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14 | pmbaty | 1 | //===--- MSVCErrorWorkarounds.h - Enable future<Error> in MSVC --*- C++ -*-===// |
2 | // |
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3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
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4 | // See https://llvm.org/LICENSE.txt for license information. |
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5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
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6 | // |
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7 | //===----------------------------------------------------------------------===// |
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8 | // |
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9 | // MSVC's promise/future implementation requires types to be default |
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10 | // constructible, so this header provides analogues of Error an Expected |
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11 | // that are default constructed in a safely destructible state. |
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12 | // |
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13 | // FIXME: Kill off this header and migrate all users to Error/Expected once we |
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14 | // move to MSVC versions that support non-default-constructible types. |
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15 | // |
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16 | //===----------------------------------------------------------------------===// |
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17 | |||
18 | #ifndef LLVM_SUPPORT_MSVCERRORWORKAROUNDS_H |
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19 | #define LLVM_SUPPORT_MSVCERRORWORKAROUNDS_H |
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20 | |||
21 | #include "llvm/Support/Error.h" |
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22 | |||
23 | namespace llvm { |
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24 | |||
25 | // A default-constructible llvm::Error that is suitable for use with MSVC's |
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26 | // std::future implementation which requires default constructible types. |
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27 | class MSVCPError : public Error { |
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28 | public: |
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29 | MSVCPError() { (void)!!*this; } |
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30 | |||
31 | MSVCPError(MSVCPError &&Other) : Error(std::move(Other)) {} |
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32 | |||
33 | MSVCPError &operator=(MSVCPError Other) { |
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34 | Error::operator=(std::move(Other)); |
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35 | return *this; |
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36 | } |
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37 | |||
38 | MSVCPError(Error Err) : Error(std::move(Err)) {} |
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39 | }; |
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40 | |||
41 | // A default-constructible llvm::Expected that is suitable for use with MSVC's |
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42 | // std::future implementation, which requires default constructible types. |
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43 | template <typename T> class MSVCPExpected : public Expected<T> { |
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44 | public: |
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45 | MSVCPExpected() |
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46 | : Expected<T>(make_error<StringError>("", inconvertibleErrorCode())) { |
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47 | consumeError(this->takeError()); |
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48 | } |
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49 | |||
50 | MSVCPExpected(MSVCPExpected &&Other) : Expected<T>(std::move(Other)) {} |
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51 | |||
52 | MSVCPExpected &operator=(MSVCPExpected &&Other) { |
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53 | Expected<T>::operator=(std::move(Other)); |
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54 | return *this; |
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55 | } |
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56 | |||
57 | MSVCPExpected(Error Err) : Expected<T>(std::move(Err)) {} |
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58 | |||
59 | template <typename OtherT> |
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60 | MSVCPExpected( |
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61 | OtherT &&Val, |
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62 | std::enable_if_t<std::is_convertible<OtherT, T>::value> * = nullptr) |
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63 | : Expected<T>(std::move(Val)) {} |
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64 | |||
65 | template <class OtherT> |
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66 | MSVCPExpected( |
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67 | Expected<OtherT> &&Other, |
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68 | std::enable_if_t<std::is_convertible<OtherT, T>::value> * = nullptr) |
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69 | : Expected<T>(std::move(Other)) {} |
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70 | |||
71 | template <class OtherT> |
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72 | explicit MSVCPExpected( |
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73 | Expected<OtherT> &&Other, |
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74 | std::enable_if_t<!std::is_convertible<OtherT, T>::value> * = nullptr) |
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75 | : Expected<T>(std::move(Other)) {} |
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76 | }; |
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77 | |||
78 | } // end namespace llvm |
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79 | |||
80 | #endif // LLVM_SUPPORT_MSVCERRORWORKAROUNDS_H |