clang-tools-extra/clang-tidy/bugprone/UndelegatedConstructorCheck.cpp

   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 {
  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.
  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
  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
  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