diff options
Diffstat (limited to 'absl/base/attributes.h')
| -rw-r--r-- | absl/base/attributes.h | 57 |
1 files changed, 43 insertions, 14 deletions
diff --git a/absl/base/attributes.h b/absl/base/attributes.h index b1883b6d..291ad89e 100644 --- a/absl/base/attributes.h +++ b/absl/base/attributes.h @@ -100,7 +100,7 @@ // ABSL_PRINTF_ATTRIBUTE // ABSL_SCANF_ATTRIBUTE // -// Tells the compiler to perform `printf` format std::string checking if the +// Tells the compiler to perform `printf` format string checking if the // compiler supports it; see the 'format' attribute in // <http://gcc.gnu.org/onlinedocs/gcc-4.7.0/gcc/Function-Attributes.html>. // @@ -155,7 +155,12 @@ // ABSL_ATTRIBUTE_WEAK // // Tags a function as weak for the purposes of compilation and linking. -#if ABSL_HAVE_ATTRIBUTE(weak) || (defined(__GNUC__) && !defined(__clang__)) +// 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) || \ + (defined(__GNUC__) && !defined(__clang__))) && \ + !(defined(__llvm__) && defined(_WIN32)) #undef ABSL_ATTRIBUTE_WEAK #define ABSL_ATTRIBUTE_WEAK __attribute__((weak)) #define ABSL_HAVE_ATTRIBUTE_WEAK 1 @@ -296,13 +301,13 @@ // ABSL_HAVE_ATTRIBUTE_SECTION // -// Indicates whether labeled sections are supported. Labeled sections are not -// supported on Darwin/iOS. +// Indicates whether labeled sections are supported. Weak symbol support is +// a prerequisite. Labeled sections are not supported on Darwin/iOS. #ifdef ABSL_HAVE_ATTRIBUTE_SECTION #error ABSL_HAVE_ATTRIBUTE_SECTION cannot be directly set #elif (ABSL_HAVE_ATTRIBUTE(section) || \ (defined(__GNUC__) && !defined(__clang__))) && \ - !defined(__APPLE__) + !defined(__APPLE__) && ABSL_HAVE_ATTRIBUTE_WEAK #define ABSL_HAVE_ATTRIBUTE_SECTION 1 // ABSL_ATTRIBUTE_SECTION @@ -397,17 +402,28 @@ // ABSL_MUST_USE_RESULT // -// Tells the compiler to warn about unused return values for functions declared -// with this macro. The macro must appear as the very first part of a function -// declaration or definition: +// Tells the compiler to warn about unused results. // -// Example: +// When annotating a function, it must appear as the first part of the +// declaration or definition. The compiler will warn if the return value from +// such a function is unused: // // ABSL_MUST_USE_RESULT Sprocket* AllocateSprocket(); +// AllocateSprocket(); // Triggers a warning. +// +// When annotating a class, it is equivalent to annotating every function which +// returns an instance. +// +// class ABSL_MUST_USE_RESULT Sprocket {}; +// Sprocket(); // Triggers a warning. +// +// Sprocket MakeSprocket(); +// MakeSprocket(); // Triggers a warning. +// +// Note that references and pointers are not instances: // -// This placement has the broadest compatibility with GCC, Clang, and MSVC, with -// both defs and decls, and with GCC-style attributes, MSVC declspec, C++11 -// and C++17 attributes. +// Sprocket* SprocketPointer(); +// SprocketPointer(); // Does *not* trigger a warning. // // ABSL_MUST_USE_RESULT allows using cast-to-void to suppress the unused result // warning. For that, warn_unused_result is used only for clang but not for gcc. @@ -494,14 +510,27 @@ #define ABSL_XRAY_LOG_ARGS(N) #endif +// ABSL_ATTRIBUTE_REINITIALIZES +// +// Indicates that a member function reinitializes the entire object to a known +// state, independent of the previous state of the object. +// +// The clang-tidy check bugprone-use-after-move allows member functions marked +// with this attribute to be called on objects that have been moved from; +// without the attribute, this would result in a use-after-move warning. +#if ABSL_HAVE_CPP_ATTRIBUTE(clang::reinitializes) +#define ABSL_ATTRIBUTE_REINITIALIZES [[clang::reinitializes]] +#else +#define ABSL_ATTRIBUTE_REINITIALIZES +#endif + // ----------------------------------------------------------------------------- // Variable Attributes // ----------------------------------------------------------------------------- // ABSL_ATTRIBUTE_UNUSED // -// Prevents the compiler from complaining about or optimizing away variables -// that appear unused. +// Prevents the compiler from complaining about variables that appear unused. #if ABSL_HAVE_ATTRIBUTE(unused) || (defined(__GNUC__) && !defined(__clang__)) #undef ABSL_ATTRIBUTE_UNUSED #define ABSL_ATTRIBUTE_UNUSED __attribute__((__unused__)) |