Enable automatic compiler caching

CMakeLists.txt

@@ -43,6 +43,9 @@ set(CMAKE_INSTALL_RPATH ${base} ${base}/${relDir})
 
 include(BuildType)
 include(FindFFTW)
+include(CompilerCache)
+
+use_compiler_cache()
 
 add_compile_definitions(
     MRTRIX_BUILD_TYPE="${CMAKE_BUILD_TYPE}"

CMakePresets.json

@@ -6,10 +6,7 @@
             "displayName" : "Base configuration",
             "hidden" : true,
             "generator" : "Ninja",
-            "binaryDir": "${sourceParentDir}/mrtrix3-build-${presetName}",
-            "cacheVariables" : {
-                "CMAKE_CXX_COMPILER_LAUNCHER" : "ccache"
-            }
+            "binaryDir": "${sourceParentDir}/mrtrix3-build-${presetName}"
         },
         {
             "name": "debug",
@@ -33,7 +30,6 @@
             "inherits" : "base",
             "cacheVariables" : {
                 "CMAKE_BUILD_TYPE" : "Release",
-                "CMAKE_CXX_COMPILER_LAUNCHER" : "sccache",
                 "MRTRIX_STL_DEBUGGING" : "ON",
                 "MRTRIX_WARNINGS_AS_ERRORS" : "ON"
             }

cmake-instructions.md

@@ -27,13 +27,16 @@ For example, on Ubuntu you can add the following line to your `~/.bashrc`:
         $ cmake -B build mrtrix3
 
     If all the required dependencies are installed, `CMake` should correctly configure the project.
-    It's highly recommended that you use `Ninja` and `ccache` (or `sccache`) to configure the project,
-    to do this run `cmake -G Ninja -D CMAKE_CXX_COMPILER_LAUNCHER=ccache -B build mrtrix3` instead of
+    It's **highly** recommended that you use `Ninja` and `ccache` (or `sccache`) to configure the project,
+    to do this run `cmake -G Ninja -B build mrtrix3` instead of
     second step above. This will provide you faster compilations speeds. You can install `Ninja` and 
     `ccache` using your system's package manager (e.g. `brew install ninja ccache` or `apt install ninja ccache`).
-
+    The project will automatically detect if `ccache` (or `sccache`) is installed on your system. You can also specify your own custom compiler caching tool by setting the `CACHE_OPTION` variable
+    (by specifying `-DCACHE_OPTION=custom_cache_tool`).
+
     If you wish, we provide some default CMake presets that automatically configure the project using predefined
-    settings. You can view the list of available presets in [CMakePresets.json](https://github.com/MRtrix3/mrtrix3/blob/cmake_experimental_shared/CMakePresets.json). To configure the project using a given preset run
+    settings. You can view the list of available presets in [CMakePresets.json](https://github.com/MRtrix3/mrtrix3/blob/cmake_experimental_shared/CMakePresets.json)
+    or run `cmake --list-presets` in the source directory. To configure the project using a given preset run
 
         $ cmake --preset name_of_configure_preset
 

cmake/CompilerCache.cmake

@@ -0,0 +1,33 @@
+# Automatically enable compiler caching if available
+function(use_compiler_cache)
+  set(CACHE_OPTION
+      "ccache"
+      CACHE STRING "Compiler cache to be used")
+  set(CACHE_OPTION_VALUES "ccache" "sccache")
+  set_property(CACHE CACHE_OPTION PROPERTY STRINGS ${CACHE_OPTION_VALUES})
+  list(
+    FIND
+    CACHE_OPTION_VALUES
+    ${CACHE_OPTION}
+    CACHE_OPTION_INDEX)
+
+  if(${CACHE_OPTION_INDEX} EQUAL -1)
+    message(
+      STATUS
+        "Using custom compiler cache system: '${CACHE_OPTION}', explicitly supported entries are ${CACHE_OPTION_VALUES}"
+    )
+  endif()
+
+  find_program(CACHE_BINARY NAMES ${CACHE_OPTION_VALUES})
+  if(CACHE_BINARY)
+    message(STATUS "${CACHE_BINARY} found and enabled")
+    set(CMAKE_CXX_COMPILER_LAUNCHER
+        ${CACHE_BINARY}
+        CACHE FILEPATH "CXX compiler cache used")
+    set(CMAKE_C_COMPILER_LAUNCHER
+        ${CACHE_BINARY}
+        CACHE FILEPATH "C compiler cache used")
+  else()
+    message(WARNING "${CACHE_OPTION} is enabled but was not found. Not using it")
+  endif()
+endfunction()