cmake: support ccache with Xcode generator

CMakeLists.txt

@@ -477,7 +477,7 @@ OCV_OPTION(INSTALL_TESTS            "Install accuracy and performance test binar
 
 # OpenCV build options
 # ===================================================
-OCV_OPTION(ENABLE_CCACHE              "Use ccache"                                               (UNIX AND NOT IOS AND (CMAKE_GENERATOR MATCHES "Makefile" OR CMAKE_GENERATOR MATCHES "Ninja")) )
+OCV_OPTION(ENABLE_CCACHE              "Use ccache"                                               (UNIX AND (CMAKE_GENERATOR MATCHES "Makefile" OR CMAKE_GENERATOR MATCHES "Ninja" OR CMAKE_GENERATOR MATCHES "Xcode")) )
 OCV_OPTION(ENABLE_PRECOMPILED_HEADERS "Use precompiled headers"                                  MSVC IF (MSVC OR (NOT IOS AND NOT CMAKE_CROSSCOMPILING) ) )
 OCV_OPTION(ENABLE_SOLUTION_FOLDERS    "Solution folder in Visual Studio or in other IDEs"        (MSVC_IDE OR CMAKE_GENERATOR MATCHES Xcode) )
 OCV_OPTION(ENABLE_PROFILING           "Enable profiling in the GCC compiler (Add flags: -g -pg)" OFF  IF CV_GCC )

cmake/OpenCVCompilerOptions.cmake

@@ -8,13 +8,27 @@ function(access_CMAKE_COMPILER_IS_CCACHE)
   endif()
 endfunction()
 variable_watch(CMAKE_COMPILER_IS_CCACHE access_CMAKE_COMPILER_IS_CCACHE)
-if(ENABLE_CCACHE AND NOT OPENCV_COMPILER_IS_CCACHE AND NOT CMAKE_GENERATOR MATCHES "Xcode")
+if(ENABLE_CCACHE AND NOT OPENCV_COMPILER_IS_CCACHE)
   # This works fine with Unix Makefiles and Ninja generators
   find_host_program(CCACHE_PROGRAM ccache)
   if(CCACHE_PROGRAM)
     message(STATUS "Looking for ccache - found (${CCACHE_PROGRAM})")
     get_property(__OLD_RULE_LAUNCH_COMPILE GLOBAL PROPERTY RULE_LAUNCH_COMPILE)
-    if(__OLD_RULE_LAUNCH_COMPILE)
+    if(CMAKE_GENERATOR MATCHES "Xcode")
+      configure_file("${CMAKE_CURRENT_LIST_DIR}/templates/xcode-launch-c.in" "${CMAKE_BINARY_DIR}/xcode-launch-c")
+      configure_file("${CMAKE_CURRENT_LIST_DIR}/templates/xcode-launch-cxx.in" "${CMAKE_BINARY_DIR}/xcode-launch-cxx")
+      execute_process(COMMAND chmod a+rx
+          "${CMAKE_BINARY_DIR}/xcode-launch-c"
+          "${CMAKE_BINARY_DIR}/xcode-launch-cxx"
+      )
+      # Xcode project attributes
+      set(CMAKE_XCODE_ATTRIBUTE_CC         "${CMAKE_BINARY_DIR}/xcode-launch-c")
+      set(CMAKE_XCODE_ATTRIBUTE_CXX        "${CMAKE_BINARY_DIR}/xcode-launch-cxx")
+      set(CMAKE_XCODE_ATTRIBUTE_LD         "${CMAKE_BINARY_DIR}/xcode-launch-c")
+      set(CMAKE_XCODE_ATTRIBUTE_LDPLUSPLUS "${CMAKE_BINARY_DIR}/xcode-launch-cxx")
+      set(OPENCV_COMPILER_IS_CCACHE 1)
+      message(STATUS "ccache: enable support through Xcode project properties")
+    elseif(__OLD_RULE_LAUNCH_COMPILE)
       message(STATUS "Can't replace CMake compiler launcher")
     else()
       set_property(GLOBAL PROPERTY RULE_LAUNCH_COMPILE "${CCACHE_PROGRAM}")

cmake/templates/xcode-launch-c.in

@@ -0,0 +1,11 @@
+#!/bin/sh
+# https://crascit.com/2016/04/09/using-ccache-with-cmake/
+
+# Xcode generator doesn't include the compiler as the
+# first argument, Ninja and Makefiles do. Handle both cases.
+if [[ "$1" = "${CMAKE_C_COMPILER}" ]] ; then
+    shift
+fi
+
+export CCACHE_CPP2=true
+exec "${CCACHE_PROGRAM}" "${CMAKE_C_COMPILER}" "$@"

cmake/templates/xcode-launch-cxx.in

@@ -0,0 +1,11 @@
+#!/bin/sh
+# https://crascit.com/2016/04/09/using-ccache-with-cmake/
+
+# Xcode generator doesn't include the compiler as the
+# first argument, Ninja and Makefiles do. Handle both cases.
+if [[ "$1" = "${CMAKE_CXX_COMPILER}" ]] ; then
+    shift
+fi
+
+export CCACHE_CPP2=true
+exec "${CCACHE_PROGRAM}" "${CMAKE_CXX_COMPILER}" "$@"

platforms/ios/cmake/Toolchains/common-ios-toolchain.cmake

@@ -160,10 +160,20 @@ set(CMAKE_CXX_COMPILER_ABI ELF)
 set(CMAKE_CXX_COMPILER_WORKS TRUE)
 set(CMAKE_C_COMPILER_WORKS TRUE)
 
-# Search for programs in the build host directories
-set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM ONLY)
-#   for libraries and headers in the target directories
-set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
-set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
+if(NOT CMAKE_FIND_ROOT_PATH_MODE_LIBRARY)
+  set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
+endif()
+
+if(NOT CMAKE_FIND_ROOT_PATH_MODE_INCLUDE)
+  set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
+endif()
+
+if(NOT CMAKE_FIND_ROOT_PATH_MODE_PACKAGE)
+  set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)
+endif()
+
+if(NOT CMAKE_FIND_ROOT_PATH_MODE_PROGRAM)
+  set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
+endif()
 
 toolchain_save_config(IOS_ARCH IPHONEOS_DEPLOYMENT_TARGET)