clang-tools 10.0.0

UnusedRaiiCheck.cpp
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1 //===--- UnusedRaiiCheck.cpp - clang-tidy ---------------------------------===//
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 "UnusedRaiiCheck.h"
10 #include "clang/AST/ASTContext.h"
11 #include "clang/Lex/Lexer.h"
12
13 using namespace clang::ast_matchers;
14
15 namespace clang {
16 namespace tidy {
17 namespace bugprone {
18
19 namespace {
20 AST_MATCHER(CXXRecordDecl, hasNonTrivialDestructor) {
21 // TODO: If the dtor is there but empty we don't want to warn either.
22 return Node.hasDefinition() && Node.hasNonTrivialDestructor();
23 }
24 } // namespace
25
26 void UnusedRaiiCheck::registerMatchers(MatchFinder *Finder) {
27 // Only register the matchers for C++; the functionality currently does not
28 // provide any benefit to other languages, despite being benign.
29 if (!getLangOpts().CPlusPlus)
30 return;
31
32 // Look for temporaries that are constructed in-place and immediately
33 // destroyed. Look for temporaries created by a functional cast but not for
34 // those returned from a call.
35 auto BindTemp =
36 cxxBindTemporaryExpr(unless(has(ignoringParenImpCasts(callExpr()))))
37 .bind("temp");
38 Finder->addMatcher(
39 exprWithCleanups(unless(isInTemplateInstantiation()),
40 hasParent(compoundStmt().bind("compound")),
41 hasType(cxxRecordDecl(hasNonTrivialDestructor())),
42 anyOf(has(ignoringParenImpCasts(BindTemp)),
43 has(ignoringParenImpCasts(cxxFunctionalCastExpr(
44 has(ignoringParenImpCasts(BindTemp)))))))
45 .bind("expr"),
46 this);
47 }
48
49 void UnusedRaiiCheck::check(const MatchFinder::MatchResult &Result) {
50 const auto *E = Result.Nodes.getNodeAs<Expr>("expr");
51
52 // We ignore code expanded from macros to reduce the number of false
53 // positives.
54 if (E->getBeginLoc().isMacroID())
55 return;
56
57 // Don't emit a warning for the last statement in the surrounding compund
58 // statement.
59 const auto *CS = Result.Nodes.getNodeAs<CompoundStmt>("compound");
60 if (E == CS->body_back())
61 return;
62
63 // Emit a warning.
64 auto D = diag(E->getBeginLoc(), "object destroyed immediately after "
65 "creation; did you mean to name the object?");
66 const char *Replacement = " give_me_a_name";
67
68 // If this is a default ctor we have to remove the parens or we'll introduce a
69 // most vexing parse.
70 const auto *BTE = Result.Nodes.getNodeAs<CXXBindTemporaryExpr>("temp");
71 if (const auto *TOE = dyn_cast<CXXTemporaryObjectExpr>(BTE->getSubExpr()))
72 if (TOE->getNumArgs() == 0) {
73 D << FixItHint::CreateReplacement(
74 CharSourceRange::getTokenRange(TOE->getParenOrBraceRange()),
75 Replacement);
76 return;
77 }
78
79 // Otherwise just suggest adding a name. To find the place to insert the name
80 // find the first TypeLoc in the children of E, which always points to the
81 // written type.
82 auto Matches =
83 match(expr(hasDescendant(typeLoc().bind("t"))), *E, *Result.Context);
84 const auto *TL = selectFirst<TypeLoc>("t", Matches);
85 D << FixItHint::CreateInsertion(
86 Lexer::getLocForEndOfToken(TL->getEndLoc(), 0, *Result.SourceManager,
87 getLangOpts()),
88 Replacement);
89 }
90
91 } // namespace bugprone
92 } // namespace tidy
93 } // namespace clang
clang::ast_matchers
Definition: AbseilMatcher.h:14
clang::ast_matchers::AST_MATCHER
AST_MATCHER(Expr, isMacroID)
Definition: PreferIsaOrDynCastInConditionalsCheck.cpp:18
UnusedRaiiCheck.h
clang::clangd::match
std::vector< std::string > match(const SymbolIndex &I, const FuzzyFindRequest &Req, bool *Incomplete)
Definition: TestIndex.cpp:94
clang::clangd::getTokenRange
llvm::Optional< Range > getTokenRange(const SourceManager &SM, const LangOptions &LangOpts, SourceLocation TokLoc)
Returns the taken range at TokLoc.
Definition: SourceCode.cpp:227
clang
===– Representation.cpp - ClangDoc Representation --------—*- C++ -*-===//
Definition: ApplyReplacements.h:27
E
const Expr * E
Definition: AvoidBindCheck.cpp:82