[CMake] Minor cleanup to Xcode toolchain generation

[grp]

Summary

• Remove unused tool path check.
• Avoid PlistBuddy to avoid requiring macOS.

[beanz]

Removing the dead code is fine. Really not a fan of removing PlistBuddy.

Generally I'm not sure supporting building OS X binaries on non-Apple systems is a good idea, and using echo like this is less maintainable than using a tool that actually understands plists.

If you're cross building your Darwin compiler (and I *really* don't want to know if you are or how you're doing it... because lawyers). It seems to me that constructing the toolchain plist is something you might want to handle outside the LLVM build system.

[grp]

Makes sense. I'll cut it down to just the dead code.

tools/xcode-toolchain/CMakeLists.txt

 # Xcode 8 requires CompatibilityVersion 2
 set(COMPAT_VERSION 2)
 if(XCODE_VERSION VERSION_LESS 8.0.0)
   # Xcode 7.3 (the first version supporting external toolchains) requires
   # CompatibilityVersion 1
   set(COMPAT_VERSION 1)
 endif()
 
-execute_process(
-  COMMAND xcrun -find otool
-  OUTPUT_VARIABLE clang_path
-  OUTPUT_STRIP_TRAILING_WHITESPACE
-  ERROR_FILE /dev/null
-)
-string(REGEX MATCH "(.*/Toolchains)/.*" toolchains_match ${clang_path})
-if(NOT toolchains_match)
-  message(FATAL_ERROR "Could not identify toolchain dir")
-endif()
-set(toolchains_dir ${CMAKE_MATCH_1})
-
 set(LLVMToolchainDir "${CMAKE_INSTALL_PREFIX}/Toolchains/LLVM${PACKAGE_VERSION}.xctoolchain/")
 
 add_custom_command(OUTPUT ${LLVMToolchainDir}
                     COMMAND ${CMAKE_COMMAND} -E make_directory ${LLVMToolchainDir})
 
 add_custom_command(OUTPUT ${LLVMToolchainDir}/Info.plist
                   DEPENDS ${LLVMToolchainDir}
                   COMMAND ${CMAKE_COMMAND} -E remove ${LLVMToolchainDir}/Info.plist
-                  COMMAND /usr/libexec/PlistBuddy -c "Add:CFBundleIdentifier string org.llvm.${PACKAGE_VERSION}" "${LLVMToolchainDir}/Info.plist"
-                  COMMAND /usr/libexec/PlistBuddy -c "Add:CompatibilityVersion integer ${COMPAT_VERSION}" "${LLVMToolchainDir}/Info.plist"
+                  COMMAND echo "<?xml version=\"1.0\" encoding=\"UTF-8\"?>" >> "${LLVMToolchainDir}/Info.plist"
+                  COMMAND echo "<!DOCTYPE plist PUBLIC \"-//Apple//DTD PLIST 1.0//EN\" \"http://www.apple.com/DTDs/PropertyList-1.0.dtd\">" >> "${LLVMToolchainDir}/Info.plist"
+                  COMMAND echo "<plist version=\"1.0\">" >> "${LLVMToolchainDir}/Info.plist"
+                  COMMAND echo "<dict>" >> "${LLVMToolchainDir}/Info.plist"
+                  COMMAND echo "    <key>CFBundleIdentifier</key>" >> "${LLVMToolchainDir}/Info.plist"
+                  COMMAND echo "    <string>org.llvm.${PACKAGE_VERSION}</string>" >> "${LLVMToolchainDir}/Info.plist"
+                  COMMAND echo "    <key>CompatibilityVersion</key>" >> "${LLVMToolchainDir}/Info.plist"
+                  COMMAND echo "    <integer>${COMPAT_VERSION}</integer>" >> "${LLVMToolchainDir}/Info.plist"
+                  COMMAND echo "</dict>" >> "${LLVMToolchainDir}/Info.plist"
+                  COMMAND echo "</plist>" >> "${LLVMToolchainDir}/Info.plist"
+                  VERBATIM
                   )
 
 add_custom_target(install-xcode-toolchain
                   DEPENDS ${LLVMToolchainDir}/Info.plist
                   COMMAND "${CMAKE_COMMAND}" --build ${CMAKE_BINARY_DIR} --target all
                   COMMAND "${CMAKE_COMMAND}"
                           -DCMAKE_INSTALL_PREFIX=${LLVMToolchainDir}/usr/
                           -P "${CMAKE_BINARY_DIR}/cmake_install.cmake"