ARB
cxxforward.h
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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 // make use of gcc 7.x implicit fallthrough warnings:
103 #if (GCC_VERSION_CODE >= 700)
104 # define FALLTHROUGH [[gnu::fallthrough]]
105 // Note: Cxx17 may use [[fallthrough]]
106 #else
107 # define FALLTHROUGH
108 // Note: clang may know [[clang::fallthrough]]
109 #endif
110 
111 
112 // Note: additional (experimental) constexpr macros are defined in ../CORE/arb_assert.h@ASSERTING_CONSTEXPR_INLINE
113 
114 // allow to hide unwanted final suggestions
115 #ifdef SUGGESTS_FINAL
116 
117 # if (GCC_VERSION_CODE >= 900)
118 // test with older gcc versions?! SUGGESTS_FINAL defined for gcc 5.0++
119 # define EXTENDED_FINAL_WARNING_SUPPRESSION // gcc 9.1 became too smart (for old suppression methods)
120 # endif
121 
122 namespace final_unsuggest { struct fakedarg { }; };
123 # define NF_JOIN(X,Y) X##Y
124 
125 # ifdef EXTENDED_FINAL_WARNING_SUPPRESSION
126 
127 // declare fake-ctor used by MARK_NONFINAL_CLASS (has to be added into BASE)
128 # define PREPARE_MARK_NONFINAL_CLASS(CLASS) explicit CLASS(final_unsuggest::fakedarg)
129 
130 # define MARK_NONFINAL_CLASS(BASE) \
131  namespace final_unsuggest { \
132  struct NF_JOIN(unfinalize,BASE) final : BASE { \
133  NF_JOIN(unfinalize,BASE)() : BASE(final_unsuggest::fakedarg()) {} \
134  }; \
135  }
136 
137 // PARAMS has to contain parentheses and attributes like const!
138 // RETURN has to contain 'return' keyword or may be completely empty
139 # define MARK_NONFINAL__INTERNAL(BASE,RETYPE,METHOD_NAME,PARAMS,RETURN) \
140  namespace final_unsuggest { \
141  struct NF_JOIN(BASE,METHOD_NAME) final : BASE { \
142  RETYPE METHOD_NAME PARAMS override { \
143  RETURN; \
144  } \
145  }; \
146  }
147 
148 # if (GCC_VERSION_CODE == 901) || (GCC_VERSION_CODE == 902) // (please do not activate for all future versions, test each of them)
149 // some final type suggestion even do not get silenced by the above code.
150 // => disable -Wsuggest-final-types locally using the following define.
151 # define GCC_TOO_SMART_FOR_USEFUL_FINAL_TYPE_SUGGESTION
152 # endif
153 
154 # else // !EXTENDED_FINAL_WARNING_SUPPRESSION
155 
156 # define PREPARE_MARK_NONFINAL_CLASS(CLASS)
157 # define MARK_NONFINAL_CLASS(BASE) \
158  namespace final_unsuggest { \
159  struct NF_JOIN(unfinalize,BASE) final : BASE { \
160  }; \
161  }
162 // PARAMS has to contain parentheses and attributes like const!
163 // RETURN is ignored here (needed in version above)
164 # define MARK_NONFINAL__INTERNAL(BASE,RETYPE,METHOD_NAME,PARAMS,RETURN) \
165  namespace final_unsuggest { \
166  struct NF_JOIN(BASE,METHOD_NAME) final : BASE { \
167  inline RETYPE METHOD_NAME PARAMS override; \
168  }; \
169  }
170 
171 # endif
172 
173 #else
174 
175 # define PREPARE_MARK_NONFINAL_CLASS(CLASS)
176 # define MARK_NONFINAL_CLASS(BASE)
177 # define MARK_NONFINAL__INTERNAL(BASE,RETURN_TYPE,METHOD_NAME,PARAMS,RETURN)
178 
179 #endif
180 
181 
182 #define MARK_NONFINAL_DTOR(BASE) MARK_NONFINAL_CLASS(BASE)
183 
184 // like MARK_NONFINAL_FUNCTION, but void "result":
185 # define MARK_NONFINAL_FUNCTION(BASE,RETYPE,METHOD_NAME,PARAMS,RETVAL) MARK_NONFINAL__INTERNAL(BASE,RETYPE,METHOD_NAME,PARAMS,return RETVAL)
186 # define MARK_NONFINAL_METHOD(BASE,METHOD_NAME,PARAMS) MARK_NONFINAL__INTERNAL(BASE,void,METHOD_NAME,PARAMS,)
187 
188 
189 #undef ARB_ENABLE11_FEATURES
190 #undef ARB_ENABLE14_FEATURES
191 
192 #else
193 #error cxxforward.h included twice
194 #endif // CXXFORWARD_H