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
registerMatchers(MatchFinder * Finder)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 isInTemplateInstantiation())))
28 .bind("ctor");
29
30 auto CtorAsArgument = materializeTemporaryExpr(anyOf(
31 has(ConstructExpr), has(cxxFunctionalCastExpr(has(ConstructExpr)))));
32
33 Finder->addMatcher(
34 traverse(ast_type_traits::TK_AsIs,
35 functionDecl(
36 isDefinition(), // Declarations don't have return statements.
37 returns(unless(anyOf(builtinType(), autoType()))),
38 hasDescendant(returnStmt(hasReturnValue(
39 has(cxxConstructExpr(has(CtorAsArgument)))))))
40 .bind("fn")),
41 this);
42 }
43
check(const MatchFinder::MatchResult & Result)44 void ReturnBracedInitListCheck::check(const MatchFinder::MatchResult &Result) {
45 const auto *MatchedFunctionDecl = Result.Nodes.getNodeAs<FunctionDecl>("fn");
46 const auto *MatchedConstructExpr =
47 Result.Nodes.getNodeAs<CXXConstructExpr>("ctor");
48
49 // Don't make replacements in macro.
50 SourceLocation Loc = MatchedConstructExpr->getExprLoc();
51 if (Loc.isMacroID())
52 return;
53
54 // Make sure that the return type matches the constructed type.
55 const QualType ReturnType =
56 MatchedFunctionDecl->getReturnType().getCanonicalType();
57 const QualType ConstructType =
58 MatchedConstructExpr->getType().getCanonicalType();
59 if (ReturnType != ConstructType)
60 return;
61
62 auto Diag = diag(Loc, "avoid repeating the return type from the "
63 "declaration; use a braced initializer list instead");
64
65 const SourceRange CallParensRange =
66 MatchedConstructExpr->getParenOrBraceRange();
67
68 // Make sure there is an explicit constructor call.
69 if (CallParensRange.isInvalid())
70 return;
71
72 // Make sure that the ctor arguments match the declaration.
73 for (unsigned I = 0, NumParams = MatchedConstructExpr->getNumArgs();
74 I < NumParams; ++I) {
75 if (const auto *VD = dyn_cast<VarDecl>(
76 MatchedConstructExpr->getConstructor()->getParamDecl(I))) {
77 if (MatchedConstructExpr->getArg(I)->getType().getCanonicalType() !=
78 VD->getType().getCanonicalType())
79 return;
80 }
81 }
82
83 // Range for constructor name and opening brace.
84 CharSourceRange CtorCallSourceRange = CharSourceRange::getTokenRange(
85 Loc, CallParensRange.getBegin().getLocWithOffset(-1));
86
87 Diag << FixItHint::CreateRemoval(CtorCallSourceRange)
88 << FixItHint::CreateReplacement(CallParensRange.getBegin(), "{")
89 << FixItHint::CreateReplacement(CallParensRange.getEnd(), "}");
90 }
91
92 } // namespace modernize
93 } // namespace tidy
94 } // namespace clang
95