Add option to enable ccache to build

- Add ENABLE_CCACHE flag to cmake
- Install ccache in dev container
- Always enable caching in CMakePresets.json

Author: dariusarnold

CMakeLists.txt

@@ -31,6 +31,10 @@ if(BUILD_RESOURCES)
   set(BUILD_RESOURCES true)
 endif()
 
+if(ENABLE_CCACHE)
+  include(cmake/ccache.cmake)
+endif()
+
 set(TARGET_DEVICE "PINETIME" CACHE STRING "Target device")
 set_property(CACHE TARGET_DEVICE PROPERTY STRINGS PINETIME MOY_TFK5 MOY_TIN5 MOY_TON5 MOY_UNK)
 

CMakePresets.json

@@ -31,6 +31,10 @@
         "TARGET_DEVICE": {
           "type": "STRING",
           "value": "PINETIME"
+        },
+        "ENABLE_CCACHE": {
+          "type": "BOOL",
+          "value": true
         }
       }
     },

cmake/ccache.cmake

@@ -0,0 +1,14 @@
+find_program(CCACHE_EXECUTABLE ccache)
+
+if (CCACHE_EXECUTABLE)
+    message(STATUS "Activating ccache compiler cache.")
+    set(ccacheEnv
+        CCACHE_SLOPPINESS=pch_defines
+    )
+    foreach (lang IN ITEMS C CXX)
+        set(CMAKE_${lang}_COMPILER_LAUNCHER
+            ${CMAKE_COMMAND} -E env ${ccacheEnv} ${CCACHE_EXECUTABLE}
+        )
+    endforeach ()
+    message(WARNING "Ccache could not be activated because ccache executable was not found.")
+endif ()

docker/Dockerfile

@@ -12,6 +12,7 @@ RUN apt-get update -qq \
 # x86_64 / generic packages
       bash \
       build-essential \
+      ccache \
       cmake \
       git \
       make \