feat: Remove automatic enabling of ccache for ccache build

When enabling ccache using the standard recommended method (via PATH or
via masquerading symlinks), UseCcache.cmake will introduce double
invocations of ccache. I find this a bit annoying and I also think that
it should be up to the user to enable or not enable ccache and which
settings to use.

diff --git a/CMakeLists.txt b/CMakeLists.txt
index fcc2134bd13a6153eed5dd5090afdb01b3ea76df..1616b294628f1d3b7339c8ed1403b85915ac3e71 100644 (file)
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -70,7 +70,6 @@ if(ENABLE_IPO AND NOT MINGW)
   set(CMAKE_INTERPROCEDURAL_OPTIMIZATION ON)
 endif()
 
-include(UseCcache)
 include(UseFastestLinker)
 include(StandardSettings)
 include(StandardWarnings)

diff --git a/cmake/UseCcache.cmake b/cmake/UseCcache.cmake
deleted file mode 100644 (file)
index 3137d85..0000000
--- a/cmake/UseCcache.cmake
+++ /dev/null
@@ -1,74 +0,0 @@
-# Note: Compiling ccache via ccache is fine because the ccache version installed
-# in the system is used.
-
-# Calls `message(VERBOSE msg)` if and only if VERBOSE is available (since CMake
-# 3.15). Call CMake with --log-level=VERBOSE to view verbose messages.
-function(message_verbose msg)
-  if(NOT ${CMAKE_VERSION} VERSION_LESS "3.15")
-    message(VERBOSE ${msg})
-  endif()
-endfunction()
-
-function(use_ccache)
-  if(NOT CMAKE_CURRENT_SOURCE_DIR STREQUAL CMAKE_SOURCE_DIR)
-    message(WARNING "use_ccache() disabled, as it is not called from the project top level")
-    return()
-  endif()
-
-  find_program(CCACHE_PROGRAM ccache)
-  if(NOT CCACHE_PROGRAM)
-    message_verbose("Ccache program not found, not enabling ccache for faster recompilation")
-    return()
-  endif()
-
-  message_verbose("Ccache enabled for faster recompilation")
-
-  # Note: This will override any config and environment settings.
-  set(ccache_env
-    # Another option would be CMAKE_BINARY_DIR, but currently only one base
-    # directory is supported.
-    CCACHE_BASEDIR=${CMAKE_SOURCE_DIR}
-
-    # In case of very old ccache versions (pre 3.3).
-    CCACHE_CPP2=true
-  )
-
-  if(CMAKE_GENERATOR MATCHES "Ninja|Makefiles")
-    find_program(ENV_PROGRAM env)
-    if(ENV_PROGRAM)
-      set(env_program ${ENV_PROGRAM}) # faster than "cmake -E env"
-    else()
-      set(env_program ${CMAKE_COMMAND} -E env)
-    endif()
-    foreach(lang IN ITEMS C CXX OBJC OBJCXX CUDA)
-      set(CMAKE_${lang}_COMPILER_LAUNCHER
-        ${env_program} ${ccache_env} ${CCACHE_PROGRAM}
-        PARENT_SCOPE)
-    endforeach()
-  elseif(CMAKE_GENERATOR STREQUAL Xcode)
-    foreach(lang IN ITEMS C CXX)
-      set(launcher ${CMAKE_BINARY_DIR}/launch-${lang})
-      file(WRITE ${launcher} "#!/bin/bash\n\n")
-      foreach(key_val IN LISTS ccache_env)
-        file(APPEND ${launcher} "export ${key_val}\n")
-      endforeach()
-      file(APPEND ${launcher}
-        "exec \"${CCACHE_PROGRAM}\" \"${CMAKE_${lang}_COMPILER}\" \"$@\"\n")
-      execute_process(COMMAND chmod a+rx ${launcher})
-    endforeach()
-    set(CMAKE_XCODE_ATTRIBUTE_CC ${CMAKE_BINARY_DIR}/launch-C PARENT_SCOPE)
-    set(CMAKE_XCODE_ATTRIBUTE_CXX ${CMAKE_BINARY_DIR}/launch-CXX PARENT_SCOPE)
-    set(CMAKE_XCODE_ATTRIBUTE_LD ${CMAKE_BINARY_DIR}/launch-C PARENT_SCOPE)
-    set(CMAKE_XCODE_ATTRIBUTE_LDPLUSPLUS ${CMAKE_BINARY_DIR}/launch-CXX PARENT_SCOPE)
-  endif()
-endfunction()
-
-if(MSVC)
-  # Ccache does not support cl.exe-style arguments at this time.
-  return()
-endif()
-
-option(USE_CCACHE "Use ccache to speed up recompilation time" TRUE)
-if(USE_CCACHE)
-  use_ccache()
-endif()