From b51347960c806c624d8fbc24b973aeceda3dd8ae Mon Sep 17 00:00:00 2001
From: Fangrui Song <i@maskray.me>
Date: Fri, 6 Apr 2018 00:26:53 -0700
Subject: [PATCH] Import cmake improvement by Daan De Meyer

---
 CMakeLists.txt                      |  88 +++++++++++++-------
 cmake/DownloadAndExtract7zip.cmake  |  59 ++++++-------
 cmake/DownloadAndExtractClang.cmake | 124 ++++++++++++++++++++++++++++
 cmake/DownloadAndExtractLLVM.cmake  | 112 -------------------------
 cmake/FindClang.cmake               |  33 +++++---
 5 files changed, 233 insertions(+), 183 deletions(-)
 create mode 100644 cmake/DownloadAndExtractClang.cmake
 delete mode 100644 cmake/DownloadAndExtractLLVM.cmake

diff --git a/CMakeLists.txt b/CMakeLists.txt
index f95f6171..52e26ebc 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -3,13 +3,14 @@ project(ccls LANGUAGES CXX)
 
 list(APPEND CMAKE_MODULE_PATH ${CMAKE_SOURCE_DIR}/cmake/)
 include(DefaultCMakeBuildType)
-include(DownloadAndExtractLLVM)
 
-set(CLANG_VERSION 6.0.0 CACHE STRING "Downloaded Clang version (6.0.0)")
-option(SYSTEM_CLANG "Use system Clang instead of downloading Clang" OFF)
+# Required libclang version
+set(LIBCLANG_VERSION 6.0.0 CACHE STRING "libclang version")
+set(LIBCLANG_DOWNLOAD_LOCATION ${CMAKE_BINARY_DIR} 
+    CACHE STRING "Downloaded libclang location")
+option(SYSTEM_LIBCLANG "Use system installation of libclang instead of \
+       downloading libclang" OFF)
 option(ASAN "Compile with address sanitizers" OFF)
-option(CLANG_CXX "Build with Clang C++ api required by some ccls \
-features (warning: not available in LLVM Windows downloads)" OFF)
 
 # Sources for the executable are specified at end of CMakeLists.txt
 add_executable(ccls "")
@@ -63,13 +64,6 @@ else()
                            $<$<CONFIG:Debug>:-fno-limit-debug-info>)
   endif()
 
-  if(CLANG_CXX)
-    # -Wno-comment: include/clang/Format/Format.h error: multi-line comment
-    # -fno-rtti: # Without -fno-rtti, some Clang C++ functions may report
-    # `undefined references to typeinfo`
-    target_compile_options(ccls PRIVATE -Wno-comment -fno-rtti)
-  endif()
-
   if(ASAN)
     target_compile_options(ccls PRIVATE -fsanitize=address,undefined)
     # target_link_libraries also takes linker flags
@@ -77,18 +71,23 @@ else()
   endif()
 endif()
 
-### Download Clang if required
+### Download libclang if required
 
-if(NOT SYSTEM_CLANG)
-  download_and_extract_llvm(${CLANG_VERSION})
+if(NOT SYSTEM_LIBCLANG)
+  message(STATUS "Using downloaded libclang")
+  
+  include(DownloadAndExtractClang)
+  download_and_extract_clang(${LIBCLANG_VERSION} ${LIBCLANG_DOWNLOAD_LOCATION})
   # Used by FindClang
   set(CLANG_ROOT ${DOWNLOADED_CLANG_DIR})
+else()
+  message(STATUS "Using system libclang")
 endif()
 
 ### Libraries
 
 # See cmake/FindClang.cmake
-find_package(Clang REQUIRED)
+find_package(Clang ${CLANG_VERSION} REQUIRED)
 target_link_libraries(ccls PRIVATE Clang::Clang)
 
 # Enable threading support
@@ -96,7 +95,9 @@ set(THREADS_PREFER_PTHREAD_FLAG ON)
 find_package(Threads REQUIRED)
 target_link_libraries(ccls PRIVATE Threads::Threads)
 
-if(${CMAKE_SYSTEM_NAME} MATCHES "Windows")
+if(${CMAKE_SYSTEM_NAME} STREQUAL Darwin)
+  target_link_libraries(ccls PRIVATE -lc++experimental)
+elseif(${CMAKE_SYSTEM_NAME} STREQUAL Windows)
 else()
   target_link_libraries(ccls PRIVATE -lstdc++fs)
 endif()
@@ -117,12 +118,6 @@ elseif(${CMAKE_SYSTEM_NAME} STREQUAL Windows)
   target_link_libraries(ccls PRIVATE Psapi)
 endif()
 
-if(CLANG_CXX)
-  # Clang C++ api uses ncurses
-  find_package(Curses REQUIRED)
-  target_link_libraries(ccls PRIVATE ${CURSES_LIBRARIES})
-endif()
-
 ### Definitions
 
 target_compile_definitions(ccls PRIVATE
@@ -131,10 +126,6 @@ target_compile_definitions(ccls PRIVATE
                            LOGURU_THREADNAME_WIDTH=13
                            DEFAULT_RESOURCE_DIRECTORY="${Clang_RESOURCE_DIR}")
 
-if(CLANG_CXX)
-  target_compile_definitions(ccls PRIVATE USE_CLANG_CXX=1 LOGURU_RTTI=0)
-endif()
-
 ### Includes
 
 target_include_directories(ccls PRIVATE
@@ -150,9 +141,8 @@ target_include_directories(ccls PRIVATE
 
 install(TARGETS ccls RUNTIME DESTINATION bin)
 
-# We don't need to install libclang on Windows if we are using downloaded LLVM
-# since libclang is distributed as a static library on Windows
-if(NOT SYSTEM_CLANG AND NOT ${CMAKE_SYSTEM_NAME} STREQUAL Windows)
+# TODO: install libclang.dll on Windows as well
+if(NOT SYSTEM_LIBCLANG AND NOT ${CMAKE_SYSTEM_NAME} STREQUAL Windows)
 
   if(${CMAKE_SYSTEM_NAME} MATCHES Linux|FreeBSD)
     set_property(TARGET ccls APPEND PROPERTY
@@ -167,6 +157,44 @@ if(NOT SYSTEM_CLANG AND NOT ${CMAKE_SYSTEM_NAME} STREQUAL Windows)
   install(FILES ${LIBCLANG_PLUS_SYMLINKS} DESTINATION lib)
 endif()
 
+# Allow running from build Windows by copying libclang.dll to build directory
+if(NOT SYSTEM_LIBCLANG AND ${CMAKE_SYSTEM_NAME} STREQUAL Windows)
+  add_custom_command(TARGET ccls
+                     POST_BUILD
+                     COMMAND ${CMAKE_COMMAND} -E copy 
+                     ${DOWNLOADED_CLANG_DIR}/bin/libclang.dll 
+                     $<TARGET_FILE_DIR:ccls>
+                     COMMENT "Copying libclang.dll to build directory ...")
+endif()
+
+### Tools
+
+# We use glob here since source files are already manually added with
+# target_sources further down
+file(GLOB SOURCES src/*.cc src/*.h src/serializers/*.cc src/serializers/*.h
+                  src/messages/*.h src/messages/*.cc)
+
+if(Clang_FORMAT AND ${Clang_VERSION} STREQUAL 6.0.0)
+  add_custom_target(format
+                    COMMAND ${Clang_FORMAT} -i ${SOURCES}
+                    # .clang-format is located in the ccls root project dir
+                    WORKING_DIRECTORY ${CMAKE_SOURCE_DIR}
+                    COMMENT "Running clang-format ...")
+else()
+  # Set error message depending on which condition was false
+  if (NOT Clang_FORMAT)
+    set(Clang_FORMAT_ERROR "Error: clang-format executable not found")
+  elseif(NOT ${Clang_VERSION} STREQUAL 6.0.0)
+    set(Clang_FORMAT_ERROR "Error: clang-format version does not match \
+6.0.0. Due to differences in clang-format output between versions we only \
+support clang-format 6.0.0")
+  endif()
+
+  add_custom_target(format 
+                    COMMAND ${CMAKE_COMMAND} -E cmake_echo_color --red --bold
+                    ${Clang_FORMAT_ERROR})
+endif()
+
 ### Sources
 
 target_sources(ccls PRIVATE third_party/siphash.cc)
diff --git a/cmake/DownloadAndExtract7zip.cmake b/cmake/DownloadAndExtract7zip.cmake
index f3257e6b..72bc879d 100644
--- a/cmake/DownloadAndExtract7zip.cmake
+++ b/cmake/DownloadAndExtract7zip.cmake
@@ -1,51 +1,52 @@
 # Downloads and extracts the 7-Zip MSI installer from https://www.7-zip.org/. 
 # 
 # Returns the extracted 7-Zip directory in DOWNLOADED_7ZIP_DIR
-#
-# Downloads 7-Zip to extract LLVM if it isn't available in the PATH
-function(download_and_extract_7zip)
+function(download_and_extract_7zip 7ZIP_DOWNLOAD_LOCATION)
 
 set(7ZIP_VERSION 1801)
 set(7ZIP_EXT .msi)
 set(7ZIP_NAME 7z${7ZIP_VERSION}-x64)
 set(7ZIP_FULL_NAME ${7ZIP_NAME}${7ZIP_EXT})
 
-set(7ZIP_FILE ${CMAKE_BINARY_DIR}/${7ZIP_FULL_NAME})
-set(7ZIP_EXTRACT_DIR ${CMAKE_BINARY_DIR}/${7ZIP_NAME})
+set(7ZIP_FILE ${7ZIP_DOWNLOAD_LOCATION}/${7ZIP_FULL_NAME})
+set(7ZIP_EXTRACT_DIR ${7ZIP_DOWNLOAD_LOCATION}/${7ZIP_NAME})
 set(7ZIP_URL https://www.7-zip.org/a/${7ZIP_FULL_NAME})
 
+# Exit if 7-Zip is already downloaded and extracted
+find_program(7ZIP_EXECUTABLE 7z NO_DEFAULT_PATH
+             PATHS ${7ZIP_EXTRACT_DIR}/Files/7-Zip)
+if(7ZIP_EXECUTABLE)
+  message(STATUS "7-Zip already downloaded")
+  return()
+endif()
+
+message(STATUS "Downloading 7-Zip ${7ZIP_VERSION} (${7ZIP_URL}) ...")
+file(DOWNLOAD ${7ZIP_URL} ${7ZIP_FILE})
+
+find_program(MSIEXEC_EXECUTABLE msiexec)
+if(NOT MSIEXEC_EXECUTABLE)
+  message(FATAL_ERROR "Unable to find msiexec (required to extract 7-Zip msi \
+installer). Install 7-Zip yourself and make sure it is available in the path")    
+endif()
+
+message(STATUS "Extracting downloaded 7-Zip ...")
+
 # msiexec requires Windows path separators (\)
 file(TO_NATIVE_PATH ${7ZIP_FILE} 7ZIP_FILE)
 file(TO_NATIVE_PATH ${7ZIP_EXTRACT_DIR} 7ZIP_EXTRACT_DIR) 
 
-if(NOT EXISTS ${7ZIP_FILE})
-  message(STATUS "Downloading 7-Zip ${7ZIP_VERSION} (${7ZIP_URL}) ...")
-  file(DOWNLOAD ${7ZIP_URL} ${7ZIP_FILE})
-endif()
-
-if(NOT EXISTS ${7ZIP_EXTRACT_DIR})
-
-  find_program(MSIEXEC_EXECUTABLE msiexec)
-  if(NOT MSIEXEC_EXECUTABLE)
-    message(FATAL_ERROR "Unable to find msiexec (required to extract 7-Zip msi \
-installer). Install 7-Zip yourself and make sure it is available in the path")    
-  endif()
-
-  message(STATUS "Extracting downloaded 7-Zip ...")
-
-  # msiexec with /a option allows extraction of msi installers without requiring
-  # admin privileges. We use this to extract the 7-Zip installer without
-  # requiring any actions from the user
-  execute_process(COMMAND ${MSIEXEC_EXECUTABLE} /a ${7ZIP_FILE} /qn
-                          TARGETDIR=${7ZIP_EXTRACT_DIR}
-                  OUTPUT_QUIET)     
-endif()
+# msiexec with /a option allows extraction of msi installers without requiring
+# admin privileges. We use this to extract the 7-Zip installer without
+# requiring any actions from the user
+execute_process(COMMAND ${MSIEXEC_EXECUTABLE} /a ${7ZIP_FILE} /qn
+                        TARGETDIR=${7ZIP_EXTRACT_DIR}
+                WORKING_DIRECTORY ${7ZIP_DOWNLOAD_LOCATION}
+                OUTPUT_QUIET)     
 
 # Convert back to CMake separators (/) before returning
 file(TO_CMAKE_PATH ${7ZIP_EXTRACT_DIR} 7ZIP_EXTRACT_DIR)
 
-# Actual directory is nested inside the extract directory. We return the nested
-# directory instead of the extract directory
+# Actual 7-Zip directory is nested inside the extract directory.
 set(DOWNLOADED_7ZIP_DIR ${7ZIP_EXTRACT_DIR}/Files/7-Zip PARENT_SCOPE)
 
 endfunction()
\ No newline at end of file
diff --git a/cmake/DownloadAndExtractClang.cmake b/cmake/DownloadAndExtractClang.cmake
new file mode 100644
index 00000000..ee5feaa7
--- /dev/null
+++ b/cmake/DownloadAndExtractClang.cmake
@@ -0,0 +1,124 @@
+# Downloads and extracts the Clang archive for the current system from
+# https://releases.llvm.org
+#
+# Returns the extracted Clang archive directory in DOWNLOADED_CLANG_DIR
+#
+# Downloads 7-Zip to extract Clang if it isn't available in the PATH
+function(download_and_extract_clang CLANG_VERSION CLANG_DOWNLOAD_LOCATION)
+
+set(CLANG_ARCHIVE_EXT .tar.xz)
+
+if(${CMAKE_SYSTEM_NAME} STREQUAL Linux)
+
+  set(CLANG_ARCHIVE_NAME
+      clang+llvm-${CLANG_VERSION}-x86_64-linux-gnu-ubuntu-14.04)
+
+elseif(${CMAKE_SYSTEM_NAME} STREQUAL Darwin)
+
+  set(CLANG_ARCHIVE_NAME clang+llvm-${CLANG_VERSION}-x86_64-apple-darwin)
+
+elseif(${CMAKE_SYSTEM_NAME} STREQUAL Windows)
+
+  set(CLANG_ARCHIVE_NAME LLVM-${CLANG_VERSION}-win64)
+  set(CLANG_ARCHIVE_EXT .exe)
+
+elseif(${CMAKE_SYSTEM_NAME} STREQUAL FreeBSD)
+
+  if(${CLANG_VERSION} STREQUAL 6.0.0)
+    set(CLANG_ARCHIVE_NAME clang+llvm-${CLANG_VERSION}-amd64-unknown-freebsd-10)
+  else()
+    set(CLANG_ARCHIVE_NAME clang+llvm-${CLANG_VERSION}-amd64-unknown-freebsd10)
+  endif()
+
+endif()
+
+set(CLANG_ARCHIVE_FULL_NAME ${CLANG_ARCHIVE_NAME}${CLANG_ARCHIVE_EXT})
+set(CLANG_ARCHIVE_FILE ${CLANG_DOWNLOAD_LOCATION}/${CLANG_ARCHIVE_FULL_NAME})
+set(CLANG_ARCHIVE_EXTRACT_DIR ${CLANG_DOWNLOAD_LOCATION}/${CLANG_ARCHIVE_NAME})
+set(CLANG_ARCHIVE_URL
+    https://releases.llvm.org/${CLANG_VERSION}/${CLANG_ARCHIVE_FULL_NAME})
+set(CLANG_ARCHIVE_HASH_FILE
+    ${CMAKE_SOURCE_DIR}/clang_archive_hashes/${CLANG_ARCHIVE_FULL_NAME}.SHA256)
+
+# Exit if Clang is already downloaded and extracted
+set(CLANG_ROOT ${CLANG_ARCHIVE_EXTRACT_DIR})
+find_package(Clang ${CLANG_VERSION} QUIET)
+if(Clang_FOUND)
+  message(STATUS "Clang already downloaded")
+  set(DOWNLOADED_CLANG_DIR ${CLANG_ARCHIVE_EXTRACT_DIR} PARENT_SCOPE)
+  return()
+endif()
+
+if(NOT CLANG_ARCHIVE_NAME)
+  message(FATAL_ERROR "No Clang archive url specified for current platform \
+(${CMAKE_SYSTEM_NAME}). Please file an issue to get it added.")
+endif()
+
+if(NOT EXISTS ${CLANG_ARCHIVE_HASH_FILE})
+  message(FATAL_ERROR "No SHA256 hash available for the current platform \
+(${CMAKE_SYSTEM_NAME}) + clang version (${CLANG_VERSION}) combination. Please \
+file an issue to get it added.")
+endif()
+
+# Download Clang archive
+message(STATUS "Downloading Clang ${CLANG_VERSION} (${CLANG_ARCHIVE_URL}) ...")
+file(DOWNLOAD ${CLANG_ARCHIVE_URL} ${CLANG_ARCHIVE_FILE}
+     STATUS CLANG_ARCHIVE_DOWNLOAD_RESULT)
+
+# Abort if download failed
+list(GET ${CLANG_ARCHIVE_DOWNLOAD_RESULT} 0 ERROR_CODE)
+if(${ERROR_CODE})
+  list(GET ${CLANG_ARCHIVE_DOWNLOAD_RESULT} 1 ERROR_STRING)
+  message(FATAL_ERROR ${ERROR_STRING})
+endif()
+
+# Retrieve expected hash from file and strip newline
+file(READ ${CLANG_ARCHIVE_HASH_FILE} CLANG_ARCHIVE_EXPECTED_HASH)
+string(STRIP ${CLANG_ARCHIVE_EXPECTED_HASH} CLANG_ARCHIVE_EXPECTED_HASH)
+# Calculate actual hash
+file(SHA256 ${CLANG_ARCHIVE_FILE} CLANG_ARCHIVE_HASH)
+# Abort if hashes do not match
+if(NOT ${CLANG_ARCHIVE_EXPECTED_HASH} STREQUAL ${CLANG_ARCHIVE_HASH})
+  message(FATAL_ERROR "SHA256 hash of downloaded Clang does not match \
+expected hash. Remove the build directory and try running CMake again. If this \
+keeps happening, file an issue to report the problem.")
+endif()
+
+if(${CLANG_ARCHIVE_EXT} STREQUAL .exe)
+  # Download and extract 7-zip if not found in PATH
+  find_program(7ZIP_EXECUTABLE 7z)
+  if(NOT 7ZIP_EXECUTABLE)
+    message(STATUS "7-Zip not found in PATH")
+
+    include(DownloadAndExtract7zip)
+    download_and_extract_7zip(${CLANG_DOWNLOAD_LOCATION})
+    find_program(7ZIP_EXECUTABLE 7z NO_DEFAULT_PATH
+                  PATHS ${DOWNLOADED_7ZIP_DIR})
+  else()
+    message(STATUS "7-Zip found in PATH")
+  endif()
+
+  message(STATUS "Extracting downloaded Clang with 7-Zip ...")
+
+  # Avoid running the Clang installer by extracting the exe with 7-Zip
+  execute_process(COMMAND ${7ZIP_EXECUTABLE} x
+                          -o${CLANG_ARCHIVE_EXTRACT_DIR}
+                          -xr!$PLUGINSDIR ${CLANG_ARCHIVE_FILE}
+                  WORKING_DIRECTORY ${CLANG_DOWNLOAD_LOCATION}
+                  OUTPUT_QUIET)
+
+elseif(${CLANG_ARCHIVE_EXT} STREQUAL .tar.xz)
+  message(STATUS "Extracting downloaded Clang with CMake built-in tar ...")
+
+  # CMake has builtin support for tar via the -E flag
+  execute_process(COMMAND ${CMAKE_COMMAND} -E tar -xf ${CLANG_ARCHIVE_FILE}
+                  # Specify working directory to allow running cmake from
+                  # everywhere
+                  # (example: cmake -H"$HOME/ccls" -B"$home/ccls/build")
+                  WORKING_DIRECTORY ${CLANG_DOWNLOAD_LOCATION}
+                  OUTPUT_QUIET)
+endif()
+
+set(DOWNLOADED_CLANG_DIR ${CLANG_ARCHIVE_EXTRACT_DIR} PARENT_SCOPE)
+
+endfunction()
diff --git a/cmake/DownloadAndExtractLLVM.cmake b/cmake/DownloadAndExtractLLVM.cmake
deleted file mode 100644
index 4a122e35..00000000
--- a/cmake/DownloadAndExtractLLVM.cmake
+++ /dev/null
@@ -1,112 +0,0 @@
-# Downloads and extracts the LLVM archive for the current system from
-# https://releases.llvm.org
-#
-# Returns the extracted LLVM archive directory in DOWNLOADED_CLANG_DIR
-#
-# Downloads 7-Zip to extract LLVM if it isn't available in the PATH
-function(download_and_extract_llvm CLANG_VERSION)
-
-include(DownloadAndExtract7zip)
-
-set(CLANG_ARCHIVE_EXT .tar.xz)
-
-if(${CMAKE_SYSTEM_NAME} STREQUAL Linux)
-
-  set(CLANG_ARCHIVE_NAME
-      clang+llvm-${CLANG_VERSION}-x86_64-linux-gnu-ubuntu-14.04)
-
-elseif(${CMAKE_SYSTEM_NAME} STREQUAL Darwin)
-
-  set(CLANG_ARCHIVE_NAME clang+llvm-${CLANG_VERSION}-x86_64-apple-darwin)
-
-elseif(${CMAKE_SYSTEM_NAME} STREQUAL Windows)
-
-  set(CLANG_ARCHIVE_NAME LLVM-${CLANG_VERSION}-win64)
-  set(CLANG_ARCHIVE_EXT .exe)
-
-elseif(${CMAKE_SYSTEM_NAME} STREQUAL FreeBSD)
-
-  if(${CLANG_VERSION} STREQUAL 6.0.0)
-    set(CLANG_ARCHIVE_NAME clang+llvm-${CLANG_VERSION}-amd64-unknown-freebsd-10)
-  else()
-    set(CLANG_ARCHIVE_NAME clang+llvm-${CLANG_VERSION}-amd64-unknown-freebsd10)
-  endif()
-endif()
-
-if(NOT CLANG_ARCHIVE_NAME)
-  message(FATAL_ERROR "No LLVM archive url specified for current platform \
-(${CMAKE_SYSTEM_NAME}). Please file an issue to get it added.")
-endif()
-
-set(CLANG_ARCHIVE_FULL_NAME ${CLANG_ARCHIVE_NAME}${CLANG_ARCHIVE_EXT})
-set(CLANG_ARCHIVE_FILE ${CMAKE_BINARY_DIR}/${CLANG_ARCHIVE_FULL_NAME})
-set(CLANG_ARCHIVE_EXTRACT_DIR ${CMAKE_BINARY_DIR}/${CLANG_ARCHIVE_NAME})
-set(CLANG_ARCHIVE_URL
-    https://releases.llvm.org/${CLANG_VERSION}/${CLANG_ARCHIVE_FULL_NAME})
-set(CLANG_ARCHIVE_HASH_FILE
-    ${CMAKE_SOURCE_DIR}/clang_archive_hashes/${CLANG_ARCHIVE_FULL_NAME}.SHA256)
-
-if(NOT EXISTS ${CLANG_ARCHIVE_HASH_FILE})
-  message(FATAL_ERROR "No SHA256 hash available for the current platform \
-(${CMAKE_SYSTEM_NAME}) + clang version (${CLANG_VERSION}) combination. Please \
-file an issue to get it added.")
-endif()
-
-file(READ ${CLANG_ARCHIVE_HASH_FILE} CLANG_ARCHIVE_EXPECTED_HASH)
-# Strip newline
-string(STRIP ${CLANG_ARCHIVE_EXPECTED_HASH} CLANG_ARCHIVE_EXPECTED_HASH)
-
-if(NOT EXISTS ${CLANG_ARCHIVE_FILE})
-  message(STATUS "Downloading LLVM ${CLANG_VERSION} (${CLANG_ARCHIVE_URL}) ...")
-  file(DOWNLOAD ${CLANG_ARCHIVE_URL} ${CLANG_ARCHIVE_FILE}
-       STATUS CLANG_ARCHIVE_DOWNLOAD_RESULT)
-
-  list(GET ${CLANG_ARCHIVE_DOWNLOAD_RESULT} 0 ERROR_CODE)
-  if(${ERROR_CODE})
-    list(GET ${CLANG_ARCHIVE_DOWNLOAD_RESULT} 1 ERROR_STRING)
-    message(FATAL_ERROR ${ERROR_STRING})
-  endif()
-endif()
-
-file(SHA256 ${CLANG_ARCHIVE_FILE} CLANG_ARCHIVE_HASH)
-if(NOT ${CLANG_ARCHIVE_EXPECTED_HASH} STREQUAL ${CLANG_ARCHIVE_HASH})
-  message(FATAL_ERROR "SHA256 hash of downloaded LLVM does not match \
-expected hash. Remove the build directory and try running CMake again. If this \
-keeps happening, file an issue to report the problem.")
-endif()
-
-if(NOT EXISTS ${CLANG_ARCHIVE_EXTRACT_DIR})
-  if(${CLANG_ARCHIVE_EXT} STREQUAL .exe)
-    find_program(7ZIP_EXECUTABLE 7z)
-
-    if(NOT 7ZIP_EXECUTABLE)
-      message(STATUS "7-Zip not found in PATH")
-      download_and_extract_7zip()
-      find_program(7ZIP_EXECUTABLE 7z NO_DEFAULT_PATH
-                   PATHS ${DOWNLOADED_7ZIP_DIR})
-    else()
-      message(STATUS "7-Zip found in PATH")
-    endif()
-
-    message(STATUS "Extracting downloaded LLVM with 7-Zip ...")
-
-    # Avoid running the LLVM installer by extracting the exe with 7-Zip
-    execute_process(COMMAND ${7ZIP_EXECUTABLE} x
-                            -o${CLANG_ARCHIVE_EXTRACT_DIR}
-                            -xr!$PLUGINSDIR ${CLANG_ARCHIVE_FILE}
-                    OUTPUT_QUIET)
-  elseif(${CLANG_ARCHIVE_EXT} STREQUAL .tar.xz)
-    message(STATUS "Extracting downloaded LLVM with CMake built-in tar ...")
-    # CMake has builtin support for tar via the -E flag
-    execute_process(COMMAND ${CMAKE_COMMAND} -E tar -xf ${CLANG_ARCHIVE_FILE}
-                    # Extract to here to allow running cmake from everywhere
-                    WORKING_DIRECTORY ${CMAKE_BINARY_DIR}
-                    OUTPUT_QUIET)
-  endif()
-endif()
-
-# CMake functions have no return values so we just lift our return variable to
-# the parent scope
-set(DOWNLOADED_CLANG_DIR ${CLANG_ARCHIVE_EXTRACT_DIR} PARENT_SCOPE)
-
-endfunction()
diff --git a/cmake/FindClang.cmake b/cmake/FindClang.cmake
index c8e0d247..f21fb57b 100644
--- a/cmake/FindClang.cmake
+++ b/cmake/FindClang.cmake
@@ -2,12 +2,13 @@
 # FindClang
 # ---------
 #
-# Find Clang and LLVM libraries required by cquery
+# Find Clang and LLVM libraries required by ccls
 #
 # Results are reported in the following variables::
 #
 #   Clang_FOUND         - True if headers and requested libraries were found
 #   Clang_EXECUTABLE    - Clang executable
+#   Clang_FORMAT        - Clang-format executable
 #   Clang_RESOURCE_DIR  - Clang resource directory
 #   Clang_VERSION       - Clang version as reported by Clang executable
 #
@@ -32,8 +33,8 @@
 
 macro(_Clang_find_library VAR NAME)
   # Windows needs lib prefix
-  if (CLANG_ROOT)    
-    find_library(${VAR} NAMES ${NAME} lib${NAME} 
+  if (CLANG_ROOT)
+    find_library(${VAR} NAMES ${NAME} lib${NAME}
                  NO_DEFAULT_PATH PATHS ${CLANG_ROOT} PATH_SUFFIXES lib)
   else()
     find_library(${VAR} NAMES ${NAME} lib${NAME})
@@ -42,7 +43,7 @@ endmacro()
 
 macro(_Clang_find_path VAR INCLUDE_FILE)
   if (CLANG_ROOT)
-    find_path(${VAR} ${INCLUDE_FILE} 
+    find_path(${VAR} ${INCLUDE_FILE}
               NO_DEFAULT_PATH PATHS ${CLANG_ROOT} PATH_SUFFIXES include)
   else()
     find_path(${VAR} ${INCLUDE_FILE})
@@ -51,7 +52,7 @@ endmacro()
 
 macro(_Clang_find_program VAR NAME)
   if (CLANG_ROOT)
-    find_program(${VAR} ${NAME} 
+    find_program(${VAR} ${NAME}
                  NO_DEFAULT_PATH PATHS ${CLANG_ROOT} PATH_SUFFIXES bin)
   else()
     find_program(${VAR} ${NAME})
@@ -73,14 +74,14 @@ endmacro()
 
 ### Start
 
-set(_Clang_REQUIRED_VARS Clang_LIBRARY Clang_INCLUDE_DIR Clang_EXECUTABLE 
+set(_Clang_REQUIRED_VARS Clang_LIBRARY Clang_INCLUDE_DIR Clang_EXECUTABLE
                          Clang_RESOURCE_DIR Clang_VERSION)
 
 _Clang_find_library(Clang_LIBRARY clang)
 _Clang_find_path(Clang_INCLUDE_DIR clang-c/Index.h)
 
 if(CLANG_CXX)
-  # The order is derived by topological sorting LINK_LIBS in 
+  # The order is derived by topological sorting LINK_LIBS in
   # clang/lib/*/CMakeLists.txt
   _Clang_find_and_add_cxx_lib(clangFormat clang/Format/Format.h)
   _Clang_find_and_add_cxx_lib(clangToolingCore clang/Tooling/Core/Diagnostic.h)
@@ -96,16 +97,24 @@ if(CLANG_CXX)
   _Clang_find_and_add_cxx_lib(LLVMDemangle llvm/Demangle/Demangle.h)
 endif()
 
+_Clang_find_program(Clang_FORMAT clang-format)
 _Clang_find_program(Clang_EXECUTABLE clang)
 if(Clang_EXECUTABLE)
   # Find Clang resource directory with Clang executable
-  execute_process(COMMAND ${Clang_EXECUTABLE} -print-resource-dir 
+  execute_process(COMMAND ${Clang_EXECUTABLE} -print-resource-dir
+                  RESULT_VARIABLE _Clang_FIND_RESOURCE_DIR_RESULT
                   OUTPUT_VARIABLE Clang_RESOURCE_DIR
+                  ERROR_VARIABLE _Clang_FIND_RESOURCE_DIR_ERROR
                   OUTPUT_STRIP_TRAILING_WHITESPACE)
 
+  if(_Clang_FIND_RESOURCE_DIR_RESULT)
+    message(FATAL_ERROR "Error retrieving Clang resource directory with Clang \
+executable. Output:\n ${_Clang_FIND_RESOURCE_DIR_ERROR}")
+  endif()
+
   # Find Clang version
   set(_Clang_VERSION_REGEX "([0-9]+)\\.([0-9]+)\\.([0-9]+)")
-  execute_process(COMMAND ${Clang_EXECUTABLE} --version 
+  execute_process(COMMAND ${Clang_EXECUTABLE} --version
                   OUTPUT_VARIABLE Clang_VERSION)
   string(REGEX MATCH ${_Clang_VERSION_REGEX} Clang_VERSION ${Clang_VERSION})
 endif()
@@ -122,8 +131,8 @@ if(Clang_FOUND AND NOT TARGET Clang::Clang)
   set(_Clang_INCLUDE_DIRS ${Clang_INCLUDE_DIR} ${_Clang_CXX_INCLUDE_DIRS})
 
   add_library(Clang::Clang INTERFACE IMPORTED)
-  set_property(TARGET Clang::Clang PROPERTY 
+  set_property(TARGET Clang::Clang PROPERTY
                INTERFACE_LINK_LIBRARIES ${_Clang_LIBRARIES})
-  set_property(TARGET Clang::Clang PROPERTY 
-               INTERFACE_INCLUDE_DIRECTORIES ${_Clang_INCLUDE_DIRS})  
+  set_property(TARGET Clang::Clang PROPERTY
+               INTERFACE_INCLUDE_DIRECTORIES ${_Clang_INCLUDE_DIRS})
 endif()