1 //===- OptionalDiagnostic.h - An optional diagnostic ------------*- 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 /// \file
10 /// Implements a partial diagnostic which may not be emitted.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #ifndef LLVM_CLANG_AST_OPTIONALDIAGNOSTIC_H
15 #define LLVM_CLANG_AST_OPTIONALDIAGNOSTIC_H
16 
17 #include "clang/AST/APValue.h"
18 #include "clang/Basic/PartialDiagnostic.h"
19 #include "llvm/ADT/APFloat.h"
20 #include "llvm/ADT/APSInt.h"
21 #include "llvm/ADT/SmallVector.h"
22 #include "llvm/ADT/StringRef.h"
23 
24 namespace clang {
25 
26 /// A partial diagnostic which we might know in advance that we are not going
27 /// to emit.
28 class OptionalDiagnostic {
29   PartialDiagnostic *Diag;
30 
31 public:
Diag(Diag)32   explicit OptionalDiagnostic(PartialDiagnostic *Diag = nullptr) : Diag(Diag) {}
33 
34   template <typename T> OptionalDiagnostic &operator<<(const T &v) {
35     if (Diag)
36       *Diag << v;
37     return *this;
38   }
39 
40   OptionalDiagnostic &operator<<(const llvm::APSInt &I) {
41     if (Diag) {
42       SmallVector<char, 32> Buffer;
43       I.toString(Buffer);
44       *Diag << StringRef(Buffer.data(), Buffer.size());
45     }
46     return *this;
47   }
48 
49   OptionalDiagnostic &operator<<(const llvm::APFloat &F) {
50     if (Diag) {
51       // FIXME: Force the precision of the source value down so we don't
52       // print digits which are usually useless (we don't really care here if
53       // we truncate a digit by accident in edge cases).  Ideally,
54       // APFloat::toString would automatically print the shortest
55       // representation which rounds to the correct value, but it's a bit
56       // tricky to implement. Could use std::to_chars.
57       unsigned precision = llvm::APFloat::semanticsPrecision(F.getSemantics());
58       precision = (precision * 59 + 195) / 196;
59       SmallVector<char, 32> Buffer;
60       F.toString(Buffer, precision);
61       *Diag << StringRef(Buffer.data(), Buffer.size());
62     }
63     return *this;
64   }
65 
66   OptionalDiagnostic &operator<<(const llvm::APFixedPoint &FX) {
67     if (Diag) {
68       SmallVector<char, 32> Buffer;
69       FX.toString(Buffer);
70       *Diag << StringRef(Buffer.data(), Buffer.size());
71     }
72     return *this;
73   }
74 };
75 
76 } // namespace clang
77 
78 #endif
79