[libc++][hardening] Categorize more assertions. (#75918)

Also introduce `_LIBCPP_ASSERT_PEDANTIC` for assertions violating which
results in a no-op or other benign behavior, but which may nevertheless
indicate a bug in the invoking code.

Author: var-const

libcxx/include/__algorithm/pop_heap.h

@@ -36,7 +36,8 @@ __pop_heap(_RandomAccessIterator __first,
            _RandomAccessIterator __last,
            _Compare& __comp,
            typename iterator_traits<_RandomAccessIterator>::difference_type __len) {
-  _LIBCPP_ASSERT_UNCATEGORIZED(__len > 0, "The heap given to pop_heap must be non-empty");
+  // Calling `pop_heap` on an empty range is undefined behavior, but in practice it will be a no-op.
+  _LIBCPP_ASSERT_PEDANTIC(__len > 0, "The heap given to pop_heap must be non-empty");
 
   __comp_ref_type<_Compare> __comp_ref = __comp;
 

libcxx/include/__algorithm/sift_down.h

@@ -85,7 +85,7 @@ _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _RandomAccessIterator __floy
     _Compare&& __comp,
     typename iterator_traits<_RandomAccessIterator>::difference_type __len) {
   using difference_type = typename iterator_traits<_RandomAccessIterator>::difference_type;
-  _LIBCPP_ASSERT_UNCATEGORIZED(__len >= 2, "shouldn't be called unless __len >= 2");
+  _LIBCPP_ASSERT_INTERNAL(__len >= 2, "shouldn't be called unless __len >= 2");
 
   _RandomAccessIterator __hole    = __first;
   _RandomAccessIterator __child_i = __first;

libcxx/include/__algorithm/sort.h

@@ -533,7 +533,7 @@ __bitset_partition(_RandomAccessIterator __first, _RandomAccessIterator __last,
   using _Ops = _IterOps<_AlgPolicy>;
   typedef typename std::iterator_traits<_RandomAccessIterator>::value_type value_type;
   typedef typename std::iterator_traits<_RandomAccessIterator>::difference_type difference_type;
-  _LIBCPP_ASSERT_UNCATEGORIZED(__last - __first >= difference_type(3), "");
+  _LIBCPP_ASSERT_INTERNAL(__last - __first >= difference_type(3), "");
   const _RandomAccessIterator __begin = __first; // used for bounds checking, those are not moved around
   const _RandomAccessIterator __end   = __last;
   (void)__end; //
@@ -625,7 +625,7 @@ __partition_with_equals_on_right(_RandomAccessIterator __first, _RandomAccessIte
   using _Ops = _IterOps<_AlgPolicy>;
   typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
   typedef typename std::iterator_traits<_RandomAccessIterator>::value_type value_type;
-  _LIBCPP_ASSERT_UNCATEGORIZED(__last - __first >= difference_type(3), "");
+  _LIBCPP_ASSERT_INTERNAL(__last - __first >= difference_type(3), "");
   const _RandomAccessIterator __begin = __first; // used for bounds checking, those are not moved around
   const _RandomAccessIterator __end   = __last;
   (void)__end; //

libcxx/include/__charconv/to_chars_base_10.h

@@ -132,14 +132,14 @@ __base_10_u64(char* __buffer, uint64_t __value) noexcept {
 /// range that can be used. However the range is sufficient for
 /// \ref __base_10_u128.
 _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI inline __uint128_t __pow_10(int __exp) noexcept {
-  _LIBCPP_ASSERT_UNCATEGORIZED(__exp >= __pow10_128_offset, "Index out of bounds");
+  _LIBCPP_ASSERT_INTERNAL(__exp >= __pow10_128_offset, "Index out of bounds");
   return __pow10_128[__exp - __pow10_128_offset];
 }
 
 _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI inline char*
 __base_10_u128(char* __buffer, __uint128_t __value) noexcept {
-  _LIBCPP_ASSERT_UNCATEGORIZED(
-      __value > numeric_limits<uint64_t>::max(), "The optimizations for this algorithm fail when this isn't true.");
+  _LIBCPP_ASSERT_INTERNAL(
+      __value > numeric_limits<uint64_t>::max(), "The optimizations for this algorithm fails when this isn't true.");
 
   // Unlike the 64 to 32 bit case the 128 bit case the "upper half" can't be
   // stored in the "lower half". Instead we first need to handle the top most

libcxx/include/__charconv/to_chars_integral.h

@@ -246,7 +246,7 @@ __to_chars_integral(char* __first, char* __last, _Tp __value) {
 
 template <typename _Tp>
 _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI int __to_chars_integral_width(_Tp __value, unsigned __base) {
-  _LIBCPP_ASSERT_UNCATEGORIZED(__value >= 0, "The function requires a non-negative value.");
+  _LIBCPP_ASSERT_INTERNAL(__value >= 0, "The function requires a non-negative value.");
 
   unsigned __base_2 = __base * __base;
   unsigned __base_3 = __base_2 * __base;

libcxx/include/__charconv/traits.h

@@ -101,11 +101,11 @@ struct _LIBCPP_HIDDEN __traits_base<_Tp, __enable_if_t<sizeof(_Tp) == sizeof(__u
   /// zero is set to one. This means the first element of the lookup table is
   /// zero.
   static _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI int __width(_Tp __v) {
-    _LIBCPP_ASSERT_UNCATEGORIZED(
+    _LIBCPP_ASSERT_INTERNAL(
         __v > numeric_limits<uint64_t>::max(), "The optimizations for this algorithm fail when this isn't true.");
     // There's always a bit set in the upper 64-bits.
     auto __t = (128 - std::__libcpp_clz(static_cast<uint64_t>(__v >> 64))) * 1233 >> 12;
-    _LIBCPP_ASSERT_UNCATEGORIZED(__t >= __itoa::__pow10_128_offset, "Index out of bounds");
+    _LIBCPP_ASSERT_INTERNAL(__t >= __itoa::__pow10_128_offset, "Index out of bounds");
     // __t is adjusted since the lookup table misses the lower entries.
     return __t - (__v < __itoa::__pow10_128[__t - __itoa::__pow10_128_offset]) + 1;
   }

libcxx/include/__chrono/parser_std_format_spec.h

@@ -160,10 +160,9 @@ class _LIBCPP_TEMPLATE_VIS __parser_chrono {
 private:
   _LIBCPP_HIDE_FROM_ABI constexpr _ConstIterator
   __parse_chrono_specs(_ConstIterator __begin, _ConstIterator __end, __flags __flags) {
-    _LIBCPP_ASSERT_UNCATEGORIZED(
-        __begin != __end,
-        "When called with an empty input the function will cause "
-        "undefined behavior by evaluating data not in the input");
+    _LIBCPP_ASSERT_INTERNAL(__begin != __end,
+                            "When called with an empty input the function will cause "
+                            "undefined behavior by evaluating data not in the input");
 
     if (*__begin != _CharT('%') && *__begin != _CharT('}'))
       std::__throw_format_error("The format specifier expects a '%' or a '}'");

libcxx/include/__config

@@ -283,6 +283,9 @@
 // - `_LIBCPP_ASSERT_COMPATIBLE_ALLOCATOR` -- checks any operations that exchange nodes between containers to make sure
 //   the containers have compatible allocators.
 //
+// - `_LIBCPP_ASSERT_PEDANTIC` -- checks prerequisites which are imposed by the Standard, but violating which happens to
+//   be benign in our implementation.
+//
 // - `_LIBCPP_ASSERT_INTERNAL` -- checks that internal invariants of the library hold. These assertions don't depend on
 //   user input.
 //
@@ -325,6 +328,7 @@ _LIBCPP_HARDENING_MODE_DEBUG
 // vulnerability.
 #    define _LIBCPP_ASSERT_NON_OVERLAPPING_RANGES(expression, message)   _LIBCPP_ASSUME(expression)
 #    define _LIBCPP_ASSERT_COMPATIBLE_ALLOCATOR(expression, message)     _LIBCPP_ASSUME(expression)
+#    define _LIBCPP_ASSERT_PEDANTIC(expression, message)                 _LIBCPP_ASSUME(expression)
 #    define _LIBCPP_ASSERT_INTERNAL(expression, message)                 _LIBCPP_ASSUME(expression)
 #    define _LIBCPP_ASSERT_UNCATEGORIZED(expression, message)            _LIBCPP_ASSUME(expression)
 
@@ -339,6 +343,7 @@ _LIBCPP_HARDENING_MODE_DEBUG
 #    define _LIBCPP_ASSERT_NON_OVERLAPPING_RANGES(expression, message)   _LIBCPP_ASSERT(expression, message)
 #    define _LIBCPP_ASSERT_COMPATIBLE_ALLOCATOR(expression, message)     _LIBCPP_ASSERT(expression, message)
 #    define _LIBCPP_ASSERT_UNCATEGORIZED(expression, message)            _LIBCPP_ASSERT(expression, message)
+#    define _LIBCPP_ASSERT_PEDANTIC(expression, message)                 _LIBCPP_ASSERT(expression, message)
 // Disabled checks.
 #    define _LIBCPP_ASSERT_INTERNAL(expression, message)                 _LIBCPP_ASSUME(expression)
 
@@ -352,6 +357,7 @@ _LIBCPP_HARDENING_MODE_DEBUG
 #    define _LIBCPP_ASSERT_NON_NULL(expression, message)                  _LIBCPP_ASSERT(expression, message)
 #    define _LIBCPP_ASSERT_NON_OVERLAPPING_RANGES(expression, message)    _LIBCPP_ASSERT(expression, message)
 #    define _LIBCPP_ASSERT_COMPATIBLE_ALLOCATOR(expression, message)      _LIBCPP_ASSERT(expression, message)
+#    define _LIBCPP_ASSERT_PEDANTIC(expression, message)                  _LIBCPP_ASSERT(expression, message)
 #    define _LIBCPP_ASSERT_INTERNAL(expression, message)                  _LIBCPP_ASSERT(expression, message)
 #    define _LIBCPP_ASSERT_UNCATEGORIZED(expression, message)             _LIBCPP_ASSERT(expression, message)
 
@@ -365,6 +371,7 @@ _LIBCPP_HARDENING_MODE_DEBUG
 #    define _LIBCPP_ASSERT_NON_NULL(expression, message)                  _LIBCPP_ASSUME(expression)
 #    define _LIBCPP_ASSERT_NON_OVERLAPPING_RANGES(expression, message)    _LIBCPP_ASSUME(expression)
 #    define _LIBCPP_ASSERT_COMPATIBLE_ALLOCATOR(expression, message)      _LIBCPP_ASSUME(expression)
+#    define _LIBCPP_ASSERT_PEDANTIC(expression, message)                  _LIBCPP_ASSUME(expression)
 #    define _LIBCPP_ASSERT_INTERNAL(expression, message)                  _LIBCPP_ASSUME(expression)
 #    define _LIBCPP_ASSERT_UNCATEGORIZED(expression, message)             _LIBCPP_ASSUME(expression)
 

libcxx/include/__filesystem/directory_iterator.h

@@ -73,7 +73,8 @@ class directory_iterator {
   _LIBCPP_HIDE_FROM_ABI ~directory_iterator() = default;
 
   _LIBCPP_HIDE_FROM_ABI const directory_entry& operator*() const {
-    _LIBCPP_ASSERT_UNCATEGORIZED(__imp_, "The end iterator cannot be dereferenced");
+    // Note: this check duplicates a check in `__dereference()`.
+    _LIBCPP_ASSERT_NON_NULL(__imp_, "The end iterator cannot be dereferenced");
     return __dereference();
   }
 

libcxx/include/__filesystem/path_iterator.h

@@ -61,7 +61,7 @@ class _LIBCPP_EXPORTED_FROM_ABI path::iterator {
   _LIBCPP_HIDE_FROM_ABI pointer operator->() const { return &__stashed_elem_; }
 
   _LIBCPP_HIDE_FROM_ABI iterator& operator++() {
-    _LIBCPP_ASSERT_UNCATEGORIZED(__state_ != _Singular, "attempting to increment a singular iterator");
+    _LIBCPP_ASSERT_NON_NULL(__state_ != _Singular, "attempting to increment a singular iterator");
     _LIBCPP_ASSERT_UNCATEGORIZED(__state_ != _AtEnd, "attempting to increment the end iterator");
     return __increment();
   }
@@ -73,7 +73,7 @@ class _LIBCPP_EXPORTED_FROM_ABI path::iterator {
   }
 
   _LIBCPP_HIDE_FROM_ABI iterator& operator--() {
-    _LIBCPP_ASSERT_UNCATEGORIZED(__state_ != _Singular, "attempting to decrement a singular iterator");
+    _LIBCPP_ASSERT_NON_NULL(__state_ != _Singular, "attempting to decrement a singular iterator");
     _LIBCPP_ASSERT_UNCATEGORIZED(
         __entry_.data() != __path_ptr_->native().data(), "attempting to decrement the begin iterator");
     return __decrement();