[libcxx-commits] [libcxx] [libc++][iterator] Applied `[[nodiscard]]` (PR #172200)

[A. Jiang via libcxx-commits]

================
@@ -0,0 +1,438 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: libcpp-hardening-mode=none
+
+// ADDITIONAL_COMPILE_FLAGS: -D_LIBCPP_ABI_BOUNDED_ITERATORS
+// ADDITIONAL_COMPILE_FLAGS: -D_LIBCPP_ABI_BOUNDED_ITERATORS_IN_STD_ARRAY
+
+// check that <iterator> functions are marked [[nodiscard]]
+
+#include <array>
+#include <initializer_list>
+#include <iterator>
+#include <sstream>
+#include <string_view>
+#include <utility>
+#include <vector>
+
+#include "test_macros.h"
+#include "test_iterators.h"
+
+void test() {
+  int cArr[] = {94, 82, 49};
+  std::vector<int> cont;
+  const std::vector<int> cCont;
+#if TEST_STD_VER >= 11
+  std::initializer_list<int> il;
+#endif
+#if !defined(TEST_HAS_NO_LOCALIZATION)
+  std::stringstream ss;
+#endif
+
+  { // Access
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    std::begin(cArr);
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    std::end(cArr);
+
+#if TEST_STD_VER >= 11
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    std::begin(cont);
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    std::begin(cCont);
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    std::end(cont);
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    std::end(cCont);
+#endif
+#if TEST_STD_VER >= 14
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    std::cbegin(cCont);
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    std::cend(cCont);
+#endif
+  }
+
+  {
+    std::back_insert_iterator<std::vector<int> > it(cont);
+
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    *it;
+  }
+
+  { // __bounded_iter
+    typedef std::basic_string_view<char> Container;
+    ASSERT_SAME_TYPE(Container::const_iterator, std::__bounded_iter<const char*>);
+
+    Container::const_iterator it;
+
+    std::pointer_traits<Container::const_iterator> pt;
+
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    pt.to_address(it);
+  }
+
+#if TEST_STD_VER >= 20
+  {
+    std::common_iterator<int*, sentinel_wrapper<int*>> it;
+
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    *it;
+  }
+#endif
+
+#if TEST_STD_VER >= 20
+  {
+    std::counted_iterator it{random_access_iterator<int*>{cArr}, 3};
+
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    it.base();
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    std::move(it).base();
+
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    it.count();
+
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    *it;
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    *std::as_const(it);
+
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    it + 2;
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    2 + it;
+
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    it - 2;
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    it - it;
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    it - std::default_sentinel;
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    std::default_sentinel - it;
+
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    it[2];
+  }
+#endif
+
+#if TEST_STD_VER >= 17
+  {
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    std::data(cont);
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    std::data(cCont);
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    std::data(cArr);
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    std::data(il);
+  }
+#endif
+
+  {
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    std::distance(cont.begin(), cont.end());
+#if TEST_STD_VER >= 20
+    cpp17_input_iterator<int*> it{cArr};
+    sentinel_wrapper<cpp17_input_iterator<int*>> st;
+
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    std::ranges::distance(it, st);
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    std::ranges::distance(cont.begin(), cont.end());
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    std::ranges::distance(std::move(cont));
+#endif
+  }
+
+#if TEST_STD_VER >= 17
+  { // Empty
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    std::empty(cont);
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    std::empty(cArr);
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    std::empty(il);
+  }
+#endif
+
+  {
+    std::front_insert_iterator<std::vector<int> > it(cont);
+
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    *it;
+
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    std::front_inserter(cont);
+  }
+
+  {
+    std::insert_iterator<std::vector<int> > it(cont, cont.begin());
+
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    *it;
+
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    std::inserter(cont, cont.begin());
+  }
+
+  {
+    std::istream_iterator<char> it;
+
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    *it;
+  }
+
+#if !defined(TEST_HAS_NO_LOCALIZATION)
+  {
+    std::istreambuf_iterator<char> it(ss);
+
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    *it;
+  }
+#endif
+
+#if TEST_STD_VER >= 11
+  {
+    std::move_iterator<random_access_iterator<int*>> it;
+
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    it.base();
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    std::move(it).base();
+
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    *it;
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    it[0];
+
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    it + 1;
+
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    it - 1;
+
+#  if TEST_STD_VER >= 20
+    std::move_sentinel<random_access_iterator<int*>> st;
+
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    st - it;
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    it - st;
+
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    iter_move(it);
+#  endif
+
+    std::move_iterator<random_access_iterator<int*>> otherIt;
+
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    it - otherIt;
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    otherIt - it;
+
+#  if TEST_STD_VER >= 20
+    std::iter_difference_t<random_access_iterator<int*>> diff = st - it;
+
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    diff + it;
+#  endif
+
+    int* i = nullptr;
+
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    std::make_move_iterator(i);
+  }
+#endif
+
+#if TEST_STD_VER >= 20
+  {
+    std::move_sentinel<int*> st;
+
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    st.base();
+  }
+#endif
+
+  {
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    std::next(cArr);
+
+#if TEST_STD_VER >= 20
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    std::ranges::next(cArr);
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    std::ranges::next(cont.begin(), 2);
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    std::ranges::next(cont.begin(), cont.end());
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    std::ranges::next(cont.begin(), 2, cont.end());
+#endif
+  }
+
+#if !defined(TEST_HAS_NO_LOCALIZATION)
+  {
+    std::ostream_iterator<char> it(ss);
+
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    *it;
+  }
+#endif
+
+#if !defined(TEST_HAS_NO_LOCALIZATION)
+  {
+    std::ostreambuf_iterator<char> it(ss);
+
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    *it;
+
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    it.failed();
+  }
+#endif
+
+  {
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    std::prev(cArr, 2);
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    std::prev(cArr);
+
+#if TEST_STD_VER >= 20
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    std::ranges::prev(cArr);
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    std::ranges::prev(cont.end(), 2);
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    std::ranges::prev(cont.end(), 2, cont.begin());
+#endif
+  }
+
+#if TEST_STD_VER >= 14
+  {
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    std::rbegin(cArr);
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    std::rend(cArr);
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    std::rbegin(il);
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    std::rend(il);
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    std::rbegin(cont);
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    std::rbegin(cCont);
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    std::rend(cont);
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    std::rend(cCont);
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    std::crbegin(cCont);
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    std::crend(cCont);
+  }
+#endif
+
+  {
+    std::reverse_iterator<random_access_iterator<const char*> > it;
+
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    it.base();
+
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    *it;
+
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    it - 1;
+
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    it[0];
+
+#if _LIBCPP_STD_VER >= 20
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    iter_move(it);
+#endif
+
+    std::reverse_iterator<random_access_iterator<const char*> > otherIt;
+
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    otherIt - it;
+
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    it - otherIt;
+
+#if TEST_STD_VER >= 14
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    std::make_reverse_iterator(cont.end());
+#endif
+  }
+
+#if TEST_STD_VER >= 17
+  {
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    std::size(cArr);
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    std::size(cont);
+    // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+    std::size(cCont);
+  }
+#endif
+
+  { // __static_bounded_iter
----------------
frederick-vs-ja wrote:

Yeah. I'll be happier with wrapping iterators handled in another PR.

https://github.com/llvm/llvm-project/pull/172200