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base / containers / contains_nocompile.nc [blame]
// Copyright 2020 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// This is a "No Compile Test" suite.
// https://dev.chromium.org/developers/testing/no-compile-tests
#include <set>
#include <string_view>
#include "base/containers/contains.h"
namespace base {
// The following code would perform a linear search through the set which is
// likely unexpected and not intended. This is because the expression
// `set.find(kFoo)` is ill-formed, since there is no implimit conversion from
// std::string_view to `std::string`. This means Contains would fall back to the
// general purpose `base::ranges::find(set, kFoo)` linear search.
// To fix this clients can either use a more generic comparator like std::less<>
// (in this case `set.find()` accepts any type that is comparable to a
// std::string), or pass an explicit projection parameter to Contains, at which
// point it will always perform a linear search.
void UnexpectedLinearSearch() {
constexpr std::string_view kFoo = "foo";
std::set<std::string> set = {"foo", "bar", "baz"};
Contains(set, kFoo); // expected-error@*:* {{About to perform linear search on an associative container}}
}
} // namespace base