1 //===--- ExpectedTypes.cpp ---------------------------------------*- 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 #include "ExpectedTypes.h"
10 #include "clang/AST/ASTContext.h"
11 #include "clang/AST/DeclTemplate.h"
12 #include "clang/AST/Type.h"
13 #include "clang/Index/USRGeneration.h"
14 #include "clang/Sema/CodeCompleteConsumer.h"
15 #include "llvm/ADT/None.h"
16 
17 namespace clang {
18 namespace clangd {
19 namespace {
20 
21 static const Type *toEquivClass(ASTContext &Ctx, QualType T) {
22   if (T.isNull() || T->isDependentType())
23     return nullptr;
24   // Drop references, we do not handle reference inits properly anyway.
25   T = T.getCanonicalType().getNonReferenceType();
26   // Numeric types are the simplest case.
27   if (T->isBooleanType())
28     return Ctx.BoolTy.getTypePtr();
29   if (T->isIntegerType() && !T->isEnumeralType())
30     return Ctx.IntTy.getTypePtr(); // All integers are equivalent.
31   if (T->isFloatingType() && !T->isComplexType())
32     return Ctx.FloatTy.getTypePtr(); // All floats are equivalent.
33 
34   // Do some simple transformations.
35   if (T->isArrayType()) // Decay arrays to pointers.
36     return Ctx.getPointerType(QualType(T->getArrayElementTypeNoTypeQual(), 0))
37         .getTypePtr();
38   // Drop the qualifiers and return the resulting type.
39   // FIXME: also drop qualifiers from pointer types, e.g. 'const T* => T*'
40   return T.getTypePtr();
41 }
42 
43 static llvm::Optional<QualType>
44 typeOfCompletion(const CodeCompletionResult &R) {
45   const NamedDecl *D = R.Declaration;
46   // Templates do not have a type on their own, look at the templated decl.
47   if (auto *Template = dyn_cast_or_null<TemplateDecl>(D))
48     D = Template->getTemplatedDecl();
49   auto *VD = dyn_cast_or_null<ValueDecl>(D);
50   if (!VD)
51     return llvm::None; // We handle only variables and functions below.
52   auto T = VD->getType();
53   if (T.isNull())
54     return llvm::None;
55   if (auto *FuncT = T->getAs<FunctionType>()) {
56     // Functions are a special case. They are completed as 'foo()' and we want
57     // to match their return type rather than the function type itself.
58     // FIXME(ibiryukov): in some cases, we might want to avoid completing `()`
59     // after the function name, e.g. `std::cout << std::endl`.
60     return FuncT->getReturnType();
61   }
62   return T;
63 }
64 } // namespace
65 
66 llvm::Optional<OpaqueType> OpaqueType::encode(ASTContext &Ctx, QualType T) {
67   if (T.isNull())
68     return None;
69   const Type *C = toEquivClass(Ctx, T);
70   if (!C)
71     return None;
72   llvm::SmallString<128> Encoded;
73   if (index::generateUSRForType(QualType(C, 0), Ctx, Encoded))
74     return None;
75   return OpaqueType(std::string(Encoded.str()));
76 }
77 
78 OpaqueType::OpaqueType(std::string Data) : Data(std::move(Data)) {}
79 
80 llvm::Optional<OpaqueType> OpaqueType::fromType(ASTContext &Ctx,
81                                                 QualType Type) {
82   return encode(Ctx, Type);
83 }
84 
85 llvm::Optional<OpaqueType>
86 OpaqueType::fromCompletionResult(ASTContext &Ctx,
87                                  const CodeCompletionResult &R) {
88   auto T = typeOfCompletion(R);
89   if (!T)
90     return None;
91   return encode(Ctx, *T);
92 }
93 
94 } // namespace clangd
95 } // namespace clang
96