Makefiles Generators: use compiler for dependencies generation

Each source compilation generates a dependencies file. These dependencies
files are consolidated in one file per target. This consolidation is done
as part of command 'cmake -E cmake_depends` launched before evaluation of
makefile dependency graph.

The consolidation uses the same approach as `CMake` dependencies management.

Fixes: #21321

Help/manual/cmake-variables.7.rst

@@ -387,6 +387,7 @@ Variables that Control the Build
    /variable/CMAKE_DEFAULT_BUILD_TYPE
    /variable/CMAKE_DEFAULT_CONFIGS
    /variable/CMAKE_DISABLE_PRECOMPILE_HEADERS
+   /variable/CMAKE_DEPENDS_USE_COMPILER
    /variable/CMAKE_ENABLE_EXPORTS
    /variable/CMAKE_EXE_LINKER_FLAGS
    /variable/CMAKE_EXE_LINKER_FLAGS_CONFIG

Help/release/dev/makefiles-dependencies-use-compiler.rst

+makefiles-dependencies-use-compiler
+-----------------------------------
+
+* The :ref:`Makefile Generators` gained the capability, for a selection of
+  compilers, to use the compiler itself to generate implicit dependencies.

Help/variable/CMAKE_DEPENDS_USE_COMPILER.rst

+CMAKE_DEPENDS_USE_COMPILER
+--------------------------
+
+.. versionadded:: 3.20
+
+For the :ref:`Makefile Generators`, source dependencies are now, for a
+selection of compilers, generated by the compiler itself. By defining this
+variable with value ``FALSE``, you can restore the legacy behavior (i.e. using
+``CMake`` for dependencies discovery).

Modules/CMakeDetermineCompilerId.cmake

@@ -152,7 +152,10 @@ function(CMAKE_DETERMINE_COMPILER_ID lang flagvar src)
     set(CMAKE_EXECUTABLE_FORMAT "Unknown" CACHE INTERNAL "Executable file format")
   endif()
 
-  if(CMAKE_GENERATOR MATCHES "^Ninja" AND MSVC_${lang}_ARCHITECTURE_ID)
+  if((CMAKE_GENERATOR MATCHES "^Ninja"
+        OR ((NOT DEFINED CMAKE_DEPENDS_USE_COMPILER OR CMAKE_DEPENDS_USE_COMPILER)
+          AND CMAKE_GENERATOR MATCHES "Makefiles|WMake"))
+      AND MSVC_${lang}_ARCHITECTURE_ID)
     foreach(userflags "${CMAKE_${lang}_COMPILER_ID_FLAGS_LIST}" "")
       CMAKE_DETERMINE_MSVC_SHOWINCLUDES_PREFIX(${lang} "${userflags}")
     endforeach()

Modules/Compiler/AppleClang-C.cmake

 include(Compiler/Clang)
 __compiler_clang(C)
 
+
+if(NOT "x${CMAKE_C_SIMULATE_ID}" STREQUAL "xMSVC")
+  if((NOT DEFINED CMAKE_DEPENDS_USE_COMPILER OR CMAKE_DEPENDS_USE_COMPILER)
+      AND CMAKE_GENERATOR MATCHES "Makefiles"
+      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()
+endif()
+
+
 if(NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 4.0)
   set(CMAKE_C90_STANDARD_COMPILE_OPTION "-std=c90")
   set(CMAKE_C90_EXTENSION_COMPILE_OPTION "-std=gnu90")

Modules/Compiler/AppleClang-CXX.cmake

@@ -2,6 +2,14 @@ include(Compiler/Clang)
 __compiler_clang(CXX)
 
 if(NOT "x${CMAKE_CXX_SIMULATE_ID}" STREQUAL "xMSVC")
+  if((NOT DEFINED CMAKE_DEPENDS_USE_COMPILER OR CMAKE_DEPENDS_USE_COMPILER)
+      AND CMAKE_GENERATOR MATCHES "Makefiles"
+      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()
+
   set(CMAKE_CXX_COMPILE_OPTIONS_VISIBILITY_INLINES_HIDDEN "-fvisibility-inlines-hidden")
 endif()
 

Modules/Compiler/AppleClang-OBJC.cmake

 include(Compiler/Clang-OBJC)
 
+if((NOT DEFINED CMAKE_DEPENDS_USE_COMPILER OR CMAKE_DEPENDS_USE_COMPILER)
+    AND CMAKE_GENERATOR MATCHES "Makefiles"
+    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 CMAKE_OBJC_COMPILER_VERSION VERSION_LESS 4.0)
   set(CMAKE_OBJC90_STANDARD_COMPILE_OPTION "-std=c90")
   set(CMAKE_OBJC90_EXTENSION_COMPILE_OPTION "-std=gnu90")

Modules/Compiler/AppleClang-OBJCXX.cmake

 include(Compiler/Clang-OBJCXX)
 
+
+if((NOT DEFINED CMAKE_DEPENDS_USE_COMPILER OR CMAKE_DEPENDS_USE_COMPILER)
+    AND CMAKE_GENERATOR MATCHES "Makefiles"
+    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()
+
+
 set(CMAKE_OBJCXX_COMPILE_OPTIONS_VISIBILITY_INLINES_HIDDEN "-fvisibility-inlines-hidden")
 
 if(NOT CMAKE_OBJCXX_COMPILER_VERSION VERSION_LESS 4.0)

Modules/Compiler/Clang-C.cmake

@@ -8,6 +8,19 @@ endif()
 
 if("x${CMAKE_C_COMPILER_FRONTEND_VARIANT}" STREQUAL "xMSVC")
   set(CMAKE_C_CLANG_TIDY_DRIVER_MODE "cl")
+  if((NOT DEFINED CMAKE_DEPENDS_USE_COMPILER OR CMAKE_DEPENDS_USE_COMPILER)
+      AND CMAKE_GENERATOR MATCHES "Makefiles|WMake"
+      AND CMAKE_DEPFILE_FLAGS_C)
+    set(CMAKE_C_DEPENDS_USE_COMPILER TRUE)
+  endif()
+elseif("x${CMAKE_C_COMPILER_FRONTEND_VARIANT}" STREQUAL "xGNU")
+  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()
 endif()
 
 if(NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 3.4)

Modules/Compiler/Clang-CUDA.cmake

@@ -3,6 +3,12 @@ __compiler_clang(CUDA)
 
 # Set explicitly, because __compiler_clang() doesn't set this if we're simulating MSVC.
 set(CMAKE_DEPFILE_FLAGS_CUDA "-MD -MT <DEP_TARGET> -MF <DEP_FILE>")
+if((NOT DEFINED CMAKE_DEPENDS_USE_COMPILER OR CMAKE_DEPENDS_USE_COMPILER)
+    AND CMAKE_GENERATOR MATCHES "Makefiles|WMake")
+  # dependencies are computed by the compiler itself
+  set(CMAKE_CUDA_DEPFILE_FORMAT gcc)
+  set(CMAKE_CUDA_DEPENDS_USE_COMPILER TRUE)
+endif()
 
 # C++03 isn't supported for CXX, but is for CUDA, so we need to set these manually.
 # Do this before __compiler_clang_cxx_standards() since that adds the feature.

Modules/Compiler/Clang-CXX.cmake

@@ -3,6 +3,14 @@ __compiler_clang(CXX)
 __compiler_clang_cxx_standards(CXX)
 
 if("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()
+
   set(CMAKE_CXX_COMPILE_OPTIONS_VISIBILITY_INLINES_HIDDEN "-fvisibility-inlines-hidden")
 endif()
 
@@ -13,4 +21,9 @@ endif()
 
 if("x${CMAKE_CXX_COMPILER_FRONTEND_VARIANT}" STREQUAL "xMSVC")
   set(CMAKE_CXX_CLANG_TIDY_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()

Modules/Compiler/Clang-OBJC.cmake

 include(Compiler/Clang)
 __compiler_clang(OBJC)
 
+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 CMAKE_OBJC_COMPILER_VERSION VERSION_LESS 3.4)
   set(CMAKE_OBJC90_STANDARD_COMPILE_OPTION "-std=c90")
   set(CMAKE_OBJC90_EXTENSION_COMPILE_OPTION "-std=gnu90")

Modules/Compiler/Clang-OBJCXX.cmake

 include(Compiler/Clang)
 __compiler_clang(OBJCXX)
 __compiler_clang_cxx_standards(OBJCXX)
+
+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()

Modules/Compiler/GNU-C.cmake

 include(Compiler/GNU)
 __compiler_gnu(C)
 
+
+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 CMAKE_C_COMPILER_VERSION VERSION_LESS 4.5)
   set(CMAKE_C90_STANDARD_COMPILE_OPTION "-std=c90")
   set(CMAKE_C90_EXTENSION_COMPILE_OPTION "-std=gnu90")

Modules/Compiler/GNU-CXX.cmake

 include(Compiler/GNU)
 __compiler_gnu(CXX)
 
+
+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 (WIN32)
   if(NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 4.6)
     set(CMAKE_CXX_COMPILE_OPTIONS_VISIBILITY_INLINES_HIDDEN "-fno-keep-inline-dllexport")

Modules/Compiler/GNU-OBJC.cmake

 include(Compiler/GNU)
 __compiler_gnu(OBJC)
+
+
+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()

Modules/Compiler/GNU-OBJCXX.cmake

 include(Compiler/GNU)
 __compiler_gnu(OBJCXX)
 
+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 CMAKE_OBJCXX_COMPILER_VERSION VERSION_LESS 4.2)
   set(CMAKE_OBJCXX_COMPILE_OPTIONS_VISIBILITY_INLINES_HIDDEN "-fvisibility-inlines-hidden")
 endif()

Modules/Compiler/Intel-C.cmake

@@ -6,6 +6,12 @@ string(APPEND CMAKE_C_FLAGS_RELEASE_INIT " -DNDEBUG")
 string(APPEND CMAKE_C_FLAGS_RELWITHDEBINFO_INIT " -DNDEBUG")
 
 set(CMAKE_DEPFILE_FLAGS_C "-MD -MT <DEP_TARGET> -MF <DEP_FILE>")
+if((NOT DEFINED CMAKE_DEPENDS_USE_COMPILER OR CMAKE_DEPENDS_USE_COMPILER)
+    AND CMAKE_GENERATOR MATCHES "Makefiles|WMake")
+  # dependencies are computed by the compiler itself
+  set(CMAKE_C_DEPFILE_FORMAT gcc)
+  set(CMAKE_C_DEPENDS_USE_COMPILER TRUE)
+endif()
 
 if("x${CMAKE_C_SIMULATE_ID}" STREQUAL "xMSVC")
 

Modules/Compiler/Intel-CXX.cmake

@@ -6,6 +6,12 @@ string(APPEND CMAKE_CXX_FLAGS_RELEASE_INIT " -DNDEBUG")
 string(APPEND CMAKE_CXX_FLAGS_RELWITHDEBINFO_INIT " -DNDEBUG")
 
 set(CMAKE_DEPFILE_FLAGS_CXX "-MD -MT <DEP_TARGET> -MF <DEP_FILE>")
+if((NOT DEFINED CMAKE_DEPENDS_USE_COMPILER OR CMAKE_DEPENDS_USE_COMPILER)
+    AND CMAKE_GENERATOR MATCHES "Makefiles|WMake")
+  # dependencies are computed by the compiler itself
+  set(CMAKE_CXX_DEPFILE_FORMAT gcc)
+  set(CMAKE_CXX_DEPENDS_USE_COMPILER TRUE)
+endif()
 
 if("x${CMAKE_CXX_SIMULATE_ID}" STREQUAL "xMSVC")
 

Modules/Compiler/Intel-ISPC.cmake

@@ -4,6 +4,12 @@ include(Compiler/CMakeCommonCompilerMacros)
 #set(CMAKE_ISPC_VERBOSE_FLAG )
 
 set(CMAKE_DEPFILE_FLAGS_ISPC "-M -MT <DEP_TARGET> -MF <DEP_FILE>")
+if((NOT DEFINED CMAKE_DEPENDS_USE_COMPILER OR CMAKE_DEPENDS_USE_COMPILER)
+    AND CMAKE_GENERATOR MATCHES "Makefiles|WMake")
+  # dependencies are computed by the compiler itself
+  set(CMAKE_ISPC_DEPFILE_FORMAT gcc)
+  set(CMAKE_ISPC_DEPENDS_USE_COMPILER TRUE)
+endif()
 
 string(APPEND CMAKE_ISPC_FLAGS_INIT " ")
 string(APPEND CMAKE_ISPC_FLAGS_DEBUG_INIT "-O0 -g")