CMake: Don't use existing third-party sources by default.

Introduce ALLOW_EXISTING_SRC_DIR option, turned off by default.

The Homebrew formula, which downloads and extracts the third-party
dependency sources before starting the build, would turn this option
ON.

third-party/CMakeLists.txt

@@ -22,6 +22,8 @@ option(USE_BUNDLED_MSGPACK "Use the bundled msgpack." ${USE_BUNDLED})
 option(USE_BUNDLED_LUAJIT "Use the bundled version of luajit." ${USE_BUNDLED})
 option(USE_BUNDLED_LUAROCKS "Use the bundled version of luarocks." ${USE_BUNDLED})
 
+option(USE_EXISTING_SRC_DIR "Skip download of deps sources in case of existing source directory." OFF)
+
 if(UNIX)
   find_program(MAKE_PRG NAMES gmake make)
   if(MAKE_PRG)

third-party/cmake/BuildJeMalloc.cmake

@@ -13,6 +13,7 @@ ExternalProject_Add(jemalloc
     -DURL=${JEMALLOC_URL}
     -DEXPECTED_SHA256=${JEMALLOC_SHA256}
     -DTARGET=jemalloc
+    -DUSE_EXISTING_SRC_DIR=${USE_EXISTING_SRC_DIR}
     -P ${CMAKE_CURRENT_SOURCE_DIR}/cmake/DownloadAndExtractFile.cmake
   BUILD_IN_SOURCE 1
   CONFIGURE_COMMAND ${DEPS_BUILD_DIR}/src/jemalloc/configure --enable-cc-silence

third-party/cmake/BuildLibtermkey.cmake

@@ -14,6 +14,7 @@ ExternalProject_Add(libtermkey
     -DURL=${LIBTERMKEY_URL}
     -DEXPECTED_SHA256=${LIBTERMKEY_SHA256}
     -DTARGET=libtermkey
+    -DUSE_EXISTING_SRC_DIR=${USE_EXISTING_SRC_DIR}
     -P ${CMAKE_CURRENT_SOURCE_DIR}/cmake/DownloadAndExtractFile.cmake
   CONFIGURE_COMMAND ""
   BUILD_IN_SOURCE 1

third-party/cmake/BuildLibuv.cmake

@@ -28,6 +28,7 @@ function(BuildLibuv)
       -DURL=${LIBUV_URL}
       -DEXPECTED_SHA256=${LIBUV_SHA256}
       -DTARGET=${_libuv_TARGET}
+      -DUSE_EXISTING_SRC_DIR=${USE_EXISTING_SRC_DIR}
       -P ${CMAKE_CURRENT_SOURCE_DIR}/cmake/DownloadAndExtractFile.cmake
     CONFIGURE_COMMAND "${_libuv_CONFIGURE_COMMAND}"
     BUILD_COMMAND "${_libuv_BUILD_COMMAND}"

third-party/cmake/BuildLibvterm.cmake

@@ -13,6 +13,7 @@ ExternalProject_Add(libvterm
     -DURL=${LIBVTERM_URL}
     -DEXPECTED_SHA256=${LIBVTERM_SHA256}
     -DTARGET=libvterm
+    -DUSE_EXISTING_SRC_DIR=${USE_EXISTING_SRC_DIR}
     -P ${CMAKE_CURRENT_SOURCE_DIR}/cmake/DownloadAndExtractFile.cmake
   CONFIGURE_COMMAND ""
   BUILD_IN_SOURCE 1

third-party/cmake/BuildLuajit.cmake

@@ -27,6 +27,7 @@ function(BuildLuajit)
       -DURL=${LUAJIT_URL}
       -DEXPECTED_SHA256=${LUAJIT_SHA256}
       -DTARGET=${_luajit_TARGET}
+      -DUSE_EXISTING_SRC_DIR=${USE_EXISTING_SRC_DIR}
       -P ${CMAKE_CURRENT_SOURCE_DIR}/cmake/DownloadAndExtractFile.cmake
     CONFIGURE_COMMAND "${_luajit_CONFIGURE_COMMAND}"
     BUILD_IN_SOURCE 1

third-party/cmake/BuildLuarocks.cmake

@@ -34,6 +34,7 @@ function(BuildLuarocks)
       -DURL=${LUAROCKS_URL}
       -DEXPECTED_SHA256=${LUAROCKS_SHA256}
       -DTARGET=luarocks
+      -DUSE_EXISTING_SRC_DIR=${USE_EXISTING_SRC_DIR}
       -P ${CMAKE_CURRENT_SOURCE_DIR}/cmake/DownloadAndExtractFile.cmake
     BUILD_IN_SOURCE 1
     CONFIGURE_COMMAND "${_luarocks_CONFIGURE_COMMAND}"

third-party/cmake/BuildMsgpack.cmake

@@ -25,6 +25,7 @@ function(BuildMsgpack)
       -DURL=${MSGPACK_URL}
       -DEXPECTED_SHA256=${MSGPACK_SHA256}
       -DTARGET=msgpack
+      -DUSE_EXISTING_SRC_DIR=${USE_EXISTING_SRC_DIR}
       -P ${CMAKE_CURRENT_SOURCE_DIR}/cmake/DownloadAndExtractFile.cmake
     CONFIGURE_COMMAND "${_msgpack_CONFIGURE_COMMAND}"
     BUILD_COMMAND "${_msgpack_BUILD_COMMAND}"

third-party/cmake/BuildUnibilium.cmake

@@ -13,6 +13,7 @@ ExternalProject_Add(unibilium
     -DURL=${UNIBILIUM_URL}
     -DEXPECTED_SHA256=${UNIBILIUM_SHA256}
     -DTARGET=unibilium
+    -DUSE_EXISTING_SRC_DIR=${USE_EXISTING_SRC_DIR}
     -P ${CMAKE_CURRENT_SOURCE_DIR}/cmake/DownloadAndExtractFile.cmake
   CONFIGURE_COMMAND ""
   BUILD_IN_SOURCE 1

third-party/cmake/DownloadAndExtractFile.cmake

@@ -22,12 +22,15 @@ set(SRC_DIR ${PREFIX}/src/${TARGET})
 
 # Check whether the source has been downloaded. If true, skip it.
 # Useful for external downloads like homebrew.
-if(EXISTS "${SRC_DIR}" AND IS_DIRECTORY "${SRC_DIR}")
-  file(GLOB EXISTED_FILES "${SRC_DIR}/*")
-  if(EXISTED_FILES)
-    message(STATUS "${SRC_DIR} is found and not empty, skipping download and extraction. ")
-    return()
+if(USE_EXISTING_SRC_DIR)
+  if(EXISTS "${SRC_DIR}" AND IS_DIRECTORY "${SRC_DIR}")
+    file(GLOB EXISTED_FILES "${SRC_DIR}/*")
+    if(EXISTED_FILES)
+      message(STATUS "${SRC_DIR} is found and not empty, skipping download and extraction. ")
+      return()
+    endif()
   endif()
+  message(FATAL_ERROR "USE_EXISTING_SRC_DIR set to ON, but '${SRC_DIR}' does not exist or is empty.")
 endif()
 
 # Taken from ExternalProject_Add.  Let's hope we can drop this one day when