[libc++] Fix a few warnings in system headers with GCC

This isn't fixing all of them, but at least it's making some progress.

Differential Revision: https://reviews.llvm.org/D106283

Author: ldionne

libcxx/include/__config

@@ -531,7 +531,7 @@ typedef __char32_t char32_t;
 
 #define _LIBCPP_NORETURN __attribute__((noreturn))
 
-#if !__EXCEPTIONS
+#if !defined(__EXCEPTIONS)
 #  define _LIBCPP_NO_EXCEPTIONS
 #endif
 
@@ -1023,7 +1023,8 @@ typedef unsigned int   char32_t;
 #if defined(_LIBCPP_COMPILER_CLANG_BASED) || defined(_LIBCPP_COMPILER_GCC)
 #   define _LIBCPP_SUPPRESS_DEPRECATED_PUSH \
         _Pragma("GCC diagnostic push") \
-        _Pragma("GCC diagnostic ignored \"-Wdeprecated\"")
+        _Pragma("GCC diagnostic ignored \"-Wdeprecated\"") \
+        _Pragma("GCC diagnostic ignored \"-Wdeprecated-declarations\"")
 #   define _LIBCPP_SUPPRESS_DEPRECATED_POP \
         _Pragma("GCC diagnostic pop")
 #else

libcxx/include/__hash_table

@@ -741,9 +741,9 @@ public:
 private:
 #if _LIBCPP_DEBUG_LEVEL == 2
     _LIBCPP_INLINE_VISIBILITY
-    __hash_const_local_iterator(__next_pointer __node, size_t __bucket,
+    __hash_const_local_iterator(__next_pointer __node_ptr, size_t __bucket,
                                 size_t __bucket_count, const void* __c) _NOEXCEPT
-        : __node_(__node),
+        : __node_(__node_ptr),
           __bucket_(__bucket),
           __bucket_count_(__bucket_count)
         {
@@ -753,9 +753,9 @@ private:
         }
 #else
     _LIBCPP_INLINE_VISIBILITY
-    __hash_const_local_iterator(__next_pointer __node, size_t __bucket,
+    __hash_const_local_iterator(__next_pointer __node_ptr, size_t __bucket,
                                 size_t __bucket_count) _NOEXCEPT
-        : __node_(__node),
+        : __node_(__node_ptr),
           __bucket_(__bucket),
           __bucket_count_(__bucket_count)
         {

libcxx/include/__ranges/transform_view.h

@@ -360,7 +360,7 @@ class transform_view<_View, _Fn>::__sentinel {
   __sentinel() = default;
 
   _LIBCPP_HIDE_FROM_ABI
-  constexpr explicit __sentinel(sentinel_t<_Base> __end_) : __end_(__end_) {}
+  constexpr explicit __sentinel(sentinel_t<_Base> __end) : __end_(__end) {}
 
   // Note: `__i` should always be `__sentinel<false>`, but directly using
   // `__sentinel<false>` is ill-formed when `_Const` is false

libcxx/include/barrier

@@ -107,7 +107,6 @@ void __destroy_barrier_algorithm_base(__barrier_algorithm_base* __barrier);
 
 template<class _CompletionF>
 class __barrier_base {
-
     ptrdiff_t                                               __expected;
     unique_ptr<__barrier_algorithm_base,
                void (*)(__barrier_algorithm_base*)>         __base;
@@ -146,7 +145,7 @@ public:
     _LIBCPP_AVAILABILITY_SYNC _LIBCPP_INLINE_VISIBILITY
     void wait(arrival_token&& __old_phase) const
     {
-        auto const __test_fn = [=]() -> bool {
+        auto const __test_fn = [this, __old_phase]() -> bool {
             return __phase.load(memory_order_acquire) != __old_phase;
         };
         __libcpp_thread_poll_with_backoff(__test_fn, __libcpp_timed_backoff_policy());

libcxx/include/charconv

@@ -612,13 +612,13 @@ __from_chars_integral(const char* __first, const char* __last, _Tp& __value,
 
     return __subject_seq_combinator(
         __first, __last, __value,
-        [](const char* __p, const char* __last, _Tp& __value,
+        [](const char* __p, const char* __lastx, _Tp& __value,
            int __base) -> from_chars_result {
             using __tl = numeric_limits<_Tp>;
             auto __digits = __tl::digits / log2f(float(__base));
             _Tp __a = __in_pattern(*__p++, __base).__val, __b = 0;
 
-            for (int __i = 1; __p != __last; ++__i, ++__p)
+            for (int __i = 1; __p != __lastx; ++__i, ++__p)
             {
                 if (auto __c = __in_pattern(*__p, __base))
                 {
@@ -636,7 +636,7 @@ __from_chars_integral(const char* __first, const char* __last, _Tp& __value,
                     break;
             }
 
-            if (__p == __last || !__in_pattern(*__p, __base))
+            if (__p == __lastx || !__in_pattern(*__p, __base))
             {
                 if (__tl::max() - __a >= __b)
                 {

libcxx/include/cmath

@@ -621,7 +621,7 @@ _Fp __lerp(_Fp __a, _Fp __b, _Fp __t) noexcept {
 
     if (__t == 1) return __b;
     const _Fp __x = __a + __t * (__b - __a);
-    if (__t > 1 == __b > __a)
+    if ((__t > 1) == (__b > __a))
         return __b < __x ? __x : __b;
     else
         return __x < __b ? __x : __b;

libcxx/include/compare

@@ -449,7 +449,7 @@ __compute_comp_type(const _ClassifyCompCategory (&__types)[_Size]) {
   return _StrongOrd;
 }
 
-template <class ..._Ts>
+template <class ..._Ts, bool _False = false>
 constexpr auto __get_comp_type() {
   using _CCC = _ClassifyCompCategory;
   constexpr _CCC __type_kinds[] = {_StrongOrd, __type_to_enum<_Ts>()...};
@@ -463,7 +463,7 @@ constexpr auto __get_comp_type() {
   else if constexpr (_Cat == _StrongOrd)
     return strong_ordering::equivalent;
   else
-    static_assert(_Cat != _Cat, "unhandled case");
+    static_assert(_False, "unhandled case");
 }
 } // namespace __comp_detail
 

libcxx/include/memory

@@ -796,7 +796,7 @@ void __construct_backward_with_exception_guarantees(_Alloc&, _Tp* __begin1, _Tp*
     ptrdiff_t _Np = __end1 - __begin1;
     __end2 -= _Np;
     if (_Np > 0)
-        _VSTD::memcpy(__end2, __begin1, _Np * sizeof(_Tp));
+        _VSTD::memcpy(static_cast<void*>(__end2), static_cast<void const*>(__begin1), _Np * sizeof(_Tp));
 }
 
 struct __destruct_n

libcxx/include/random

@@ -1731,7 +1731,7 @@ struct __is_seed_sequence
 template <unsigned long long __a, unsigned long long __c,
           unsigned long long __m, unsigned long long _Mp,
           bool _MightOverflow = (__a != 0 && __m != 0 && __m-1 > (_Mp-__c)/__a),
-          bool _OverflowOK = ((__m|__m-1) > __m), // m = 2^n
+          bool _OverflowOK = ((__m | (__m-1)) > __m), // m = 2^n
           bool _SchrageOK = (__a != 0 && __m != 0 && __m % __a <= __m / __a)> // r <= q
 struct __lce_alg_picker
 {

libcxx/include/regex

@@ -2003,14 +2003,14 @@ class __l_anchor_multiline
 {
     typedef __owns_one_state<_CharT> base;
 
-    bool __multiline;
+    bool __multiline_;
 
 public:
     typedef _VSTD::__state<_CharT> __state;
 
     _LIBCPP_INLINE_VISIBILITY
     __l_anchor_multiline(bool __multiline, __node<_CharT>* __s)
-        : base(__s), __multiline(__multiline) {}
+        : base(__s), __multiline_(__multiline) {}
 
     virtual void __exec(__state&) const;
 };
@@ -2025,7 +2025,7 @@ __l_anchor_multiline<_CharT>::__exec(__state& __s) const
         __s.__do_ = __state::__accept_but_not_consume;
         __s.__node_ = this->first();
     }
-    else if (__multiline &&
+    else if (__multiline_ &&
              !__s.__at_first_ &&
              __is_eol(*_VSTD::prev(__s.__current_)))
     {
@@ -4574,7 +4574,7 @@ basic_regex<_CharT, _Traits>::__parse_character_escape(_ForwardIterator __first,
             if (__hd == -1)
                 __throw_regex_error<regex_constants::error_escape>();
             __sum = 16 * __sum + static_cast<unsigned>(__hd);
-            // drop through
+            // fallthrough
         case 'x':
             ++__first;
             if (__first == __last)