[libcxx-commits] [libcxx] [libc++][string_view] Applied `[[nodiscard]]` (PR #169010)

[Hristo Hristov via libcxx-commits]

================
@@ -474,225 +478,232 @@ public:
   }
 #  endif
 
-  _LIBCPP_CONSTEXPR_SINCE_CXX14 int compare(basic_string_view __sv) const _NOEXCEPT {
+  [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 int compare(basic_string_view __sv) const _NOEXCEPT {
     size_type __rlen = std::min(size(), __sv.size());
     int __retval     = _Traits::compare(data(), __sv.data(), __rlen);
     if (__retval == 0) // first __rlen chars matched
       __retval = size() == __sv.size() ? 0 : (size() < __sv.size() ? -1 : 1);
     return __retval;
   }
 
-  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI int
+  [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI int
   compare(size_type __pos1, size_type __n1, basic_string_view __sv) const {
     return substr(__pos1, __n1).compare(__sv);
   }
 
-  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI int
+  [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI int
   compare(size_type __pos1, size_type __n1, basic_string_view __sv, size_type __pos2, size_type __n2) const {
     return substr(__pos1, __n1).compare(__sv.substr(__pos2, __n2));
   }
 
-  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI int
+  [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI int
   compare(const _CharT* _LIBCPP_DIAGNOSE_NULLPTR __s) const _NOEXCEPT {
     return compare(basic_string_view(__s));
   }
 
-  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI int
+  [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI int
   compare(size_type __pos1, size_type __n1, const _CharT* _LIBCPP_DIAGNOSE_NULLPTR __s) const {
     return substr(__pos1, __n1).compare(basic_string_view(__s));
   }
 
-  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI int
+  [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI int
   compare(size_type __pos1, size_type __n1, const _CharT* __s, size_type __n2) const
       _LIBCPP_DIAGNOSE_NULLPTR_IF(__n2 != 0 && __s == nullptr, " if n2 is not zero") {
     return substr(__pos1, __n1).compare(basic_string_view(__s, __n2));
   }
 
   // find
-  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
+  [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
   find(basic_string_view __s, size_type __pos = 0) const _NOEXCEPT {
     return std::__str_find<value_type, size_type, traits_type, npos>(data(), size(), __s.data(), __pos, __s.size());
   }
 
-  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type find(_CharT __c, size_type __pos = 0) const _NOEXCEPT {
+  [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
+  find(_CharT __c, size_type __pos = 0) const _NOEXCEPT {
     return std::__str_find<value_type, size_type, traits_type, npos>(data(), size(), __c, __pos);
   }
 
-  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
+  [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
   find(const _CharT* __s, size_type __pos, size_type __n) const _NOEXCEPT
       _LIBCPP_DIAGNOSE_NULLPTR_IF(__n != 0 && __s == nullptr, " if n is not zero") {
     _LIBCPP_ASSERT_NON_NULL(__n == 0 || __s != nullptr, "string_view::find(): received nullptr");
     return std::__str_find<value_type, size_type, traits_type, npos>(data(), size(), __s, __pos, __n);
   }
 
-  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
+  [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
   find(const _CharT* _LIBCPP_DIAGNOSE_NULLPTR __s, size_type __pos = 0) const _NOEXCEPT {
     _LIBCPP_ASSERT_NON_NULL(__s != nullptr, "string_view::find(): received nullptr");
     return std::__str_find<value_type, size_type, traits_type, npos>(
         data(), size(), __s, __pos, traits_type::length(__s));
   }
 
   // rfind
-  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
+  [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
   rfind(basic_string_view __s, size_type __pos = npos) const _NOEXCEPT {
     return std::__str_rfind<value_type, size_type, traits_type, npos>(data(), size(), __s.data(), __pos, __s.size());
   }
 
-  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
+  [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
   rfind(_CharT __c, size_type __pos = npos) const _NOEXCEPT {
     return std::__str_rfind<value_type, size_type, traits_type, npos>(data(), size(), __c, __pos);
   }
 
-  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
+  [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
   rfind(const _CharT* __s, size_type __pos, size_type __n) const _NOEXCEPT
       _LIBCPP_DIAGNOSE_NULLPTR_IF(__n != 0 && __s == nullptr, " if n is not zero") {
     _LIBCPP_ASSERT_NON_NULL(__n == 0 || __s != nullptr, "string_view::rfind(): received nullptr");
     return std::__str_rfind<value_type, size_type, traits_type, npos>(data(), size(), __s, __pos, __n);
   }
 
-  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
+  [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
   rfind(const _CharT* _LIBCPP_DIAGNOSE_NULLPTR __s, size_type __pos = npos) const _NOEXCEPT {
     _LIBCPP_ASSERT_NON_NULL(__s != nullptr, "string_view::rfind(): received nullptr");
     return std::__str_rfind<value_type, size_type, traits_type, npos>(
         data(), size(), __s, __pos, traits_type::length(__s));
   }
 
   // find_first_of
-  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
+  [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
   find_first_of(basic_string_view __s, size_type __pos = 0) const _NOEXCEPT {
     return std::__str_find_first_of<value_type, size_type, traits_type, npos>(
         data(), size(), __s.data(), __pos, __s.size());
   }
 
-  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
+  [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
   find_first_of(_CharT __c, size_type __pos = 0) const _NOEXCEPT {
     return find(__c, __pos);
   }
 
-  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
+  [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
   find_first_of(const _CharT* __s, size_type __pos, size_type __n) const _NOEXCEPT
       _LIBCPP_DIAGNOSE_NULLPTR_IF(__n != 0 && __s == nullptr, " if n is not zero") {
     _LIBCPP_ASSERT_NON_NULL(__n == 0 || __s != nullptr, "string_view::find_first_of(): received nullptr");
     return std::__str_find_first_of<value_type, size_type, traits_type, npos>(data(), size(), __s, __pos, __n);
   }
 
-  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
+  [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
   find_first_of(const _CharT* _LIBCPP_DIAGNOSE_NULLPTR __s, size_type __pos = 0) const _NOEXCEPT {
     _LIBCPP_ASSERT_NON_NULL(__s != nullptr, "string_view::find_first_of(): received nullptr");
     return std::__str_find_first_of<value_type, size_type, traits_type, npos>(
         data(), size(), __s, __pos, traits_type::length(__s));
   }
 
   // find_last_of
-  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
+  [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
   find_last_of(basic_string_view __s, size_type __pos = npos) const _NOEXCEPT {
     return std::__str_find_last_of<value_type, size_type, traits_type, npos>(
         data(), size(), __s.data(), __pos, __s.size());
   }
 
-  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
+  [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
   find_last_of(_CharT __c, size_type __pos = npos) const _NOEXCEPT {
     return rfind(__c, __pos);
   }
 
-  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
+  [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
   find_last_of(const _CharT* __s, size_type __pos, size_type __n) const _NOEXCEPT
       _LIBCPP_DIAGNOSE_NULLPTR_IF(__n != 0 && __s == nullptr, " if n is not zero") {
     _LIBCPP_ASSERT_NON_NULL(__n == 0 || __s != nullptr, "string_view::find_last_of(): received nullptr");
     return std::__str_find_last_of<value_type, size_type, traits_type, npos>(data(), size(), __s, __pos, __n);
   }
 
-  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
+  [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
   find_last_of(const _CharT* _LIBCPP_DIAGNOSE_NULLPTR __s, size_type __pos = npos) const _NOEXCEPT {
     _LIBCPP_ASSERT_NON_NULL(__s != nullptr, "string_view::find_last_of(): received nullptr");
     return std::__str_find_last_of<value_type, size_type, traits_type, npos>(
         data(), size(), __s, __pos, traits_type::length(__s));
   }
 
   // find_first_not_of
-  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
+  [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
   find_first_not_of(basic_string_view __s, size_type __pos = 0) const _NOEXCEPT {
     return std::__str_find_first_not_of<value_type, size_type, traits_type, npos>(
         data(), size(), __s.data(), __pos, __s.size());
   }
 
-  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
+  [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
   find_first_not_of(_CharT __c, size_type __pos = 0) const _NOEXCEPT {
     return std::__str_find_first_not_of<value_type, size_type, traits_type, npos>(data(), size(), __c, __pos);
   }
 
-  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
+  [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
   find_first_not_of(const _CharT* __s, size_type __pos, size_type __n) const _NOEXCEPT
       _LIBCPP_DIAGNOSE_NULLPTR_IF(__n != 0 && __s == nullptr, " if n is not zero") {
     _LIBCPP_ASSERT_NON_NULL(__n == 0 || __s != nullptr, "string_view::find_first_not_of(): received nullptr");
     return std::__str_find_first_not_of<value_type, size_type, traits_type, npos>(data(), size(), __s, __pos, __n);
   }
 
-  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
+  [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
   find_first_not_of(const _CharT* _LIBCPP_DIAGNOSE_NULLPTR __s, size_type __pos = 0) const _NOEXCEPT {
     _LIBCPP_ASSERT_NON_NULL(__s != nullptr, "string_view::find_first_not_of(): received nullptr");
     return std::__str_find_first_not_of<value_type, size_type, traits_type, npos>(
         data(), size(), __s, __pos, traits_type::length(__s));
   }
 
   // find_last_not_of
-  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
+  [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
   find_last_not_of(basic_string_view __s, size_type __pos = npos) const _NOEXCEPT {
     return std::__str_find_last_not_of<value_type, size_type, traits_type, npos>(
         data(), size(), __s.data(), __pos, __s.size());
   }
 
-  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
+  [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
   find_last_not_of(_CharT __c, size_type __pos = npos) const _NOEXCEPT {
     return std::__str_find_last_not_of<value_type, size_type, traits_type, npos>(data(), size(), __c, __pos);
   }
 
-  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
+  [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
   find_last_not_of(const _CharT* __s, size_type __pos, size_type __n) const _NOEXCEPT
       _LIBCPP_DIAGNOSE_NULLPTR_IF(__n != 0 && __s == nullptr, " if n is not zero") {
     _LIBCPP_ASSERT_NON_NULL(__n == 0 || __s != nullptr, "string_view::find_last_not_of(): received nullptr");
     return std::__str_find_last_not_of<value_type, size_type, traits_type, npos>(data(), size(), __s, __pos, __n);
   }
 
-  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
+  [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
   find_last_not_of(const _CharT* _LIBCPP_DIAGNOSE_NULLPTR __s, size_type __pos = npos) const _NOEXCEPT {
     _LIBCPP_ASSERT_NON_NULL(__s != nullptr, "string_view::find_last_not_of(): received nullptr");
     return std::__str_find_last_not_of<value_type, size_type, traits_type, npos>(
         data(), size(), __s, __pos, traits_type::length(__s));
   }
 
 #  if _LIBCPP_STD_VER >= 20
-  constexpr _LIBCPP_HIDE_FROM_ABI bool starts_with(basic_string_view __s) const noexcept {
+  [[nodiscard]] constexpr _LIBCPP_HIDE_FROM_ABI bool starts_with(basic_string_view __s) const noexcept {
     return size() >= __s.size() && compare(0, __s.size(), __s) == 0;
   }
 
-  constexpr _LIBCPP_HIDE_FROM_ABI bool starts_with(value_type __c) const noexcept {
+  [[nodiscard]] constexpr _LIBCPP_HIDE_FROM_ABI bool starts_with(value_type __c) const noexcept {
     return !empty() && _Traits::eq(front(), __c);
   }
 
-  constexpr _LIBCPP_HIDE_FROM_ABI bool starts_with(const value_type* _LIBCPP_DIAGNOSE_NULLPTR __s) const noexcept {
+  [[nodiscard]] constexpr _LIBCPP_HIDE_FROM_ABI bool
+  starts_with(const value_type* _LIBCPP_DIAGNOSE_NULLPTR __s) const noexcept {
     return starts_with(basic_string_view(__s));
   }
 
-  constexpr _LIBCPP_HIDE_FROM_ABI bool ends_with(basic_string_view __s) const noexcept {
+  [[nodiscard]] constexpr _LIBCPP_HIDE_FROM_ABI bool ends_with(basic_string_view __s) const noexcept {
     return size() >= __s.size() && compare(size() - __s.size(), npos, __s) == 0;
   }
 
-  constexpr _LIBCPP_HIDE_FROM_ABI bool ends_with(value_type __c) const noexcept {
+  [[nodiscard]] constexpr _LIBCPP_HIDE_FROM_ABI bool ends_with(value_type __c) const noexcept {
     return !empty() && _Traits::eq(back(), __c);
   }
 
-  constexpr _LIBCPP_HIDE_FROM_ABI bool ends_with(const value_type* _LIBCPP_DIAGNOSE_NULLPTR __s) const noexcept {
+  [[nodiscard]] constexpr _LIBCPP_HIDE_FROM_ABI bool
+  ends_with(const value_type* _LIBCPP_DIAGNOSE_NULLPTR __s) const noexcept {
     return ends_with(basic_string_view(__s));
   }
 #  endif
 
 #  if _LIBCPP_STD_VER >= 23
-  constexpr _LIBCPP_HIDE_FROM_ABI bool contains(basic_string_view __sv) const noexcept { return find(__sv) != npos; }
+  [[nodiscard]] constexpr _LIBCPP_HIDE_FROM_ABI bool contains(basic_string_view __sv) const noexcept {
+    return find(__sv) != npos;
+  }
 
-  constexpr _LIBCPP_HIDE_FROM_ABI bool contains(value_type __c) const noexcept { return find(__c) != npos; }
+  [[nodiscard]] constexpr _LIBCPP_HIDE_FROM_ABI bool contains(value_type __c) const noexcept {
+    return find(__c) != npos;
+  }
 
-  constexpr _LIBCPP_HIDE_FROM_ABI bool contains(const value_type* _LIBCPP_DIAGNOSE_NULLPTR __s) const {
+  [[nodiscard]] constexpr _LIBCPP_HIDE_FROM_ABI bool contains(const value_type* _LIBCPP_DIAGNOSE_NULLPTR __s) const {
     return find(__s) != npos;
   }
----------------
H-G-Hristov wrote:

Done!

I just noticed that a number of non-member functions and the same operators in `<string>` are also not annotated. Are you working on them or should I do them next?

https://github.com/llvm/llvm-project/pull/169010