clang-tools 6.0.0

UnusedParametersCheck.cpp
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1 //===--- UnusedParametersCheck.cpp - clang-tidy----------------------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9
10 #include "UnusedParametersCheck.h"
11 #include "clang/AST/ASTContext.h"
12 #include "clang/AST/RecursiveASTVisitor.h"
13 #include "clang/ASTMatchers/ASTMatchFinder.h"
14 #include "clang/Lex/Lexer.h"
15 #include <unordered_set>
16
17 using namespace clang::ast_matchers;
18
19 namespace clang {
20 namespace tidy {
21 namespace misc {
22
23 namespace {
24 bool isOverrideMethod(const FunctionDecl *Function) {
25 if (const auto *MD = dyn_cast<CXXMethodDecl>(Function))
26 return MD->size_overridden_methods() > 0 || MD->hasAttr<OverrideAttr>();
27 return false;
28 }
29 } // namespace
30
31 void UnusedParametersCheck::registerMatchers(MatchFinder *Finder) {
32 Finder->addMatcher(
33 functionDecl(isDefinition(), hasBody(stmt()), hasAnyParameter(decl()))
34 .bind("function"),
35 this);
36 }
37
38 template <typename T>
39 static CharSourceRange removeNode(const MatchFinder::MatchResult &Result,
40 const T *PrevNode, const T *Node,
41 const T *NextNode) {
42 if (NextNode)
43 return CharSourceRange::getCharRange(Node->getLocStart(),
44 NextNode->getLocStart());
45
46 if (PrevNode)
47 return CharSourceRange::getTokenRange(
48 Lexer::getLocForEndOfToken(PrevNode->getLocEnd(), 0,
49 *Result.SourceManager,
50 Result.Context->getLangOpts()),
51 Node->getLocEnd());
52
53 return CharSourceRange::getTokenRange(Node->getSourceRange());
54 }
55
56 static FixItHint removeParameter(const MatchFinder::MatchResult &Result,
57 const FunctionDecl *Function, unsigned Index) {
58 return FixItHint::CreateRemoval(removeNode(
59 Result, Index > 0 ? Function->getParamDecl(Index - 1) : nullptr,
60 Function->getParamDecl(Index),
61 Index + 1 < Function->getNumParams() ? Function->getParamDecl(Index + 1)
62 : nullptr));
63 }
64
65 static FixItHint removeArgument(const MatchFinder::MatchResult &Result,
66 const CallExpr *Call, unsigned Index) {
67 return FixItHint::CreateRemoval(removeNode(
68 Result, Index > 0 ? Call->getArg(Index - 1) : nullptr,
69 Call->getArg(Index),
70 Index + 1 < Call->getNumArgs() ? Call->getArg(Index + 1) : nullptr));
71 }
72
73 class UnusedParametersCheck::IndexerVisitor
74 : public RecursiveASTVisitor<IndexerVisitor> {
75 public:
76 IndexerVisitor(TranslationUnitDecl *Top) { TraverseDecl(Top); }
77
78 const std::unordered_set<const CallExpr *> &
79 getFnCalls(const FunctionDecl *Fn) {
80 return Index[Fn->getCanonicalDecl()].Calls;
81 }
82
83 const std::unordered_set<const DeclRefExpr *> &
84 getOtherRefs(const FunctionDecl *Fn) {
85 return Index[Fn->getCanonicalDecl()].OtherRefs;
86 }
87
88 bool shouldTraversePostOrder() const { return true; }
89
90 bool WalkUpFromDeclRefExpr(DeclRefExpr *DeclRef) {
91 if (const auto *Fn = dyn_cast<FunctionDecl>(DeclRef->getDecl())) {
92 Fn = Fn->getCanonicalDecl();
93 Index[Fn].OtherRefs.insert(DeclRef);
94 }
95 return true;
96 }
97
98 bool WalkUpFromCallExpr(CallExpr *Call) {
99 if (const auto *Fn =
100 dyn_cast_or_null<FunctionDecl>(Call->getCalleeDecl())) {
101 Fn = Fn->getCanonicalDecl();
102 if (const auto *Ref =
103 dyn_cast<DeclRefExpr>(Call->getCallee()->IgnoreImplicit())) {
104 Index[Fn].OtherRefs.erase(Ref);
105 }
106 Index[Fn].Calls.insert(Call);
107 }
108 return true;
109 }
110
111 private:
112 struct IndexEntry {
113 std::unordered_set<const CallExpr *> Calls;
114 std::unordered_set<const DeclRefExpr *> OtherRefs;
115 };
116
117 std::unordered_map<const FunctionDecl *, IndexEntry> Index;
118 };
119
120 UnusedParametersCheck::~UnusedParametersCheck() = default;
121
122 UnusedParametersCheck::UnusedParametersCheck(StringRef Name,
123 ClangTidyContext *Context)
124 : ClangTidyCheck(Name, Context) {}
125
126 void UnusedParametersCheck::warnOnUnusedParameter(
127 const MatchFinder::MatchResult &Result, const FunctionDecl *Function,
128 unsigned ParamIndex) {
129 const auto *Param = Function->getParamDecl(ParamIndex);
130 auto MyDiag = diag(Param->getLocation(), "parameter %0 is unused") << Param;
131
132 if (!Indexer) {
133 Indexer = llvm::make_unique<IndexerVisitor>(
134 Result.Context->getTranslationUnitDecl());
135 }
136
137 // Comment out parameter name for non-local functions.
138 if (Function->isExternallyVisible() ||
139 !Result.SourceManager->isInMainFile(Function->getLocation()) ||
140 !Indexer->getOtherRefs(Function).empty() || isOverrideMethod(Function)) {
141 SourceRange RemovalRange(Param->getLocation());
142 // Note: We always add a space before the '/*' to not accidentally create a
143 // '*/*' for pointer types, which doesn't start a comment. clang-format will
144 // clean this up afterwards.
145 MyDiag << FixItHint::CreateReplacement(
146 RemovalRange, (Twine(" /*") + Param->getName() + "*/").str());
147 return;
148 }
149
150 // Fix all redeclarations.
151 for (const FunctionDecl *FD : Function->redecls())
152 if (FD->param_size())
153 MyDiag << removeParameter(Result, FD, ParamIndex);
154
155 // Fix all call sites.
156 for (const auto *Call : Indexer->getFnCalls(Function))
157 MyDiag << removeArgument(Result, Call, ParamIndex);
158 }
159
160 void UnusedParametersCheck::check(const MatchFinder::MatchResult &Result) {
161 const auto *Function = Result.Nodes.getNodeAs<FunctionDecl>("function");
162 if (!Function->hasWrittenPrototype() || Function->isTemplateInstantiation())
163 return;
164 if (const auto *Method = dyn_cast<CXXMethodDecl>(Function))
165 if (Method->isLambdaStaticInvoker())
166 return;
167 for (unsigned i = 0, e = Function->getNumParams(); i != e; ++i) {
168 const auto *Param = Function->getParamDecl(i);
169 if (Param->isUsed() || Param->isReferenced() || !Param->getDeclName() ||
170 Param->hasAttr<UnusedAttr>())
171 continue;
172 warnOnUnusedParameter(Result, Function, i);
173 }
174 }
175
176 } // namespace misc
177 } // namespace tidy
178 } // namespace clang
clang::ast_matchers
Definition: ClangTidyDiagnosticConsumer.h:27
clang::tidy::bugprone::isOverrideMethod
static bool isOverrideMethod(const CXXMethodDecl *MD)
Finds out if the given method overrides some method.
Definition: VirtualNearMissCheck.cpp:29
Name
StringHandle Name
Definition: PreprocessorTracker.cpp:525
clang::tidy::misc::removeArgument
static FixItHint removeArgument(const MatchFinder::MatchResult &Result, const CallExpr *Call, unsigned Index)
Definition: UnusedParametersCheck.cpp:65
clang::tidy::misc::UnusedParametersCheck::IndexerVisitor::shouldTraversePostOrder
bool shouldTraversePostOrder() const
Definition: UnusedParametersCheck.cpp:88
clang::tidy::misc::UnusedParametersCheck::IndexerVisitor
Definition: UnusedParametersCheck.cpp:73
clang::tidy::ClangTidyCheck
Base class for all clang-tidy checks.
Definition: ClangTidy.h:127
clang::tidy::misc::UnusedParametersCheck::IndexerVisitor::getFnCalls
const std::unordered_set< const CallExpr * > & getFnCalls(const FunctionDecl *Fn)
Definition: UnusedParametersCheck.cpp:79
clang::tidy::misc::UnusedParametersCheck::IndexerVisitor::WalkUpFromDeclRefExpr
bool WalkUpFromDeclRefExpr(DeclRefExpr *DeclRef)
Definition: UnusedParametersCheck.cpp:90
UnusedParametersCheck.h
clang::tidy::misc::UnusedParametersCheck::IndexerVisitor::IndexerVisitor
IndexerVisitor(TranslationUnitDecl *Top)
Definition: UnusedParametersCheck.cpp:76
clang
Definition: AndroidTidyModule.cpp:28
clang::tidy::misc::UnusedParametersCheck::IndexerVisitor::getOtherRefs
const std::unordered_set< const DeclRefExpr * > & getOtherRefs(const FunctionDecl *Fn)
Definition: UnusedParametersCheck.cpp:84
clang::tidy::misc::UnusedParametersCheck::check
void check(const ast_matchers::MatchFinder::MatchResult &Result) override
ClangTidyChecks that register ASTMatchers should do the actual work in here.
Definition: UnusedParametersCheck.cpp:160
clang::tidy::ClangTidyContext
Every ClangTidyCheck reports errors through a DiagnosticsEngine provided by this context.
Definition: ClangTidyDiagnosticConsumer.h:104
clang::tidy::misc::removeNode
static CharSourceRange removeNode(const MatchFinder::MatchResult &Result, const T *PrevNode, const T *Node, const T *NextNode)
Definition: UnusedParametersCheck.cpp:39
clang::tidy::misc::UnusedParametersCheck::IndexerVisitor::WalkUpFromCallExpr
bool WalkUpFromCallExpr(CallExpr *Call)
Definition: UnusedParametersCheck.cpp:98
DeclRef
const DeclRefExpr * DeclRef
Definition: UseAfterMoveCheck.cpp:30
clang::tidy::ClangTidyCheck::diag
DiagnosticBuilder diag(SourceLocation Loc, StringRef Description, DiagnosticIDs::Level Level=DiagnosticIDs::Warning)
Add a diagnostic with the check&#39;s name.
Definition: ClangTidy.cpp:416
clang::tidy::misc::removeParameter
static FixItHint removeParameter(const MatchFinder::MatchResult &Result, const FunctionDecl *Function, unsigned Index)
Definition: UnusedParametersCheck.cpp:56