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//===- RedundantStringInitCheck.cpp - clang-tidy ----------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "RedundantStringInitCheck.h"
#include "clang/ASTMatchers/ASTMatchers.h"
using namespace clang::ast_matchers;
namespace clang {
namespace tidy {
namespace readability {
namespace {
AST_MATCHER(StringLiteral, lengthIsZero) { return Node.getLength() == 0; }
AST_MATCHER_P(Expr, ignoringImplicit,
ast_matchers::internal::Matcher<Expr>, InnerMatcher) {
return InnerMatcher.matches(*Node.IgnoreImplicit(), Finder, Builder);
}
} // namespace
void RedundantStringInitCheck::registerMatchers(MatchFinder *Finder) {
if (!getLangOpts().CPlusPlus)
return;
// Match string constructor.
const auto StringConstructorExpr = expr(anyOf(
cxxConstructExpr(argumentCountIs(1),
hasDeclaration(cxxMethodDecl(hasName("basic_string")))),
// If present, the second argument is the alloc object which must not
// be present explicitly.
cxxConstructExpr(argumentCountIs(2),
hasDeclaration(cxxMethodDecl(hasName("basic_string"))),
hasArgument(1, cxxDefaultArgExpr()))));
// Match a string constructor expression with an empty string literal.
const auto EmptyStringCtorExpr =
cxxConstructExpr(StringConstructorExpr,
hasArgument(0, ignoringParenImpCasts(
stringLiteral(lengthIsZero()))));
const auto EmptyStringCtorExprWithTemporaries =
expr(ignoringImplicit(
cxxConstructExpr(StringConstructorExpr,
hasArgument(0, ignoringImplicit(EmptyStringCtorExpr)))));
// Match a variable declaration with an empty string literal as initializer.
// Examples:
// string foo = "";
// string bar("");
Finder->addMatcher(
namedDecl(varDecl(hasType(cxxRecordDecl(hasName("basic_string"))),
hasInitializer(
expr(anyOf(EmptyStringCtorExpr,
EmptyStringCtorExprWithTemporaries))
.bind("expr"))),
unless(parmVarDecl()))
.bind("decl"),
this);
}
void RedundantStringInitCheck::check(const MatchFinder::MatchResult &Result) {
const auto *CtorExpr = Result.Nodes.getNodeAs<Expr>("expr");
const auto *Decl = Result.Nodes.getNodeAs<NamedDecl>("decl");
diag(CtorExpr->getExprLoc(), "redundant string initialization")
<< FixItHint::CreateReplacement(CtorExpr->getSourceRange(),
Decl->getName());
}
} // namespace readability
} // namespace tidy
} // namespace clang
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