[libc++] Diagnose passing null pointers to a bunch of APIs #148585

philnik777 · 2025-07-14T08:34:04Z

No description provided.

github-actions · 2025-07-14T08:37:51Z

✅ With the latest revision this PR passed the C/C++ code formatter.

llvmbot · 2025-07-16T14:07:42Z

@llvm/pr-subscribers-libcxx

Author: Nikolas Klauser (philnik777)

Changes

Patch is 34.04 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/148585.diff

11 Files Affected:

(modified) libcxx/.clang-format (+1)
(modified) libcxx/include/__config (+14)
(modified) libcxx/include/__memory/construct_at.h (+4-4)
(modified) libcxx/include/print (+9-5)
(modified) libcxx/include/string (+30-15)
(modified) libcxx/include/string_view (+31-21)
(added) libcxx/test/libcxx/algorithms/specialized.algorithms/nonnull.verify.cpp (+28)
(added) libcxx/test/libcxx/input.output/iostream.format/print.fun/nonnull.verify.cpp (+21)
(modified) libcxx/test/libcxx/strings/basic.string/nonnull.verify.cpp (+24-1)
(modified) libcxx/test/libcxx/strings/string.view/assert.ctor.pointer.pass.cpp (+3)
(added) libcxx/test/libcxx/strings/string.view/nonnull.verify.cpp (+53)

diff --git a/libcxx/.clang-format b/libcxx/.clang-format
index f372ac9619997..9557b955cd72c 100644
--- a/libcxx/.clang-format
+++ b/libcxx/.clang-format
@@ -33,6 +33,7 @@ AttributeMacros: [
                   '_LIBCPP_DEPRECATED_IN_CXX20',
                   '_LIBCPP_DEPRECATED_IN_CXX23',
                   '_LIBCPP_DEPRECATED',
+                  '_LIBCPP_DIAGNOSE_NULLPTR_IF',
                   '_LIBCPP_EXCLUDE_FROM_EXPLICIT_INSTANTIATION',
                   '_LIBCPP_EXPORTED_FROM_ABI',
                   '_LIBCPP_EXTERN_TEMPLATE_TYPE_VIS',
diff --git a/libcxx/include/__config b/libcxx/include/__config
index d940461c30234..3b3e4cb6f413e 100644
--- a/libcxx/include/__config
+++ b/libcxx/include/__config
@@ -1095,6 +1095,20 @@ typedef __char32_t char32_t;
 #    define _LIBCPP_DIAGNOSE_WARNING(...)
 #  endif
 
+#  if __has_attribute(__diagnose_if__) && !defined(_LIBCPP_APPLE_CLANG_VER) &&                                         \
+      (!defined(_LIBCPP_CLANG_VER) || _LIBCPP_CLANG_VER >= 2001)
+#    define _LIBCPP_DIAGNOSE_IF(...) __attribute__((__diagnose_if__(__VA_ARGS__)))
+#  else
+#    define _LIBCPP_DIAGNOSE_IF(...)
+#  endif
+
+#  define _LIBCPP_DIAGNOSE_NULLPTR_IF(condition, condition_description)                                                \
+    _LIBCPP_DIAGNOSE_IF(                                                                                               \
+        condition,                                                                                                     \
+        "null passed to calle that requires a non-null argument" condition_description,                                \
+        "warning",                                                                                                     \
+        "nonnull")
+
 #  if __has_cpp_attribute(_Clang::__lifetimebound__)
 #    define _LIBCPP_LIFETIMEBOUND [[_Clang::__lifetimebound__]]
 #  else
diff --git a/libcxx/include/__memory/construct_at.h b/libcxx/include/__memory/construct_at.h
index b64e64b5a29b0..a59e2f3bd5ea5 100644
--- a/libcxx/include/__memory/construct_at.h
+++ b/libcxx/include/__memory/construct_at.h
@@ -32,8 +32,8 @@ _LIBCPP_BEGIN_NAMESPACE_STD
 
 #if _LIBCPP_STD_VER >= 20
 
-template <class _Tp, class... _Args, class = decltype(::new(std::declval<void*>()) _Tp(std::declval<_Args>()...))>
-_LIBCPP_HIDE_FROM_ABI constexpr _Tp* construct_at(_Tp* __location, _Args&&... __args) {
+template <class _Tp, class... _Args, class = decltype(::new (std::declval<void*>()) _Tp(std::declval<_Args>()...))>
+_LIBCPP_HIDE_FROM_ABI constexpr _Tp* construct_at(_Tp* _LIBCPP_DIAGNOSE_NULLPTR __location, _Args&&... __args) {
   _LIBCPP_ASSERT_NON_NULL(__location != nullptr, "null pointer given to construct_at");
   return ::new (static_cast<void*>(__location)) _Tp(std::forward<_Args>(__args)...);
 }
@@ -73,13 +73,13 @@ _LIBCPP_HIDE_FROM_ABI constexpr void __destroy_at(_Tp* __loc) {
 #if _LIBCPP_STD_VER >= 17
 
 template <class _Tp, enable_if_t<!is_array_v<_Tp>, int> = 0>
-_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void destroy_at(_Tp* __loc) {
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void destroy_at(_Tp* _LIBCPP_DIAGNOSE_NULLPTR __loc) {
   std::__destroy_at(__loc);
 }
 
 #  if _LIBCPP_STD_VER >= 20
 template <class _Tp, enable_if_t<is_array_v<_Tp>, int> = 0>
-_LIBCPP_HIDE_FROM_ABI constexpr void destroy_at(_Tp* __loc) {
+_LIBCPP_HIDE_FROM_ABI constexpr void destroy_at(_Tp* _LIBCPP_DIAGNOSE_NULLPTR __loc) {
   std::__destroy_at(__loc);
 }
 #  endif
diff --git a/libcxx/include/print b/libcxx/include/print
index be05d30e0147f..0ff314c22dcd9 100644
--- a/libcxx/include/print
+++ b/libcxx/include/print
@@ -329,7 +329,8 @@ __vprint_unicode([[maybe_unused]] FILE* __stream,
 } // namespace __print
 
 template <class... _Args>
-_LIBCPP_HIDE_FROM_ABI void print(FILE* __stream, format_string<_Args...> __fmt, _Args&&... __args) {
+_LIBCPP_HIDE_FROM_ABI void
+print(FILE* _LIBCPP_DIAGNOSE_NULLPTR __stream, format_string<_Args...> __fmt, _Args&&... __args) {
 #    if _LIBCPP_HAS_UNICODE
   if constexpr (__print::__use_unicode_execution_charset)
     __print::__vprint_unicode(__stream, __fmt.get(), std::make_format_args(__args...), false);
@@ -346,7 +347,8 @@ _LIBCPP_HIDE_FROM_ABI void print(format_string<_Args...> __fmt, _Args&&... __arg
 }
 
 template <class... _Args>
-_LIBCPP_HIDE_FROM_ABI void println(FILE* __stream, format_string<_Args...> __fmt, _Args&&... __args) {
+_LIBCPP_HIDE_FROM_ABI void
+println(FILE* _LIBCPP_DIAGNOSE_NULLPTR __stream, format_string<_Args...> __fmt, _Args&&... __args) {
 #    if _LIBCPP_HAS_UNICODE
   // Note the wording in the Standard is inefficient. The output of
   // std::format is a std::string which is then copied. This solution
@@ -361,7 +363,7 @@ _LIBCPP_HIDE_FROM_ABI void println(FILE* __stream, format_string<_Args...> __fmt
 }
 
 template <class = void> // TODO PRINT template or availability markup fires too eagerly (http://llvm.org/PR61563).
-_LIBCPP_HIDE_FROM_ABI inline void println(FILE* __stream) {
+_LIBCPP_HIDE_FROM_ABI inline void println(FILE* _LIBCPP_DIAGNOSE_NULLPTR __stream) {
   std::print(__stream, "\n");
 }
 
@@ -377,7 +379,8 @@ _LIBCPP_HIDE_FROM_ABI void println(format_string<_Args...> __fmt, _Args&&... __a
 
 #    if _LIBCPP_HAS_UNICODE
 template <class = void> // TODO PRINT template or availability markup fires too eagerly (http://llvm.org/PR61563).
-_LIBCPP_HIDE_FROM_ABI inline void vprint_unicode(FILE* __stream, string_view __fmt, format_args __args) {
+_LIBCPP_HIDE_FROM_ABI inline void
+vprint_unicode(FILE* _LIBCPP_DIAGNOSE_NULLPTR __stream, string_view __fmt, format_args __args) {
   __print::__vprint_unicode(__stream, __fmt, __args, false);
 }
 
@@ -389,7 +392,8 @@ _LIBCPP_HIDE_FROM_ABI inline void vprint_unicode(string_view __fmt, format_args
 #    endif // _LIBCPP_HAS_UNICODE
 
 template <class = void> // TODO PRINT template or availability markup fires too eagerly (http://llvm.org/PR61563).
-_LIBCPP_HIDE_FROM_ABI inline void vprint_nonunicode(FILE* __stream, string_view __fmt, format_args __args) {
+_LIBCPP_HIDE_FROM_ABI inline void
+vprint_nonunicode(FILE* _LIBCPP_DIAGNOSE_NULLPTR __stream, string_view __fmt, format_args __args) {
   __print::__vprint_nonunicode(__stream, __fmt, __args, false);
 }
 
diff --git a/libcxx/include/string b/libcxx/include/string
index 514dd91c7c172..88c0ed40e3bf7 100644
--- a/libcxx/include/string
+++ b/libcxx/include/string
@@ -1065,13 +1065,15 @@ public:
   basic_string(nullptr_t) = delete;
 #  endif
 
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string(const _CharT* __s, size_type __n) {
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string(const _CharT* __s, size_type __n)
+      _LIBCPP_DIAGNOSE_NULLPTR_IF(__n != 0 && __s == nullptr, " if n is not zero") {
     _LIBCPP_ASSERT_NON_NULL(__n == 0 || __s != nullptr, "basic_string(const char*, n) detected nullptr");
     __init(__s, __n);
   }
 
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20
   basic_string(const _CharT* __s, size_type __n, const _Allocator& __a)
+      _LIBCPP_DIAGNOSE_NULLPTR_IF(__n != 0 && __s == nullptr, " if n is not zero")
       : __alloc_(__a) {
     _LIBCPP_ASSERT_NON_NULL(__n == 0 || __s != nullptr, "basic_string(const char*, n, allocator) detected nullptr");
     __init(__s, __n);
@@ -1394,7 +1396,8 @@ public:
     return append(__sv.data() + __pos, std::min(__n, __sz - __pos));
   }
 
-  _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string& append(const value_type* __s, size_type __n);
+  _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string& append(const value_type* __s, size_type __n)
+      _LIBCPP_DIAGNOSE_NULLPTR_IF(__n != 0 && __s == nullptr, " if n is not zero");
   _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string& append(const value_type* _LIBCPP_DIAGNOSE_NULLPTR __s);
   _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string& append(size_type __n, value_type __c);
 
@@ -1521,8 +1524,9 @@ public:
     return assign(__sv.data() + __pos, std::min(__n, __sz - __pos));
   }
 
-  _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string& assign(const value_type* __s, size_type __n);
-  _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string& assign(const value_type* __s);
+  _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string& assign(const value_type* __s, size_type __n)
+      _LIBCPP_DIAGNOSE_NULLPTR_IF(__n != 0 && __s == nullptr, " if n is not zero");
+  _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string& assign(const value_type* _LIBCPP_DIAGNOSE_NULLPTR __s);
   _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string& assign(size_type __n, value_type __c);
 
   template <class _InputIterator, __enable_if_t<__has_exactly_input_iterator_category<_InputIterator>::value, int> = 0>
@@ -1593,7 +1597,8 @@ public:
 
   _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string&
   insert(size_type __pos1, const basic_string& __str, size_type __pos2, size_type __n = npos);
-  _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string& insert(size_type __pos, const value_type* __s, size_type __n);
+  _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string& insert(size_type __pos, const value_type* __s, size_type __n)
+      _LIBCPP_DIAGNOSE_NULLPTR_IF(__n != 0 && __s == nullptr, " if n is not zero");
   _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string& insert(size_type __pos, const value_type* _LIBCPP_DIAGNOSE_NULLPTR __s);
   _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string& insert(size_type __pos, size_type __n, value_type __c);
   _LIBCPP_CONSTEXPR_SINCE_CXX20 iterator insert(const_iterator __pos, value_type __c);
@@ -1673,8 +1678,10 @@ public:
   }
 
   _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string&
-  replace(size_type __pos, size_type __n1, const value_type* __s, size_type __n2);
-  _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string& replace(size_type __pos, size_type __n1, const value_type* __s);
+  replace(size_type __pos, size_type __n1, const value_type* __s, size_type __n2)
+      _LIBCPP_DIAGNOSE_NULLPTR_IF(__n2 != 0 && __s == nullptr, " if n2 is not zero");
+  _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string&
+  replace(size_type __pos, size_type __n1, const value_type* _LIBCPP_DIAGNOSE_NULLPTR __s);
   _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string& replace(size_type __pos, size_type __n1, size_type __n2, value_type __c);
 
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string&
@@ -1783,7 +1790,8 @@ public:
     return std::__str_find<value_type, size_type, traits_type, npos>(data(), size(), __sv.data(), __pos, __sv.size());
   }
 
-  _LIBCPP_CONSTEXPR_SINCE_CXX20 size_type find(const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT {
+  _LIBCPP_CONSTEXPR_SINCE_CXX20 size_type find(const value_type* __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::find(): received nullptr");
     return std::__str_find<value_type, size_type, traits_type, npos>(data(), size(), __s, __pos, __n);
   }
@@ -1814,7 +1822,8 @@ public:
     return std::__str_rfind<value_type, size_type, traits_type, npos>(data(), size(), __sv.data(), __pos, __sv.size());
   }
 
-  _LIBCPP_CONSTEXPR_SINCE_CXX20 size_type rfind(const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT {
+  _LIBCPP_CONSTEXPR_SINCE_CXX20 size_type rfind(const value_type* __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::rfind(): received nullptr");
     return std::__str_rfind<value_type, size_type, traits_type, npos>(data(), size(), __s, __pos, __n);
   }
@@ -1847,7 +1856,8 @@ public:
   }
 
   _LIBCPP_CONSTEXPR_SINCE_CXX20 size_type
-  find_first_of(const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT {
+  find_first_of(const value_type* __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::find_first_of(): received nullptr");
     return std::__str_find_first_of<value_type, size_type, traits_type, npos>(data(), size(), __s, __pos, __n);
   }
@@ -1881,7 +1891,8 @@ public:
   }
 
   _LIBCPP_CONSTEXPR_SINCE_CXX20 size_type
-  find_last_of(const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT {
+  find_last_of(const value_type* __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::find_last_of(): received nullptr");
     return std::__str_find_last_of<value_type, size_type, traits_type, npos>(data(), size(), __s, __pos, __n);
   }
@@ -1915,7 +1926,8 @@ public:
   }
 
   _LIBCPP_CONSTEXPR_SINCE_CXX20 size_type
-  find_first_not_of(const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT {
+  find_first_not_of(const value_type* __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::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);
   }
@@ -1949,7 +1961,8 @@ public:
   }
 
   _LIBCPP_CONSTEXPR_SINCE_CXX20 size_type
-  find_last_not_of(const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT {
+  find_last_not_of(const value_type* __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::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);
   }
@@ -2026,7 +2039,8 @@ public:
   }
 
   _LIBCPP_CONSTEXPR_SINCE_CXX20 int
-  compare(size_type __pos1, size_type __n1, const value_type* __s, size_type __n2) const;
+  compare(size_type __pos1, size_type __n1, const value_type* __s, size_type __n2) const
+      _LIBCPP_DIAGNOSE_NULLPTR_IF(__n2 != 0 && __s == nullptr, " if n2 is not zero");
 
   // starts_with
 
@@ -3564,7 +3578,8 @@ operator==(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
 
 template <class _CharT, class _Traits, class _Allocator>
 inline _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI bool
-operator==(const basic_string<_CharT, _Traits, _Allocator>& __lhs, const _CharT* __rhs) _NOEXCEPT {
+operator==(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
+           const _CharT* _LIBCPP_DIAGNOSE_NULLPTR __rhs) _NOEXCEPT {
   _LIBCPP_ASSERT_NON_NULL(__rhs != nullptr, "operator==(basic_string, char*): received nullptr");
 
   using _String = basic_string<_CharT, _Traits, _Allocator>;
diff --git a/libcxx/include/string_view b/libcxx/include/string_view
index 861187c0640e1..f86b2722aca6c 100644
--- a/libcxx/include/string_view
+++ b/libcxx/include/string_view
@@ -318,8 +318,8 @@ public:
   _LIBCPP_HIDE_FROM_ABI basic_string_view& operator=(const basic_string_view&) _NOEXCEPT = default;
 
   _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI basic_string_view(const _CharT* __s, size_type __len) _NOEXCEPT
-      : __data_(__s),
-        __size_(__len) {
+      _LIBCPP_DIAGNOSE_NULLPTR_IF(__len != 0 && __s == nullptr, " if len is not zero")
+      : __data_(__s), __size_(__len) {
 #  if _LIBCPP_STD_VER >= 14
     // Allocations must fit in `ptrdiff_t` for pointer arithmetic to work. If `__len` exceeds it, the input
     // range could not have been valid. Most likely the caller underflowed some arithmetic and inadvertently
@@ -352,7 +352,7 @@ public:
       : __data_(ranges::data(__r)), __size_(ranges::size(__r)) {}
 #  endif // _LIBCPP_STD_VER >= 23
 
-  _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI basic_string_view(const _CharT* __s)
+  _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI basic_string_view(const _CharT* _LIBCPP_DIAGNOSE_NULLPTR __s)
       : __data_(__s), __size_(std::__char_traits_length_checked<_Traits>(__s)) {}
 
 #  if _LIBCPP_STD_VER >= 23
@@ -483,17 +483,19 @@ public:
     return substr(__pos1, __n1).compare(__sv.substr(__pos2, __n2));
   }
 
-  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI int compare(const _CharT* __s) const _NOEXCEPT {
+  _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
-  compare(size_type __pos1, size_type __n1, const _CharT* __s) const {
+  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
-  compare(size_type __pos1, size_type __n1, const _CharT* __s, size_type __n2) const {
+  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));
   }
 
@@ -509,13 +511,14 @@ public:
   }
 
   _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
-  find(const _CharT* __s, size_type __pos, size_type __n) const _NOEXCEPT {
+  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
-  find(const _CharT* __s, size_type __pos = 0) const _NOEXCEPT {
+  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));
@@ -534,13 +537,14 @@ public:
   }
 
   _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
-  rfind(const _CharT* __s, size_type __pos, size_type __n) const _NOEXCEPT {
+  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
-  rfind(const _CharT* __s, size_type __pos = npos) const _NOEXCEPT {
+  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));
@@ -560,13 +564,14 @@ public:
   }
 
   _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
-  find_first_of(const _CharT* __s, size_type __pos, size_type __n) const _NOEXCEPT {
+  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
-  find_first_of(const _CharT* __s, size_type __pos = 0) const _NOEXCEPT {
+  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));
@@ -586,13 +591,14 @@ public:
   }
 
   _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
-  find_last_of(const _CharT* __s, size_type __pos, size_type __n) const _NOEXCEPT ...
[truncated]

ldionne

This is a nice QOI improvement!

libcxx/include/__config

nico · 2025-07-19T17:18:08Z

Is there a way to suppress this warning while fixing these diagnostic?

philnik777 · 2025-07-21T09:09:56Z

Is there a way to suppress this warning while fixing these diagnostic?

You should be able to use -Wno-nonnull (or the appropriate #pragma clang diagnostic). BTW, does this find actual bugs for you or are there false-positives I'm not aware of?

nico · 2025-07-21T18:59:47Z

You should be able to use -Wno-nonnull (or the appropriate #pragma clang diagnostic).

-Wno-nonnull will disable all Wnonnulls, not just the ones from libc++. If we use that, new violations might be introduced elsewhere while we clean up.

…but in this case, it fired just in one file and I had access to the build file of the target it was in, so -Wno-nonnull worked.

BTW, does this find actual bugs for you or are there false-positives I'm not aware of?

It was a true (but boring) positive: https://crbug.com/433273929

philnik777 force-pushed the diagnose_nullptrs branch 4 times, most recently from 8fa51be to 892f584 Compare July 16, 2025 13:45

philnik777 marked this pull request as ready for review July 16, 2025 14:07

philnik777 requested a review from a team as a code owner July 16, 2025 14:07

llvmbot added the libc++ libc++ C++ Standard Library. Not GNU libstdc++. Not libc++abi. label Jul 16, 2025

ldionne approved these changes Jul 16, 2025

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philnik777 force-pushed the diagnose_nullptrs branch 4 times, most recently from e85b465 to 8ffaa61 Compare July 19, 2025 07:48

[libc++] Diagnose passing null pointers to a bunch of APIs

de734de

philnik777 force-pushed the diagnose_nullptrs branch from 8ffaa61 to de734de Compare July 19, 2025 07:56

philnik777 merged commit b5348e7 into llvm:main Jul 19, 2025
65 of 72 checks passed

philnik777 deleted the diagnose_nullptrs branch July 19, 2025 09:12

This was referenced Jul 23, 2025

test abhinavgaba/llvm-project#2

Closed

Add dataFence plugin interface abhinavgaba/llvm-project#3

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mahesh-attarde pushed a commit to mahesh-attarde/llvm-project that referenced this pull request Jul 28, 2025

[libc++] Diagnose passing null pointers to a bunch of APIs (llvm#148585)

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[libc++] Diagnose passing null pointers to a bunch of APIs #148585

[libc++] Diagnose passing null pointers to a bunch of APIs #148585

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[libc++] Diagnose passing null pointers to a bunch of APIs #148585

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