1 //===--- UndelegatedConstructorCheck.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 "UndelegatedConstructorCheck.h"
10 #include "clang/AST/ASTContext.h"
11 #include "clang/Lex/Lexer.h"
12
13 using namespace clang::ast_matchers;
14
15 namespace clang::tidy::bugprone {
16
17 namespace {
AST_MATCHER_P(Stmt,ignoringTemporaryExpr,ast_matchers::internal::Matcher<Stmt>,InnerMatcher)18 AST_MATCHER_P(Stmt, ignoringTemporaryExpr,
19 ast_matchers::internal::Matcher<Stmt>, InnerMatcher) {
20 const Stmt *E = &Node;
21 for (;;) {
22 // Temporaries with non-trivial dtors.
23 if (const auto *EWC = dyn_cast<ExprWithCleanups>(E))
24 E = EWC->getSubExpr();
25 // Temporaries with zero or more than two ctor arguments.
26 else if (const auto *BTE = dyn_cast<CXXBindTemporaryExpr>(E))
27 E = BTE->getSubExpr();
28 // Temporaries with exactly one ctor argument.
29 else if (const auto *FCE = dyn_cast<CXXFunctionalCastExpr>(E))
30 E = FCE->getSubExpr();
31 else
32 break;
33 }
34
35 return InnerMatcher.matches(*E, Finder, Builder);
36 }
37
38 // Finds a node if it's a base of an already bound node.
AST_MATCHER_P(CXXRecordDecl,baseOfBoundNode,std::string,ID)39 AST_MATCHER_P(CXXRecordDecl, baseOfBoundNode, std::string, ID) {
40 return Builder->removeBindings(
41 [&](const ast_matchers::internal::BoundNodesMap &Nodes) {
42 const auto *Derived = Nodes.getNodeAs<CXXRecordDecl>(ID);
43 return Derived != &Node && !Derived->isDerivedFrom(&Node);
44 });
45 }
46 } // namespace
47
registerMatchers(MatchFinder * Finder)48 void UndelegatedConstructorCheck::registerMatchers(MatchFinder *Finder) {
49 // We look for calls to constructors of the same type in constructors. To do
50 // this we have to look through a variety of nodes that occur in the path,
51 // depending on the type's destructor and the number of arguments on the
52 // constructor call, this is handled by ignoringTemporaryExpr. Ignore template
53 // instantiations to reduce the number of duplicated warnings.
54
55 Finder->addMatcher(
56 traverse(
57 TK_AsIs,
58 compoundStmt(hasParent(cxxConstructorDecl(
59 ofClass(cxxRecordDecl().bind("parent")))),
60 forEach(ignoringTemporaryExpr(
61 cxxConstructExpr(
62 hasDeclaration(cxxConstructorDecl(ofClass(
63 cxxRecordDecl(baseOfBoundNode("parent"))))))
64 .bind("construct"))),
65 unless(isInTemplateInstantiation()))),
66 this);
67 }
68
check(const MatchFinder::MatchResult & Result)69 void UndelegatedConstructorCheck::check(
70 const MatchFinder::MatchResult &Result) {
71 const auto *E = Result.Nodes.getNodeAs<CXXConstructExpr>("construct");
72 diag(E->getBeginLoc(), "did you intend to call a delegated constructor? "
73 "A temporary object is created here instead");
74 }
75
76 } // namespace clang::tidy::bugprone
77