Use C++'s standardized [[noreturn]] attribute

Summary:Use C++'s standardized `[[noreturn]]` attribute.

All supported compilers (and some unsupported compilers) also support the standardized syntax.

GCC >= 4.8, Clang >= 3.0, and MSVC >= 2015 have direct support for the C++'s standardized way of writing the attribute.

Clang - http://goo.gl/ftJGVM
GCC 4.8.2 - http://goo.gl/ORCVOD
ICC 13.0.1 - http://goo.gl/I5tn5I
MSVC 2015 - https://msdn.microsoft.com/en-us/library/hh567368.aspx

(Regardling Clang, earlier versions may support it. 3.0 was the earliest Clang version listed at godbolt.com, so that's as far back as I went.)

Therefore, we no longer need to use the compiler-specific syntaxes, or use preprocessor macros with per-compiler definitions:

    __attribute__((__noreturn__))
    __attribute__((noreturn))
    __declspec(noreturn)

Reviewed By: Orvid

Differential Revision: D3073621

fb-gh-sync-id: 32d4771d1bf1974693b8574fa2d39c9559872945
shipit-source-id: 32d4771d1bf1974693b8574fa2d39c9559872945

folly/Exception.h

@@ -37,24 +37,19 @@ namespace folly {
 // The *Explicit functions take an explicit value for errno.
 
 // Helper to throw std::system_error
-FOLLY_NORETURN void throwSystemErrorExplicit(int err, const char*);
-inline void throwSystemErrorExplicit(int err, const char* msg) {
+[[noreturn]] inline void throwSystemErrorExplicit(int err, const char* msg) {
   throw std::system_error(err, std::system_category(), msg);
 }
 
 template <class... Args>
-FOLLY_NORETURN void throwSystemErrorExplicit(int, Args&&... args);
-template <class... Args>
-void throwSystemErrorExplicit(int err, Args&&... args) {
+[[noreturn]] void throwSystemErrorExplicit(int err, Args&&... args) {
   throwSystemErrorExplicit(
       err, to<fbstring>(std::forward<Args>(args)...).c_str());
 }
 
 // Helper to throw std::system_error from errno and components of a string
 template <class... Args>
-FOLLY_NORETURN void throwSystemError(Args&&... args);
-template <class... Args>
-void throwSystemError(Args&&... args) {
+[[noreturn]] void throwSystemError(Args&&... args) {
   throwSystemErrorExplicit(errno, std::forward<Args>(args)...);
 }
 

folly/FormatArg.h

@@ -82,7 +82,7 @@ struct FormatArg {
   template <typename... Args>
   std::string errorStr(Args&&... args) const;
   template <typename... Args>
-  FOLLY_NORETURN void error(Args&&... args) const;
+  [[noreturn]] void error(Args&&... args) const;
 
   /**
    * Full argument string, as passed in to the constructor.

folly/Indestructible.h

@@ -101,7 +101,7 @@ class Indestructible final {
     }
   }
 
-  FOLLY_NORETURN FOLLY_NOINLINE static void fail() {
+  [[noreturn]] FOLLY_NOINLINE static void fail() {
     LOG(FATAL) << "Indestructible is not initialized";
   }
 

folly/Portability.h

@@ -79,15 +79,6 @@ constexpr bool kHasUnalignedAccess = false;
 # define FOLLY_DEPRECATED(msg)
 #endif
 
-// noreturn
-#if defined(_MSC_VER)
-# define FOLLY_NORETURN __declspec(noreturn)
-#elif defined(__clang__) || defined(__GNUC__)
-# define FOLLY_NORETURN __attribute__((__noreturn__))
-#else
-# define FOLLY_NORETURN
-#endif
-
 // noinline
 #ifdef _MSC_VER
 # define FOLLY_NOINLINE __declspec(noinline)

folly/SafeAssert.h

@@ -43,10 +43,12 @@
 
 namespace folly { namespace detail {
 
-FOLLY_NORETURN void assertionFailure(const char* expr, const char* msg,
-                      const char* file, unsigned int line,
-                      const char* function);
-
+[[noreturn]] void assertionFailure(
+    const char* expr,
+    const char* msg,
+    const char* file,
+    unsigned int line,
+    const char* function);
 }}  // namespace folly
 
 #endif /* FOLLY_SAFEASSERT_H_ */

folly/Subprocess.cpp

@@ -210,8 +210,7 @@ struct ChildErrorInfo {
   int errnoValue;
 };
 
-FOLLY_NORETURN void childError(int errFd, int errCode, int errnoValue);
-void childError(int errFd, int errCode, int errnoValue) {
+[[noreturn]] void childError(int errFd, int errCode, int errnoValue) {
   ChildErrorInfo info = {errCode, errnoValue};
   // Write the error information over the pipe to our parent process.
   // We can't really do anything else if this write call fails.

folly/detail/FunctionalExcept.h

@@ -23,12 +23,12 @@
 
 FOLLY_NAMESPACE_STD_BEGIN
 
-FOLLY_NORETURN void __throw_length_error(const char* msg);
-FOLLY_NORETURN void __throw_logic_error(const char* msg);
-FOLLY_NORETURN void __throw_out_of_range(const char* msg);
+[[noreturn]] void __throw_length_error(const char* msg);
+[[noreturn]] void __throw_logic_error(const char* msg);
+[[noreturn]] void __throw_out_of_range(const char* msg);
 
 #ifdef _MSC_VER
-FOLLY_NORETURN void __throw_bad_alloc();
+[[noreturn]] void __throw_bad_alloc();
 #endif
 
 FOLLY_NAMESPACE_STD_END

folly/experimental/bser/Load.cpp

@@ -25,7 +25,7 @@ namespace bser {
 static dynamic parseBser(Cursor& curs);
 
 template <typename... ARGS>
-static FOLLY_NORETURN void throwDecodeError(Cursor& curs, ARGS&&... args) {
+[[noreturn]] static void throwDecodeError(Cursor& curs, ARGS&&... args) {
   throw BserDecodeError(folly::to<std::string>(std::forward<ARGS>(args)...,
                                                " with ",
                                                curs.length(),

folly/experimental/exception_tracer/ExceptionTracerLib.cpp

@@ -27,11 +27,12 @@
 namespace __cxxabiv1 {
 
 extern "C" {
-FOLLY_NORETURN void __cxa_throw(void* thrownException,
-                                std::type_info* type,
-                                void (*destructor)(void*));
+void __cxa_throw(
+    void* thrownException,
+    std::type_info* type,
+    void (*destructor)(void*)) __attribute__((__noreturn__));
 void* __cxa_begin_catch(void* excObj) throw();
-FOLLY_NORETURN void __cxa_rethrow(void);
+void __cxa_rethrow(void) __attribute__((__noreturn__));
 void __cxa_rethrow(void);
 void __cxa_end_catch(void);
 }

folly/experimental/io/HugePageUtil.cpp

@@ -41,9 +41,7 @@ using namespace folly;
 
 namespace {
 
-FOLLY_NORETURN void usage(const char* name);
-
-void usage(const char* name) {
+[[noreturn]] void usage(const char* name) {
   std::cerr << folly::format(
       "Usage: {0}\n"
       "         list all huge page sizes and their mount points\n"

folly/experimental/test/NestedCommandLineAppExample.cpp

@@ -55,11 +55,11 @@ class Concatenator {
   size_t lineNumber_ = 0;
 };
 
-FOLLY_NORETURN void throwOutputError() {
+[[noreturn]] void throwOutputError() {
   throw OutputError(folly::errnoStr(errno).toStdString());
 }
 
-FOLLY_NORETURN void throwInputError() {
+[[noreturn]] void throwInputError() {
   throw InputError(folly::errnoStr(errno).toStdString());
 }