[mesos] 01/15: Revamped attribute handling in stout.

[be...@apache.org]

This is an automated email from the ASF dual-hosted git repository.

bennoe pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/mesos.git

commit d5b6ba7f40cb10724d92554f44cae5bfd39ac961
Author: Benno Evers <be...@mesosphere.com>
AuthorDate: Thu Nov 7 14:55:13 2019 +0100

    Revamped attribute handling in stout.
    
    This makes several changes to the attribute compatibility layer
    provided by stout:
    
      * Add a new `STOUT_HAS_CPP_ATTRIBUTE` macro to test compiler
        support for a given attribute.
      * Renamed the non-namespaced `NORETURN` macro to `STOUT_NORETURN`.
      * Preferred the use of the standardized `[[noreturn]]` syntax
        if supported by the compiler.
      * Fixed previous usages of `NORETURN` in the stout codebase.
      * Added support for the `[[nodiscard]]` attribute.
    
    Review: https://reviews.apache.org/r/71734/
---
 3rdparty/stout/include/stout/abort.hpp         |  6 ++++--
 3rdparty/stout/include/stout/attributes.hpp    | 26 ++++++++++++++++++++++----
 3rdparty/stout/include/stout/exit.hpp          |  2 +-
 3rdparty/stout/include/stout/unimplemented.hpp |  2 +-
 3rdparty/stout/include/stout/unreachable.hpp   |  2 +-
 5 files changed, 29 insertions(+), 9 deletions(-)

diff --git a/3rdparty/stout/include/stout/abort.hpp b/3rdparty/stout/include/stout/abort.hpp
index 43ed5ce..1917106 100644
--- a/3rdparty/stout/include/stout/abort.hpp
+++ b/3rdparty/stout/include/stout/abort.hpp
@@ -40,7 +40,8 @@
 #define ABORT(...) _Abort(_ABORT_PREFIX, __VA_ARGS__)
 
 
-inline NORETURN void _Abort(const char* prefix, const char* message)
+STOUT_NORETURN
+inline void _Abort(const char* prefix, const char* message)
 {
 #ifndef __WINDOWS__
   const size_t prefix_len = strlen(prefix);
@@ -87,7 +88,8 @@ inline NORETURN void _Abort(const char* prefix, const char* message)
 }
 
 
-inline NORETURN void _Abort(const char* prefix, const std::string& message)
+STOUT_NORETURN
+inline void _Abort(const char* prefix, const std::string& message)
 {
   _Abort(prefix, message.c_str());
 }
diff --git a/3rdparty/stout/include/stout/attributes.hpp b/3rdparty/stout/include/stout/attributes.hpp
index aa377db..a02ee79 100644
--- a/3rdparty/stout/include/stout/attributes.hpp
+++ b/3rdparty/stout/include/stout/attributes.hpp
@@ -13,12 +13,30 @@
 #ifndef __STOUT_ATTRIBUTES_HPP__
 #define __STOUT_ATTRIBUTES_HPP__
 
+#ifdef __has_cpp_attribute
+#  define STOUT_HAS_CPP_ATTRIBUTE(x) __has_cpp_attribute(x)
+#else
+#  define STOUT_HAS_CPP_ATTRIBUTE(x) 0
+#endif
 
-#ifdef __WINDOWS__
-#define NORETURN __declspec(noreturn)
+// We unconditionally require compiler support for `noreturn`,
+// both for legacy reasons and because the presence of this
+// attribute might affect code generation.
+#if STOUT_HAS_CPP_ATTRIBUTE(noreturn) > 0
+#  define STOUT_NORETURN [[noreturn]]
+#elif defined(__WINDOWS__)
+#  define STOUT_NORETURN __declspec(noreturn)
 #else
-#define NORETURN __attribute__((noreturn))
-#endif // __WINDOWS__
+#  define STOUT_NORETURN __attribute__((noreturn))
+#endif
+
+// Non-namespaced version for backwards compatibility.
+#define NORETURN STOUT_NORETURN
 
+#if STOUT_HAS_CPP_ATTRIBUTE(nodiscard) > 0
+#  define STOUT_NODISCARD [[nodiscard]]
+#else
+#  define STOUT_NODISCARD
+#endif
 
 #endif // __STOUT_ATTRIBUTES_HPP__
diff --git a/3rdparty/stout/include/stout/exit.hpp b/3rdparty/stout/include/stout/exit.hpp
index 34585a0..25721d4 100644
--- a/3rdparty/stout/include/stout/exit.hpp
+++ b/3rdparty/stout/include/stout/exit.hpp
@@ -62,7 +62,7 @@ struct __Exit
     stream() << "EXIT with status " << _status << ": ";
   }
 
-  NORETURN ~__Exit()
+  STOUT_NORETURN ~__Exit()
   {
     message.Flush();
     exit(status);
diff --git a/3rdparty/stout/include/stout/unimplemented.hpp b/3rdparty/stout/include/stout/unimplemented.hpp
index ab6caa8..168a2f8 100644
--- a/3rdparty/stout/include/stout/unimplemented.hpp
+++ b/3rdparty/stout/include/stout/unimplemented.hpp
@@ -28,7 +28,7 @@
 
 #define UNIMPLEMENTED Unimplemented(__func__, __FILE__, __LINE__)
 
-NORETURN inline void Unimplemented(
+STOUT_NORETURN inline void Unimplemented(
     const char* function,
     const char* file,
     const int line)
diff --git a/3rdparty/stout/include/stout/unreachable.hpp b/3rdparty/stout/include/stout/unreachable.hpp
index d4b3bb0..e33bc01 100644
--- a/3rdparty/stout/include/stout/unreachable.hpp
+++ b/3rdparty/stout/include/stout/unreachable.hpp
@@ -22,7 +22,7 @@
 #define UNREACHABLE() Unreachable(__FILE__, __LINE__)
 
 
-inline NORETURN void Unreachable(const char* file, int line)
+STOUT_NORETURN inline void Unreachable(const char* file, int line)
 {
   std::cerr << "Reached unreachable statement at " << file << ':'
             << line << std::endl;