clang-tools 10.0.0

ExceptionAnalyzer.h
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1 //===--- ExceptionAnalyzer.h - clang-tidy -----------------------*- 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 #ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_UTILS_EXCEPTION_ANALYZER_H
10 #define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_UTILS_EXCEPTION_ANALYZER_H
11
12 #include "clang/AST/ASTContext.h"
13 #include "clang/ASTMatchers/ASTMatchFinder.h"
14 #include "llvm/ADT/SmallSet.h"
15 #include "llvm/ADT/StringSet.h"
16
17 namespace clang {
18 namespace tidy {
19 namespace utils {
20
21 /// This class analysis if a `FunctionDecl` can in principle throw an
22 /// exception, either directly or indirectly. It can be configured to ignore
23 /// custom exception types.
24 class ExceptionAnalyzer {
25 public:
26 enum class State : std::int8_t {
27 Throwing = 0, ///< The function can definitely throw given an AST.
28 NotThrowing = 1, ///< This function can not throw, given an AST.
29 Unknown = 2, ///< This can happen for extern functions without available
30 ///< definition.
31 };
32
33 /// Bundle the gathered information about an entity like a function regarding
34 /// it's exception behaviour. The 'NonThrowing'-state can be considered as the
35 /// neutral element in terms of information propagation.
36 /// In the case of 'Throwing' state it is possible that 'getExceptionTypes'
37 /// does not include *ALL* possible types as there is the possibility that
38 /// an 'Unknown' function is called that might throw a previously unknown
39 /// exception at runtime.
40 class ExceptionInfo {
41 public:
42 using Throwables = llvm::SmallSet<const Type *, 2>;
43 static ExceptionInfo createUnknown() {
44 return ExceptionInfo(State::Unknown);
45 }
46 static ExceptionInfo createNonThrowing() {
47 return ExceptionInfo(State::Throwing);
48 }
49
50 /// By default the exception situation is unknown and must be
51 /// clarified step-wise.
52 ExceptionInfo() : Behaviour(State::NotThrowing), ContainsUnknown(false) {}
53 ExceptionInfo(State S)
54 : Behaviour(S), ContainsUnknown(S == State::Unknown) {}
55
56 ExceptionInfo(const ExceptionInfo &) = default;
57 ExceptionInfo &operator=(const ExceptionInfo &) = default;
58 ExceptionInfo(ExceptionInfo &&) = default;
59 ExceptionInfo &operator=(ExceptionInfo &&) = default;
60
61 State getBehaviour() const { return Behaviour; }
62
63 /// Register a single exception type as recognized potential exception to be
64 /// thrown.
65 void registerException(const Type *ExceptionType);
66
67 /// Registers a `SmallVector` of exception types as recognized potential
68 /// exceptions to be thrown.
69 void registerExceptions(const Throwables &Exceptions);
70
71 /// Updates the local state according to the other state. That means if
72 /// for example a function contains multiple statements the 'ExceptionInfo'
73 /// for the final function is the merged result of each statement.
74 /// If one of these statements throws the whole function throws and if one
75 /// part is unknown and the rest is non-throwing the result will be
76 /// unknown.
77 ExceptionInfo &merge(const ExceptionInfo &Other);
78
79 /// This method is useful in case 'catch' clauses are analyzed as it is
80 /// possible to catch multiple exception types by one 'catch' if they
81 /// are a subclass of the 'catch'ed exception type.
82 /// Returns 'true' if some exceptions were filtered, otherwise 'false'.
83 bool filterByCatch(const Type *BaseClass);
84
85 /// Filter the set of thrown exception type against a set of ignored
86 /// types that shall not be considered in the exception analysis.
87 /// This includes explicit `std::bad_alloc` ignoring as separate option.
88 ExceptionInfo &
89 filterIgnoredExceptions(const llvm::StringSet<> &IgnoredTypes,
90 bool IgnoreBadAlloc);
91
92 /// Clear the state to 'NonThrowing' to make the corresponding entity
93 /// neutral.
94 void clear();
95
96 /// References the set of known exception types that can escape from the
97 /// corresponding entity.
98 const Throwables &getExceptionTypes() const { return ThrownExceptions; }
99
100 /// Signal if the there is any 'Unknown' element within the scope of
101 /// the related entity. This might be relevant if the entity is 'Throwing'
102 /// and to ensure that no other exception then 'getExceptionTypes' can
103 /// occur. If there is an 'Unknown' element this can not be guaranteed.
104 bool containsUnknownElements() const { return ContainsUnknown; }
105
106 private:
107 /// Recalculate the 'Behaviour' for example after filtering.
108 void reevaluateBehaviour();
109
110 /// Keep track if the entity related to this 'ExceptionInfo' can in princple
111 /// throw, if it's unknown or if it won't throw.
112 State Behaviour;
113
114 /// Keep track if the entity contains any unknown elements to keep track
115 /// of the certainty of decisions and/or correct 'Behaviour' transition
116 /// after filtering.
117 bool ContainsUnknown;
118
119 /// 'ThrownException' is empty if the 'Behaviour' is either 'NotThrowing' or
120 /// 'Unknown'.
121 Throwables ThrownExceptions;
122 };
123
124 ExceptionAnalyzer() = default;
125
126 void ignoreBadAlloc(bool ShallIgnore) { IgnoreBadAlloc = ShallIgnore; }
127 void ignoreExceptions(llvm::StringSet<> ExceptionNames) {
128 IgnoredExceptions = std::move(ExceptionNames);
129 }
130
131 ExceptionInfo analyze(const FunctionDecl *Func);
132 ExceptionInfo analyze(const Stmt *Stmt);
133
134 private:
135 ExceptionInfo
136 throwsException(const FunctionDecl *Func,
137 llvm::SmallSet<const FunctionDecl *, 32> &CallStack);
138 ExceptionInfo
139 throwsException(const Stmt *St, const ExceptionInfo::Throwables &Caught,
140 llvm::SmallSet<const FunctionDecl *, 32> &CallStack);
141
142 ExceptionInfo analyzeImpl(const FunctionDecl *Func);
143 ExceptionInfo analyzeImpl(const Stmt *Stmt);
144
145 template <typename T> ExceptionInfo analyzeDispatch(const T *Node);
146
147 bool IgnoreBadAlloc = true;
148 llvm::StringSet<> IgnoredExceptions;
149 std::map<const FunctionDecl *, ExceptionInfo> FunctionCache;
150 };
151
152 } // namespace utils
153 } // namespace tidy
154 } // namespace clang
155
156 #endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_UTILS_EXCEPTION_ANALYZER_H
clang::tidy::utils::ExceptionAnalyzer::ExceptionInfo::Throwables
llvm::SmallSet< const Type *, 2 > Throwables
Definition: ExceptionAnalyzer.h:42
clang::tidy::utils::ExceptionAnalyzer::ExceptionInfo
Bundle the gathered information about an entity like a function regarding it&#39;s exception behaviour...
Definition: ExceptionAnalyzer.h:40
clang::tidy::utils::ExceptionAnalyzer::ExceptionInfo::ExceptionInfo
ExceptionInfo()
By default the exception situation is unknown and must be clarified step-wise.
Definition: ExceptionAnalyzer.h:52
clang::tidy::utils::ExceptionAnalyzer::ExceptionInfo::createNonThrowing
static ExceptionInfo createNonThrowing()
Definition: ExceptionAnalyzer.h:46
clang::tidy::utils::ExceptionAnalyzer::ExceptionInfo::getBehaviour
State getBehaviour() const
Definition: ExceptionAnalyzer.h:61
clang::tidy::utils::ExceptionAnalyzer::State::NotThrowing
This function can not throw, given an AST.
clang::tidy::utils::ExceptionAnalyzer::State
State
Definition: ExceptionAnalyzer.h:26
clang::tidy::utils::ExceptionAnalyzer::State::Unknown
This can happen for extern functions without available definition.
clang::tidy::utils::ExceptionAnalyzer::ExceptionInfo::getExceptionTypes
const Throwables & getExceptionTypes() const
References the set of known exception types that can escape from the corresponding entity...
Definition: ExceptionAnalyzer.h:98
clang::tidy::utils::ExceptionAnalyzer
This class analysis if a FunctionDecl can in principle throw an exception, either directly or indirec...
Definition: ExceptionAnalyzer.h:24
clang::tidy::utils::ExceptionAnalyzer::State::Throwing
The function can definitely throw given an AST.
clang
===– Representation.cpp - ClangDoc Representation --------—*- C++ -*-===//
Definition: ApplyReplacements.h:27
clang::tidy::utils::ExceptionAnalyzer::analyze
ExceptionInfo analyze(const FunctionDecl *Func)
Definition: ExceptionAnalyzer.cpp:250
clang::tidy::utils::ExceptionAnalyzer::ExceptionInfo::containsUnknownElements
bool containsUnknownElements() const
Signal if the there is any &#39;Unknown&#39; element within the scope of the related entity.
Definition: ExceptionAnalyzer.h:104
clang::tidy::utils::ExceptionAnalyzer::ignoreBadAlloc
void ignoreBadAlloc(bool ShallIgnore)
Definition: ExceptionAnalyzer.h:126
clang::tidy::utils::ExceptionAnalyzer::ExceptionInfo::createUnknown
static ExceptionInfo createUnknown()
Definition: ExceptionAnalyzer.h:43
clang::tidy::utils::ExceptionAnalyzer::ExceptionInfo::ExceptionInfo
ExceptionInfo(State S)
Definition: ExceptionAnalyzer.h:53
clang::tidy::utils::ExceptionAnalyzer::ExceptionAnalyzer
ExceptionAnalyzer()=default
Type
NodeType Type
Definition: HTMLGenerator.cpp:73
clang::tidy::utils::ExceptionAnalyzer::ignoreExceptions
void ignoreExceptions(llvm::StringSet<> ExceptionNames)
Definition: ExceptionAnalyzer.h:127