llvm-capstone/clang-tools-extra/clang-tidy/readability/ContainerSizeEmptyCheck.cpp
Chandler Carruth 2946cd7010 Update the file headers across all of the LLVM projects in the monorepo
to reflect the new license.

We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.

Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.

llvm-svn: 351636
2019-01-19 08:50:56 +00:00

233 lines
9.1 KiB
C++

//===--- ContainerSizeEmptyCheck.cpp - clang-tidy -------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "ContainerSizeEmptyCheck.h"
#include "../utils/ASTUtils.h"
#include "../utils/Matchers.h"
#include "clang/AST/ASTContext.h"
#include "clang/ASTMatchers/ASTMatchers.h"
#include "clang/Lex/Lexer.h"
#include "llvm/ADT/StringRef.h"
using namespace clang::ast_matchers;
namespace clang {
namespace tidy {
namespace readability {
using utils::IsBinaryOrTernary;
ContainerSizeEmptyCheck::ContainerSizeEmptyCheck(StringRef Name,
ClangTidyContext *Context)
: ClangTidyCheck(Name, Context) {}
void ContainerSizeEmptyCheck::registerMatchers(MatchFinder *Finder) {
// Only register the matchers for C++; the functionality currently does not
// provide any benefit to other languages, despite being benign.
if (!getLangOpts().CPlusPlus)
return;
const auto ValidContainer = qualType(hasUnqualifiedDesugaredType(
recordType(hasDeclaration(cxxRecordDecl(isSameOrDerivedFrom(
namedDecl(
has(cxxMethodDecl(
isConst(), parameterCountIs(0), isPublic(),
hasName("size"),
returns(qualType(isInteger(), unless(booleanType()))))
.bind("size")),
has(cxxMethodDecl(isConst(), parameterCountIs(0), isPublic(),
hasName("empty"), returns(booleanType()))
.bind("empty")))
.bind("container")))))));
const auto WrongUse = anyOf(
hasParent(binaryOperator(
matchers::isComparisonOperator(),
hasEitherOperand(ignoringImpCasts(anyOf(
integerLiteral(equals(1)), integerLiteral(equals(0))))))
.bind("SizeBinaryOp")),
hasParent(implicitCastExpr(
hasImplicitDestinationType(booleanType()),
anyOf(
hasParent(unaryOperator(hasOperatorName("!")).bind("NegOnSize")),
anything()))),
hasParent(explicitCastExpr(hasDestinationType(booleanType()))));
Finder->addMatcher(
cxxMemberCallExpr(on(expr(anyOf(hasType(ValidContainer),
hasType(pointsTo(ValidContainer)),
hasType(references(ValidContainer))))),
callee(cxxMethodDecl(hasName("size"))), WrongUse,
unless(hasAncestor(cxxMethodDecl(
ofClass(equalsBoundNode("container"))))))
.bind("SizeCallExpr"),
this);
// Empty constructor matcher.
const auto DefaultConstructor = cxxConstructExpr(
hasDeclaration(cxxConstructorDecl(isDefaultConstructor())));
// Comparison to empty string or empty constructor.
const auto WrongComparend = anyOf(
ignoringImpCasts(stringLiteral(hasSize(0))),
ignoringImpCasts(cxxBindTemporaryExpr(has(DefaultConstructor))),
ignoringImplicit(DefaultConstructor),
cxxConstructExpr(
hasDeclaration(cxxConstructorDecl(isCopyConstructor())),
has(expr(ignoringImpCasts(DefaultConstructor)))),
cxxConstructExpr(
hasDeclaration(cxxConstructorDecl(isMoveConstructor())),
has(expr(ignoringImpCasts(DefaultConstructor)))));
// Match the object being compared.
const auto STLArg =
anyOf(unaryOperator(
hasOperatorName("*"),
hasUnaryOperand(
expr(hasType(pointsTo(ValidContainer))).bind("Pointee"))),
expr(hasType(ValidContainer)).bind("STLObject"));
Finder->addMatcher(
cxxOperatorCallExpr(
anyOf(hasOverloadedOperatorName("=="),
hasOverloadedOperatorName("!=")),
anyOf(allOf(hasArgument(0, WrongComparend), hasArgument(1, STLArg)),
allOf(hasArgument(0, STLArg), hasArgument(1, WrongComparend))),
unless(hasAncestor(
cxxMethodDecl(ofClass(equalsBoundNode("container"))))))
.bind("BinCmp"),
this);
}
void ContainerSizeEmptyCheck::check(const MatchFinder::MatchResult &Result) {
const auto *MemberCall =
Result.Nodes.getNodeAs<CXXMemberCallExpr>("SizeCallExpr");
const auto *BinCmp = Result.Nodes.getNodeAs<CXXOperatorCallExpr>("BinCmp");
const auto *BinaryOp = Result.Nodes.getNodeAs<BinaryOperator>("SizeBinaryOp");
const auto *Pointee = Result.Nodes.getNodeAs<Expr>("Pointee");
const auto *E =
MemberCall
? MemberCall->getImplicitObjectArgument()
: (Pointee ? Pointee : Result.Nodes.getNodeAs<Expr>("STLObject"));
FixItHint Hint;
std::string ReplacementText =
Lexer::getSourceText(CharSourceRange::getTokenRange(E->getSourceRange()),
*Result.SourceManager, getLangOpts());
if (BinCmp && IsBinaryOrTernary(E)) {
// Not just a DeclRefExpr, so parenthesize to be on the safe side.
ReplacementText = "(" + ReplacementText + ")";
}
if (E->getType()->isPointerType())
ReplacementText += "->empty()";
else
ReplacementText += ".empty()";
if (BinCmp) {
if (BinCmp->getOperator() == OO_ExclaimEqual) {
ReplacementText = "!" + ReplacementText;
}
Hint =
FixItHint::CreateReplacement(BinCmp->getSourceRange(), ReplacementText);
} else if (BinaryOp) { // Determine the correct transformation.
bool Negation = false;
const bool ContainerIsLHS =
!llvm::isa<IntegerLiteral>(BinaryOp->getLHS()->IgnoreImpCasts());
const auto OpCode = BinaryOp->getOpcode();
uint64_t Value = 0;
if (ContainerIsLHS) {
if (const auto *Literal = llvm::dyn_cast<IntegerLiteral>(
BinaryOp->getRHS()->IgnoreImpCasts()))
Value = Literal->getValue().getLimitedValue();
else
return;
} else {
Value =
llvm::dyn_cast<IntegerLiteral>(BinaryOp->getLHS()->IgnoreImpCasts())
->getValue()
.getLimitedValue();
}
// Constant that is not handled.
if (Value > 1)
return;
if (Value == 1 && (OpCode == BinaryOperatorKind::BO_EQ ||
OpCode == BinaryOperatorKind::BO_NE))
return;
// Always true, no warnings for that.
if ((OpCode == BinaryOperatorKind::BO_GE && Value == 0 && ContainerIsLHS) ||
(OpCode == BinaryOperatorKind::BO_LE && Value == 0 && !ContainerIsLHS))
return;
// Do not warn for size > 1, 1 < size, size <= 1, 1 >= size.
if (Value == 1) {
if ((OpCode == BinaryOperatorKind::BO_GT && ContainerIsLHS) ||
(OpCode == BinaryOperatorKind::BO_LT && !ContainerIsLHS))
return;
if ((OpCode == BinaryOperatorKind::BO_LE && ContainerIsLHS) ||
(OpCode == BinaryOperatorKind::BO_GE && !ContainerIsLHS))
return;
}
if (OpCode == BinaryOperatorKind::BO_NE && Value == 0)
Negation = true;
if ((OpCode == BinaryOperatorKind::BO_GT ||
OpCode == BinaryOperatorKind::BO_GE) &&
ContainerIsLHS)
Negation = true;
if ((OpCode == BinaryOperatorKind::BO_LT ||
OpCode == BinaryOperatorKind::BO_LE) &&
!ContainerIsLHS)
Negation = true;
if (Negation)
ReplacementText = "!" + ReplacementText;
Hint = FixItHint::CreateReplacement(BinaryOp->getSourceRange(),
ReplacementText);
} else {
// If there is a conversion above the size call to bool, it is safe to just
// replace size with empty.
if (const auto *UnaryOp =
Result.Nodes.getNodeAs<UnaryOperator>("NegOnSize"))
Hint = FixItHint::CreateReplacement(UnaryOp->getSourceRange(),
ReplacementText);
else
Hint = FixItHint::CreateReplacement(MemberCall->getSourceRange(),
"!" + ReplacementText);
}
if (MemberCall) {
diag(MemberCall->getBeginLoc(),
"the 'empty' method should be used to check "
"for emptiness instead of 'size'")
<< Hint;
} else {
diag(BinCmp->getBeginLoc(),
"the 'empty' method should be used to check "
"for emptiness instead of comparing to an empty object")
<< Hint;
}
const auto *Container = Result.Nodes.getNodeAs<NamedDecl>("container");
if (const auto *CTS = dyn_cast<ClassTemplateSpecializationDecl>(Container)) {
// The definition of the empty() method is the same for all implicit
// instantiations. In order to avoid duplicate or inconsistent warnings
// (depending on how deduplication is done), we use the same class name
// for all implicit instantiations of a template.
if (CTS->getSpecializationKind() == TSK_ImplicitInstantiation)
Container = CTS->getSpecializedTemplate();
}
const auto *Empty = Result.Nodes.getNodeAs<FunctionDecl>("empty");
diag(Empty->getLocation(), "method %0::empty() defined here",
DiagnosticIDs::Note)
<< Container;
}
} // namespace readability
} // namespace tidy
} // namespace clang