Merge pull request #3 from morinmorin/fix/unused_attribute

Use Boost.Config's BOOST_ATTRIBUTE_UNUSED

doc/static_assert.qbk

@@ -36,7 +36,7 @@ the static assertion will be evaluated at the time the template is instantiated;
 this is particularly useful for validating template parameters.
 
 If the C++0x `static_assert` feature is available, both macros will use it.
-For `BOOST_STATIC_ASSERT(x)`, the error message with be a stringized version of `x`.
+For `BOOST_STATIC_ASSERT(x)`, the error message will be a stringized version of `x`.
 For `BOOST_STATIC_ASSERT_MSG(x, msg)`, the error message will be the `msg` string.
 
 If the C++0x `static_assert` feature is not available, `BOOST_STATIC_ASSERT_MSG(x, msg)`
@@ -151,10 +151,10 @@ using something like this:
    class myclass
    {
    private:
-      BOOST_STATIC_ASSERT((std::numeric_limits<UnsignedInt>::digits >= 16)
-                           && std::numeric_limits<UnsignedInt>::is_specialized
-                           && std::numeric_limits<UnsignedInt>::is_integer
-                           && !std::numeric_limits<UnsignedInt>::is_signed);
+      BOOST_STATIC_ASSERT_MSG(std::numeric_limits<UnsignedInt>::is_specialized, "myclass can only be specialized for types with numeric_limits support.");
+      BOOST_STATIC_ASSERT_MSG(std::numeric_limits<UnsignedInt>::digits >= 16, "Template argument UnsignedInt must have at least 16 bits precision.")
+      BOOST_STATIC_ASSERT_MSG(std::numeric_limits<UnsignedInt>::is_integer, "Template argument UnsignedInt must be an integer.");
+      BOOST_STATIC_ASSERT_MSG(!std::numeric_limits<UnsignedInt>::is_signed, "Template argument UnsignedInt must not be signed.");
    public:
       /* details here */
    };

include/boost/static_assert.hpp

@@ -17,8 +17,21 @@
 #include <boost/config.hpp>
 #include <boost/detail/workaround.hpp>
 
-#ifndef BOOST_NO_STATIC_ASSERT
+#if defined(__GNUC__) && !defined(__GXX_EXPERIMENTAL_CXX0X__)
+//
+// This is horrible, but it seems to be the only we can shut up the
+// "anonymous variadic macros were introduced in C99 [-Wvariadic-macros]"
+// warning that get spewed out otherwise in non-C++11 mode.
+//
+#pragma GCC system_header
+#endif
+
+#ifndef BOOST_NO_CXX11_STATIC_ASSERT
+#  ifndef BOOST_NO_CXX11_VARIADIC_MACROS
+#     define BOOST_STATIC_ASSERT_MSG( ... ) static_assert(__VA_ARGS__)
+#  else
 #     define BOOST_STATIC_ASSERT_MSG( B, Msg ) static_assert( B, Msg )
+#  endif
 #else
 #     define BOOST_STATIC_ASSERT_MSG( B, Msg ) BOOST_STATIC_ASSERT( B )
 #endif
@@ -39,13 +52,25 @@
 // then enable this:
 //
 #if defined(__GNUC__) && ((__GNUC__ > 3) || ((__GNUC__ == 3) && (__GNUC_MINOR__ >= 4)))
+#  ifndef BOOST_NO_CXX11_VARIADIC_MACROS
+#     define BOOST_STATIC_ASSERT_BOOL_CAST( ... ) ((__VA_ARGS__) == 0 ? false : true)
+#  else
 #     define BOOST_STATIC_ASSERT_BOOL_CAST( x ) ((x) == 0 ? false : true)
+#  endif
+#else
+#  ifndef BOOST_NO_CXX11_VARIADIC_MACROS
+#     define BOOST_STATIC_ASSERT_BOOL_CAST( ... ) (bool)(__VA_ARGS__)
 #  else
 #     define BOOST_STATIC_ASSERT_BOOL_CAST(x) (bool)(x)
 #  endif
+#endif
 
-#ifndef BOOST_NO_STATIC_ASSERT
+#ifndef BOOST_NO_CXX11_STATIC_ASSERT
+#  ifndef BOOST_NO_CXX11_VARIADIC_MACROS
+#     define BOOST_STATIC_ASSERT( ... ) static_assert(__VA_ARGS__, #__VA_ARGS__)
+#  else
 #     define BOOST_STATIC_ASSERT( B ) static_assert(B, #B)
+#  endif
 #else
 
 namespace boost{
@@ -84,24 +109,28 @@ template<int x> struct static_assert_test{};
 //
 #if !defined(BOOST_BUGGY_INTEGRAL_CONSTANT_EXPRESSIONS)
 
-#if defined(BOOST_MSVC) && (BOOST_MSVC < 1300)
-// __LINE__ macro broken when -ZI is used see Q199057
-// fortunately MSVC ignores duplicate typedef's.
-#define BOOST_STATIC_ASSERT( B ) \
-   typedef ::boost::static_assert_test<\
-      sizeof(::boost::STATIC_ASSERTION_FAILURE< (bool)( B ) >)\
-      > boost_static_assert_typedef_
-#elif defined(BOOST_MSVC)
+#if defined(BOOST_MSVC) && defined(BOOST_NO_CXX11_VARIADIC_MACROS)
 #define BOOST_STATIC_ASSERT( B ) \
    typedef ::boost::static_assert_test<\
       sizeof(::boost::STATIC_ASSERTION_FAILURE< BOOST_STATIC_ASSERT_BOOL_CAST ( B ) >)>\
          BOOST_JOIN(boost_static_assert_typedef_, __COUNTER__)
-#elif defined(BOOST_INTEL_CXX_VERSION) || defined(BOOST_SA_GCC_WORKAROUND)
+#elif defined(BOOST_MSVC)
+#define BOOST_STATIC_ASSERT(...) \
+   typedef ::boost::static_assert_test<\
+      sizeof(::boost::STATIC_ASSERTION_FAILURE< BOOST_STATIC_ASSERT_BOOL_CAST (__VA_ARGS__) >)>\
+         BOOST_JOIN(boost_static_assert_typedef_, __COUNTER__)
+#elif (defined(BOOST_INTEL_CXX_VERSION) || defined(BOOST_SA_GCC_WORKAROUND))  && defined(BOOST_NO_CXX11_VARIADIC_MACROS)
 // agurt 15/sep/02: a special care is needed to force Intel C++ issue an error 
 // instead of warning in case of failure
 # define BOOST_STATIC_ASSERT( B ) \
     typedef char BOOST_JOIN(boost_static_assert_typedef_, __LINE__) \
         [ ::boost::STATIC_ASSERTION_FAILURE< BOOST_STATIC_ASSERT_BOOL_CAST( B ) >::value ]
+#elif (defined(BOOST_INTEL_CXX_VERSION) || defined(BOOST_SA_GCC_WORKAROUND))  && !defined(BOOST_NO_CXX11_VARIADIC_MACROS)
+// agurt 15/sep/02: a special care is needed to force Intel C++ issue an error 
+// instead of warning in case of failure
+# define BOOST_STATIC_ASSERT(...) \
+    typedef char BOOST_JOIN(boost_static_assert_typedef_, __LINE__) \
+        [ ::boost::STATIC_ASSERTION_FAILURE< BOOST_STATIC_ASSERT_BOOL_CAST( __VA_ARGS__ ) >::value ]
 #elif defined(__sgi)
 // special version for SGI MIPSpro compiler
 #define BOOST_STATIC_ASSERT( B ) \
@@ -119,19 +148,32 @@ template<int x> struct static_assert_test{};
        sizeof(::boost::STATIC_ASSERTION_FAILURE< BOOST_STATIC_ASSERT_BOOL_CAST( B ) >) )
 #else
 // generic version
+#  ifndef BOOST_NO_CXX11_VARIADIC_MACROS
+#     define BOOST_STATIC_ASSERT( ... ) \
+         typedef ::boost::static_assert_test<\
+            sizeof(::boost::STATIC_ASSERTION_FAILURE< BOOST_STATIC_ASSERT_BOOL_CAST( __VA_ARGS__ ) >)>\
+               BOOST_JOIN(boost_static_assert_typedef_, __LINE__) BOOST_ATTRIBUTE_UNUSED
+#  else
 #     define BOOST_STATIC_ASSERT( B ) \
          typedef ::boost::static_assert_test<\
             sizeof(::boost::STATIC_ASSERTION_FAILURE< BOOST_STATIC_ASSERT_BOOL_CAST( B ) >)>\
-         BOOST_JOIN(boost_static_assert_typedef_, __LINE__)
+               BOOST_JOIN(boost_static_assert_typedef_, __LINE__) BOOST_ATTRIBUTE_UNUSED
+#  endif
 #endif
 
 #else
 // alternative enum based implementation:
+#  ifndef BOOST_NO_CXX11_VARIADIC_MACROS
+#    define BOOST_STATIC_ASSERT( ... ) \
+         enum { BOOST_JOIN(boost_static_assert_enum_, __LINE__) \
+            = sizeof(::boost::STATIC_ASSERTION_FAILURE< (bool)( __VA_ARGS__ ) >) }
+#  else
 #    define BOOST_STATIC_ASSERT(B) \
          enum { BOOST_JOIN(boost_static_assert_enum_, __LINE__) \
             = sizeof(::boost::STATIC_ASSERTION_FAILURE< (bool)( B ) >) }
 #  endif
-#endif // defined(BOOST_NO_STATIC_ASSERT)
+#endif
+#endif // defined(BOOST_NO_CXX11_STATIC_ASSERT)
 
 #endif // BOOST_STATIC_ASSERT_HPP
 

meta/libraries.json

@@ -0,0 +1,16 @@
+{
+    "key": "static_assert",
+    "name": "Static Assert",
+    "authors": [
+        "John Maddock"
+    ],
+    "description": "Static assertions (compile time assertions).",
+    "category": [
+        "Correctness",
+        "Generic",
+        "Metaprogramming"
+    ],
+    "maintainers": [
+        "John Maddock <john -at- johnmaddock.co.uk>"
+    ]
+}

static_assert_test.cpp

@@ -58,6 +58,7 @@ struct Bob
 template <class Int, class Char>
 struct Bill
 {
+   BOOST_STATIC_CONSTANT(int, value = 1);
   private:  // can be in private, to avoid namespace pollution
     BOOST_STATIC_ASSERT(sizeof(Int) > sizeof(char));
     BOOST_STATIC_ASSERT_MSG(sizeof(Int) > sizeof(char), "msg9");
@@ -89,6 +90,15 @@ void test_Bill() // BOOST_STATIC_ASSERTs are not triggerred until instantiated
 int main()
 { 
    test_Bill();
+   //
+   // Test variadic macro support:
+   //
+#ifndef BOOST_NO_CXX11_VARIADIC_MACROS
+   BOOST_STATIC_ASSERT(Bill<int, char>::value);
+#ifndef BOOST_NO_CXX11_STATIC_ASSERT
+   BOOST_STATIC_ASSERT_MSG(Bill<int, char>::value, "This is a message");
+#endif
+#endif
    return 0; 
 }