1 //===--- ShrinkToFitCheck.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 "ShrinkToFitCheck.h"
10 #include "clang/AST/ASTContext.h"
11 #include "clang/ASTMatchers/ASTMatchFinder.h"
12 #include "clang/Lex/Lexer.h"
13 #include "llvm/ADT/StringRef.h"
14
15 using namespace clang::ast_matchers;
16
17 namespace clang {
18 namespace tidy {
19 namespace modernize {
20
registerMatchers(MatchFinder * Finder)21 void ShrinkToFitCheck::registerMatchers(MatchFinder *Finder) {
22 // Swap as a function need not to be considered, because rvalue can not
23 // be bound to a non-const reference.
24 const auto ShrinkableAsMember =
25 memberExpr(member(valueDecl().bind("ContainerDecl")));
26 const auto ShrinkableAsDecl =
27 declRefExpr(hasDeclaration(valueDecl().bind("ContainerDecl")));
28 const auto CopyCtorCall = cxxConstructExpr(hasArgument(
29 0, anyOf(ShrinkableAsMember, ShrinkableAsDecl,
30 unaryOperator(has(ignoringParenImpCasts(ShrinkableAsMember))),
31 unaryOperator(has(ignoringParenImpCasts(ShrinkableAsDecl))))));
32 const auto SwapParam =
33 expr(anyOf(memberExpr(member(equalsBoundNode("ContainerDecl"))),
34 declRefExpr(hasDeclaration(equalsBoundNode("ContainerDecl"))),
35 unaryOperator(has(ignoringParenImpCasts(
36 memberExpr(member(equalsBoundNode("ContainerDecl")))))),
37 unaryOperator(has(ignoringParenImpCasts(declRefExpr(
38 hasDeclaration(equalsBoundNode("ContainerDecl"))))))));
39
40 Finder->addMatcher(
41 cxxMemberCallExpr(
42 on(hasType(hasCanonicalType(hasDeclaration(namedDecl(
43 hasAnyName("std::basic_string", "std::deque", "std::vector")))))),
44 callee(cxxMethodDecl(hasName("swap"))),
45 has(ignoringParenImpCasts(memberExpr(traverse(
46 ast_type_traits::TK_AsIs, hasDescendant(CopyCtorCall))))),
47 hasArgument(0, SwapParam.bind("ContainerToShrink")),
48 unless(isInTemplateInstantiation()))
49 .bind("CopyAndSwapTrick"),
50 this);
51 }
52
check(const MatchFinder::MatchResult & Result)53 void ShrinkToFitCheck::check(const MatchFinder::MatchResult &Result) {
54 const auto *MemberCall =
55 Result.Nodes.getNodeAs<CXXMemberCallExpr>("CopyAndSwapTrick");
56 const auto *Container = Result.Nodes.getNodeAs<Expr>("ContainerToShrink");
57 FixItHint Hint;
58
59 if (!MemberCall->getBeginLoc().isMacroID()) {
60 const LangOptions &Opts = getLangOpts();
61 std::string ReplacementText;
62 if (const auto *UnaryOp = llvm::dyn_cast<UnaryOperator>(Container)) {
63 ReplacementText = std::string(
64 Lexer::getSourceText(CharSourceRange::getTokenRange(
65 UnaryOp->getSubExpr()->getSourceRange()),
66 *Result.SourceManager, Opts));
67 ReplacementText += "->shrink_to_fit()";
68 } else {
69 ReplacementText = std::string(Lexer::getSourceText(
70 CharSourceRange::getTokenRange(Container->getSourceRange()),
71 *Result.SourceManager, Opts));
72 ReplacementText += ".shrink_to_fit()";
73 }
74
75 Hint = FixItHint::CreateReplacement(MemberCall->getSourceRange(),
76 ReplacementText);
77 }
78
79 diag(MemberCall->getBeginLoc(), "the shrink_to_fit method should be used "
80 "to reduce the capacity of a shrinkable "
81 "container")
82 << Hint;
83 }
84
85 } // namespace modernize
86 } // namespace tidy
87 } // namespace clang
88