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