diff --git a/stl/inc/__msvc_int128.hpp b/stl/inc/__msvc_int128.hpp
index 56b0b4371e6..0018edbf674 100644
--- a/stl/inc/__msvc_int128.hpp
+++ b/stl/inc/__msvc_int128.hpp
@@ -10,10 +10,11 @@
 #include <yvals_core.h>
 #if _STL_COMPILER_PREPROCESSOR
 #include <cstdint>
-#include _STL_INTRIN_HEADER
 #include <limits>
 #include <type_traits>
 
+#include _STL_INTRIN_HEADER
+
 #if _HAS_CXX20
 #include <bit>
 #include <compare>
diff --git a/stl/inc/bit b/stl/inc/bit
index b4ecd911d05..cf2e52705b8 100644
--- a/stl/inc/bit
+++ b/stl/inc/bit
@@ -12,11 +12,12 @@
 _EMIT_STL_WARNING(STL4038, "The contents of <bit> are available only with C++20 or later.");
 #else // ^^^ !_HAS_CXX20 / _HAS_CXX20 vvv
 
-#include _STL_INTRIN_HEADER
 #include <isa_availability.h>
 #include <limits>
 #include <type_traits>
 
+#include _STL_INTRIN_HEADER
+
 #pragma pack(push, _CRT_PACKING)
 #pragma warning(push, _STL_WARNING_LEVEL)
 #pragma warning(disable : _STL_DISABLED_WARNINGS)
diff --git a/stl/inc/charconv b/stl/inc/charconv
index c26313fb9b3..4393c7dd217 100644
--- a/stl/inc/charconv
+++ b/stl/inc/charconv
@@ -13,13 +13,14 @@
 _EMIT_STL_WARNING(STL4038, "The contents of <charconv> are available only with C++17 or later.");
 #else // ^^^ !_HAS_CXX17 / _HAS_CXX17 vvv
 #include <cstring>
-#include _STL_INTRIN_HEADER
 #include <xbit_ops.h>
 #include <xcharconv.h>
 #include <xcharconv_ryu.h>
 #include <xcharconv_tables.h>
 #include <xutility>
 
+#include _STL_INTRIN_HEADER
+
 #pragma pack(push, _CRT_PACKING)
 #pragma warning(push, _STL_WARNING_LEVEL)
 #pragma warning(disable : _STL_DISABLED_WARNINGS)
diff --git a/stl/inc/limits b/stl/inc/limits
index 01e0f119c50..3617866926e 100644
--- a/stl/inc/limits
+++ b/stl/inc/limits
@@ -11,10 +11,11 @@
 #include <cfloat>
 #include <climits>
 #include <cwchar>
-#include _STL_INTRIN_HEADER
 #include <isa_availability.h>
 #include <xstddef>
 
+#include _STL_INTRIN_HEADER
+
 // TRANSITION, GH-2129, move down to _Arm64_popcount
 #if (defined(_M_ARM64) || defined(_M_ARM64EC)) && !defined(_M_CEE_PURE) && !defined(__CUDACC__) \
     && !defined(__INTEL_COMPILER) && !defined(__clang__) // TRANSITION, LLVM-51488
diff --git a/stl/inc/memory_resource b/stl/inc/memory_resource
index 16d8d0c9756..b008571c42a 100644
--- a/stl/inc/memory_resource
+++ b/stl/inc/memory_resource
@@ -576,18 +576,18 @@ namespace pmr {
 
         void release() noexcept /* strengthened */ {
             lock_guard<mutex> _Guard{_Mtx};
-            this->unsynchronized_pool_resource::release();
+            unsynchronized_pool_resource::release();
         }
 
     protected:
         void* do_allocate(const size_t _Bytes, const size_t _Align) override {
             lock_guard<mutex> _Guard{_Mtx};
-            return this->unsynchronized_pool_resource::do_allocate(_Bytes, _Align);
+            return unsynchronized_pool_resource::do_allocate(_Bytes, _Align);
         }
 
         void do_deallocate(void* const _Ptr, const size_t _Bytes, const size_t _Align) override {
             lock_guard<mutex> _Guard{_Mtx};
-            this->unsynchronized_pool_resource::do_deallocate(_Ptr, _Bytes, _Align);
+            unsynchronized_pool_resource::do_deallocate(_Ptr, _Bytes, _Align);
         }
 
     private:
diff --git a/stl/inc/ranges b/stl/inc/ranges
index 66e94c498ad..5469647071b 100644
--- a/stl/inc/ranges
+++ b/stl/inc/ranges
@@ -3549,6 +3549,17 @@ namespace ranges {
         _EXPORT_STD inline constexpr _Drop_while_fn drop_while;
     } // namespace views
 
+#ifdef __clang__
+    template <class _Rng> // TRANSITION, LLVM-47414
+    concept _Can_const_join = forward_range<const _Rng> && is_reference_v<range_reference_t<const _Rng>>
+                           && input_range<range_reference_t<const _Rng>>;
+#endif // ^^^ workaround ^^^
+
+    template <class _Ty>
+    _NODISCARD constexpr _Ty& _As_lvalue(_Ty&& _Val) noexcept {
+        return static_cast<_Ty&>(_Val);
+    }
+
     _EXPORT_STD template <input_range _Vw>
         requires view<_Vw> && input_range<range_reference_t<_Vw>>
     class join_view;
@@ -3569,17 +3580,6 @@ namespace ranges {
         /* [[no_unique_address]] */ _Non_propagating_cache<_Cache_wrapper, false> _Inner{};
     };
 
-#ifdef __clang__
-    template <class _Rng> // TRANSITION, LLVM-47414
-    concept _Can_const_join = forward_range<const _Rng> && is_reference_v<range_reference_t<const _Rng>>
-                           && input_range<range_reference_t<const _Rng>>;
-#endif // ^^^ workaround ^^^
-
-    template <class _Ty>
-    _NODISCARD constexpr _Ty& _As_lvalue(_Ty&& _Val) noexcept {
-        return static_cast<_Ty&>(_Val);
-    }
-
     template <class _Vw>
         requires is_reference_v<range_reference_t<_Vw>>
     class _Join_view_base<_Vw> : public view_interface<join_view<_Vw>> {};
diff --git a/stl/inc/regex b/stl/inc/regex
index 4e7cc0036e0..aa1974d47e1 100644
--- a/stl/inc/regex
+++ b/stl/inc/regex
@@ -628,7 +628,7 @@ public:
     }
 
     void swap(sub_match& _Other) noexcept(_Is_nothrow_swappable<_BidIt>::value) {
-        this->_Mybase::swap(_Other);
+        _Mybase::swap(_Other);
         _STD swap(matched, _Other.matched);
     }
 
diff --git a/stl/inc/type_traits b/stl/inc/type_traits
index cd40abc7795..679c42f7a18 100644
--- a/stl/inc/type_traits
+++ b/stl/inc/type_traits
@@ -1610,7 +1610,7 @@ _CONSTEXPR17 auto invoke(_Callable&& _Obj, _Ty1&& _Arg1, _Types2&&... _Args2) no
     } else if constexpr (_Invoker1<_Callable, _Ty1>::_Strategy == _Invoker_strategy::_Pmd_refwrap) {
         return _Arg1.get().*_Obj;
     } else {
-        static_assert(_Invoker1<_Callable, _Ty1>::_Strategy == _Invoker_strategy::_Pmd_pointer, "bug in invoke");
+        _STL_INTERNAL_STATIC_ASSERT(_Invoker1<_Callable, _Ty1>::_Strategy == _Invoker_strategy::_Pmd_pointer);
         return (*static_cast<_Ty1&&>(_Arg1)).*_Obj;
     }
 }
diff --git a/stl/inc/xatomic.h b/stl/inc/xatomic.h
index d6924b29ff5..83ca9def6f8 100644
--- a/stl/inc/xatomic.h
+++ b/stl/inc/xatomic.h
@@ -9,9 +9,10 @@
 #include <yvals_core.h>
 #if _STL_COMPILER_PREPROCESSOR
 
-#include _STL_INTRIN_HEADER
 #include <type_traits>
 
+#include _STL_INTRIN_HEADER
+
 #pragma pack(push, _CRT_PACKING)
 #pragma warning(push, _STL_WARNING_LEVEL)
 #pragma warning(disable : _STL_DISABLED_WARNINGS)
diff --git a/stl/inc/xbit_ops.h b/stl/inc/xbit_ops.h
index d7075cc2980..a46e3cdfb9c 100644
--- a/stl/inc/xbit_ops.h
+++ b/stl/inc/xbit_ops.h
@@ -10,6 +10,7 @@
 #if _STL_COMPILER_PREPROCESSOR
 
 #include <cstdint>
+
 #include _STL_INTRIN_HEADER
 
 #pragma pack(push, _CRT_PACKING)
diff --git a/stl/inc/xcharconv_ryu.h b/stl/inc/xcharconv_ryu.h
index 70ab5338355..8a7d22910fb 100644
--- a/stl/inc/xcharconv_ryu.h
+++ b/stl/inc/xcharconv_ryu.h
@@ -1318,7 +1318,7 @@ _NODISCARD pair<_CharT*, errc> __to_chars(_CharT* const _First, _CharT* const _L
   chars_format _Fmt, const uint32_t __ieeeMantissa, const uint32_t __ieeeExponent) {
   // Step 5: Print the decimal representation.
   uint32_t _Output = __v.__mantissa;
-  int32_t _Ryu_exponent = __v.__exponent;
+  const int32_t _Ryu_exponent = __v.__exponent;
   const uint32_t __olength = __decimalLength9(_Output);
   int32_t _Scientific_exponent = _Ryu_exponent + static_cast<int32_t>(__olength) - 1;
 
@@ -1926,7 +1926,7 @@ _NODISCARD pair<_CharT*, errc> __to_chars(_CharT* const _First, _CharT* const _L
   chars_format _Fmt, const double __f) {
   // Step 5: Print the decimal representation.
   uint64_t _Output = __v.__mantissa;
-  int32_t _Ryu_exponent = __v.__exponent;
+  const int32_t _Ryu_exponent = __v.__exponent;
   const uint32_t __olength = __decimalLength17(_Output);
   int32_t _Scientific_exponent = _Ryu_exponent + static_cast<int32_t>(__olength) - 1;
 
diff --git a/stl/inc/xutility b/stl/inc/xutility
index 74782010400..13b78725526 100644
--- a/stl/inc/xutility
+++ b/stl/inc/xutility
@@ -375,7 +375,7 @@ struct _Ref_fn { // pass function object by value as a reference
 };
 
 template <class _Fn>
-constexpr auto _Pass_fn(_Fn& _Func) noexcept {
+_NODISCARD constexpr auto _Pass_fn(_Fn& _Func) noexcept {
     constexpr bool _Pass_by_value = conjunction_v<bool_constant<sizeof(_Fn) <= sizeof(void*)>,
         is_trivially_copy_constructible<_Fn>, is_trivially_destructible<_Fn>>;
     if constexpr (_Pass_by_value) {
diff --git a/stl/src/ppltasks.cpp b/stl/src/ppltasks.cpp
index de405dd6cfb..e1d4375f473 100644
--- a/stl/src/ppltasks.cpp
+++ b/stl/src/ppltasks.cpp
@@ -39,7 +39,9 @@ namespace Concurrency {
 #if (defined(_M_IX86) || defined(_M_X64)) && !defined(_CRT_APP)
             if (IsProcessorFeaturePresent(PF_FASTFAIL_AVAILABLE))
 #endif
+            {
                 __fastfail(FAST_FAIL_INVALID_ARG);
+            }
 
             std::terminate();
         }
diff --git a/stl/src/xmath.hpp b/stl/src/xmath.hpp
index 67528bdd35f..eafcb9cef1e 100644
--- a/stl/src/xmath.hpp
+++ b/stl/src/xmath.hpp
@@ -1,8 +1,8 @@
 // Copyright (c) Microsoft Corporation.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
-#ifndef _XMATH
-#define _XMATH
+#pragma once
+
 #include <cerrno>
 #include <cmath>
 #include <limits>
@@ -205,5 +205,3 @@ template <typename T>
 #ifndef _M_CEE_PURE
 #pragma float_control(pop)
 #endif
-
-#endif // _XMATH
diff --git a/stl/src/xmtx.hpp b/stl/src/xmtx.hpp
index 9380716a3c0..44eb904eba5 100644
--- a/stl/src/xmtx.hpp
+++ b/stl/src/xmtx.hpp
@@ -2,19 +2,13 @@
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
 #pragma once
-#ifndef _XMTX
-#define _XMTX
+
 #include <yvals.h>
 
 #include <cstdlib>
 
 #include <Windows.h>
 
-#pragma pack(push, _CRT_PACKING)
-#pragma warning(push, 3)
-#pragma push_macro("new")
-#undef new
-
 _EXTERN_C_UNLESS_PURE
 
 using _Rmtx = CRITICAL_SECTION;
@@ -33,8 +27,3 @@ _MRTIMP2 void __cdecl _Mtxunlock(_Rmtx*) noexcept;
 #endif // _M_CEE_PURE
 
 _END_EXTERN_C_UNLESS_PURE
-
-#pragma pop_macro("new")
-#pragma warning(pop)
-#pragma pack(pop)
-#endif // _XMTX