[CMake] Include pre-4.8 ccache error on Windows

Author: mrkajetanp

llvm/CMakeLists.txt

@@ -284,14 +284,22 @@ if(LLVM_CCACHE_BUILD)
       set(LLVM_CCACHE_PARAMS "CCACHE_CPP2=yes;CCACHE_HASHDIR=yes"
           CACHE STRING "Parameters to pass through to ccache")
 
-      set(launcher_params ${LLVM_CCACHE_PARAMS})
-      if (LLVM_CCACHE_MAXSIZE)
-        set(launcher_params CCACHE_MAXSIZE=${LLVM_CCACHE_MAXSIZE} ${launcher_params})
-      endif()
-      if (LLVM_CCACHE_DIR)
-        set(launcher_params CCACHE_DIR=${LLVM_CCACHE_DIR} ${launcher_params})
+      if(NOT CMAKE_SYSTEM_NAME MATCHES "Windows")
+        set(launcher_params ${LLVM_CCACHE_PARAMS})
+        if (LLVM_CCACHE_MAXSIZE)
+          set(launcher_params CCACHE_MAXSIZE=${LLVM_CCACHE_MAXSIZE} ${launcher_params})
+        endif()
+        if (LLVM_CCACHE_DIR)
+          set(launcher_params CCACHE_DIR=${LLVM_CCACHE_DIR} ${launcher_params})
+        endif()
+        set(launcher ${launcher_params} "${CCACHE_PROGRAM}")
+      else()
+        if(LLVM_CCACHE_MAXSIZE OR LLVM_CCACHE_DIR OR
+           NOT LLVM_CCACHE_PARAMS MATCHES "CCACHE_CPP2=yes;CCACHE_HASHDIR=yes")
+          message(FATAL_ERROR "Ccache configuration through CMake is not supported on Windows. Please use environment variables.")
+        endif()
+        set(launcher "${CCACHE_PROGRAM}")
       endif()
-      set(launcher ${launcher_params} "${CCACHE_PROGRAM}")
     else()
       set(LLVM_CCACHE_PARAMS "run_second_cpp=true;hash_dir=true"
           CACHE STRING "Parameters to pass through to ccache")