1 | //===--- MSVCErrorWorkarounds.h - Enable future<Error> in MSVC --*- C++ -*-===// |
2 | // |
3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
4 | // See https://llvm.org/LICENSE.txt for license information. |
5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
6 | // |
7 | //===----------------------------------------------------------------------===// |
8 | // |
9 | // MSVC's promise/future implementation requires types to be default |
10 | // constructible, so this header provides analogues of Error an Expected |
11 | // that are default constructed in a safely destructible state. |
12 | // |
13 | // FIXME: Kill off this header and migrate all users to Error/Expected once we |
14 | // move to MSVC versions that support non-default-constructible types. |
15 | // |
16 | //===----------------------------------------------------------------------===// |
17 | |
18 | #ifndef LLVM_SUPPORT_MSVCERRORWORKAROUNDS_H |
19 | #define LLVM_SUPPORT_MSVCERRORWORKAROUNDS_H |
20 | |
21 | #include "llvm/Support/Error.h" |
22 | |
23 | namespace llvm { |
24 | |
25 | // A default-constructible llvm::Error that is suitable for use with MSVC's |
26 | // std::future implementation which requires default constructible types. |
27 | class MSVCPError : public Error { |
28 | public: |
29 | MSVCPError() { (void)!!*this; } |
30 | |
31 | MSVCPError(MSVCPError &&Other) : Error(std::move(Other)) {} |
32 | |
33 | MSVCPError &operator=(MSVCPError Other) { |
34 | Error::operator=(Other: std::move(Other)); |
35 | return *this; |
36 | } |
37 | |
38 | MSVCPError(Error Err) : Error(std::move(Err)) {} |
39 | }; |
40 | |
41 | // A default-constructible llvm::Expected that is suitable for use with MSVC's |
42 | // std::future implementation, which requires default constructible types. |
43 | template <typename T> class MSVCPExpected : public Expected<T> { |
44 | public: |
45 | MSVCPExpected() |
46 | : Expected<T>(make_error<StringError>(Args: "" , Args: inconvertibleErrorCode())) { |
47 | consumeError(this->takeError()); |
48 | } |
49 | |
50 | MSVCPExpected(MSVCPExpected &&Other) : Expected<T>(std::move(Other)) {} |
51 | |
52 | MSVCPExpected &operator=(MSVCPExpected &&Other) { |
53 | Expected<T>::operator=(std::move(Other)); |
54 | return *this; |
55 | } |
56 | |
57 | MSVCPExpected(Error Err) : Expected<T>(std::move(Err)) {} |
58 | |
59 | template <typename OtherT> |
60 | MSVCPExpected( |
61 | OtherT &&Val, |
62 | std::enable_if_t<std::is_convertible<OtherT, T>::value> * = nullptr) |
63 | : Expected<T>(std::move(Val)) {} |
64 | |
65 | template <class OtherT> |
66 | MSVCPExpected( |
67 | Expected<OtherT> &&Other, |
68 | std::enable_if_t<std::is_convertible<OtherT, T>::value> * = nullptr) |
69 | : Expected<T>(std::move(Other)) {} |
70 | |
71 | template <class OtherT> |
72 | explicit MSVCPExpected( |
73 | Expected<OtherT> &&Other, |
74 | std::enable_if_t<!std::is_convertible<OtherT, T>::value> * = nullptr) |
75 | : Expected<T>(std::move(Other)) {} |
76 | }; |
77 | |
78 | } // end namespace llvm |
79 | |
80 | #endif // LLVM_SUPPORT_MSVCERRORWORKAROUNDS_H |
81 | |