Simplify away _STL_WIN32_WINNT machinery for bincompat functions

CMakeLists.txt

@@ -58,25 +58,18 @@ if("${VCLIBS_TARGET_ARCHITECTURE}" STREQUAL "x86")
     set(VCLIBS_TARGET_ARCHITECTURE "x86")
     set(VCLIBS_I386_OR_AMD64 "i386")
     set(VCLIBS_X86_OR_X64 "x86")
-
-    # Note that we set _WIN32_WINNT to a high level to make declarations available, but still engage downlevel
-    # runtime dynamic linking by setting our own _STL_WIN32_WINNT back to Windows XP.
-    add_compile_definitions(_X86_ _VCRT_WIN32_WINNT=0x0501 _STL_WIN32_WINNT=0x0501)
 elseif(VCLIBS_TARGET_ARCHITECTURE STREQUAL "x64")
     set(VCLIBS_TARGET_ARCHITECTURE "x64")
     set(VCLIBS_I386_OR_AMD64 "amd64")
     set(VCLIBS_X86_OR_X64 "x64")
-    add_compile_definitions(_AMD64_ _VCRT_WIN32_WINNT=0x0501 _STL_WIN32_WINNT=0x0501)
 elseif(VCLIBS_TARGET_ARCHITECTURE STREQUAL "arm64")
     set(VCLIBS_TARGET_ARCHITECTURE "arm64")
     set(VCLIBS_I386_OR_AMD64 "arm64")
     set(VCLIBS_X86_OR_X64 "arm64")
-    add_compile_definitions(_ARM64_ _VCRT_WIN32_WINNT=0x0A00 _STL_WIN32_WINNT=0x0A00)
 elseif(VCLIBS_TARGET_ARCHITECTURE STREQUAL "arm64ec")
     set(VCLIBS_TARGET_ARCHITECTURE "arm64ec")
     set(VCLIBS_I386_OR_AMD64 "arm64ec")
     set(VCLIBS_X86_OR_X64 "arm64") # Yes, really: `%VCToolsInstallDir%lib\arm64ec` only contains the Link Options
-    add_compile_definitions(_AMD64_ _ARM64EC_ _VCRT_WIN32_WINNT=0x0501 _STL_WIN32_WINNT=0x0501)
     add_compile_options($<$<COMPILE_LANGUAGE:CXX>:/arm64EC>)
     set(VCLIBS_EXPLICIT_MACHINE "/machine:arm64ec")
 else()
@@ -92,6 +85,7 @@ set(STL_ARCHIVE_OUTPUT_DIRECTORY "${PROJECT_BINARY_DIR}/out/lib/${VCLIBS_I386_OR
 set(STL_LIBRARY_OUTPUT_DIRECTORY "${PROJECT_BINARY_DIR}/out/lib/${VCLIBS_I386_OR_AMD64}")
 set(STL_RUNTIME_OUTPUT_DIRECTORY "${PROJECT_BINARY_DIR}/out/bin/${VCLIBS_I386_OR_AMD64}")
 
+# Note that we set _WIN32_WINNT to a high level to make declarations available.
 add_compile_definitions(
     _ALLOW_ITERATOR_DEBUG_LEVEL_MISMATCH WIN32_LEAN_AND_MEAN STRICT _CRT_STDIO_ARBITRARY_WIDE_SPECIFIERS
     _WIN32_WINNT=0x0A00 NTDDI_VERSION=NTDDI_WIN11_GE)

stl/inc/yvals_core.h

@@ -1955,14 +1955,7 @@ _EMIT_STL_ERROR(STL1013, "The STL doesn't support /RTCc because it rejects confo
 #error In yvals_core.h, defined(MRTDLL) implies defined(_M_CEE_PURE); !defined(_M_CEE_PURE) implies !defined(MRTDLL)
 #endif // defined(MRTDLL) && !defined(_M_CEE_PURE)
 
-#define _STL_WIN32_WINNT_VISTA 0x0600 // _WIN32_WINNT_VISTA from sdkddkver.h
-#define _STL_WIN32_WINNT_WIN10 0x0A00 // _WIN32_WINNT_WIN10 from sdkddkver.h
-
-// Note that the STL DLL builds will set this to XP for ABI compatibility with VS2015 which supported XP.
-#ifndef _STL_WIN32_WINNT
-// The earliest Windows supported by this implementation is Windows 10
-#define _STL_WIN32_WINNT _STL_WIN32_WINNT_WIN10
-#endif // !defined(_STL_WIN32_WINNT)
+// The earliest Windows supported by this implementation is Windows 10.
 
 #ifdef __cpp_noexcept_function_type
 #define _NOEXCEPT_FNPTR           noexcept

stl/src/atomic.cpp

@@ -5,7 +5,7 @@
 
 #include <yvals.h>
 
-#include <synchapi.h>
+#include <Windows.h>
 
 namespace {
     SRWLOCK _Shared_ptr_lock = SRWLOCK_INIT;

stl/src/sharedmutex.cpp

@@ -2,7 +2,8 @@
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
 #include <__msvc_threads_core.hpp>
-#include <synchapi.h>
+
+#include <Windows.h>
 
 #include "primitives.hpp"
 

stl/src/winapinls.cpp

@@ -1,9 +1,11 @@
 // Copyright (c) Microsoft Corporation.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
-#include <yvals_core.h>
-
-#if _STL_WIN32_WINNT < _STL_WIN32_WINNT_VISTA
+// Previously, x64/x86 Desktop builds had to support targeting old versions of Windows, so we dllexported functions to
+// dynamically load new Windows APIs. Now, we directly call those Windows APIs, and the dllexported functions have
+// become simple wrappers, but they still need to be preserved for binary compatibility. The ARM64, App, and OneCore
+// builds never supported targeting old versions of Windows, so they never provided these dllexported functions.
+#if !(defined(_M_ARM64) || defined(_CRT_APP) || defined(_ONECORE))
 
 #include <yvals.h>
 
@@ -29,4 +31,4 @@ extern "C" _CRTIMP2 int __cdecl __crtGetLocaleInfoEx(_In_opt_ LPCWSTR const lpLo
     return GetLocaleInfoEx(lpLocaleName, LCType, lpLCData, cchData);
 }
 
-#endif // _STL_WIN32_WINNT < _STL_WIN32_WINNT_VISTA
+#endif // ^^^ !(defined(_M_ARM64) || defined(_CRT_APP) || defined(_ONECORE)) ^^^

stl/src/winapisupp.cpp

@@ -35,7 +35,11 @@ extern "C" _CRTIMP2 BOOL __cdecl __crtIsPackagedApp() noexcept {
 
 #endif // !defined(_CRT_WINDOWS) && !defined(UNDOCKED_WINDOWS_UCRT)
 
-#if _STL_WIN32_WINNT < _WIN32_WINNT_VISTA
+// Previously, x64/x86 Desktop builds had to support targeting old versions of Windows, so we dllexported functions to
+// dynamically load new Windows APIs. Now, we directly call those Windows APIs, and the dllexported functions have
+// become simple wrappers, but they still need to be preserved for binary compatibility. The ARM64, App, and OneCore
+// builds never supported targeting old versions of Windows, so they never provided these dllexported functions.
+#if !(defined(_M_ARM64) || defined(_CRT_APP) || defined(_ONECORE))
 
 // TRANSITION, ABI: preserved for binary compatibility
 extern "C" _CRTIMP2 ULONGLONG __cdecl __crtGetTickCount64() noexcept {
@@ -150,16 +154,13 @@ extern "C" _CRTIMP2 BOOL __cdecl __crtSetFileInformationByHandle(_In_ HANDLE con
     _In_reads_bytes_(dwBufferSize) LPVOID const lpFileInformation, _In_ DWORD const dwBufferSize) noexcept {
     return SetFileInformationByHandle(hFile, FileInformationClass, lpFileInformation, dwBufferSize);
 }
-#endif // _STL_WIN32_WINNT < _WIN32_WINNT_VISTA
-
-#if _STL_WIN32_WINNT < _WIN32_WINNT_WIN8
 
 // TRANSITION, ABI: preserved for binary compatibility
 extern "C" _CRTIMP2 void __cdecl __crtGetSystemTimePreciseAsFileTime(_Out_ LPFILETIME lpSystemTimeAsFileTime) noexcept {
     GetSystemTimePreciseAsFileTime(lpSystemTimeAsFileTime);
 }
 
-#endif // _STL_WIN32_WINNT < _WIN32_WINNT_WIN8
+#endif // ^^^ !(defined(_M_ARM64) || defined(_CRT_APP) || defined(_ONECORE)) ^^^
 
 extern "C" _Success_(return > 0 && return < BufferLength) DWORD __stdcall __crtGetTempPath2W(
     _In_ DWORD BufferLength, _Out_writes_to_opt_(BufferLength, return +1) LPWSTR Buffer) noexcept {

stl/src/xonce2.cpp

@@ -4,7 +4,8 @@
 #include <yvals_core.h>
 
 #include <cstdlib>
-#include <synchapi.h>
+
+#include <Windows.h>
 
 // Provides forwarders for InitOnceBeginInitialize and InitOnceComplete for
 // environments that can't use /ALTERNATENAME.