1//===- CalledOnceCheck.h - Check 'called once' parameters -------*- 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// This file defines a check for function-like parameters that should be
10// called exactly one time.
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_CLANG_ANALYSIS_ANALYSES_CALLEDONCECHECK_H
15#define LLVM_CLANG_ANALYSIS_ANALYSES_CALLEDONCECHECK_H
16
17namespace clang {
18
19class AnalysisDeclContext;
20class BlockDecl;
21class CFG;
22class Decl;
23class Expr;
24class ParmVarDecl;
25class Stmt;
26
27/// Classification of situations when parameter is not called on every path.
28/// \enum IfThen -- then branch of the if statement has no call.
29/// \enum IfElse -- else branch of the if statement has no call.
30/// \enum Switch -- one of the switch cases doesn't have a call.
31/// \enum SwitchSkipped -- there is no call if none of the cases applies.
32/// \enum LoopEntered -- no call when the loop is entered.
33/// \enum LoopSkipped -- no call when the loop is not entered.
34/// \enum FallbackReason -- fallback case when we were not able to figure out
35/// the reason.
36enum class NeverCalledReason {
37 IfThen,
38 IfElse,
39 Switch,
40 SwitchSkipped,
41 LoopEntered,
42 LoopSkipped,
43 FallbackReason,
44 LARGEST_VALUE = FallbackReason
45};
46
47class CalledOnceCheckHandler {
48public:
49 CalledOnceCheckHandler() = default;
50 virtual ~CalledOnceCheckHandler() = default;
51
52 /// Called when parameter is called twice.
53 /// \param Parameter -- parameter that should be called once.
54 /// \param Call -- call to report the warning.
55 /// \param PrevCall -- previous call.
56 /// \param IsCompletionHandler -- true, if parameter is a completion handler.
57 /// \param Poised -- true, if the second call is guaranteed to happen after
58 /// the first call.
59 virtual void handleDoubleCall(const ParmVarDecl *Parameter, const Expr *Call,
60 const Expr *PrevCall, bool IsCompletionHandler,
61 bool Poised) {}
62
63 /// Called when parameter is not called at all.
64 /// \param Parameter -- parameter that should be called once.
65 /// \param IsCompletionHandler -- true, if parameter is a completion handler.
66 virtual void handleNeverCalled(const ParmVarDecl *Parameter,
67 bool IsCompletionHandler) {}
68
69 /// Called when captured parameter is not called at all.
70 /// \param Parameter -- parameter that should be called once.
71 /// \param Where -- declaration that captures \p Parameter
72 /// \param IsCompletionHandler -- true, if parameter is a completion handler.
73 virtual void handleCapturedNeverCalled(const ParmVarDecl *Parameter,
74 const Decl *Where,
75 bool IsCompletionHandler) {}
76
77 /// Called when parameter is not called on one of the paths.
78 /// Usually we try to find a statement that is the least common ancestor of
79 /// the path containing the call and not containing the call. This helps us
80 /// to pinpoint a bad path for the user.
81 /// \param Parameter -- parameter that should be called once.
82 /// \param Function -- function declaration where the problem occurred.
83 /// \param Where -- the least common ancestor statement.
84 /// \param Reason -- a reason describing the path without a call.
85 /// \param IsCalledDirectly -- true, if parameter actually gets called on
86 /// the other path. It is opposed to be used in some other way (added to some
87 /// collection, passed as a parameter, etc.).
88 /// \param IsCompletionHandler -- true, if parameter is a completion handler.
89 virtual void handleNeverCalled(const ParmVarDecl *Parameter,
90 const Decl *Function, const Stmt *Where,
91 NeverCalledReason Reason,
92 bool IsCalledDirectly,
93 bool IsCompletionHandler) {}
94
95 /// Called when the block is guaranteed to be called exactly once.
96 /// It means that we can be stricter with what we report on that block.
97 /// \param Block -- block declaration that is known to be called exactly once.
98 virtual void
99 handleBlockThatIsGuaranteedToBeCalledOnce(const BlockDecl *Block) {}
100
101 /// Called when the block has no guarantees about how many times it can get
102 /// called.
103 /// It means that we should be more lenient with reporting warnings in it.
104 /// \param Block -- block declaration in question.
105 virtual void handleBlockWithNoGuarantees(const BlockDecl *Block) {}
106};
107
108/// Check given CFG for 'called once' parameter violations.
109///
110/// It traverses the function and tracks how such parameters are used.
111/// It detects two main violations:
112/// * parameter is called twice
113/// * parameter is not called
114///
115/// \param AC -- context.
116/// \param Handler -- a handler for found violations.
117/// \param CheckConventionalParameters -- true, if we want to check parameters
118/// not explicitly marked as 'called once', but having the same requirements
119/// according to conventions.
120void checkCalledOnceParameters(AnalysisDeclContext &AC,
121 CalledOnceCheckHandler &Handler,
122 bool CheckConventionalParameters);
123
124} // end namespace clang
125
126#endif /* LLVM_CLANG_ANALYSIS_ANALYSES_CALLEDONCECHECK_H */
127

source code of clang/include/clang/Analysis/Analyses/CalledOnceCheck.h