clang-tools-extra/clang-tidy/modernize/ReturnBracedInitListCheck.cpp

   1 //===--- ReturnBracedInitListCheck.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 "ReturnBracedInitListCheck.h"
  10 #include "clang/AST/ASTContext.h"
  11 #include "clang/ASTMatchers/ASTMatchFinder.h"
  12 #include "clang/ASTMatchers/ASTMatchers.h"
  13 #include "clang/Lex/Lexer.h"
  14 #include "clang/Tooling/FixIt.h"
  15
  16 using namespace clang::ast_matchers;
  17
  18 namespace clang::tidy::modernize {
  19
  20 void ReturnBracedInitListCheck::registerMatchers(MatchFinder *Finder) {
  21   auto SemanticallyDifferentContainer = allOf(
  22       hasDeclaration(
  23           // Container(size_type count, const T &value,
  24           //           const Allocator &alloc = Allocator());
  25           cxxConstructorDecl(parameterCountIs(3),
  26                              hasParameter(0, hasType(qualType(hasCanonicalType(
  27                                                  isInteger())))))),
  28       hasType(cxxRecordDecl(hasAnyName("::std::basic_string", "::std::vector",
  29                                        "::std::deque", "::std::forward_list",
  30                                        "::std::list"))));
  31
  32   auto ConstructExpr =
  33       cxxConstructExpr(
  34           unless(anyOf(
  35               // Skip explicit constructor.
  36               hasDeclaration(cxxConstructorDecl(isExplicit())),
  37               // Skip list initialization and constructors with an initializer
  38               // list.
  39               isListInitialization(), hasDescendant(initListExpr()),
  40               // Skip container `vector(size_type, const T&, ...)`.
  41               SemanticallyDifferentContainer)))
  42           .bind("ctor");
  43
  44   Finder->addMatcher(
  45       returnStmt(hasReturnValue(ConstructExpr),
  46                  forFunction(functionDecl(returns(unless(anyOf(builtinType(),
  47                                                                autoType()))))
  48                                  .bind("fn"))),
  49       this);
  50 }
  51
  52 void ReturnBracedInitListCheck::check(const MatchFinder::MatchResult &Result) {
  53   const auto *MatchedFunctionDecl = Result.Nodes.getNodeAs<FunctionDecl>("fn");
  54   const auto *MatchedConstructExpr =
  55       Result.Nodes.getNodeAs<CXXConstructExpr>("ctor");
  56
  57   // Don't make replacements in macro.
  58   SourceLocation Loc = MatchedConstructExpr->getExprLoc();
  59   if (Loc.isMacroID())
  60     return;
  61
  62   // Make sure that the return type matches the constructed type.
  63   const QualType ReturnType =
  64       MatchedFunctionDecl->getReturnType().getCanonicalType();
  65   const QualType ConstructType =
  66       MatchedConstructExpr->getType().getCanonicalType();
  67   if (ReturnType != ConstructType)
  68     return;
  69
  70   auto Diag = diag(Loc, "avoid repeating the return type from the "
  71                         "declaration; use a braced initializer list instead");
  72
  73   const SourceRange CallParensRange =
  74       MatchedConstructExpr->getParenOrBraceRange();
  75
  76   // Make sure there is an explicit constructor call.
  77   if (CallParensRange.isInvalid())
  78     return;
  79
  80   // Make sure that the ctor arguments match the declaration.
  81   for (unsigned I = 0, NumParams = MatchedConstructExpr->getNumArgs();
  82        I < NumParams; ++I) {
  83     if (const auto *VD = dyn_cast<VarDecl>(
  84             MatchedConstructExpr->getConstructor()->getParamDecl(I))) {
  85       if (MatchedConstructExpr->getArg(I)->getType().getCanonicalType() !=
  86           VD->getType().getCanonicalType())
  87         return;
  88     }
  89   }
  90
  91   // Range for constructor name and opening brace.
  92   CharSourceRange CtorCallSourceRange = CharSourceRange::getTokenRange(
  93       Loc, CallParensRange.getBegin().getLocWithOffset(-1));
  94
  95   Diag << FixItHint::CreateRemoval(CtorCallSourceRange)
  96        << FixItHint::CreateReplacement(CallParensRange.getBegin(), "{")
  97        << FixItHint::CreateReplacement(CallParensRange.getEnd(), "}");
  98 }
  99
 100 } // namespace clang::tidy::modernize