("Use Bar instead") Foo {...}; +// +// ABSL_DEPRECATED("Use Baz() instead") void Bar() {...} +// +// template <typename T> +// ABSL_DEPRECATED("Use DoThat() instead") +// void DoThis(); +// +// Every usage of a deprecated entity will trigger a warning when compiled with +// clang's `-Wdeprecated-declarations` option. This option is turned off by +// default, but the warnings will be reported by clang-tidy. +#if defined(__clang__) && defined(__cplusplus) && __cplusplus >= 201103L +#define ABSL_DEPRECATED(message) __attribute__((deprecated(message))) +#endif + +#ifndef ABSL_DEPRECATED +#define ABSL_DEPRECATED(message) +#endif + // ABSL_CONST_INIT // // A variable declaration annotated with the `ABSL_CONST_INIT` attribute will @@ -618,4 +689,47 @@ #define ABSL_CONST_INIT #endif // ABSL_HAVE_CPP_ATTRIBUTE(clang::require_constant_initialization) +// ABSL_ATTRIBUTE_PURE_FUNCTION +// +// ABSL_ATTRIBUTE_PURE_FUNCTION is used to annotate declarations of "pure" +// functions. A function is pure if its return value is only a function of its +// arguments. The pure attribute prohibits a function from modifying the state +// of the program that is observable by means other than inspecting the +// function's return value. Declaring such functions with the pure attribute +// allows the compiler to avoid emitting some calls in repeated invocations of +// the function with the same argument values. +// +// Example: +// +// ABSL_ATTRIBUTE_PURE_FUNCTION int64_t ToInt64Milliseconds(Duration d); +#if ABSL_HAVE_CPP_ATTRIBUTE(gnu::pure) +#define ABSL_ATTRIBUTE_PURE_FUNCTION [[gnu::pure]] +#elif ABSL_HAVE_ATTRIBUTE(pure) +#define ABSL_ATTRIBUTE_PURE_FUNCTION __attribute__((pure)) +#else +#define ABSL_ATTRIBUTE_PURE_FUNCTION +#endif + +// ABSL_ATTRIBUTE_LIFETIME_BOUND indicates that a resource owned by a function +// parameter or implicit object parameter is retained by the return value of the +// annotated function (or, for a parameter of a constructor, in the value of the +// constructed object). This attribute causes warnings to be produced if a +// temporary object does not live long enough. +// +// When applied to a reference parameter, the referenced object is assumed to be +// retained by the return value of the function. When applied to a non-reference +// parameter (for example, a pointer or a class type), all temporaries +// referenced by the parameter are assumed to be retained by the return value of +// the function. +// +// See also the upstream documentation: +// https://clang.llvm.org/docs/AttributeReference.html#lifetimebound +#if ABSL_HAVE_CPP_ATTRIBUTE(clang::lifetimebound) +#define ABSL_ATTRIBUTE_LIFETIME_BOUND [[clang::lifetimebound]] +#elif ABSL_HAVE_ATTRIBUTE(lifetimebound) +#define ABSL_ATTRIBUTE_LIFETIME_BOUND __attribute__((lifetimebound)) +#else +#define ABSL_ATTRIBUTE_LIFETIME_BOUND +#endif + #endif // ABSL_BASE_ATTRIBUTES_H_ |