source: branches/stable/TEMPLATES/cxxforward.h

Last change on this file was 18384, checked in by westram, 6 years ago
  • add UNUSED attribute to structs defined in namespace final_unsuggest
    • attempt to silence bogus suggestions
    • does not work well for 8.x series; keep it anyway.
File size: 7.0 KB
Line 
1// ================================================================ //
2//                                                                  //
3//   File      : cxxforward.h                                       //
4//   Purpose   : macros for forward usage of C++11 features         //
5//               w/o loosing compatibility to C++03 compilers       //
6//                                                                  //
7//   Coded by Ralf Westram (coder@reallysoft.de) in December 2012   //
8//   Institute of Microbiology (Technical University Munich)        //
9//   http://www.arb-home.de/                                        //
10//                                                                  //
11// ================================================================ //
12
13#ifndef CXXFORWARD_H
14#define CXXFORWARD_H
15
16#ifndef GCCVER_H
17#include "gccver.h"
18#endif
19#if defined(__cplusplus)
20# if (GCC_VERSION_CODE >= 407)
21#  if (__cplusplus == 199711L)
22#  else
23#   if (__cplusplus == 201103L)
24#    define ARB_ENABLE11_FEATURES
25#   else
26#    if (__cplusplus == 201402L)
27#     define ARB_ENABLE11_FEATURES
28#     define ARB_ENABLE14_FEATURES
29#    else
30#     error Unknown C++ standard defined in __cplusplus
31#    endif
32#   endif
33#  endif
34# endif
35#else
36# error C compilation includes cxxforward.h
37#endif
38
39#ifndef _GLIBCXX_CSTDDEF
40#include <cstddef>
41#endif
42
43#ifdef ARB_ENABLE14_FEATURES
44// C++14 is enabled starting with gcc 6.1 in ../Makefile@USE_Cxx14
45//
46// Use #ifdef Cxx14 to insert conditional sections using full C++14
47# define Cxx14 1
48
49// C++14 allows more complex constexpr functions (e.g. multiple commands; void return type)
50# define CONSTEXPR_INLINE_Cxx14 constexpr inline
51
52#else
53// backward (non C++14) compatibility defines:
54
55# define CONSTEXPR_INLINE_Cxx14 inline
56
57#endif
58
59
60#ifdef ARB_ENABLE11_FEATURES
61// C++11 is enabled starting with gcc 4.7 in ../Makefile@USE_Cxx11
62//
63// Full support for C++11 is available starting with gcc 4.8.
64// Use #ifdef Cxx11 to insert conditional sections using full C++11
65# if (GCC_VERSION_CODE >= 408)
66#  define Cxx11 1
67# endif
68
69// allows static member initialisation in class definition:
70# define CONSTEXPR        constexpr
71# define CONSTEXPR_INLINE constexpr inline
72
73// allows to protect overloading functions against signature changes of overload functions:
74# define OVERRIDE override
75
76// allows additional optimization of virtual calls
77// (does not only allow to replace virtual by a normal call, it also allows inlining!)
78# define FINAL_TYPE     final
79# define FINAL_OVERRIDE final override
80
81# define NULp nullptr
82
83#else
84// backward (non C++11) compatibility defines:
85
86# if (GCC_VERSION_CODE >= 406)
87#  define CONSTEXPR        constexpr
88# else
89#  define CONSTEXPR        const
90# endif
91
92# define CONSTEXPR_INLINE  inline
93# define OVERRIDE
94# define FINAL_TYPE
95# define FINAL_OVERRIDE
96
97# define NULp NULL
98// [Note: defining NULp as 0 causes failing tests if compiled with gcc 4.4.3; com-errors somewhere in AISC interface]
99
100#endif
101
102// Note: additional (experimental) constexpr macros are defined in ../CORE/arb_assert.h@ASSERTING_CONSTEXPR_INLINE
103
104
105// make use of gcc 7.x implicit fallthrough warnings:
106#if (GCC_VERSION_CODE >= 700)
107# define FALLTHROUGH [[gnu::fallthrough]]
108// Note: Cxx17 may use [[fallthrough]]
109#else
110# define FALLTHROUGH
111// Note: clang may know [[clang::fallthrough]]
112#endif
113
114// hide warnings about intentionally unused things:
115#if (GCC_VERSION_CODE >= 700)
116# define UNUSED [[gnu::unused]]
117// Note: Cxx17 may use [[unused]]
118#else
119# define UNUSED __attribute__((unused))
120#endif
121
122
123// allow to hide unwanted final suggestions
124#ifdef SUGGESTS_FINAL
125
126# if (GCC_VERSION_CODE >= 900)
127// test with older gcc versions?! SUGGESTS_FINAL defined for gcc 5.0++
128#  define EXTENDED_FINAL_WARNING_SUPPRESSION // gcc 9.1 became too smart (for old suppression methods)
129# endif
130
131namespace final_unsuggest { struct fakedarg { }; };
132# define NF_JOIN(X,Y) X##Y
133
134# ifdef EXTENDED_FINAL_WARNING_SUPPRESSION
135
136// declare fake-ctor used by MARK_NONFINAL_CLASS (has to be added into BASE)
137#  define PREPARE_MARK_NONFINAL_CLASS(CLASS) explicit CLASS(final_unsuggest::fakedarg)
138
139#  define MARK_NONFINAL_CLASS(BASE)                                             \
140    namespace final_unsuggest {                                                 \
141        struct UNUSED NF_JOIN(unfinalize,BASE) final : BASE {                   \
142            NF_JOIN(unfinalize,BASE)() : BASE(final_unsuggest::fakedarg()) {}   \
143        };                                                                      \
144    }
145
146// PARAMS has to contain parentheses and attributes like const!
147// RETURN has to contain 'return' keyword or may be completely empty
148#  define MARK_NONFINAL__INTERNAL(BASE,RETYPE,METHOD_NAME,PARAMS,RETURN)        \
149    namespace final_unsuggest {                                                 \
150        struct UNUSED NF_JOIN(BASE,METHOD_NAME) final : BASE {                  \
151            RETYPE METHOD_NAME PARAMS override {                                \
152                RETURN;                                                         \
153            }                                                                   \
154        };                                                                      \
155    }
156
157#  if (GCC_VERSION_CODE >= 901) && (GCC_VERSION_CODE <= 903) // (please do not activate for all future versions, test each of them)
158// some final type suggestion even do not get silenced by the above code.
159// => disable -Wsuggest-final-types locally using the following define.
160#   define GCC_TOO_SMART_FOR_USEFUL_FINAL_TYPE_SUGGESTION
161#  endif
162
163# else // !EXTENDED_FINAL_WARNING_SUPPRESSION
164
165#  define PREPARE_MARK_NONFINAL_CLASS(CLASS)
166#  define MARK_NONFINAL_CLASS(BASE)                             \
167    namespace final_unsuggest {                                 \
168        struct UNUSED NF_JOIN(unfinalize,BASE) final : BASE {   \
169        };                                                      \
170    }
171// PARAMS has to contain parentheses and attributes like const!
172// RETURN is ignored here (needed in version above)
173#  define MARK_NONFINAL__INTERNAL(BASE,RETYPE,METHOD_NAME,PARAMS,RETURN)        \
174    namespace final_unsuggest {                                                 \
175        struct UNUSED NF_JOIN(BASE,METHOD_NAME) final : BASE {                  \
176            inline RETYPE METHOD_NAME PARAMS override;                          \
177        };                                                                      \
178    }
179
180# endif
181
182#else
183
184# define PREPARE_MARK_NONFINAL_CLASS(CLASS)
185# define MARK_NONFINAL_CLASS(BASE)
186# define MARK_NONFINAL__INTERNAL(BASE,RETURN_TYPE,METHOD_NAME,PARAMS,RETURN)
187
188#endif
189
190
191#define MARK_NONFINAL_DTOR(BASE) MARK_NONFINAL_CLASS(BASE)
192
193// like MARK_NONFINAL_FUNCTION, but void "result":
194# define MARK_NONFINAL_FUNCTION(BASE,RETYPE,METHOD_NAME,PARAMS,RETVAL) MARK_NONFINAL__INTERNAL(BASE,RETYPE,METHOD_NAME,PARAMS,return RETVAL)
195# define MARK_NONFINAL_METHOD(BASE,METHOD_NAME,PARAMS)                 MARK_NONFINAL__INTERNAL(BASE,void,METHOD_NAME,PARAMS,)
196
197
198#undef ARB_ENABLE11_FEATURES
199#undef ARB_ENABLE14_FEATURES
200
201#else
202#error cxxforward.h included twice
203#endif // CXXFORWARD_H
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