1//===--- MisleadingCaptureDefaultByValueCheck.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 "MisleadingCaptureDefaultByValueCheck.h"
10#include "../utils/LexerUtils.h"
11#include "clang/AST/ASTContext.h"
12#include "clang/ASTMatchers/ASTMatchFinder.h"
13#include "llvm/Support/raw_ostream.h"
14
15#include <algorithm>
16
17using namespace clang::ast_matchers;
18
19namespace clang::tidy::cppcoreguidelines {
20
21MisleadingCaptureDefaultByValueCheck::MisleadingCaptureDefaultByValueCheck(
22 StringRef Name, ClangTidyContext *Context)
23 : ClangTidyCheck(Name, Context) {}
24
25void MisleadingCaptureDefaultByValueCheck::registerMatchers(
26 MatchFinder *Finder) {
27 Finder->addMatcher(NodeMatch: lambdaExpr(hasAnyCapture(InnerMatcher: capturesThis())).bind(ID: "lambda"),
28 Action: this);
29}
30
31static SourceLocation findDefaultCaptureEnd(const LambdaExpr *Lambda,
32 ASTContext &Context) {
33 for (const LambdaCapture &Capture : Lambda->explicit_captures()) {
34 if (Capture.isExplicit()) {
35 if (Capture.getCaptureKind() == LCK_ByRef) {
36 const SourceManager &SourceMgr = Context.getSourceManager();
37 SourceLocation AddressofLoc = utils::lexer::findPreviousTokenKind(
38 Start: Capture.getLocation(), SM: SourceMgr, LangOpts: Context.getLangOpts(), TK: tok::amp);
39 return AddressofLoc;
40 }
41 return Capture.getLocation();
42 }
43 }
44 return Lambda->getIntroducerRange().getEnd();
45}
46
47static std::string createReplacementText(const LambdaExpr *Lambda) {
48 std::string Replacement;
49 llvm::raw_string_ostream Stream(Replacement);
50
51 auto AppendName = [&](llvm::StringRef Name) {
52 if (!Replacement.empty()) {
53 Stream << ", ";
54 }
55 if (Lambda->getCaptureDefault() == LCD_ByRef && Name != "this") {
56 Stream << "&" << Name;
57 } else {
58 Stream << Name;
59 }
60 };
61
62 for (const LambdaCapture &Capture : Lambda->implicit_captures()) {
63 assert(Capture.isImplicit());
64 if (Capture.capturesVariable() && Capture.isImplicit()) {
65 AppendName(Capture.getCapturedVar()->getName());
66 } else if (Capture.capturesThis()) {
67 AppendName("this");
68 }
69 }
70 if (!Replacement.empty() && !Lambda->explicit_captures().empty()) {
71 // Add back separator if we are adding explicit capture variables.
72 Stream << ", ";
73 }
74 return Replacement;
75}
76
77void MisleadingCaptureDefaultByValueCheck::check(
78 const MatchFinder::MatchResult &Result) {
79 const auto *Lambda = Result.Nodes.getNodeAs<LambdaExpr>(ID: "lambda");
80 if (!Lambda)
81 return;
82
83 if (Lambda->getCaptureDefault() == LCD_ByCopy) {
84 bool IsThisImplicitlyCaptured = std::any_of(
85 first: Lambda->implicit_capture_begin(), last: Lambda->implicit_capture_end(),
86 pred: [](const LambdaCapture &Capture) { return Capture.capturesThis(); });
87 auto Diag = diag(Loc: Lambda->getCaptureDefaultLoc(),
88 Description: "lambdas that %select{|implicitly }0capture 'this' "
89 "should not specify a by-value capture default")
90 << IsThisImplicitlyCaptured;
91
92 std::string ReplacementText = createReplacementText(Lambda);
93 SourceLocation DefaultCaptureEnd =
94 findDefaultCaptureEnd(Lambda, Context&: *Result.Context);
95 Diag << FixItHint::CreateReplacement(
96 RemoveRange: CharSourceRange::getCharRange(B: Lambda->getCaptureDefaultLoc(),
97 E: DefaultCaptureEnd),
98 Code: ReplacementText);
99 }
100}
101
102} // namespace clang::tidy::cppcoreguidelines
103

source code of clang-tools-extra/clang-tidy/cppcoreguidelines/MisleadingCaptureDefaultByValueCheck.cpp