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1 // RUN: %clang_cc1 -verify -std=c++2a -fsyntax-only -triple x86_64-apple-macosx10.14.0 %s
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2 // RUN: %clang_cc1 -verify -std=c++2a -fsyntax-only -triple x86_64-apple-macosx10.14.0 %s -fno-signed-char
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3
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4 #if !__has_builtin(__builtin_bit_cast)
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5 #error
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6 #endif
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7
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8 template <class T, T v>
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9 T instantiate() {
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10 return __builtin_bit_cast(T, v);
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11 }
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12
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13 int x = instantiate<int, 32>();
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14
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15 struct secret_ctor {
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16 char member;
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17
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18 private: secret_ctor() = default;
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19 };
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20
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21 void test1() {
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22 secret_ctor c = __builtin_bit_cast(secret_ctor, (char)0);
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23 }
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24
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25 void test2() {
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26 constexpr int i = 0;
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27 // expected-error@+1{{__builtin_bit_cast source size does not equal destination size (4 vs 1)}}
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28 constexpr char c = __builtin_bit_cast(char, i);
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29 }
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30
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31 struct not_trivially_copyable {
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32 virtual void foo() {}
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33 };
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34
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35 // expected-error@+1{{__builtin_bit_cast source type must be trivially copyable}}
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36 constexpr unsigned long ul = __builtin_bit_cast(unsigned long, not_trivially_copyable{});
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37
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38 // expected-error@+1 {{__builtin_bit_cast destination type must be trivially copyable}}
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39 constexpr long us = __builtin_bit_cast(unsigned long &, 0L);
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40
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41 namespace PR42936 {
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42 template <class T> struct S { int m; };
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43
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44 extern S<int> extern_decl;
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45
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46 int x = __builtin_bit_cast(int, extern_decl);
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47 S<char> y = __builtin_bit_cast(S<char>, 0);
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48 }
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