microsoft · dunhor · Dec 12, 2025 · Dec 12, 2025 · Dec 12, 2025 · Dec 17, 2025
diff --git a/.clang-tidy b/.clang-tidy
@@ -33,6 +33,7 @@ Checks:
 - -readability-magic-numbers # Maybe we can revisit later, but for now this is too noisy
 - -readability-named-parameter # Too noisy, negatively impacts the use of tag types, and generally not that useful of a check
 - -readability-qualified-auto # Changes 'auto' to 'auto*' for pointers... Not really all that useful and kind of annoying for HANDLE
+- -readability-use-concise-preprocessor-directives # Suggests 'elif(n)def' with >= C++23, but we need to support down to C++17 and there's no option to suppress
 CheckOptions:
   bugprone-empty-catch.IgnoreCatchWithKeywords: 'Fall through'
   misc-non-private-member-variables-in-classes.IgnoreClassesWithAllMemberVariablesBeingPublic: true # Makes this check more tolerable

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
@@ -47,6 +47,36 @@ jobs:
             exit /b 1
           )
 
+  clang-tidy:
+    name: Clang-Tidy Check
+    runs-on: windows-latest
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Install/Update Clang
+        shell: cmd
+        run: |
+          choco upgrade llvm -y
+          if %ERRORLEVEL% NEQ 0 exit /b %ERRORLEVEL%
+
+          REM This is somewhat of a hack... we want to use the path to LLVM instead of MSVC's LLVM installation, but
+          REM _only_ when we're actually building with Clang. This is taking advantage of the fact that we're only
+          REM setting this variable when 'matrix.compiler' is 'clang'.
+          echo C:\Program Files\LLVM\bin >> %GITHUB_PATH%
+
+      - name: Run Clang-Tidy
+        shell: cmd
+        run: |
+          call scripts\call-vcvars.cmd x64
+          if %ERRORLEVEL% NEQ 0 goto :eof
+
+          call scripts\init.cmd -c clang -b relwithdebinfo
+          if %ERRORLEVEL% NEQ 0 goto :eof
+
+          ninja -C build\clang-x64-relwithdebinfo run-clang-tidy
+
   build_and_test:
     name: Build and Test
     strategy:

diff --git a/CMakeLists.txt b/CMakeLists.txt
@@ -40,7 +40,7 @@ if (${WIL_BUILD_TESTS})
             DEPENDS witest.cpplatest # Clang needs the pch, otherwise it fails
             USES_TERMINAL # Otherwise, we don't get any output until the command is done, which takes _a while_
             WORKING_DIRECTORY ${PROJECT_SOURCE_DIR}
-            COMMAND clang-tidy -p ${PROJECT_BINARY_DIR}/compile_commands.json tests/*.cpp
+            COMMAND clang-tidy -p ${PROJECT_BINARY_DIR}/compile_commands.json --warnings-as-errors=* tests/*.cpp
             )
     endif()
 endif()

diff --git a/include/wil/com.h b/include/wil/com.h
@@ -542,7 +542,7 @@ class com_ptr_t
         // Prefast cannot see through the error policy + query_policy mapping and as a result fires 6388 and 28196 for this
         // function. Suppression is also not working. Wrapping this entire function in #pragma warning(disable: 6388 28196) does
         // not stop all of the prefast errors from being emitted.
-#if defined(_PREFAST_)
+#ifdef _PREFAST_
         *ptrResult = nullptr;
         return err_policy::HResult(E_NOINTERFACE);
 #else
@@ -579,7 +579,7 @@ class com_ptr_t
         // Prefast cannot see through the error policy + query_policy mapping and as a result and as a result fires 6388 and 28196
         // for this function. Suppression is also not working. Wrapping this entire function in #pragma warning(disable: 6388
         // 28196) does not stop the prefast errors from being emitted.
-#if defined(_PREFAST_)
+#ifdef _PREFAST_
         *ptrResult = nullptr;
         return err_policy::HResult(E_NOINTERFACE);
 #else
@@ -726,7 +726,7 @@ class com_ptr_t
             // Prefast cannot see through the error policy + query_policy mapping and as a result and as a result fires 6388 and
             // 28196 for this function. Suppression is also not working. Wrapping this entire function in #pragma warning(disable:
             // 6388 28196) does not stop the prefast errors from being emitted.
-#if defined(_PREFAST_)
+#ifdef _PREFAST_
             *ptrResult = nullptr;
             return err_policy::HResult(E_NOINTERFACE);
 #else
@@ -758,7 +758,7 @@ class com_ptr_t
             // Prefast cannot see through the error policy + query_policy mapping and as a result and as a result fires 6388 and
             // 28196 for this function. Suppression is also not working. Wrapping this entire function in #pragma warning(disable:
             // 6388 28196) does not stop the prefast errors from being emitted.
-#if defined(_PREFAST_)
+#ifdef _PREFAST_
             *ptrResult = nullptr;
             return err_policy::HResult(E_NOINTERFACE);
 #else

diff --git a/include/wil/common.h b/include/wil/common.h
@@ -68,7 +68,7 @@
 /// @endcond
 
 /// @cond
-#if defined(_MSVC_LANG)
+#ifdef _MSVC_LANG
 #define __WI_SUPPRESS_BREAKING_WARNINGS_S __pragma(warning(push)) __pragma(warning(disable : 4127 26498 4245 26814))
 #define __WI_SUPPRESS_BREAKING_WARNINGS_E __pragma(warning(pop))
 #define __WI_SUPPRESS_NULLPTR_ANALYSIS __pragma(warning(suppress : 28285 6504))
@@ -331,7 +331,7 @@ extern "C"
 #include "wistd_type_traits.h"
 
 //! This macro inserts ODR violation protection; the macro allows it to be compatible with straight "C" code
-#if defined(_MSC_VER)
+#ifdef _MSC_VER
 #define WI_ODR_PRAGMA(NAME, TOKEN) __pragma(detect_mismatch("ODR_violation_" NAME "_mismatch", TOKEN))
 #else
 #define WI_ODR_PRAGMA(NAME, TOKEN)
@@ -359,7 +359,7 @@ routines suddenly becoming available. */
 #endif
 
 /// @cond
-#if defined(WIL_EXCEPTION_MODE)
+#ifdef WIL_EXCEPTION_MODE
 static_assert(WIL_EXCEPTION_MODE <= 2, "Invalid exception mode");
 #elif !defined(WIL_LOCK_EXCEPTION_MODE)
 #define WIL_EXCEPTION_MODE 0 // default, can link exception-based and non-exception based libraries together
@@ -430,7 +430,7 @@ deduce whether or not the STL is available and can be safely used.
 /// @endcond
 
 // block for documentation only
-#if defined(WIL_DOXYGEN)
+#ifdef WIL_DOXYGEN
 /** This define can be explicitly set to disable exception usage within wil.
 Normally this define is never needed as the WIL_ENABLE_EXCEPTIONS macro is enabled automatically by looking
 at _CPPUNWIND.  If your code compiles with exceptions enabled, but does not want to enable the exception-based
@@ -632,7 +632,7 @@ namespace details
 
 //! @}      // group bitwise
 
-#if defined(WIL_DOXYGEN)
+#ifdef WIL_DOXYGEN
 /** This macro provides a C++ header with a guaranteed initialization function.
 Normally, were a global object's constructor used for this purpose, the optimizer/linker might throw
 the object away if it's unreferenced (which throws away the side-effects that the initialization function
@@ -657,7 +657,7 @@ desktop APIs.  Building this functionality as `#IFDEF`s within functions would c
 doing it with global function pointers and header initialization allows a runtime determination. */
 #define WI_HEADER_INITIALIZATION_FUNCTION(name, fn)
 #elif defined(_M_IX86) || defined(_M_IA64) || defined(_M_AMD64) || defined(_M_ARM) || defined(_M_ARM64)
-#if defined(_MSC_VER)
+#ifdef _MSC_VER
 #ifdef _M_IX86
 #define WI_HEADER_INITIALIZATION_FUNCTION(name, fn) \
     extern "C" \

diff --git a/include/wil/coroutine.h b/include/wil/coroutine.h
@@ -148,7 +148,7 @@
 
 // Detect which version of the coroutine standard we have.
 /// @cond
-#if defined(_RESUMABLE_FUNCTIONS_SUPPORTED)
+#ifdef _RESUMABLE_FUNCTIONS_SUPPORTED
 #include <experimental/coroutine>
 #define __WI_COROUTINE_NAMESPACE ::std::experimental
 #elif defined(__cpp_impl_coroutine)

diff --git a/include/wil/cppwinrt.h b/include/wil/cppwinrt.h
@@ -40,7 +40,7 @@ constexpr int version_from_string(const char* versionString)
     int result = 0;
     while ((*versionString >= '0') && (*versionString <= '9'))
     {
-        result = result * 10 + (*versionString - '0');
+        result = (result * 10) + (*versionString - '0');
         ++versionString;
     }
 

diff --git a/include/wil/cppwinrt_helpers.h b/include/wil/cppwinrt_helpers.h
@@ -39,7 +39,7 @@ template <typename Dispatcher>
 struct dispatcher_traits;
 } // namespace wil::details
 
-#if defined(_RESUMABLE_FUNCTIONS_SUPPORTED)
+#ifdef _RESUMABLE_FUNCTIONS_SUPPORTED
 #include <experimental/coroutine>
 namespace wil::details
 {

diff --git a/include/wil/network.h b/include/wil/network.h
@@ -87,7 +87,7 @@ namespace network
         return {};
     }
 
-#if defined(WIL_ENABLE_EXCEPTIONS)
+#ifdef WIL_ENABLE_EXCEPTIONS
     // Calls WSAStartup and throws on error; returns an RAII object that reverts
     WI_NODISCARD inline ::wil::network::unique_wsacleanup_call WSAStartup()
     {
@@ -173,7 +173,7 @@ namespace network
         explicit socket_address(const SOCKET_ADDRESS* addr) WI_NOEXCEPT;
         explicit socket_address(const IN_ADDR* addr, unsigned short port = 0) WI_NOEXCEPT;
         explicit socket_address(const IN6_ADDR* addr, unsigned short port = 0) WI_NOEXCEPT;
-#if defined(WIL_ENABLE_EXCEPTIONS)
+#ifdef WIL_ENABLE_EXCEPTIONS
         explicit socket_address(PCWSTR addr, unsigned short port = 0);
 #endif
 
@@ -202,7 +202,7 @@ namespace network
         void set_address(const IN_ADDR* addr) WI_NOEXCEPT;
         void set_address(const IN6_ADDR* addr) WI_NOEXCEPT;
 
-#if defined(WIL_ENABLE_EXCEPTIONS)
+#ifdef WIL_ENABLE_EXCEPTIONS
         void reset_address(SOCKET s);
         void reset_address(PCWSTR address);
         void reset_address(PCSTR address);
@@ -407,7 +407,7 @@ namespace network
     // not defining a type for ADDRINFOEXA as that type is formally __declspec(deprecated)
     using addr_infoex_iterator = addr_info_iterator_t<ADDRINFOEXW>;
 
-#if defined(WIL_ENABLE_EXCEPTIONS)
+#ifdef WIL_ENABLE_EXCEPTIONS
     // function to capture resolving IP addresses assigned to the local machine, throwing on error
     // returning an RAII object containing the results
     inline ::wil::unique_addrinfo resolve_name(PCWSTR name)
@@ -711,7 +711,7 @@ namespace network
         set_port(port);
     }
 
-#if defined(WIL_ENABLE_EXCEPTIONS)
+#ifdef WIL_ENABLE_EXCEPTIONS
     inline socket_address::socket_address(PCWSTR addr, unsigned short port)
     {
         reset_address(addr);
@@ -1020,7 +1020,7 @@ namespace network
         m_sockaddr.Ipv6.sin6_port = original_port;
     }
 
-#if defined(WIL_ENABLE_EXCEPTIONS)
+#ifdef WIL_ENABLE_EXCEPTIONS
     inline void socket_address::reset_address(SOCKET s)
     {
         THROW_IF_FAILED(reset_address_nothrow(s));
@@ -1176,7 +1176,7 @@ namespace network
     }
 
     // the Winsock headers require having set this #define to access ANSI-string versions of the Winsock API
-#if defined(_WINSOCK_DEPRECATED_NO_WARNINGS)
+#ifdef _WINSOCK_DEPRECATED_NO_WARNINGS
     inline HRESULT socket_address::format_complete_address_nothrow(socket_address_string& address) const WI_NOEXCEPT
     {
         ::memset(address, 0, sizeof(socket_address_string));

diff --git a/include/wil/registry.h b/include/wil/registry.h
@@ -31,7 +31,7 @@ namespace wil
 //! Functions and classes that support reading and writing values to/from the registry.
 namespace reg
 {
-#if defined(WIL_ENABLE_EXCEPTIONS)
+#ifdef WIL_ENABLE_EXCEPTIONS
     /**
      * @brief Opens a new HKEY to the specified path - see RegOpenKeyExW
      * @param key An open or well-known registry key
@@ -101,7 +101,7 @@ namespace reg
         return return_value;
     }
 #endif // #if defined(__WIL_WINREG_STL)
-#endif // #if defined(WIL_ENABLE_EXCEPTIONS)
+#endif // #ifdef WIL_ENABLE_EXCEPTIONS
 
     /**
      * @brief Opens a new HKEY to the specified path - see RegOpenKeyExW
@@ -221,7 +221,7 @@ namespace reg
     //         // the HRESULT last_error() returns the registry error that prevented enumeration
     //     }
     //
-#if defined(WIL_ENABLE_EXCEPTIONS)
+#ifdef WIL_ENABLE_EXCEPTIONS
 
 #if WIL_USE_STL || defined(WIL_DOXYGEN)
     using key_iterator = ::wil::reg::iterator_t<::wil::reg::key_iterator_data<::std::wstring>>;
@@ -236,7 +236,7 @@ namespace reg
     using key_heap_string_iterator = ::wil::reg::iterator_t<::wil::reg::key_iterator_data<::wil::unique_process_heap_string>>;
     using value_heap_string_iterator = ::wil::reg::iterator_t<::wil::reg::value_iterator_data<::wil::unique_process_heap_string>>;
 
-#endif // #if defined(WIL_ENABLE_EXCEPTIONS)
+#endif // #ifdef WIL_ENABLE_EXCEPTIONS
 
     // no-throw versions of applicable registry iterators
 #if defined(__WIL_OLEAUTO_H_) || defined(WIL_DOXYGEN)
@@ -337,7 +337,7 @@ namespace reg
         return S_OK;
     }
 
-#if defined(WIL_ENABLE_EXCEPTIONS)
+#ifdef WIL_ENABLE_EXCEPTIONS
     /**
      * @brief Queries for number of sub-keys
      * @param key The HKEY to query for number of sub-keys
@@ -376,9 +376,9 @@ namespace reg
         THROW_IF_FAILED(::wil::reg::get_last_write_filetime_nothrow(key, &lastModified));
         return lastModified;
     }
-#endif // #if defined(WIL_ENABLE_EXCEPTIONS)
+#endif // #ifdef WIL_ENABLE_EXCEPTIONS
 
-#if defined(WIL_ENABLE_EXCEPTIONS)
+#ifdef WIL_ENABLE_EXCEPTIONS
     //
     // template <typename T>
     // void set_value(...)
@@ -920,7 +920,7 @@ namespace reg
     }
 #endif
 
-#if defined(WIL_ENABLE_EXCEPTIONS)
+#ifdef WIL_ENABLE_EXCEPTIONS
     //
     // template <typename T>
     // T get_value(...)
@@ -1720,14 +1720,14 @@ namespace reg
     template <typename T>
     ::std::optional<T> try_get_value(HKEY key, _In_opt_ PCWSTR subkey, _In_opt_ PCWSTR value_name)
     {
-#if defined(__WIL_OLEAUTO_H_)
+#ifdef __WIL_OLEAUTO_H_
         // not allowing unique types with try_get_value: wil::unique_bstr cannot be copied and thus is difficult to work with a std::optional
         static_assert(!wistd::is_same_v<T, ::wil::unique_bstr>, "try_get with wil::unique_bstr is disabled");
-#endif // #if defined(__WIL_OLEAUTO_H_)
-#if defined(__WIL_OBJBASE_H_)
+#endif // #ifdef __WIL_OLEAUTO_H_
+#ifdef __WIL_OBJBASE_H_
         // not allowing unique types with try_get_value: wil::unique_cotaskmem_string cannot be copied and thus is difficult to work with a std::optional
         static_assert(!wistd::is_same_v<T, ::wil::unique_cotaskmem_string>, "try_get with wil::unique_cotaskmem_string is disabled");
-#endif // #if defined(__WIL_OBJBASE_H_)
+#endif // #ifdef __WIL_OBJBASE_H_
 
         const reg_view_details::reg_view regview{key};
         return regview.try_get_value<T>(subkey, value_name);
@@ -1747,14 +1747,14 @@ namespace reg
     template <typename T>
     ::std::optional<T> try_get_value(HKEY key, _In_opt_ PCWSTR value_name)
     {
-#if defined(__WIL_OLEAUTO_H_)
+#ifdef __WIL_OLEAUTO_H_
         // not allowing unique types with try_get_value: wil::unique_bstr cannot be copied and thus is difficult to work with a std::optional
         static_assert(!wistd::is_same_v<T, ::wil::unique_bstr>, "try_get with wil::unique_bstr is disabled");
-#endif // #if defined(__WIL_OLEAUTO_H_)
-#if defined(__WIL_OBJBASE_H_)
+#endif // #ifdef __WIL_OLEAUTO_H_
+#ifdef __WIL_OBJBASE_H_
         // not allowing unique types with try_get_value: wil::unique_cotaskmem_string cannot be copied and thus is difficult to work with a std::optional
         static_assert(!wistd::is_same_v<T, ::wil::unique_cotaskmem_string>, "try_get with wil::unique_cotaskmem_string is disabled");
-#endif // #if defined(__WIL_OBJBASE_H_)
+#endif // #ifdef __WIL_OBJBASE_H_
 
         return ::wil::reg::try_get_value<T>(key, nullptr, value_name);
     }