1 //===--- NoexceptMoveConstructorCheck.cpp - clang-tidy---------------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #include "NoexceptMoveConstructorCheck.h"
11 #include "clang/AST/ASTContext.h"
12 #include "clang/ASTMatchers/ASTMatchFinder.h"
13 
14 using namespace clang::ast_matchers;
15 
16 namespace clang {
17 namespace tidy {
18 namespace performance {
19 
20 void NoexceptMoveConstructorCheck::registerMatchers(MatchFinder *Finder) {
21   // Only register the matchers for C++11; the functionality currently does not
22   // provide any benefit to other languages, despite being benign.
23   if (!getLangOpts().CPlusPlus11)
24     return;
25 
26   Finder->addMatcher(
27       cxxMethodDecl(anyOf(cxxConstructorDecl(), hasOverloadedOperatorName("=")),
28                     unless(isImplicit()), unless(isDeleted()))
29           .bind("decl"),
30       this);
31 }
32 
33 void NoexceptMoveConstructorCheck::check(
34     const MatchFinder::MatchResult &Result) {
35   if (const auto *Decl = Result.Nodes.getNodeAs<CXXMethodDecl>("decl")) {
36     StringRef MethodType = "assignment operator";
37     if (const auto *Ctor = dyn_cast<CXXConstructorDecl>(Decl)) {
38       if (!Ctor->isMoveConstructor())
39         return;
40       MethodType = "constructor";
41     } else if (!Decl->isMoveAssignmentOperator()) {
42       return;
43     }
44 
45     const auto *ProtoType = Decl->getType()->getAs<FunctionProtoType>();
46 
47     if (isUnresolvedExceptionSpec(ProtoType->getExceptionSpecType()))
48       return;
49 
50     switch (ProtoType->getNoexceptSpec(*Result.Context)) {
51     case FunctionProtoType::NR_NoNoexcept:
52       diag(Decl->getLocation(), "move %0s should be marked noexcept")
53           << MethodType;
54       // FIXME: Add a fixit.
55       break;
56     case FunctionProtoType::NR_Throw:
57       // Don't complain about nothrow(false), but complain on nothrow(expr)
58       // where expr evaluates to false.
59       if (const Expr *E = ProtoType->getNoexceptExpr()) {
60         if (isa<CXXBoolLiteralExpr>(E))
61           break;
62         diag(E->getExprLoc(),
63              "noexcept specifier on the move %0 evaluates to 'false'")
64             << MethodType;
65       }
66       break;
67     case FunctionProtoType::NR_Nothrow:
68     case FunctionProtoType::NR_Dependent:
69     case FunctionProtoType::NR_BadNoexcept:
70       break;
71     }
72   }
73 }
74 
75 } // namespace performance
76 } // namespace tidy
77 } // namespace clang
78