CMake: split out boost into its own CMakeLists

.gitignore

@@ -18,8 +18,6 @@ cmake-build-debug/
 !/build
 /build/*
 
-# Boost is downloaded and extracted to /third_party
-/third_party/boost*
 
 # Ignored files #
 *.obj

CMakeLists.txt

@@ -218,48 +218,6 @@ if (NOT TARGET libbacktrace)
     endif()
 endif()
 
-# Boost is downloaded if necessary
-
-# From https://www.boost.org/users/download/
-set(BOOST_VER 1.70.0)
-set(BOOST_HASH_TARGZ "882b48708d211a5f48e60b0124cf5863c1534cd544ecd0664bb534a4b5d506e9")
-set(BOOST_HASH_ZIP   "48f379b2e90dd1084429aae87d6bdbde9670139fa7569ee856c8c86dd366039d")
-
-string(REPLACE "." "_" BOOST_VER_FNAME ${BOOST_VER})
-set(BOOST_THIRD_PARTY_DIR ${CMAKE_CURRENT_SOURCE_DIR}/third_party/boost_${BOOST_VER_FNAME})
-
-function(DownloadBoost)
-    if (LINUX)
-        set(BOOST_EXT "tar.gz")
-        set(BOOST_HASH ${BOOST_HASH_TARGZ})
-    else()
-        set(BOOST_EXT "zip")
-        set(BOOST_HASH ${BOOST_HASH_ZIP})
-    endif()
-
-    # Note: bintray.com has rate limiting, so use the sourceforge mirror
-    # set(BOOST_URL https://dl.bintray.com/boostorg/release/${BOOST_VER}/source/boost_${BOOST_VER_FNAME}.${BOOST_EXT})
-    set(BOOST_URL https://iweb.dl.sourceforge.net/project/boost/boost/${BOOST_VER}/boost_${BOOST_VER_FNAME}.${BOOST_EXT})
-
-    if (NOT TARGET Boost::boost)
-        if(NOT EXISTS ${BOOST_THIRD_PARTY_DIR})
-            message(WARNING "
-          third_party/boost is missing.
-          Downloading and extracting boost:
-            ")
-
-            set(BOOST_ARCHIVE ${CMAKE_BINARY_DIR}/temp/boost_archive)
-            message(STATUS "Downloading ${BOOST_URL} to ${BOOST_ARCHIVE}...")
-            file(DOWNLOAD ${BOOST_URL} ${BOOST_ARCHIVE} EXPECTED_HASH SHA256=${BOOST_HASH})
-            message(STATUS "Extracting ${BOOST_ARCHIVE} to ${BOOST_THIRD_PARTY_DIR}...")
-            execute_process(
-                WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}/third_party
-                COMMAND cmake -E tar xf ${BOOST_ARCHIVE}
-            )
-        endif()
-    endif()
-endfunction()
-
 if(SWIFTSHADER_GET_PVR)
     if(NOT EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/third_party/PowerVR_Examples/.git)
         message(WARNING "
@@ -994,10 +952,7 @@ if(REACTOR_EMIT_DEBUG_INFO)
         target_link_libraries(${Reactor} libbacktrace)
     endif()
 
-    # Download boost and use it
-    DownloadBoost()
-    set(BOOST_INCLUDEDIR ${BOOST_THIRD_PARTY_DIR})
-    find_package(Boost REQUIRED)
+    add_subdirectory(third_party/boost)
     target_link_libraries(${Reactor} Boost::boost)
 endif(REACTOR_EMIT_DEBUG_INFO)
 

third_party/boost/CMakeLists.txt

+# Copyright 2020 The SwiftShader Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Boost is downloaded if necessary
+
+# From https://www.boost.org/users/download/
+set(BOOST_VER 1.70.0)
+set(BOOST_HASH_TARGZ "882b48708d211a5f48e60b0124cf5863c1534cd544ecd0664bb534a4b5d506e9")
+set(BOOST_HASH_ZIP   "48f379b2e90dd1084429aae87d6bdbde9670139fa7569ee856c8c86dd366039d")
+
+string(REPLACE "." "_" BOOST_VER_FNAME ${BOOST_VER})
+set(BOOST_PARENT_DIR ${CMAKE_CURRENT_BINARY_DIR})
+set(BOOST_DIR ${BOOST_PARENT_DIR}/boost_${BOOST_VER_FNAME})
+
+function(DownloadBoost)
+    if (LINUX)
+        set(BOOST_EXT "tar.gz")
+        set(BOOST_HASH ${BOOST_HASH_TARGZ})
+    else()
+        set(BOOST_EXT "zip")
+        set(BOOST_HASH ${BOOST_HASH_ZIP})
+    endif()
+
+    # Note: bintray.com has rate limiting, so use the sourceforge mirror
+    # set(BOOST_URL https://dl.bintray.com/boostorg/release/${BOOST_VER}/source/boost_${BOOST_VER_FNAME}.${BOOST_EXT})
+    set(BOOST_URL https://iweb.dl.sourceforge.net/project/boost/boost/${BOOST_VER}/boost_${BOOST_VER_FNAME}.${BOOST_EXT})
+
+    if (NOT TARGET Boost::boost)
+        if(NOT EXISTS ${BOOST_DIR})
+            message(WARNING "
+          ${BOOST_DIR} is missing.
+          Downloading and extracting boost:
+            ")
+
+            set(BOOST_ARCHIVE ${CMAKE_BINARY_DIR}/temp/boost_archive)
+            message(STATUS "Downloading ${BOOST_URL} to ${BOOST_ARCHIVE}...")
+            file(DOWNLOAD ${BOOST_URL} ${BOOST_ARCHIVE} EXPECTED_HASH SHA256=${BOOST_HASH})
+            message(STATUS "Extracting ${BOOST_ARCHIVE} to ${BOOST_DIR}...")
+            execute_process(
+                WORKING_DIRECTORY ${BOOST_PARENT_DIR}
+                COMMAND cmake -E tar xf ${BOOST_ARCHIVE}
+            )
+        endif()
+    endif()
+endfunction()
+
+DownloadBoost()
+
+set(BOOST_INCLUDEDIR ${BOOST_DIR})
+find_package(Boost REQUIRED)
+
+# Expose Boost::boost target for parent project
+add_library(boost INTERFACE)
+target_link_libraries(boost INTERFACE
+    Boost::boost
+)
+add_library(Boost::boost ALIAS boost)