build: enable_ccache() refactored

CMakeLists.txt

@@ -33,7 +33,7 @@ ensure_entry_point()
 
 # use ccache if available
 include(ccache)
-enable_ccache_if_possible()
+enable_ccache()
 
 # set restrictive compilation warnings
 include(warnings)

cmake/ccache.cmake

@@ -22,24 +22,54 @@
 
 cmake_minimum_required(VERSION 3.4)
 
-include(modern_project_structure)
+macro(_enable_ccache_failed)
-
+    if(NOT _enable_ccache_QUIET)
-macro(_enable_ccache)
+        message(STATUS "Enabling ccache - failed")
-    set(_options ACCOUNT_FOR_COMPILE_TIME_HEADER_CHANGES ACCOUNT_FOR_PCH ACCOUNT_FOR_MODULES)
+    endif()
-    set(_one_value_args MODE BASE_DIR)
+    return()
-    set(_multi_value_args PREFIXES)
+endmacro()
-    cmake_parse_arguments(PARSE_ARGV 0 _enable_ccache "${_options}" "${_one_value_args}" "${_multi_value_args}")
 
+#
+# enable_ccache([PROGRAM]                                                    # ccache by default
+#               [QUIET] [REQUIRED]
+#               [MODE DIRECT_PREPROCESSOR|DIRECT_DEPEND|PREPROCESSOR|DEPEND] # DIRECT_PREPROCESSOR by default
+#               [BASE_DIR dir]                                               # ${CMAKE_SOURCE_DIR} by default
+#               [ACCOUNT_FOR_COMPILE_TIME_HEADER_CHANGES]
+#               [ACCOUNT_FOR_PCH]
+#               [ACCOUNT_FOR_MODULES]
+#               [PREFIXES prefixes...]
+#               )
+# 
+# BASE_DIR
+# Set this option to ${CMAKE_BINARY_DIR} if you use FetchContent a lot for many projects with the same build options.
+# Otherwise, if most of the sources come from the project itself then the default ${CMAKE_SOURCE_DIR} may be
+# a better choice.
+# 
+# ACCOUNT_FOR_COMPILE_TIME_HEADER_CHANGES
+# Use it if some header files are being generated by the compilation process.
+# 
+# ACCOUNT_FOR_PCH
+# Use it if precompiled headers are enabled in your project. Automatically includes uses
+# ACCOUNT_FOR_COMPILE_TIME_HEADER_CHANGES as well.
+# See here for details: https://ccache.dev/manual/4.2.1.html#_precompiled_headers
+# 
+# ACCOUNT_FOR_MODULES
+# Use it for projects with C++20 modules. Requires DIRECT_DEPEND mode.
+#
+# PREFIXES
+# A list of other tools that should be used together with ccache as a compiler launcher
+# (i.e. distcc, icecc, sccache-dist, ...).
+# 
+function(enable_ccache)
     if(NOT CMAKE_CURRENT_SOURCE_DIR STREQUAL CMAKE_SOURCE_DIR)
         message(FATAL_ERROR "'enable_ccache' function should be called from the top-level CMakeLists.txt file!")
         # otherwise, it will not work for XCode
-        return()
     endif()
 
-    set(_ccacheEnv
+    set(_options QUIET REQUIRED ACCOUNT_FOR_COMPILE_TIME_HEADER_CHANGES ACCOUNT_FOR_PCH ACCOUNT_FOR_MODULES)
-        CCACHE_CPP2=1 # avoids spurious warnings with some compilers for ccache older than 3.3
+    set(_one_value_args PROGRAM MODE BASE_DIR)
-        # CCACHE_ABSSTDERR=1 # reverts absolute paths after applying CCACHE_BASEDIR
+    set(_multi_value_args PREFIXES)
-    )
+    cmake_parse_arguments(PARSE_ARGV 0 _enable_ccache "${_options}" "${_one_value_args}" "${_multi_value_args}")
 
     # validate and process arguments
     if(_enable_ccache_UNPARSED_ARGUMENTS)
@@ -57,6 +87,56 @@ macro(_enable_ccache)
         endif()
     endif()
         
+    if(NOT _enable_ccache_QUIET)
+        message(STATUS "Enabling ccache")
+    endif()
+
+    if(${_enable_ccache_REQUIRED})
+        set(_error_log_level FATAL_ERROR)
+    elseif(NOT _enable_ccache_QUIET)
+        set(_error_log_level STATUS)
+    endif()
+
+    if(NOT CMAKE_GENERATOR MATCHES "Ninja|Makefiles|Xcode")
+        if(DEFINED _error_log_level)
+            message(${_error_log_level} "ccache support not enabled: unsupported generator '${CMAKE_GENERATOR}'")
+        endif()
+        _enable_ccache_failed()
+    endif()
+
+    if(NOT DEFINED _enable_ccache_PROGRAM)
+        set(_enable_ccache_PROGRAM ccache)
+    endif()
+
+    find_program(CCACHE_PATH ${_enable_ccache_PROGRAM})
+    if(CCACHE_PATH)
+        if(NOT _enable_ccache_QUIET)
+            message(STATUS "  Executable: ${CCACHE_PATH}")
+        endif()
+
+        # get version number
+        execute_process(COMMAND "${CCACHE_PATH}" --version OUTPUT_VARIABLE _output)
+        string(REPLACE "\n" ";" _output "${_output}")
+        foreach(_line ${_output})
+            string(REGEX REPLACE "ccache version ([\\.0-9]+)$" "\\1" _ccache_version "${_line}")
+            if(_ccache_version)
+                if(NOT _enable_ccache_QUIET)
+                    message(STATUS "  Version: ${_ccache_version}")
+                endif()
+                break()
+            endif()
+        endforeach()
+    else()
+        if(DEFINED _error_log_level)
+            message(${_error_log_level} "  '${_enable_ccache_PROGRAM}' executable was not found")
+        endif()
+        _enable_ccache_failed()
+    endif()
+
+    if("${_ccache_version}" VERSION_LESS 3.3.0)
+        list(APPEND _ccacheEnv CCACHE_CPP2=1)  # avoids spurious warnings with some compilers for ccache older than 3.3
+    endif()
+
     if(_enable_ccache_MODE STREQUAL DIRECT_DEPEND)
         list(APPEND _ccacheEnv CCACHE_DIRECT=1 CCACHE_DEPEND=1)
     elseif(_enable_ccache_MODE STREQUAL PREPROCESSOR)
@@ -69,6 +149,7 @@ macro(_enable_ccache)
     endif()
 
     if(_enable_ccache_BASE_DIR)
+        # CCACHE_ABSSTDERR=1 # reverts absolute paths after applying CCACHE_BASEDIR
         if(NOT EXISTS ${_enable_ccache_BASE_DIR})
             message(FATAL_ERROR "Base directory '${_enable_ccache_BASE_DIR}' does not exist")
         endif()
@@ -103,13 +184,15 @@ macro(_enable_ccache)
         list(APPEND _ccacheEnv "CCACHE_SLOPPINESS=${_sloppiness_txt}")
     endif()
 
-    message(STATUS "Enabling ccache with '${_ccacheEnv}'")
+    if(NOT _enable_ccache_QUIET)
+        message(STATUS "  Environment: ${_ccacheEnv}")
+    endif()
 
     if(CMAKE_GENERATOR MATCHES "Ninja|Makefiles")
         foreach(_lang IN ITEMS C CXX OBJC OBJCXX CUDA)
             set(CMAKE_${_lang}_COMPILER_LAUNCHER
                 ${CMAKE_COMMAND} -E env
-                ${_ccacheEnv} ${_ccache_path}
+                ${_ccacheEnv} ${CCACHE_PATH}
                 PARENT_SCOPE
             )
         endforeach()
@@ -132,62 +215,9 @@ macro(_enable_ccache)
         set(CMAKE_XCODE_ATTRIBUTE_CXX ${launchCXX} PARENT_SCOPE)
         set(CMAKE_XCODE_ATTRIBUTE_LD ${launchC} PARENT_SCOPE)
         set(CMAKE_XCODE_ATTRIBUTE_LDPLUSPLUS ${launchCXX} PARENT_SCOPE)
-    else()
-        message(WARNING "'${CMAKE_GENERATOR}' generator is not supported by ccache!")
-        return()
-    endif()
-endmacro()
-
-
-#
-# enable_ccache([MODE DIRECT_PREPROCESSOR|DIRECT_DEPEND|PREPROCESSOR|DEPEND] # DIRECT_PREPROCESSOR by default
-#               [BASE_DIR dir]                                               # ${CMAKE_SOURCE_DIR} by default
-#               [ACCOUNT_FOR_COMPILE_TIME_HEADER_CHANGES]
-#               [ACCOUNT_FOR_PCH]
-#               [ACCOUNT_FOR_MODULES]
-#               [PREFIXES prefixes...])
-# 
-# BASE_DIR
-# Set this option to ${CMAKE_BINARY_DIR} if you use FetchContent a lot for many projects with the same build options.
-# Otherwise, if most of the sources come from the project itself then the default ${CMAKE_SOURCE_DIR} may be
-# a better choice.
-# 
-# ACCOUNT_FOR_COMPILE_TIME_HEADER_CHANGES
-# Use it if some header files are being generated by the compilation process.
-# 
-# ACCOUNT_FOR_PCH
-# Use it if precompiled headers are enabled in your project. Automatically includes uses
-# ACCOUNT_FOR_COMPILE_TIME_HEADER_CHANGES as well.
-# See here for details: https://ccache.dev/manual/4.2.1.html#_precompiled_headers
-# 
-# ACCOUNT_FOR_MODULES
-# Use it for projects with C++20 modules. Requires DIRECT_DEPEND mode.
-#
-# PREFIXES
-# A list of other tools that should be used together with ccache as a compiler launcher
-# (i.e. distcc, icecc, sccache-dist, ...).
-# 
-function(enable_ccache)
-    find_program(_ccache_path NAMES "ccache")
-    if(NOT _ccache_path)
-        message(FATAL_ERROR "'ccache' executable not found!")
-        return()
     endif()
 
-    _enable_ccache()
+    if(NOT _enable_ccache_QUIET)
-endfunction()
+        message(STATUS "Enabling ccache - done")
-
+    endif()
-function(enable_ccache_if_possible)
-    find_program(_ccache_path NAMES "ccache")
-    if(NOT _ccache_path)
-        message(STATUS "ccache support not enabled: the executable was not found")
-        return()
-    endif()
-
-    if(NOT CMAKE_GENERATOR MATCHES "Ninja|Makefiles|Xcode")
-        message(STATUS "ccache support not enabled: unsupported generator '${CMAKE_GENERATOR}'")
-        return()
-    endif()
-
-    _enable_ccache()
 endfunction()