1 //===--- NoexceptMoveConstructorCheck.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 "NoexceptMoveConstructorCheck.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 performance {
20 
21 void NoexceptMoveConstructorCheck::registerMatchers(MatchFinder *Finder) {
22   Finder->addMatcher(
23       cxxMethodDecl(anyOf(cxxConstructorDecl(), hasOverloadedOperatorName("=")),
24                     unless(isImplicit()), unless(isDeleted()))
25           .bind("decl"),
26       this);
27 }
28 
29 void NoexceptMoveConstructorCheck::check(
30     const MatchFinder::MatchResult &Result) {
31   if (const auto *Decl = Result.Nodes.getNodeAs<CXXMethodDecl>("decl")) {
32     bool IsConstructor = false;
33     if (const auto *Ctor = dyn_cast<CXXConstructorDecl>(Decl)) {
34       if (!Ctor->isMoveConstructor())
35         return;
36       IsConstructor = true;
37     } else if (!Decl->isMoveAssignmentOperator()) {
38       return;
39     }
40 
41     const auto *ProtoType = Decl->getType()->getAs<FunctionProtoType>();
42 
43     if (isUnresolvedExceptionSpec(ProtoType->getExceptionSpecType()))
44       return;
45 
46     if (!isNoexceptExceptionSpec(ProtoType->getExceptionSpecType())) {
47       auto Diag = diag(Decl->getLocation(),
48                        "move %select{assignment operator|constructor}0s should "
49                        "be marked noexcept")
50                   << IsConstructor;
51       // Add FixIt hints.
52       SourceManager &SM = *Result.SourceManager;
53       assert(Decl->getNumParams() > 0);
54       SourceLocation NoexceptLoc = Decl->getParamDecl(Decl->getNumParams() - 1)
55                                        ->getSourceRange()
56                                        .getEnd();
57       if (NoexceptLoc.isValid())
58         NoexceptLoc = Lexer::findLocationAfterToken(
59             NoexceptLoc, tok::r_paren, SM, Result.Context->getLangOpts(), true);
60       if (NoexceptLoc.isValid())
61         Diag << FixItHint::CreateInsertion(NoexceptLoc, " noexcept ");
62       return;
63     }
64 
65     // Don't complain about nothrow(false), but complain on nothrow(expr)
66     // where expr evaluates to false.
67     if (ProtoType->canThrow() == CT_Can) {
68       Expr *E = ProtoType->getNoexceptExpr();
69       E = E->IgnoreImplicit();
70       if (!isa<CXXBoolLiteralExpr>(E)) {
71         diag(E->getExprLoc(),
72              "noexcept specifier on the move %select{assignment "
73              "operator|constructor}0 evaluates to 'false'")
74             << IsConstructor;
75       }
76     }
77   }
78 }
79 
80 } // namespace performance
81 } // namespace tidy
82 } // namespace clang
83