From ed0f48e79bd7cffe1fcc18cc6b8539219f14f6d6 Mon Sep 17 00:00:00 2001
From: Nilsen84 <166841-Nilsen84@users.noreply.gitlab.kitware.com>
Date: Fri, 13 Feb 2026 13:44:45 +0100
Subject: [PATCH] clang-cl: use gcc depfiles over /showIncludes

This enables `#embed` dependencies when using `clang-cl`.

Fixes: #27594
---
 Modules/Compiler/Clang-C.cmake              |  5 -----
 Modules/Compiler/Clang-CXX.cmake            |  5 -----
 Modules/Platform/Windows-Clang-C.cmake      | 20 ++++++--------------
 Modules/Platform/Windows-Clang-CXX.cmake    | 20 ++++++--------------
 Modules/Platform/Windows-Clang-HIP.cmake    | 20 ++++++--------------
 Modules/Platform/Windows-Clang-OBJC.cmake   | 20 ++++++--------------
 Modules/Platform/Windows-Clang-OBJCXX.cmake | 20 ++++++--------------
 Modules/Platform/Windows-Clang.cmake        |  5 +++++
 8 files changed, 35 insertions(+), 80 deletions(-)

diff --git a/Modules/Compiler/Clang-C.cmake b/Modules/Compiler/Clang-C.cmake
index 24b7157e16..b7359b217a 100644
--- a/Modules/Compiler/Clang-C.cmake
+++ b/Modules/Compiler/Clang-C.cmake
@@ -5,11 +5,6 @@ if("x${CMAKE_C_COMPILER_FRONTEND_VARIANT}" STREQUAL "xMSVC")
   set(CMAKE_C_COMPILE_OPTIONS_EXPLICIT_LANGUAGE -TC)
   set(CMAKE_C_CLANG_TIDY_DRIVER_MODE "cl")
   set(CMAKE_C_INCLUDE_WHAT_YOU_USE_DRIVER_MODE "cl")
-  if((NOT DEFINED CMAKE_DEPENDS_USE_COMPILER OR CMAKE_DEPENDS_USE_COMPILER)
-      AND CMAKE_GENERATOR MATCHES "Makefiles|WMake"
-      AND CMAKE_DEPFILE_FLAGS_C)
-    set(CMAKE_C_DEPENDS_USE_COMPILER TRUE)
-  endif()
 elseif("x${CMAKE_C_COMPILER_FRONTEND_VARIANT}" STREQUAL "xGNU")
   set(CMAKE_C_COMPILE_OPTIONS_EXPLICIT_LANGUAGE -x c)
   if((NOT DEFINED CMAKE_DEPENDS_USE_COMPILER OR CMAKE_DEPENDS_USE_COMPILER)
diff --git a/Modules/Compiler/Clang-CXX.cmake b/Modules/Compiler/Clang-CXX.cmake
index 87a4cdd06a..a6412e9abf 100644
--- a/Modules/Compiler/Clang-CXX.cmake
+++ b/Modules/Compiler/Clang-CXX.cmake
@@ -18,11 +18,6 @@ endif()
 if("x${CMAKE_CXX_COMPILER_FRONTEND_VARIANT}" STREQUAL "xMSVC")
   set(CMAKE_CXX_CLANG_TIDY_DRIVER_MODE "cl")
   set(CMAKE_CXX_INCLUDE_WHAT_YOU_USE_DRIVER_MODE "cl")
-  if((NOT DEFINED CMAKE_DEPENDS_USE_COMPILER OR CMAKE_DEPENDS_USE_COMPILER)
-      AND CMAKE_GENERATOR MATCHES "Makefiles"
-      AND CMAKE_DEPFILE_FLAGS_CXX)
-    set(CMAKE_CXX_DEPENDS_USE_COMPILER TRUE)
-  endif()
 endif()
 
 if(CMAKE_CXX_COMPILER_VERSION VERSION_GREATER_EQUAL 16.0)
diff --git a/Modules/Platform/Windows-Clang-C.cmake b/Modules/Platform/Windows-Clang-C.cmake
index a90e4b7eb5..a1c52d95e0 100644
--- a/Modules/Platform/Windows-Clang-C.cmake
+++ b/Modules/Platform/Windows-Clang-C.cmake
@@ -1,18 +1,10 @@
 include(Platform/Windows-Clang)
 __windows_compiler_clang(C)
 
-if("x${CMAKE_C_COMPILER_FRONTEND_VARIANT}" STREQUAL "xMSVC")
-  if((NOT DEFINED CMAKE_DEPENDS_USE_COMPILER OR CMAKE_DEPENDS_USE_COMPILER)
-      AND CMAKE_GENERATOR MATCHES "Makefiles|WMake"
-      AND CMAKE_DEPFILE_FLAGS_C)
-    set(CMAKE_C_DEPENDS_USE_COMPILER TRUE)
-  endif()
-elseif("x${CMAKE_C_COMPILER_FRONTEND_VARIANT}" STREQUAL "xGNU")
-  if((NOT DEFINED CMAKE_DEPENDS_USE_COMPILER OR CMAKE_DEPENDS_USE_COMPILER)
-      AND CMAKE_GENERATOR MATCHES "Makefiles|WMake"
-      AND CMAKE_DEPFILE_FLAGS_C)
-    # dependencies are computed by the compiler itself
-    set(CMAKE_C_DEPFILE_FORMAT gcc)
-    set(CMAKE_C_DEPENDS_USE_COMPILER TRUE)
-  endif()
+if((NOT DEFINED CMAKE_DEPENDS_USE_COMPILER OR CMAKE_DEPENDS_USE_COMPILER)
+    AND CMAKE_GENERATOR MATCHES "Makefiles|WMake"
+    AND CMAKE_DEPFILE_FLAGS_C)
+  # dependencies are computed by the compiler itself
+  set(CMAKE_C_DEPFILE_FORMAT gcc)
+  set(CMAKE_C_DEPENDS_USE_COMPILER TRUE)
 endif()
diff --git a/Modules/Platform/Windows-Clang-CXX.cmake b/Modules/Platform/Windows-Clang-CXX.cmake
index af2a48f72c..66240883d6 100644
--- a/Modules/Platform/Windows-Clang-CXX.cmake
+++ b/Modules/Platform/Windows-Clang-CXX.cmake
@@ -2,18 +2,10 @@ include(Platform/Windows-Clang)
 set(_COMPILE_CXX_MSVC " -TP")
 __windows_compiler_clang(CXX)
 
-if("x${CMAKE_CXX_COMPILER_FRONTEND_VARIANT}" STREQUAL "xMSVC")
-  if((NOT DEFINED CMAKE_DEPENDS_USE_COMPILER OR CMAKE_DEPENDS_USE_COMPILER)
-      AND CMAKE_GENERATOR MATCHES "Makefiles|WMake"
-      AND CMAKE_DEPFILE_FLAGS_CXX)
-    set(CMAKE_CXX_DEPENDS_USE_COMPILER TRUE)
-  endif()
-elseif("x${CMAKE_CXX_COMPILER_FRONTEND_VARIANT}" STREQUAL "xGNU")
-  if((NOT DEFINED CMAKE_DEPENDS_USE_COMPILER OR CMAKE_DEPENDS_USE_COMPILER)
-      AND CMAKE_GENERATOR MATCHES "Makefiles|WMake"
-      AND CMAKE_DEPFILE_FLAGS_CXX)
-    # dependencies are computed by the compiler itself
-    set(CMAKE_CXX_DEPFILE_FORMAT gcc)
-    set(CMAKE_CXX_DEPENDS_USE_COMPILER TRUE)
-  endif()
+if((NOT DEFINED CMAKE_DEPENDS_USE_COMPILER OR CMAKE_DEPENDS_USE_COMPILER)
+    AND CMAKE_GENERATOR MATCHES "Makefiles|WMake"
+    AND CMAKE_DEPFILE_FLAGS_CXX)
+  # dependencies are computed by the compiler itself
+  set(CMAKE_CXX_DEPFILE_FORMAT gcc)
+  set(CMAKE_CXX_DEPENDS_USE_COMPILER TRUE)
 endif()
diff --git a/Modules/Platform/Windows-Clang-HIP.cmake b/Modules/Platform/Windows-Clang-HIP.cmake
index 75b38e23a4..bb80e59fa5 100644
--- a/Modules/Platform/Windows-Clang-HIP.cmake
+++ b/Modules/Platform/Windows-Clang-HIP.cmake
@@ -2,18 +2,10 @@ include(Platform/Windows-Clang)
 set(_COMPILE_HIP_MSVC " -x hip")
 __windows_compiler_clang(HIP)
 
-if("x${CMAKE_HIP_COMPILER_FRONTEND_VARIANT}" STREQUAL "xMSVC")
-  if((NOT DEFINED CMAKE_DEPENDS_USE_COMPILER OR CMAKE_DEPENDS_USE_COMPILER)
-      AND CMAKE_GENERATOR MATCHES "Makefiles|WMake"
-      AND CMAKE_DEPFILE_FLAGS_HIP)
-    set(CMAKE_HIP_DEPENDS_USE_COMPILER TRUE)
-  endif()
-elseif("x${CMAKE_HIP_COMPILER_FRONTEND_VARIANT}" STREQUAL "xGNU")
-  if((NOT DEFINED CMAKE_DEPENDS_USE_COMPILER OR CMAKE_DEPENDS_USE_COMPILER)
-      AND CMAKE_GENERATOR MATCHES "Makefiles|WMake"
-      AND CMAKE_DEPFILE_FLAGS_HIP)
-    # dependencies are computed by the compiler itself
-    set(CMAKE_HIP_DEPFILE_FORMAT gcc)
-    set(CMAKE_HIP_DEPENDS_USE_COMPILER TRUE)
-  endif()
+if((NOT DEFINED CMAKE_DEPENDS_USE_COMPILER OR CMAKE_DEPENDS_USE_COMPILER)
+    AND CMAKE_GENERATOR MATCHES "Makefiles|WMake"
+    AND CMAKE_DEPFILE_FLAGS_HIP)
+  # dependencies are computed by the compiler itself
+  set(CMAKE_HIP_DEPFILE_FORMAT gcc)
+  set(CMAKE_HIP_DEPENDS_USE_COMPILER TRUE)
 endif()
diff --git a/Modules/Platform/Windows-Clang-OBJC.cmake b/Modules/Platform/Windows-Clang-OBJC.cmake
index 7babb9807a..7e9a1642a0 100644
--- a/Modules/Platform/Windows-Clang-OBJC.cmake
+++ b/Modules/Platform/Windows-Clang-OBJC.cmake
@@ -1,18 +1,10 @@
 include(Platform/Windows-Clang)
 __windows_compiler_clang(OBJC)
 
-if("x${CMAKE_OBJC_COMPILER_FRONTEND_VARIANT}" STREQUAL "xMSVC")
-  if((NOT DEFINED CMAKE_DEPENDS_USE_COMPILER OR CMAKE_DEPENDS_USE_COMPILER)
-      AND CMAKE_GENERATOR MATCHES "Makefiles|WMake"
-      AND CMAKE_DEPFILE_FLAGS_OBJC)
-    set(CMAKE_OBJC_DEPENDS_USE_COMPILER TRUE)
-  endif()
-elseif("x${CMAKE_OBJC_COMPILER_FRONTEND_VARIANT}" STREQUAL "xGNU")
-  if((NOT DEFINED CMAKE_DEPENDS_USE_COMPILER OR CMAKE_DEPENDS_USE_COMPILER)
-      AND CMAKE_GENERATOR MATCHES "Makefiles|WMake"
-      AND CMAKE_DEPFILE_FLAGS_OBJC)
-    # dependencies are computed by the compiler itself
-    set(CMAKE_OBJC_DEPFILE_FORMAT gcc)
-    set(CMAKE_OBJC_DEPENDS_USE_COMPILER TRUE)
-  endif()
+if((NOT DEFINED CMAKE_DEPENDS_USE_COMPILER OR CMAKE_DEPENDS_USE_COMPILER)
+    AND CMAKE_GENERATOR MATCHES "Makefiles|WMake"
+    AND CMAKE_DEPFILE_FLAGS_OBJC)
+  # dependencies are computed by the compiler itself
+  set(CMAKE_OBJC_DEPFILE_FORMAT gcc)
+  set(CMAKE_OBJC_DEPENDS_USE_COMPILER TRUE)
 endif()
diff --git a/Modules/Platform/Windows-Clang-OBJCXX.cmake b/Modules/Platform/Windows-Clang-OBJCXX.cmake
index 3bc16731b1..55b9070cc4 100644
--- a/Modules/Platform/Windows-Clang-OBJCXX.cmake
+++ b/Modules/Platform/Windows-Clang-OBJCXX.cmake
@@ -1,18 +1,10 @@
 include(Platform/Windows-Clang)
 __windows_compiler_clang(OBJCXX)
 
-if("x${CMAKE_OBJCXX_COMPILER_FRONTEND_VARIANT}" STREQUAL "xMSVC")
-  if((NOT DEFINED CMAKE_DEPENDS_USE_COMPILER OR CMAKE_DEPENDS_USE_COMPILER)
-      AND CMAKE_GENERATOR MATCHES "Makefiles|WMake"
-      AND CMAKE_DEPFILE_FLAGS_OBJCXX)
-    set(CMAKE_OBJCXX_DEPENDS_USE_COMPILER TRUE)
-  endif()
-elseif("x${CMAKE_OBJCXX_COMPILER_FRONTEND_VARIANT}" STREQUAL "xGNU")
-  if((NOT DEFINED CMAKE_DEPENDS_USE_COMPILER OR CMAKE_DEPENDS_USE_COMPILER)
-      AND CMAKE_GENERATOR MATCHES "Makefiles|WMake"
-      AND CMAKE_DEPFILE_FLAGS_OBJCXX)
-    # dependencies are computed by the compiler itself
-    set(CMAKE_OBJCXX_DEPFILE_FORMAT gcc)
-    set(CMAKE_OBJCXX_DEPENDS_USE_COMPILER TRUE)
-  endif()
+if((NOT DEFINED CMAKE_DEPENDS_USE_COMPILER OR CMAKE_DEPENDS_USE_COMPILER)
+    AND CMAKE_GENERATOR MATCHES "Makefiles|WMake"
+    AND CMAKE_DEPFILE_FLAGS_OBJCXX)
+  # dependencies are computed by the compiler itself
+  set(CMAKE_OBJCXX_DEPFILE_FORMAT gcc)
+  set(CMAKE_OBJCXX_DEPENDS_USE_COMPILER TRUE)
 endif()
diff --git a/Modules/Platform/Windows-Clang.cmake b/Modules/Platform/Windows-Clang.cmake
index 82e9d8205e..0c002dd847 100644
--- a/Modules/Platform/Windows-Clang.cmake
+++ b/Modules/Platform/Windows-Clang.cmake
@@ -233,6 +233,11 @@ if("x${CMAKE_C_SIMULATE_ID}" STREQUAL "xMSVC"
     macro(__windows_compiler_clang_base lang)
       set(_COMPILE_${lang} "${_COMPILE_${lang}_MSVC}")
       __windows_compiler_msvc(${lang})
+
+      # Prefer clang-cl's gcc-style depfile over cl-style /showIncludes
+      set(CMAKE_DEPFILE_FLAGS_${lang} "-clang:-MD -clang:-MT<DEP_TARGET> -clang:-MF<DEP_FILE>")
+      unset(CMAKE_${lang}_DEPFILE_FORMAT)
+
       unset(CMAKE_${lang}_COMPILE_OPTIONS_MSVC_DEBUG_INFORMATION_FORMAT_EditAndContinue) # -ZI not supported by Clang
       set(CMAKE_${lang}_COMPILE_OPTIONS_WARNING_AS_ERROR "-WX")
       set(CMAKE_INCLUDE_SYSTEM_FLAG_${lang} "-imsvc")